Papers by Author: Jie Wang

Abstract: The effect of aggregated floc circulation on membrane fouling in contact circulated coagulation-membrane filtration hybrid process for treatment of surface water was investigated in this study. In order to understand the floc characteristics, the floc formation, breakage and re-growth were monitored by Mastersizer 2000 under the coagulation dosage of 5, 10, 15 and 20mg/l. A contact circulated coagulation tests were carried out and the effluent was filtered by a dead-end micro-filtration with the hollow fibre membrane. The coagulation effluent quality and the relative permeability J/J₀ of membrane was determined at the circulated floc dosage of 22, 44 and 66mg/l. The experiment results indicated that the addition of circulated floc obviously improved the flux decline and the degree of improvement was closely related to the dosage of circulated floc. Compared to traditional coagulation, the contact circulated coagulation was an economic and efficient method to retard the membrane fouling.

Abstract: Based on the characteristics of non-uniform distribution in the fouling of hollow-fiber membrane, the non-uniform distribution of local flux and redistribution with different fiber length (0.6 m、1.2 m、1.6 m) was investigated experimentally. Experiment was conducted under the condition of operating flux 20 L/m²h (20 LMH). The results indicated that the longer fiber length was, the greater difference in local pressure and the more non-uniform the local flux distributed. Under operating mode of critical flux, the flux distribution in the length of 1.6 m membrane fiber is the most non-uniform with the fastest fouling rate. In addition, the distribution of local flux is more uniform for 0.6 m fiber under the operating flux of 16 LMH, which also slow down membrane fouling significantly. Shorter membrane fiber generally exhibited higher uniformity in the local flux distribution and slower development rate of membrane fouling.

Abstract: In the present study, an orthogonal array design was adopted to investigate effects of operational parameters including aeration intensity, membrane configuration and fiber length on membrane fouling in a lab scale. Mean membrane permeability decrease rate over the operation time was used to evaluate membrane fouling rate (MFR). In a constant pressure filtration mode of 15kPa, fiber length and aeration intensity were found to have a negative influence on MFR，and membrane configuration also had an obvious influence on MFR. The three factors in influencing MFR is in the order of fiber length>module configuration>aeration intensity. The experiments results also showed that the mean specific permeability displayed a slightly rise in the range of 60-100cm and the modules of two permeate outlet attain the best mean specific permeability in all the modules. According to this work, it show that membrane module design have a significance on membrane optimization.

Abstract: Adopting standard k-ε turbulent model and mixture flow model, settling process and decant process was simulated using 3-d numerical simulation in M-ICAR(Mixture-Intermittently Cycle Aeration Reactor) process to analyze the changes of sludge phase volume fraction. The simulation results showed that the changes of feeding wastewater had great influence on sludge settle ability in decant process, and the position of decanter needed optimized; it had no influence on sludge settle ability in settling process. For considering the lowest hydraulic retention time, the research controlled maximum feeding wastewater for 1610m3/h. Internal recycle had no influence on sludge settle ability. Two methods were proposed: the first one, the water level of decanter was set 3.9m (sludge volume fraction of this suspended area was less than 0.05), feeding velocity was 0.07 m/s; the second, keep the water level of decanter 3.75 m, reduce feeding velocity (preliminary setting feeding velocity 0.06 m/s). The two methods had no influence on sludge settle ability.