Question : Whatare thevariousconstituents of domesticsewage ? Discuss the effects sewagedischargeon a river .

Question : Whatare thevariousconstituents of domesticsewage ? Discuss

1.	Question : Whatare thevariousconstituents of domesticsewage ? Discuss the effects sewagedischargeon a river .
Answer» Solution :Domesticsewageincludes biodegradable pollutantssuch as ANIMALSAND human excreta , dissolvedorganic compounds , nitrateand phosphates , sodium , potassium, c alcium and chlorideions . Usually these pollutants undergo rapid decomposition ,but sometimetheyaccumulatein largerquantities in the fieldand cause problems . The sewagemay alsopercolatethrough the soiland reachthe WATER tableand contaminate the drinkingwater. Besides, the sewagekills the living fishand other aquaticanimals and reduces the oxygencontentof the water and causes excessive GROWTHOF microorganisms(algal bloom) adaquatic VEGETATION . This process is know as eutrophication . Undersuch conditions , oxygen content is very low andthe riverwaterbecomes foul smellingdue to putrifactionand the river becomes degraded. Due tohigh growth of micro-organisms, thebiological oxygen demand (BOD) of thewater increases. BOD is a testof the amountof oxygenneeded for bacteriato breakdown theorganicmatterin a water sample a period of FICE days.