Study On Distribution Of Typical Toxic Organic Pollutants In Three Gorges Reservoir Area's Water Treatment Plants

PAHs and PAEs, many compounds of which are listed by American Environmental Protection Agency as Priority-Control Organic Pollutants, are typical environmental toxic organic pollutants. After Three Gorges Project was impounded to water level of 156 metres, it changed much in water quality and hydrology of rivers in reservoir area, and water quality is the key to evaluating the administration and engineering of the reservoir. It is necessary to carry out the study on PAHs and PAEs in influent and effluent water of water treatment plants in reservoir area. It especially makes sense to ensure water supply safety and protect aquatic environment in reservoir area.In the study PAHs and PAEs were screened out as target substances. Microporous membrane filtration, liquid-liquid extraction and GC/MS were adopt to determine concentration level of PAHs and PAEs in influent and effluent water of 4 water treatment works in reservoir area. In October, 2005 and between May and July, 2006 influent and effluent water of 4 water treatment plants were sampled and ananyzed. Then in January 2007 preliminary study was carried out on controlling effect on PAHs and PAEs by two typical water treatment technologies.In dry period 130 organics were detected in influent and effluent water of the water treatment plant, in which dominated by alkane, alkene, organic acid, ester, ketone, phenol and amine. 3 kinds and 13 typical toxic organic pollutants were detected. 8 of them were EPA priority-control organic pollutants and 3 of them were SEPA priority- control organic pollutants. Detection rate of fluoranthene, pyrene, phenanthrene and PAEs was rather high. Generally speaking, Organic contamination trend of Yangtze River aggravate from upstream to downstream. But Yangtze River was less contamined then other river systems. It showed out that self-purification of water area in Three Gorges and it was less contaminated by organic pollutants.8 PAHs, 5 PAEs and rogor were detected in influent and effluent water of 4 water treatment plants when unusual great drought happened in reservoir area. But concentrations of them didn't exceed limited value of related laws. The source of PAHs was mixed sources of pyrolysis and petrol discharge. The source of rogor was point- source discharge of pesticide plant.Concentrations of target substances in 2 typical water treatment technology decreased after treated. But the controlling effect of water treatment technology to target substances was quite limited. Concentrations of them after filtration increased a lot.Relativities of concentrations of PAHs, PAEs and organic contamination indexes such as TOC, UV₂₅₄, COD_Mn were analyzed. Relativity of TOC was better than UV₂₅₄ and COD_Mn. But all of them were quite low. And the three indexes were not suitable to be substitute of PAHs and PAEs.