EFFECT OF CHLORINATION ON WASTE WATER QUALITY PARAMETERS AND FORMATION OF TRIHALOMETHANES

Abstract

The behavior of COD, BOD, TOC and ammonical nitrogen of secondary effluents under varied concentration of chlorine was investigated. The three parameters (mainly) were measured in final effluents treated with different chlorine dosages in the range of 1-50 mg/L and 30 min contact time. Chlorine dosages above 10 mg/L resulted in increased BOD and COD level of the effluent, with chlorine dosages above 40 mg/L resulted in almost double the original BOD and COD values. TOC measurements showed obvious -stability against chlorine impact, which makes TOC a better indicator for the organic contents of wastewater. Almost all the observed increase in BOD measurements could be attributed to modification of dissolved part of the organic matter by chlorine The results also show that the response of BOD and COD to chlorination is a function of chlorine dosage and the organic content of wastewater. But chlorination of raw samples did not show the same degree of influence on BOD, COD and TOC when compared to secondary effluents because the effect of chlorination on BOD and COD diminishes with increasing the organic content of the wastewater. After chlorination of treated water at different chlorine dosages (1-6 mg/L) and at 30 min contact time, the level of chloroform are found above the regulated WHO guide line value of 200 Ixg/L, and dichlorobromomethane, chlorodibromomethane, bromoform found under WHO guideline.