Research Scholar, Indian Institute of Technology Kharagpur
Wastewater treatment along with bioenergy recovery by hybrid microbial fuel cell-membrane bioreactor
A considerable proportion of world’s energy demand is being supplied by fossil fuels till now, which contributes significantly to the global warming. Burning of fossil fuels to provide energy in terms of heat or power for operating the existing wastewater treatment technologies, which is being followed by most of the industries or domestic enterprises, must be avoided to reduce its harmful influence on the environment. Considering the aforesaid reasons, innovative technology of simultaneous bio-energy recovery and wastewater treatment are a topic of current interest in scientific discussions. Out of them, Microbial fuel cell (MFC) is a promising technology for wastewater treatment and bio-energy recovery. MFC is a bio-electrochemical device that allows electrochemical energy production by breaking the chemical bonds of organic compounds into electrical energy through catalytic reactions of microorganisms under anaerobic conditions. MFC comprises anode, covered with electrophilic biofilm that can typically oxidize organic matter present in the wastewater under anoxic condition. This process extends bio-electricity generation combined with simultaneous treatment of wastewater in anodic chamber. Whereas, Membrane bioreactor (MBR) is a suspended growth process, where biodegradation of organic matter present in the wastewater is combined with microfiltration (MF) or ultrafiltration (UF) unit. The latter is typically used in lieu of secondary sedimentation tank used in conventional activated sludge process (ASP). However to achieve its practical application, still many technical and scaling up issues were required to be addressed for both the individual system MFC and MBR. So, I am introducing MFC-MBR hybrid system by different process and structural modifications to enhance the wastewater treatment efficiency as well as bio-energy recovery from the system. This technology is also adding the value by its small footstep and applicability in large scale applications like municipality or industry wastewater stream purification with subsequent energy recovery.
Abstract: Microbial fuel cell (MFC) presents a novel method for simultaneous energy recovery and wastewater treatment. In this study, a bio-cathode MFC with tubular membrane assembly was integrated to construct a MFC-TMBR system, which combined the advantages of each individual module. To examine the feasibility of MFC-TMBR integrated process, both electricity generation and wastewater treatment were investigated. Maximum voltage output of 0.8 V and maximum power density of 0.040 W/m(2) were obtained in the 30th day of operation. The MFC-TMBR system achieved organic removal of 94%, as well as the ammonia nitrogen removal of more than 80%. Membrane fouling mitigation was realized using cross-flow filtration with tubular membrane in the MFC-TMBR, without any physical cleaning during the 30-day operation. Lower MLSS concentration and higher DO could potentially support this system. Low-cost materials were adopted for reactor construction. The results demonstrate that this system is an energy-efficient and cost-effective approach for wastewater treatment.
Pub.: 09 Oct '13, Pinned: 28 Jul '17
Abstract: A hollow-fiber membrane bioreactor was integrated with a microbial fuel cell to develop a novel system of MFC-MBR based on the utilization of electricity recovered by the MFC for wastewater treatment improvement and membrane fouling mitigation in the MBR. In this system, a maximum power density of 2.18 W/m(3) and an average voltage output of 0.15 V were achieved at an external resistance of 50 Ω. The removal efficiencies of COD, ammonia nitrogen ( [Formula: see text] ) and total nitrogen (TN) in the MFC-MBR were improved by 4.4%, 1.2% and 10.3%, respectively. It is worth noting that, in addition to reducing the deposition of sludge on the membrane surface by the electric field force, the MFC-MBR also alleviated the membrane fouling by sludge modification. Compared with the control MBR (C-MBR), less loosely bound extracellular polymeric substances (LB-EPS), lower SMPp/SMPc ratio, more homogenized sludge flocs and less filamentous bacteria were obtained in the MFC-MBR, which improved the dewaterability and filterability of the sludge. The cake layer on the membrane formed by the modified sludge was more porous with lower compressibility, significantly enhancing the membrane filterability. A proof of concept of an MFC-MBR was provided and shown to be effective in membrane fouling mitigation with efficient wastewater treatment and energy recovery, demonstrating the feasibility of the minute electricity generated by the MFC for membrane fouling alleviation in the MBR.
Pub.: 15 Sep '14, Pinned: 28 Jul '17
Abstract: A novel overflow-type electrochemical membrane bioreactor (EMBR) without ion exchange membrane, was developed for wastewater treatment and utilized electricity recovered by microbial fuel cell (MFC) for membrane fouling mitigation in membrane bioreactor (MBR). The maximum power density of 629mW/m(3) or 7.18mW/m(2) was obtained. The removal efficiencies of chemical oxygen demand, ammonia nitrogen and total nitrogen under appropriate ranges of hydraulic retention times (16.9-8.5h) were 92.6±5.4%, 96.5±2.8% and 73.9±9.7%, respectively. Sequencing showed electrochemically active bacteria Lactococcus, Bacillus and Saprospiraceae_uncultured were abundant in the biofilm. Compared with a conventional MBR, five significant effects of the MFC integration on the sludge properties, including particle zeta potential decrease, particle size distribution macroaggregation, soluble microbial products and extracellular polymeric substances reduction and SMPP/SMPC ratio increase, were achieved in this system, leading to membrane fouling mitigation. This system shows great promise for practical wastewater treatment application.
Pub.: 25 Aug '15, Pinned: 28 Jul '17
Abstract: In this study, membrane bioreactor (MBR) and microbial fuel cell (MFC) was coupled for wastewater treatment using a polyvinylidene fluoride (PVDF) coated carbon fiber cloth as cathode membrane. To generate more power and mitigate membrane fouling, granular activated carbon (GAC) was added as a dynamic layer on cathode membrane. With or without FeOOH/TiO2 doping on GAC, 2 e-or 4 e- oxygen reduction reactions (ORRs) took place. The maximum power density reached 5.1 W m-3 via 4e- ORR, practically the highest compared to similar MBR/MFC coupled systems. The removal of COD and NH4+-N was 90% and 80%, respectively. With FeOOH/TiO2/GAC, hydrogen peroxide (H2O2) was formed via 2 e- ORR, at 0.13 mg L-1 in effluent. Oxidative removal of a model pollutant tetracycline hydrochloride was 90% by reactive oxidizing species such as •OH. This is the first report of H2O2 synthesis using doped GAC as expanded cathode in coupled bio-electrochemical MBR/MFC system. Compared to other electrochemical systems, our bio-electrochemical system was more energy-saving and environmental-friendly in wastewater treatment.
Pub.: 01 Nov '16, Pinned: 28 Jul '17