بسم الله الرحمن الرحيم

PURIFICATION OF WATER PURIFICATION OF WATER It is of great importance for promoting health and preventing disease. It is of great importance for promoting health and preventing disease. Purpose of water treatment, is To produce water that is safe and wholesome. To produce water that is safe and wholesome. Ground water (e.g., wells and springs) may need no treatment, other than disinfection, surface water (e.g., river water) which tends to be turbid and polluted, requires extensive treatment. Ground water (e.g., wells and springs) may need no treatment, other than disinfection, surface water (e.g., river water) which tends to be turbid and polluted, requires extensive treatment. Components of water purification system are Storage, Filtration and Disinfection. Components of water purification system are Storage, Filtration and Disinfection.

Methods of Water Purification Water purification is done on small scale at domestic level and large scale. Water purification is done on small scale at domestic level and large scale. Methods of Purification Methods of Purification Natural methods of purification Natural methods of purification Man –made methods of purification Man –made methods of purification

NATURAL METHODS OF PURIFICATION The natural methods by which water is purified are:- Dilution Dilution Sedimentation Sedimentation Oxidation Oxidation Aeration Aeration Ultraviolet rays Ultraviolet rays Action of Aquatic plants and animals Action of Aquatic plants and animals Action of sunlight Action of sunlight Some measure of disinfection is accomplished by exposure to sun light provided that there is time for biochemical stabilization of organic matter and destruction of microorganisms. Some measure of disinfection is accomplished by exposure to sun light provided that there is time for biochemical stabilization of organic matter and destruction of microorganisms.

Purification on small scale Boiling (5 to 10 minutes kills off most microorganisms and removes temporary hardness) Distillation: By this method get rid of all impurities Chemical Disinfection: Chlorine solution (small quantity of 5% bleaching powder solution is sufficient for chlorination of water) Chlorine tablets ( 1 tablet is required for 1 liter of water) Iodine ( 2 drops of 2% solution of iodine is required for 1 liter of water) Iodine ( 2 drops of 2% solution of iodine is required for 1 liter of water) Potassium permanganate (a little amount giving pink coloration) Potassium permanganate (a little amount giving pink coloration) Alum (.1 to.4 gram is required for 5 liters of water) Three pot domestic filtration:

FILTERATION Filtration systems are of two types SLOW SAND OR BIOLOGICAL FILTERS SLOW SAND OR BIOLOGICAL FILTERS Elements of a slow sand filter Elements of a slow sand filter Essentially these consist of, supernatant (raw) water, a bed of graded sand, an under – drainage system; and a system of filter control valves Essentially these consist of, supernatant (raw) water, a bed of graded sand, an under – drainage system; and a system of filter control valves Supernatant water1 to 1.5 meter Sand bed1.2 meters Sand bed1.2 meters Gravel support0.3. Meter Gravel support0.3. Meter Filter bottom0.16 meter Filter bottom0.16 meter Vital Layer It develops in first few days and consists of threadlike algae. It removes organic matter and holds back bacteria.

RAPID SAND OR MECHENICAL FILTERS The raw water is first treated with a chemical such as alum, the dose of which varies from 5-40mg or more per liter, depending upon the turbidity, the gentle stirring results in the formation of a thick, flocculent precipitate of AloH. These are removed by sedimentation and rapid sand filters.

SURVEILLANCE OF DRINKING WATER QUALITY Sanitary survey: Sanitary survey: Sanitary survey is an on-the-spot inspection and evaluation by a qualified person of the entire water supply system. The purpose of the survey is detection and correction of faults and deficiencies. A sanitary survey is essential for adequate interpretation of laboratory results. Sanitary survey is an on-the-spot inspection and evaluation by a qualified person of the entire water supply system. The purpose of the survey is detection and correction of faults and deficiencies. A sanitary survey is essential for adequate interpretation of laboratory results. Sampling: Sampling: Sampling of water should be done with the thoroughness of a surgical operation, with the observation of similar aseptic precautions, it depends upon the results of analysis. It should be carried out by competent and trained personnel. Sampling of water should be done with the thoroughness of a surgical operation, with the observation of similar aseptic precautions, it depends upon the results of analysis. It should be carried out by competent and trained personnel. Bacteriological surveillance: Bacteriological surveillance: The tests usually employed in water bacteriology are presumptive coliform test.Tests for the detection of faecal streptococci and Cl. Perfringens is also done. A complete bacteriological examination consists of all these tests. The tests usually employed in water bacteriology are presumptive coliform test.Tests for the detection of faecal streptococci and Cl. Perfringens is also done. A complete bacteriological examination consists of all these tests.

Examination of Water Before water from any source is declared fit for human consumption, it is essential to take the sample and carry out the following examinations. Before water from any source is declared fit for human consumption, it is essential to take the sample and carry out the following examinations. Physical examination Physical examination Chemical examination Chemical examination Bacteriological examination. Bacteriological examination.

Informations required for sampling The following information should be furnished along with the sample of water. The following information should be furnished along with the sample of water. Source of water supply Source of water supply Geological formation of the soil if available Geological formation of the soil if available In case of well, its depth, diameter and how it is used. In case of well, its depth, diameter and how it is used. Any suspected source of pollution in the vicinity. Any suspected source of pollution in the vicinity. Whether any method of purification is used. Whether any method of purification is used.

Sample Collection Sampling from the stream: Water is taken from the middle of a stream. With the mouth of the bottle facing upstream, lower the bottle into the stream and allow to fill. Tilt bottle upwards to fill completely, the cap is carefully screwed back, taking care not to touch the screw thread at the top of the bottle, nor the inside of the cap.

Sampling from a Well Tie a sample bottle on to a weighted length of a rope or strong string. Use a stone or piece of metal weighing about 500g as the weight and attach the bottle just above it. After removing the cap aseptically, lower the bottle into the well to a depth of about 1 m. when no more air bubbles rise to the surface, raise the bottle out of the well and carefully replace the cap.

Sampling from a tap Flame a tap till it is red hot to ensure that it is sterilized, from the inside. Turn the tap full on and allow the water to run to waste for one minute. Close the tap until only a slow trickle of water is coming out and fill the sampling bottle. Carefully replace cap. Flame a tap till it is red hot to ensure that it is sterilized, from the inside. Turn the tap full on and allow the water to run to waste for one minute. Close the tap until only a slow trickle of water is coming out and fill the sampling bottle. Carefully replace cap.

Water Quality – Criteria and Standard The guideline for drinking water quality recommended by WHO (1993 and 1996) relate to following variables: The guideline for drinking water quality recommended by WHO (1993 and 1996) relate to following variables: Acceptability aspects Acceptability aspects Microbiological aspects Microbiological aspects Chemical aspects Chemical aspects Radiological aspects Radiological aspects

Acceptability Aspects Physical Constituents or characteristics Acceptability Aspects Physical parameters Colour Colour Taste and odour Taste and odour Temperature Temperature Turbidity TurbidityAppearance Should be acceptable No turbidity

Acceptability Aspects Chemical Inorganic constituents Effects Aluminium Aluminium Ammonia Ammonia Chloride Chloride Copper, Iron, Manganese Copper, Iron, Manganese Hardness Hardness Hydrogen sulfide Hydrogen sulfide Dissolved oxygen Dissolved oxygen pH value pH value Sodium Sodium sulfate sulfate Total dissolved solids Total dissolved solids Zinc Zinc Depositions, discoloration Odour and taste Taste, corrosion Staining of laundry and sanitary ware High hardness: scale deposition, scum formation; low hardness; possible corrosion odour and taste Odour and taste Guideline value 0.5 mg/L. Low pH: corrosion; high pH: taste, soapy feel preferable < 8.0 for effective disinfection with chlorine Taste Taste, corrosion Taste Appearance, taste

Microbiological Aspects Organisms Guideline value All water intended for drinking E.coli or thermo tolerant coli form bacteria Treated water entering the distribution system E.coli or thermo tolerant coli form bacteria Total coli form bacteria Treated water entering the distribution system E.coli or thermo tolerant coli form bacteria Total coli form bacteria Must not be detectable in any 100 ml sample sample. In the case of large supplies, where sufficient samples are examined, must not be present in 95% of samples taken throughout any 12-month period.

CHEMICAL ASPECTS Iodine deficiency Goiter Excess Fluoride Dental flourosis Fluoride deficiency Dental caries Excess inorganic salt Diarrhea Cadmium Gastric upsets SodiumHypertension Sulfates Laxative effect Nitrates and nitrites Methaemoglobinaemia

Typical Non infectious diseases associated with water supply (Heavy Metals) Lead Lead poisoning Arsenic Black foot disease Arsenic Skin and lung cancer Cadmium Itai-itai disease CadmiumNephropathia Mercury Minimata disease MercuryNephropathia

Radiological Aspects There are two types: There are two types: 1. Somatic effects Any exposed individual manifest the radiological effects these are called somatic effects e.g., development of carcinomas. 2. Hereditary effects: The pregnant ladies manifest the radiological effects in the growing fetus in the form of hereditary changes.