Development of Sanitary Treatment Methods of Membrane Wash Wastewater from Drinking Water Purification Plant

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Evaluation of safety aspects of microorganisms in membrane wash wastewater : Using bacteria and coli phage as index of microorganisms, their removal performance by membrane filtration, concentration in the membrane wash wastewater and entrapped amount insid the membrane were investigated. The bacteria and larger size phage were almost separated by micro-filter and they were flushed out to the washing wastewater. The phage, Q beta , which was smaller than the pore size of membrane, was partially removed by MF but the separated phage was not whole discharged to the wash water.Thickening of membrane washing wastewater : Three types of thickening method, that is electrolytic coagulation/settlement, granular filtration, and settling/membrane filtration were investigated. The settling/membrane filtration could produced as good quality filtered water as drinking water. The electrolytic coagulation/settlement process could discharge the highest concentrated sludge. Higher concentrated sludge w … More as obtained with the iron anode than the aluminum anode, and better supernatant quality was gotten with the aluminum anode than the iron anode. The granular filtration was inferior to the other methods in both the separated water quality and the sludge concentration.The membrane filtration technology considering washing process : It happens in outside-in mode hollow fiber membrane filtration that the sludge accumulates around and between the membrane fibers. The inter fiber clogging was caused under the condition of lower flow rate than critical cross flow speed. The critical cross flow speed was 0.7m/s and shear strength at the speed was estimated 200Pa.Membrane filtration with pilot scale plant : Actual raw water was applied for the polyethylene micro-filter membrane filtration. Sterilization such as chlorimation, ozonation or ultra-violet radiation before filtration were efficient to reduce trance membrance pressure rising. The substances separated by membrane and chemical washing wastewater contained polysaccharide, protein, peptide, and amino as well as polycyclic-ring aromatic compounds. Less