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Water treatment

From Wikipedia
water treatment
industry
Subclass oftreatment, physical process Edit
Get useIrrigation Edit
Product or material producedDrinking water, water Edit
Dalecarlia Water Treatment Plant, Washington, D.C.

Water treatment be any process wey dey improve de quality of water make e fit for a particular use. Dat use fit be drinking, industrial water supply, irrigation, keeping river flow, water recreation, anaa plenty other purposes, wey dey include returning de water safely back into de environment. Water treatment dey remove contaminants den oda unwanted substances, anaa reduce de amount insyd de water, so de water go fit for de purpose wey dem want use am for. Dis treatment be very important for human health wey e help people use water safely for drinking den irrigation.

Insyd recent decades, scientists develop more advanced water treatment methods secof growing concerns about new pollutants like microplastics, pharmaceuticals, den per- and polyfluoroalkyl substances (PFAS). Dese methods dey include advanced oxidation processes, membrane filtration, den adsorption techniques wey dey use special materials like engineered nanomaterials den activated carbon. Besides dat, people dey pay more attention to energy efficiency, resource recovery, den sustainability for water treatment systems, especially for places wey water scarce den environmental challenges dey increase.[1]

Types

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Drinking water treatment

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Water contamination mostly happen secof industries den commercial businesses discharge untreated wastewater. Wastewater from different companies, wey get different kinds den amounts of contaminants, often enter rivers den oda water sources. De wastewater fit contain plenty organic den inorganic contaminants from de beginning. Industries produce wastewater thru manufacturing processes, paper den pulp production, textile production, chemical industries, den systems like cooling towers, boilers, den production lines.[2]

Typical drinking water treatment processes

Treatment for drinking water production dey involve removing contaminants den making harmful microorganisms inactive from raw water so de final water go pure enough for human consumption widout causing any short-term anaa long-term health problems. De biggest microbial risks usually come from drinking water contaminated plus human anaa animal (wey dey include bird) feces. Feces fit carry harmful bacteria, viruses, protozoa, den helminths. Removing anaa destroying dese disease-causing microorganisms be very important. Dis usually involve using chemical agents together plus treatment methods to remove suspended solids, bacteria, algae, viruses, fungi, den minerals like iron den manganese. Research, wey dey include de work of Professor Linda Lawton den ein team at Robert Gordon University, Aberdeen, dey help improve de detection of cyanobacteria.[3] Dese harmful substances still dey affect chaw developing countries wey no get effective water purification systems.

Making sure water quality dey good no depend only on treatment. E sanso include how de treated water be transported den distributed. Secof dis, e be common practice to leave a small amount of disinfectant inside treated water to kill bacteria during distribution den keep water pipes clean.[4]

Water wey people receive for house thru tap water anaa oda domestic uses fit receive extra treatment before use. Dese additional treatments fit include water softening anaa ion exchange.

At Turun Seudun Vesi Oy ein artificial groundwater plant, de pretreated raw water from de Kokemäki River dey soak thru de basins enter de Virttaankangas ridge formation.

Processes

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Empty aeration tank for iron precipitation

To remove hazardous chemicals from water, people dey use different treatment methods.[5]

De processes wey dey remove contaminants include physical methods like settling den filtration, chemical methods like disinfection den coagulation, den biological methods like slow sand filtration.

Water treatment plants around de world choose one anaa more of dese processes wey dey depend on de season den de type of contaminants den chemicals insyd de raw water.

Chemical

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Tanks plus sand filters to remove precipitated iron (no dey work at de time)

Different chemical treatment methods dey help convert harmful substances into safer forms anaa remove pollutants completely before safe disposal.[6]

  • Pre-chlorination to control algae growth den stop biological growth.
  • Aeration together plus pre-chlorination to remove dissolved iron wen small amounts of manganese dey present.
  • Disinfection to kill bacteria, viruses, den oda disease-causing microorganisms by using chlorine, ozone, anaa ultraviolet light.

Chemical

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Tanks wey get sand filters to remove iron wey don settle (dem no dey work for dat time)

Different chemical methods dey help convert substances into final products anaa remove pollutants so dem fit safely remove contaminants.[6]

  • Pre-chlorination to control algae den stop biological growth.
  • Aeration plus pre-chlorination to remove dissolved iron, especially if small amount of manganese dey inside.
  • Disinfection to kill bacteria, viruses den oda pathogens by using chlorine, ozone den ultraviolet light.

Physical

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Physical water den wastewater treatment methods dey depend on physical processes instead of biological anaa chemical changes to remove contaminants.[6]

De most common physical methods be:

  • Sedimentation be one of de main wastewater treatment processes. Gravity settling separate particles from liquid. As water speed reduce during treatment, suspended particles begin settle down secof gravity.[7][8] E dey mainly remove suspended solids wey trap insyd floc.
  • Filtration dey remove pollutants based on particle size. Removing pollutants from wastewater make am possible to reuse de water for different purposes. De type of filter wey dem go use depend on de contaminants insyd de water. Particle filtration den membrane filtration be de two main filtration methods.[9]
  • Dissolved air flotation (Degasification) be process wey dey remove dissolved gases from solution. According to Henry's law, de amount of gas wey dissolve insyd liquid depend on de gas pressure. Degasification be low-cost way to remove carbon dioxide gas from wastewater, wey dey increase de water pH by removing de gas.[6]
  • Deaerator dey reduce oxygen den nitrogen for boiler feed water applications.

Physico-chemical

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Dem sanso dey call am "Conventional" Treatment.

  • Coagulation for flocculation. Adding coagulants dey destabilize colloidal suspensions by neutralizing dema charges, wey make de smaller particles join together during coagulation.[10]
  • Coagulant aids, wey dem sanso dey call polyelectrolytes, dey improve coagulation den help create stronger flocs.
  • Polyelectrolytes anaa polymers normally get either positive anaa negative charge. De type wey dem go choose depend on de characteristics of de source water.
  • Most times dem dey use dese togeda plus primary coagulants like ferric chloride, ferric sulfate anaa alum.

Chemical precipitation be common process wey dey reduce heavy metals concentration for wastewater. Dissolved metal ions dey change into insoluble form thru chemical reaction plus precipitating agents like lime. For industrial work, dem fit use stronger alkalis to make de precipitation complete. For drinking water treatment, de common-ion effect dey help reduce water hardness.[11]

Flotation dey use bubbles attach to solids anaa dispersed liquids so dem fit separate dem from liquid phase.[12]

Membrane filtration

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Membrane filtration fit remove suspended solids, organic substances, plus inorganic pollutants like heavy metals. To remove heavy metals, dem fit use different types of membrane filtration like ultrafiltration, nanofiltration, den reverse osmosis, wey dey depend on de particle size wey de membrane fit hold back.[13][14] Antiscalants fit help maintain membrane filtration system.[15] Some very small molecules fit still permeate pass thru sam membranes.[15]

Ion exchange

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Ion exchange be reversible process wey one insoluble substance (resin) take ions from electrolytic solution den release oda ions wey get de same charge in almost equal amount, widout changing de structure of de resin.[16][17]

Electrochemical treatment techniques

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  • Electrodialysis (ED)
  • Membrane electrolysis (ME)
  • Electrochemical precipitation (EP)[14]

Adsorption

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Adsorption be mass transfer process wey one substance move from liquid phase go de surface of solid anaa liquid adsorbent, then e attach der physically anaa chemically as adsorbate. Dem dey divide adsorption into two types based on de attraction between de adsorbent den adsorbate: physical adsorption (physisorption) den chemical adsorption (chemisorption).[18][19]

Activated carbon
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Activated carbons (ACs) anaa biological-activated carbon (BAC)[20] be very effective adsorbents for many different contaminants. One of de industrial uses be removing colour, smell, taste den oda harmful organic den inorganic substances from drinking water den wastewater thru adsorption.[21]

If activated carbon get high surface area plus plenty pores, e dey work better. Plenty studies use activated carbon remove heavy metals den oda contaminants from wastewater. Buh commercial activated carbon (AC) don cam be expensive secof e no dey enough. Secof de high surface area, porosity den flexibility, activated carbon still get plenty potential for wastewater treatment.[21]

Biological

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Dis method be wer dem dey remove dissolved den suspended organic chemical substances thru biodegradation, wer dem add correct amount of microorganism so dem fit continue de same natural self-purification process wey dey happen for nature.[22]

Microorganisms fit break down organic matter for wastewater thru two main biological processes: biological oxidation den biosynthesis.

For biological oxidation, microorganisms dey convert organic materials insyd wastewater into end products like minerals, carbon dioxide, den ammonia. Dese products remain insyd de wastewater den later dey discharge plus de effluent.

For biosynthesis, microorganisms dey use organic materials insyd wastewater to create new microbial cells. Dis new biomass go cam be dense wey later dem remove am thru sedimentation.[23]

Standards

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Countries wer tap water dey safe to drink (blue)

Many developed countries get dema own standards wey dem dey apply locally. For Europe, dis include de European Drinking Water Directive[24], while for United States, de United States Environmental Protection Agency (EPA) set standards under de Safe Drinking Water Act.

For countries wey no get strong legal framework, de World Health Organization provide guidelines wey dem fit follow.[25]

China sanso get dema own drinking water standard GB3838-2002 (Type II) under de Ministry of Environmental Protection insyd 2002.[26]

Even where standards dey exist, most of them be guidelines or targets instead of strict laws, wey only few get real enforcement power.[27]

Only exceptions be de European Drinking Water Directive den de Safe Drinking Water Act for United States, wey require legal compliance.

Developing countries

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Appropriate technology for water treatment for developing countries include both community-scale systems den household-level point-of-use (POU) anaa self-supply systems.[28]

Some of dese systems dey use solar water disinfection (SODIS), wer sunlight, especially UV-A rays, dey kill harmful microorganisms for water directly anaa indirectly plus photocatalysts like titanium dioxide (TiO₂).[29]

Even though SODIS technology improve, military surplus water treatment units like ERDLator still be used for some developing areas. New portable Reverse Osmosis Water Purification Units (ROWPU) sanso cam be more available for civilian use.[30]

For waterborne disease control to last long, treatment programs wey research groups start for developing countries for be sustainable by local people, so dat wen external teams leave, de system go still continue working well.

Energy Consumption

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Water treatment plants fit consume plenty energy. For example, for California, more dan 4% of electricity consumption dey go into moving den treating water over long distances.[31]

For areas where clean water dey flow by gravity, energy cost dey low. But pumping water dey consume most of de energy insyd many systems.

Some low-energy water treatment methods include trickling filters, slow sand filters, den gravity aqueduct systems.

Materials

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Stainless steels like Type 304L den 316L widely be use for building water treatment plants secof dem resist corrosion from water den chlorine used for disinfection.[32][33]

References

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  1. ↑ Nishmitha, P. S.; Akhilghosh, Kochuparambil Ajayaghosh; Aiswriya, Vijayalekshmi Padmachandran; Ramesh, Athira; Muthuchamy, Muthukumar; Muthukumar, Anbazhagi (2025-05-01). "Understanding emerging contaminants in water and wastewater: A comprehensive review on detection, impacts, and solutions". Journal of Hazardous Materials Advances. 18 100755. doi:10.1016/j.hazadv.2025.100755. ISSN 2772-4166.
  2. ↑ Singh, N. B.; Nagpal, Garima; Agrawal, Sonal; Rachna (2018-08-01). "Water purification by using Adsorbents: A Review". Environmental Technology & Innovation (in English). 11: 187–240. Bibcode:2018EnvTI..11..187S. doi:10.1016/j.eti.2018.05.006. ISSN 2352-1864. S2CID 103693107.
  3. ↑ "Linda Lawton – 11th International Conference on Toxic Cyanobacteria" (in American English). Retrieved 2021-06-25.
  4. ↑ "Chlorine". Drinking water inspectorate. Retrieved 2 March 2023.
  5. ↑ Jothirani, R.; Kumar, P. Senthil; Saravanan, A.; Narayan, Abishek S.; Dutta, Abhishek (2016-07-25). "Ultrasonic modified corn pith for the sequestration of dye from aqueous solution". Journal of Industrial and Engineering Chemistry (in English). 39: 162–175. doi:10.1016/j.jiec.2016.05.024. ISSN 1226-086X.
  6. 1 2 3 4 Saravanan, A.; Senthil Kumar, P.; Jeevanantham, S.; Karishma, S.; Tajsabreen, B.; Yaashikaa, P. R.; Reshma, B. (2021-10-01). "Effective water/wastewater treatment methodologies for toxic pollutants removal: Processes and applications towards sustainable development". Chemosphere (in English). 280 130595. Bibcode:2021Chmsp.28030595S. doi:10.1016/j.chemosphere.2021.130595. ISSN 0045-6535. PMID 33940449.
  7. ↑ Gottfried, A.; Shepard, A. D.; Hardiman, K.; Walsh, M. E. (2008-11-01). "Impact of recycling filter backwash water on organic removal in coagulation–sedimentation processes". Water Research (in English). 42 (18): 4683–4691. Bibcode:2008WatRe..42.4683G. doi:10.1016/j.watres.2008.08.011. ISSN 0043-1354. PMID 18789473.
  8. ↑ Samal, Sneha (2020-04-15). "Effect of shape and size of filler particle on the aggregation and sedimentation behavior of the polymer composite". Powder Technology (in English). 366: 43–51. doi:10.1016/j.powtec.2020.02.054. ISSN 0032-5910. S2CID 213499533.
  9. ↑ Ahmad, Arslan; Rutten, Sam; de Waal, Luuk; Vollaard, Peter; van Genuchten, Case; Bruning, Harry; Cornelissen, Emile; van der Wal, Albert (2020-06-15). "Mechanisms of arsenate removal and membrane fouling in ferric based coprecipitation–low pressure membrane filtration systems". Separation and Purification Technology (in English). 241 116644. doi:10.1016/j.seppur.2020.116644. hdl:1854/LU-8699161. ISSN 1383-5866. S2CID 214445348.
  10. ↑ Nyström, Fredrik; Nordqvist, Kerstin; Herrmann, Inga; Hedström, Annelie; Viklander, Maria (2020-09-01). "Removal of metals and hydrocarbons from stormwater using coagulation and flocculation". Water Research (in English). 182 115919. Bibcode:2020WatRe.18215919N. doi:10.1016/j.watres.2020.115919. ISSN 0043-1354. PMID 32622122. S2CID 219414366.
  11. ↑ Wang, Lawrence K.; Vaccari, David A.; Li, Yan; Shammas, Nazih K. (2005), "Chemical Precipitation", Physicochemical Treatment Processes, Totowa, NJ: Humana Press, pp. 141–197, doi:10.1385/1-59259-820-x:141, ISBN 978-1-58829-165-3
  12. ↑ Wang, Lawrence K.; Fahey, Edward M.; Wu, Zucheng (2005), "Dissolved Air Flotation", in Wang, Lawrence K.; Hung, Yung-Tse; Shammas, Nazih K. (eds.), Physicochemical Treatment Processes (in English), Totowa, NJ: Humana Press, pp. 431–500, doi:10.1385/1-59259-820-x:431, ISBN 978-1-58829-165-3, retrieved 2021-11-12
  13. ↑ Chadha, Utkarsh; Selvaraj, Senthil Kumaran; Vishak Thanu, S.; Cholapadath, Vishnu; Abraham, Ashesh Mathew; Zaiyan, Mohammed; Manikandan, M; Paramasivam, Velmurugan (6 January 2022). "A review of the function of using carbon nanomaterials in membrane filtration for contaminant removal from wastewater". Materials Research Express. 9 (1): 012003. Bibcode:2022MRE.....9a2003C. doi:10.1088/2053-1591/ac48b8. S2CID 245810763.
  14. 1 2 Kurniawan, Tonni Agustiono; Chan, Gilbert Y. S.; Lo, Wai-Hung; Babel, Sandhya (2006-05-01). "Physico–chemical treatment techniques for wastewater laden with heavy metals". Chemical Engineering Journal (in English). 118 (1): 83–98. Bibcode:2006ChEnJ.118...83K. doi:10.1016/j.cej.2006.01.015. ISSN 1385-8947.
  15. 1 2 Armbruster, Dominic; Müller, Uwe; Happel, Oliver (2019). "Characterization of phosphonate-based antiscalants used in drinking water treatment plants by anion-exchange chromatography coupled to electrospray ionization time-of-flight mass spectrometry and inductively coupled plasma mass spectrometry". Journal of Chromatography A. 1601: 189–204. doi:10.1016/j.chroma.2019.05.014. PMID 31130225.
  16. ↑ Vigneswaran, Saravanamuthu; Ngo, Huu Hao; Chaudhary, Durgananda Singh; Hung, Yung-Tse (2005), "Physicochemical Treatment Processes for Water Reuse", Physicochemical Treatment Processes, Totowa, NJ: Humana Press, pp. 635–676, doi:10.1385/1-59259-820-x:635, ISBN 978-1-58829-165-3
  17. ↑ Rengaraj, S; Yeon, Kyeong-Ho; Moon, Seung-Hyeon (October 2001). "Removal of chromium from water and wastewater by ion exchange resins". Journal of Hazardous Materials. 87 (1–3): 273–287. Bibcode:2001JHzM...87..273R. doi:10.1016/s0304-3894(01)00291-6. ISSN 0304-3894. PMID 11566415.
  18. ↑ Singh, N. B.; Nagpal, Garima; Agrawal, Sonal; Rachna (2018-08-01). "Water purification by using Adsorbents: A Review". Environmental Technology & Innovation (in English). 11: 187–240. Bibcode:2018EnvTI..11..187S. doi:10.1016/j.eti.2018.05.006. ISSN 2352-1864. S2CID 103693107.
  19. ↑ BABEL, Sandhya; KURNIAWAN, Tonni Agustiono (2003). "A Research Study on Cr(VI) Removal from Contaminated Wastewater Using Natural Zeolite". Journal of Ion Exchange. 14 (Supplement): 289–292. Bibcode:2003JIEx...14S.289B. doi:10.5182/jaie.14.supplement_289. ISSN 1884-3360.
  20. ↑ Sirotkin, A.; Koshkina, L. Yu.; Ippolitov, K. G. (2001). "The BAC-process for treatment of waste water Containing non-ionogenic synthetic surfactants". Water Research. 35 (13): 3265–3271. Bibcode:2001WatRe..35.3265S. doi:10.1016/S0043-1354(01)00029-X. PMID 11487125.
  21. 1 2 Mezohegyi, Gergo; van der Zee, Frank P.; Font, Josep; Fortuny, Agustí; Fabregat, Azael (2012-07-15). "Towards advanced aqueous dye removal processes: A short review on the versatile role of activated carbon". Journal of Environmental Management (in English). 102: 148–164. Bibcode:2012JEnvM.102..148M. doi:10.1016/j.jenvman.2012.02.021. ISSN 0301-4797. PMID 22459012.
  22. ↑ GracePavithra, Kirubanandam; Jaikumar, V.; Kumar, P. Senthil; SundarRajan, PanneerSelvam (2019-08-10). "A review on cleaner strategies for chromium industrial wastewater: Present research and future perspective". Journal of Cleaner Production (in English). 228: 580–593. Bibcode:2019JCPro.228..580G. doi:10.1016/j.jclepro.2019.04.117. ISSN 0959-6526. S2CID 159345994.
  23. ↑ Gray, Nick (2017-01-31). Water Technology (3 ed.). London: CRC Press. doi:10.1201/9781315276106. ISBN 978-1-315-27610-6.
  24. ↑ "Legislation: The Directive overview". Environment. Brussels: European Commission. 2019-12-31.
  25. ↑ Guidelines for Drinking-water Quality, Fourth Edition; World Health Organization; 2011
  26. ↑ "Environmental quality standards for surface water". Archived from the original on 2018-08-03. Retrieved 2019-11-19.
  27. ↑ What is the purpose of drinking water quality guidelines/regulations?. Canada: Safe Drinking Water Foundation. Pdf. Archived 2011-10-06 at the Wayback Machine
  28. ↑ "Household Water Treatment Guide". Centre for Affordable Water and Sanitation Technology, Canada. March 2008. Archived from the original on 2018-08-09. Retrieved 2011-03-09.
  29. ↑ "Sand as a low-cost support for titanium dioxide photocatalysts". Materials Views. Wiley VCH.
  30. ↑ Lindsten, Don C. (September 1984). "Technology transfer: Water purification, U.S. Army to the civilian community". The Journal of Technology Transfer. 9 (1): 57–59. doi:10.1007/BF02189057. S2CID 154344107.
  31. ↑ "Energy Costs of Water in California". large.stanford.edu. Retrieved 2017-05-07.
  32. ↑ Tuthill, A.H.; Powell, C.A.; Lamb, S; Avery, R.E. "Stainless Steels for Potable Water Treatment Plants". Nickel Institute.
  33. ↑ A.H. Tuthill and S. Lamb. "Guidelines for the use of Stainless Steel in Municipal Waste Water Treatment Plants". Nickel Institute.
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