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Flashcards in WASTE WATER STORY Deck (10)
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What is sewage?

sewage is the waste water released by homes, offices, and industries along with the rain water that runs down the street after a heavy rain


what are the types of sewage?

sullage water that comes out from the kitchen
foul waste that comes out of the toilets
trade waste that comes out from the industries and factories


what are contaminants?

contaminants are the suspended impurities present in the sewage


name 2 organic impurities present in the contaminants?

animal waste and oil


name 2 inorganic impurities present in the contaminants

phosphates and nitrates


name 2 nutrients present in the contaminants

phosphorus and nitrogen


why untreated sewage should not be discharged into rivers or seas?

this can pollute natural sources of water. it also contains harmful disease causing organisms


write the function of manholes in a sewage system

manholes are used for timely inspection of the sewers and for repair work in case of any blockage


what is a waste water treatment plant?

these are large plants which remove all the impurities from the water before it can be used or sent in the water bodies


explain the physical, chemical and biological processes of the waste water treatment plant

Physical process
Bar Screening- the waste water is passed through the bar screen. this separates the large impurities like plastic bottles from the water
Grid and Sand Remover- the waste water is slowly passed through the sedimentation tanks. grid, sand and pebbles settle down in this process.
Sedimentation- water is then sent into the sedimentation tanks in this the water speed is decreased so that the solids like faecel settle at the bottom while the floatable impurities such as oil and greece float. the ice scrapper removes the impurities at the bottom. the skimmer removes the floatable impurities. now the water is clarified

Biological process
Aeration- air is pumped into clarified water so that the aerobic bacteria can consume human waste and leave food waste, soaps and unwanted materials. these microbes settle down at the bottom and after several hours the water is removed from the top. this water is fit for irrigation.

Chemical process
Chlorination- water purified through irrigation is not fit for drinking so this water must be treated with chlorination which needs bleaching to be done chlorine removes all the germs in the water. now the water is fit for drinking.