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Soluble microbial products (SMP) that persist in the effluent of membrane bioreactors (MBRs) impact not only discharge quality, but also the performance of advanced filtration processes. This study investigated the effect of SMP on the characteristics and fouling potential of a laboratory-scale MBR effluent. First, the domestic wastewater influent, mixed liquor supernatant, and effluent were assessed. Variations in specific ultraviolet adsorption (SUVA) and molecular weight distribution (MWD) confirmed the degradation of pollutants, generation of SMP, and permeation of SMP through the membrane. The effluent contained more carbohydrates than proteins, but the two species combined had minority contribution to the total organic load. Instead, humic acids were the most abundant as confirmed by excitation–emission matrix (EEM) fluorescence spectroscopy analysis. Second, the MBR effluent was subjected to crossflow ultrafiltration (UF). The UF membrane quickly lost 60% of its initial flux, and dramatic transformations in surface morphology and roughness occurred. It also had poor SMP removal efficiency, as most of the carbohydrates and humic acids were not rejected. More proteins were identified on the fouled membrane surface, suggesting that they have a significant role in UF membrane fouling formation.

In this study, the performance of sequencing batch reactor (SBR), aerobic membrane bioreactor (AMBR), anaerobic-oxic membrane bioreactor (AOMBR) and AOMBR/RO processes treating the synthetic textile dyeing wastewater (Reactive Black 5) was investigated and compared. After more than 2 year process operation, the average SS concentration for SBR, AMBR, AOMBR, and AOMBR/RO process effluent were 96, 0, 0, and 0 mg L−1, respectively. Furthermore, the COD of the above effluent were 133, 95, 37, and 38 mg L−1, respectively. It was found that the anaerobic tank of AOMBR and AOMBR/RO can lower the COD concentration. In addition, the BOD of the above effluent were 68, 3, 3, and 0 mg L−1, respectively. For this parameter, the membrane unit also showed an excellent performance. Finally, the true color of the above effluent were 548, 513, 196 and 32 ADMI, respectively, revealed that the anaerobic tank and RO unit could achieve higher color removal performance. This revealed that the processes containing membrane unit performed excellent efficiencies on SS and BOD removal. Additionally, the anaerobic tank can enhance the COD and true color removal, while the RO unit can further remove the true color. According the experiment result, all the processes containing membrane unit meet the Taiwan EPA effluent criteria, but only the AOMBR/RO process meets the water reclamation criteria for toilet flushing, landscaping, irrigation, sprinkling, and cooling water usage. This study also isolated higher decolorized performance microorganisms by using TGE, PDA and TGC mediums. Only 3 isolates performed more than 90% Reactive Black 5 degrading efficiencies by using both TGE and aerobic PDA mediums. On the contrary, no isolate was obtained by using anaerobic PDA mediums, implied that there is no strictly anaerobic fungi in the anaerobic tank. Furthermore, 18 isolates cultured from anaerobic TGC medium showed more than 90% Reactive Black 5 removal efficiency, revealed that the anaerobic tank did enhance the growth of the high decolorizedmicroorganisms, especially anaerobic bacteria.

This study is aimed using ozonation to remove the fouling that occurs on ultrafiltration membranes. Polyvinylidene fluoride (PVDF) was utilized for the membrane material. The tertiary effluent from industrial park wastewater plant was treated by an ultrafiltration membrane process. A bench-scale system was performed to evaluate the efficiency of fouling removed by an ozonation process. The results should be a valuable reference encouraging the recovery of tertiary effluent by the membrane process. The ozonation process was done via the direct continuous dosing of ozone into the influent. The ozone gas mass flow rate was 8.79 mg/min; the residual ozone concentration in the influent flow was maintained at about 4.02 mg/L throughout the test. It was demonstrated that without ozonation the permeate flux dropped to 60% after 1 h, but that with ozonation it could be maintained at 90% through the test. The SEM observations showed that much fouling that had clogged the membrane was effectively removed by ozonation. The mechanism of fouling removed was also illuminated by the IR analysis. It was observed that the ozone could oxidize and destroy the organic fouling, and the cross flow could flush away any loose fragments on the filtration cake.

Both the relationship between the flux and the fouling mechanism of ultrafiltration (UF) membrane and the effects of pretreatment before reverse osmosis (RO) process on the treatment of the effluent of industrial park wastewater treatment plant (IPWTP) were investigated to examine the application of membrane processes on the water reuse treatment. For the former, the flux data was first fitted to the Hermia model to give the implication of the fouling mechanism. Then, the fouling mechanism was further identified with the aid of the SEM morphology of membrane surfaces. For the latter, the changes of both water characteristics (turbidity, TOC, conductivity, particle size distribution, and organic solute molecular weight) and membrane properties (surface zeta potential and surface morphology) before and after the treatment of membrane processes were measured. It was found that the major blocking mechanisms of UF membrane process at initial and final stage were standard blocking of pore (causing from colloid materials) and cake blocking of pore (causing from suspended particles), respectively. On the other hand, it was concluded that the permeate from 1 μm/UF/RO process was suitable for the reuse of cooling water and low pressure boiler water.