Sewage Definition

Sewage water is generated from domestic, factories and agricultural activities. Domestic waste water is called as sewage

Sources of sewage

• waste water from kitchen and bathroom is called gray-water or sullage

• waste water from toilet is called excreta or black- water

Sewage water consists of 99.3 to 99.7 % of liquid state and 0.3 to 0.7% of solids state.

The solids present in the sewage water are of two types

1. Organic solids
2. Inorganic solids.

Organic solids are the substances derived from living things like produces from plant and animal. The organic solids undergo decomposition by the microorganisms.

Examples : carbohydrate, protein & fat.

Inorganic solids are inert materials that they do not undergo decomposition by the microorganisms and are inert fixed solids.

Examples: Grit, Salt, Chemicals, Metals etc.

These two states are mainly degradation of the environment if they are discharged into the environment as such.

If these solids are removed  from the sewage water by Treatment process the water can be reclaimed and reused.

Composition of Sewage