Experimental Study On Short-process Water Purification Process Using Flat Sheet Membrane By A Hydrostatic Pressure-flow Way

Short-flow process, the raw water directly enters into a submerged ultrafiltration membrane to filter after appropriate pretreatment, at the same time concentration of water recycling and sludge thickening are finished in the membrane pool, the filtered water by adding a small amount of disinfectant enters into the clear water tank. Compared with the traditional process. Compared to traditional water purification technology, short-flow process refers to its processes significantly shortened, the short-flow process weakens the sedimentation function, treatment process is significantly shorter, covers an area of significantly narrowed. The distinct advantages make short-flow process with submerged ultrafiltration membrane as the core to be more and more attention. It makes ultrafiltration the most promising drinking water treatment technologies.In this paper, using PVDF flat ultrafiltration membrane by hydrostatic flow way short-process purification on the Yangtze water was studied. This paper studied the removal efficiency of short-flow process on the raw water contaminants and operating conditions affecting the membrane fouling, investigated the flat membrane pollution mechanism and control measures, calculated the value of the membrane filtration resistance, deduced the mathematical model of permeate flux with time and transmembrane pressure. The main findings were as follows:(1) Short-flow process effluent turbidity≤0.1NTU. turbidity removal efficiency of96.28%to99.86%; Permanganate index removal rate was between30%to50%; Ammonia removal rate as the study progress gradually reduced from93%to27%; The effluent pH was slightly lower than the influent pH value; The total hardness, chloride removal were respectively in3.5%～15%.2.4%～16%; Total iron, total manganese removal rates respectively were85%～95%,35%～60%. When these water quality indicators content in source water were less than drinking water quality standard limits, the effluent water quality indicators could meet drinking water health standards (GB5749-2006) requirements.(2) The removal rate of UV254is from3%to50%, the effluent UV254was not influenced the influent UV254value, remained between0.021and0.031cm-1and met the water quality requirement; When short-flow process influent content of TOC was less than3.5mg/L. the effluent content of TOC could achieve high-quality drinking water quality indicators; It was very unlikely that Giardia’s insects, Cryptosporidium and other pathogenic microorganisms were in the effluent water, the effluent water did not contain E. coli, hexavalent chromium, the bacteria number also met drinking water health standards.(3) Within a certain range (≤15mg/L) increasing coagulant PAC dosage could reduce the membrane flux decline rate, alleviate the membrane fouling; The flat membrane fouling total resistance Rr of short-flow process was derived1.63×1010m-1by Darcy formula, indicating the membrane fouling of short-flow process was at a low level.