Sewage is liquid waste from households and retail areas that contains sanitary waste (Feces and urine), soaps, food scraps, water, cooking wastes etc. It is gathered and pip…ed to sewage treatment plants. Depending on the complexity of the plant the treatment consists of: .
Primary treatment: "De-lumping" the sewage and allowing the fluids to sit in lagoons for a period of time before discharge. Removed solids are disposed of to land. .
Secondary Treatment: "Delumping" the sewage. Allowing the sewage to be mixed with bacteria in aeration basins which remove the dissolved organics. Removing the bacteria and discharging the treated water. Removed solids are disposed of to the land or anaerobically digested to generate methane. .
Tertiary Treatment: The same as Secondary Treatment but the effluent is filtered and disinfected before discharge .
Storm water can also be considered as sewage. In many cases it has as many contaminants as sanitary sewage. I is generally simply settled prior to discharge to allow solids to settle out and oils to float to the top for removal. (MORE)