ABSTRACT
Much of the waste of civilization enters water bodies through the discharge of water-borne wastes, termed wastewater. That is, the water used by the urban population for drinking/washing or by industry for cooling/washing/ processing is discharged carrying the unwanted and unrecovered substances. Wastewater can be treated or untreated and has conventionally referred primarily to that which enters water bodies at points of concentrated flow (through pipes), or point sources. Point sources include wastewater effluent from municipal and industrial sources. Although flow and pollutant loads can vary, this variability is not directly related to meteorological conditions (Novotny and Olem, 1994). Pollutants from diffuse or non-point sources enter water bodies in a diffuse manner at intermittent intervals that are generally related to meteorological events (e.g. precipitation). Diffuse sources are more difficult to monitor and to treat. Examples include urban runoff, agricultural and silvicultural runoff, flow from abandoned mines, and wet and dry atmospheric deposition over a water surface (Novotny and Olem, 1994). Point sources in the USA are regulated under the Clean Water Act of 1972 and the Water Quality Act of 1987 and have been, for the most part, effectively controlled through waste treatment processes. However, non-point sources remain a largely uncontrolled source of pollutants to surface waters.
