Treatment of water for drinking purpose

Water is the elixir of life & Major area of earth surface covered by water
Water is the elixir of life & Major area of earth surface covered by water

1. Treatment of water for drinking purpose M.SRIDEVI II M.SC MICROBIOLOGY 18PY15

2. Introduction Water is the elixir of life & Major area of earth surface covered by water Water free from harmful chemicals & disease causing microorganism is known as potable water Water is polluted by industrial, municipal & commercial activities that release toxic and recalcitrant compound in water effluents

3. Microorganism in domestic water Bacteria serratia Streptococcus faecalis shigella Streptococcus bovis klebsiella proteus E.coli Salmonella pseudomonas

4. Virus Polio virus Protozoan Entamoeba histolytica Giardia Fungi Achlya Americana Pythium Saprolegnia Algae Nostoc & anabaena spirulina

5. Water treatment Primary treatment Coagulation Flocculation Sedimentation Secondary treatment Filtration Tertiary treatment Disinfection

6. Primary treatment Coagulation Coagulant make the small physical particles in the water clump together (coagulation ). It is used for removal of solids in suspension Coagulants: aluminium sulphate, polyaluminum chloride Negative charge on the particles are neutralized by inorganic coagulants.

7. 2. Flocculation The precipitates in the water combine into large particles under natural processes such as Brownian motion & induced mixing is referred as flocculation Thicker, denser ‘floc’ floats down and settles out of the water in large tanks (sedimentation) or is removed during the next stage, filtration

8. 3. sedimentation Sedimentation is done when water consists of large sized organic materials . Suspended particles settle down depending on their size & weight and condition of the stored water Rate of sedimentation is enhanced by adding coagulants The suspended materials & microorganism entrapped by coagulants and settle down rapidly

9. Fig: sedimentation tank Water exiting the flocculation basin may enter the sedimentation tank It is a large tank with low water velocities, allowing floc to settle to the bottom

10. Fig: coagulation

11. Secondary treatment In the secondary treatment , the soluble waste are removed from the water coming out from the primary treatment It helps to Stabilize organic matter Remove odor Reduce BOD& COD Remove non-sedimentable colloidal particle

12. Secondary treatment Filtration It is the second step of purification After sedimentation the water is further purified by passing to filtration unit It is the effective means of removing the microorganism & the other suspended material There are two type of sand filter, such as Slow sand filter Rapid sand f ilter

13. Slow sand filter Rate of filtration is slow Water passes solely through the filter & collected by tile drain pipes at the bottom In the surface of layer of fine sand a colloidal material, consisting of bacteria, algae, & protozoa, is attached Sand grains have positive charges and bacterial cell walls have negative charge Therefore, bacteria are adsorbed on the surface of sand Protozoa ingest bacteria

14. Rapid sand filter This method depend on the physical trapping of fine particles and coagulants. The top layer removes organic compound About 99% bacteria are removed by this method But does not remove giardia lamblia cysts, cryptosporidium oocysts, cyclospora & viruses It is 50 time faster than sloe sand filter

15. Fig: sand filte r

16. Tertiary treatment I t is the final treatment of water It remove inorganic nutrients, virus & trace elements from the effluent Tertiary treatment removes The fine suspended solids Bacteria Dissolved inorganic solids

17. Chemical treatment Chlorination Most common disinfection method involves some form of chlorine or its compounds such as chloramine or chlorine dioxide Chlorine is a strong oxidant that rapidly kills many harmful micro organism The amount of chlorine required depends on organic matter & number of microorganism present in the water Chlorine fail to kill microbial spores

18. Fig: chlorination

19. 2.ozone disinfection Powerful oxidizing agent which is toxic to most waterborne organisms It is an effective method for inactive harmful protozoa that form cysts 3. Neutralization Mainly used in industrial water treatment Addition of acid or base to adjust pH level Calcium hydroxide is used in neutralization of acid wastes

20. Thank you