| Membrane bioreactor MBR has a good application prospect,which is considered as a new type of high efficiency water treatment technology. Recirculated membrane bioreactor(RMBR)is widely used in the treatment of industrial wastewater and Garbage leachate. However, membrane fouling problems seriously affect the normal operation of the system. Current research mainly focused on the membrane fouling in SMBR, Research on the sludge flocs properties of membrane pollution impact studies in RMBR is relatively lacking. This article utilizes the “anaerobic + aerobic + external type tubular membrane filtration technology”, mainly studies sludge floc breakage behavior and its effects on membrane fouling in RMBR circulation mode, analyze the effect of flocs properties change on membrane fouling, Interpretating that sludge flocs properties change sludge on the influence of membrane fouling,caused by floc breakage behavior. Mainly includes the following research contents and conclusions as follows:(1)Study the shearing force of centrifugal pump and the membrane tube on floc breakage behavior respectively in RMBR,employing coagulation Experiment to study to velocity gradient and the floc size relationship,and through theoretical deduced under the action of centrifugal pump shear floc size and pump speed and impeller diameter d approximate relationship: 0.63 1.05 d n D--? ?; Use shear wall function theory to analyze the membrane tube and the floc size relations, the results show that the theory can accurately reflect the membrane tube shear force influence on the floc size. put in practice and floc breakage phenomenon weight reflocculation after mechanical crushing sludge flocs condensation process, crushing the sludge flocs under certain conditions similar to the initial particle size distribution.(2)Using SPSS software analysis the sludge flocs properties and membrane fouling resistance correlation. floc size,Zeta potential, extracellular polymers(EPS concentration and membrane fouling resistance correlation coefficients were respectively 0.726, 0.784, 0.875. The floc size has most significant effects on membrane fouling resistance when its size in 20 um to 50 um; And from EPS structure respectively study the LB – EPS and TB- EPS the correlation to the membrane fouling resistance,and the results show that before running within 60 h, LB- EPS and membrane fouling resistance correlation is good; Then TB- EPS and membrane fouling resistance correlation is better. through comparing of membrane pollution resistance with EPS growth rate, the results show that the TB- EPS contributed more to membrane fouling.(3)Sludge floc breakage behavior is characterized by floc breakage rate,analyzes correlation of the added value of EPS and floc breakage rate, Results show that the mixture of EPS growth comes mainly from floc breakage process; Adopts correlation analysis to explore the floc breakage rate influences on resistance of membrane pollution, results indicated that the floc breakage is the main cause of membrane fouling, floc breakage behavior caused by sludge floc size and release of the EPS, resulting in a more serious membrane fouling. |
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