Pollution Research Paper

ASSESSMENT OF TRIHALOMETHANES LEVEL OF BENGHAZI CITY WATER DISTRIBUTION SYSTEM IN LIBYA

Aiman . M. Bobakar and Intisar . M. Alakili

Abstract

Chlorination is used as the main disinfection process for all drinking water supply system in Libya. However, recently was discovered that the use of chlorine posed potential health risks due to the formation of carcinogenic halo-organic compounds, as disinfections by-products (DBPs) and major of which is Trihalomethanes (THMs). It consists of four chemical species namely chloroform (CHCl3), bromodichloromethane (CHCl2Br), dibromochloromethane (CHClBr2) and Bromoform (CHBr3). The sum of these four compounds is referred to as Total Trihalomethanes (TTHMs). This study is aimed to investigate the presence of THMs in water distribution system of the Benghazi city, Libya. The network of water distribution system of the city was divided into three areas A, B and C according to the distance away from Al Talhya reservoir (water source). Water samples were collected once a month from the main pipeline of thirty six districts across the Benghazi city during the summer season three months of July, August and September in 2012. A rapid and simple EPA 551.1 modified method for THM analysis by Liquid-Liquid Extraction (LLE) with methyl-tert-butyl ether (MTBE) and quantitative by gas chromatography/electron capture detector (GC/ECD) was used for identification and quantitative of THM in water samples under study. Some variables liable to affect the formation and concentration of THM in the distribution system were also investigated. These variables include temperature, pH, turbidity, total organic carbon (TOC), bromide ion (Br-) total and residuals chlorine. Presence of THMs in Benghazi city distribution system was observed in this study. The concentration levels of THMs followed the order CHCl3> CHCl2Br > CHClBr2 > CHBr3 in all samples. A wide variation in the TTHMs concentration levels was also observed. The highest level of TTHMs (113.421±57.995 μgL-1) was obtained in area C, which much higher than the EPA’s recommended Maximum Contaminant Level (MCL 80 μgL-1). However, the A and B areas were recorded as lowest levels of TTHMs (47.276±28.125μgL-1 and 65.8470±28.426 μgL-1, respectively) which met EPA’s recommendation. These results clearly indicated that, the Benghazi city network distribution system faced high level of THMs problem.