research topics about water purification

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Recent advancements in water treatment

For immediate release, acs news service weekly presspac: january 19, 2022.

Generating clean, safe water is becoming increasingly difficult. Water sources themselves can be contaminated, but in addition, some purification methods can cause unintended harmful byproducts to form. And not all treatment processes are created equal with regard to their ability to remove impurities or pollutants. Below are some recent papers published in ACS journals that report insights into how well water treatment methods work and the quality of the resulting water. Reporters can request free access to these papers by emailing  newsroom@acs.org .

“Drivers of Disinfection Byproduct Cytotoxicity in U.S. Drinking Water: Should Other DBPs Be Considered for Regulation?” Environmental Science & Technology Dec.15, 2021

In this paper, researchers surveyed both conventional and advanced disinfection processes in the U.S., testing the quality of their drinking waters. Treatment plants with advanced removal technologies, such as activated carbon, formed fewer types and lower levels of harmful disinfection byproducts (known as DBPs) in their water. Based on the prevalence and cytotoxicity of haloacetonitriles and iodoacetic acids within some of the treated waters, the researchers recommend that these two groups be considered when forming future water quality regulations.

“Complete System to Generate Clean Water from a Contaminated Water Body by a Handmade Flower-like Light Absorber” ACS Omega Dec. 9, 2021 As a step toward a low-cost water purification technology, researchers crocheted a coated black yarn into a flower-like pattern. When the flower was placed in dirty or salty water, the water wicked up the yarn. Sunlight caused the water to evaporate, leaving the contaminants in the yarn, and a clean vapor condensed and was collected. People in rural locations could easily make this material for desalination or cleaning polluted water, the researchers say.

“Data Analytics Determines Co-occurrence of Odorants in Raw Water and Evaluates Drinking Water Treatment Removal Strategies” Environmental Science & Technology Dec. 2, 2021

Sometimes drinking water smells foul or “off,” even after treatment. In this first-of-its-kind study, researchers identified the major odorants in raw water. They also report that treatment plants using a combination of ozonation and activated carbon remove more of the odor compounds responsible for the stink compared to a conventional process. However, both methods generated some odorants not originally present in the water.

“Self-Powered Water Flow-Triggered Piezocatalytic Generation of Reactive Oxygen Species for Water Purification in Simulated Water Drainage” ACS ES&T Engineering Nov. 23, 2021

Here, researchers harvested energy from the movement of water to break down chemical contaminants. As microscopic sheets of molybdenum disulfide (MoS2) swirled inside a spiral tube filled with dirty water, the MoS2 particles generated electric charges. The charges reacted with water and created reactive oxygen species, which decomposed pollutant compounds, including benzotriazole and antibiotics. The researchers say these self-powered catalysts are a “green” energy resource for water purification.

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Current Water Treatment Technologies: An Introduction

• Reference work entry
• First Online: 11 July 2021
• pp 2033–2066
• Cite this reference work entry

• Na Tian 4 ,
• Yulun Nie 5 ,
• Xike Tian 5 &
• Yanxin Wang 6  

488 Accesses

2 Citations

Water treatment and purification in environmental protection are the worldwide issues to relieve the water shortage. At present, various treatment technologies for drinking water or wastewater have been developed. Hence, in this chapter, we will summarize the available water treatment and purification technologies including their advantages and disadvantages as well as the practical application. The main contents then can be divided into the following parts: Firstly, the purification processes for drinking water are introduced including the efficiency and mechanism of filtration and sedimentation, flocculation, disinfection, and other modern emerging technologies. Secondly, the principles and applications of existed wastewater treatment methods are summarized. Thirdly, the new technologies of water treatment are presented such as water reuse technology, membrane technology, advanced oxidation processes based deep water treatment technologies, etc. We think, by summarizing the recent literature and our preliminary work, the present chapter will give the basic information of various water treatment technologies for readers and further capitalize on these technologies for sustainable water management.

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Wastewater Treatment Technologies

Methods and Characteristics of Conventional Water Treatment Technologies

Petrie B, Barden R, Kasprzyk-Hordern B (2015) A review on emerging contaminants in wastewaters and the environment: current knowledge, understudied areas and recommendations for future monitoring. Water Res 72:3–27

Article   CAS   Google Scholar  

Sorensen JPR, Lapworth DJ, Nkhuwa DCW, Stuart ME, Gooddy DC, Bell RA, Chirwa M, Kabika J, Liemisa M, Chibesa M, Pedley S (2015) Emerging contaminants in urban groundwater sources in Africa. Water Res 72:51–63

Zhang FR, Song YW, Song S, Zhang RJ, Hou WG (2015) Synthesis of magnetite-graphene oxide-layered double hydroxide composites and applications for the removal of Pb(II) and 2,4-dichlorophenoxyacetic acid from aqueous solutions. ACS Appl Mater Interfaces 7:7251–7263

Gupta A, Chauhan VS, Sankararamakrishnan N (2009) Preparation and evaluation of iron-chitosan composites for removal of As(III) and As(V) from arsenic contaminated real life groundwater. Water Res 43:3862–3870

Kong SQ, Wang YX, Zhan HB, Liu ML, Liang LL, Hu QH (2014) Competitive adsorption of humic acid and arsenate on nanoscale iron–manganese binary oxide-loaded zeolite in groundwater. J Geochem Explor 144:220–225

Thong ZW, Han G, Cui Y, Gao J, Chung TS, Chan SY, Wei S (2014) Novel nanofiltration membranes consisting of a sulfonated pentablock copolymer rejection layer for heavy metal removal. Environ Sci Technol 48:13880–13887

Sun YB, Yang SB, Chen Y, Ding CC, Cheng WC, Wang XK (2015) Adsorption and desorption of U(VI) on functionalized graphene oxides: a combined experimental and theoretical study. Environ Sci Technol 49:4255–4262

Yang Y, Ok YS, Kim KH, Kwon EE, Tsang YF (2017) Occurrences and removal of pharmaceuticals and personal care products (PPCPs) in drinking water and water/sewage treatment plants: a review. Sci Total Environ 596–597:303–320

Ortiz M, Raluy RG, Serra L (2007) Life cycle assessment of water treatment technologies: wastewater and water-reuse in a small town. Desalination 204:121–131

Igunnu ET, Chen GZ (2014) Produced water treatment technologies. Int J Low-Carbon Technol 9:157–177

Qu XL, Alvarez PJ, Li QL (2013) Applications of nanotechnology in water and wastewater treatment. Water Res 47:3931–3946

Sonune A, Ghate R (2004) Developments in wastewater treatment methods. Desalination 167:55–63

Ternes TA, Meisenheimer M, Mcdowell D, Sacher F, Brauch HJ, Haist-Gulde B, Preuss G, Wilme U, Zulei-Seibert N (2002) Removal of pharmaceuticals during drinking water treatment. Environ Sci Technol 36:3855–3863

Krasner SW, McGuire MJ, Jacangelo JG, Patania NL, Reagan KM, Aieta EM (1989) The occurrence of disinfection by-products in US drinking water. J Am Water Works Ass 81:41–53

Gunten UV (2003) Ozonation of drinking water: part I. Oxidation kinetics and product formation. Water Res 37:1443–1467

Azimi A, Azari A, Rezakazemi M, Ansarpour M (2017) Removal of heavy metals from industrial wastewaters: a review. ChemBioEng Rev 4:37–59

Article   Google Scholar  

Vymazal J (2014) Constructed wetlands for treatment of industrial wastewaters: a review. Ecol Eng 73:724–751

Bautista P, Mohedano AF, Casas JA, Zazo JA, Rodriguez JJ (2008) An overview of the application of Fenton oxidation to industrial wastewaters treatment. J Chem Technol Biotechnol 83:1323–1338

Moussavi G, Mahmoudi M (2009) Removal of azo and anthraquinone reactive dyes from industrial wastewaters using MgO nanoparticles. J Hazard Mater 168:806–812

Gehrke I, Geiser A, Somborn-Schulz A (2015) Innovations in nanotechnology for water treatment. Nanotechnol Sci Appl 8:1–17

Krzeminski P, Tomei MC, Karaolia P, Langenhoff A, Almeida CMR, Felis E, Gritten F, Andersen HR, Fernandes T, Manaia CM, Rizzo L, Fatta-Kassinos D (2019) Performance of secondary wastewater treatment methods for the removal of contaminants of emerging concern implicated in crop uptake and antibiotic resistance spread: a review. Sci Total Environ 648:1052–1081

Ali I, Peng CS, Khan ZM, Naz I, Sultan M, Ali M, Abbasi IA, Islam T, Ye T (2019) Overview of microbes based fabricated biogenic nanoparticles for water and wastewater treatment. J Environ Manag 230:128–150

Muzammil Anjum RM, Waqas M, Gehany F, Barakat MA (2019) Remediation of wastewater using various nano-materials. Arab J Chem 12:4897–4919

Kim KH, Ihm SK (2011) Heterogeneous catalytic wet air oxidation of refractory organic pollutants in industrial wastewaters: a review. J Hazard Mater 186:16–34

Samaei SM, Gato-Trinidad S, Altaee A (2018) The application of pressure-driven ceramic membrane technology for the treatment of industrial wastewaters – a review. Sep Purif Technol 200:198–220

Chowdhury S, Mazumder MAJ, Al-Attas O, Husain T (2016) Heavy metals in drinking water: occurrences, implications, and future needs in developing countries. Sci Total Environ 569–570:476–488

Garfí M, Cadena E, Sanchez-Ramos D, Ferrer I (2016) Life cycle assessment of drinking water: comparing conventional water treatment, reverse osmosis and mineral water in glass and plastic bottles. J Clean Prod 137:997–1003

Sharma S, Bhattacharya A (2017) Drinking water contamination and treatment techniques. Appl Water Sci 7:1043–1067

Muhamad MS, Salim MR, Lau WJ, Yusop Z (2016) A review on bisphenol A occurrences, health effects and treatment process via membrane technology for drinking water. Environ Sci Pollut Res Int 23:11549–11567

Glaze WH (1987) Drinking-water treatment with ozone. Environ Sci Technol 21:224–230

Sillanpaa M, Ncibi MC, Matilainen A, Vepsalainen M (2018) Removal of natural organic matter in drinking water treatment by coagulation: a comprehensive review. Chemosphere 190:54–71

Moon J, Kang MS, Lim JL, Kim CH, Park HD (2009) Evaluation of a low-pressure membrane filtration for drinking water treatment: pretreatment by coagulation/sedimentation for the MF membrane. Desalination 247:271–284

Hall ER, Monti A, Mohn WW (2010) A comparison of bacterial populations in enhanced biological phosphorus removal processes using membrane filtration or gravity sedimentation for solids-liquid separation. Water Res 44:2703–2714

Martinez-Huitle CA, Brillas E (2008) Electrochemical alternatives for drinking water disinfection. Angew Chem Int Ed 47:1998–2005

Aboulhassan MA, Souabi S, Yaacoubi A, Baudu M (2006) Removal of surfactant from industrial wastewaters by coagulation flocculation process. Int J Environ Sci Technol 3:327–332

Asami T, Katayama H, Torrey JR, Visvanathan C, Furumai H (2016) Evaluation of virus removal efficiency of coagulation-sedimentation and rapid sand filtration processes in a drinking water treatment plant in Bangkok, Thailand. Water Res 101:84–94

Volk C, Bell K, Ibrahim E, Verges D, Amy G, LeChevallier M (2000) Impact of enhanced and optimized coagulation on removal of organic matter and its biodegradable fraction in drinking water. Water Res 34:3247–3257

Sharp EL, Jarvis P, Parsons SA, Jefferson B (2006) Impact of fractional character on the coagulation of NOM. Colloids Surf A Physicochem Eng Asp 286:104–111

Henderson R, Sharp E, Jarvis P, Parsons S, Jefferson B (2006) Identifying the linkage between particle characteristics and understanding coagulation performance. In: Han MY, Park KH, Dockko S (eds) Particle separation 2005 – drinking water treatment. Iwa Publishing, London, pp 31–38

Google Scholar  

Duan JM, Gregory J (2003) Coagulation by hydrolysing metal salts. Adv Colloid Interf Sci 100–102:475–502

Yang C, Gao LL, Wang YX, Tian XK, Komarneni S (2014) Fluoride removal by ordered and disordered mesoporous aluminas. Microporous Mesoporous Mater 197:156–163

Daud Z, Awang H, Latif AAA, Nasir N, Ridzuan MB, Ahmad Z (2015) Suspended solid, color, COD and oil and grease removal from biodiesel wastewater by coagulation and flocculation processes. Procedia Soc Behav Sci 195:2407–2411

Di Bella G, Giustra MG, Freni G (2014) Optimisation of coagulation/flocculation for pre-treatment of high strength and saline wastewater: performance analysis with different coagulant doses. Chem Eng J 254:283–292

Kabdaşlı I, Arslan-Alaton I, Ölmez-Hancı T, Tünay O (2012) Electrocoagulation applications for industrial wastewaters: a critical review. Environ Technol Rev 1:2–45

Jarvis P, Sharp E, Pidou M, Molinder R, Parsons SA, Jefferson B (2012) Comparison of coagulation performance and floc properties using a novel zirconium coagulant against traditional ferric and alum coagulants. Water Res 46:4179–4187

Lu WM, Tung KL, Pan CH, Hwang KJ (1998) The effect of particle sedimentation on gravity filtration. Sep Sci Technol 33:1723–1746

Zhang JN, Lin T, Chen W (2017) Micro-flocculation/sedimentation and ozonation for controlling ultrafiltration membrane fouling in recycling of activated carbon filter backwash water. Chem Eng J 325:160–168

Yim SS, Kwon YD (1997) A unified theory on solid-liquid separation- filtration, expression, sedimentation, filtration by centrifugal force, and cross flow filtration. Korean J Chem Eng 14:354–358

Font R, HernÁNdez A (2000) Filtration with sedimentation: application of Kynchs theorems. Sep Sci Technol 35:183–210

Tiller FM, Hsyung NB (1995) Role of porosity in filtration- XII. Filtration with sedimentation. AICHE J 41:1153–1164

Tiehm A, Herwig V, Neis U (1999) Particle size analysis for improved sedimentation and filtration in waste water treatment. Water Sci Technol 39:99–106

Hawkes JJ, Limaye MS, Coakley WT (1997) Filtration of bacteria and yeast by ultrasound-enhanced sedimentation. J Appl Microbiol 82:39–47

Kato R, Asami T, Utagawa E, Furumai H, Katayama H (2018) Pepper mild mottle virus as a process indicator at drinking water treatment plants employing coagulation-sedimentation, rapid sand filtration, ozonation, and biological activated carbon treatments in Japan. Water Res 132:61–70

Albinana-Gimenez N, Miagostovich MP, Calgua B, Huguet JM, Matia L, Girones R (2009) Analysis of adenoviruses and polyomaviruses quantified by qPCR as indicators of water quality in source and drinking-water treatment plants. Water Res 43:2011–2019

Albinana-Gimenez N, Clemente-Casares P, Calgua B, Huguet JM, Courtois S, Girones R (2009) Comparison of methods for concentrating human adenoviruses, polyomavirus JC and noroviruses in source waters and drinking water using quantitative PCR. J Virol Methods 158:104–109

Haramoto E, Kitajima M, Kishida N, Konno Y, Katayama H, Asami M, Akiba M (2013) Occurrence of pepper mild mottle virus in drinking water sources in Japan. Appl Environ Microbiol 79:7413–7418

Gimbert LJ, Haygarth PM, Beckett R, Worsfold PJ (2005) Comparison of centrifugation and filtration techniques for the size fractionation of colloidal material in soil suspensions using sedimentation field-flow fractionation. Environ Sci Technol 39:1731–1735

Pavlovic I, Perez MR, Barriga C, Ulibarri MA (2009) Adsorption of Cu 2+ , Cd 2+ and Pb 2+ ions by layered double hydroxides intercalated with the chelating agents diethylenetriaminepentaacetate and meso-2,3-dimercaptosuccinate. Appl Clay Sci 43:125–129

Humplik T, Lee J, O’Hern SC, Fellman BA, Baig MA, Hassan SF, Atieh MA, Rahman F, Laoui T, Karnik R (2011) Nanostructured materials for water desalination. Nanotechnology 22:2788–2794

Zevenbergen C, Van Reeuwijk LP, Frapporti G, Louws RJ, Schuiling RD (1996) A simple method for defluoridation of drinking water at village level by adsorption on Ando soil in Kenya. Sci Total Environ 188:225–232

Loganathan P, Vigneswaran S, Kandasamy J, Naidu R (2013) Defluoridation of drinking water using adsorption processes. J Hazard Mater 248–249:1–19

Babi KG, Koumenides KM, Nikolaou AD, Makri CA, Tzoumerkas FK, Lekkas TD (2007) Pilot study of the removal of THMs, HAAs and DOC from drinking water by GAC adsorption. Desalination 210:215–224

Tian XK, Wu QY, Wong KM, Yang C, Wang WW, Wu XN, Wang YX, Zhang SX, Lei Y (2013) A simple technique for the facile synthesis of novel crystalline mesoporous ZrO 2 -Al­ 2 O 3 hierarchical nanostructures with high lead (II) ion absorption ability. Appl Surf Sci 284:412–418

Tian XK, Wang WW, Tian N, Zhou CX, Yang C, Komarneni S (2016) Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe 3 O 4 /halloysite nanohybrid. J Hazard Mater 309:151–156

Mellouk S, Belhakem A, Marouf-Khelifa K, Schott J, Khelifa A (2011) Cu(II) adsorption by halloysites intercalated with sodium acetate. J Colloid Interface Sci 360:716–724

Liu L, Wan YZ, Xie YD, Zhai R, Zhang B, Liu JD (2012) The removal of dye from aqueous solution using alginate-halloysite nanotube beads. Chem Eng J 187:210–216

Tian XK, Wang WW, Wang YX, Komarneni S, Yang C (2015) Polyethylenimine functionalized halloysite nanotubes for efficient removal and fixation of Cr (VI). Microporous Mesoporous Mater 207:46–52

Wang JH, Zhang X, Zhang B, Zhao YF, Zhai R, Liu JD, Chen RF (2010) Rapid adsorption of Cr (VI) on modified halloysite nanotubes. Desalination 259:22–28

Zhao YF, Abdullayev E, Vasiliev A, Lvov Y (2013) Halloysite nanotubule clay for efficient water purification. J Colloid Interface Sci 406:121–129

Alkan M, Çelikçapa S, Demirbaş Ö, Doğan M (2005) Removal of reactive blue 221 and acid blue 62 anionic dyes from aqueous solutions by sepiolite. Dyes Pigments 65:251–259

Brigatti MF, Medici L, Poppi L (1996) Sepiolite and industrial waste-water purification: removal of Zn 2+ and Pb 2+ from aqueous solutions. Appl Clay Sci 11:43–54

Kara M, Yuzer H, Sabah E, Celik MS (2003) Adsorption of cobalt from aqueous solutions onto sepiolite. Water Res 37:224–232

Marjanović V, Lazarević S, Janković-Častvan I, Potkonjak B, Đ Janaćković R (2011) Petrović, Chromium(VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites. Chem Eng J 166:198–206

Kocaoba S (2009) Adsorption of Cd(II), Cr(III) and Mn(II) on natural sepiolite. Desalination 244:24–30

Serratosa JM (1979) Surface properties of fibrous clay minerals (palygorskite and sepiolite). Dev Sedimentol 27:99–109

Galan E (1996) Properties and application of palygorskite-sepiolite clays. Clay Miner 31:443–453

Joussein E, Petit S, Churchman J, Theng B, Righi D, Delvaux B (2005) Halloysite clay minerals-a review. Clay Miner 40:383–426

Du ML, Guo BC, Jia DM (2010) Newly emerging applications of halloysite nanotubes: a review. Polym Int 59:574–582

Belkassa K, Bessaha F, Marouf-Khelifa K, Batonneau-Gener I, Comparot J, Khelifa A (2013) Physicochemical and adsorptive properties of a heat-treated and acid-leached Algerian halloysite. Colloid Surf A 421:26–33

Matusik J (2016) Halloysite for adsorption and pollution remediation. In: Peng Y, Thill A, Faïza B (eds) Developments in clay science. Elsevier, pp 606–627

Tian N, Tian XK, Ma LL, Yang C, Wang YX, Wang ZY, Zhang LD (2015) Well-dispersed magnetic iron oxide nanocrystals on sepiolite nanofibers for arsenic removal. RSC Adv 5:25236–25243

Tian N, Tian XK, Liu XW, Zhou ZX, Yang C, Ma LL, Tian C, Li Y, Wang YX (2016) Facile synthesis of hierarchical dendrite-like structure iron layered double hydroxide nanohybrids for effective arsenic removal. Chem Commun 52:11955–11958

Li Q, Mahendra S, Lyon DY, Brunet L, Liga MV, Li D, Alvarez PJ (2008) Antimicrobial nanomaterials for water disinfection and microbial control: potential applications and implications. Water Res 42:4591–4602

Hua GH, Reckhow DA (2007) Comparison of disinfection byproduct formation from chlorine and alternative disinfectants. Water Res 41:1667–1678

Li XF, Mitch WA (2018) Drinking water disinfection byproducts (DBPs) and human health effects: multidisciplinary challenges and opportunities. Environ Sci Technol 52:1681–1689

Malato S, Fernández-Ibáñez P, Maldonado MI, Blanco J, Gernjak W (2009) Decontamination and disinfection of water by solar photocatalysis: recent overview and trends. Catal Today 147:1–59

Giannakis S, López MIP, Spuhler D, Pérez JAS, Ibáñez PF, Pulgarin C (2016) Solar disinfection is an augmentable, in situ-generated photo-Fenton reaction – part 2: a review of the applications for drinking water and wastewater disinfection. Appl Catal B Environ 198:431–446

Ma SL, Zhan SH, Jia YN, Shi Q, Zhou QX (2016) Enhanced disinfection application of Ag-modified g-C 3 N 4 composite under visible light. Appl Catal B Environ 186:77–87

Kimura SY, Komaki Y, Plewa MJ, Marinas BJ (2013) Chloroacetonitrile and N,2-dichloroacetamide formation from the reaction of chloroacetaldehyde and monochloramine in water. Environ Sci Technol 47:12382–12390

Villanueva CM, Cordier S, Font-Ribera L, Salas LA, Levallois P (2015) Overview of disinfection by-products and associated health effects. Curr Environ Health Rep 2:107–115

Rook JJ (1974) Formation of haloforms during chlorination of natural waters. Water Treat Examinat 23:234–243

Jeong CH, Postigo C, Richardson SD, Simmons JE, Kimura SY, Marinas BJ, Barcelo D, Liang P, Wagner ED, Plewa MJ (2015) Occurrence and comparative toxicity of haloacetaldehyde disinfection byproducts in drinking water. Environ Sci Technol 49:13749–13759

Singer PC (1994) Control of disinfection by-products in drinking water. J Environ Eng 120:727–744

Richardson SD (2003) Disinfection by-products and other emerging contaminants in drinking water. Trends Anal Chem 22:666–684

Simpson KL, Hayes KP (1998) Drinking water disinfection by-products: an Australian perspective. Water Res 32:1522–1528

Williams DT, LeBel GL, Benoit FM (1997) Disinfection by-products in Canadian drinking water. Chemosphere 34:299–316

John DE, Haas CN, Nwachuku N, Gerba CP (2005) Chlorine and ozone disinfection of encephalitozoon intestinalis spores. Water Res 39:2369–2375

Xu P, Janex ML, Savoye P, Cockx A (2002) Wastewater disinfection by ozone: main parameters for process design. Water Res 36:1043–1055

Cho M, Chung H, Yoon J (2003) Disinfection of water containing natural organic matter by using ozone-initiated radical reactions. Appl Environ Microbiol 69:2284–2291

Zeng XK, Wang ZY, Wang G, Gengenbach TR, David T, McCarthy A, Deletic JGY, Zhang XW (2017) Highly dispersed TiO 2 nanocrystals and WO 3 nanorods on reduced graphene oxide: Z-scheme photocatalysis system for accelerated photocatalytic water disinfection. Appl Catal B Environ 218:163–173

Fernández-Ibáñez P, Polo-López MI, Malato S, Wadhwa S, Hamilton JWJ, Dunlop PSM, D’Sa R, Magee E, O’Shea K, Dionysiou DD, Byrne JA (2015) Solar photocatalytic disinfection of water using titanium dioxide graphene composites. Chem Eng J 261:36–44

Wolfe RL (1990) Ultraviolet disinfection of potable water. Environ Sci Technol 24:768–773

Yu JC, Ho WK, Yu JG, Yip H, Wong PK, Zhao JC (2005) Efficient visible-light-induced photocatalytic disinfection on sulfur-doped nanocrystalline titania. Environ Sci Technol 39:1175–1179

Kraft A (2008) Electrochemical water disinfection: a short review. Platin Met Rev 52:177–185

Patermarakis G, Fountoukidis E (1990) Disinfection of water by electrochemical treatment. Water Res 24:1491–1496

Song K, Mohseni M, Taghipour F (2016) Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: a review. Water Res 94:341–349

Kitis M (2004) Disinfection of wastewater with peracetic acid: a review. Environ Int 30:47–55

Blume T, Neis U (2004) Improved wastewater disinfection by ultrasonic pre-treatment. Ultrason Sonochem 11:333–336

Jeong J, Kim C, Yoon J (2009) The effect of electrode material on the generation of oxidants and microbial inactivation in the electrochemical disinfection processes. Water Res 43:895–901

Kerwick MI, Reddy SM, Chamberlain AHL, Holt DM (2005) Electrochemical disinfection, an environmentally acceptable method of drinking water disinfection? Electrochim Acta 50:5270–5277

Huang X, Qu Y, Cid CA, Finke C, Hoffmann MR, Lim K, Jiang SC (2016) Electrochemical disinfection of toilet wastewater using wastewater electrolysis cell. Water Res 92:164–172

Muralikrishna IV, Manickam V (2017) Wastewater treatment technologies. In: Environmental management. Elsevier, pp 249–293

Chapter   Google Scholar  

Amuda OS, Amoo IA (2007) Coagulation/flocculation process and sludge conditioning in beverage industrial wastewater treatment. J Hazard Mater 141:778–783

Dabrowski A, Hubicki Z, Podkoscielny P, Robens E (2004) Selective removal of the heavy metal ions from waters and industrial wastewaters by ion-exchange method. Chemosphere 56:91–106

Atlow SC, Bonadonna-Aparo L, Klibanov AM (1984) Dephenolization of industrial wastewaters catalyzed by polyphenol oxidase. Biotechnol Bioeng 26:599–603

Glaze WH, Kang JW, Chapin DH (1987) The chemistry of water treatment processes involving ozone, hydrogen peroxide and ultraviolet radiation. Ozone Sci Eng 9:335–352

Epa U (2011) Principles of design and operations of wastewater treatment pond systems for plant operators, engineers, and managers. United States Environmental Protection Agency, Office of Research and Development

Tünay O, Kabdasli I, Orhon D, Kolçak S (1997) Ammonia removal by magnesium ammonium phosphate precipitation in industrial wastewaters. Water Sci Technol 36:225–228

Birge WJ, Black JA, Short TM, Westerm AG (1989) A comparative ecological and toxicological investigation of a secondary wastewater treatment plant effluent and its receiving stream. Environ Toxicol Chem 8:437–450

Munkittrick KR, Van Der Kraak GJ, Mcmaster ME, Port CB (1992) Response of hepatic mfo activity and plasma sex steroids to secondary treatment of bleached Kraft pulp mill effluent and mill shutdown. Environ Toxicol Chem 11:1427–1439

Wu Y, Chung A, Tam NFY, Pi N, Wong MH (2008) Constructed mangrove wetland as secondary treatment system for municipal wastewater. Ecol Eng 34:137–146

Ubukata Y, Takii S (1994) Induction ability of excess phosphate accumulation for phosphate removing bacteria. Water Res 28:247–249

Lehman SG, Liu L (2009) Application of ceramic membranes with pre-ozonation for treatment of secondary wastewater effluent. Water Res 43:2020–2028

Lin HJ, Chen JR, Wang FY, Ding LX, Hong HC (2011) Feasibility evaluation of submerged anaerobic membrane bioreactor for municipal secondary wastewater treatment. Desalination 280:120–126

Sarria V, Parra S, Adler N, Péringer P, Benitez N, Pulgarin C (2002) Recent developments in the coupling of photoassisted and aerobic biological processes for the treatment of biorecalcitrant compounds. Catal Today 76:301–315

Wang XJ, Song Y, Mai JS (2008) Combined Fenton oxidation and aerobic biological processes for treating a surfactant wastewater containing abundant sulfate. J Hazard Mater 160:344–348

Rittmann BE (1987) Aerobic biological treatment: water treatment processes. Environ Sci Technol 21(2):128–136

Tomlinson TG, Boon AG, Trotman CNA (1966) Inhibition of nitrification in the activated sludge process of sewage disposal. J Appl Bacteriol 29:266–291

Li B, Zhang T (2010) Biodegradation and adsorption of antibiotics in the activated sludge process. Environ Sci Technol 44:3468–3473

Fuhs GW, Chen M (1975) Microbiological basis of phosphate removal in the activated sludge process for the treatment of wastewater. Microb Ecol 2:119–138

Lin AY, Yu TH, Lateef SK (2009) Removal of pharmaceuticals in secondary wastewater treatment processes in Taiwan. J Hazard Mater 167:1163–1169

Liao BQ, Kraemer JT, Bagley DM (2006) Anaerobic membrane bioreactors: applications and research directions. Crit Rev Environ Sci Technol 36:489–530

Lin HJ, Xie K, Mahendran B, Bagley DM, Leung KT, Liss SN, Liao BQ (2009) Sludge properties and their effects on membrane fouling in submerged anaerobic membrane bioreactors (SAnMBRs). Water Res 43:3827–3837

Zhang XY, Wang ZW, Wu ZC, Lu FH, Tong J, Zang LL (2010) Formation of dynamic membrane in an anaerobic membrane bioreactor for municipal wastewater treatment. Chem Eng J 165:175–183

Lin HJ, Peng W, Zhang MJ, Chen JR, Hong HC, Zhang Y (2013) A review on anaerobic membrane bioreactors: applications, membrane fouling and future perspectives. Desalination 314:169–188

Koivunen J, Siitonen A, Heinonen-Tanski H (2003) Elimination of enteric bacteria in biological-chemical wastewater treatment and tertiary filtration units. Water Res 37:690–698

Gómez M, Plazab F, Garralón G, Pérez J, Gómez MA (2007) A comparative study of tertiary wastewater treatment by physico-chemical-UV process and macrofiltration-ultrafiltration technologies. Desalination 202:369–376

Sérodes JB, Walsh E, Goulet O (2011) Tertiary treatment of municipal wastewater using bioflocculating micro-algae. Can J Civ Eng 18:940–944

Wu J, Yang YS, Lin J (2005) Advanced tertiary treatment of municipal wastewater using raw and modified diatomite. J Hazard Mater 127:196–203

Ince NH (1998) Light-enhanced chemical oxidation for tertiary treatment of municipal landfill leachate. Water Environ Res 70:1161–1169

Vijayalakshmi P, Raju GB, Gnanamani A (2011) Advanced oxidation and electrooxidation as tertiary treatment techniques to improve the purity of tannery wastewater. Ind Eng Chem Res 50:10194–10200

Liu F, Zhao CC, Zhao DF, Liu GH (2008) Tertiary treatment of textile wastewater with combined media biological aerated filter (CMBAF) at different hydraulic loadings and dissolved oxygen concentrations. J Hazard Mater 160:161–167

Wei XC, Viadero RC Jr, Bhojappa S (2008) Phosphorus removal by acid mine drainage sludge from secondary effluents of municipal wastewater treatment plants. Water Res 42:3275–3284

Araña J, Herrera Melián JA, Doña Rodrıguez JM, González Dıaz O, Viera A, Pérez Peña J, Marrero Sosa PM, Espino Jiménez V (2002) TiO 2 -Photocatalysis as a tertiary treatment of naturally treat waste-water. Catal Today 76:279–289

Zhi D, Wang JB, Zhou YY, Luo ZR, Sun YQ, Wan ZH, Luo L, Tsang DCW, Dionysiou DD (2020) Development of ozonation and reactive electrochemical membrane coupled process: enhanced tetracycline mineralization and toxicity reduction. Chem Eng J 383:123149–123158

Viet ND, Cho J, Yoon Y, Jang A (2019) Enhancing the removal efficiency of osmotic membrane bioreactors: a comprehensive review of influencing parameters and hybrid configurations. Chemosphere 236:124363–124381

Hassan M, Olvera-Vargas H, Zhu XP, Zhang B, He YL (2019) Microbial electro-Fenton: an emerging and energy-efficient platform for environmental remediation. J Power Sources 424:220–244

Kamali M, Suhas DP, Costa ME, Capela I, Aminabhavi TM (2019) Sustainability considerations in membrane-based technologies for industrial effluents treatment. Chem Eng J 368:474–494

Rossignol N, Vandanjon L, Jaouen P, Quemeneur F (1999) Membrane technology for the continuous separation microalgae-culture medium-compared performances of cross-flow microfiltration and ultrafiltration. Aquac Eng 20:191–208

Nabeel F, Rasheed T, Bilal M, Iqbal HMN (2019) Supramolecular membranes: a robust platform to develop separation strategies towards water-based applications. Sep Purif Technol 215:441–453

Jacangelo JG, Trussell RR, Watson M (1997) Role of membrane technology in drinking water treatment in the United States. Desalination 113:119–127

Saleem H, Trabzon L, Kilic A, Zaidi SJ (2020) Recent advances in nanofibrous membranes: production and applications in water treatment and desalination. Desalination 478:114178–114218

Khanzada NK, Farid MU, Kharraz JA, Choi J, Tang CY, Nghiem LD, Jang A, An AK (2020) Removal of organic micropollutants using advanced membrane-based water and wastewater treatment: a review. J Membr Sci 598:117672–117709

Madaeni SS (1999) The application of membrane technology for water disinfection. Water Res 33:301–308

Matter CG (2018) Membrane filtration (micro and ultrafiltration) in water purification. Springer International Publishing AG

Yu W, Brown M, Graham NJ (2016) Prevention of PVDF ultrafiltration membrane fouling by coating MnO 2 nanoparticles with ozonation. Sci Rep 6:30144–30156

Yoon J, Amy G, Chung J, Sohn J, Yoon Y (2009) Removal of toxic ions (chromate, arsenate, and perchlorate) using reverse osmosis, nanofiltration, and ultrafiltration membranes. Chemosphere 77:228–235

Kwon Y, Lee DG (2019) Removal of contaminants of emerging concern (CECs) using a membrane bioreactor (MBR): a short review. Global NEST J 21:337–346

CAS   Google Scholar  

Iorhemen OT, Hamza RA, Tay JH (2016) Membrane bioreactor (MBR) Technology for Wastewater Treatment and Reclamation: membrane fouling. Membranes (Basel) 6:33–62

Arefi-Oskoui S, Khataee A, Safarpour M, Orooji Y, Vatanpour V (2019) A review on the applications of ultrasonic technology in membrane bioreactors. Ultrason Sonochem 58:104633–104648

Zhen GY, Pan Y, Lu XQ, Li YY, Zhang ZY, Niu CX, Kumar G, Kobayashi T, Zhao YC, Xu KQ (2019) Anaerobic membrane bioreactor towards biowaste biorefinery and chemical energy harvest: recent progress, membrane fouling and future perspectives. Renew Sust Energ Rev 115:109392–109416

Li KL, Xu LL, Zhang Y, Cao AX, Wang YJ, Huang HO, Wang J (2019) A novel electro-catalytic membrane contactor for improving the efficiency of ozone on wastewater treatment. Appl Catal B Environ 249:316–321

Tang SY, Zhang LX, Peng Y, Liu J, Zhang X, Zhang ZH (2019) Fenton cleaning strategy for ceramic membrane fouling in wastewater treatment. J Environ Sci (China) 85:189–199

Li QL, Kong H, Li P, Shao JH, He YL (2019) Photo-Fenton degradation of amoxicillin via magnetic TiO 2 -graphene oxide-Fe 3 O 4 composite with a submerged magnetic separation membrane photocatalytic reactor (SMSMPR). J Hazard Mater 373:437–446

Chan SHS, Yeong Wu T, Juan JC, Teh CY (2011) Recent developments of metal oxide semiconductors as photocatalysts in advanced oxidation processes (AOPs) for treatment of dye waste-water. J Chem Technol Biotechnol 86:1130–1158

Oturan MA, Aaron JJ (2014) Advanced oxidation processes in water/wastewater treatment: principles and applications. A review. Crit Rev Environ Sci Technol 44:2577–2641

Pignatello JJ, Oliveros E, MacKay A (2006) Advanced oxidation processes for organic contaminant destruction based on the Fenton reaction and related chemistry. Crit Rev Environ Sci Technol 36:1–84

Wang J, Wang S (2016) Removal of pharmaceuticals and personal care products (PPCPs) from wastewater: a review. J Environ Manag 182:620–640

Cheng M, Zeng GM, Huang DL, Lai C, Xu P, Zhang C, Liu Y (2016) Hydroxyl radicals based advanced oxidation processes (AOPs) for remediation of soils contaminated with organic compounds: a review. Chem Eng J 284:582–598

Hu PD, Long MC (2016) Cobalt-catalyzed sulfate radical-based advanced oxidation: a review on heterogeneous catalysts and applications. Appl Catal B Environ 181:103–117

Bethi B, Sonawane SH, Bhanvase BA, Gumfekar SP (2016) Nanomaterials-based advanced oxidation processes for wastewater treatment: a review. Chem Eng Process Process Intensif 109:178–189

Khatri J, Nidheesh PV, Anantha Singh TS, Suresh Kumar M (2018) Advanced oxidation processes based on zero-valent aluminium for treating textile wastewater. Chem Eng J 348:67–73

Guzzella L, Feretti D, Monarca S (2002) Advanced oxidation and adsorption technologies for organic micropollutant removal from lake water used as drinking-water supply. Water Res 36:4307–4318

Clarizia L, Russo D, Di Somma I, Marotta R, Andreozzi R (2017) Homogeneous photo-Fenton processes at near neutral pH: a review. Appl Catal B Environ 209:358–371

Pliego G, Zazo JA, Garcia-Muñoz P, Munoz M, Casas JA, Rodriguez JJ (2015) Trends in the intensification of the Fenton process for wastewater treatment: an overview. Crit Rev Environ Sci Technol 45:2611–2692

Wang W, Huang G, Yu JC, Wong PK (2015) Advances in photocatalytic disinfection of bacteria: development of photocatalysts and mechanisms. J Environ Sci 34:232–247

Tušar NN, Maučec D, Rangus M, Arčon I, Mazaj M, Cotman M, Pintar A, Kaučič V (2012) Manganese functionalized silicate nanoparticles as a Fenton-type catalyst for water purification by advanced oxidation processes (AOP). Adv Funct Mater 22:820–826

Chen LW, Li XC, Zhang J, Fang JY, Huang YM, Wang P, Ma J (2015) Production of hydroxyl radical via the activation of hydrogen peroxide by hydroxylamine. Environ Sci Technol 49:10373–10379

Wang JL, Xu LJ (2012) Advanced oxidation processes for wastewater treatment: formation of hydroxyl radical and application. Crit Rev Environ Sci Technol 42:251–325

Bokare AD, Choi W (2014) Review of iron-free Fenton-like systems for activating H 2 O 2 in advanced oxidation processes. J Hazard Mater 275:121–135

Jin H, Tian XK, Nie YL, Zhou ZX, Yang C, Li Y, Lu LQ (2017) Oxygen vacancy promoted heterogeneous Fenton-like degradation of Ofloxacin at pH 3.2–9.0 by Cu substituted magnetic Fe 3 O 4 @FeOOH Nanocomposite. Environ Sci Technol 51:12699–12706

Dai C, Tian XK, Nie YL, Lin HM, Yang C, Han B, Wang YX (2018) Surface facet of CuFeO 2 nanocatalyst: a key parameter for H 2 O 2 activation in Fenton-like reaction and organic pollutant degradation. Environ Sci Technol 52:6518–6525

Zhou Y, Jiang J, Gao Y, Pang SY, Yang Y, Ma J, Gu J, Li J, Wang Z, Wang LH, Yuan LP, Yang Y (2017) Activation of peroxymonosulfate by phenols: important role of quinone intermediates and involvement of singlet oxygen. Water Res 125:209–218

Wang Z, Bush RT, Sullivan LA, Chen C, Liu J (2014) Selective oxidation of arsenite by peroxymonosulfate with high utilization efficiency of oxidant. Environ Sci Technol 48:3978–3985

Liang C, Huang CF, Mohanty N, Kurakalva RM (2008) A rapid spectrophotometric determination of persulfate anion in ISCO. Chemosphere 73:1540–1543

Huang GX, Wang CY, Yang CW, Guo PC, Yu HQ (2017) Degradation of bisphenol A by peroxymonosulfate catalytically activated with Mn 1.8 Fe 1.2 O 4 nanospheres: synergism between Mn and Fe. Environ Sci Technol 51:12611–12618

Qi CD, Liu XT, Ma J, Lin CY, Li XW, Zhang HJ (2016) Activation of peroxymonosulfate by base: implications for the degradation of organic pollutants. Chemosphere 151:280–288

Zhou Y, Jiang J, Gao Y, Ma J, Pang SY, Li J, Lu XT, Yuan LP (2015) Activation of peroxymonosulfate by benzoquinone: a novel nonradical oxidation process. Environ Sci Technol 49:12941–12950

Tian N, Tian XK, Nie YL, Yang C, Zhou ZX, Li Y (2018) Biogenic manganese oxide: an efficient peroxymonosulfate activation catalyst for tetracycline and phenol degradation in water. Chem Eng J 352:469–476

Tian N, Tian XK, Nie YL, Yang C, Zhou ZX, Li Y (2019) Enhanced 2, 4-dichlorophenol degradation at pH 3-11 by peroxymonosulfate via controlling the reactive oxygen species over Ce substituted 3D Mn 2 O 3 . Chem Eng J 355:448–456

Ciardelli G, Corsi L, Marcucci M (2000) Membrane separation for wastewater reuse in the textile industry. Resour Conserv Recycl 31:189–197

Beavis P, Lundie S (2003) Integrated environmental assessment of tertiary and residuals treatment- LCA in the wastewater industry. Water Sci Technol 47:109–116

Shuval H, Lampert Y, Fattal B (1997) Development of a risk assessment approach for evaluating wastewater reuse standards for agriculture. Water Sci Technol 35:15–20

Levine AD, Asano T (2004) Recovering sustainable water from wastewater. Environ Sci Technol 38:201–208

Meneses M, Pasqualino JC, Castells F (2010) Environmental assessment of urban wastewater reuse: treatment alternatives and applications. Chemosphere 81:266–272

Pasqualino JC, Meneses M, Abella M, Castells F (2009) LCA as a decision support tool for the environmental improvement of the operation of a municipal wastewater treatment plant. Environ Sci Technol 43:3300–3307

Munoz I, Rodriguez A, Rosal R, Fernandez-Alba AR (2009) Life cycle assessment of urban wastewater reuse with ozonation as tertiary treatment: a focus on toxicity-related impacts. Sci Total Environ 407:1245–1256

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Tian, N., Nie, Y., Tian, X., Wang, Y. (2021). Current Water Treatment Technologies: An Introduction. In: Kharissova, O.V., Torres-Martínez, L.M., Kharisov, B.I. (eds) Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications. Springer, Cham. https://doi.org/10.1007/978-3-030-36268-3_75

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Modern Methods of Water Purification

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A special issue of Water (ISSN 2073-4441). This special issue belongs to the section " Wastewater Treatment and Reuse ".

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At the present stage, there is a huge number of methods available for the purification of waste and natural waters. However, unfortunately, the problem of water purification has not been fully resolved. Modern methods of purification include the use of various sorption materials (nanostructures, sorbents from waste, biosorbents, plant sorbents, etc.), membrane technologies (ultra- and mesofiltration, reverse osmosis, etc.), phylomediation technologies using higher aquatic plants (Eichhornia, duckweed, limnophila, etc.) and much more. The development and application of innovative methods of water purification will allow solving a number of environmental problems associated not only with clean water and public health, but also with the state of the environment as a whole.

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MIT engineers make filters from tree branches to purify drinking water

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The interiors of nonflowering trees such as pine and ginkgo contain sapwood lined with straw-like conduits known as xylem, which draw water up through a tree’s trunk and branches. Xylem conduits are interconnected via thin membranes that act as natural sieves, filtering out bubbles from water and sap.

MIT engineers have been investigating sapwood’s natural filtering ability, and have previously fabricated simple filters from peeled cross-sections of sapwood branches, demonstrating that the low-tech design effectively filters bacteria.

Now, the same team has advanced the technology and shown that it works in real-world situations. They have fabricated new xylem filters that can filter out pathogens such as E. coli and rotavirus in lab tests, and have shown that the filter can remove bacteria from contaminated spring, tap, and groundwater. They also developed simple techniques to extend the filters’ shelf-life, enabling the woody disks to purify water after being stored in a dry form for at least two years.

The researchers took their techniques to India, where they made xylem filters from native trees and tested the filters with local users. Based on their feedback, the team developed a prototype of a simple filtration system, fitted with replaceable xylem filters that purified water at a rate of one liter per hour.

Their results, published today in Nature Communications , show that xylem filters have potential for use in community settings to remove bacteria and viruses from contaminated drinking water.

The researchers are exploring options to make xylem filters available at large scale, particularly in areas where contaminated drinking water is a major cause of disease and death. The team has launched an open-source website , with guidelines for designing and fabricating xylem filters from various tree types. The website is intended to support entrepreneurs, organizations, and leaders to introduce the technology to broader communities, and inspire students to perform their own science experiments with xylem filters.

“Because the raw materials are widely available and the fabrication processes are simple, one could imagine involving communities in procuring, fabricating, and distributing xylem filters,” says Rohit Karnik, professor of mechanical engineering and associate department head for education at MIT. “For places where the only option has been to drink unfiltered water, we expect xylem filters would improve health, and make water drinkable.”

Karnik’s study co-authors are lead author Krithika Ramchander and Luda Wang of MIT’s Department of Mechanical Engineering, and Megha Hegde, Anish Antony, Kendra Leith, and Amy Smith of MIT D-Lab.

Clearing the way

In their prior studies of xylem, Karnik and his colleagues found that the woody material’s natural filtering ability also came with some natural limitations. As the wood dried, the branches’ sieve-like membranes began to stick to the walls, reducing the filter’s permeance, or ability to allow water to flow through. The filters also appeared to “self-block” over time, building up woody matter that clogged the conduits.

Surprisingly, two simple treatments overcame both limitations. By soaking small cross-sections of sapwood in hot water for an hour, then dipping them in ethanol and letting them dry, Ramchander found that the material retained its permeance, efficiently filtering water without clogging up. Its filtering could also be improved by tailoring a filter’s thickness according to its tree type.

The researchers sliced and treated small cross-sections of white pine from branches around the MIT campus and showed that the resulting filters maintained a permeance comparable to commercial filters, even after being stored for up to two years, significantly extending the filters’ shelf life.

The researchers also tested the filters’ ability to remove contaminants such as E. coli and rotavirus — the most common cause of diarrheal disease. The treated filters removed more than 99 percent of both contaminants, a water treatment level that meets the “ two-star comprehensive protection ” category set by the World Health Organization.

“We think these filters can reasonably address bacterial contaminants,” Ramchander says. “But there are chemical contaminants like arsenic and fluoride where we don’t know the effect yet,” she notes.

Encouraged by their results in the lab, the researchers moved to field-test their designs in India, a country that has experienced the highest mortality rate due to water-borne disease in the world, and where safe and reliable drinking water is inaccessible to more than 160 million people.

Over two years, the engineers, including researchers in the MIT D-Lab, worked in mountain and urban regions, facilitated by local NGOs Himmotthan Society, Shramyog, Peoples Science Institute, and Essmart. They fabricated filters from native pine trees and tested them, along with filters made from ginkgo trees in the U.S., with local drinking water sources. These tests confirmed that the filters effectively removed bacteria found in the local water. The researchers also held interviews, focus groups, and design workshops to understand local communities’ current water practices, and challenges and preferences for water treatment solutions. They also gathered feedback on the design.

“One of the things that scored very high with people was the fact that this filter is a natural material that everyone recognizes,” Hegde says. “We also found that people in low-income households prefer to pay a smaller amount on a daily basis, versus a larger amount less frequently. That was a barrier to using existing filters, because replacement costs were too much.”

With information from more than 1,000 potential users across India, they designed a prototype of a simple filtration system, fitted with a receptacle at the top that users can fill with water. The water flows down a 1-meter-long tube, through a xylem filter, and out through a valve-controlled spout. The xylem filter can be swapped out either daily or weekly, depending on a household’s needs.

The team is exploring ways to produce xylem filters at larger scales, with locally available resources and in a way that would encourage people to practice water purification as part of their daily lives — for instance, by providing replacement filters in affordable, pay-as-you-go packets.

“Xylem filters are made from inexpensive and abundantly available materials, which could be made available at local shops, where people can buy what they need, without requiring an upfront investment as is typical for other water filter cartridges,” Karnik says. “For now, we’ve shown that xylem filters provide performance that’s realistic.”

This research was supported, in part, by the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) at MIT and the MIT Tata Center for Technology and Design.

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Press mentions, popular science.

MIT researchers have created a new filter from tree branches that could provide an inexpensive, biodegradable, low-tech option for water purification, writes Shaena Montanari for Popular Science . “We hope that our work empowers such people to further develop and commercialize xylem water filters tailored to local needs to benefit communities around the world,” says Prof. Rohit Karnik.

United Press International (UPI)

UPI reporter Brooks Hays writes that MIT researchers have created a new water filter from tree branches that can remove bacteria. “The filter takes advantage of the natural sieving abilities of xylem -- thin, interconnected membranes found in the sapwood branches of pine, ginkgo and other nonflowering trees,” writes Hays.

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Determining water quality

Pretreatment.

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water purification

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water purification , process by which undesired chemical compounds , organic and inorganic materials, and biological contaminants are removed from water . That process also includes distillation (the conversion of a liquid into vapour to condense it back to liquid form) and deionization ( ion removal through the extraction of dissolved salts). One major purpose of water purification is to provide clean drinking water. Water purification also meets the needs of medical, pharmacological, chemical, and industrial applications for clean and potable water. The purification procedure reduces the concentration of contaminants such as suspended particles, parasites, bacteria , algae , viruses , and fungi . Water purification takes place on scales from the large (e.g., for an entire city) to the small (e.g., for individual households).

Most communities rely on natural bodies of water as intake sources for water purification and for day-to-day use. In general, these resources can be classified as groundwater or surface water and commonly include underground aquifers , creeks, streams, rivers , and lakes . With recent technological advancements, oceans and saltwater seas have also been used as alternative water sources for drinking and domestic use.

Historical evidence suggests that water treatment was recognized and practiced by ancient civilizations. Basic treatments for water purification have been documented in Greek and Sanskrit writings, and Egyptians used alum for precipitation as early as 1500 bce .

In modern times, the quality to which water must be purified is typically set by government agencies. Whether set locally, nationally, or internationally, government standards typically set maximum concentrations of harmful contaminants that can be allowed in safe water. Since it is nearly impossible to examine water simply on the basis of appearance, multiple processes, such as physical, chemical, or biological analyses, have been developed to test contamination levels. Levels of organic and inorganic chemicals, such as chloride, copper , manganese , sulfates , and zinc , microbial pathogens, radioactive materials, and dissolved and suspended solids, as well as pH , odour, colour, and taste, are some of the common parameters analyzed to assess water quality and contamination levels.

Regular household methods such as boiling water or using an activated-carbon filter can remove some water contaminants. Although those methods are popular because they can be used widely and inexpensively, they often do not remove more dangerous contaminants. For example, natural spring water from artesian wells was historically considered clean for all practical purposes, but it came under scrutiny during the first decade of the 21st century because of worries over pesticides , fertilizers , and other chemicals from the surface entering wells. As a result, artesian wells were subjected to treatment and batteries of tests, including tests for the parasite Cryptosporidium .

Not all people have access to safe drinking water. According to a 2017 report by the United Nations (UN) World Health Organization (WHO), 2.1 billion people lack access to a safe and reliable drinking water supply at home. Eighty-eight percent of the four billion annual cases of diarrhea reported worldwide have been attributed to a lack of sanitary drinking water. Each year approximately 525,000 children under age five die from diarrhea, the second leading cause of death, and 1.7 million are sickened by diarrheal diseases caused by unsafe water, coupled with inadequate sanitation and hygiene.

Most water used in industrialized countries is treated at water treatment plants. Although the methods those plants use in pretreatment depend on their size and the severity of the contamination, those practices have been standardized to ensure general compliance with national and international regulations. The majority of water is purified after it has been pumped from its natural source or directed via pipelines into holding tanks. After the water has been transported to a central location, the process of purification begins.

In pretreatment, biological contaminants, chemicals, and other materials are removed from water. The first step in that process is screening, which removes large debris such as sticks and trash from the water to be treated. Screening is generally used when purifying surface water such as that from lakes and rivers. Surface water presents a greater risk of having been polluted with large amounts of contaminants. Pretreatment may include the addition of chemicals to control the growth of bacteria in pipes and tanks (prechlorination) and a stage that incorporates sand filtration , which helps suspended solids settle to the bottom of a storage tank.

Preconditioning, in which water with high mineral content (hard water) is treated with sodium carbonate (soda ash), is also part of the pretreatment process. During that step, sodium carbonate is added to the water to force out calcium carbonate , which is one of the main components in shells of marine life and is an active ingredient in agricultural lime. Preconditioning ensures that hard water , which leaves mineral deposits behind that can clog pipes, is altered to achieve the same consistency as soft water .

Prechlorination, which is often the final step of pretreatment and a standard practice in many parts of the world, has been questioned by scientists. During the prechlorination process, chlorine is applied to raw water that may contain high concentrations of natural organic matter. This organic matter reacts with chlorine during the disinfection process and can result in the formation of disinfection by-products (DBPs), such as trihalomethanes, haloacetic acids, chlorite , and bromate. Exposure to DBPs in drinking water can lead to health issues. Worries stem from the practice’s possible association with stomach and bladder cancer and the hazards of releasing chlorine into the environment .

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Research Article

Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS)

Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliation Redlands East Valley High School, Redlands, California, United States of America

• Bill B. Wang

• Published: September 28, 2021
• https://doi.org/10.1371/journal.pone.0257865
• Reader Comments

This study, based in San Bernardino County, Southern California, collected and examined tap water samples within the area to explore the feasibility of adopting non-industrial equipment and methods to reduce water hardness and total dissolved solids(TDS). We investigated how water quality could be improved by utilizing water boiling, activated carbon and sodium bicarbonate additives, as well as electrolysis methods. The results show that heating is effective at lower temperatures rather than long boils, as none of the boiling tests were lower than the original value. Activated carbon is unable to lower TDS, because it is unable to bind to any impurities present in the water. This resulted in an overall TDS increase of 3.5%. However, adding small amounts of sodium bicarbonate(NaHCO 3 ) will further eliminate water hardness by reacting with magnesium ions and improve taste, while increasing the pH. When added to room temperature tap water, there is a continuous increase in TDS of 24.8% at the 30 mg/L mark. The new findings presented in this study showed that electrolysis was the most successful method in eliminating TDS, showing an inverse proportion where an increasing electrical current and duration of electrical lowers more amounts of solids. This method created a maximum decrease in TDS by a maximum of 22.7%, with 3 tests resulting in 15.3–16.6% decreases. Furthermore, when water is heated to a temperature around 50°C (122°F), a decrease in TDS of around 16% was also shown. The reduction of these solids will help lower water hardness and improve the taste of tap water. These results will help direct residents to drink more tap water rather than bottled water with similar taste and health benefits for a cheaper price as well as a reduction on plastic usage.

Citation: Wang BB (2021) Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS). PLoS ONE 16(9): e0257865. https://doi.org/10.1371/journal.pone.0257865

Editor: Mahendra Singh Dhaka, Mohanlal Sukhadia University, INDIA

Received: June 22, 2021; Accepted: September 14, 2021; Published: September 28, 2021

Copyright: © 2021 Bill B. Wang. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: The author received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

The concentration of total dissolved solids(TDS) present in water is one of the most significant factors in giving water taste and also provides important ions such as calcium, magnesium, potassium, and sodium [ 1 – 3 ]. However, water with high TDS measurements usually indicates contamination by human activities, such as soil and agricultural runoff caused by irrigation, unregulated animal grazing and wildlife impacts, environmentally damaging farming methods such as slash and burn agriculture, and the overuse of nitrate-based fertilizer [ 4 , 5 ], etc. Around tourist areas as well as state parks, these factors will slowly add up over time and influence the water sources nearby [ 5 ]. Water that flows through natural springs and waterways with high concentrations of organic salts within minerals and rocks, or groundwater that originates from wells with high salt concentration will also result in higher particle measurements [ 6 ].

Water sources can be contaminated by substances and ions such as nitrate, lead, arsenic, and copper [ 7 , 8 ] and may cause many health problems related to heavy metal consumption and poisoning. Water reservoirs and treatments plants that do not consider water contamination by motor vehicles, as well as locations that struggle to provide the necessary components required for water treatment will be more prone to indirect contamination [ 9 – 11 ]. Many plants are effective in ensuring the quality and reduction of these contaminants, but often leave out the secondary considerations, The United States Environmental Protection Agency(US EPA)’s secondary regulations recommend that TDS should be below 500 mg/L [ 2 ], which is also supported by the World Health Organization(WHO) recommendation of below 600 mg/L and an absolute maximum of less than 1,000 mg/L [ 3 ]. These substances also form calcium or magnesium scales within water boilers, heaters, and pipes, causing excess buildup and drain problems, and nitrate ions may pose a risk to human health by risking the formation of N -nitroso compounds(NOC) and less public knowledge about such substances [ 12 – 15 ]. Nitrates can pose a non-carcinogenic threat to different communities, but continue to slip past water treatment standards [ 15 ]. Furthermore, most people do not tolerate or prefer water with high hardness or chlorine additives [ 16 ], as the taste changes tremendously and becomes unpreferable. Even so, TDS levels are not accounted for in mandatory water regulations, because the essential removal of harmful toxins and heavy metals is what matters the most in water safety. Some companies indicate risks in certain ions and alkali metals, showing how water hardness is mostly disregarded and is not as well treated as commercial water bottling companies [ 17 , 18 ].

In Southern California, water quality is not as well maintained than the northern counties as most treatment plants in violation of a regulation or standard are located in Central-Southern California [ 19 ], with southern counties having the largest number of people affected [ 20 ]. This study is focused on the Redlands area, which has had no state code violations within the last decade [ 21 ]. A previous study has analyzed TDS concentrations throughout the Santa Ana Basin, and found concentrations ranging from 190–600 ppm as treated wastewater and samples obtained from mountain sites, taking into account the urban runoff and untreated groundwater as reasons for elevated levels of TDS but providing no solution in helping reduce TDS [ 22 ]. Also, samples have not been taken directly through home water supplies, where the consumer is most affected. Other water quality studies in this region have been focused on the elimination of perchlorates in soil and groundwater and distribution of nitrates, but such research on chemicals have ceased for the last decade, demonstrated by safe levels of perchlorates and nitrates in water reports [ 23 , 24 ]. In addition to these studies, despite the improving quality of the local water treatment process, people prefer bottled water instead of tap water because of the taste and hardness of tap water [ 25 ]. Although water quality tests are taken and documented regularly, the taste of the water is not a factor to be accounted for in city water supplies, and neither is the residue left behind after boiling water. The residue can build up over time and cause appliance damage or clogs in drainage pipes.

This study will build upon previous analyses of TDS studies and attempt to raise new solutions to help develop a more efficient method in reducing local TDS levels, as well as compare current measurements to previous analyses to determine the magnitude to which local treatment plants have improved and regulated its treatment processes.

Several methods that lower TDS are reviewed: boiling and heating tap water with and without NaHCO₃, absorption by food-grade activated carbon [ 26 , 27 ], and battery-powered electrolysis [ 28 – 30 ]. By obtaining water samples and determining the difference in TDS before and after the listed experiments, we can determine the effectiveness of lowering TDS. The results of this study will provide options for residents and water treatment plants to find ways to maintain the general taste of the tap water, but also preserve the lifespan of accessories and pipelines. By determining a better way to lower TDS and treat water hardness, water standards can be updated to include TDS levels as a mandatory measurement.

Materials and methods

All experiments utilized tap water sourced from Redlands homes. This water is partially supplied from the Mill Creek (Henry Tate) and Santa Ana (Hinckley) Water Sheds/Treatment Plants, as well as local groundwater pumps. Water sampling and sourcing were done at relatively stable temperatures of 26.9°C (80.42°F) through tap water supplies. The average TDS was measured at 159 ppm, which is slightly lower than the reported 175 ppm by the City of Redlands. Permission is obtained by the author from the San Bernardino Municipal Water Department website to permit the testing procedures and the usage of private water treatment devices for the purpose of lowering water hardness and improving taste and odor. The turbidity was reported as 0.03 Nephelometric Turbidity Units (NTU) post-treatment. Residual nitrate measured at 2.3mg/L in groundwater before treatment and 0.2 mg/L after treatment and perchlorate measured at 0.9 μg/L before treatment, barely staying below the standard of 1 μg/L; it was not detected within post-treatment water. Lead content was not detected at all, while copper was detected at 0.15 mg/L.

For each test, all procedures were done indoors under controlled temperatures, and 20 L of fresh water was retrieved before each test. Water samples were taken before each experimental set and measured for TDS and temperature, and all equipment were cleaned thoroughly with purified water before and after each measurement. TDS consists of inorganic salts and organic material present in solution, and consists mostly of calcium, magnesium, sodium, potassium, carbonate, chloride, nitrate, and sulfate ions. These ions can be drawn out by leaving the water to settle, or binding to added ions and purified by directly separating the water and ions. Equipment include a 50 L container, 1 L beakers for water, a graduated cylinder, a stir rod, a measuring spoon, tweezers, a scale, purified water, and a TDS meter. A standard TDS meter is used, operated by measuring the conductivity of the total amount of ionized solids in the water, and is also cleaned in the same manner as aforementioned equipment. The instrument is also calibrated by 3 pH solutions prior to testing.All results were recorded for and then compiled for graphing and analysis.

Heating/Boiling water for various lengths of time

The heating method was selected because heat is able to break down calcium bicarbonate into calcium carbonate ions that are able to settle to the bottom of the sample. Four flasks of 1 L of tap water were each heated to 40°C, 50°C, 60°C, and 80°C (104–176°F) and observed using a laser thermometer. The heated water was then left to cool and measurements were made using a TDS meter at the 5, 10, 20, 30, and 60-minute marks.

For the boiling experiments, five flasks of 1 L of tap water were heated to boil at 100°C (212°F). Each flask, which was labeled corresponding to its boiling duration, was marked with 2, 4, 6, 10, and 20 minutes. Each flask was boiled for its designated time, left to cool under open air, and measurements were made using a TDS meter at the 5, 10, 20, 30, 60, and 120-minute marks. The reason that the boiling experiment was extended to 120 minutes was to allow the water to cool down to room temperature.

Activated carbon as a water purification additive

This test was performed to see if food-grade, powdered activated carbon had any possibility of binding with and settling out residual particles. Activated carbon was measured using a milligram scale and separated into batches of 1, 2, 4, 5, 10, 30, and 50 mg. Each batch of the activated carbon were added to a separate flask of water and stirred for five minutes, and finally left to settle for another five minutes. TDS measurements were recorded after the water settled.

Baking soda as a water purification additive

To lower scale error and increase experimental accuracy, a concentration of 200 mg/L NaHCO₃ solution was made with purified water and pure NaHCO₃. For each part, an initial TDS measurement was taken before each experiment.

In separate flasks of 1 L tap water, each labeled 1, 2, 4, 5, 10, and 30 mg of NaHCO 3 , a batch was added to each flask appropriately and stirred for 5 minutes to ensure that everything dissolved. Measurements were taken after the water was left to settle for another 5 minutes for any TDS to settle.

Next, 6 flasks of 1 L tap water were labeled, with 5 mg (25 mL solution) of NaHCO₃ added to three flasks and 10 mg (50 mL solution) of NaHCO₃ added to the remaining three. One flask from each concentration of NaHCO₃ was boiled for 2 mins., 4 mins., or 6 mins., and then left to cool. A TDS measurement was taken at the 5, 10, 20, 30, 60, and 120-minute marks after removal from heat.

Electrolysis under low voltages

This test was performed because the ionization of the TDS could be manipulated with electricity to isolate an area of water with lower TDS. For this test, two 10cm long graphite pieces were connected via copper wiring to a group of batteries, with each end of the graphite pieces submerged in a beaker of tap water, ~3 cm apart.

Using groups of 1.5 V double-A batteries, 4 beakers with 40mL of tap water were each treated with either 7.5, 9.0, 10.5, and 12.0 V of current. Electrolysis was observed to be present by the bubbling of the water each test, and measurements were taken at the 3, 5, 7, and 10 minute marks.

Results/Discussion

Heating water to various temperatures until the boiling point.

The goal for this test was to use heat to reduce the amount of dissolved oxygen and carbon dioxide within the water, as shown by this chemical equation: Heat: Ca(HCO 3 ) 2 → CaCO 3 ↓ + H 2 O + CO 2 ↑.

This would decompose ions of calcium bicarbonate down into calcium carbonate and water and carbon dioxide byproducts.

Patterns and trends in decreasing temperatures.

The following trend lines are based on a dataset of changes in temperature obtained from the test results and graphed as Fig 1 .

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

https://doi.org/10.1371/journal.pone.0257865.g001

To predict the precise temperature measurements of the tap water at 26.9°C, calculations were made based on Fig 1 . The fitting equations are in the format, y = a.e bx . The values for the fitting coefficients a and b, and correlation coefficient R 2 are listed in Table 1 as column a, b and R 2 . The calculated values and the target temperature are listed in Table 1 .

https://doi.org/10.1371/journal.pone.0257865.t001

Fig 2 was obtained by compiling TDS results with different temperatures and times.

https://doi.org/10.1371/journal.pone.0257865.g002

The fitting equations for Fig 2 are also in the format, y = a.e bx . The fitting coefficients a and b, and correlation coefficient R 2 values are listed in Table 2 . Based on the fitting curves in Fig 2 and the duration to the target temperature in Table 1 , We calculated the TDS at 26.9°C as listed in column calculated TDS in Table 2 based on the values we reported on Fig 2 .

https://doi.org/10.1371/journal.pone.0257865.t002

Based on the heating temperature and the calculated TDS with the same target water temperature, we obtained the following heating temperature vs TDS removal trend line and its corresponding fitting curve in Table 2 .

In Fig 1 , a trend in the rate of cooling is seen, where a higher heating temperature creates a steeper curve. During the first five minutes of cooling, the water cools quicker as the absorbed heat is quickly released into the surrounding environment. By the 10-minute mark, the water begins to cool in a linear rate of change. One detail to note is that the 100°C water cools quicker than the 80°C and eventually cools even faster than the 60°C graph. Table 1 supports this observation as the duration to target temperature begins to decrease from a maximum point of 94.8 mins to 80.95 mins after the 80°C mark.

As shown in Fig 2 , all TDS values decrease as the temperature starts to cool to room temperature, demonstrating a proportional relationship where a lower temperature shows lower TDS. This can partially be explained by the ions settling in the flasks. Visible particles can also be observed during experimentation as small white masses on the bottom, as well as a thin ring that forms where the edge of the water contacts the flask. When the water is heated to 40°C and cooled, a 3.8% decrease in TDS is observed. When 50°C is reached, the TDS drops at its fastest rate from an initial value of 202 ppm to 160 ppm after 60 minutes of settling and cooling. The TDS measurements in these experiements reach a maximum of 204 ppm at the 60°C mark. However, an interesting phenomenon to point out is that the water does not hit a new maximum at 100°C. meaning that TDS reaches a plateau at 60°C. Also, the rate of decrease begins to slow down after 20 minutes, showing that an unknown factor is affecting the rate of decrease. It is also hypothesized that the slight increase in TDS between the 5–20 minute range is caused by a disturbance in the settling of the water, where the temperature starts to decrease at a more gradual and constant rate. The unstable and easy formation of CaCO 3 scaling has also been the subject of a study of antiscaling methods, which also supports the result that temperature is a significant influence for scale formation [ 12 ].

In Table 2 , calculations for TDS and the time it takes for each test to cool were made. Using the data, it is determined that the test with 50°C water decreased the most by 16% from the initial measurement of 159ppm. This means that it is most effective when water is heated between temperatures of 40–60°C when it comes to lowering TDS, with a difference of ~7–16%. When water is heated to temperatures greater than 80°C, the water begins to evaporate, increasing the concentration of the ions, causing the TDS to increase substantially when cooled to room temperature.

Finally, in Fig 3 , a line of best fit of function f(x) = -0.0007x 3 + 0.1641x 2 –10.962x + 369.36 is used with R 2 = 0.9341. Using this function, the local minimum of the graph would be reached at 48.4°C.

https://doi.org/10.1371/journal.pone.0257865.g003

This data shows that heating water at low temperatures (i.e. 40–50°C) may be more beneficial than heating water to higher temperatures. This study segment has not been presented in any section within the United States EPA Report on water management for different residual particles/substances. However, warmer water temperatures are more prone to microorganism growth and algal blooms, requiring more intensive treatment in other areas such as chlorine, ozone, and ultraviolet disinfection.

Using the specific heat capacity equation, we can also determine the amount of energy and voltage needed to heat 1 L of water up to 50°C: Q = mcΔT, where c, the specific heat capacity of water, is 4.186 J/g°C, ΔT, the change in temperature from the experimental maximum to room temperature, is 30°C, and m, the mass of the water, is 1000 g. This means that the amount of energy required will be 125580 J, which is 0.035 kWh or 2.1 kW.

After taking all of the different measurements obtained during TDS testing, and compiling the data onto this plot, Fig 4 is created with a corresponding line of best fit:

https://doi.org/10.1371/journal.pone.0257865.g004

In Fig 4 , it can be observed that the relationship between the temperature of the water and its relative TDS value is a downwards facing parabolic graph. As the temperature increases, the TDS begins to decrease after the steep incline at 50–60°C. The line of best fit is represented by the function f(x) = -0.0142x 2 + 2.258x + 105.84. R 2 = 0.6781. Because the R 2 value is less than expected, factors such as the time spent settling and the reaction rate of the ions should be considered. To determine the specifics within this experiment, deeper research and prolonged studies with more highly accurate analyses must be utilized to solve this problem.

Boiling water for various amounts of time

Trend of boiling duration and rate of cooling..

Using the same methods to create the figures and tables for the previous section, Fig 5 depicts how the duration of time spent boiling water affects how fast the water cools.

https://doi.org/10.1371/journal.pone.0257865.g005

As seen in Fig 5 , within the first 10 minutes of the cooling time, the five different graphs are entwined with each other, with all lines following a similar pattern. However, the graph showing 20 minutes of boiling is much steeper than the other graphs, showing a faster rate of cooling. This data continues to support a previous claim in Fig 2 , as this is most likely represented by a relationship a longer the boil creates a faster cooling curve. This also shows that the first 5 minutes of cooling have the largest deviance compared to any other time frame.

The cooling pattern is hypothesized by possible changes in the orderly structure of the hydrogen bonds in the water molecules, or the decreased heat capacity of water due to the increasing concentration of TDS.

Effect on TDS as boiling duration increases.

In Fig 6 , all lines except for the 20-minute line are clustered in the bottom area of the graph. By excluding the last measurement temporarily due to it being an outlier, we have observed that the difference between the initial and final TDS value of each test decreases.

https://doi.org/10.1371/journal.pone.0257865.g006

Despite following a similar trend of an increase in TDS at the start of the tests and a slow decrease overtime, this experiment had an interesting result, with the final test measuring nearly twice the amount of particles compared to any previous tests at 310 ppm, as shown in Fig 6 . It is confirmed that the long boiling time caused a significant amount of water to evaporate, causing the minerals to be more concentrated, thus resulting in a 300 ppm reading. Fig 6 follows the same trend as Fig 2 , except the TDS reading veers away when the boiling duration reaches 20 minutes. Also, with the long duration of heating, the water has developed an unfavorable taste from intense concentrations of CaCO₃. This also causes a buildup of a thin crust of CaCO₃ and other impurities around the container that is difficult to remove entirely. This finding is in accordance with the introductory statement of hot boiling water causing mineral buildups within pipes and appliances [ 9 ]. A TDS reading of 300ppm is still well below federal secondary standards of TDS, and can still even be compared to bottled water, in which companies may fluctuate and contain 335ppm within their water [ 1 , 2 ].

This experiment continues to stupport that the cooling rate of the water increases as the time spent boiling increases. Based on this test, a prediction can be made in which an increased concentration of dissolved solids lowers the total specific heat capacity of the sample, as the total volume of water decreases. This means that a method can be derived to measure TDS using the heat capacity of a tap water mixture and volume, in addition to current methods of using the electrical conductivity of aqueous ions.

Adding food-grade activated carbon to untreated tap water

Fig 7 presents a line graph with little to no change in TDS, with an initial spike from 157 to 163 ppm. The insoluble carbon remains in the water and shows no benefit.

https://doi.org/10.1371/journal.pone.0257865.g007

The food-grade activated carbon proved no benefit to removing TDS from tap water, and instead added around 5–7 ppm extra, which settled down to around +4 ppm at 120 minutes. The carbon, which is not 100% pure from inorganic compounds and materials present in the carbon, can dissolve into the water, adding to the existing concentration of TDS. Furthermore, household tap water has already been treated in processing facilities using a variety of filters, including carbon, so household charcoal filters are not effective in further reducing dissolved solids [ 18 ].

Adding sodium bicarbonate solution to boiled tap water

As seen in Fig 8 , after adding 1 mg of NaHCO 3 in, the TDS rises to 161 ppm, showing a minuscule increase. When 4 mg was added, the TDS drops down to 158 ppm. Then, when 5 mg was added, a sudden spike to 172 ppm was observed. This means that NaHCO 3 is able to ionize some Ca 2+ and Mg 2+ ions, but also adds Na + back into the water. This also means that adding NaHCO 3 has little to no effect on TDS, with 4mg being the upper limit of effectiveness.

https://doi.org/10.1371/journal.pone.0257865.g008

To examine whether or not the temperature plays a role in the effectiveness in adding NaHCO 3 , a boiling experiment was performed, and the data is graphed in Fig 9 .

https://doi.org/10.1371/journal.pone.0257865.g009

Fig 9 presents the relationship between the amount of common baking soda(NaHCO₃) added, the boiling time involved, and the resulting TDS measurements. After boiling each flask for designated amounts of time, the results showed a downward trend line from a spike but does not reach a TDS value significantly lower than the initial sample. It is apparent that the NaHCO₃ has not lowered the TDS of the boiling water, but instead adds smaller quantities of ions, raising the final value. This additive does not contribute to the lowering of the hardness of the tap water. However, tests boiled with 5 mg/L of baking soda maintained a downward pattern as the water was boiled for an increasing amount of time, compared to the seemingly random graphs of boiling with 10 mg/L.

In some households, however, people often add NaHCO₃ to increase the pH for taste and health benefits. However, as shown in the test results, it is not an effective way of reducing TDS levels in the water [ 10 , 16 ], but instead raises the pH, determined by the concentration added. Even under boiling conditions, the water continues to follow the trend of high growth in TDS, of +25–43 ppm right after boiling and the slow drop in TDS (but maintaining a high concentration) as the particles settle to the bottom.

Utilizing the experimental results, we can summarize that after adding small batches of NaHCO3 and waiting up to 5 minutes will reduce water hardness making it less prone to crystallizing within household appliances such as water brewers. Also, this process raises the pH, which is used more within commercial water companies. However, the cost comes at increasing TDS.

Using electrolysis to treat TDS in tap water

Different voltages were passed through the water to observe the change in TDS overtime, with the data being compiled as Fig 10 .

https://doi.org/10.1371/journal.pone.0257865.g010

The process of electrolysis in this experiment was not to and directly remove the existing TDS, but to separate the water sample into three different areas: the anode, cathode, and an area of clean water between the two nodes [ 19 ]. The anions in the water such as OH - , SO 4 2- , HCO 3 - move to the anode, while the cations such as H + , Ca 2+ 、Mg 2+ 、Na + move to the cathode. The middle area would then be left as an area that is more deprived of such ions, with Fig 10 proving this.

As shown in Fig 10 , electrolysis is effective in lower the TDS within tap water. Despite the lines being extremely tangled and unpredictable, the general trend was a larger decrease with a longer duration of time. At 10 minutes, all lines except 10.5 V are approaching the same value, meaning that the deviation was most likely caused by disturbances to the water during measurement from the low volume of water. With each different voltage test, a decrease of 12.7% for 6.0 V, 14.9% for 9.0 V, 22.7% for 10.5 V. and 19.5% for 12.0 V respectfully were observed. In the treatment of wastewate leachate, a study has shown that with 90 minutes of electrical treatment, 34.58% of TDS content were removed, supporting the effectiveness of electricity and its usage in wastewater treatment [ 29 ].

This experiment concludes that electrolysis is effective in lowering TDS, with the possibility to improve this process by further experimentation, development of a water cleaning system utilizing this cathode-anode setup to process water. This system would be a more specific and limited version of a reverse osmosis system by taking away ions through attraction, rather than a filter.

The Southern Californian tap water supply maintains TDS values below the federal regulations. However, crystalline scale buildup in household appliances is a major issue as it is hard to clean and eliminate. To easily improve the taste and quality of tap water at home as well as eliminating the formation of scales, the following methods were demonstrated as viable:

• By heating water to around 50°C (122°F), TDS and water hardness will decrease the most. Also, the boiling process is effective in killing microorganisms and removing contaminants. This process cannot surpass 10 minutes, as the concentration of the ions in the water is too high, which poses human health risks if consumed. These, along with activated carbon and NaHCO₃ additives, are inefficient methods that have minimal effects for lowering TDS.
• Electrolysis is one of the most effective methods of eliminating TDS. Experiments have proven that increased current and duration of time helps lower TDS. However, this method has yet to be implemented into conventional commercial water filtration systems.

Also, some observations made in these experiments could not be explained, and require further research and experimentation to resolve these problems. The first observation is that TDS and increasing water temperature maintain a parabolic relationship, with a maximum being reached at 80°C, followed by a gradual decrease. The second observation is that when water is boiled for an increased duration of time, the rate of cooling also increases.

This experiment utilized non-professional scientific equipment which are prone to mistakes and less precise. These results may deviate from professionally derived data, and will require further study using more advanced equipment to support these findings.

Acknowledgments

The author thanks Tsinghua University Professor and PLOS ONE editor Dr. Huan Li for assisting in experimental setups as well as data processing and treatment. The author also thanks Redlands East Valley High School’s Dr. Melissa Cartagena for her experimental guidance, and Tsinghua University Professor Dr. Cheng Yang for proofreading the manuscript.

• View Article
• Google Scholar
• 2. United States Environmental Protection Agency. 2018 Edition of the Drinking Water Standards and Health Advisories Tables (EPA 822-F-18-001). US EPA, Washington D.C., USA, 2018; pp. 9–19.
• 3. World Health Organization. Guidelines for Drinking-Water Quality: Fourth Edition Incorporating the First Addendum. WHO, Geneva, Switzerland, 2017; pp. 7, 219–230, 423.
• PubMed/NCBI
• 6. Chloride, Salinity, and Dissolved Solids. 2019 Mar 1, [cited on 20 September 2020] Available from: https://www.usgs.gov/mission-areas/water-resources/science/chloride-salinity-and-dissolved-solids?qt-science_center_objects=0#qt-science_center_objects .
• 13. Shoukat, Ammara, Hussain, M., Shoukat, Asra. Effects of Temperature on Total dissolved Solid in water. Water Quality Study Conference, Mehran University Sindh, Pakistan, February 2020.
• 17. United States Environmental Protection Agency. Drinking Water Treatment Plant Residuals Management—Technical Report: Summary of Residuals Generation, Treatment, and Disposal at Large Community Water Systems. US EPA, Washington D.C., USA, 2011; pp. 177–182.
• 19. Exceedance and Compliance Status of Public Water Systems. 2012 Feb 1, [cited 22 September 2020] Available from: https://www.arcgis.com/apps/MapJournal/index.html?appid=143794cd74e344a29eb8b96190f4658b# .
• 20. 2019 Water Quality Status Report California. California Water Boards, 2019 July 1, [cited 22 September 2020] Available from: https://gispublic.waterboards.ca.gov/portal/apps/MapJournal/index.html?appid=6cde29ac0afc4d55b0fdaaae6bfc1aa4 .
• 21. City of Redlands—Water Quality Consumer Confidence Reports. City of Redlands, 2010–2020, [cited 23 September 2020] Available from: https://www.cityofredlands.org/post/water-quality .
• 25. Consumers’ Preference For Bottled Water Is Growing And They Want It Available Wherever Drinks Are Sold. 2019 Jan 8, [cited 23 September 2020] Available from: https://www.bottledwater.org/consumers’-preference-bottled-water-growing-and-they-want-it-available-wherever-drinks-are-sold .

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• Published: 06 July 2020

Public health benefits of water purification using recycled hemodialyzers in developing countries

• Jochen G. Raimann   ORCID: orcid.org/0000-0002-8954-2783 1 , 2 , 3 , 4 ,
• Joseph Marfo Boaheng 4 , 5 ,
• Philipp Narh 4 , 6 ,
• Harrison Matti 4 ,
• Seth Johnson 1 , 4 ,
• Linda Donald 1 , 4 ,
• Hongbin Zhang 7 , 8 ,
• Friedrich Port 1 , 9 &
• Nathan W. Levin 1 , 4  

Scientific Reports volume  10 , Article number:  11101 ( 2020 ) Cite this article

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In rural regions with limited resources, the provision of clean water remains challenging. The resulting high incidence of diarrhea can lead to acute kidney injury and death, particularly in the young and the old. Membrane filtration using recycled hemodialyzers allows water purification. This study quantifies the public health effects. Between 02/2018 and 12/2018, 4 villages in rural Ghana were provided with a high-volume membrane filtration device (NuFiltration). Household surveys were collected monthly with approval from Ghana Health Services. Incidence rates of diarrhea for 5-month periods before and after implementation of the device were collected and compared to corresponding rates in 4 neighboring villages not yet equipped. Data of 1,130 villagers over 10 months from the studied communities were studied. Incidence rates showed a decline following the implementation of the device from 0.18 to 0.05 cases per person-month (ppm) compared to the control villages (0.11 to 0.08 ppm). The rate ratio of 0.27 for the study villages is revised to 0.38 when considering the non-significant rate reduction in the control villages. Provision of a repurposed hemodialyzer membrane filtration device markedly improves health outcomes as measured by diarrhea incidence within rural communities.

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Introduction.

Estimates from the World Health Organization and the World Bank place around 1.1 billion people in the world in a position of having to drink unsafe water. Water and sanitation, specifically access to clean water for the world population, were adopted as the Sustainable Development Goal-6 (SDG-6) by all member states of the United Nations. The deserved, widespread attention emphasizes the importance of the issue and the need for more improvement. Industrialized countries have to a large extent solved the problem and a majority of their populations has access to safe drinking water. This is mainly due to the effort of governments, strict laws, regular monitoring, efficient handling and cleaning of sewage, centralized and monitored provision of clean drinking water and lastly to a generally higher level of hygiene (including the use and provision of sanitary facilities). Due to high population growth rates, lack of economic development, and inadequate political efforts this remains a major problem in many countries with limited resources.

Rural areas in developing countries present problems of greatest magnitude. Water is still mainly carried from continually contaminated surface water such as ponds and rivers. Water is often polluted by coliform bacteria and viral pathogens. Factors such as a lack of sanitary facilities, inadequate hygiene practices and substantial flooding during rainy seasons aggravate the problem. Not only surface but also centralized, processed water are at high probability of being contaminated 1 . Wells may also be susceptible to pollution particularly when they are shallow or intermittently overcome by raising water tables. Further, in some low-income countries a flourishing business of sachet water exists, which is assumed to be safe for consumption. However, as shown in work from Nigeria these sachets are also in many cases contaminated due to improper packaging and storage, or inadequate hygiene in the processing. The incidence of diarrhea and its life threatening complications such as dehydration and acute kidney injury correlate with these factors 2 . Non-infectious contaminants in drinking water such as lead and other heavy metals, arsenic, and also organophosphates from pesticides and insecticides contribute to health hazards, problems that are not addressed with our work at present.

Since the first epidemiological studies by the physician John Snow in the nineteenth century, the deleterious effect of microbial pathogens in water has been well established. Estimates of the World Health Organization suggest that 88% of all diarrheal diseases are caused by the consumption of unsafe drinking water and the lack of adequate sanitation facilities 3 . A recent publication of the initiative has identified that a majority of cases of acute kidney injury in the developing world are (in contrast to the most frequently reported pathogenesis in first world countries) are associated with community-acquired disease and to a major part with diarrhea 4 . This is particularly evident in children 2 to 5 years of age in whom mortality is very high 5 . Overall, these data strongly corroborate why it must be a prime goal for the world community to jointly aim to achieve the SDG-6. These data provide a powerful stimulus for widespread joint action by the world community to achieve this goal.

Common approaches to counteract microbial pollution include various filtration devices: Microfiltration, ultrafiltration, nanofiltration and reverse osmosis. Membrane filtration has long been recognized as an effective and likely efficient approach to partly solve the problem in rural regions, however membranes and filtration devices are expensive, and filters are prone to clogging without proper functioning flushing methodologies. The great need that is also building the basis of the SDG-6 of the United Nations, will require an affordable solution to be made available that is not overly prone to malfunction, can sustain functionality over a long period of time and does not require too extensive maintenance in terms of parts and labor. Surface water is often polluted with parasites, bacteria and viruses that can cause serious health issues 6 . Of note, all these pathogens are larger than the pore size of the hemodialyzer that is approximately 0.003 µm. This pore size notably is smaller than most commercially available purification devices, the operation of which has been claimed to be a feasible technique for water purification 2 .

Hemodialysis is a renal replacement therapy modality that uses hemodialyzers in those suffering from renal failure to counteract the consequences of not having kidney function and to ultimately save them from dying. These hemodialyzers are mainly comprised hollow fibers in a plastic casing. This allows, after cannulation of the patient, to pass the patient’s blood inside the fibers, and along the semipermeable membrane of the fiber, until it leaves the hemodialyzer and is returned to the patient. At the same time, dialysis water, containing anions and cations in specifically defined concentrations, passes, in a countercurrent fashion, on the other side of the membrane resulting in gradient-driven diffusion allowing for toxin removal from the blood and by producing a hydrostatic pressure also removes excess water from the patient through volumetric ultrafiltration. These hemodialyzers were commonly being reused after sterilization, a practice that has changed since earlier days of dialysis and current clinical practice commonly uses hemodialyzers only once and discards them after use. Of note, this alone results in approximately 30 kg of annual waste for every (out of approximately 2 million worldwide) dialysis patient 7 . It was shown recently that used and re-sterilized hemodialyzers (a process possible at less than $2 per hemodialyzer) are effective in producing clean water from microbiologically contaminated water when pushed through these hemodialyzers under high hydrostatic pressure.

We, Easy Water for Everyone (EWfE), report here the experience and some preliminary data from the use of this relatively simple technique for preparation of drinking water from polluted river water in rural villages in Ghana that have no electricity. We provided villages with devices containing re-sterilized hemodialyzers uniquely repurposed from their hemodialysis past, which are capable of producing large volumes of water (up to 500 L/h) free of bacteria and viruses for domestic use. Here we report public health outcomes based on prospectively collected self-reported public health information on diarrhea incidence collected before and after implementation of this device in several villages.

Material and methods

Easy Water for Everyone (EWfE) is a 501(c)(3) non-profit, non-governmental organization (NGO) in the United States, Ghana (and with other countries in progress). With the help of local politicians and stakeholders a need for water purification in the estuary of the Volta River in Ghana was identified. For those living in this region the river is the main source for drinking water even though it is known to carry pathogens. Under the supervision of local committees and administrators, EWfE started to install and maintain a device in each of the villages. The chronological order was arbitrary and data collection was commenced on the islands around Ada Foah since 02/2018.

Water purification method

The membrane filtration device (NUF500; NUFiltration, Israel), consists of a set of 8 hollow-fiber hemodialyzers, appropriate tubings and a faucet. These hollow fiber hemodialyzers in this project have been used as hemodialyzers once, then reprocessed and sterilized according to FDA/AAMI standards before installation into the water-purification device. Each hemodialyzer contains around 12,000 capillaries providing a membrane surface area of nearly 2 square meters per hemodialyzer. The membrane pore size is 0.003 µm, notably preventing passage of bacteria, parasites and notably also of pathogenic viruses. The output of pure water can be as high as 500 L/h when actively pumped into the device or up to 250 L/h passed into the device by gravity after being pumped into an overhead tank as used in this study. The pressure by gravity is caused by a height of about 12 feet from which the polluted water enters the eight dialyzers placed in parallel (see Fig.  1 a, b).

Hemodialyzer membrane filtration device used for our project. Setting with ( a ) a manual pump (up to 500 L/h) and ( b ) gravitational force (up to 250 L/h) for driving the contaminated into the re-sterilized and repurposed hemodialyzer filters.

Contaminated river water enters the inside of the capillaries (“blood” compartment) while clean water collects outside of the capillaries (“dialysate” compartment in clinical hemodialysis). Only water (and dissolved salts) passes through the pores. Organic matter that accumulates on the inside of the capillary fibers needs to be rinsed away by intermittently reversing the pressures and filtering clean water back across the membranes (backwashing) through manual pumping. It takes less than 5 min for the backflow to change from dirty to clean appearance and then regain full efficiency for providing clean water.

Data collection

Following the approval of our research project, embedded in the non-profit endeavor, by Ghana Health Services, we initiated data collection with trained local community members to support our endeavor. Next to demographic data and water results before and after passing through the filter, we collected data monthly from the heads of households on self-reported diarrhea events in 8 villages during the months February through November 2018. This was a subset of villages served by EWfE.

In late June 2018, the hemodialyzer filtration devices became operational in 4 of these villages so that this ongoing monthly data collection started 5 months before the installation. It was concluded 5 months after the installation of the hemodialyzer filtration device. Simultaneously the same data was collected in the 4 villages without the device. For each village and each month, the count of diarrhea events and the number of persons exposed to the data collection were analyzed to estimate the monthly diarrhea incidence rates. Monthly data were summarized for each of the two groups of villages, the control group of 4 villages never exposed to the hemodialyzer water treatment and the group of 4 villages exposed to the water treatment during their second 5 months of the 10-months study period. This approach allowed comparison of the incidence rates during the first and second 5-months periods and incidence rate ratios (second/first 5 months) for the study group and the control group. Having this concomitant data allows us, in a univariate fashion, to use village populations as their own controls and consider the potential confounding effect of seasonality.

The results of water testing showed coliform bacteria at 558 CFU/100 mL in the source water (Volta River) and zero CFU in the filtrate water at the beginning of our installations in the villages of Big Ada. We studied 8 villages (4 were designated control villages and 4 were study villages) in rural Ghana. Table 1 shows the population characteristics of the study arms. Of the village populations studied in this cohort study, 11% and 8% were younger than 5 years of age and notably showed a remarkably high proportion of villagers (96% and 99%) had to resort to open defecation.

Monthly diarrhea incidence rates averaged 0.18 counts per exposure month during the baseline period of the study villages and 0.11 for the same 5 months of the control group. During the first 5 months after the installation of the hemodialyzer filtration device, the rate reduced to 0.05, yielding a rate ratio for the study group of 0.28. For the control group the second 5 months gave an average rate of 0.08, showing modest non-significant reduction from the prior 5 months period with a rate ratio of 0.73 (Table 2 ). Figure  2 a and b show the monthly data for the two periods in both village groups. The control villages of the same region and during the same calendar months allow consideration of a seasonal effect on the diarrhea incidence in the study group. Thus, using the incidence rate ratio for the second 5 months over the first 5 months gives a seasonally adjusted rate ratio of 0.38 (0.28/0.73), which translates to a diarrhea incidence rate that is reduced by 62% following initiation of the hemodialyzer filtration device in the study villages.

Monthly diarrhea incidence rates between February (Month − 5) and November (Month + 5) 2018 in ( a ) study villages, where the device was installed in late June 2018 and ( b ) control villages with no device installation during the same months.

In many countries microbiologically contaminated water is the underlying cause of gastrointestinal disease, mainly diarrhea, associated with deleterious consequences such as acute kidney injury resulting in a high mortality rate, particularly in weaned children younger than five and the elderly. Our data, collected in 4 rural communities in the Ada-East distric of Greater Accra Region in Ghana, before and after the implementation of a hemodialyzer membrane filtration device to produce clean drinking water, shows a substantially reduced risk (rate) of self-reported diarrhea by 72%. This is a major public health outcome particularly since diarrhea is well known to be associated with deleterious consequences such as acute kidney injury and death, particularly in younger children and the elderly. This finding is striking and the rigorous analytic design where each community serves as their own control allows for drawing solid conclusions. Studying and comparing our data to that of a control group which presented only with modest reduction in the incidence of diarrhea over the same time period, corroborates an effect that can be attributed to implementation of our approach. The only modest reduction of diarrhea incidence in the control villages also reduces concerns of seasonality in the incidence rates confounding our interpretation.

Discussion of our approach in comparison with other approaches

The methods used in the present study have been effective in removing pathogens from consistently polluted river or lake water sources. During the past 3 years the on-site implementation of the hemodialyzer filtration device have allowed us to demonstrate the success of providing clean and pathogen-free drinking water to villages where the source of drinking water had been consistently contaminated. This system works well even in remote areas without requiring electricity or other external power sources. No restrictions on water use need to be imposed and use of clean water can be encouraged also for handwashing with soap. When more water is needed, the filling of the main water tank can be increased from weekly to two to three times a week (or even daily). There are several key elements that contrast our approach to other methods to produce drinking water: (1) Rejection of pathogens is highly effective and includes particles as small as pathogenic viruses, given the pore size of 0.003 µm, (2) no need to add bactericidal agents such as chlorine to kill remaining pathogens in drinking water, (3) the simplicity of this design allows its use in isolated rural villages even in areas that have no electricity, (4) this system becomes almost self-sufficient after a few villagers have been trained to do the thrice daily backwashing, (5) excellent filtration rates have been observed with this setup for over one year, (6) visits by a trained technician once or twice weekly or more frequently when necessary for refilling the large water tanks using a gas-driven pump provide some monitoring of the continued function and service and (7) relatively low cost since the reprocessed hemodialyzers are inexpensive and have shown in our 3-year experience to maintain high output rates of nearly 250 L/h (by gravity feed) for over one year. Furthermore, in circumstances where larger volumes of purified water are needed, an expanded device, employing far more dialyzers could be utilized. It would also be feasible to equip the device with solar panels which would increase water production substantially but would add to the cost.

Comparison of efficacy with other approaches

Attempts to purify water from microbiological contamination have been undertaken in a multitude of studies discussing purification of water from springs, boreholes, and wells, all sources with many opportunities for contamination to occur between sources and point of use. The source water is detoxified and infectious agents are reduced or removed by methods such as chlorination, membrane filtration, flocculation and others. Direct systems include conventional filtration, for example using sand through granular media which removes parasites, bacteria and possibly some viruses. Conventional filtration also includes chemical coagulants such as potassium alum added to source water which produce clots (flocs) which are in turn filtered. These processes are not easy and require expert handling by trained individuals.

Quite commonly reported is household chlorination which is a simple technique with widespread use. It improves water quality and effectively prevent diarrheal diseases. Quantity and acceptance (because of the resultant taste of the water) are downsides of this approach 5 .

With direct filtration, water passes through a medium such as sand or diatomaceous earth, a process which removes giardia lamblia, cryptosporidia, and bacteria from the water. These methods also remove color and turbidity. Filtration bags are warm bags or cartridges containing a filament to strain the water. These bags are however not useful for anything smaller than the giardia. Ceramics may be impregnated with tiny colloidal particles and allows for eradication of most bacteria and protozoan parasites. However, also this method is not adequate for virus removal. Most of these methods however are laborious, require specialized knowledge and infrastructure, and also time.

Membranes are widely used to produce safe drinking water and are the only means available to produce water free of parasites, bacteria and all pathogenic viruses.

Membranes can be divided into groups largely defined by their characteristics in regard to pore sizes. Depending on the degree of pore size, they can also produce water free of many chemical components. In the case of biologically contaminated water some membranes can produce water free of bacteria, parasites and viruses.

Hemodialyzers that are contained in the device we have chosen to implement in village structures have a semi-permeable membrane made of polysulphone and polyethersulphone. The pore size is around 0.003 µm and will not let parasites, bacteria and viruses pass, while still providing an output as large as 500 L/h.

Decreased microbial quantity in drinking water is effective in decreasing diarrhea. Effectiveness does not solely depend on the presence of improved water supplies but will also be affected by the use of sanitization facilities and handwashing with diligent soap procedures. In concert with appropriate education, these interventions will play a powerful role in improving public health outcomes. Also important in the context of effectiveness is the amount of water that is being produced over a defined period of time. In this context it is of note that our approach, even with the use of the gravitational device where water is pumped into an overhead tank and gravitation is being used to transfer contaminated water into the filter, allows for up to 250 L/h.

Household efforts

Household efforts include: improved water storage, chlorination, solar exposure, filtration by filter media in relationship to pore size, combined flocculation and disinfection methods. A combination of efforts including improved water supply and storage, and improved sanitation results in better water supplies thus reducing the risk of developing diarrhea. Various authors provide a range of figures for reduction of diarrhea but overall it is expected that household interventions will provide a risk reduction for diarrhea incidence 8 . The WHO promotes water treatment and safe storage of household water. Affordability, acceptability, sustainability and scale ability are all important factors and these small-scale solutions do provide improvement.

A current technology comparable to our approach are the “Aqua Towers”, an approach that also uses gravitational forces to pass water through the filter. More than 1,000 of these are active in Asia Pacific and Latin America. It utilizes ultrafiltration but the manufacturer does not reveal the membrane type. Activated carbon is used to enhance the quality of the drinking water. In addition, part of the water supply is used for hand washing. The authors claim that viruses larger than 0.01 microns are removed. However, a membrane with pore sizes as large will not exclude the rotavirus (a causative pathogen of diarrhea in up to 40% in some reported populations), and hepatitis B and C viruses, unlike the hollow fiber hemodialyzer membrane as discussed above. Of note, no outcome data have been published for the communities using the “Aqua Towers”, to the best of our knowledge.

Strengths and limitations of our study

Surveys of diarrhea in households may be considered soft data, however the magnitude of a relative 72% reduction in the incidence of diarrhea per monitored population is strikingly large. It is also corroborated by many mothers reporting a sudden virtual absence of diarrhea in their children after availability of the hemodialyzer-filtered water. The marked reduction in the diarrhea incidence may be due to using sterile water instead of river water polluted with known pathogens, such as E. coli , as the main source of drinking water. Additionally, handwashing with clean water may be an important contributor to our observations. While our study cannot prove causation with certainty, the nearly stable rates in the control group suggests a causative role of the change in the water source from river water to filter-sterilized water.

Of note, we decided to not adjust for population characteristics for two reasons: the same population served as their own controls for each household and the groups of villages and secondly the incidence rates during the initial 5 months were similar for the two groups of villages.

Further considerations beyond water purification

The effectiveness of pure drinking water, sanitation and hygiene by the Campbell/Cochrane collaboration showed 66 rigorous evaluations and 71 interventions (accounting for 30,000 children in 35 countries). Point of use water quality was associated with positive outcomes and so did hand-washing with soap. The Cochrane data base of systemic reviews discussed the effect of hand washing promotion for preventing diarrhea induced nutritional deficiency 9 , retarded child development 10 and deaths in low- and middle-income countries. The list of interventions to improve water quality by eliminating or reducing pathogens with the objective of preventing diarrhea is substantial.

Our results on markedly reduced incidence of diarrhea after implementation of the hemodialyzer filtration device agree with prior studies. In Clasen’s data synthesis paper 11 on 42 studies in 21 countries showed that all interventions to improve the microbial quality of drinking water were effective in reducing diarrheal incidents even though variations in design and application of water cleansing systems limit comparability of their cited studies. Results are less consistent for the role of other common environmental interventions (such as sanitation, or instruction in hygiene) 12 .

Our study using monthly surveys of diarrhea in households may be considered soft data, however the magnitude of a relative 72% reduction in the incidence of diarrhea per monitored population is strikingly large. It is also corroborated by many mothers reporting spontaneously a sudden virtual absence of diarrhea in their children after availability of the dialyzer-filtered water. The marked reduction in the diarrhea incidence is likely due to using sterile water instead of using river water polluted with known pathogens, such as E. coli , as the main source of drinking water. It may be expected that combination of installing a membrane filtration device and combining it with WASH initiatives will have a strong amplified effect as compared to clean water provision alone. This however remains to be shown in further prospective research.

The hemodialyzer membrane filtration device used in this study was clearly associated with a substantial reduction in the incidence of self-reported diarrhea compared to the prior period and compared to a control group without the device. Use of repurposed hemodialyzers, that had already saved lives once in their initial purpose in renal replacement therapy, can again serve as an affordable means of water purification to again save lives within entire communities. Our hemodialyzer membrane filtration approach using hollow fibers with pore size as tight as 0.003 µm in the a surface-maximizing configuration used in the technology of the device described in this paper is highly effective and unique. This renders it not only eligible but potentially highly effective to allow the world population to successfully accomplish the United Nations’ Sustainable Development Goal 6.

Kuberan, A. et al. Water and sanitation hygiene knowledge, attitude, and practices among household members living in rural setting of India. J. Nat. Sci. Biol. Med. 6 , S69-74. https://doi.org/10.4103/0976-9668.166090 (2015).

Article   PubMed   PubMed Central   Google Scholar  

Peter-Varbanets, M., Zurbrugg, C., Swartz, C. & Pronk, W. Decentralized systems for potable water and the potential of membrane technology. Water Res. 43 , 245–265. https://doi.org/10.1016/j.watres.2008.10.030 (2009).

Article   CAS   PubMed   Google Scholar  

Cerda, J. et al. Epidemiology of acute kidney injury. Clin. J. Am. Soc. Nephrol. 3 , 881–886. https://doi.org/10.2215/CJN.04961107 (2008).

Article   PubMed   Google Scholar  

Mehta, R. L. et al. Recognition and management of acute kidney injury in the International Society of Nephrology 0by25 Global Snapshot: a multinational cross-sectional study. Lancet 387 , 2017–2025. https://doi.org/10.1016/S0140-6736(16)30240-9 (2016).

Collaborators, G. B. D. L. R. I. Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory infections in 195 countries, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet. Infect. Dis. 18 , 1191–1210. https://doi.org/10.1016/S1473-3099(18)30310-4 (2018).

Article   Google Scholar  

Piper, J. D. et al. Water, sanitation and hygiene (WASH) interventions: effects on child development in low- and middle-income countries. Cochrane Database Syst. Rev. https://doi.org/10.1002/14651858.CD012613 (2017).

McAllister, D. A. et al. Global, regional, and national estimates of pneumonia morbidity and mortality in children younger than 5 years between 2000 and 2015: a systematic analysis. Lancet Glob. Health 7 , e47–e57. https://doi.org/10.1016/S2214-109X(18)30408-X (2019).

Patrier, L. et al. FGF-23 removal is improved by on-line high-efficiency hemodiafiltration compared to conventional high flux hemodialysis. J. Nephrol. 26 , 342–349. https://doi.org/10.5301/jn.5000150 (2013).

Abdoli, A. & Maspi, N. Commentary: estimates of global, regional, and national morbidity, mortality, and aetiologies of diarrhoeal diseases: a systematic analysis for the global burden of disease study 2015. Front. Med. 5 , 11. https://doi.org/10.3389/fmed.2018.00011 (2018).

Collaborators, G. L. Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. Infect. Dis. 17 , 1133–1161. https://doi.org/10.1016/S1473-3099(17)30396-1 (2017).

Canaud, B., Koehler, K., Bowry, S. & Stuard, S. What is the optimal target convective volume in on-line hemodiafiltration therapy?. Contrib. Nephrol. 189 , 9–16. https://doi.org/10.1159/000450634 (2017).

Bowry, S. K. & Canaud, B. Achieving high convective volumes in on-line hemodiafiltration. Blood Purif. 35 (Suppl 1), 23–28. https://doi.org/10.1159/000346379 (2013).

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Acknowledgments

First and foremost, we would like to thank those who have made this study possible by their generous donations. We further would like to thank all those that supported our work and helped us to get to the point we currently are. Last but certainly not least we would like to thank the village committees and everybody in the studied villages (Adzakeh, Agamakope, Alewusedekope, Amekutsekope, Anazome, Azizakope, Baitlenya and Tornyikope).

Author information

Authors and affiliations.

Easy Water for Everyone, 10 Bank Street, Suite 560, White Plains, NY, 10606, USA

Jochen G. Raimann, Seth Johnson, Linda Donald, Friedrich Port & Nathan W. Levin

Research Division, Renal Research Institute, New York, USA

• Jochen G. Raimann

Katz School at Yeshiva University, New York, USA

Easy Water for Everyone, Accra, Ghana

Jochen G. Raimann, Joseph Marfo Boaheng, Philipp Narh, Harrison Matti, Seth Johnson, Linda Donald & Nathan W. Levin

Department of Field Epidemiology and Applied Biostatistics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

• Joseph Marfo Boaheng

Ghana Health Services, Big Ada, Ghana

Philipp Narh

Department of Epidemiology and Biostatistics, CUNY Graduate School of Public Health and Health Policy, City University of New York, New York, USA

Hongbin Zhang

CUNY Institute for Implementation Science in Population Health, New York, USA

Departments of Medicine (Nephrology) and Epidemiology, University of Michigan, Ann Arbor, MI, USA

Friedrich Port

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Conceptualization: J. R., S. J., L. D. and N. L.; Data curation: J. R., J. M. B., P. N. and F. P.; Formal analysis: J. R., J. M. B., H. Z. and F. P.; Funding acquisition: L. D. and N. L.; Investigation: J. R., J. M. B., H. Z., F. P. and N. L.; Methodology: J. R., J. M. B., H. Z., F. P. and N. L.; Project administration: P. N., L. D. and N. L.; Resources: J. R., P. N., S. J., H. Z. and N. L.; Software: J. R. and J. M. B.; Supervision: N. L.; Validation: J. R., H. Z., F. P. and N. L.; Visualization: J. R., J. M. B. and F. P.; Writing—original draft: J. R., F. P. and N. L.; Writing—review & editing, J. R., J. M. B., P. N., S. J., L. D., H. Z., F. P. and N. L.

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Jochen Raimann and Seth Johnson are employees of Renal Research Institute/Fresenius Medical Care. All other authors have no financial disclosure.

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Raimann, J.G., Boaheng, J.M., Narh, P. et al. Public health benefits of water purification using recycled hemodialyzers in developing countries. Sci Rep 10 , 11101 (2020). https://doi.org/10.1038/s41598-020-68408-1

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DOI : https://doi.org/10.1038/s41598-020-68408-1

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Surface modified Nanoparticles for Water Pollution Detection

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Water pollution is one of major concerns in the World. Directly or indirectly, it affects everyone in our planet. Surface-modified nanoparticles have emerged as promising tools for detecting water pollutants such as antibiotics, metal ions (lead, mercury, arsenic), endocrine disruptors, pesticides, and organic contaminants. These nanoparticles can be functionalized with various coatings including natural products, polymers, to enhance their specificity and sensitivity. Their large surface area-to-volume ratio facilitates interactions with contaminants at trace levels, enabling detection through mechanisms like fluorescence quenching, colorimetric changes, or electrochemical responses. Researchers are developing portable sensing platforms utilizing these properties for rapid, onsite water quality assessment. This research offers significant potential for addressing environmental challenges by providing sensitive, selective, and cost-effective solutions for monitoring water pollution. The goal of this Research Topic is to introduce advanced, low-cost, surface-modified nanoparticles for the effective detection of water pollutants such as antibiotics, metal ions, endocrine disruptors, and pesticides. Traditional methods for detecting these contaminants are often time-consuming, expensive, and require sophisticated laboratory equipment. By leveraging recent advances in nanotechnology, we aim to create a platform of scientific articles which describe highly sensitive, selective, and portable sensing platforms for detection as well as separation of water pollutants. Various nanoparticles including silica, gold, magnetic, polymeric etc., with their tailored surface modifications, can provide rapid, robust, on-site detection capabilities. Achieving this goal involves optimizing nanoparticle synthesis, enhancing surface functionalization techniques, and integrating these nanoparticles into user-friendly sensor devices. This approach promises to significantly improve water quality monitoring, ensuring timely and accurate detection of pollutants, and contributing to better environmental and public health outcomes. This Research Topic focuses on detection and purification of water pollutants using surface modified nanoparticles. We look for Original Research articles, Reviews, Mini-reviews or Perspective articles which advances low-cost alternative materials to overcome the hurdle in handling water pollution comprising the following topics: • Natural product conjugated nanoparticles for water pollutant detection and separation • Molecularly imprinted polymers for water pollution • Conjugation methods onto nanoparticles • Industrial application of nanoparticles to detect and separate water pollutants • Low-cost nanomaterials for water pollution • Polymer coated nanoparticles for water pollution • Nanomaterials synthesis, characterization and application in water pollution • Industrially available nanoparticles for water pollution: challenges and scope

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EPA to fund studies evaluating antimicrobial resistance in wastewater treatment

The US Environmental Protection Agency (EPA) yesterday announced $9 million in research grants to measure the environmental and health impact of antimicrobial resistance (AMR) in wastewater.

Oregon State University, the University of Nebraska, the University of Wisconsin-Milwaukee, and the Water Research Foundation in Denver will each receive more than $2 million to study wastewater and sewage sludge treatment systems across the county to better understand how they might aid the evolution and spread of AMR in the environment. 

More info needed on AMR in treated wastewater

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Since treated wastewater is discharged into rivers, streams, and other surface waters, that mixture of resistant pathogens and AMR genes may be transmitted to humans and animals. But the extent of transmission, and how it affects humans and animals, is still largely unknown.

"More information is needed to characterize the occurrence and significance of AMR found in treated municipal wastewater effluent and biosolids," the EPA said in a  news release . "In addition, new research is needed to provide a better understanding of the impact of AMR on receiving waters and risks related to AMR in treated wastewater discharge, water reuse, and biosolids."

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New research finds link between COVID-19 and gestational diabetes

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The investigators analyzed records from nearly 58,000 COVID diagnosis claims in pregnant women from 1 to 21 weeks gestation from March 2020 to October 2022. They compared them with records of more than 115,000 pregnant women who weren't diagnosed with COVID during the same period.

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The study authors wrote, "This is the first published study to assess the effectiveness of rVSV-ZEBOV outside a clinical trial and amid the most widespread use of the vaccine to date, during the second-largest Ebola virus disease outbreak ever recorded, addressing uncertainties in the real-world effectiveness of the vaccine left open by previous studies."

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The authors conclude, "Our findings reinforce the evidence for vaccinating individuals at risk of exposure to Ebola virus as early as possible during epidemics. Even in challenging settings, such as the eastern Democratic Republic of the Congo, rVSV-ZEBOV vaccination is a highly effective tool."

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Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS)

Bill b. wang.

Redlands East Valley High School, Redlands, California, United States of America

Associated Data

All relevant data are within the manuscript and its Supporting Information files.

This study, based in San Bernardino County, Southern California, collected and examined tap water samples within the area to explore the feasibility of adopting non-industrial equipment and methods to reduce water hardness and total dissolved solids(TDS). We investigated how water quality could be improved by utilizing water boiling, activated carbon and sodium bicarbonate additives, as well as electrolysis methods. The results show that heating is effective at lower temperatures rather than long boils, as none of the boiling tests were lower than the original value. Activated carbon is unable to lower TDS, because it is unable to bind to any impurities present in the water. This resulted in an overall TDS increase of 3.5%. However, adding small amounts of sodium bicarbonate(NaHCO 3 ) will further eliminate water hardness by reacting with magnesium ions and improve taste, while increasing the pH. When added to room temperature tap water, there is a continuous increase in TDS of 24.8% at the 30 mg/L mark. The new findings presented in this study showed that electrolysis was the most successful method in eliminating TDS, showing an inverse proportion where an increasing electrical current and duration of electrical lowers more amounts of solids. This method created a maximum decrease in TDS by a maximum of 22.7%, with 3 tests resulting in 15.3–16.6% decreases. Furthermore, when water is heated to a temperature around 50°C (122°F), a decrease in TDS of around 16% was also shown. The reduction of these solids will help lower water hardness and improve the taste of tap water. These results will help direct residents to drink more tap water rather than bottled water with similar taste and health benefits for a cheaper price as well as a reduction on plastic usage.

Introduction

The concentration of total dissolved solids(TDS) present in water is one of the most significant factors in giving water taste and also provides important ions such as calcium, magnesium, potassium, and sodium [ 1 – 3 ]. However, water with high TDS measurements usually indicates contamination by human activities, such as soil and agricultural runoff caused by irrigation, unregulated animal grazing and wildlife impacts, environmentally damaging farming methods such as slash and burn agriculture, and the overuse of nitrate-based fertilizer [ 4 , 5 ], etc. Around tourist areas as well as state parks, these factors will slowly add up over time and influence the water sources nearby [ 5 ]. Water that flows through natural springs and waterways with high concentrations of organic salts within minerals and rocks, or groundwater that originates from wells with high salt concentration will also result in higher particle measurements [ 6 ].

Water sources can be contaminated by substances and ions such as nitrate, lead, arsenic, and copper [ 7 , 8 ] and may cause many health problems related to heavy metal consumption and poisoning. Water reservoirs and treatments plants that do not consider water contamination by motor vehicles, as well as locations that struggle to provide the necessary components required for water treatment will be more prone to indirect contamination [ 9 – 11 ]. Many plants are effective in ensuring the quality and reduction of these contaminants, but often leave out the secondary considerations, The United States Environmental Protection Agency(US EPA)’s secondary regulations recommend that TDS should be below 500 mg/L [ 2 ], which is also supported by the World Health Organization(WHO) recommendation of below 600 mg/L and an absolute maximum of less than 1,000 mg/L [ 3 ]. These substances also form calcium or magnesium scales within water boilers, heaters, and pipes, causing excess buildup and drain problems, and nitrate ions may pose a risk to human health by risking the formation of N -nitroso compounds(NOC) and less public knowledge about such substances [ 12 – 15 ]. Nitrates can pose a non-carcinogenic threat to different communities, but continue to slip past water treatment standards [ 15 ]. Furthermore, most people do not tolerate or prefer water with high hardness or chlorine additives [ 16 ], as the taste changes tremendously and becomes unpreferable. Even so, TDS levels are not accounted for in mandatory water regulations, because the essential removal of harmful toxins and heavy metals is what matters the most in water safety. Some companies indicate risks in certain ions and alkali metals, showing how water hardness is mostly disregarded and is not as well treated as commercial water bottling companies [ 17 , 18 ].

In Southern California, water quality is not as well maintained than the northern counties as most treatment plants in violation of a regulation or standard are located in Central-Southern California [ 19 ], with southern counties having the largest number of people affected [ 20 ]. This study is focused on the Redlands area, which has had no state code violations within the last decade [ 21 ]. A previous study has analyzed TDS concentrations throughout the Santa Ana Basin, and found concentrations ranging from 190–600 ppm as treated wastewater and samples obtained from mountain sites, taking into account the urban runoff and untreated groundwater as reasons for elevated levels of TDS but providing no solution in helping reduce TDS [ 22 ]. Also, samples have not been taken directly through home water supplies, where the consumer is most affected. Other water quality studies in this region have been focused on the elimination of perchlorates in soil and groundwater and distribution of nitrates, but such research on chemicals have ceased for the last decade, demonstrated by safe levels of perchlorates and nitrates in water reports [ 23 , 24 ]. In addition to these studies, despite the improving quality of the local water treatment process, people prefer bottled water instead of tap water because of the taste and hardness of tap water [ 25 ]. Although water quality tests are taken and documented regularly, the taste of the water is not a factor to be accounted for in city water supplies, and neither is the residue left behind after boiling water. The residue can build up over time and cause appliance damage or clogs in drainage pipes.

This study will build upon previous analyses of TDS studies and attempt to raise new solutions to help develop a more efficient method in reducing local TDS levels, as well as compare current measurements to previous analyses to determine the magnitude to which local treatment plants have improved and regulated its treatment processes.

Several methods that lower TDS are reviewed: boiling and heating tap water with and without NaHCO₃, absorption by food-grade activated carbon [ 26 , 27 ], and battery-powered electrolysis [ 28 – 30 ]. By obtaining water samples and determining the difference in TDS before and after the listed experiments, we can determine the effectiveness of lowering TDS. The results of this study will provide options for residents and water treatment plants to find ways to maintain the general taste of the tap water, but also preserve the lifespan of accessories and pipelines. By determining a better way to lower TDS and treat water hardness, water standards can be updated to include TDS levels as a mandatory measurement.

Materials and methods

All experiments utilized tap water sourced from Redlands homes. This water is partially supplied from the Mill Creek (Henry Tate) and Santa Ana (Hinckley) Water Sheds/Treatment Plants, as well as local groundwater pumps. Water sampling and sourcing were done at relatively stable temperatures of 26.9°C (80.42°F) through tap water supplies. The average TDS was measured at 159 ppm, which is slightly lower than the reported 175 ppm by the City of Redlands. Permission is obtained by the author from the San Bernardino Municipal Water Department website to permit the testing procedures and the usage of private water treatment devices for the purpose of lowering water hardness and improving taste and odor. The turbidity was reported as 0.03 Nephelometric Turbidity Units (NTU) post-treatment. Residual nitrate measured at 2.3mg/L in groundwater before treatment and 0.2 mg/L after treatment and perchlorate measured at 0.9 μg/L before treatment, barely staying below the standard of 1 μg/L; it was not detected within post-treatment water. Lead content was not detected at all, while copper was detected at 0.15 mg/L.

For each test, all procedures were done indoors under controlled temperatures, and 20 L of fresh water was retrieved before each test. Water samples were taken before each experimental set and measured for TDS and temperature, and all equipment were cleaned thoroughly with purified water before and after each measurement. TDS consists of inorganic salts and organic material present in solution, and consists mostly of calcium, magnesium, sodium, potassium, carbonate, chloride, nitrate, and sulfate ions. These ions can be drawn out by leaving the water to settle, or binding to added ions and purified by directly separating the water and ions. Equipment include a 50 L container, 1 L beakers for water, a graduated cylinder, a stir rod, a measuring spoon, tweezers, a scale, purified water, and a TDS meter. A standard TDS meter is used, operated by measuring the conductivity of the total amount of ionized solids in the water, and is also cleaned in the same manner as aforementioned equipment. The instrument is also calibrated by 3 pH solutions prior to testing.All results were recorded for and then compiled for graphing and analysis.

Heating/Boiling water for various lengths of time

The heating method was selected because heat is able to break down calcium bicarbonate into calcium carbonate ions that are able to settle to the bottom of the sample. Four flasks of 1 L of tap water were each heated to 40°C, 50°C, 60°C, and 80°C (104–176°F) and observed using a laser thermometer. The heated water was then left to cool and measurements were made using a TDS meter at the 5, 10, 20, 30, and 60-minute marks.

For the boiling experiments, five flasks of 1 L of tap water were heated to boil at 100°C (212°F). Each flask, which was labeled corresponding to its boiling duration, was marked with 2, 4, 6, 10, and 20 minutes. Each flask was boiled for its designated time, left to cool under open air, and measurements were made using a TDS meter at the 5, 10, 20, 30, 60, and 120-minute marks. The reason that the boiling experiment was extended to 120 minutes was to allow the water to cool down to room temperature.

Activated carbon as a water purification additive

This test was performed to see if food-grade, powdered activated carbon had any possibility of binding with and settling out residual particles. Activated carbon was measured using a milligram scale and separated into batches of 1, 2, 4, 5, 10, 30, and 50 mg. Each batch of the activated carbon were added to a separate flask of water and stirred for five minutes, and finally left to settle for another five minutes. TDS measurements were recorded after the water settled.

Baking soda as a water purification additive

To lower scale error and increase experimental accuracy, a concentration of 200 mg/L NaHCO₃ solution was made with purified water and pure NaHCO₃. For each part, an initial TDS measurement was taken before each experiment.

In separate flasks of 1 L tap water, each labeled 1, 2, 4, 5, 10, and 30 mg of NaHCO 3 , a batch was added to each flask appropriately and stirred for 5 minutes to ensure that everything dissolved. Measurements were taken after the water was left to settle for another 5 minutes for any TDS to settle.

Next, 6 flasks of 1 L tap water were labeled, with 5 mg (25 mL solution) of NaHCO₃ added to three flasks and 10 mg (50 mL solution) of NaHCO₃ added to the remaining three. One flask from each concentration of NaHCO₃ was boiled for 2 mins., 4 mins., or 6 mins., and then left to cool. A TDS measurement was taken at the 5, 10, 20, 30, 60, and 120-minute marks after removal from heat.

Electrolysis under low voltages

This test was performed because the ionization of the TDS could be manipulated with electricity to isolate an area of water with lower TDS. For this test, two 10cm long graphite pieces were connected via copper wiring to a group of batteries, with each end of the graphite pieces submerged in a beaker of tap water, ~3 cm apart.

Using groups of 1.5 V double-A batteries, 4 beakers with 40mL of tap water were each treated with either 7.5, 9.0, 10.5, and 12.0 V of current. Electrolysis was observed to be present by the bubbling of the water each test, and measurements were taken at the 3, 5, 7, and 10 minute marks.

Results/Discussion

Heating water to various temperatures until the boiling point.

The goal for this test was to use heat to reduce the amount of dissolved oxygen and carbon dioxide within the water, as shown by this chemical equation: Heat: Ca(HCO 3 ) 2 → CaCO 3 ↓ + H 2 O + CO 2 ↑.

This would decompose ions of calcium bicarbonate down into calcium carbonate and water and carbon dioxide byproducts.

Patterns and trends in decreasing temperatures

The following trend lines are based on a dataset of changes in temperature obtained from the test results and graphed as Fig 1 .

To predict the precise temperature measurements of the tap water at 26.9°C, calculations were made based on Fig 1 . The fitting equations are in the format, y = a.e bx . The values for the fitting coefficients a and b, and correlation coefficient R 2 are listed in Table 1 as column a, b and R 2 . The calculated values and the target temperature are listed in Table 1 .

Fig 2 was obtained by compiling TDS results with different temperatures and times.

The fitting equations for Fig 2 are also in the format, y = a.e bx . The fitting coefficients a and b, and correlation coefficient R 2 values are listed in Table 2 . Based on the fitting curves in Fig 2 and the duration to the target temperature in Table 1 , We calculated the TDS at 26.9°C as listed in column calculated TDS in Table 2 based on the values we reported on Fig 2 .

Based on the heating temperature and the calculated TDS with the same target water temperature, we obtained the following heating temperature vs TDS removal trend line and its corresponding fitting curve in Table 2 .

In Fig 1 , a trend in the rate of cooling is seen, where a higher heating temperature creates a steeper curve. During the first five minutes of cooling, the water cools quicker as the absorbed heat is quickly released into the surrounding environment. By the 10-minute mark, the water begins to cool in a linear rate of change. One detail to note is that the 100°C water cools quicker than the 80°C and eventually cools even faster than the 60°C graph. Table 1 supports this observation as the duration to target temperature begins to decrease from a maximum point of 94.8 mins to 80.95 mins after the 80°C mark.

As shown in Fig 2 , all TDS values decrease as the temperature starts to cool to room temperature, demonstrating a proportional relationship where a lower temperature shows lower TDS. This can partially be explained by the ions settling in the flasks. Visible particles can also be observed during experimentation as small white masses on the bottom, as well as a thin ring that forms where the edge of the water contacts the flask. When the water is heated to 40°C and cooled, a 3.8% decrease in TDS is observed. When 50°C is reached, the TDS drops at its fastest rate from an initial value of 202 ppm to 160 ppm after 60 minutes of settling and cooling. The TDS measurements in these experiements reach a maximum of 204 ppm at the 60°C mark. However, an interesting phenomenon to point out is that the water does not hit a new maximum at 100°C. meaning that TDS reaches a plateau at 60°C. Also, the rate of decrease begins to slow down after 20 minutes, showing that an unknown factor is affecting the rate of decrease. It is also hypothesized that the slight increase in TDS between the 5–20 minute range is caused by a disturbance in the settling of the water, where the temperature starts to decrease at a more gradual and constant rate. The unstable and easy formation of CaCO 3 scaling has also been the subject of a study of antiscaling methods, which also supports the result that temperature is a significant influence for scale formation [ 12 ].

In Table 2 , calculations for TDS and the time it takes for each test to cool were made. Using the data, it is determined that the test with 50°C water decreased the most by 16% from the initial measurement of 159ppm. This means that it is most effective when water is heated between temperatures of 40–60°C when it comes to lowering TDS, with a difference of ~7–16%. When water is heated to temperatures greater than 80°C, the water begins to evaporate, increasing the concentration of the ions, causing the TDS to increase substantially when cooled to room temperature.

Finally, in Fig 3 , a line of best fit of function f(x) = -0.0007x 3 + 0.1641x 2 –10.962x + 369.36 is used with R 2 = 0.9341. Using this function, the local minimum of the graph would be reached at 48.4°C.

This data shows that heating water at low temperatures (i.e. 40–50°C) may be more beneficial than heating water to higher temperatures. This study segment has not been presented in any section within the United States EPA Report on water management for different residual particles/substances. However, warmer water temperatures are more prone to microorganism growth and algal blooms, requiring more intensive treatment in other areas such as chlorine, ozone, and ultraviolet disinfection.

Using the specific heat capacity equation, we can also determine the amount of energy and voltage needed to heat 1 L of water up to 50°C: Q = mcΔT, where c, the specific heat capacity of water, is 4.186 J/g°C, ΔT, the change in temperature from the experimental maximum to room temperature, is 30°C, and m, the mass of the water, is 1000 g. This means that the amount of energy required will be 125580 J, which is 0.035 kWh or 2.1 kW.

After taking all of the different measurements obtained during TDS testing, and compiling the data onto this plot, Fig 4 is created with a corresponding line of best fit:

In Fig 4 , it can be observed that the relationship between the temperature of the water and its relative TDS value is a downwards facing parabolic graph. As the temperature increases, the TDS begins to decrease after the steep incline at 50–60°C. The line of best fit is represented by the function f(x) = -0.0142x 2 + 2.258x + 105.84. R 2 = 0.6781. Because the R 2 value is less than expected, factors such as the time spent settling and the reaction rate of the ions should be considered. To determine the specifics within this experiment, deeper research and prolonged studies with more highly accurate analyses must be utilized to solve this problem.

Boiling water for various amounts of time

Trend of boiling duration and rate of cooling.

Using the same methods to create the figures and tables for the previous section, Fig 5 depicts how the duration of time spent boiling water affects how fast the water cools.

As seen in Fig 5 , within the first 10 minutes of the cooling time, the five different graphs are entwined with each other, with all lines following a similar pattern. However, the graph showing 20 minutes of boiling is much steeper than the other graphs, showing a faster rate of cooling. This data continues to support a previous claim in Fig 2 , as this is most likely represented by a relationship a longer the boil creates a faster cooling curve. This also shows that the first 5 minutes of cooling have the largest deviance compared to any other time frame.

The cooling pattern is hypothesized by possible changes in the orderly structure of the hydrogen bonds in the water molecules, or the decreased heat capacity of water due to the increasing concentration of TDS.

Effect on TDS as boiling duration increases

In Fig 6 , all lines except for the 20-minute line are clustered in the bottom area of the graph. By excluding the last measurement temporarily due to it being an outlier, we have observed that the difference between the initial and final TDS value of each test decreases.

Despite following a similar trend of an increase in TDS at the start of the tests and a slow decrease overtime, this experiment had an interesting result, with the final test measuring nearly twice the amount of particles compared to any previous tests at 310 ppm, as shown in Fig 6 . It is confirmed that the long boiling time caused a significant amount of water to evaporate, causing the minerals to be more concentrated, thus resulting in a 300 ppm reading. Fig 6 follows the same trend as Fig 2 , except the TDS reading veers away when the boiling duration reaches 20 minutes. Also, with the long duration of heating, the water has developed an unfavorable taste from intense concentrations of CaCO₃. This also causes a buildup of a thin crust of CaCO₃ and other impurities around the container that is difficult to remove entirely. This finding is in accordance with the introductory statement of hot boiling water causing mineral buildups within pipes and appliances [ 9 ]. A TDS reading of 300ppm is still well below federal secondary standards of TDS, and can still even be compared to bottled water, in which companies may fluctuate and contain 335ppm within their water [ 1 , 2 ].

This experiment continues to stupport that the cooling rate of the water increases as the time spent boiling increases. Based on this test, a prediction can be made in which an increased concentration of dissolved solids lowers the total specific heat capacity of the sample, as the total volume of water decreases. This means that a method can be derived to measure TDS using the heat capacity of a tap water mixture and volume, in addition to current methods of using the electrical conductivity of aqueous ions.

Adding food-grade activated carbon to untreated tap water

Fig 7 presents a line graph with little to no change in TDS, with an initial spike from 157 to 163 ppm. The insoluble carbon remains in the water and shows no benefit.

The food-grade activated carbon proved no benefit to removing TDS from tap water, and instead added around 5–7 ppm extra, which settled down to around +4 ppm at 120 minutes. The carbon, which is not 100% pure from inorganic compounds and materials present in the carbon, can dissolve into the water, adding to the existing concentration of TDS. Furthermore, household tap water has already been treated in processing facilities using a variety of filters, including carbon, so household charcoal filters are not effective in further reducing dissolved solids [ 18 ].

Adding sodium bicarbonate solution to boiled tap water

As seen in Fig 8 , after adding 1 mg of NaHCO 3 in, the TDS rises to 161 ppm, showing a minuscule increase. When 4 mg was added, the TDS drops down to 158 ppm. Then, when 5 mg was added, a sudden spike to 172 ppm was observed. This means that NaHCO 3 is able to ionize some Ca 2+ and Mg 2+ ions, but also adds Na + back into the water. This also means that adding NaHCO 3 has little to no effect on TDS, with 4mg being the upper limit of effectiveness.

To examine whether or not the temperature plays a role in the effectiveness in adding NaHCO 3 , a boiling experiment was performed, and the data is graphed in Fig 9 .

Fig 9 presents the relationship between the amount of common baking soda(NaHCO₃) added, the boiling time involved, and the resulting TDS measurements. After boiling each flask for designated amounts of time, the results showed a downward trend line from a spike but does not reach a TDS value significantly lower than the initial sample. It is apparent that the NaHCO₃ has not lowered the TDS of the boiling water, but instead adds smaller quantities of ions, raising the final value. This additive does not contribute to the lowering of the hardness of the tap water. However, tests boiled with 5 mg/L of baking soda maintained a downward pattern as the water was boiled for an increasing amount of time, compared to the seemingly random graphs of boiling with 10 mg/L.

In some households, however, people often add NaHCO₃ to increase the pH for taste and health benefits. However, as shown in the test results, it is not an effective way of reducing TDS levels in the water [ 10 , 16 ], but instead raises the pH, determined by the concentration added. Even under boiling conditions, the water continues to follow the trend of high growth in TDS, of +25–43 ppm right after boiling and the slow drop in TDS (but maintaining a high concentration) as the particles settle to the bottom.

Utilizing the experimental results, we can summarize that after adding small batches of NaHCO3 and waiting up to 5 minutes will reduce water hardness making it less prone to crystallizing within household appliances such as water brewers. Also, this process raises the pH, which is used more within commercial water companies. However, the cost comes at increasing TDS.

Using electrolysis to treat TDS in tap water

Different voltages were passed through the water to observe the change in TDS overtime, with the data being compiled as Fig 10 .

The process of electrolysis in this experiment was not to and directly remove the existing TDS, but to separate the water sample into three different areas: the anode, cathode, and an area of clean water between the two nodes [ 19 ]. The anions in the water such as OH - , SO 4 2- , HCO 3 - move to the anode, while the cations such as H + , Ca 2+ 、Mg 2+ 、Na + move to the cathode. The middle area would then be left as an area that is more deprived of such ions, with Fig 10 proving this.

As shown in Fig 10 , electrolysis is effective in lower the TDS within tap water. Despite the lines being extremely tangled and unpredictable, the general trend was a larger decrease with a longer duration of time. At 10 minutes, all lines except 10.5 V are approaching the same value, meaning that the deviation was most likely caused by disturbances to the water during measurement from the low volume of water. With each different voltage test, a decrease of 12.7% for 6.0 V, 14.9% for 9.0 V, 22.7% for 10.5 V. and 19.5% for 12.0 V respectfully were observed. In the treatment of wastewate leachate, a study has shown that with 90 minutes of electrical treatment, 34.58% of TDS content were removed, supporting the effectiveness of electricity and its usage in wastewater treatment [ 29 ].

This experiment concludes that electrolysis is effective in lowering TDS, with the possibility to improve this process by further experimentation, development of a water cleaning system utilizing this cathode-anode setup to process water. This system would be a more specific and limited version of a reverse osmosis system by taking away ions through attraction, rather than a filter.

The Southern Californian tap water supply maintains TDS values below the federal regulations. However, crystalline scale buildup in household appliances is a major issue as it is hard to clean and eliminate. To easily improve the taste and quality of tap water at home as well as eliminating the formation of scales, the following methods were demonstrated as viable:

• By heating water to around 50°C (122°F), TDS and water hardness will decrease the most. Also, the boiling process is effective in killing microorganisms and removing contaminants. This process cannot surpass 10 minutes, as the concentration of the ions in the water is too high, which poses human health risks if consumed. These, along with activated carbon and NaHCO₃ additives, are inefficient methods that have minimal effects for lowering TDS.
• Electrolysis is one of the most effective methods of eliminating TDS. Experiments have proven that increased current and duration of time helps lower TDS. However, this method has yet to be implemented into conventional commercial water filtration systems.

Also, some observations made in these experiments could not be explained, and require further research and experimentation to resolve these problems. The first observation is that TDS and increasing water temperature maintain a parabolic relationship, with a maximum being reached at 80°C, followed by a gradual decrease. The second observation is that when water is boiled for an increased duration of time, the rate of cooling also increases.

This experiment utilized non-professional scientific equipment which are prone to mistakes and less precise. These results may deviate from professionally derived data, and will require further study using more advanced equipment to support these findings.

Acknowledgments

The author thanks Tsinghua University Professor and PLOS ONE editor Dr. Huan Li for assisting in experimental setups as well as data processing and treatment. The author also thanks Redlands East Valley High School’s Dr. Melissa Cartagena for her experimental guidance, and Tsinghua University Professor Dr. Cheng Yang for proofreading the manuscript.

Funding Statement

The author received no specific funding for this work.

Data Availability

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August 23, 2024

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Scientists uncover new mechanism of 'forgetting' in brain neurons that could inform Parkinson's treatment

by Olivia Dimmer, Northwestern University

Northwestern Medicine investigators have uncovered a new way in which neurons in the brain "forget" associations that help guide behavior and habits, according to a study published in Cell Reports .

In addition to shedding light on basic brain mechanisms, the findings could also prove useful in treating Parkinson's disease, said D. James Surmeier, Ph.D., the Nathan Smith Davis Professor and chair of Neuroscience, who was senior author of the study.

In the study, Surmeier and a team of Northwestern Medicine scientists set out to understand how spiny projection neurons —the principal neurons in the striatum, a key part of the brain circuitry controlling decision making—are affected by neuronal plasticity, which is critical to the brain's ability to change and adapt over time in response to life experiences.

"Some years ago, we discovered a novel form of long-term synaptic depression in spiny projection neurons that was triggered by a gaseous messenger called nitric oxide," Surmeier said. "The stratum is one of the few places in the brain that has very high levels of the signaling molecules that respond to nitric oxide. We wanted to get a better understanding of the role that form of plasticity played in controlling behavior."

First, investigators studied an early step in the biochemical cascade triggered by nitric oxide—the metabolism of cyclic guanosine monophosphate (cGMP). They found that cGMP in spiny projection neurons was degraded by an enzyme (PDE1) that was turned on when neurons were active and letting calcium come into them.

They went on to find that the calcium activating PDE1 was coming through a specific type of membrane channel (Ca v 1.3 channel). This meant that the long-term depression of synapses triggered by nitric oxide was blocked in parts of the neuron that were actively processing information, in contrast to parts that were inactive.

This finding reveals how striatal spiny projection neurons operate on a "use it or lose it" basis, weakening synapses that were not actively involved in controlling behavior, Surmeier said.

"All of the commonly described forms of synaptic plasticity are dependent upon activity," Surmeier said. "No one to our knowledge has described a form of synaptic plasticity that was enabled by inactivity at specific locations in a neuron."

Next, investigators sought to understand this type of synaptic depression in the context of Parkinson's disease.

In a mouse model of Parkinson's disease, investigators observed that nitric oxide signaling and the synaptic depression it controlled was significantly diminished. However, by rebalancing levels of two neurotransmitters that are disrupted in Parkinson's disease—dopamine and acetylcholine—investigators were able to restore nitric oxide signaling and this form of synaptic plasticity, according to the findings.

While more work is needed, the results suggest that nitric-oxide dependent synaptic depression could be a potential therapeutic target for Parkinson's, Surmeier said.

"We found that the generation of nitric oxide was dependent upon reestablishing a balance between dopaminergic and cholinergic signaling," Surmeier said. "Now, the question is how restoring nitric oxide signaling might fix what goes wrong in the striatum of Parkinson's disease patients."

Moving forward, Surmeier and his collaborators will continue to study the mechanisms of neuronal plasticity using cutting-edge techniques, he said.

"One of the things that we're particularly excited about is that the tools we have to monitor and manipulate brain circuits has rapidly expanded, deepening our understanding of how Parkinson's disease affects the brain and giving us strategies for reversing the changes in circuitry that cause symptoms," he said.

"We are also excited about new tools to manipulate nitric oxide signaling being developed by the Silverman lab here at NU."

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