1. What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
Domestic sewage refers to the wastewater coming from toilets, kitchen and washings which is passed into sewer systems. Domestic sewage contains fibrous matter, grit, colloidal particles, faecal matter, small sized food leftovers, pathogens, nitrates, phosphates and other salts etc.
The effects of sewage discharge on a river
1. Sewage discharge causes a rise in BOD or biological oxygen demand thus reducing the amount of dissolved oxygen in the river
2. Sewage discharge causes the disappearance of fishes and some other aquatic animals in the river
3. Water becomes turbid, odorous and unfit for human drinking