بسم الله الرحمن الرحيم

1. بسم الله الرحمن الرحيم

2. PURIFICATION OF WATER • It is of great importance for promoting health and preventing disease. Purpose of water treatment, is • 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. • Components of water purification system are Storage, Filtration and Disinfection.

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

4. NATURAL METHODS OF PURIFICATION The natural methods by which water is purified are:- • Dilution • Sedimentation • Oxidation • Aeration • Ultraviolet rays • Action of Aquatic plants and animals • 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.

5. 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) Potassium permanganate (a little amount giving pink coloration) Alum ( .1 to .4 gram is required for 5 liters of water) Three pot domestic filtration:

6. FILTERATION Filtration systems are of two types • SLOW SAND OR BIOLOGICAL FILTERS • 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 Supernatant water 1 to 1.5 meter • Sand bed 1.2 meters • Gravel support 0.3. Meter • Filter bottom 0.16 meter Vital Layer It develops in first few days and consists of threadlike algae. It removes organic matter and holds back bacteria.

7. 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.

8. SURVEILLANCE OF DRINKING WATER QUALITY • 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. • 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. • 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.

9. 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. • Physical examination • Chemical examination • Bacteriological examination.

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

11. 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.

12. 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.

13. 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.

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

15. Acceptability AspectsPhysical

16. Acceptability AspectsChemical

17. Microbiological Aspects

18. CHEMICAL ASPECTS

19. Typical Non infectious diseases associated with water supply (Heavy Metals)

20. Radiological Aspects There are two types: • 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.