Advanced Treatment Process For Rural Scattered Sewage By Ceramic Membrrane

In this paper, On-line coagulation with the combination of ceramic membrane technology for rural scattered sewage advanced treatment. Mainly to study the impact of various factors ceramic membrane flux (trans-membrane pressure, cross flow rate, permeate time, feed concentration, and filtrate particle size, etc.) on membrane flux and COD removal rate. And using gray relational analysis method analysis the affect of various factors; the introduction of online coagulation with a combination of ceramic membrane technology for rural decentralized sewage filtration experiments carried out to study whether the yielding water of domestic sewage come up to reuse standards; the establishment of appropriate physical model of the pollution mechanism to study the pollution mechanism during the experiments, and to guide the work of ceramic membrane cleaning.First, the five major factors which affecting the membrane flux and COD removal were discussed by analyzing the impact of a single factor, and on the basis of experiments, using gray relational analysis method to evaluate the major factors affecting the evaluation of reveal the main factors on membrane flux and COD removal rate of the degree of influence, a comprehensive analysis can be received. Ultimately, the relatedness of grey relation analysis can establish the main factors for the ceramic membrane to run experiments and to guide practical application of the, save a lot of time that looking for the best operating conditions of the exploratory test. The results showed that the minimal impact factor is cross-flow velocity, the main influencing factor was the trans-membrane pressure with regard to the membrane flux; trans-membrane pressure was also the main significant impact factor to the COD removal rate, followed by filtration concentration, other factors were not obvious. The experiments with the filtrate particle size 2.09μm, cross flow rate 1.0m/s, 20min, trans-membrane pressure changed were conducted, in connection with trans-membrane pressure and filter concentration experiments , The results demonstrated that the optimal operating pressure was 0.15Mpa, the best filtering concentration was 0.7g / L.On-line coagulation with the combination of ceramic membrane technology for rural scattered sewage advanced treatment, the results showed that the membrane flux decline trend is almost the same in different kinds of coagulant; the best treatment effect was calcium oxide; the treatment effect of running time was not obvious in the experiment, treatment effect when 30min was the best; operating pressure had relatively large effect on membrane flux, summing up the above ,the best operational pressure was 0.2Mpa; feed coagulant concentration had a relatively small influenced on membrane flux.0.8g/L-1.0g/L was the best dosage range operation in combined with treatment effects and cost. The test of ceramic membrane filtration water showed the quality of domestic sewage had reached the recycling quality standard. The water quality targets were achieved in recycling life miscellaneous water quality .so the water can be used to flush the toilet, watering plants, car washing, wiping and other miscellaneous life, and also reused to the same water quality requirements for other purposes, had significant environmental benefits, social benefits and economic benefits.The second concerned the fouling mechanism of ceramic membrane, this paper builded and the Field modified model to model the experimental data. From the results obtained in Field's modified model , different concentrations of CaO solution were mainly controlled by the "complete blocking ", the influence of concentration on fouling mechanism was not great; trans-membrane pressure had a certain effect on membrane fouling mechanism, membrane fouling mechanism mainly controlled "completely blocking" and "standard blocking"; the impact of cross-flow velocity on membrane fouling mechanism was greater, with the cross-flow velocity increased, the leading control membrane fouling changed from the "complete blocking" to the " standard blocking"; filter object also has some influence on membrane fouling mechanism, The physics properties more similar , the more similar mechanism. It was observed that the fouling mechanism mainly controlled by "complete blocking" and "standard blocking" mechanism, no"cake filtration" filtration process. And macromolecular substances into the membrane around the hole reunion, the formation of bridges when pore diameter is large but it is not easy to form a cake layer near the membrane surface.In the cleaning, the interval backwashing by clean water have better result than the simple backwashing, when the interval backwashing time was 2 minutes, the result is best. On practical engineering, the consumption of energy and cost were more reasonable. Whether it is acidic or alkaline cleaning agent , for the recovery of membrane flux is significantly superior to the direct clean water backwashing. When using these cleaning to clean the membrane fouling, cleaning time can be significantly reduced, the backwashing result is not much improved when time prolonged , result in energy waste and high costs.