Water Treatment Plants and Disinfecting Water Uses of Chlorine
Guidelines set forth for water treatment professionals illustrate the process of using chlorine gas in a treatment plant (Kerri, 1989). Chlorine gas is fed into the water treatment system under vacuum supplied by various types of induction equipment. The entire chlorination piping system should be under vacuum to ensure safety. Chlorine tanks have a system of regulators to reduce pressure from the tank, feed equipment to accurately measure feed rate, and vacuum educators to deliver the chemical into the receiving water. Piping connections must be sealed with proper pipe thread compound to ensure pipe joints are not subject to chlorine attack, and compression fittings must be sealed with a new lead washer. When the system is first started, and each time an empty chlorine tank is switched for a new one, a simple ammonia check should be performed. Ammonia and chlorine combine to make white smoke, indicating a leak. At each point in the process, automatic and manual overrides exist if a leak is detected at any point. Chlorine gas scrubbers should be installed in any facility that uses chlorine gas. These scrubbers are designed to handle the volume of one tank in the event of a rupture. A leak detection system turns the scrubber on when a leak is detected, and the system scrubs one tank-volume worth of chlorine gas into a sodium hydroxide solution. The resulting combination of chlorine and sodium hydroxide is a 10 percent bleach solution which can then be used as a liquid form of chlorine.