water as factor of health, its hygienic, endemic and epidemiologic value. organization of drinkable...
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Water as factor of health, its Water as factor of health, its hygienic, endemic and hygienic, endemic and
epidemiologic value. Organization epidemiologic value. Organization of drinkable water-supply. of drinkable water-supply.
Methods of improvement of quality Methods of improvement of quality of drinking-water. Ecological of drinking-water. Ecological
problems and sanitary protection problems and sanitary protection of objects of waters.of objects of waters.
The lectureThe lecture
Author: Lototska O.V.Author: Lototska O.V.
Its main functions are that it:Its main functions are that it: Replaces loss of fluids from Replaces loss of fluids from
tissues.tissues. Maintains the fluidity of blood and Maintains the fluidity of blood and
lymph.lymph. Helps elimination of waste material Helps elimination of waste material
of the body.of the body. Acts as a vehicle for dissolved Acts as a vehicle for dissolved
food.food. Helps in the secretion of digestive Helps in the secretion of digestive
juices.juices. Regulates body temperature and Regulates body temperature and
acts as a distributor of body heat.acts as a distributor of body heat.
Water constitutes nearly two-thirds of the total weight Water constitutes nearly two-thirds of the total weight of the body, 79 % of blood, 80 % of brain and muscles of the body, 79 % of blood, 80 % of brain and muscles and 10 % even of bonesand 10 % even of bones
Uses of water
Domestic Use: 7 % of water available is for domestic use i.e drinking, cooking, washing, bathing etc. Recommended need of water is 30 gallon/ day/ person. It includes all aspects of life which a person has in his routine life i.e bathing, washing, drinking & for toilet use.
Public purpose: Water is required for public cleansing, maintenance of gardens, and swimming pools and other civic activities.
Industrial Use: 23 % of available water is used in industries.
Agricultural Use: 70 % of available water is used for growth of food and raw materials required.
WatersWaters,, used for drink and everyday needs, used for drink and everyday needs, must correspond to the demands: must correspond to the demands:
good organoleptic properties: refreshing temperature, transparence, colorless, no smell and no taste . harmlessness of its chemical composition the absence of pathogenic microorganismssafety in the radiological attitude
The population should be provided not The population should be provided not only with enough of water, but also only with enough of water, but also with qualitative water. Water should with qualitative water. Water should not cause any pathological change in not cause any pathological change in the organism, should not cause of the organism, should not cause of spread of infectious diseases, and also spread of infectious diseases, and also not to cause unpleasant sensations.not to cause unpleasant sensations.
Sources of waterSources of water
RAINPrime source of all water.
Part of rain water sinks to form ground water, part of it evaporates and some runs in streams and rivers. These events are called "water - cycle".
Characteristics:Purest, bright & sparkling colour, soft water, only traces of dissolved solids, corrosive action on lead due to softness, in clean areas rain water is free of pathogens.
Impurities:Picks up local impurities such as dust, soot, micro-organisms, CO2, N2, O2, Ammonia & Sulphur. In areas where NO2 and SO2 are present in atmosphere, rain water becomes acidic and the rain is called acidic rain.
SURFACE WATERSurface water mostly originates from rain water.It has highest chance of being polluted particularly river water because people near banks throw wastes in it.Sources of surface water are.a. Impounding reservoirsb. Rivers and streamsc. Tanks, ponds and lakes.
Catchments Area;It is an area from where rain water is drained into a specific reservoir area made naturally/ artificially.
Peat:Decomposed organic matter containing acids is called peat. It makes water acidic, so gain ability to dissolve lead and result is lead poisoning.
GROUND WATERIt is in form of:
a. Wells — Deep well, shallow well, Artesian well.b. Springs — Seasonal springs, thermal springs, mineral
spring, shallow springs, and deep springs.
The advantages of ground water are:a. It is usually free from pathogenic agents.b. It usually requires no treatment.c. Its supply is continuous.
The disadvantages of ground water are:a. It is high in mineral contentsb. It requires pumping or some arrangement to lift the
water.Springs: A spring is ground water which finds its way to
the surface because of topographical features. Cracks present in earth, water enters and comes out from other opening at a low level. So source may be quite far away such as 100-200 miles.
WELLSWELLS
These are artificial holes or pits dug into the earth to These are artificial holes or pits dug into the earth to reach the underground water level. They constitute a very reach the underground water level. They constitute a very important source of water supply in villages. There are important source of water supply in villages. There are four varieties of wells:four varieties of wells: 1. 1. Shallow WellsShallow Wells,,2. 2. Deep WellsDeep Wells3. 3. Artesian WellsArtesian Wells are a variety of deep wells in which are a variety of deep wells in which water under great pressure comes out to the surface water under great pressure comes out to the surface automaticallyautomatically 4. 4. Norton's Abyssinian Tube WellsNorton's Abyssinian Tube Wells are really shallow wells are really shallow wells which are bored by simply driving iron pipes 3.8 to 5 cm. which are bored by simply driving iron pipes 3.8 to 5 cm. in diameter and 6 to 7.62 metres deep to tap thein diameter and 6 to 7.62 metres deep to tap the ground ground
water. A pump is attached to the pipe to draw the water.water. A pump is attached to the pipe to draw the water.
Types of aquifers and wells.
In a water table well, the water table is at atmospheric pressure. In an artesian well, the water pressure is greater than atmospheric. In a flowing artesian well, the water pressure is such that it can flow freely above the ground surface
The pollution of water sources represents the The pollution of water sources represents the important ecological problem. Depending on important ecological problem. Depending on type of pollution there are: type of pollution there are:
chemical, chemical, physical (radioactive substances, hot water), physical (radioactive substances, hot water), bacterial, virus and biological. bacterial, virus and biological. Industrial wastewater is characterized by Industrial wastewater is characterized by
considerable quantity of components.considerable quantity of components.
Major categories of water pollutantMajor categories of water pollutant 1. Infections agents - Bacteria, viruses 2. Organic chemical - Pesticides, plastics,
detergents, oil, and gasoline 3. Inorganic chemicals - Acids, caustics, salts,
metals 4. Radioactive materials - Uranium, thorium,
cesium, iodine, radon
Hazards of Polluted Water:1. Biological HazardsThese are due to some specific agent that causes ill-
health.
Bacterial Typhoid, Bacillary dysentery, Typhoid, Bacillary dysentery, Cholera etc.Cholera etc.
Viral Viral hepatitis A & E, Viral hepatitis A & E, Poliomyelitis.Poliomyelitis.
Protozoal Amoebiasis, Giardiasis.Amoebiasis, Giardiasis.
Helminthic Round worm, whip worm, Round worm, whip worm, hydatid diseasehydatid disease
Leptospiral Weil's diseaseWeil's disease
Cyclops Guinea worm.Guinea worm.
2. Other Hazards
a. GIT disturbances due to Na ++, Mg ++ & Ca++ ions, e.g) increased MgSO4 lead to
diarrhea.b. Lead poisoning c. Iodine deficiencyd. Fluorine deficiencye. Hardness of waterf. Infant methaemoglobinemia.
Impure water may be purified by either of the following methods:
A. NaturalA. Natural (a) Pounding or Storage.(a) Pounding or Storage. (b) Oxidation and Settlement.(b) Oxidation and Settlement.
B. ArtificialB. Artificial I. PhysicalI. Physical Distillation.Distillation. Boiling.Boiling.II. ChemicalII. Chemical Precipitation.Precipitation. Disinfection or Sterilization.Disinfection or Sterilization.III. FiltrationIII. Filtration "Biological" or "Slow Sand" Filtration."Biological" or "Slow Sand" Filtration. "Rapid Sand" or "Mechanical" Filtration."Rapid Sand" or "Mechanical" Filtration. Domestic Filtration.Domestic Filtration.
PURIFICATION OF WATERPURIFICATION OF WATERPurification of water is of great Purification of water is of great
importance in community medicine. It importance in community medicine. It may be considered under two headings.may be considered under two headings.
Purification of water on large scalePurification of water on large scale Purification of water on small scalePurification of water on small scale
Three main steps in purification Three main steps in purification of water on large scale:of water on large scale:
Storage, Filtration, ChlorinationStorage, Filtration, Chlorination
1. Storage:1. Storage:Water is drawn out from source and Water is drawn out from source and
impounded in natural or artificial reservoirs. impounded in natural or artificial reservoirs. Storage provides a reserve of water from which Storage provides a reserve of water from which further pollution is excluded.further pollution is excluded.
AdvantagesAdvantages Physical Physical — About 90% of suspended impurities — About 90% of suspended impurities
settle down in 24 hours by gravity.settle down in 24 hours by gravity. Chemical Chemical — The aerobic bacteria oxidize the — The aerobic bacteria oxidize the
organic matter present in water with the aid of organic matter present in water with the aid of dissolved oxygen. As a result the content of free dissolved oxygen. As a result the content of free ammonia is reduced and a rise in nitrates occur.ammonia is reduced and a rise in nitrates occur.
Biological Biological — 90 % of total bacterial count drops in — 90 % of total bacterial count drops in first 5 - 7 days.first 5 - 7 days.
2. Filtration2. FiltrationFiltration is important because Filtration is important because
98 – 9998 – 99 % of bacteria are removed by % of bacteria are removed by filtration, a part from other impurities. filtration, a part from other impurities. Two types of filters are in use, they are:Two types of filters are in use, they are:
a.a. Slow sand filters (biological Slow sand filters (biological filters)filters)
b.b. Rapid sand filters (Mechanical Rapid sand filters (Mechanical filters)filters)
Slow sand filterSlow sand filter
Supernatant (raw) water:
Sand bed
Vital Layer
Under - drainage system
Filter control valves:Filter control valves:
The filter is equipped with certain valves and The filter is equipped with certain valves and devices which are incorporated in the outlet pipe devices which are incorporated in the outlet pipe system maintaining a steady rate of filtration.system maintaining a steady rate of filtration.
When the vital layer becomes dense and When the vital layer becomes dense and resistance to the passage of water is increased the resistance to the passage of water is increased the supernatant water is drained off Sand bed is supernatant water is drained off Sand bed is cleaned by scrapping of the top portion of the sand cleaned by scrapping of the top portion of the sand layer to a depth of 1 - 2 cms. Scrapping is done 20 - layer to a depth of 1 - 2 cms. Scrapping is done 20 - 30 times. 30 times.
The process is known as The process is known as Filter CleaningFilter Cleaning..
b. Rapid Sand Filterb. Rapid Sand FilterRapid sand filters are of two types, Rapid sand filters are of two types,
the gravity type and the pressure type. the gravity type and the pressure type. Both the types are in use. The following Both the types are in use. The following steps are involved in the purification of steps are involved in the purification of water by rapid sand filters.water by rapid sand filters.
i. Coagulation:i. Coagulation:
ii. Rapid mixing:ii. Rapid mixing:
iii. Flocculation:iii. Flocculation:
iv. Sedimentation:iv. Sedimentation:
v. Filtration:v. Filtration:
A complete system of water supply
Filter Beds:Filter Beds:
Back - Washing:Back - Washing:Rapid sand filters need frequent washing daily or Rapid sand filters need frequent washing daily or
weekly. Washing is accomplished by reversing the flow of weekly. Washing is accomplished by reversing the flow of water through the sand bed, which is called "back-washing". water through the sand bed, which is called "back-washing". Back - washing dislodges the impurities and cleans up the Back - washing dislodges the impurities and cleans up the sand bed.sand bed.
Comparison of Rapid & Slow Sand Filters.
Slow Sand Filter Rapid Sand Filter
Space Occupies large space Occupies very little area
Rate of filtration 0.1 -0.4 m3/m2/h 5- 15 m3/m2/h
Effective size of sand 0.15-0.35 mm 0.6 - 2.0 mm
Preliminary treatment
Plain sedimentation Chemical coagulation
Washing By Scraping the sand bed
By back-washing
Operations Less skilled Highly skilled
Removal of turbidity Good Good
Removal of colour fair Good
Removal of bacteria 99.9-99.99 per cent 98 - 99 per cent
Advantages of Slow Sand Filter
Advantages of Rapid Sand filter
1. Simple to construct and operate
1. It deals with raw water directly. No. preliminary storage is needed
2. Cost of construction is cheaper
2. Occupies less space.
3. Physical, Biological and Chemical quality ' of filtered water is very high
3. Filtration rate is high.
4. Washing of filter is easy
5. More flexibility in operation.
CHLORINATIONCHLORINATIONChlorination is the process in which chlorine is Chlorination is the process in which chlorine is
added to water for purification. Chlorinationadded to water for purification. Chlorination is more is more effective when pH of water is around 7.effective when pH of water is around 7.
Effects of Chlorine:Effects of Chlorine:
a.a. Chlorine kills pathogenic bacteria, it has no effect on Chlorine kills pathogenic bacteria, it has no effect on spores and certain viruses.spores and certain viruses.
b.b. It has germicidal effects.It has germicidal effects.
c.c. It oxidizes iron, manganese and Hydrogen sulphide It oxidizes iron, manganese and Hydrogen sulphide
d.d. If destroys some taste and odour producing If destroys some taste and odour producing constituents.constituents.
e. e. It controls algae and slim organismsIt controls algae and slim organisms
f.f. It aids coagulation It aids coagulation
Action of ChlorineAction of Chlorine
When Chlorine is added to water, there is When Chlorine is added to water, there is formation of hypochlorous and hydrochloric formation of hypochlorous and hydrochloric acid. The hydrochloric acid is neutralised by acid. The hydrochloric acid is neutralised by alkalinity of the water. The hypochlorous acid alkalinity of the water. The hypochlorous acid ionizes to form hydrogen ions and hypochlorite ionizes to form hydrogen ions and hypochlorite ions as follows.ions as follows.
HH22O + CIO + CI22 ► HCI--+HOCI► HCI--+HOCIHOCI HOCI ► H++OCI“► H++OCI“
The disinfecting action of-chlorine is mainly due The disinfecting action of-chlorine is mainly due to hypochlorous acid and to a small extent due to hypochlorous acid and to a small extent due to hypochloriteon.to hypochloriteon.
Principles of Chlorination
a. First, water should be clear and free First, water should be clear and free from turbidity.from turbidity.b.b. Chlorine Chlorine absorption absorption ((demanddemand)) of water of water should be estimated.should be estimated.c.c. At least one hour is essential as a At least one hour is essential as a contact period of contact period of free residual chlorinefree residual chlorine for for killing bacterial and viruses.killing bacterial and viruses.d.d. Minimum recommended concentration Minimum recommended concentration of free of free residual chlorineresidual chlorine is is 0,3 - 0,3 - 0.5 mg/L.0.5 mg/L.e.e. The sum of the chlorine absorption of The sum of the chlorine absorption of water and the quantity of residual chlorine water and the quantity of residual chlorine (0,3-0,5 mg/l) is the (0,3-0,5 mg/l) is the chlorine’s need of waterchlorine’s need of water
Methods of ChlorinationMethods of Chlorination
a.a. By means of chlorine gasBy means of chlorine gasIt is of first choice because it is cheap, quick It is of first choice because it is cheap, quick in action, efficient and easy to apply. in action, efficient and easy to apply. Chlorinating equipment is required to apply Chlorinating equipment is required to apply chlorine gas to water as chlorine gas is irritant chlorine gas to water as chlorine gas is irritant to eyes.to eyes.
b.b. By means of Chloramine:By means of Chloramine:Chloramines are loose compounds of chlorine Chloramines are loose compounds of chlorine and ammonia. They have slower action than and ammonia. They have slower action than chlorine. They give more persistent type of chlorine. They give more persistent type of residual chlorine. They have a less tendency residual chlorine. They have a less tendency to produce chlorinous taste.to produce chlorinous taste.
Chlorine Demand It is the difference between the amount of chlorine added to the water and the amount of residual chlorine remaining at the end of a specific period of contact (1 hour) at a given temperature and pH of water.
Residual Chlorine: Amount of untreated chlorine, remaining in the water after some time as an effective disinfecting agent i.e. 0.3 – 0.5 mg/liter Break point chlorination:The point at which the chlorine demand of water is met and if further chlorine is added free chlorine begin to appear in water Super Chlorination:It is addition of large doses of chlorine to the water and removal of excess of chlorine after disinfection.
Coagulation: Alum and other chemicals are added to water to form tiny sticky particles called "floc" which attract the dirt particles.
How is water treated?
Sedimentation: The heavy particles (floc) settle to the bottom
and clear water moves to filtration.
Filtration: The water passes through filters that help to remove smaller particles.
Disinfection: A small amount of chlorine is added to kill any bacteria or microorganisms that may be in the water.
Storage: Water is placed in a closed tank or reservoir where it flows through pipes to homes and businesses in the community.
Asaka Water Purification Plant
Ozone has been used in water treatment since 1903. It is more Ozone has been used in water treatment since 1903. It is more effective against bacteria and viruses than chlorine and adds no effective against bacteria and viruses than chlorine and adds no chemicals to the water. Ozone cannot be stored and requires an chemicals to the water. Ozone cannot be stored and requires an on-site ozone generator. In general, ozonation equipment and on-site ozone generator. In general, ozonation equipment and operating costs are higher than other treatment proceduresoperating costs are higher than other treatment procedures
Agents alternative to ChlorinationAgents alternative to Chlorination
The ozonization of waterThe ozonization of water Ozone Ozone contains three oxygen atomscontains three oxygen atoms. It is destroyed . It is destroyed
in water, forming atomic oxygen: O3 → O2 → O. in water, forming atomic oxygen: O3 → O2 → O. ozonization is one of the best methods of disinfection: ozonization is one of the best methods of disinfection: water is well disinfected, organic admixtures become water is well disinfected, organic admixtures become destroyed, organoleptic features are improved. Water destroyed, organoleptic features are improved. Water becomes blue and it is equated with spring water.becomes blue and it is equated with spring water.
Ozone dose is 0,5 - 6 mg/l. Sometimes, higher Ozone dose is 0,5 - 6 mg/l. Sometimes, higher doses are necessary for the lighting of water and doses are necessary for the lighting of water and improving other organoleptic features. The time of improving other organoleptic features. The time of disinfection is 3-5 min. The remaining ozone should make disinfection is 3-5 min. The remaining ozone should make up 0,1 – 0,3 mg/l. The concentration of the remaining ozone up 0,1 – 0,3 mg/l. The concentration of the remaining ozone 0.4 mg/l provides the reliable inactivation of 99 % viruses 0.4 mg/l provides the reliable inactivation of 99 % viruses for 5 min.for 5 min.
Advanced Water Purification System
Ultraviolet LightUltraviolet Light Ultraviolet irradiation will kill bacteria by creating Ultraviolet irradiation will kill bacteria by creating photochemical changes in its DNA. No chemicals are added to photochemical changes in its DNA. No chemicals are added to the water by this process. Most ultraviolet water treatment the water by this process. Most ultraviolet water treatment units consist of one or more ultraviolet lamps usually units consist of one or more ultraviolet lamps usually enclosed in a quartz sleeve, around which the water flows. enclosed in a quartz sleeve, around which the water flows. The UV lamps are similar to fluorescent lamps and the quartz The UV lamps are similar to fluorescent lamps and the quartz sleeve surrounding each lamp protects the lamp from the sleeve surrounding each lamp protects the lamp from the cooling action of water. The killing effect of the lamp is cooling action of water. The killing effect of the lamp is reduced when the lamp temperature is lowered. Ground reduced when the lamp temperature is lowered. Ground water is usually a constant temperature year round and so it water is usually a constant temperature year round and so it is possible to set a flow rate that will not lead to excess is possible to set a flow rate that will not lead to excess cooling. cooling.
The effectiveness of UV irradiation depends onThe effectiveness of UV irradiation depends on• the intensity of the light, the intensity of the light, • depth of exposure and depth of exposure and • contact time. contact time.
Water passes in a relatively thin layer around Water passes in a relatively thin layer around the lamp; therefore, water flow must be regulated to the lamp; therefore, water flow must be regulated to ensure that all organisms receive adequate exposure. ensure that all organisms receive adequate exposure. If the water is at all turbid, or if it contains traces of If the water is at all turbid, or if it contains traces of iron, the effectiveness of UV is greatly reduced. In iron, the effectiveness of UV is greatly reduced. In such cases, the water needs to be filtered before it such cases, the water needs to be filtered before it reaches the UV system. reaches the UV system. The maximal bactericidal effect is achieved by the The maximal bactericidal effect is achieved by the waves 250-260 nm, which pass even through the 25 waves 250-260 nm, which pass even through the 25 cm layer of transparent and decolorized water.cm layer of transparent and decolorized water.
The disinfection proceeds very quickly: The disinfection proceeds very quickly: vegetative forms of microorganisms die in 1-2 min. vegetative forms of microorganisms die in 1-2 min. The turbidity, colour and iron salts decelerate the The turbidity, colour and iron salts decelerate the disinfection, decreasing the transparence of water. disinfection, decreasing the transparence of water. Consequently, it is necessary to light and decolorize Consequently, it is necessary to light and decolorize water beforewater before the disinfection.the disinfection.
There are some advantages of UV-There are some advantages of UV-irradiation over the chlorination:irradiation over the chlorination:
bactericidal rays don't denaturate the bactericidal rays don't denaturate the water and don't change its organoleptic water and don't change its organoleptic features, features,
they have wider biological action.they have wider biological action. Their bactericidal action is spread over the Their bactericidal action is spread over the
spores, viruses and worm eggs, resistant to spores, viruses and worm eggs, resistant to chlorine. chlorine.
Many investigators consider this Many investigators consider this method the best for the disinfection.method the best for the disinfection.
PURIFICATION OF WATER ON SMALL SCALEPURIFICATION OF WATER ON SMALL SCALE•House hold purification of waterHouse hold purification of water•Disinfection of wellsDisinfection of wells
• HOUSE HOLD PURIFICATIONHOUSE HOLD PURIFICATIONa.a. By Boiling:By Boiling:Water should be boiled for 5 -10 minutes.Water should be boiled for 5 -10 minutes.It kills all bacteria, spores, cysts & ova.It kills all bacteria, spores, cysts & ova.It removes temporary hardnessIt removes temporary hardnessTaste is altered but is harmlessTaste is altered but is harmless
b.b. Chemical disinfectionChemical disinfectioni) Bleaching Powder (CaOCIi) Bleaching Powder (CaOCI22))Bleaching powder is a white amorphous powder.Bleaching powder is a white amorphous powder.Produced by action of chlorine on slaked lime.Produced by action of chlorine on slaked lime.When freshly made contains 33 % of available When freshly made contains 33 % of available chlorine.chlorine.It must be stored at dark, cool, dry place in a It must be stored at dark, cool, dry place in a closed container that is resistant to corrosion.closed container that is resistant to corrosion.In practise one cup (250 g) of laundry bleach is In practise one cup (250 g) of laundry bleach is mixed with three cups (750 ml) of water to make mixed with three cups (750 ml) of water to make a litre. Three drops of this solution are added to a litre. Three drops of this solution are added to 1 litre water for disinfection. Contact period is 1 litre water for disinfection. Contact period is 30 minutes to 60 minutes. 30 minutes to 60 minutes.
ii.) Chlorine SolutionChlorine solution may be prepared from bleaching powder.* If 4 kg of bleaching powder with 25 % available chlorine is mixed with 20 litres of water, it will give a 5% solution of chlorine.* This solution should be kept in dark, cool and dry place in closed container
v. Potassium Permanganate.It is a powerful oxidizing agent but not recommended as it alters colours, smell and taste of water.
iii. Chlorine tabletsAvailable under different trade name e.g. HalazoneOne tablet of 0.5 g is sufficient to disinfect 20 litres of water. Used in camps and during travel.
iv. Iodine:Two drops of 2 % ethanol solution of iodine is used. A contact period of 20 - 30 minute is sufficient for 1 litre water.
DUAL CHLORINE TABLET CHAMBER UNIT — CAN HOLD UP TO 50 TABLETS
Doulton water filters have a unique 3-stage filtration system. The first stage is the Ceramic filter. This provides a physical barrier that traps and reduces parasites, particulates, turbidity, rust, and dirt greater than 0.9 microns in size. The second stage is High Density Activated Carbon, which reduces chlorine, bad taste and odor. The third stage is a Heavy Metal removing compound that reduces lead.
C. By Filtration Water can be filtered and is purified. Different filters are.
DISINFECTION OF DISINFECTION OF WELLWELL
Wells are main source Wells are main source of water in rural area. of water in rural area. The most effective The most effective and cheapest method and cheapest method of disinfecting wells of disinfecting wells is by bleaching is by bleaching powder. Disinfection powder. Disinfection of well is required in of well is required in normal days and normal days and during epidemics.during epidemics.
Steps:Steps:
1.1. Find volume of water in well.Find volume of water in well.Measure depth of water column — (h) Measure depth of water column — (h) metresmetresMeasure the diameter of well— (d) Measure the diameter of well— (d) metresmetresSubstitute (h) & (d) in:Substitute (h) & (d) in:
Volume (litres) = Volume (litres) = π x dπ x d22 x h x 1000 x h x 1000 π = 3.14 π = 3.14 44
One cubic metre - 1,000 litres of waterOne cubic metre - 1,000 litres of water
2.2. Find amount of bleaching Find amount of bleaching powder requiredpowder required
Measures by Horrock's apparatus.Measures by Horrock's apparatus.Roughly 2.5 gm of good quality Roughly 2.5 gm of good quality
bleaching powder would be required bleaching powder would be required to disinfect 1,000 litres of water.to disinfect 1,000 litres of water.
3. Dissolve bleaching powder in water3. Dissolve bleaching powder in waterThe calculated amount of bleaching powder is placed in a The calculated amount of bleaching powder is placed in a
bucket (not more than 100 g in one bucket) and made into a thin bucket (not more than 100 g in one bucket) and made into a thin paste. More water added till bucket is 3/4 full. The contents are paste. More water added till bucket is 3/4 full. The contents are stirred and allowed to stand for 5 - 10 minutes. When lime settles stirred and allowed to stand for 5 - 10 minutes. When lime settles down, the supernatant solution which is chlorine solution is down, the supernatant solution which is chlorine solution is transferred to another bucket.transferred to another bucket.
4. Delivery of Chlorine solution into the well.4. Delivery of Chlorine solution into the well.The bucket containing the supernatant chlorine solution is The bucket containing the supernatant chlorine solution is
lowered some distance below surface water. The well water is lowered some distance below surface water. The well water is agitated by moving the bucket violently both vertically and agitated by moving the bucket violently both vertically and laterally. Note: The precipitate or lime is never entered in well laterally. Note: The precipitate or lime is never entered in well because it increases the hardness of water.because it increases the hardness of water.
5. Contact period -5. Contact period - 1 hour contact period is required. 1 hour contact period is required.6. Ortho-Tolidine test:6. Ortho-Tolidine test: It is done to list for residual chlorine at the It is done to list for residual chlorine at the
end of one hour. If "free" residual chlorine level is less than 0.5 end of one hour. If "free" residual chlorine level is less than 0.5 mg/ litre, then procedure should be repeated, before water is mg/ litre, then procedure should be repeated, before water is drawn.drawn.
EXPRESS METHODS OF WATER QUALITY EXPRESS METHODS OF WATER QUALITY IMPROVINGIMPROVING
Deodorization Deodorization - - elimination of smack and odour of water elimination of smack and odour of water by aeration, usage of oxidants (ozonization, dioxide of by aeration, usage of oxidants (ozonization, dioxide of chlorine, large doses of chlorine, potassium chlorine, large doses of chlorine, potassium permanganate), filtrating through a layer of absorbent permanganate), filtrating through a layer of absorbent coal, by introduction in water to sedimentation of coal, by introduction in water to sedimentation of absorbent coal.absorbent coal.
Deironation Deironation is carried out by spraying water with the is carried out by spraying water with the purpose of aeration in graduation towers. Thus, bivalent purpose of aeration in graduation towers. Thus, bivalent iron is oxydated in ferric hydroxide, which sediments in iron is oxydated in ferric hydroxide, which sediments in settling tank, or delays on the filter. settling tank, or delays on the filter.
Softening or Removal of hardnessSoftening or Removal of hardnessI.Temporary HardnessI.Temporary Hardness
a.a. BoilingBoilingb.b. Addition of limeAddition of limec.c. Addition of sodium carbonateAddition of sodium carbonated. Permutit processd. Permutit process
II. Permanent HardnessII. Permanent Hardnessa.a. Addition of sodium carbonateAddition of sodium carbonateb.b. Permutit process/ Base exchange process.Permutit process/ Base exchange process.
Boiling:Boiling:It removes temporary hardness by expelling It removes temporary hardness by expelling
carbon dioxide and precipitating the insoluble calcium carbon dioxide and precipitating the insoluble calcium carbonate. carbonate. Ca (HCO3)Ca (HCO3)22→ CaCO→ CaCO33 + CO + CO22 + H + H22OO
Addition of Lime:Addition of Lime:It removes temporary hardness. Lime absorbs It removes temporary hardness. Lime absorbs
carbondioxide and precipitates the insoluble calcium carbondioxide and precipitates the insoluble calcium carbonate.carbonate.Ca (OH)Ca (OH)22 + Ca (HCO + Ca (HCO33))22 →2 CaCO →2 CaCO33 + 2H + 2H22OO
Household water softeners typically use a different process, known as ion exchange.
Ion-exchange devices consist of a bed of plastic (polymer) beads covalently bound to anion groups, such as -COO-. The negative charge of these anions is balanced by Na+ cations attached to them. When water containing Ca2+ and Mg2+ is passed through the ion exchanger, the Ca2+ and Mg2+ ions are more attracted to the anion groups than the Na+ ions. Hence, they replace the Na+ ions on the beads, and so the Na+ ions (which do not form scale) go into the water in their
place.
Addition of Sodium Carbonate,Addition of Sodium Carbonate,It removes both temporary and permanent hardness.It removes both temporary and permanent hardness.
Na2CO3 + Ca (HCO3)2Na2CO3 + Ca (HCO3)2 → 2NaHCO3 + CaCOs→ 2NaHCO3 + CaCOsNa2CO3 + CaSO4 →Na2CO3 + CaSO4 → Na2SO4 + CaCO3Na2SO4 + CaCO3
Base Exchange MethodBase Exchange MethodIn this method sodium permutit is used, which is In this method sodium permutit is used, which is
a combination complex of Na, Al and Si (Naa combination complex of Na, Al and Si (Na22 Al Al22 SiSi22OHOH22O)O)Sodium permutit has property of exchanging the Sodium permutit has property of exchanging the sodium cation for Ca++ and Mg++ ions in water.sodium cation for Ca++ and Mg++ ions in water.NaNa22 Al Si Al Si22O + HO + H22O = Mg++/Ca++O = Mg++/Ca++
When hard water passed, sodium permutit When hard water passed, sodium permutit exchanges Mg/ Ca and is converted into calcium and exchanges Mg/ Ca and is converted into calcium and magnesium permutit.magnesium permutit.
With time permutit loses effectiveness, it is With time permutit loses effectiveness, it is regenerated by adding conc. sol of NaCI.regenerated by adding conc. sol of NaCI.* * By this process hardness of water is removed to By this process hardness of water is removed to zero. As zero hardness is corrosive, therefore a part of zero. As zero hardness is corrosive, therefore a part of raw water is mixed with softened water.raw water is mixed with softened water.
DesaltingDesalting About 97 percent of the water on earth is in the salty oceans. People have found many ways to desalinate, the process for removing salt from seawater and brackish water. The desalination processes used most commonly today are distillation, reverse osmosis, and electrodialysis. These processes produce fresh water from salt water.
This is a water purification plant.
Distillation is the oldest method of turning salt water into fresh water. Seawater can be distilled by simply boiling it in a teapot, and piping the steam into a cool bottle. The salt water turns to vapour under the sun's heat. The vapour rises until it hits the underside of the dome or glass, where it condenses.
Most modern distillation plants use a process Most modern distillation plants use a process called multistage flash called multistage flash distillation.distillation. This is a This is a type of the age-old method of type of the age-old method of boiling and boiling and condensationcondensation. In flash distillation, preheated . In flash distillation, preheated seawater flows into a large chamber in which seawater flows into a large chamber in which the pressure is low. The low pressure causes the pressure is low. The low pressure causes some of the water to instantly turn into steam some of the water to instantly turn into steam The steam is condensed into salt-free water. The steam is condensed into salt-free water. The seawater passes through several The seawater passes through several distillation chambers. Each of the chambers has distillation chambers. Each of the chambers has a lower pressure than the previous chamber. a lower pressure than the previous chamber. Often, the final water is so pure that it is Often, the final water is so pure that it is tasteless, and some salt must be tossed back in tasteless, and some salt must be tossed back in to give it flavour to give it flavour
Reverse osmosisReverse osmosis is a widely used method for is a widely used method for desalting seawater and brackish water. In normal desalting seawater and brackish water. In normal osmosis, a less concentrated liquid flows through a osmosis, a less concentrated liquid flows through a membrane into a more concentrated liquid. Thus, if salt membrane into a more concentrated liquid. Thus, if salt water and fresh water are separated in a chamber by a water and fresh water are separated in a chamber by a special semi-permeable membrane, the fresh water will special semi-permeable membrane, the fresh water will flow through the membrane into the salt water. flow through the membrane into the salt water.
ElectrodialysisElectrodialysis is used chiefly to desalt brackish is used chiefly to desalt brackish ground water and water from estuaries, or river mouths. ground water and water from estuaries, or river mouths. Electrodialysis is based on the fact that when salt is Electrodialysis is based on the fact that when salt is dissolved in water, it breaks up into ions, or electrically dissolved in water, it breaks up into ions, or electrically charged particles, of sodium and chloride. Sodium ions charged particles, of sodium and chloride. Sodium ions carry a positive charge, and chloride ions carry a carry a positive charge, and chloride ions carry a negative chargenegative charge..
Other desalting processes are also being studied. Other desalting processes are also being studied. During the 1970's, several plants experimented with During the 1970's, several plants experimented with freezing freezing as a method of desalination. When seawater as a method of desalination. When seawater freezes, the ice crystals produced are pure water in solid freezes, the ice crystals produced are pure water in solid form. The salt is separated and trapped between the ice form. The salt is separated and trapped between the ice crystals.crystals.
FluoridationFluoridation is addition of fluoride to public water is addition of fluoride to public water supplies to reduce tooth decay. supplies to reduce tooth decay. Fluoride is a compound consisting of the element fluorine Fluoride is a compound consisting of the element fluorine and a metallic element such as and a metallic element such as sodiumsodium (forming sodium (forming sodium fluoride, used in water supplies) or fluoride, used in water supplies) or tin tin (forming stannous (forming stannous fluoride, used in toothpaste). fluoride, used in toothpaste). Water fluoridation has been recognized as a significant Water fluoridation has been recognized as a significant method in preventing tooth decay since the 1930s.method in preventing tooth decay since the 1930s.The maximum protection by fluoridation against tooth The maximum protection by fluoridation against tooth decay occurs when children consume fluoridated water decay occurs when children consume fluoridated water from birth through age 13. from birth through age 13. 0,7-1,5 mg/dm0,7-1,5 mg/dm33 of fluoride is the optimal concentration of of fluoride is the optimal concentration of fluoride in water. fluoride in water.
Fluorosis (tooth staining) was found to occur at Fluorosis (tooth staining) was found to occur at levels levels more than 1,5 mg/dmmore than 1,5 mg/dm33..
For hygienic purposes the For hygienic purposes the examination of water is examination of water is generally done under the generally done under the following heads:following heads:
1.1. Physical Examination.Physical Examination.
2.2. Chemical Examination.Chemical Examination.
3.3. Microscopical Microscopical Examination.Examination.
4.4. Bacteriological Bacteriological Examination.Examination.
EXAMINATION OF EXAMINATION OF WATERWATER
Before water from any Before water from any source is declared fit for source is declared fit for human consumption, it is human consumption, it is essential to carry out the essential to carry out the following examination.following examination.
Water Quality Inspection Water Quality Inspection Division conducts inspections of Division conducts inspections of water quality from water sources to water quality from water sources to household taps and carries out household taps and carries out surveys and research in order to surveys and research in order to ensure safe drinking water.ensure safe drinking water.
Sampling in water sources
Monitoring and control of water quality To monitor water resources, raw water taken from rivers and lakes is periodically inspected. Moreover, detailed inspections, surveys and research are also conducted with respect to tap water.
Physical, chemical and Physical, chemical and biological examinationbiological examinationMeasuring some metalsMeasuring some metalsand planktons by theand planktons by theelectron microscope. electron microscope.
Physical andPhysical andchemical examinationchemical examinationMeasuring pesticides byMeasuring pesticides byGC/MS(gas chromatograph GC/MS(gas chromatograph mass spectrometer)mass spectrometer)
Water quality inspectionsWater quality inspections
Response to emergenciesResponse to emergencies
Water quality inspection car
Microbiologicalexamination
Tests for coli form groupand standard plate count.
Inside of water qualityinspection car
