Improvement of Water Quality to Reduce the Formation of Hazardous Disinfection By-Products Compounds

Abstract

The formation of disinfection by-products (DBPs) from chlorination in the treated drinking waters was determined. Formation potential tests were carried out to determine the carcinogenic THMs and HAAs. This study aims to two objects: The first is to determine the levels of THMs and HAAs in Greater Cairo drinking water over year of the study and compare it with the regulation in the Egypt law (458/2007), and the World Health Organization. The THMs and HAAs concentration was measured in seven different locations during 2014. The results indicate that the seasonal variation is below the critical values stipulated in the state, WHO and Egyptian regulations (seasonal average 45.14 ± 9.23 μg/l). In conclusion, it can be inferred that the concentration of THMs and HAAs in the drinking water of Greater Cairo is not hazardous to human health. The second is to determine the factors affecting on the formation of THMs and HAAs in Greater Cairo drinking water. The formation of these by-products is controlled mainly by operating factors (Cl2 dosage, total organic carbon (TOC), pH, temperature of the raw water, bromide ion and the contact time with Cl2). So, the effect of all of these parameters was investigated in this study in addition to THMs formation potential and HAAs formation potential. The batch experiments showed that increasing Cl2 dosage leading to increase the formation of THMs and HAAs. The same trend was observed for the contact time and initial TOC concentration. pH 7.5 was recognized as the optimum value for formation of THMs and HAAs.