Drinking water Drinking water Water pollutionWater pollution

• Water is HWater is H22OO

Water

• is a tasteless, odourless, appearing colourless is a tasteless, odourless, appearing colourless for naked eye substance that is essential to all for naked eye substance that is essential to all known forms of life.known forms of life.

• is a universal is a universal solventsolvent..• seawaterseawater (97%) has (97%) has salinitysalinity of minimum of minimum 3.5%3.5%

(35grams of sodium chloride mostly per 1 litre of (35grams of sodium chloride mostly per 1 litre of water).water).

• freshwater (3%) freshwater (3%) contains less than contains less than 0.5parts 0.5parts per thousandper thousand dissolved dissolved saltssalts. It is . It is surface surface waterwater (0.3%) in (0.3%) in lakes, riverslakes, rivers and underground and underground as as groundwatergroundwater. Majority of freshwater is frozen . Majority of freshwater is frozen in glaciers and ice caps. in glaciers and ice caps.

Chemical and physical properties of Chemical and physical properties of water (Hwater (H22O)O)

• Water strongly Water strongly absorbs infrared radiationabsorbs infrared radiation. This . This results in pure water appearing slightly blue.results in pure water appearing slightly blue.

• Water is a Water is a very good solvent for hydrophilic very good solvent for hydrophilic (‘water loving’) substances.(‘water loving’) substances.

• Water sticks to itself Water sticks to itself (cohesion)(cohesion) because it is because it is polar.polar.

• Water has a Water has a high surface tensionhigh surface tension caused by caused by strong cohesion between water moleculesstrong cohesion between water molecules

Chemical and physical properties of Chemical and physical properties of water (Hwater (H22O)O)

• Water is able to move up narrow tube against Water is able to move up narrow tube against the force of gravity (the force of gravity (capillary actioncapillary action).).

• Water is able to moderate Earth’s climate by Water is able to moderate Earth’s climate by buffering large swings of temperature as it has buffering large swings of temperature as it has high heat capacityhigh heat capacity and and high heat of high heat of vaporization.vaporization.

• Freezing pointFreezing point. Ice floats on the water. Fresh . Ice floats on the water. Fresh water at standard atmospheric pressure water at standard atmospheric pressure is most is most dense at 3.98°C.dense at 3.98°C. This keeps deep water to This keeps deep water to remain warmer than shallow freezing water and remain warmer than shallow freezing water and this is how fish can survive freezing this is how fish can survive freezing temperatures in the water.temperatures in the water.

Chemical and physical properties of Chemical and physical properties of water (Hwater (H22O)O)

• Triple point Triple point is a single combination of is a single combination of pressure and temperature at which pure pressure and temperature at which pure liquid water, ice and water vapour can liquid water, ice and water vapour can coexist in a stable equilibrium = 0.01°C coexist in a stable equilibrium = 0.01°C and 611.73 pascals.and 611.73 pascals.

• Any Any electrical conductivityelectrical conductivity observable in observable in water are from ions dissolved in it.water are from ions dissolved in it.

Water purity refers to purity from:Water purity refers to purity from:

• toxinstoxins

• microbesmicrobes

• pollutantspollutants

Drinking water Drinking water (potable water)(potable water)

• Is fit for human consumption.Is fit for human consumption.

• Must be pure from toxins, pollutants and Must be pure from toxins, pollutants and microbes.microbes.

• Must be easily available.Must be easily available.

Bacterial water analysisBacterial water analysis

• Is a Is a routine checkroutine check to make sure that the to make sure that the concentration of potentially pathogenic bacteria concentration of potentially pathogenic bacteria in drinking water is sufficiently low to say it is in drinking water is sufficiently low to say it is safe for human consumption.safe for human consumption.

• Three Three indicator bacteriaindicator bacteria are chosen: are chosen: non-non-specific coliforms, Escherichia coli and specific coliforms, Escherichia coli and Pseudomonas aeruginosa.Pseudomonas aeruginosa.

• ColiformsColiforms (esp. E. Coli) could suggest the (esp. E. Coli) could suggest the possibility of possibility of fecal matter contaminationfecal matter contamination of a of a water supply.water supply.

• Coliform IndexColiform Index is usually given as a measure is usually given as a measure of human fecal matter in the water. of human fecal matter in the water.

Escherichia coliEscherichia coli

• Escherichia coli is Escherichia coli is an indicator an indicator bacteriabacteria. Its presence . Its presence in water supply could in water supply could suggest the possibility suggest the possibility of faecal matter of faecal matter contamination of a contamination of a water supply. Such water supply. Such water cannot be used water cannot be used for drinkingfor drinking

Drinking water purificationDrinking water purification

• Is removal of contaminants from raw water Is removal of contaminants from raw water to produce drinking water that is pure to produce drinking water that is pure enough for human consumption or for enough for human consumption or for industrial use. industrial use.

• Substances that are removed are: Substances that are removed are: parasites (Giardia, Cryptosporidium), parasites (Giardia, Cryptosporidium), bacteria, algae, viruses, fungi, minerals bacteria, algae, viruses, fungi, minerals (lead, copper), man-made chemical (lead, copper), man-made chemical pollutants.pollutants.

Sources of drinking waterSources of drinking water

• Deep groundwaterDeep groundwater-is generally of very high -is generally of very high biological quality, but may be rich in dissolved biological quality, but may be rich in dissolved solids, especially carbonates, sulphates of solids, especially carbonates, sulphates of calcium and magnesium. calcium and magnesium.

• Shallow groundwaterShallow groundwater is usually abstracted is usually abstracted from wells or boreholes. Its’ bacterifrom wells or boreholes. Its’ bacterioological logical quality is variable. A variety of soluble material quality is variable. A variety of soluble material may be present in it.may be present in it.

• Upland lakes and reservoirsUpland lakes and reservoirs-bacteria and -bacteria and pathogen levels are usually low.pathogen levels are usually low.

Sources of drinking waterSources of drinking water

• Rivers, canals and low land reservoirsRivers, canals and low land reservoirs--will have a significant bacterial load.will have a significant bacterial load.

• Atmospheric water generationAtmospheric water generation- is a new - is a new technology that can provide high quality technology that can provide high quality drinking water by extracting water from air drinking water by extracting water from air by condensing water vapour.by condensing water vapour.

• Rainwater harvesting or fog collectionRainwater harvesting or fog collection- - can be used in areas especially with can be used in areas especially with significantly dry seasons.significantly dry seasons.

Water treatmentWater treatment

• Primary treatmentPrimary treatment- collecting, screening and - collecting, screening and initial storage.initial storage.

• Secondary treatmentSecondary treatment- removal of fine solids - removal of fine solids and the majority of contaminants using filters, and the majority of contaminants using filters, coagulation, flocculation and membranes.coagulation, flocculation and membranes.

• Tertiary treatmentTertiary treatment-polishing, pH adjustment, -polishing, pH adjustment, carbon treatment to remove taste and smell, carbon treatment to remove taste and smell, disinfectiondisinfection, and temporary storage., and temporary storage.

Water disinfectionWater disinfection

• Means destroying any living pathogens Means destroying any living pathogens ((viruses, bacteriaviruses, bacteria including E. coli, including E. coli, Campylobacter, Shigella, Campylobacter, Shigella, protozoans protozoans including Giardia lamblia and including Giardia lamblia and Cryptosporidia).Cryptosporidia).

Means used for water disinfectionMeans used for water disinfection

• ChlorineChlorine- the most commonly used. A major - the most commonly used. A major drawback to using chlorine is that it reacts with drawback to using chlorine is that it reacts with organic compounds in the water to form organic compounds in the water to form potentially harmful potentially harmful trihalomethanes (THMstrihalomethanes (THMs) ) and and haloacetic acidshaloacetic acids, both of which are , both of which are carcinogeniccarcinogenic. .

• Chlorine dioxideChlorine dioxide• ChloraminesChloramines• OzoneOzone• UV radiationUV radiation

Water treatment optionsWater treatment options

• FluoridationFluoridation to prevent to prevent tooth decaytooth decay..• Water conditioning to reduce the effects of Water conditioning to reduce the effects of hard hard

waterwater. Water hardness is content of . Water hardness is content of calcium calcium and magnesium carbonateand magnesium carbonate dissolved in it. dissolved in it.

• Plumbo- solvency reductionPlumbo- solvency reduction- in some - in some locations water is capable of dissolving locations water is capable of dissolving lead lead from any lead pipes that it is carried in. Lead is from any lead pipes that it is carried in. Lead is toxic.toxic.

• Radium removal.Radium removal.• Fluoride removal.Fluoride removal.

Other water purification techniquesOther water purification techniques

• BoilingBoiling for three minutes to disinfect for three minutes to disinfect water.water.

• Charcoal filteringCharcoal filtering allows to remove many allows to remove many compounds including toxins.compounds including toxins.

• DistillationDistillation -involves boiling to produce -involves boiling to produce vapour and then condensing it. Distillation vapour and then condensing it. Distillation does not completely purify water. The does not completely purify water. The distillation apparatus may be the ideal distillation apparatus may be the ideal place to harbour place to harbour Legionella Legionella ..

WastewaterWastewater

• Is any water that has been adversely Is any water that has been adversely affected in quality by antropogenic affected in quality by antropogenic influence. It comprises liquid waste influence. It comprises liquid waste discharged by domestic residences, discharged by domestic residences, commercial properties, industry and commercial properties, industry and agriculture .agriculture .

SewageSewage

• is the subset of wastewater that is is the subset of wastewater that is contaminated with faeces or urine.contaminated with faeces or urine.

Wastewater constituentsWastewater constituents

• WaterWater >95%. >95%.• PathogensPathogens: bacteria, viruses, prions, parasites.: bacteria, viruses, prions, parasites.• Non- pathogenic bacteria.Non- pathogenic bacteria.• Organic particlesOrganic particles (faeces, hairs, food, paper, (faeces, hairs, food, paper,

plant material).plant material).• Soluble organic materialSoluble organic material (urea, fruit sugars, (urea, fruit sugars,

protein, drugs).protein, drugs).• Inorganic particlesInorganic particles ( sand, metal particles, ( sand, metal particles,

ceramics).ceramics).

Wastewater constituentsWastewater constituents

• Soluble inorganic materialSoluble inorganic material (ammonia, road- (ammonia, road-salt, cyanide, hydrogen sulphide).salt, cyanide, hydrogen sulphide).

• AnimalsAnimals (protozoa, insects, arthropods, small (protozoa, insects, arthropods, small fish).fish).

• Macro-solidsMacro-solids (sanitary towels, diapers, (sanitary towels, diapers, condoms).condoms).

• GasesGases (hydrogen sulphide, carbon dioxide and (hydrogen sulphide, carbon dioxide and methane).methane).

• EmulsionsEmulsions (paint, adhesives, mayonnaise). (paint, adhesives, mayonnaise).• ToxinsToxins (pesticides, poisons). (pesticides, poisons).

Biochemical Oxygen Demand Biochemical Oxygen Demand (BOD)(BOD)

• Is a Is a wastewater quality indicatorwastewater quality indicator. . • Any oxidizable material present in a natural Any oxidizable material present in a natural

waterway or in an industrial wastewater will be waterway or in an industrial wastewater will be oxidized by both biochemical (bacterial) or oxidized by both biochemical (bacterial) or chemical processes. The result is that the chemical processes. The result is that the oxygen content of the water will decreaseoxygen content of the water will decrease

• Oxidizable material+ bacteria+ nutrient +OOxidizable material+ bacteria+ nutrient +O22-› -› COCO22+ H+ H22O+ oxidized inorganics such as NOO+ oxidized inorganics such as NO33 or SOor SO44..

Chemical Chemical Oxygen Demand (COD)Oxygen Demand (COD)

• Oxidizable chemicals (such as reducing Oxidizable chemicals (such as reducing chemicals) introduced into a natural water will chemicals) introduced into a natural water will initiate chemical reactions. Those chemical initiate chemical reactions. Those chemical reactions create what is measured as Chemical reactions create what is measured as Chemical Oxygen Demand.Oxygen Demand.

• Both BOD and COD tests are a measure of Both BOD and COD tests are a measure of relative oxygen-depletion effect of a waste relative oxygen-depletion effect of a waste contaminant. Both have been widely adopted as contaminant. Both have been widely adopted as a measure of pollution effecta measure of pollution effect..

5-day BOD5-day BOD

• Measures the amount of oxygen Measures the amount of oxygen consumed by biochemical oxidation of consumed by biochemical oxidation of waste contaminants in a 5-day period.waste contaminants in a 5-day period.

• Oxidizable chemicals (such as reducing Oxidizable chemicals (such as reducing chemicals) introduced into a natural water will chemicals) introduced into a natural water will initiate chemical reactions. Those chemical initiate chemical reactions. Those chemical reactions create what is measured as Chemical reactions create what is measured as Chemical Oxygen Demand.Oxygen Demand.

• Both BOD and COD tests are a measure of Both BOD and COD tests are a measure of relative oxygen-depletion effect of a waste relative oxygen-depletion effect of a waste contaminant. Both have been widely adopted as contaminant. Both have been widely adopted as a measure of pollution effecta measure of pollution effect..

Wastewater treatmentWastewater treatment

• Most wastewater is treated in Most wastewater is treated in wastewater wastewater treatment plantstreatment plants which include which include physical, physical, chemical and biologicalchemical and biological treatment treatment processes.processes.

Wastewater reuseWastewater reuse

• Treated wastewater can be reused as Treated wastewater can be reused as drinking water (Singapore), drinking water (Singapore),

• in industry (cooling towers), in industry (cooling towers), • in artificial recharge of aquifiers, in artificial recharge of aquifiers, • in agriculture (70% in agriculture (70% oof Israel’s irrigated f Israel’s irrigated

agriculture is based on highly purified agriculture is based on highly purified wastewater),wastewater),

• in rehabilitation of natural ecosystems in rehabilitation of natural ecosystems ((FFlorida’s Everglades). lorida’s Everglades).