Study On Water Quality Changes And Pollution Control Of Feng Valley In Xi'an

Based on the monitoring datum of surface water quality and some relative statistics of nature, economy and society, the trend and law of water quality changes of Feng River and their coupling relationship with development of society and economy were discussed.By investigation on the valley, the main pollution sources and the key pollutants were found, and experiment was conducted to tread restaurant wastewater by the aerobic membrane bioreactor. The results showed:(1) Two phases: accelerated deterioration and slow deterioration of water quality changes were divided. There is only a little relationship existed between precipitation and water quality changes. Trend of water quality changes was mainly related with the pollution produced by industry of village, breed livestock and people-living.(2) The formula of index of organic pollution and their coupling relationship with development of society and enconomy were discussed.(3) COD, BOD and volatile phenols were found to be the key pollutant in Feng River .The polluted characteristics of the key pollutant in Feng River was found in three parts: â‘ The rule of seasonal change of the key pollutant was clear and obvious. â‘¡From upper to lower part, the coutents of the key pollutant increased. â‘¢The ground water quality of Feng River is deterioration frome 1986 to 2001. Restaurant wastewater from u p-stream of Feng River ,paper-making wastewater and domestic wastewater from down-strew of Feng River were fourd to be the main pollution sources of Feng River.(4) There were three main pollution sources in Feng Valley. To counter this situation, we should use different ways to control them. â‘ Domestic wastewater should be treated by sewage treatment plant. â‘¡Paper-making wastewater should be treated by chemical process and coagulative treatment. â‘¢The experiment was conducted to treat restaurant wastewater by aerobic membrane bioreactor (MBR). The results showed that MBR had some advantagesincluding superior effluent quality, compactness, low sludge generation and resistance to shock loads. This process is suitable to treat the small quantity and high concentration wastewater.Research result suggested that under the condition of 4000~5000mg/L MLSS, 0.98~2.27kg/m3.d COD volumetric load, 22-24 hours HRT and 100 days SRT, the MBR was operated well, and the effluent quality could meet the national wastewater discharge standard.