Sewage treatment covers any artificial process to which sewage is subjected in order to remove or alter its objectionable constituents so as to render it less dangerous or offensive. Sewage before being disposed of either in river, land or other places has generally to be treated to make it safe both for environment and living beings. Following points can direct us to the need for sewage treatment:
- Sewage is both dangerous to health and a potential nuisance
- Raw or untreated sewage discharged into the stream forms objectionable deposits on the bed
- Grease and soap contained in the sewage will rise to the surface of the stream and from a scum
- Fish may be killed and stream may be spoiled from any recreational use
- Disease bearing bacteria may be carried in the bodies of the cows that wade in contaminated stream, those bacteria may reach the milk during the process of milking
- Sewage may contain bacteria that cause typhoid, fever, various forms of dysentery and cholera.