Application of membrane bioreactor for sulfamethazine-contained wastewater treatment.

The presence of antibiotics in wastewater has been widely confirmed. Membrane bioreactor (MBR), as an efficient wastewater treatment technology, has attracted increasing interest in its ability to remove antibiotics in recent years. However, its long-term operation stability and the underlying mechanisms for antibiotics removal are still poorly understood. In this study, a hollow fiber MBR was used to treat low concentration sulfamethazine (SMZ) contained wastewater. The long-term effects of various SMZ concentrations on nutrients removal, SMZ degradation, and sludge characteristics were investigated. During the 244 days operation, the overall SMZ removal efficiency could reach 95.4 ± 4.5% under various SMZ concentrations and hydraulic retention times. The reactor exhibited high chemical oxygen demand and NH4+-N removal efficiencies, which reached 93.0% and 96.2%, respectively. A sludge concentration of 4.1 ± 0.3 g/L was maintained in the system without excess sludge discharge. The dosage of SMZ had obvious effect on sludge characteristics. The contents of extracellular polymeric substances (EPS) in MBR decreased after a long-term operation of the reactor under SMZ pressure. The low sludge concentration and the reduced EPS content were also beneficial for mitigating membrane fouling. Thus, this study provides a low-cost, efficient and simple approach to treat SMZ-contained wastewater.

Development of an energy-saving anaerobic hybrid membrane bioreactors for 2-chlorophenol-contained wastewater treatment.

A novel energy-saving anaerobic hybrid membrane bioreactor (AnHMBR) with mesh filter, which takes advantage of anaerobic membrane bioreactor and fixed-bed biofilm reactor, is developed for low-strength 2-chlorophenol (2-CP)-contained wastewater treatment. In this system, the anaerobic membrane bioreactor is stuffed with granular activated carbon to construct an anaerobic hybrid fixed-bed biofilm membrane bioreactor. The effluent turbidity from the AnHMBR system was low during most of the operation period, and the chemical oxygen demand and 2-CP removal efficiencies averaged 82.3% and 92.6%, respectively. Furthermore, a low membrane fouling rate was achieved during the operation. During the AnHMBR operation, the only energy consumption was for feed pump. And a low energy demand of 0.0045-0.0063kWhm(-3) was estimated under the current operation conditions. All these results demonstrated that this novel AnHMBR is a sustainable technology for treating 2-CP-contained wastewater.

In-situ utilization of generated electricity in an electrochemical membrane bioreactor to mitigate membrane fouling.

How to mitigate membrane fouling remains a critical challenge for widespread application of membrane bioreactors. Herein, an antifouling electrochemical membrane bioreactor (EMBR) was developed based on in-situ utilization of the generated electricity for fouling control. In this system, a maximum power density of 1.43 W/m(3) and a current density of 18.49 A/m(3) were obtained. The results demonstrate that the formed electric field reduced the deposition of sludge on membrane surface by enhancing the electrostatic repulsive force between them. The produced H2O2 at the cathode also contributed to the fouling mitigation by in-situ removing the membrane foulants. In addition, 93.7% chemical oxygen demand (COD) removal and 96.5% NH4(+)-N removal in average as well as a low effluent turbidity of below 2 NTU were achieved, indicating a good wastewater treatment performance of the EMBR. This work provides a proof-of-concept study of an antifouling MBR with high wastewater treatment efficiency and electricity recovery, and implies that electrochemical control might provide another promising avenue to in-situ suppress the membrane fouling in MBRs.

A novel electrochemical membrane bioreactor as a potential net energy producer for sustainable wastewater treatment.

One possible way to address both water and energy shortage issues, the two of major global challenges, is to recover energy and water resource from wastewater. Herein, a novel electrochemical membrane bioreactor (EMBR) was developed to recover energy from wastewater and meantime harvest clean water for reuse. With the help of the microorganisms in the biocatalysis and biodegradation process, net electricity could be recovered from a low-strength synthetic wastewater after estimating total energy consumption of this system. In addition, high-quality clean water was obtained for reuse. The results clearly demonstrate that, under the optimized operating conditions, it is possible to recover net energy from wastewater, while at the same time to harvest high-quality effluent for reuse with this novel wastewater treatment system.