Research On Application Of Combined The Biological Technology Using Multi-medium Stuffing With The Ultrafiltration Treatment Technology For Polluted River Water

Due to the drinking water sources generally polluted, challenges for DWTP lie in the overgrowth of microbial in summer and the decrease of removal efficiency of organic matter and ammonia which caused by low microbial activity in winter. Therefore, research and develop new and efficient water treatment technology has always been the research hotspot. Ultrafiltration process has been widely applied in water purifying filed for its distinguishing feature, such as stable effluent quality, wide pollutants removal range, low energy consumption and simple operation etc, especially when combine biological process with ultrafiltration process can effectively remove the pollutants in the polluted river water.This study used multi-medium as the carrier of biological technology system. A bench-scale biological technology system combined with ultrafiltration was established, and the optimal condition of this combined process was investigated through an orthogonal experiment under different test condition, and indicated that this combined process can efficiently remove ammonia, turbidity, organic matters, iron and manganese of the polluted river water, which located in Jiaxing.In order to realize the feasibility of this combined process, we expended the bench-scale study results to a pilot-scale experiment. The results showed that this combined process can ensure the effluent quality in both normal and low temperature period and reach the requirement of Standards for Drinking Water Quality(GB5749-2006).The research on the optimization of the ultrafiltration system mainly focus on three aspects, air cleaning, backwashing methods and chemical cleaning, respectively. The results of air cleaning experiment indicated that the best cleaning effect occurred when the liquid level reach the 3/4 of the membrane length. In addition, the orthogonal experiment of relevant parameters of the membrane module suggested that the optimal working condition should be that the membrane flux was 30 L/(m2·h), water production time was 40 min, the single water backwashing and washing time were 100 s and 40 s, respectively. Based on this result, ultimately determined the hydraulic cleaning method was combined water and air backwashing + washing by an optimization experiment. The study of online backwashing method showed that when combined water and air backwashing time was 70 s, backwashing flow rate was 2 m3/ h, air cleaning strength at 133.3 L/(m2·h), Online air and water backwashing can effectively alleviate the pollution of membrane system. According to the hydraulic cleaning method is difficult to eradicate the problem of membrane pollution, the effect of the on-line and off-line chemical cleaning on the recovery of transmembrane pressure was investigated. The results indicated that an online CEB cleaning could recover the performance of ultrafiltration system timely after 4 times of hydraulic cleaning, however, the system still need off-line cleaning to maintain its stable operation after a long-term operation.