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Show PART II PRESENT STATUS formation are the retardation of heat transfer and the overheating of boilers resulting in failures. Calcium carbonate, magnesium silicate, and calcium sulfate are the principal chemical constituents of scale formation (5). Water quality requirements for manufacturing process water uses vary widely. The food and kindred products industry requires process water which is free of pathogenic bateria and enteroviruses and free of sapro- phytic organisms that may cause spoilage. Various chemical constituents must be limited to prevent undesirable tastes, odors, colors, deposits, toughening or deterioration of quality or vitamine content (32). Some chemical constituents in water produce desirable and beneficial reactions. The lumber and wood products industry generally requires process water which is free of suspended solids greater than 3 mm in diameter which may damage equipment. The pH should be between 5 and 9 to prevent equip- ment corrosion. Water for preparation of solutions for treatment of the lumber should be reasonably free of turbidity and those ions which might react to form precipitates (22). The chemicals industry may require water as a reactant (a substance that contributes its atoms to the final product) or as a solvent (3). Chemical constituents of the water which might cause adverse chemical reactions must be limited. Generally, firms in the stone, clay and glass industry, particularly ready-mix concrete firms and firms producing concrete products, require water which is clean and free of oils, acids, alkalis, salts, and organic materials (2). Decaying vegetable matter may interfere with the setting of cement (32). Livestock Water Use Livestock water quality requirements are satisfied by water which is satisfactory for domestic water use, although it appears livestock can tolerate water of lesser quality. High dissolved solids concentrations are the most common livestock water quality problem. High concentrations of dissolved solids in the form of salts can cause physiological distur- bances in animals such as gastrointestinal symptoms, wasting disease, and death. Animals whose productivity depends upon such functions as lacta- tion, reproduction and rapid growth may have these functions impeded by high salinity concentrations. There are indications that low concentra- tions of some compounds such as nitrates, fluorides, and the salts of selenium and molybdenum can be specifically toxic to livestock. Limits of dissolved solids concentrations for various livestock are shown in Table 8. (22) 21 |