Research On The Performance And Membrane Fouling Characteristics Of AF-MBR For Mariculture Wastewater Treatment

Currently,the development of marine aquaculture has caused large amount of mariculture wastewater emission to adjacent sea,and caused serious ecological problems.Also,it has many difficulties in the treatment fo mariculture wastewater because its high salinity and high ammonia nitrogen concentration.And membrane bioreactor(MBR)as an efficient means of biological treatment,has the characteristics of high biodegradation and good effluent quality.Therefore,it has been widely applied in wastewater treatment field.In this research,we built an anoxic biofilter-MBR combined reaction system,polyporous suspended filler was added into the MBR in contrast with a single MBR.So,we researched the treatment efficiency for simulated mariculture wastewater and membrane fouing phenomenon of AF-MBR.In the study of the effect of AF-MBR on the treatment of simulated mariculture wastewater,Total Organic Carbon(TOC),phosphate and total nitrogen removal efficiency were used as indicators.The experimental results showed that the treatment effect was better when HRT was 8 h,the influent alkalinity was 500 mg/L and the ammonia nitrogen load is 50 mg/L,and the AF-MBR's effect was always better than that of the control MBR.By analyzing the concentration of ammonia nitrogen,nitrate nitrogen and nitrite nitrogen in the two reation systems,it was found that the main reaction in the control MBR is nitrification under aerobic conditions,while in the AF-MBR,the reflux between the anoxic biofilter and MBR led to a short-cut nitrification and denitrification.Through the analysis of the membrane fouling phenomenon of AF-MBR and the control MBR,it can be found that the membrane fouling of AF-MBR has been significantly relieved.Also,the concentration of SMP and EPS produced during the operation of AF-MBR was lower than that of the control MBR.This result was also consistent with the analysis of infrared and three-dimensional fluorescence spectra.At the same time,through the experiments of filtration characteristics and adsorption characteristics of SMP and EPS,we can found that the rate of reduction caused by SMP and EPS in control MBR was greater,and the protein and polysaccharide in SMP and EPS in control MBR were more easily adsorbed on the surface of the membrane and not easily removed during the operation of the reactor.Result of the filtration process simulation showed that SMP and EPS in AF-MBR was more consistent with the standard blocking model,while SMP and EPS in control MBR had better fitting degree to the cake filtration model and standard model.The surface correlation analysis revealed that the surface energy of SMP and EPS in AF-MBR was lower than that of control MBR,indicating that SMP and EPS of control MBR were more easier to deposite on the membrane surface.Through the above analysis,it can be found that the membrane fouling phenomenon of AF-MBR is better than the control MBR.