The effluent flows out of the tank into the ground through drains. The sludge is pumped out of the tanks, usually by commercial firms, at regular intervals. Sewers are a system of pipes that collect and deliver waste water to treatment plants or receiving streams. Sludge is the solid matter that settles to the bottom, floats, or becomes suspended in the sedimentation tanks and must be disposed of by filtration and incineration or by transport to appropriate disposal sites. Storm Sewers are a separate system of pipes that carry only runoffs from buildings and land during a storm.
Sterilization is the destruction of all living organisms.
In contrast, disinfection is the destruction of most of the living organisms. Suspended Solids are the small particles of solid pollutants which are present in sewage and which resist separation from the water by conventional means. Trickling Filter is a support media for bacterial growth, usually a bed of rocks or stones. The sewage is trickled over the bed so the bacteria can break down the organic wastes. The bacteria collect on the stones through repeated use of the filter.