Waste-water Composting

Separation Is Key To Composting

• Waste-water treatment plants separate materials that come into their systems. Liquids are separated from solids and large particles from the small ones. The large particles are diverted to landfills, while the small particles are pushed into the system for further treatment, such as composting.

Basic Composting At Treatment Plants

• Many waste-water treatment facilities compost on a basic level, according to Colby College in Waterville, Me. Often called "secondary treatment," smaller particles that have been initially separated are subjected to biological purification, or basic composting. Microorganisms, helped along by a consistent oxygen supply, digest the material, which is mostly organic. This removes up to 99.9 percent of pathogenic bacteria and 90 percent of enteroviruses.

Further Composting

• Some waste-water treatment facilities further compost their solid wastes as a way of dealing with the vast quantities of sewage that enter their systems. Most of the water is removed from the sewage, creating sludge. The sludge is then processed in facilities designed to decompose and hold the waste for an extended period of time.