Water, potable municipal supplies

Multimedia pressure filters can be used as stand alone treatment, when the feed sources is relatively clean water, such as a potable municipal supply, or in series with clarification, for river and other surface waters. 

Water. Water mains should be connected to plant fire mains at two or more poiats, so that a sufficient water supply can be deHvered ia case of emergency. The plant loop and its branches should be adequately valved so that a break can be isolated without affecting a principal part of the system. If there is any question of maintaining adequate pressure, suitable booster pumps should be iastaHed. Any connection made to potable water for process water or cooling water must be made ia such a manner that there can be no backflow of possibly contaminated water check valves alone are not sufficient. The municipal supply should faH freely iato a tank from which the water is pumped for process purposes, or commercially available and approved backflow preventers should be used. 

Municipal supplies whilst often arising from one or several of the sources listed above are frequently pretreated by the Regional Water Authority in order to meet the requirements for potable quality laid down by The European Community directives given in Table 8.2. 

Reverse osmosis is a process that transforms an unusable water supply into a usable resource. It is capable of renovating a broad spectrum of feed-waters from municipal water supplies that need polishing for industrial purposes to seawater that is refined into a potable water supply. Table 4.23 shows the different types of feedwater being processed by reverse osmosis units. Seawater is considered to have a nominal total dissolved solids (TDS) content of 35,000 mg/C. Wastewater is from industrial or municipal sources and the TDS is variable. Brackish water is defined for the purposes of Table 4.2 only as a water that may have a TDS from that of municipal water supplies up to 10,000 mg/G. 

General quality improvement of present supplies Upgrade total municipal supply Potable water from degraded supplies Brackish water desalination Seawater desalination... 

Under utilities should be included the costs for items that enter the plant but do not enter directly into the material formulation of the products or by-products. This includes coal, oil, gas, electricity, water, air, and inert gases. The amounts of cooling, process, and potable water should each be specified. Potable water is water that can be used for drinking and food preparation. It is usually purchased from a nearby municipality. The average electrical power required, peak power required, and demand power need to be calculated. Demand power is the number of kilowatts of energy that the utility company agrees to supply on an uninterrupted basis. A premium price is charged for this power. 

Water and Feed. Like all animals, pigs should be permitted free access to potable water, preferably from a municipal water supply intended for human consumption. Drinking water intended for pigs does not have to be filtered or deionized. Various diets have been described. Because of their size (i.e., high maintenance charges and test articles demand), pigs have seldom been used for chronic studies where the possibility of waterborne envinronmental contaminants could influence a study. 

Sources include surface waters, wells, seas and estuaries, and recovered condensate. Many plants serve all their needs with municipal water, treated to potable quality, which may be based on surface water or well water. Public water supplies usually carry a firaction of a ppm of chlorine. When used as the principal supply to a plant, these must be dechlorinated before most direct uses in the process. 

Some plants also produce their own potable water by treating a well or groundwater supply. This is not a common situation, and it is a specialized subject that will not be covered here. Most plants receive potable water from a local supplier or municipality. This water is used for drinking and sanitary use and usually in safety shower/eye wash systems. In some cases, the municipal potable water supply also serves as a general plant utility. Drinking water systems must always be kept separate from plant service systems. The method of separation is often prescribed by local regulations. Backflow preventers are a standard, but dedicated tanks that provide physical breaks are more positive and in many locations are required. These are discussed in Section 12.7.2. 

Potable Water. Every plant must have a potable water supply, and many use some of that water in other applications. Small plants in particular may receive all their water from local municipal (potable) systems. It then becomes necessary to prevent the backup of water connected to process systems into the drinking water system. 

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