APES Chapter 17 Water Pollution

cultural eutrophication

over nourishment of aquatic ecosystems with plant nutrients because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants

eutrophication

physical, biological, and chemical changes that take place after a lake, estuary, or slow moving stream receives inputs of plant nutrients-mostly nitrates and phosphates-from natural erosion and runoff from the surrounding land basin

nonpoint sources

broad, and diffuse areas, rather than points, from which pollutants enter bodies of surface water or air.

point sources

single identifiable source that discharges pollutants into the environment

primary sewage treatment

Mechanical sewage treatment in which large solids are filtered out by screens and suspended solids settle out as sludge in a sedimentation tank.

secondary sewage treatment

Second step in most waste treatment systems in which aerobic bacteria decompose as much as 90% of degradable, oxygen-demanding organic wastes in wastewater. It usually involves bringing sewage and bacteria together in trickling filters or in the activated sludge process.

septic tank

a component of a small scale underground sewage treatment system used for homes in rural and suburban areas that do not have connections to municipal sewer lines. Wastewater enters the tank form the home, solids sink to the bottom of the tank, and bacteria begin to decompose the waste before it discharges into a leeching field

wastewater

water containing organic and inorganic wastes from homes, businesses, and industry

water pollution

Any physical or chemical change in surface water or groundwater that can harm living organisms or make water unfit for certain uses.