| field. Continuous micro filtration-submersed (CMF-S) is characterized by large filtering areas, convenient installation and operation and stable effluent quality; reverse osmosis (RO) can achieve high desalination rate. The Combination of the two kinds of membrane technologies can greatly extend the scope of reclaimed water reuse and improve system resistance to shock-loading. This paper uses small experiments of CMF-S, RO and pilot test of combined process to reuse the effluent of the coagulation and sedimentation processes, which is the pretreatment for the secondary effluent from a municipal wastewater plant. Based on product water quality of double film system, this paper mainly focuses on the following respects.(1)The CMF-S trial experiments showed that, under the condition of water quality, the best filtration cycle is 50 minutes,the optimized backwash mode is using air to scour the pollutant for 40 seconds first, then using air-water backwash to take away the pollutant for 15 seconds; dosing sodium hypochlorite at regular intervals will degrade the chemical cleaning process, so the dosage and frequency of sodium hypochlorite should be reduced on condition that the technological requirement was satisfied, dosing hydrochloric acid at regular intervals can improve the efficiency of chlorine chemical cleaning.(2)The parameters optimization experiments of CMF-S pilot system under three loading conditions (low, medium and high) in summer were carried out. The results showed that, compared to the original technology operation paramers, the transmembrane pressure differential recovery rate and membrane pollution rate of the best operation paramers are in general improved under low and high loading conditions. So in both cases, the technology operation paramers can be adjusted to improve operation efficiency and save operating costs. At last, according to operation data of the CMF-S system, theâ–³TMP multiple linear regression model can be obtained by way of correlation analysis and multiple linear regression analysis, and the fitting effect is good. The removal efficiency of CMF-S system is high and stable for turbidity, but is not good for soluble substances.(3)The RO membrane filtration test was conducted by different raw water, which used sodium alginate and humic acid and bovine serum albumin as models of kinds of different organics. The results exhibited that sodium alginate can form dense pollution layer on the membrane in early operation period, and the pollution differences caused by the concentration gradient are not notable in late operation period. Bovine serum albumin form gel pollution layer on the membrane surface and the pollution rate flattens after a rapid change. The descent rate of membrane specific flux caused by hydrophobic humic acid is quite slow, which can form rough pollution layer and block fouling on membrane surface, moreover it is susceptible to the filtration flow condition. When calcium ions exist in sodium alginate solutions, organic pollution will be increased to a high degree which is concerned with the concentration of calcium ions.(4)The operating stability of reverse osmosis pilot system was analyzed, and a penetration flux model can be obtained by means of the linear regression and significant inspection of the pilot test data. The model provides research foundation for later establishment of RO cost model. |
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