Sewage is composed of a total of 90% water and 1% solid wastes. In addition, it also includes various microbes like Colliforms, Streptococci, Clostridia, Lactobacilli, Mincrofungi, Protozoans and micro algae. Such microbes do the natural treatment of sewage.
Hazards of Sewage: The proper placement of sewage has the primary importance. It sewage is treated in river, it has many fateful consequences, as such.
(a) Many water born diseases occur due to infection of such microbes.
(b) Due to this there is deficiency of dissolved oxygen. Due to such oxygen deficiency, many aerial aquatic microbes die.
