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![Filtration & Adsorption
▫ Filtration is the physical or mechanical
process of separating solids from
liquids through a membrane.
▫ [Pore sizes of Ultrafiltration: 0.002 –
0.1 microns, Nanofiltration: 0.001
microns, Reverse Osmosis: Removes
everything]
▫ Carbon filtering uses a bed of
activated carbon to remove
contaminants through chemical
adsorption. It is used to remove
organic compounds and free chlorine,
preventing discharge of harmful
byproducts.
33
Water Purification – Stage 2
Filtration
Aeration
▫ Aeration is a process of introducing
air into the water through bubbling.
▫ This is done to reduce the unpleasant
smell and taste by inducing oxidation
of dissolved or suspended metals and
volatile organic chemicals (VOCs).
▫ Dissolved gases such as carbon
dioxide can also be removed through
aeration.
Anaerobic Digestion
▫ Anaerobic Digestion is the introduction
of microorganisms such as bacteria
into the water in order to break down
biodegradable materials.
▫ This process is done with little or no
presence of oxygen, with high
application in wastewater treatment.
▫ It can effectively eliminate pathogens
as well as lowering the Chemical
Oxygen Demand (COD) in the
wastewater.](https://image.slidesharecdn.com/waterslides-180614011403/85/Basics-of-Water-Purification-Methods-33-320.jpg)
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Basics of Water & Purification Methods
- 1.
- 2. “No water, nolife. No blue, no green.” -Sylvia Earle 2
- 3. Content Page 3 WaterBasics Importance of Water ________________________________________________________________________ 05 Presence of Water __________________________________________________________________________ 07 Science of Water ___________________________________________________________________________ 08 Water Cycle _______________________________________________________________________________ 09 Facts & Statistics Global Water Consumption __________________________________________________________________ 11 Water Sources ____________________________________________________________________________ 14 Water Shortage Global Water Crisis _________________________________________________________________________ 22 Water Resource Management Water Management ________________________________________________________________________ 25 Water Conservation ________________________________________________________________________ 26 Water Purification __________________________________________________________________________ 30
- 4. Water Basics Importance ofWater Presence of Water Science of Water Water Cycle
- 5. Importance of Water5 • Drinking* • Daily activities (e.g. showering, cooking) • Household activities • Transportation • Recreational activities (e.g. swimming) • Habitat for flora and fauna • Manufacturing processes • Cleaning, Heating, Cooling • Electricity needs • Wheat & Paddy field • Artificial watering system (e.g. irrigation) Agricultural Industrial DomesticOthers
- 6. 6 Functions of waterin human body1 § Moves nutrients through digestive tract § Fiber absorbs water and allows waste to move through digestive tract § Heat regulator, dissipating body heat through perspiration § Cell waste elimination through urine § Cushion and lubricate body joints § Protects key organs such as brain § Fluid for senses to function properly
- 7. Presence of Water7 § Water covers ¾ of Earth’s surface § 97% from oceans and seas, 2.997% from ice glaciers § Only 0.003% of Earth’s water is readily available freshwater2 § Freshwater sources include groundwater, rivers, lakes, ice glaciers, etc.
- 8. Science of Water8 Forms hydrogen bond with two other water molecules Partial negative charge on hydrogen atom • Partial positive charge on oxygen atom • High heat capacity (4.22 kJ kg-1 K-1) • High latent heat of vaporization (40.63 kJ mol-1) • Latent heat of fusion (6.013 kJ mol-1) • Boiling point (100oC) & Melting point (0oC) at atmospheric pressure Evaporation/ Boiling Melting FreezingCondensation
- 9. Water Cycle 9 evaporation transpiration precipitation Icecap à water storage collection Ocean à Water storage Atmosphere à Water storage condensation
- 10. Facts & Statistics GlobalWater Consumption Water Sources
- 11. 64,000,000,000 m3/year Increase indemand for freshwater globally4 11 Global Water Consumption 35,000,000 km3 Available stock of natural freshwater3
- 12. 575 493 386 374 366 287 193 164 151 149 135 86 46 15 15 4 0 100 200300 400 500 600 700 UNITED STATES AUSTRALIA ITALY JAPAN MEXICO FRANCE GERMANY PHILLIPPINES SINGAPORE UNITED KINGDOM INDIA CHINA KENYA ANGOLA HAITI MOZAMBIQUE Average Water Consumption per capita per day in 2013 (Litres)5 Data by United Nations Development Program 12
- 13. 95 176 114 12120 45 255 1200 0 200 400 600 800 1000 1200 1400 1600 DEVELOPED COUNTRIES DEVELOPINGCOUNTRIES Projection of Water Consumption by sector in 2025 (Cubic kilometer)6 Domestic Industrial Livestock Irrigation 13
- 14. 14 Water Sources Other WaterSources Ø Desalination of seawater (97.5% of Earth’s water) Ø Recycled/ Reclaimed water Frozen Water 68.7% Ground Water 31% Surface Water 0.3% Projected Singapore Water Supply in 20608 Local Catchment & Imported Water Desalinated Water NEWater (Recycled Water) 15% 30% 55% Freshwater Sources7 (2.5% of Earth’s water) Naturally occurring water with low salt content
- 15. 15 Surface Water § Constitutes0.3% of Earth’s freshwater. § Considered readily available and needs to be treated to be potable water. § Non-saline water in river, lake, wetland, etc. § Replenished through water channeled from ocean, aquifers or precipitation. § Lost through evaporation into atmosphere or infiltration into ground. precipitation land runoff infiltration evaporation
- 16. 16 Ground Water § Constitutes31% of Earth’s freshwater. § Needs to be extracted through well or pump and treated to be potable water. § Storage of water underground is called ”Aquifers”, which is made up of sand, rocks and gravel. § Replenished through precipitation or snow melts that infiltrate into cracks under surface of ground. § Can be discharged into surface water sources precipitation infiltration evapotranspiration
- 17. 17 Frozen Water § Constitutes68.7% of Earth’s freshwater. § Rarely used as form of water supply as it requires melting. § Exists as ice and glaciers that mostly remain frozen until today. § Glaciers in mountainous regions form lake basins when the ice masses melt. § Can be replenished as snow at low temperature but will usually melt and result in land runoff. Glaciomarine muds Ice flow Ice shelf melting under ice shelf calved icebergs snowfall
- 18. 18 Desalinated Water § Oceansand seas constitutes 97.5% of Earth’s water. § The highly saline water undergoes desalination to remove the salt and minerals content. § Requires post-treatment to be suitable as potable water. § Energy-intensive process requiring high pressure that incurs huge cost. Seawater intake Pre-treatment (Microfiltration) Reverse Osmosis Post-treatment & Remineralisation
- 19. 19 Recycled Water § Alsoknown as “Reclaimed Water”, which comes from wastewater and greywater. § Can be re-used for household or industrial activities, and even potable water after stringent treatment process. § Possible solution to alleviate global water shortage issue and a freshwater- saving measure. Treated used water Wastewater & Greywater Water reclamation plant Microfiltration Reverse Osmosis Ultraviolet disinfection
- 20. Global application ofrecycled water by sectors9 (After Advanced Treatment) Sector Percentage Application (%) Agricultural irrigation 32.0 Landscape irrigation 20.0 Industrial 19.3 Non-potable urban uses 8.3 Environmental enhancements 8.0 Recreational activities 6.4 Indirect potable reuse 2.3 Groundwater recharge 2.1 Others 1.5 20
- 21. Water Shortage Global WaterShortage Crisis
- 22. Global Water Crisis10 *Variousprominent devastating events included below 22 Deepwater Horizon Oil Spill (2010) Ice caps receding in Alaska (Climate Change) 70% population without clean drinking water in Somalia Jarkata Flooding (2018) Sinkholes & subsidence in San Joaquin Valley Spanish Drought (2017) - Economic water scarcity - Physical water scarcity
- 23. 114,000,000,000$ per year Toachieve Sustainable Development Goal 6 targets on water supply, sanitation & hygiene11 55% Reduction in globally available fresh water per capita since 1960 1,800,000,000 people Lack clean drinking water 23
- 24. Water Resource Management WaterManagement Water Conservation Water Purification
- 25. Water Management Ensure sustainableusage and supply of freshwater for consumption Infrastructure ▫ Building of dams to minimize chances of drought and flood ▫ Regulation of water flow ▫ Can generate electricity and provide recreational venue ✖ May alter ecosystem ✖ Reduce sediment load and transport Rainwater Harvest ▫ Building of water catchment area such as reservoirs ▫ Collection and storage of precipitation ▫ Can provide recreational venue ✖ Requires large land area Desalination ▫ Targeting at 97.5% saline seawater ▫ Removal of salt and minerals from brackish or seawater using distillation/ reverse- osmosis ✖ Very expensive 25
- 26. Water Conservation Reduce consumptionof water in various sectors 26 Industrial Agricultural Municipal
- 27. 27 Municipal Efforts ▫ Recyclingand reusing of household greywater to flush toilets, etc. ▫ Installing water-saving appliances and aerators on sink faucets. ▫ State incentives for water conservation efforts by households.
- 28. Agricultural Efforts ▫ Micro-/Drip-/Trickle-irrigation methodsto be implemented that can conserve water through prevention of over-usage. ▫ Piping of sealed irrigation systems to crops. 28
- 29. Industrial Efforts ▫ Legislationsto prohibit excessive usage of water. ▫ State incentives for water conservation efforts by industries. ▫ Recycling of water within industrial plant process whenever possible. 29 Wastewater tank Clear water tank Water re-injected into industrial process Reactor with filtration
- 30. 30 STAGE 3 Post-treatment (Disinfection) I. Chlorination II.Ozonation III. Ultraviolet Light treatment STAGE 1 Pre-Treatment I. Screening II. Coagulation/ Flocculation III. Sedimentation STAGE 2 Filtration I. Filtration & Adsorption II. Aeration III. Anaerobic Digestion Water Purification Removal or reduction of contaminants in water to meet desired end-use quality requirement
- 31. Screening ▫ The initialstep of treatment is always passing the water through a screen as it enters the treatment plant. ▫ The screen is to remove large natural contaminants such as plants or waste that is big enough. ▫ Screening is not necessary if it the the groundwater to be treated since it has passed through the earth as natural screen. 31 Water Purification – Stage 1 Pre-treatment Coagulation/ Flocculation ▫ Coagulation is either a physical or chemical precipitation of suspended particles in the water to aggregate into larger size, with the use of iron or aluminum salts. ▫ Flocculation is the process whereby colloids in the water precipitate as flakes or flocs after the addition of clarifying agent. ▫ Both aggregate and flocs can be removed during the filtration stage. Sedimentation ▫ As there are many suspended particles in untreated water samples or wastewater, they will start to settle to the bottom of the settling tank as sediments after a while. ▫ The process is slow unless used with external centrifugal force such as hydrocyclone. ▫ The settled sediments can then be removed easily.
- 32. 32 Coagulation/ Flocculation SedimentationScreening Screenmesh Coagulant/ Flocculants Suspended Solids Added with agitation Lighter liquid Heavier sediments Entering Hydrocyclone
- 33. Filtration & Adsorption ▫Filtration is the physical or mechanical process of separating solids from liquids through a membrane. ▫ [Pore sizes of Ultrafiltration: 0.002 – 0.1 microns, Nanofiltration: 0.001 microns, Reverse Osmosis: Removes everything] ▫ Carbon filtering uses a bed of activated carbon to remove contaminants through chemical adsorption. It is used to remove organic compounds and free chlorine, preventing discharge of harmful byproducts. 33 Water Purification – Stage 2 Filtration Aeration ▫ Aeration is a process of introducing air into the water through bubbling. ▫ This is done to reduce the unpleasant smell and taste by inducing oxidation of dissolved or suspended metals and volatile organic chemicals (VOCs). ▫ Dissolved gases such as carbon dioxide can also be removed through aeration. Anaerobic Digestion ▫ Anaerobic Digestion is the introduction of microorganisms such as bacteria into the water in order to break down biodegradable materials. ▫ This process is done with little or no presence of oxygen, with high application in wastewater treatment. ▫ It can effectively eliminate pathogens as well as lowering the Chemical Oxygen Demand (COD) in the wastewater.
- 34. 34 Filtration & AdsorptionAeration Anaerobic Digestion Search (Week 2) ng ARBON FILTER: ering uses a bed of activated carbon to remove contaminants through chemical . In water treatment, activated carbon filters are used to remove organic s and free chlorine so as to prevent discharge of harmful byproducts between nd acids such as humic and fulvic acid. (WaterProfessionals, 2014) Therefore, d taste would be greatly reduced after treatment with activated carbon filter. activated carbon is unable to remove hardness, sodium, fluorides, nitrates and As the water passes through the filter, particles are trapped within the carbon this process is known as adsorption. Activated carbon has slightly positive charge s it to act as an ion exchanger to remove impurities. Motor Settling chamber Aspiration mixer
- 35.
- 36. Chlorination ▫ Chlorine gasis water-soluble and rapidly hydrolyzes to hypochlorous acid (HOCl) and hypochlorite ion (OCl-), where the former is 20 times more germicidal. ▫ Chlorine destroys microorganisms by corroding the cell membrane. It is then capable of penetrating and destroying the cells after the membrane is weakened, by disrupting respiration and DNA activity. 36 Water Purification – Stage 3 Post-treatment Ozonation ▫ Ozone is a very strong oxidizing agent and is unstable in its form, therefore it must be generated on-site that involves passing dry air through high- voltage electrical discharge or by UV radiation. It can also be generated with electrolytic and chemical reactions. ▫ Due to its high oxidation potential, ozone can easily disintegrate the cell wall (process known as lysis) of the microorganisms by dissociating the double bonds of the fatty acids in the cell wall. Thereafter, the ozone continues to oxidize enzymes and DNA within the cell and finally destroying it. Ultraviolet Light Treatment ▫ Ultraviolet (UV) has a wavelength ranging from 10nm to 400nm, with those between 200nm and 300nm (UV- C) having capability of effective germicidal irradiance . ▫ UV inactivates microorganisms through physical process with photochemical damage of the nuclei acids (DNA & RNA) due to the high energy of UV with typical wavelength at 254nm. New chemical bonds are formed between adjacent nucleotides, resulting in double bonds or dimers. Formation of dimers prevents replication from happening and hence inactivating the microorganisms.
- 37. 37 Chlorination Ozonation Ultraviolet Light Treatment INTRODU Slide2 Water Disinfection byU U ge di ca A A th ab tr th Principles & Mechanisms: Chlorine destroys microorganisms by corroding the cell membrane. It is then capable of penetrating and destroying the cells after the membrane is weakened, by disrupting respiration and DNA activity. This results in the microorganisms unable to multiply and eventually die. What it can remove: Chlorine treatment is effective against bacteria and viruses, but not all water-borne pathogens. Certain protozoa cysts (Giardia and Cryptosporidium) have developed resistance to chlorine. The mentioned protozoa can be removed with other disinfectant such as ozone and chlorine dioxide. Chlorine-based disinfectants can also remove micro-pollutants such as pesticides. Advantages: • More cost-effective than UV or ozone treatment • Presence of disinfectant residual in the effluent that prolong disinfection • Can oxidize certain organic and inorganic compounds • Dosage of chlorine is flexible and customizable Limitations: • Chlorine disinfectant residual is toxic to aquatic life • Additional dechlorination step to remove residual • Highly corrosive and therefore poses risk in handling • By-products from oxidation may create more harmful compounds • Total dissolved solids increase after treatment Literature Search (Week 1) – Water Disinfection Ee Liang Ying Ozone Treatment What it is: Ozone is a very strong oxidizing agent and is unstable in its form, therefore it must be generated on-site that involves passing dry air through high-voltage electrical discharge or by UV radiation. It can also be generated with electrolytic and chemical reactions. This treatment method can be used at various points of the whole treatment system, but usually pre- filtration stage. Principles & Mechanisms: Due to its high oxidation potential, ozone can easily disintegrate the cell wall (process known as lysis) of the microorganisms by dissociating the double bonds of the fatty acids in the cell wall. Thereafter, the ozone continues to oxidize enzymes and DNA within the cell and finally destroying it. What it can remove: Ozone is a broad range biocide that can inactivate all pathogenic organisms including bacteria, viruses and protozoa. It can also remove certain heavy metals, organic and inorganic matter,
- 38. 38 dark repair Comparison with other disinfection methods (International Water-Guard, 2002): (Favourable characteristics are in green font) Disinfection Methods Ultraviolet (UV) Biocides* Ozone Mechanics Physical Chemical Chemical Capital Cost Low Medium High Operation Cost Low Medium High Maintenance Cost Low Medium High Maintenance Frequency Low Medium High Disinfection Performance High Good Unpredictable Literature Search (Week 2) Ee Liang Ying Contact Time 1 – 10 seconds 15 – 45 minutes 5 – 10 minutes Staff Hazards Low Medium High Toxic Chemicals No Yes Yes Water Chemistry Changes No Yes Yes Residual Disinfectant No Yes Yes Influenced by pH & temperature No Yes Yes *Biocides: Chlorine, sodium hypochlorite, calcium hypochlorate, chlorine dioxide, bromine, etc. Ways of producing UV-light (Sciencedirect, 2017):
- 39. 39 THANK YOU! References 1. Laskey, J.(2015, February 16). The Health Benefits of Water. Retrieved May 10, 2018, from Everyday Health: https://www.everydayhealth.com/water-health/water-body- health.aspx 2. Everything Connects. (2013, November 20). Fresh Water. Retrieved May 10, 2018, from Everything Connects: http://www.everythingconnects.org/fresh-water.html 3. Gleick, P. H., & Palaniappan, M. (2010, June 22). Peak water limits to freshwater withdrawal and use. PNAS, 107, 11155 - 11162. 4. UNESCO. (2009, March 12). New report highlights crucial role of water in development. Retrieved May 21, 2018, from UNESCO: http://www.unesco.org/new/en/media- services/single- view/news/new_report_highlights_crucial_role_of_water_in_development/ 5. Watkins, K. (2006, May). Human Development Report 2006. New York: United Nations Development Programme. Retrieved from Data360: http://www.data360.org/dsg.aspx?Data_Set_Group_Id=757 6. Rosegrant, M. W., Cai, X., & Cline, S. A. (2002). Global Water Outlook To 2025. International Food Policy Research Institute. Colombo: International Food Policy Research Institute. 7. PUB. (2018, January 01). Singapore Water Story. Retrieved May 28, 2018, from Public Utilities Board: https://www.pub.gov.sg/watersupply/singaporewaterstory 8. Koncagul, E., Tran, M., Connor, R., Uhlenbrook, S., & Ortigara, A. R. (2017). The United Nations World Water Development Report 2017. Italy: United Nations World Water Assessment Programme. 9. Gleick, P. H. (1996). Water resources. In P. H. Gleick, In Encyclopedia of Climate and Weather (pp. 817 - 823). New York: Oxford University Press. Retrieved from blueplanet: http://www.blueplanet.nsw.edu.au/mi--water--distribution-of-water/.aspx 10. WaterWoes. (2001, April 26). Where's the water? Retrieved June 02, 2018, from Water Woes: https://whyfiles.org/131fresh_water/index.html 11. Guppy, L., & Anderson, K. (2017). Global Water Crisis: The Facts. Canada: UNU-INWEH.