Question

how should sewage be treated before its discharge into sea /river/lack​

Answer 1

1) it should be sent to swage water plant where all the dirts get removed and then clean water can be treated in river

Answer 2

Wastewater treatment is a process to improve and purify the water, removing some or all of the contaminants, making it fit for ay be to surface water, such as rivers or the ocean, or to groundwater that lies beneath the land surface of the earth.