Microbial Fuel Cell Membrane Bioreactor Research Articles

A novel integrated microbial fuel cell-membrane bioreactor (MFC-MBR) for controlling the spread of antibiotic and antibiotic resistance genes while simultaneously alleviating membrane fouling

The dissemination of antibiotics and antibiotic resistance genes (ARGs) in the environment can potentially pose risks to ecosystems and human health. Herein, a novel microbial fuel cell and membrane bioreactor (MFC-MBR) integrated system characterized by internal reflux of sludge mixtures was proposed to reduce antibiotics, control the spread risk of antibiotic resistance genes (ARGs), and simultaneously alleviate membrane fouling. The bioelectricity production was distinctly promoted with increasing return flow ratios under sulfamethoxazole (SMX) addition. Besides, reactors characterized by higher return flow ratios achieved a relatively elevated degradation rate of SMX, attributed to the enhanced microbial activities through electrical stimulation. Importantly, the absolute abundance of intI1, sul1 and sul3 significantly decreased in the effluent of reactors characterized by higher return flow ratios. The value of zeta potential and particle size of sludge flocs subsequently increased and the content of membrane foulants dropped with the increasing return flow ratios. Moreover, MFC-MBRs characterized by higher return flow ratios were enriched in antibiotic degrading bacteria (Firmicutes, Thauera) and electrochemically active bacteria (Proteobacteria, Bacteroidota). Therefore, this study provided a theoretical basis for reducing the spread of antibiotics and ARGs while simultaneously alleviating fouling, achieving the best of both worlds, through the novel MFC-MBR integrated system.

In-depth insight on microbial electrochemical systems coupled with membrane bioreactors for performance enhancement: a review.

A conventional activated sludge (CAS) system has traditionally been used for secondary treatment in wastewater treatment plants. Due to the high cost of aeration and the problem of sludge treatment, researchers are developing alternatives to the CAS system. A membrane bioreactor (MBR) is a technology with higher solid-liquid separation efficiency. However, the use of MBR is limited due to inevitable membrane fouling and high energy consumption. Membrane fouling requires frequent cleaning, and MBR components must be replaced, which reduces membrane lifetime and operating costs. To overcome the limitations of the MBR system, a microbial fuel cell-membrane bioreactor (MFC-MBR) coupling system has attracted the interest of researchers. The design of the novel bioelectrochemical membrane reactor (BEMR) can effectively couple microbial degradation in the microbial electrochemical system (MES) and generate a microelectric field to reduce and alleviate membrane fouling in the MBR system. In addition, the coupling system combining an MES and an MBR can improve the efficiency of COD and ammonium removal while generating electricity to balance the energy consumption of the system. However, several obstacles must be overcome before the MFC-MBR coupling system can be commercialised. The aim of this study is to provide critical studies of the MBR, MES and MFC-MBR coupling system for wastewater treatment. This paper begins with a critical discussion of the unresolved MBR fouling problem. There are detailed past and current studies of the MES-MBR coupling system with comparison of performances of the system. Finally, the challenges faced in developing the coupling system on a large scale were discussed.

Alleviating membrane fouling by enhanced bioelectricity generation via internal reflux of sludge mixed liquor in microbial fuel cell-membrane bioreactor (MFC-MBR) coupling system

The in-situ utilization of sludge mixed liquor was innovatively applied in microbial fuel cell and membrane bioreactor (MFC-MBR) coupling system. MFC-MBR coupling systems with different return flow ratio were designed to investigate the effects of return flow on bioelectricity generation and subsequently membrane fouling mitigation. The results indicated that bioelectricity generation was largely enhanced with the increasing return flow ratio. Furthermore, the slow growth of the transmembrane pressure (TMP) was found in MFC-MBR coupling systems that with return flow ratios of 0.50 and 0.75, respectively (0.66 kPa/d and 0.57 kPa/d). It was evident from the declined absolute value of zeta potential in systems with return flow ratio, which enlarged the flocculation of sludge particles and was in accordance with the particle size distribution. The increase rate of soluble microbial products (SMP) and extracellular polymeric substances (EPS) were also significantly dropped while the ratio of protein to polysaccharide in SMP and EPS rose in MFC-MBR coupling systems with return flow. Importantly, Bacteroidetes and Chlorobiaceae were more abundant in MFC-MBR coupling systems with higher return flow ratios. Thus, MFC-MBR coupling system with internal reflux of sludge mixed liquor was effective in improving bioelectricity generation and minimizing membrane fouling.

Two-stage microbial fuel cell (MFC) and membrane bioreactor (MBR) system for enhancing wastewater treatment and resource recovery based on MFC as a biosensor.

Lack of process control between the two stages of a combined microbial fuel cell-membrane bioreactor (MFC-MBR) system limits its application in wastewater treatment due to membrane fouling and high energy consumption. In this study, a two-stage MFC-MBR integrated system was established to investigate the impact of incorporating process control on petroleum refinery wastewater treatment. The results showed that chemical oxygen demand (COD) removal exhibits a linear relationship with the MFC voltage output (R2=0.9821); therefore, the MFC was used as a biosensor to control the combined system. The removal efficiencies of COD, ammonium nitrogen (NH4+-N), and total nitrogen (TN) were 96.3%, 92.4%, and 86.6%, respectively, in the MFC-MBR biosensor, whereas those in the control system were 74.7%, 71.2%, and 64.7% respectively. Furthermore，using the biosensor control system yielded a 50% reduction in the transmembrane pressure (1.01kPa day-1) and decreased membrane fouling in wastewater treatment. The maximum energy recovery of the biosensor system (0.00258kWh m-3) was five times higher than that of the control system, as determined by calculating the mass balance of the system. Thus, this study indicates that using the MFC as a biosensor for process control in an MFC-MBR system can improve overall system performance.

Microbial Fuel Cell Membrane Bioreactor in Wastewater Treatment, Electricity Generation and Fouling Mitigation

AbstractMembrane bioreactors (MBR) have gained much attention due to their ability to achieve higher treatment efficiency. However, high external energy consumption in aeration for membrane fouling mitigation has been limiting their application. Microbial fuel cells (MFC) can ideally extract energy from wastewater in the form of electricity and reduce membrane fouling. Thus, the use of MFC‐MBR is rapidly expanding. However, the MFC‐MBR design and operation is not fully mature and further research is needed to optimize the process efficiency and enhance the applicability. This review gives an overview of recent studies on the performances of MFC‐MBR systems, regarding the design and configuration of the integrated system, irrespective of whether optimization was done or not in the operating system.

Improved Wastewater Treatment by Combined System of Microbial Fuel Cell with Activated Carbon/TiO2 Cathode Catalyst and Membrane Bioreactor

A two-stage continuous process was developed for treating medium-strength wastewater combining microbial fuel cell (MFC) using activated carbon (AC)/TiO2 composite as cathode catalyst and submerged membrane bioreactor (MBR). Synthetic wastewater, having total chemical oxygen demand (COD) of around 3 g/L, was introduced first in the anodic chamber of MFC in a continuous mode of operation followed by aerobic MBR. Submerged hollow-fibre ultra-filtration membrane assembly was attached to draw permeate from MBR. The electrical performance of MFC was evaluated by polarisation, which showed a maximum volumetric power density of 1.02 W/m3 with much lower whole-cell internal resistance of 10 Ω. The coulombic efficiency of MFC was estimated to be 0.31%, demonstrating AC/TiO2 composite as a promising cathode catalyst for applications in MFC. The permeate of MFC–MBR system showed 98.3 ± 0.3% and 81.9 ± 1.8% of COD and total Kjeldahl nitrogen removal efficiency, respectively, producing permeate with total suspended solids concentration of less than 5 mg/L. Thus, a two-stage reliable process for treatment of wastewater is demonstrated using integrated MFC–MBR for generating high-quality recyclable effluent and facilitating recovery of bio-electricity.

Microbial Fuel Cell-Membrane Bioreactor Integrated System for Wastewater Treatment and Bioelectricity Production: Overview

AbstractEconomic development and the related increase in global energy demands have created pressure on the supply of energy resources. To promote sustainable development, a safe and renewable ener...

TiO2/Activated carbon photo cathode catalyst exposed to ultraviolet radiation to enhance the efficacy of integrated microbial fuel cell-membrane bioreactor

Two integrated microbial fuel cell-membrane bioreactor (MFC-MBR) were developed to treat medium-strength wastewater with simultaneous power generation. Both the systems were operated with photo-sensitized cathode (with TiO2-Activated carbon) with one irradiated by UV-A light (MMT-UV), while the other was not in direct contact with any light sensitization (MMT). In polarization, MMT-UV exhibited higher maximum power density of 494 mW m−2 as compared to MMT (239 mW m−2). Normalized energy recovery was also estimated to be 0.122 kWh m−3 for MMT-UV and 0.058 kWh m−3 for MMT. On the other hand, overall chemical oxygen demand and total Kjeldahl nitrogen removal efficiency were almost similar and high enough ( ̴ 95% and 86–90%, respectively) for these type of two-stage wastewater treatment systems with very less footprint. Hence, the integrated MFC-MBR with TiO2-Activated carbon as cathode-catalyst in presence of UV showed excellent treatability of wastewater with simultaneous bioelectricity generation to reduce the overall energy demand.

Impacts of energy distribution and electric field on membrane fouling control in microbial fuel cell-membrane bioreactor (MFC-MBR) coupling system

To investigate the influence of energy allocation on membrane fouling, three coupling systems at different concentrations of mixed liquid suspended solids (MLSS) and a control system without microbial fuel cell (MFC) were established. The results show that MFC acted negative effect in low-loading stage (0.59 kg-COD·m−3·d−1), while high MLSS acted active effect on organics degradation in high-loading stage (2.00 kg-COD·m−3·d−1), and electric field could be a positive factor with sufficient energy. Besides, membrane filtration experiments in the electric field with microbial contaminants indicate that soluble microbial products (SMP) and loosely bound extracellular polymeric substances (LB-EPS) had greater tendencies to cause irreversible membrane fouling. SMP and the residual cell liquid (Cell) were more susceptible than extracellular polymeric substances (EPS), demonstrating that the irreversible fouling was reduced mainly due to SMP decrease in the electric field.

Evaluation of energy-distribution of a hybrid microbial fuel cell–membrane bioreactor (MFC–MBR) for cost-effective wastewater treatment

A low-cost hybrid system integrating a membrane-less microbial fuel cell (MFC) with an anoxic/oxic membrane bioreactor (MBR) was studied for fouling mitigation. The appended electric field in the MBR was supplied by the MFC with continuous flow. Supernatant from an anaerobic reactor with low dissolved oxygen was used as feed to the MFC in order to enhance its performance compared with that fed with synthetic wastewater. The voltage output of MFC maintained at 0.52±0.02V with 1000Ω resister. The electric field intensity could reach to 0.114Vcm−1. Compared with the conventional MBR (CMBR), the contents rather than the components of foulants on the cake layer of fouled MFC–MBR system was significantly reduced. Although only 0.5% of the feed COD was translated into electricity and applied to MBR, the hybrid system showed great feasibility without additional consumption but extracting energy from waste water and significantly enhancing the membrane filterability.

A novel approach to recycle bacterial culture waste for fermentation reuse via a microbial fuel cell-membrane bioreactor system.

Biochemical production processes require water and nutrient resources for culture media preparation, but aqueous waste is generated after the target products are extracted. In this study, culture waste (including cells) produced from a lab-scale fermenter was fed into a microbial fuel cell-membrane bioreactor (MFC-MBR) system. Electrical energy was generated via the interaction between the microbial consortia and the solid electrode in the MFC. The treated wastewater was reclaimed in this process which was reused as a solvent and a nutrient source in subsequent fermentation. Polarization testing showed that the MFC produced a maximum current density of 37.53 Am(-3) with a maximum power density of 5.49Wm(-3). The MFC was able to generate 0.04 kWh of energy per cubic meter of culture waste treated. The lab-scale fermenters containing pure cultures of an engineered Pseudomonas spp. were used to generate 2-pyrone-4,6-dicarboxylic acid (PDC), a high value platform chemical. When the MFC-MBR-treated wastewater was used for the fermenter culture medium, a specific bacterial growth rate of 1.00±0.05h(-1) was obtained with a PDC production rate of 708.11±64.70mg PDC L(-1)h(-1). Comparable values for controls using pure water were 0.95±0.06h(-1) and 621.01±22.09mg PDC L(-1)h(-1) (P>0.05), respectively. The results provide insight on a new approach for more sustainable bio-material production while at the same time generating energy, and suggest that the treated wastewater can be used as a solvent and a nutrient source for the fermentation production of high value platform chemicals.

A Hybrid Microbial Fuel Cell Membrane Bioreactor with a Conductive Ultrafiltration Membrane Biocathode for Wastewater Treatment

A new hybrid, air-biocathode microbial fuel cell-membrane bioreactor (MFC-MBR) system was developed to achieve simultaneous wastewater treatment and ultrafiltration to produce water for direct reclamation. The combined advantages of this system were achieved by using an electrically conductive ultrafiltration membrane as both the cathode and the membrane for wastewater filtration. The MFC-MBR used an air-biocathode, and it was shown to have good performance relative to an otherwise identical cathode containing a platinum catalyst. With 0.1 mm prefiltered domestic wastewater as the feed, the maximum power density was 0.38 W/m(2) (6.8 W/m(3)) with the biocathode, compared to 0.82 W/m(2) (14.5 W/m(3)) using the platinum cathode. The permeate quality from the biocathode reactor was comparable to that of a conventional MBR, with removals of 97% of the soluble chemical oxygen demand, 97% NH3-N, and 91% of total bacteria (based on flow cytometry). The permeate turbidity was <0.1 nephelometric turbidity units. These results show that a biocathode MFC-MBR system can achieve high levels of wastewater treatment with a low energy input due to the lack of a need for wastewater aeration.

A microbial fuel cell–membrane bioreactor integrated system for cost-effective wastewater treatment

Microbial fuel cell (MFC) and membrane bioreactor (MBR) are both promising technologies for wastewater treatment, but both with limitations. In this study, a novel MFC–MBR integrated system, which combines the advantages of the individual systems, was proposed for simultaneous wastewater treatment and energy recovery. The system favored a better utilization of the oxygen in the aeration tank of MBR by the MFC biocathode, and enabled a high effluent quality. Continuous and stable electricity generation, with the average current of 1.9±0.4mA, was achieved over a long period of about 40days. The maximum power density reached 6.0Wm−3. Moreover, low-cost materials were used for the reactor construction. This integrated system shows great promise for practical wastewater treatment application.