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(T/EH123) The occurrence of trihalomethanes in supply water and the trihalomethane potential formation for groundwater sources in Hanoi City. Duong Hong, Anh1, Hoang Minh, Hang1, Pham Hung, Viet1, Michael, Berg2, Walter, Giger2, 1 2 ABSTRACT- An investigation into the occurrence and fate of trihalomethanes (THMs) in public drinking water in Hanoi city has been conducted from 1998 to 2001. The concentrations of the total THMs at the outlets of the 8 major drinking water plants were actually below the guideline value recommended by the WHO (100 mg/l), partly due to the low chlorine dose being applied. Three water plants were chosen to investigate the fate of the THMs in the drinking water distribution system. The obtained results showed highest concentrations of THMs in the outlets of the water plants and generally decreased with increasing distance. Bromotrihalomethanes were the predominant THMs, whereas chloroform was the least prevalent species. The trihalomethane formation potential (THMFP), the bromide incorporation factor, and the correlation between chlorine consumption and the THM formation of typical groundwaters of Hanoi were investigated in the laboratory. The study revealed that bromide and especially ammonium present in the raw groundwater has a significant influence on the formation and the composition of THM species. For comparison with groundwater, laboratory chlorination experiments with raw surface waters that are used as drinking water resources in some provinces in the North of Vietnam have also been conducted. Key words: Trihalomethane, Trihalomethane Formation Protential, Ammonium, Chlorination |
