The Study Of Microflocculation-ultrafiltation Process Dealing With Yujia Lake

At present, the application of ultra filtration technology for water treatment becamemore extensive; however, the deep research for the performance optimization andmechanism is still worthwhile. In order for the target technology of microflocculation-ultra filtration, this paper is searching for the optimum operation mode ofcoagulation for the pretreatment of lake water ultra filtration, also comparing thetechnologies of coagulation-sedimentation-ultra filtration and direct ultra filtration,seeking for the feasibility and applicability of micro flocculation as the pretreatment ofultra filtration from three points: water quality index, organic molecular weight removearea, membrane pollution resistance. The conclusions are as follows:(1) Based on the analysis of orthogonal test and contrast experiment, the best kind ofcoagulation is aluminum sulfate for these ultra filtration components, and the mostsuitable quantity is40mg/L; furthermore, the optimum hydraulics are: fast stir intensitiesare300r/min with10seconds,150r/min with4minutes,50r/min with10minutes.(2) The removal rate of turbidity for micro flocculation-ultra filtration technology isas high as95percent, which illustrates the removal rate of turbidity for this technologycannot be influenced by the inflow water quality; for this experiment, the removal oforganics could be as high as65percent, which indicates this technology can get a relativehigh removal rate for the organics.(3) The micro flocculation-ultra filtration technology is much better than the othertwo for the improvement of membrane flux and removal rate of organics. The main reasonis that the filer cake layer formed on the membrane surface by the coagulation constituentcan reduce the membrane resistance, expand the organic molecular weight remove areaand enhance the removal rate of each organic molecular weight area.(4) The membrane pollution resistance of the micro flocculation-ultra filtrationtechnology is less than the other two, the main reason is the filer cake layer formed on themembrane surface by the coagulation constituent can effectively reduce the membraneinternal adsorption resistance caused by the SCOD between30kDa and6kDa of molecularweight distribution. (5) The membrane internal adsorption resistance of the micro flocculation-ultrafiltration technology is smaller than the other two, which illustrates that the flocculationconstituent without precipitation does not enter ultra filtration membrane hole but stay onthe membrane surface, and also increases the filer cake layer resistance of it.