Water Pollution and its Prevention

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Chapter 17: Water Pollution and its Prevention
·The Mississippi River encompasses 40% of the land area of US ·Lack of oxygen is deadly to bottom dwelling animals
·Nitrogen is a common limiting factor in coastal marine waters 17.1 Water Pollution
·Any material that causes pollution is called a pollutant
I.Pollution Essential
·Pollutants are almost by-products of otherwise essential activities ·. Many materials now widely used are nonbiodegradable
·The general strategy for fighting pollution must be:
1.Identify the material or materials that are causing the pollution 2.Identify the sources of the pollutants
3.Clean up the environment already impacted by pollution
4.Develop and implement pollution control strategies to prevent the pollutants from entering the environment 5.Develop and implement alternative means of meeting the need that do not produce the polluting by product II.Water Pollution: Sources, Types, Criteria

·For purposes of regulation, it is customary to distinguish between point sources and nonpoint sources of pollutants ·Point sources involve the discharge of substances from factories, sewage systems, power plants, coal mines, and oil wells ·Two basic strategies are employed in attempting to bring water pollution under control: 1) reduce or remove the sources and 2) treat the water before it is released so as to remove pollutants or convert them to harmless forms A.Pathogens

·Most serious water pollutants are the infectious agents that cause sickness and death ·Pathogens – disease causing bacteria, viruses and other parasitic organisms ·The following measures were important in controlling waterbourne diseases: 1.Purification and disinfection of public water supplies with chlorine or other agents 2.Sanitary collection and treatment of human and animal wastes 3.Maintenance of sanitary standards in all facilities in which food is processed or prepared for public consumption 4.Instruction in personal and domestic hygiene practices

·Largely because of poor sanitation regarding water and sewage, a significant portion of the world’s population is chronically infected with various pathogens B.Organic Waste
·When bacteria and detritus feeders decompose organic matter in water, they consume oxygen gas dissolved in the water ·Bacteria keep the water depleted in DO as long as there is dead organic matter to support their growth and oxygen replenishment is inadequate ·Biochemical oxygen demand is a measure of the amount of organicmaterial in water, in terms of how much oxygen will be required to break it down biologically, chemically, or both ·If the system goes anaerobic, only bacteria can survive, using their abilities to switch to fermentation or anaerobic respiration C.Chemical Pollutants

·The organic chemicals are another group of substances found in polluted waters ·Many of these pollutants are toxic even at low concentrations ·At higher concentrations, they can change the properties of bodies of water so as to prevent them from serving any useful purpose except navigation D.Sediments

·Sediments have direct and extreme physical impacts on streams and rivers ·Sediment entering waterways in large amounts has an array of impacts ·Modern storm-water management is designed to reduce the bed load E.Nutrients

·More nutrients mean more plant growth, so nutrients become water pollutants when they are added from point or nonpoint sources and stimulate undesirable plant growth in bodies of water F.Water Quality Standards

·The EPA has listed 167 chemicals and substances as criteria pollutants ·Two important applications of water quality criteria are the National Pollution Discharge Elimination System and Total Maximum Daily Load programs 17.2 Wastewater Management and Treatment

·Sewage borne bacteria were responsible to infectious diseases I.Development of Wastewater Collection and Treatment System ·To alleviate the problem of sewage-polluted...
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