Effect On Membrane Cleaning And Control Of Chemically Enhanced Backwash By Products In Coagulation-Ultrafiltration Process

With the progress of society, development of economics as well as the sharply increase of population, water resource is becoming increasingly serious in China. The lack of water supply capacity, the large scale increase of water demand, and the serious water body pollution, etc., these facts has throttled the economic development in our country, at the same time added more challenges to traditional water treatment. In order to accommodate the quality requirement of drinking water, more and more innovative water treatment techniques were developed. Membrane has become an important breakthrough due to its technological advantages, which is one of the most promising technologies before the 21 th century. While during the physical separation of membrane, the removal rate is low for middle size or small size particles. Therefore, it will cause serious membrane fouling.Chemical cleaning is definitely an effective solution, but on the other hand it probably causes secondary pollution, which brings more risk of safety. The research focused on developing a test method for chemically enhanced blackwash?CEB? on the basis of using coagulation-ultrafiltration device. Meantime, the determination method was developed to analyze the byproducts?BPs?, which were generated by the interaction between cleaning agent and contaminants. The BPs were classified and screened to determine the typical chemically enhanced blackwash byproducts?CEBBPs?. The hydraulic parameters of backwash, such as pressure, flux, time and cycle, were adjusted to observe the formation of CEBBPs, the effects of membrane cleaning. The influences of these parameters on the formation of CEBBPs and the effects of membrane cleaning were investigated. Finally, the optimal parameters of CEB on line were determined to optimize the membrane cleaning.The olatile halogenated organic compounds and haloacetic acids were determined by Headspace Tandam Gas Chromatography and PLC-MS/MS, respectively. 12 types of olatile halogenated organic compounds and 9 types of haloacetic acids were detected in effluent. The haloacetic acids almost took accunts of 85%. The concentrations of all the CEBBPs were decreased with the increase of runtime. The results showed that the optimal time, cycle, concentration and flux wer 4 min, 120 min, 25 mg/L and 20L/?m2·h?, respectively, which were determined by comprehensive consideration of the influence of single factor on the formation of CEBBPs and effect of membrane cleaning. The carcinogenesis risk assessment was conducted to evalute potential hazard of typical CEBBPs to human health. The risk quotients of the total CEBBPs was 52.881×10^-6.