PMIA Hollow Fiber Membrane Fouling Mechanism And Its MBR Process Wastewater Treatment Research

This thesis selected the aromatic poly(m-phenylene isophthalamide)(PMIA)hollow fiber membrane was fabricated by dry-wet spinning technology and homogenous enhanced PMIA hollow fiber membrane as research object.Firstly,the fouling mechanism of two kinds of membrane was determined by experimental data fitting to pore blocking model or cake fouling model.The fiter mediuns which could induce fouling included CaCO3 suspension,activated sludge and BSA.Secondly,the fouling type of two kinds of membrane were verified by membrane pore size distribution,particle size distribution of filter mediums,and the membrane resistance distribution during ultrafiltration.The results showed that the membrane fouling caused by CaCO3 suspension and activate sludge were conformed to cake layer formation.The main type of the membrane fouling in ultrafitration of BSA was attribution to pore blocking.Morover,under the same operating conditions,the fouling of two kinds of membrane caused by activated sludge was most serious.At the meantime,the physical irreversibleof homogenous enhanced PMIA hollow fiber membrane was easier to remove than PMIA hollow fiber membrane that was fabricated by dry-wet spinning technology in the aspects of adsorbability and physical cleaning effect.Then,the filtration performance of the NIPS PMIA hollow fiber membrane and homogenous enhanced PMIA hollow fiber membrane in MBR system was studied by treating domestic sewage.In addition,the cleaning effects of water and chemical water analyzed by field emission scaning electron microscopy(FESEM)and energy dispersive X-ray apectrometer(EDX).The results firstly showed that the effluent water qualities of both membranes were good,the average removal of COD?NH4+-N up to 95%,the average removal of TP up to 67%.Secondly,no matter what kind of cleaning method,the TMP recovery rate of M2 was higher than Ml,and the stain resistance of M2 was stronger than Ml.Thirdly,the TMP recovery rate after hydraulic backwash of M1?M2 was 49.12%,80.43%,respectively;TMP recovery rate after the second hydraulic backwash was 34.37%,50.00%,respectively;TMP recovery rate after chemical cleaning was 65.52%,65.52%respectively.Morover,with the aggravation of fouling in the MBR system,the cleaning effect of chemical was better than water cleaning,the pollutants were easier to be removed by chemical cleaning.At last,the feasibility of homogenous enhanced PMIA hollow fiber membrane was investigated in the MBR system to deal with pNitrophenol wastewater(PNP).At the same time,it was significant to improve TP removal efficiency after adding aluminum sulfate.In addition,the cleaning effect of ultrasonic wave concussion was analyzed by field emission scaning electron microscopy(FESEM)and energy dispersive X-ray apectrometer(EDX).To find the best time of ultrasonic wave concussion by discussing different ultrasonic oscillation time impact on cleaning effect.The results showed that the effluent water qualities of homogenous enhanced PMIA hollow fiber membranes were stable.Furthmore,the removal efficienvy of TOC?PNP?NH4+-N was 96.84%?91.09%?89.09%respectively.In addition,After choosing aluminum sulfate as the flocculating agent,the average of TP removal was.87.21%.And the optimum ultrasound cleaning time of homogenous enhanced PMIA hollow fiber membrane was 90min which achieved good cleaning effect.