Seasonal Variation in Drinking Water Disinfection By-products in Gharbia Governorate, Egypt

Chlorine is the most common disinfectant used in drinking water treatment because it is cheap and has an efficient germicidal ability. However, chlorine and organic matter reacting trihalomethanes (THMs) are suspected carcinogens. The major groups of disinfection by-products (DBPs) are THMs, haloacetic acids (HAAs), haloacetonitriles (HANs), and halogenated ketones (HKs). Exposure to these by-products increases the risk of cancers, abortion, low birth weight, and congenital disabilities. The wastewater contents of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), as the source of total organic carbon (TOC) compounds, are oxidized by chlorine to produce DBPs. This study aimed to monitor the seasonal levels of THMs in Egypt compared with international standards using capillary gas chromatography. Results revealed that THMs mean values vary between 9.26 to 35.86 μg/l, while dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) mean values vary between 3.82 to 17.74 μg/l and 4.41 to 13.25 μg/l, respectively. The maximum THM and TCAA values were observed during the summer, probably due to high temperatures. While the maximum DCAA values were observed during the autumn due to the high levels of raw water TOC. In conclusion, continuous monitoring of THM and its species is highly recommended, taking into consideration how climate can influence THMs formation.