Sewage Treatment

The objective of sewage treatment is basically to satisfy the biochemical oxygen demand (BOD) as well as chemical oxygen demand (COD) of wastewater. It is important to satisfy these demands to safeguard the biological life downstream. When the treated streams join natural water stream or bodies, one has to ensure that it should not deplete oxygen available in those streams, else all biological life will be in dander.
Conventional treatment comprises of aeration that satisfies both BOD and COD demands. The typical treatment regime comprises of oxidation, nitrification followed by denitrification steps. Packaged treatment plants make use of either fixed or floating plastic media to facilitate attached growth of bacteria. This reduces the size of the plant. Also smell reduction can be a achieved in packaged plants.