Aerobic Based Water Treatment:
Waste water provides organic materials and inorganic nutrients to river waters; this is known as eutrophication. This promotes microbial and plant growth which reduces oxygen from the water resulting in death of fish and other types of fauna. Sometimes algal and plant growth can be so profuse as to physically block the river. Waste waters can also add inert particulate matter which settles in the bottom of the river; sometimes it may be hot and increase the river water temperatures. All these factors affect the composition and the population of flora and fauna of the rivers.