Submerged Membrane Bioreactor To Deal With High Salt Oily Wastewater

With the development of petrochemical industrial, the treatment of oily sewage have received a considerable research interest. Presently the traditional flow: oil removal— floatation process—biological treatment has generally been used to dispose the oil contaminated water. But it has some disadvanages that it may greatly consume power; inhibiting effect of high-salinity to microorganism may influence effluent quality and the effluent can not be reused. Therefore, it is widespreadly significant to seek for the treatment process of high-saline oily wastewater with effective feasibility, credible economy and convenient management.With respect to the characteristics of high-saline oily wastewater, submerged membrane bioreactor was adopted, which studied the operating pressure affecting membrane flux; the effect of the reactor at different HRT and turbidity removal by MBR, characteristics of sludge; the mechanism and mitigating measure of membrane fouling; economic analysis.The experiment results showed that: in the condition recommended by this paper, removal efficiencies of COD and oil by MBR was more than 90% when HRT was 4, 6, 8h, respectively. Hence reaching primary discharged wastewater quality, which obviously excel the traditional biological process. Removal effect had not apparently advantage in the long HRT, which indicated that the long HRT was unfit for treating this kind of wastewater. Removal efficiencies of turbidity was among 96.0 % ~ 99.5 % , which was equal approximately to entire removal. MLSS concentration was higher than general activated sludge process while the former's MLVSS/MLSS is among 0.40—0.53 less than that of the later (0.75 for municipal sewage) . However, due to the high MLSS concentration in MBR, basing on integral effect, the former's sludge activity of unit volume is evidently higher than that of the later. When volume loading waved among 0.97~5.29kgCOD/m~3 ? d and sludge loading fluctuated among 0.13~0.55kgCOD/kgMLSS ? d, high removal rate was obtained. According to aboving conclusions, operating MBR under high volume loading and low sludge loading result in the excellent ability of MBR to resist shock loading.In addition to the mechanism of membrane fouling, the mitigating measure was also put forward.The means to clean the membrane module is water coupled with chemical cleaning as followed : after the sludge sorbed on the surface of membrane module is washedby water, it was marinated in 0.2 % NaClO for 6h, hence the membrane flux can be nearly recovered.In the term of economic analysis, MBR process to high-saline oily wastewater is feasible on economy, which simultaneously have predominance on technique, management, investment, area and treatment cost.