| Membrane bioreactor (MBR) is an effective process for wastewater treatment.It has a lot of advantages over conventional wastewater treatment processes.However, membrane fouling is still a bottleneck that hinder MBR’s wild application.In order to solve this problem, a lot of technology appeared, in all of thesetechnology, Forward osmosis (FO) gain more attention,which is a process thatwater path through the membrane and diffuse to the high concentrated salt solution,combined the FO and MBR in a system,a new technology appeared—forwardosmosis membrane bioreactor (OMBR). In this work, focused on the research ofmembrane fouling and wastewater treatment efficiency.In this research, NaCl was used as the draw solution and after13days operation,we find that most of the microorganism is death, besides, Na+，Ca2+，Mg2+，K+andphosphate are accumulated in the bioreactor, based on these problems, we find twosolutions,one is removing the wastewater when the activity of the microorganism isdecreasing, the other is removing the wastewater everyday and make sure a balancethat removing salt is equivalent to the salt which diffuse to the bioreactor. A lot ofresearching job,including membrane fouling，wastewater treatment efficiency andreduction of sludge were carried out based on the two methods.OMBR has a better reduction of sludge over convention process, under thecomprehensive effect of metabolic balance and uncoupling of NaCl, during theoperation time, the sludge concentration can remain between2700mg/L to3000mg/L.It also has a good wastewater treatment efficiency, P can’t be checkedout and has a TOC removal of97.79%～98.64%and the effluent has a low ammonianitrogen which is less than3mg/L.During the process, water flux and the conductivity of the bioreactor weretested, we find that the specific reverse salt flux (or the ratio of the reverse salt fluxover water flux) was independent of the draw solution concentration, the specificreverse is1.04～1.2g/L. We also studied the change of SMP，LB-EPS，TB-EPS，sludge activity and sludge size during the operation time. FTIR-ATR was used toilluminate the fouled membrane and find that the major organic fouling were proteinand carbon hydration, through the SEM and EDX analysis find that the majorscaling were Si，Fe，Ca and Al.In order to analysis the fouling propensity of sludge property, the same sludge but different concentration and the same concentration but different sludge werecarried out in the same condition. The results showed that the flux decreasing as thesludge concentration increasing; As different sludge has different SMP, LB-EPS andTB-EPS concentration, the fouling propensity is discrepancy,as the increasing ofSMP, LB-EPS and TB-EPS concentration, the fouling is more serious and result in alow flux,at the same time,as the increasing of sludge viscosity and sludge size,theflux is decreasing.Alginate and BSA were used to represent carbon hydration and proteinrespectively to investigate the fouling propensity of carbon hydration and protein,the conclusion showed that BSA has a low fouling propensity but alginate has aserious fouling propensity, especially when the existence of Ca2+,the alginate canreact with Ca2+and result in more severe fouling. |
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