The effects of wastewater types on power generation and phosphorus removal of microbial fuel cells (MFCs) with activated carbon (AC) cathodes (original) (raw)
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Catalysts, 2020
In this paper, the effect of cathode configuration on the performance of a membrane-less microbial fuel cell (MFC) was evaluated using three different arrangements: an activated carbon bed exposed to air (MFCE), a wetland immersed in an activated carbon bed (MFCW) and a cathode connected to an aeration tower featuring a water recirculation device (MFCT). To evaluate the MFC performance, the efficiency of the organic matter removal, the generated voltage, the power density and the internal resistance of the systems were properly assessed. The experimental results showed that while the COD removal efficiency was in all cases over 60% (after 40 days), the MFCT arrangement showed the best performance since the average removal value was 82%, compared to close to 70% for MFCE and MFCW. Statistical analysis of the COD removal efficiency confirmed that the performance of MCFT is substantially better than that of MFCE and MFCW. In regard to the other parameters surveyed, no significant influ...
Journal Of The Institution Of Engineers (india): Series A, 2019
A two-stage continuous process was developed for treating medium-strength wastewater combining microbial fuel cell (MFC) using activated carbon (AC)/ TiO 2 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/m 3 with much lower whole-cell internal resistance of 10 X. The coulombic efficiency of MFC was estimated to be 0.31%, demonstrating AC/TiO 2 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.
International Journal of Hydrogen Energy, 2011
A new type of microbial fuel cell (MFC), multi-anode/cathode MFC (termed as MAC MFC) containing 12 anodes/cathodes were developed to harvest electric power treating domestic wastewater. The power density of MAC MFCs increased from 300 to 380 mW/m 2 at the range of the organic loading rates (0.19e0.66 kg/m 3 /day). MAC MFCs achieved 80% of contaminant removal at the hydraulic retention time (HRT) of 20 h but the contaminant removal deceased to 66% at the HRT of 5 h. In addition, metal-doped manganese dioxide (MnO 2) cathodes were developed to replace the costly platinum cathodes, and exhibited high power density. CueMnO 2 cathodes produced 465 mW/m 2 and CoeMnO 2 cathodes produced 500 mW/m 2. Due to the cathode fouling of the precipitation of calcium and sodium, a decrease in the power density (from 400 to 150 mW/m 2) and an increase in internal resistance (R in) (from 175 to 225 U) were observed in MAC MFCs.
Journal of Applied Electrochemistry, 2016
A four-air cathode single-chamber microbial fuel cell (4ACMFC) with MnO 2 as cathode catalyst and a packed bed of graphite granules as anode was studied, aiming at continuous treatment of municipal wastewater in parallel to electric power production. When fed with synthetic wastewater, the system achieved a maximum power density of 13.6 W m-3 , a COD removal of 85 %, and a Coulombic efficiency (CE) of 21 %. When municipal wastewater was treated, the achieved COD removal was 45 %, and the CE 7.8 %. By increasing the municipal wastewater conductivity through salt addition, the CE increased to 22.3 %. During the long-term operation of the cell, non-exoelectrogenic bacteria and catalyst degradation were observed to be present. The 4ACMFC performance was assessed at different hydraulic retention times. The electrochemical impedance characterization of the 4ACMFC was also carried out.
Bioelectrochemistry, 2009
Single chambered mediatorless microbial fuel cell (MFC Nafion-117 membrane) fabricated with non-catalyzed electrodes was operated with open-air cathode to evaluate bioelectricity generation from domestic wastewater under acidogenic conditions (pH, 6) using anaerobic mixed consortia as anodic biocatalyst. Experimental data illustrated the feasibility of bioelectricity generation from domestic wastewater treatment. A steady increase in MFC performance was observed from the first cycle (0.248 V; 27.3 mW/m 2 ; 1.06 W/kg COD R ) during the startup phase prior to stabilization on fourth cycle (0.449 V; 144.6 mW/m 2 ; 4.64 W/kg COD R ). Sharp increase in power generation was observed after the fourth hour (125.4 mW/m 2 ; 289.61 mA/m 2 ) which continued up to the sixth hour (155.92 mW/m 2 ; 325.51 mA/m 2 ) and gradually decreased thereafter. Voltammogram evidenced clear redox peaks (E 0 ′, −0.334 V) related to redox mediator NAD + /NADH (E 0 ′, −0.32 V) suggesting a strong reducing phase. Higher energy (1.33 J) was observed at the fourth hour in concurrence with the effective electron discharge and higher substrate degradation.
International Journal of Hydrogen Energy, 2013
The potential of single chamber microbial fuel cells (SCMFC) to treat raw, fresh human urine was investigated. The power generation (55 mW) of the SCMFCs with platinum (Pt)based cathode was higher than those with Pt-free cathodes (23 mW) at the beginning of the tests, but this difference decreased over time. Up to 75% of the chemical oxygen demand (COD) in urine was reduced after a 4-day treatment. During this time, the ammonium concentration increased significantly to 5 gNH 4 þ-N/L in SCMFCs due to urea hydrolysis, while sulfate concentration decreased and transformed into H 2 S due to sulfate reduction reactions. Calcium and magnesium concentrations dropped due to precipitation at high pH, and phosphorous decreased 20e50% due to the formation of struvite that was found on the cathode surface and on the bottom of the anodic chamber. The advantages of power generation, COD removal, and nutrient recovery make SCMFCs treating human urine a cost-effective biotechnology.
Production of electricity during wastewater treatment using a single chamber microbial fuel cell
2004
Microbial fuel cells (MFCs) have been used to produce electricity from different compounds, including acetate, lactate, and glucose. We demonstrate here that it is also possible to produce electricity in a MFC from domestic wastewater, while at the same time accomplishing biological wastewater treatment (removal of chemical oxygen demand; COD). Tests were conducted using a single chamber microbial fuel cell (SCMFC) containing eight graphite electrodes (anodes) and a single air cathode. The system was operated under continuous flow conditions with primary clarifier effluent obtained from a local wastewater treatment plant. The prototype SCMFC reactor generated electrical power (maximum of 26 mW m -2 ) while removing up to 80% of the COD of the wastewater. Power output was proportional to the hydraulic retention time over a range of 3-33 h and to the influent wastewater strength over a range of 50-220 mg/L of COD. Current generation was controlled primarily by the efficiency of the cathode. Optimal cathode performance was obtained by allowing passive air flow rather than forced air flow (4.5-5.5 L/min). The Coulombic efficiency of the system, based on COD removal and current generation, was <12% indicating a substantial fraction of the organic matter was lost without current generation. Bioreactors based on power generation in MFCs may represent a completely new approach to wastewater treatment. If power generation in these systems can be increased, MFC technology may provide a new method to offset wastewater treatment plant operating costs, making advanced wastewater treatment more affordable for both developing and industrialized nations.
Water formation at the cathode and sodium recovery using Microbial Fuel Cells (MFCs)
Sustainable Energy Technologies and Assessments, 2014
Microbial Fuel Cells (MFCs) utilise biodegradable carbon compounds in organic waste to generate electric current. The aim of this work was to enhance MFC performance by using low cost and catalyst (platinum)-free cathode materials. The results showed that the range of Pt-free cathodes including activated carbon, plain carbon fibre veil with and without microporous layer (MPL) in two-chamber MFCs generated power with simultaneous catholyte generation in the cathode chamber. This is the first time to report a clear catholyte formation on the cathode half cell, which was directly related to MFC power performance. The importance of this phenomenon may be attributed to the oxygen reduction reaction, water diffusion and electroosmotic drag. The synthesised catholyte in situ on the open-to-air cathode appeared to be sodium salts (9% w/v concentration), which was recovered from the anolyte feedstock containing sludge and sodium acetate. An overlooked benefit of catholyte formation and accumulation contributes greatly to the overall wastewater treatment, water recovery, bioremediation of salts and carbon capture.
The objective of this study was to evaluate the performance of an upflow membrane-less microbial fuel cell (UFML MFC) with various types of carbon material as cathodes in power output and chemical oxygen demand (COD) reduction. The UFML MFC was designed with carbon felt as anode material, and the bioreactor was filled with 0.6-cm diameter of gravel at the anode region. Carbon flake, Pt-loaded carbon paper, and carbon felt were used as cathode electrodes. The voltage output (power density) for the carbon flake cathode and Pt-loaded carbon paper cathode was 384± 16 mV (44.4±2.5 mW/m 2 ) and 399±9 mV (44.1± 3 mW/m 2 ), respectively. The percentage of COD reduction at the anode region and effluent was above 75 and 85 %, respectively, for all cathode materials. The coulombic efficiency was 15.95, 6.09, and 15.32 % for Ptloaded carbon paper, carbon felt, and carbon flake, respectively. The result suggests that power generation and COD reduction were influenced by the cathode material. Carbon flake can be considered as a costeffective cathode material in UFML MFC for future application in real biological wastewater treatment process.
Brewery wastewater treatment using air-cathode microbial fuel cells
Applied Microbiology and Biotechnology, 2008
Effective wastewater treatment using microbial fuel cells (MFCs) will require a better understanding of how operational parameters and solution chemistry affect treatment efficiency, but few studies have examined power generation using actual wastewaters. The efficiency of wastewater treatment of a beer brewery wastewater was examined here in terms of maximum power densities, Coulombic efficiencies (CEs), and chemical oxygen demand (COD) removal as a function of temperature and wastewater strength. Decreasing the temperature from 30°C to 20°C reduced the maximum power density from 205 mW/m2 (5.1 W/m3, 0.76 A/m2; 30°C) to 170 mW/m2 (20°C). COD removals (R COD) and CEs decreased only slightly with temperature. The buffering capacity strongly affected reactor performance. The addition of a 50-mM phosphate buffer increased power output by 136% to 438 mW/m2, and 200 mM buffer increased power by 158% to 528 mW/m2. In the absence of salts (NaCl), maximum power output varied linearly with wastewater strength (84 to 2,240 mg COD/L) from 29 to 205 mW/m2. When NaCl was added to increase conductivity, power output followed a Monod-like relationship with wastewater strength. The maximum power (P max) increased in proportion to the solution conductivity, but the half-saturation constant was relatively unaffected and showed no correlation to solution conductivity. These results show that brewery wastewater can be effectively treated using MFCs, but that achievable power densities will depend on wastewater strength, solution conductivity, and buffering capacity.