Question

What is the secondary treatment of sewage water?

Answer 1

Secondary treatment is a wastewater treatment process that uses a sewage treatment plant with physical phase separation to remove settleable solids and a biological process to remove dissolved and suspended organic compounds to achieve a certain level of effluent quality (for example, sewage but also some types of industrial wastewaters). The wastewater may be referred to as secondary-treated wastewater after this type of treatment.

Complete answer:
The component of a sewage treatment sequence that removes dissolved and colloidal chemicals, evaluated as biochemical oxygen demand, is known as secondary treatment (BOD). After initial treatment has removed settleable solids and floating material, secondary treatment is traditionally conducted to the liquid portion of sewage. Microorganisms in a controlled aerobic habitat frequently undertake secondary treatment (however, it can also be an anaerobic process). While reproducing to build cells of biological solids, bacteria and protozoa ingest biodegradable soluble organic pollutants (e.g. sugars, fats, and organic short-chain carbon molecules from human waste, food waste, detergents, and detergent).
Secondary treatment of dissolved and colloidal organic molecules by biochemical oxidation is commonly employed in sewage treatment and can be applied to some agricultural and industrial wastewaters.
Secondary treatment is used to significantly reduce the biological component of sewage, which includes human waste, food waste, soaps, and detergents. As a secondary treatment stage, the majority of municipal plants use aerobic biological processes. The biota requires both oxygen and food to function properly. Biodegradable soluble organic pollutants (e.g. sugars, lipids, organic short-chain carbon molecules) are consumed by bacteria and protozoa, which bind much of the less soluble fractions into floc.

Note:-
Separation of floating debris and heavy solids from liquid waste is possible with primary sewage treatment using quiescent settling. The leftover liquid usually contains less than half of the original solids and two-thirds of the BOD in colloids and dissolved organic molecules. Primary processed sewage may be dumped where surrounding water bodies can quickly dilute this liquid waste, allowing natural biological decomposition to oxidise any remaining waste.