| Because of the inhibitory effect of inorganic salts on microorganism and settlingperformance of sludge, it is difficult to treat saline wastewater by Biological method.MBR technology provides an opportunity for the efficient treatment of high salinitywastewater by biological method, because it can largely accumulat microorganisms andis not affected by the sludge settling sludge settling characteristics.The paper takes a good use of MBR process, which can gather in large numbers ofmicroorganisms and can be unaffected by sludge settle ability.Two membrane bioreactoranoxic and aerobic biofilm-membrane bioreactor and aerobic biofilm-membranebioreactor are used to treat mustard tuber wastewater with7%and10%ofsalinity.Experiments was carried out to study the treatment efficiency of mustard tuberwastewater treatment by membrane bioreactor and its fouling characteristics,andinvestigate the effects of operating conditions of the membrane bioreactor （MBR）salinity （calculated as NaCl） on membrane fouling rate, and optimize the operatingconditions of the reactor.The effect of salting out and halophilic bacteria characteristicson membrane critical flux was researched as well, to find ways to reduce membranefouling.Supported by the National Natural Science Fund Project “Influencing Mechanismof salting-out and halophilic bacteria on membrane pollution during high salinitywastewater treatment by MBR", more than a year of test was carried out. The mainresearch contents and results are as follows:①Pollution characteristics of membrane bioreactor treating mustard tuberwastewater of high salt was researched. Effects of reactor operating conditions, saltingout phenomenon and halophilic characteristics on membrane fouling was reaserchedand the experiment results shown that:Effects of operation conditions of two kinds of MBR reactor on membranepollution were similar. When useingcontinuous aerationThe membrane foulingwas lightest, and in the test range, with increasing of t, UGrand TMP, KVdecreased atfirst and then increased, and t, UGrandTMP had optimal values; fouling rate of aerobicbiofilm-membrane reactor membrane was less than anaerobic+aerobic biofilmmembrane reactor, that was to say, it was more advantageous to arrange the membranecomponent in the biofilm. Research on Effects of salting-out phenomenon found: salt particle size wassmaller, and had strong adhesion ability, which would plug the pore, or adhere on themembrane surface. Thus can aggravate membrane fouling and reduce the degree ofrecovery of membrane flux after cleaning.Study on influence of Halophilic characteristics on the membrane fouling found: Inthe7%salinity and10%salinity microbial systems, halophilic bacteria was dominatedby Bacillus and coccus, which cauled sludge floc smaller, and more loose. Sludge flocwouled plug the pore, or adhere to the surface of the diaphragm forming gel layer.②Operating conditions of the Anaerobic+aerobic biofilm membrane reactortreating7%salinity mustard tuber wastewater was optimize by response surfacemethodology. And the the treatment efficiency of it under this operating conditions wasresearched.The optimal conditions were as follows: t=3min, UGr=10m3m-2h-1, TMP=5KPa andcorresponding predicted KVvalue was7.87E+10. KVvalue obtained in the validationexperiments was7.86E+10±2.9E+9, which was close to the predicted value.Treatment efficiency study found: when reactor membrane number was less than2,the effluent can meet the "integrated wastewater discharge standard"(GB8978-1996)three level, and the reactor influent load was less than1.7KgCOD/（m3.d）, and theremoval rate of COD, NH4+-N, TN, souble phosphate and SS was more than90%,88%,56%,29%and97%respectively.③Operating conditions of the aerobic biofilm membrane reactor treating7%salinity mustard tuber wastewater was optimize by response surface methodology. Andthe the treatment efficiency of it under this operating conditions was researched.The optimal conditions were as follows: t=1min, UGr=12m3m-2h-1, TMP=20KPaand corresponding predicted KVvalue was7.42E+9. KV value obtained in the validationexperiments was7.42E+9±3.1E+8, which was close to the predicted value.Treatment efficiency study found: when reactor membrane number was less than2,the effluent can meet the "integrated wastewater discharge standard"(GB8978-1996)three level, and the reactor influent load was less than2.6KgCOD/（m3.d）, and theremoval rate of COD, NH4+-N, TN, souble phosphate and SS was more than86%,92%,50%,27%and97%respectively.④Oerating conditions of the Anaerobic+aerobic biofilm membrane reactortreating10%salinity mustard tuber wastewater was optimize by response surfacemethodology. And the the treatment efficiency of it under this operating conditions was researched.The optimal conditions were as follows: t=4min, UGr=14.6m3m-2h-1, TMP=19KPaand corresponding predicted KVvalue was2.07E+11. KVvalue obtained in thevalidation experiments was1.87E+11±1.9E+10, which was close to the predictedvalue.Treatment efficiency study found: when reactor membrane number was less than2,the effluent can meet the "integrated wastewater discharge standard"(GB8978-1996)three level, and the reactor influent load was less than1.9KgCOD/（m3.d）, and theremoval rate of COD, NH4+-N, TN, souble phosphate and SS was more than90%,92%,61%,30%and98%respectively.⑤Operating conditions of the aerobic biofilm membrane reactor treating10%salinity mustard tuber wastewater was optimize by response surface methodology. Andthe the treatment efficiency of it under this operating conditions was researched.The optimal conditions were as follows: t=3min, UGr=9m3m-2h-1, TMP=12KPaand corresponding predicted KVvalue was1.05E+10. KV value obtained in thevalidation experiments was1.07E+10±2.4E+9, which was close to the predicted value.Treatment efficiency study found: when reactor membrane number was less than2,the effluent can meet the "integrated wastewater discharge standard"(GB8978-1996)three level, and the reactor influent load was less than1.7KgCOD/（m3.d）, and theremoval rate of COD, NH4+-N, TN, souble phosphate and SS was more than90%,91%,58%,29%and98%respectively.The research achievements of the efficiency and the control of membrane foulingof treating mustard tuber wastewater by MBR Reactor would provide both a newtechnical route for the treatment of mustard tuber wastewater with high concentration ofsalt, and would also provide scientific basis for spread and practice of treating mustardtuber wastewater by Mixed MBR Reactor, which would be of important realisticsignificance. |
