## Permeate
### Membrane-Based MFCs and Membrane bioreactor-Microbial Fuel Cells
Here, the MFC was functioning as a biosensor to monitor the COD in actual time. The combination of individual modules was used to attain contaminated water treatment and energy retrieval [26]. The MFC-MBR combination also helped in reducing the biofouling. This was achieved by merging a hollow fiber-membrane-based bioreactor with an MFC. The anodic chamber was an anaerobic compartment that was absorbed into the MBR, while the aerobic chamber of the MBR was used as the cathodic compartment, and in between these compartments [24], the module of the hollow fiber sheath was mounted. The introduction of an electrical field between both the electrodes improves the bacterial movement, which further increases the efficiency and superiority of the wastewater treatment. The electric field also helps in reducing membrane fouling by changing the properties of the sludge and impedes the adhering of negatively charged foulants to the membrane. A system assembled from the integration of an MFC with an electronic MBR (EMBR) was reported. In this setup, the cost was reduced by replacing the expensive proton exchange membrane (PEM) with a quartz silt compartment [33]. The bioelectricity produced in the EMBR was used to successfully hamper the membrane fouling. The electrolysis procedure was magnificently merged with the MFC for a broad spectrum of applications, such as methyl-red-contaminated water and algal pollution management [35]. The electrolysis pretreatment positively enhanced the MBR degradability and removal of chlorophyll a in these systems. Another successful integration was achieved, which was composed of an MFC and hydrogen bioreactors. Here, the effluent from the hydrogen bioreactor was used as an influent in the MFC for the production of energy and the treatment of sewage water [36]. It was detected that the H\({}_{2}\) yield was inversely proportional to the organic loading rate (OLR), with the maximum value of hydrogen production reached (2.72 mol H\({}_{2}\)/mol glucose) when the OLR was lowest (4 g/L d). It also gained the highest energy output of 4200 mW/m\({}^{3}\). By combining this method with solid-liquid separation, it was possible to produce value-added biochemicals [37]. Using this combined system, 214 L of methane and 37.7 L of hydrogen were obtained. An amount of 0.3 kg of solid particles/kg of the effluent was acquired using an efficient solid-liquid fractionation process. The solid mass obtained thus displayed features of fertilizers. The supernatant was utilized by the MFC for generating electricity; this supplied the energy demands of the solid-liquid separation and reduced the organic content of the wastewater. Along with the improved wastewater treatment, the MFC-MBR-integrated setup also reduced membrane fouling. After studying this system for its efficiency, it was depicted that the fundamental elements that affect the generation of electricity were the features of the sludge and the aeration in the cathodic chamber [30]. The membrane filtration was carried out for 27 days in closed-circuit mode and 13-15 days in open-circuit mode [24]. The MFC-MBR setup used for methylene blue degradation achieved maximum antifouling by utilizing the ARS/PPy-modified cathode membrane. In comparison with the nonaltered steel mesh, the power density was amplified 31-37 times due to this modification. As mentioned in Table 1, a system was assembled to mitigate the membrane fouling while achieving efficient wastewater treatment termed the 'antibiofouling MFC-MBR' [28]. When an exterior resistance of 50 \(\Omega\) was applied, the power output obtained was 2.18 W/m\({}^{3}\). Sludge reformation was another technique used to reduce the membrane fouling in the MFC-MBR setup. A fluid bed membrane was installed in the MFC-MBR-integrated setup used for domestic primary effluent treatment. When this setup constantly functioned for 50 days with domestic contaminated water influent with 210 mg/L COD, it displayed improved effluent quality with relatively low consumption of energy. The COD removal was 92.5%, lowering it to 16 mg/L.