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Show PART II PRESENT STATUS enterovlruses such as coxsackie, polio, and Infectious hepatltus viruses. Man Is the primary source of pathogenic bacteria and enteroviruses. Parasitic worms such as hookworms, flukes tapeworms and free-living worms such as chironomids and tubifex should be absent from domestic water. Manufacturing Water Use Generally, water of quality acceptable for domestic water use is acceptable for manufacturing water use. Water quality requirements vary significantly between different manufacturing industries. Even within a given manufacturing plant, water may have several different uses with different quality requirements for each. Cooling, steam generation, pro- cess, sanitary and other manufacturing water uses all have characteristic water quality requirements. Cooling water is required in virtually every manufacturing industry. The initial temperature of the intake water should be low, particularly if a once-through cooling system is used. Low initial temperature is desirable if a closed or recirculating cooling system is used, although the water will eventually be cooled by some mechanism such as a cooling tower. Wooden cooling towers are subject to physical, chemical, and bio- logical deterioration. High temperature water can cause physical dete- rioration. Chemical deterioration is caused primarily by high chlorine residuals and high alkalinity concentrations. Biological growth and slime in cooling system water can cause biological deterioration of wooden cooling towers and corrosion and loss of heat transfer within the cooling system. Corrosion and scale formation are significant detrimental effects of water quality on cooling and steam generation systems. Corrosion is caused by the chemical or electrochemical attack on a metal by its environment. High oxygen and carbon dioxide concentrations and low pH are the primary quality characteristics contributing to the corrosion of ferrous metals (5). Low pH, ammonia, cyanides, hydrogen sulfide and sulfur compounds are the principal contributors to the corrosion of non-ferrous metals. Because of evaporation and resulting concentration of chemical constituents, corrosion is a more acute problem in closed and recirculating cooling systems than in once-through open cooling systems. Scale formation results from the crystallization or precipitation of salts from solution. As temperature increases, the solubilities of scale forming salts decreases, making scale formation a major problem in cooling and steam generation systems. Many other factors such as operating pressure, boiler design, makeup rates and steam uses affect boiler scale formation (22). The primary detrimental effects of scale 20 |