Chapter 2 - Water Pollution

Abstract

The increasing complexity of chemical pollution is evolutionary. In response to the increase and complexity of both human and industrial pollution, methods for treating pollution have also evolved. Primarily because of cost, however, advanced treatment technologies have got implemented only selectively and nonpoint sources of pollution remain virtually uncontrolled. Because of the biological and chemical diversity and complexity of today's pollution, the environment simply cannot assimilate all these potentially harmful discharges. Furthermore, pollution regulations around the world allow chemical pollution of water resources as long as ambient water quality criteria are not exceeded. Thus, pollution of the water resources has become unavoidable. Human wastes and industrial pollutants are the major culprits. The combination of municipal sewage and industrial waste discharges coupled with an expanding economy required that pollutant waste loads be reduced. Steps were taken to ensure that solid wastes were not to be dumped into surface waters and that wastewater was treated to remove some fraction of its chemical and biological constituents before its discharge to surface waters. These actions gave rise to the development of centralized sewage and industrial treatment facilities. The state regulations limited the amount of chemicals and bacteria in sewage and industrial waste discharges so as to reduce the pollution load on receiving waters. Greater emphasis was also placed on "engineered" waste treatment prior to waste discharge to the environment. On a community-wide basis, this emphasis led to the development of publicly owned treatment works (POTW) that contained the following primary treatment processes.