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Anaerobic membrane bioreactors (AnMBRs) are formed through the combination of anaerobic digestion and membrane technology. The upgraded technology separates SRT from HRT in the anaerobic digester, shortening the treatment period, reducing the digester's volume and improving effluent quality. Furthermore, AnMBRs have a strong tolerance for the existing forms of objects and can handle liquids, high-solid materials and gases. Up to now, AnMBRs have been utilized in the treatment of various types of industrial and municipal wastewater, organic solid waste and also biogas upgrading, and they have achieved excellent performance. However, there are few studies which have discussed their multiple utilization, especially following the flow of wastewater treatment. This study summarizes the application of AnMBRs in their diverse roles in the municipal wastewater treatment process. The discussion revolves around energy generation and the fouling issue of AnMBRs in the treatment of municipal wastewater, the digestion of sewage sludge generated in conventional municipal wastewater treatment and the upgrading of biogas after anaerobic digestion. In addition to controlling operating parameters, strategies used to improve the treatment effectiveness are also introduced. Lastly, online methods for preventing membrane fouling, which is the main operational obstacle to AnMBRs' wider spread, are also discussed. This review aims to provide a fresh perspective on how AnMBRs are utilized in waste treatment. [ABSTRACT FROM AUTHOR]

Anaerobic membrane bioreactors (AnMBRs) require biogas recycling to stir the mixed liquid and flush particles away from the membrane surfaces for stable operation. With the fixed gas cycling rate, gas diffuser configuration is an important factor that affects stirring and flushing performance. This study investigated the effect of different outlet diameters on biogas diffusers in AnMBR by using computational fluid dynamics (CFD) to analyze gas–liquid flow in a numerical model constructed based on an experimental AnMBR. According to the CFD results, as the outlet diameter increased from 2.5 to 5.0 mm, the average velocity increased from 0.15 to 0.31 m/s and the average wall shear stress (WSS) increased from 0.21 to 1.10 Pa on the membrane surface. The increase in gas velocity enhances the stirring effect, and the increase in WSS improves the flushing performance. However, when it was further increased to 10.0 mm, the average velocity and average WSS was 0.27 m/s and 0.22 Pa, respectively, indicating that too large an outlet diameter leads to a concentrated gas distribution, which reduces the performance of stirring and flushing. Furthermore, these results provide a basis for optimizing diffuser configuration, which is significant for promoting the practical application of AnMBR in wastewater treatment. [ABSTRACT FROM AUTHOR]

Developing low-carbon advanced processes for sustainable wastewater treatment is of great importance to increase bioenergy recovery and to reduce the greenhouse gas effect. In this study, the influence of adding 25 g/L of granular activated carbon (GAC) on the process performance was studied with a lab-scale GAC amended anaerobic dynamic membrane (G-AnDMBR) used to treat real domestic wastewater, which was compared to a control bioreactor without the GAC addition (C-AnDMBR). Due to the initial adsorption effect of GAC and the high microbial activity of the attached biomass of GAC, the G-AnDMBR achieved a better removal of the total chemical oxygen demand (TCOD) and turbidity compared to the C-AnDMBR, with the average removal rate increasing from 82.1% to 86.7% and from 88.7% to 93.2%. The gaseous methane production increased from 0.08 ± 0.05 to 0.14 ± 0.04 L/d, and the total methane production rate was enhanced from 0.21 ± 0.11 to 0.23 ± 0.09 LCH4/gCOD. Thus, the treatment performance of the G-AnDMBR was superior to that of the C-AnDMBR, and the addition of GAC could improve the effluent quality during the initial dynamic membrane formation process. In addition, the buffering effect of GAC made the G-AnDMBR maintain a relatively stable solution environment. The G-AnDMBR showed a transmembrane pressure (TMP) increasing rate of 0.045 kPa/d, which was obviously lower than that of the C-AnDMBR (0.057 kPa/d) because the nonfluidized GAC could trap fine sludge particles and adsorb soluble extracellular polymer substances (SEPSs), thus inhibiting the over formation of the dynamic membrane layer. A microbial property analysis indicated that GAC induced a change in the microbial community and enhanced the gene abundance of type IV pili and that it also potentially accelerated the direct interspecific electron transfer (DIET) among syntrophic bacteria and methanogens by enriching specific functional microorganisms. The results indicated that the integration of GAC and the AnDMBR process can be a cost-effective and promising alternative for domestic wastewater treatment and bioenergy recovery. [ABSTRACT FROM AUTHOR]