DISINFECTION OF DRINKING WATER-CONSTRAINTS AND OPTIMIZATION PERSPECTIVES IN ALGERIA

Abstract

Drinking water is disinfected to inactivate waterborne pathogens. The most common form of disinfection is chlorination, although ozone and UV light are also used in some plants of the world. Disinfection equipment depends on the type of disinfectant used. In developing countries, the water disinfection problem is large and complex. There are a number of appropriate methods but chlorine continues to be one of the most popular options. In Algeria, it is the only method of disinfection used. Chlorine is a very effective disinfectant, it is relatively easy to handle, the capital costs of chlorine installation are low, simple to dose, measure and control and it has a relatively good residual effect. Chlorination efficiency depends on chlorine residual, contact time, type of chemical used, location in the treatment process, and on characteristics of the water being treated. The chlorine demand involves the reaction of chlorine with compounds in water, reducing the amount of chlorine available to kill microorganisms. Chlorination of humic substances in drinking water is known to produce mutagenic and carcinogenic compounds such as trihalomethanes. Because of their chemical quality, Algerian waters could lead to complex and competitive reactions during chlorination step. The widespread detection of chloroform and other organohalogenated compounds contamination in the water reservoirs appear to be largely a consequence of the use of chlorination for the disinfection of drinking water. Those documented as probable human carcinogens and mutagens have been detected in large amounts and have been considered as the major component of DBPs. Taking into account above drawn conclusions, greater efforts are needed to evaluate and set priorities for drinking water disinfection in Algeria. The challenge is to maintain the level of microbial protection while minimizing the exposure of the consumers to DBPs. If disinfection by chlorination is maintained, the best way to reduce THM generation is to reduce the concentration of precursors through various water treatment techniques prior to chlorination.