Osmotic Microbial Fuel Cell Research Articles

Self-Aerated Osmotic Microbial Fuel Cell System Based on Siphon Principle: Performance Investigation and Application Significance

Self-Aerated Osmotic Microbial Fuel Cell System Based on Siphon Principle: Performance Investigation and Application Significance

Efficient sulfamethoxazole removal, water recovery and electricity generation were achieved simultaneously by osmotic microbial fuel cell in treating antibiotic wastewater

Microbial fuel cell (MFC) processes are associated with poor effluent quality when treating antibiotic wastewater. This study innovatively applied osmotic microbial fuel cell (OsMFC) technology to treat antibiotic wastewater while achieving the efficient removal of sulfamethoxazole (SMX), producing high-quality water, and generating electricity. During the stable operation of the OsMFC system, the chemical oxygen demand (COD) removal efficiency reached 80.1%, and the SMX removal efficiency reached 99.3% owing to forward osmotic membrane interception and biodegradation. The high-quality water production rate was 25% ± 5%. Interestingly, the addition of SMX improved the electrochemical performance of the system. The maximum power density was 4,642.4 mW/m3, and the internal resistance was only 230.7 Ω. During long-term operation of the system, membrane fouling was slight, and proteins were the main component of the fouling, followed by α-D glucopyranose polysaccharides and β-D glucopyranose polysaccharides. This study provides a new approach for the treatment of antibiotic wastewater and a novel method for the biodegradation of challenging emerging pollutants.

Enhancing proton conduction by regulating proton carrier position in polyamide layer of forward osmosis membrane in osmotic microbial fuel cell

Osmotic microbial fuel cell (OsMFC) encounters the problem of slow transport of proton, which results in a pH imbalance between the anode and cathode, and then a decreased cell performance. Forward osmosis (FO) membrane plays a critical role in proton transport in OsMFC, but the proton transmembrane migration is greatly hindered by the absence of particular proton transfer unit in FO membrane. In this study, high proton conductive carrier sulfo (−SO3H) was imported in the polyamide (PA) layer of FO membrane. The results demonstrated that the position of sulfo on benzene ring in PA polymer chain had a significant effect on proton migration and further the OsMFC property. As sulfo is in the ortho and para of the amino group on benzene ring, the optimal FO-1 membrane was acquired. It indicated that the OsMFC loaded with FO-1 membrane completed 88.31 % increase of water extraction, 50.72 % promotion of maximum power density and 6.02 % enhancement of chemical oxygen demand (COD) removal compared to those of the OsMFC with commercial FO membrane. The molecular dynamics simulation elucidated that the hydrogen bond and electrostatic interaction between atoms both played crucial roles in the proton-transfer process. This method of introducing proton carrier at molecular level aiming to alleviate the rising catholyte pH is economical and convenient for the potential scale-up applications of the OsMFC.

Simultaneous Wastewater Treatment and Resources Recovery by Forward Osmosis Coupled with Microbial Fuel Cell: A Review.

Osmotic microbial fuel cells (OsMFCs) with the abilities to simultaneously treat wastewater, produce clean water, and electricity provided a novel approach for the application of microbial fuel cell (MFC) and forward osmosis (FO). This synergistic merging of functions significantly improved the performances of OsMFCs. Nonetheless, despite their promising potential, OsMFCs currently receive inadequate attention in wastewater treatment, water reclamation, and energy recovery. In this review, we delved into the cooperation mechanisms between the MFC and the FO. MFC facilitates the FO process by promoting water flux, reducing reverse solute flux (RSF), and degrading contaminants in the feed solution (FS). Moreover, the water flux based on the FO principle contributed to MFC's electricity generation capability. Furthermore, we summarized the potential roles of OsMFCs in resource recovery, including nutrient, energy, and water recovery, and identified the key factors, such as configurations, FO membranes, and draw solutions (DS). We prospected the practical applications of OsMFCs in the future, including their capabilities to remove emerging pollutants. Finally, we also highlighted the existing challenges in membrane fouling, system expansion, and RSF. We hope this review serves as a useful guide for the practical implementation of OsMFCs.

Inhibition Strategies of Reverse Solute Flux in Osmotic Microbial Fuel Cells: Take Forward Osmosis as Reference

Inhibition Strategies of Reverse Solute Flux in Osmotic Microbial Fuel Cells: Take Forward Osmosis as Reference

Osmotic microbial fuel cell for sustainable wastewater treatment along with desalination, bio-energy and resource recovery: A critical review

Osmotic microbial fuel cell (OsMFC) devises the synergy between microbial fuel cell (MFC) and forward osmosis (FO) and exhibits the combined advantages of MFC and FO. Its suitability to attain desalination (salt removal, 28–35 %), resource recovery (water flux, 1–13 LMH), and power production (power density, 12–29 W/m3), along with wastewater treatment (COD removal, 63–95 %) render the technology promising. However, various phenomena namely concentration polarization, membrane fouling, reverse solute flux, etc., limit the performance and scaled-up applications of OsMFC. Extensive research on the selection of materials and optimum operating conditions for OsMFC are required. In this review, the working principle and components of OsMFC along with its applications are addressed in detail. The paper elucidates the critical challenges and potential solutions, and provides enthralling insights for its sustainable development.

Performance improvement of the osmotic microbial fuel cell by the pre-treatment of anaerobic sewage sludge using solenoid magnetic field

ABSTRACT This study explored the effect of a solenoid magnetic field (SOMF) as a pre-treatment on anaerobic sewage sludge (ASS) before using it in an osmotic microbial fuel cell (OMFC) as an inoculant. The ASS efficiency in terms of colony-forming unit (CFU) was improved ten times by applying SOMF compared to the control conditions. The obtained highest power density, current density, and water flux in the OMFC were 32.70 ± 5 mW·m−2, 135.13 ± 15 mA·m−2, and 4.24 ± 0.11 L·m−2h−1 respectively, for 72 h at 1 mT magnetic field. The coulombic efficiency (CE) and chemical oxygen demand (COD) removal efficiency were increased to 40–45% and 4–5% respectively, compared to un-treated ASS. Also, the start-up time of the ASS-OMFC system was almost reduced to 1–2 days based on open circuit voltage data. On the other hand, increasing the pre-treatment intensity of SOMF with time, it decreased the performance of OMFC. Also, the low intensity with increased pre-treatment time up to a specific limit enhanced the performance of OMFC.

Osmotic Microbial Fuel Cell for Groundwater Softening, Defluoridation, Salinity Reduction, and Energy Production

Despite being the major source of freshwater, groundwater is contaminated with hardness, fluorides, salinity, and so on, and hence, its application for domestic/industrial purposes is severely limited. Existing remediation technologies demand both chemical and energy inputs. Therefore, in this study, an osmotic microbial fuel cell (OsMFC) was developed as an energy-positive and chemical-free technology to achieve simultaneous groundwater softening, defluoridation, salinity reduction, and bioelectricity production. High-quality water was extracted from wastewater in the OsMFC and was applied to reduce groundwater contaminants by dilution. The effects of feed/draw solution (FS/DS) ratio, membrane area, reactor volume, and time on water flux, energy production, and reduction efficiencies of Na+, Cl−, total hardness (TH), and F− were studied. The increase in FS/DS ratio and membrane area resulted in considerable improvement in the water flux, energy production, and contaminant reduction. However, an increase in the reactor volume had little effect on the overall performance. A maximum water flux of 9.81 litres per square meter per hour [LMH (L/m2/h)] with reduction efficiencies of 75.81%, 76.27%, 72.22%, and 65.76% for Na+, Cl−, TH, and F−, respectively, were obtained with an extended operating time of 168 h. Maximum chemical oxygen demand (COD) removal of 86.6% and current density of 0.34 mA/m3 were achieved simultaneously. The study demonstrated a sustainable approach of extracting high-quality water from wastewater and its application in groundwater remediation along with energy production.

Study on the Changes in the Microcosmic Environment in Forward Osmosis Membranes to Reduce Membrane Resistance.

Osmotic microbial fuel cells (OsMFCs) are an emerging wastewater treatment technology in bioelectricity generation, organic substrate removal, and wastewater reclamation. To address this issue, proton-conductive sites were strengthened after using the forward osmosis (FO) membrane by reducing the membrane resistance. The mechanism of improving electricity generation was attributed mainly to the unique characteristics of the membrane material and the water flux characteristics of the FO membrane. In particular, only when the concentration of catholyte was greater than 0.3 M was the membrane resistance the main contributor to the overall internal resistance. Meanwhile, through the simulation of the concentration inside the membrane, the changes in the membrane thickness direction and the phase transition of the internal structure of the membrane from the dry state (0% water content) to the expansion state (>50%water content) were analyzed, which were influenced by the water flux, further explaining the important role of the membrane’s microenvironment in reducing the membrane impedance. This further opens a novel avenue for the use of OsMFCs in practical engineering applications.

Prediction and optimization of the performance in an osmotic microbial fuel cell for water purification and bioelectricity production using a developed process model

To better understand and mathematically express the process of osmotic microbial fuel cells (OsMFCs), a model describing the integration of electrogen growth kinetics and osmotic mass transfer was developed and validated in this study. Low root mean square error (RMSE) and mean relative error (MRE) were obtained for simulated water flux, voltage generation, and chemical oxygen demand (COD) removal, which revealed a reasonable accuracy of the developed model. The local sensitivity analysis indicated that operating parameters such as draw solution concentration, anode hydraulic retention time (HRT) and influent COD concentration played important roles in influencing the key performance of OsMFCs. At the benchmark settings of anode HRT (4 h), influent COD (880 mg L−1), and external resistance (3000 Ω), a voltage increment of approximately 9.4% was predicted with an increased draw solution concentration from ∼0 to 3.0 mol L−1 (sodium chloride, NaCl), revealing the merit brought by the combined effects of water flux-facilitated proton advection and the high conductivities of electrolytes in OsMFCs. Shortening the anode HRT from 14 to 0.5 h at a fixed draw solution concentration of 0.5 mol L−1 was able to achieve approximately 9.3% increment in voltage output, whereas, the COD removal compromised from 99.2% to less than 20%. High COD removal rate of over 95% was obtained when the examined influent COD was as low as approximately 300 mg L−1. The optimization of combined parameters indicated that the optimized operation was at a draw solution concentration of ∼1.0 mol L−1 (NaCl), anode HRT ranging between 4 and 8 h, and a low influent COD of ∼300 mg L−1 at the model settings.

Facilitating proton transport by endowing forward osmosis membrane with proton conductive sites in osmotic microbial fuel cell

A major challenge of the osmotic microbial fuel cell (OsMFC) application is the sluggish proton transport from anode to cathode. As a result, an extra overpotential is caused by the remarkable catholyte alkalinization and anolyte acidification. Thus, the efficiency of water extraction and biodegradation of organic pollutants are adversely affected simultaneously. To address this issue, proton conductive sites were introduced into the forward osmosis (FO) membrane by importing sulfonic acid radical groups. The results demonstrated that the proton transport flux improved after FO membrane modification. The OsMFC system with an optimal FO membrane achieved a 58.86 % reduction in artificial seawater salinity, enhanced the volume of water extraction by 61.90 %, increased the chemical oxygen demand removal efficiency by 6.39 %, and improved the current density by 16.56 %. In particular, the maximum power density of the optimized OsMFC (7.08 ± 0.42 W·m−3) was enhanced by 108.85 % and 60.18 % compared with those with Nafion and pristine FO membrane, respectively. Meanwhile, the mechanism of proton transport in the OsMFC system has been elucidated. The proton migration was reinforced under the synergistic effect of improved water flux and electromigration derived from internal electric field. This method to mitigate the catholyte pH through self-buffering in situ is green and economical. This will further open a novel avenue for OsMFC application in large-scale actual wastewater treatment.

Treatment of agro-food industrial waste streams using osmotic microbial fuel cells: Performance and potential improvement measures

Osmotic microbial fuel cell (OsMFC) is an emerging wastewater treatment technology which incorporates multiple functions such as bioelectricity generation, organic substrate removal, and wastewater reclamation. This study firstly reported the performance and potential improvement measures of OsMFCs in treating selected agro-food industrial waste streams, i.e., brewery wastewater (BW), sweetener process wastewater (ST), and swine wastewater (SW). BW and SW wastewaters with good biodegradability, showed high power density (11.1 and 9.3 W/m 3 ) and soluble chemical oxidation demand (sCOD) removal (89.2 ± 4.1 and 70.9 ± 3.8%) in OsMFCs. In contrast, OsMFC showed low performance with ST wastewater despite its high sCOD load. Possibilities in improving the treatment performance through modifying the operational and process settings were further explored. Shortening anode hydraulic retention time (HRT) was able to improve the bioelectricity generation and water production, whereas slightly compensated the sCOD and nutrient removal efficiencies. However, this approach showed limited effect in enhancing the ST-OsMFC. A pre-fermentation process with a minimum HRT of approximately 20 h was recommended to enhance the treatability of ST wastewater by previously converting the complex organic substrates in the raw water into volatile fatty acid (VFA). • First report in OsMFC treating industrial wastewater. • Treatment of different agro-food industrial waste streams by OsMFC was demonstrated. • An anode HRT of 9 h is recommended for OsMFC treating selected agro-food waste streams. • Pre-fermentation is an option to improve the treatability of sweetener wastewater in OsMFC.

Study on the Effect of Water Flux in Osmotic Microbial Fuel Cells on Membrane Water Content and Resistance

Osmotic microbial fuel cells (OsMFCs) can integrate forward osmosis into microbial fuel cells (MFCs), which are able to perform organic elimination, bioenergy production, and high-class water abstraction from wastewater. However, it is not well understood how the unique feature of OsMFCs, i.e., water flux, helps improve current generation. Based on experimental studies and the Springer model theory, a new method for representing water transmission in OsMFC membranes is put forward that considers water transmission by electro-osmosis resulting from proton flux through the membrane and by osmosis resulting from osmotic pressure grades of water. In this research, osmotic water transmission is associated with the permeable differential pressure resulting from the ionic differential concentration in the membrane, and electro-osmotic water transmission is found to be proportional to the current density employed but irrelevant to the composition gradients. The net water transmission in OsMFC depends on the operation time and increases accordingly with higher current density and composition gradients. Furthermore, the membrane’s proton conductibility and water-transmission capabilities are significantly affected by the moisture content, which decreases from the negative electrode to the positive electrode in the OsMFC system. Increasing water flux with higher osmotic pressure and current density is therefore able to diminish the resistance of the membrane.

Facilitating Proton Transport by Endowing Forward Osmosis Membrane with Proton Conductive S Ites in Osmotic Microbial Fuel Cell

Facilitating Proton Transport by Endowing Forward Osmosis Membrane with Proton Conductive S Ites in Osmotic Microbial Fuel Cell

Performance of photopolymerized active layer forward osmosis membrane in the osmotic microbial fuel cell

Osmotic microbial fuel cell (OMFC) is evolved by substituting the proton exchange membrane (PEM) by forward osmosis (FO) membrane in a microbial fuel cell (MFC). This study tried to mitigate the dependency on commercial FO membranes to enhance the mutual benefits between MFC and FO. We investigated the performance of photo-polymerized active layer FO membranes in OMFC with feed as a synthetic wastewater and draw solution as 35 g/L NaCl solution and compared by commercial HTI cellulose triacetate (CTA) membrane. Poly (ethylene glycol) phenyl ether acrylate (PPEA) monomer and methacrylic acid (MAA) monomer was used in different ratio i.e., 100/0, 75/25, 50/50, 25/75 and 0/100 for preparation of active layer on our earlier work’s optimized substrate. Effect of the concentration of MAA had a significant effect on ion exchange capacity, water uptake, and oxygen and proton mass transfer. Among all prepared membranes, the 75/25 FO membrane showed the highest power density of 237.23 ± 0.90 mW/m 2 and average water flux 0.95 ± 0.71 LMH. • Photo-polymerized active layer FO membranes were investigated in OMFC. • PPEA and MAA were used as monomers to prepared FO membranes. • The concentration of MAA was found a significant parameter. • 75/25 FO membrane showed highest performance than CTA FO membrane.

Concentrating nutrients and recovering water and energy from source separated urine using osmotic microbial fuel cell

This work presents the use of osmotic microbial fuel cell (OsMFC), for the first time, to concentrate nutrients and recover water and energy from source separated urine. Four sets of concentration of fresh urine as feed and NaCl as draw were examined: 10% fresh urine vs 0.25 M NaCl; 10% fresh urine vs 2 M NaCl; fresh urine vs 0.25 M NaCl; and fresh urine vs 2 M NaCl. A maximum water flux of 14.27 LMH was attained when 10% of fresh urine and 2 M of NaCl were used as feed and draw solutions, respectively. Additionally, OsMFC concentrates ~99% of TOC, TN, NH4+, and 100% of PO43− and NO3− from urine at the feed side. Polarization studies indicate that the power generation in OsMFC is related to the rate of change of conductivity and the initial conductivity of the anolyte. The maximum (0.12187 W m−3) and minimum power densities (5.3372 × 10−4 W m−3) were obtained for the conditions of fresh urine vs 0.25 M NaCl and 10% fresh urine vs 0.25 M NaCl, respectively. The study shows that OsMFC is an effective pretreatment process to concentrate nutrients from urine by recovering water and energy, simultaneously.

Membrane cleaning and performance insight of osmotic microbial fuel cell

Osmotic microbial fuel cell (OsMFC) integrating forward osmosis into microbial fuel cell (MFC) favors the merits of organic removal, bioenergy generation, and high-quality water extraction from wastewater. This study demonstrated an 18.7% power density enhancement over a conventional MFC due to the water-flux-facilitated proton advection and net positive charge (NPC)-flux-promoted countercurrent proton exchange. Among the three examined membrane cleaning methods, chemical cleaning using 0.2% NaClO was found to be especially effective in removing organic foulants composed of proteins and polysaccharides, resulting in a water flux recovery of up to 91.6% with minimal impact on average maximum power density and internal resistance. The effects of operating parameters including anode HRT and draw solution concentration were studied. Shortening HRT from 6.0 to 3.0 h increased power density by 78.0% due to a high organic loading rate and a slightly reduced polarization concentration. Increasing draw solution concentration from 0.2 to 1.0 M NaCl enhanced power density by approximately 2.7-fold due to enhanced proton advection. Water-flux-facilitated proton advection played a more important role in determining the electricity generation performance of OsMFC than the NPC-flux-promoted countercurrent proton exchange under varied operating conditions.

Electricity generation and pollutants removal of landfill leachate by osmotic microbial fuel cells with different forward osmosis membranes

In this study, thin-film composite with embedded polyester screen, cellulose triacetate with a cast nonwoven and cellulose triacetate with embedded polyester screen (CTA-ES) was examined as the intermediate membranes in osmotic microbial fuel cells (OsMFCs). The reactors were fed with actual landfill leachate and the performance was studied in two operation modes: active layer facing draw solution and active layer facing feed solution (AL-FS). The OsMFC with CTA-ES exhibited the best energy generation (maximum power density: 0.44 W m− 2) and pollutant removal efficiency (ammonia nitrogen: 70%, total nitrogen: 74%) in the AL-FS mode, which could be ascribed to the lowest internal resistance (237 Ω) and highest microbial richness. Pseudomonas was the highest proportion of microbial in OsMFCs. The result of this study has demonstrated the potential of OsMFCs for landfill leachate treatment.

Effect of sound waves and inclination of membrane on the performance of the osmotic microbial fuel cell

This study aimed to explore the effect of the sound wave and membrane inclination i.e., 45° and 90° (MI45 and MI90) on the performance of osmotic microbial fuel cell (OMFC). The vibrations were given by a sound intensity of 60–80 dB and 20–1000 Hz in an anode compartment for a period of 5–6 h per day. Membrane inclination was given to maximizing the effective surface area under a fixed plane without changing its volumetric capacity to enhance water flux. Membrane inclination increased the effective surface area up to 33.33%, therefore, water flux was increased by 10% by using 45° inclination. The OMFC produced maximum water flux, reverse salt flux and power density of 0.750 ± 0.02 and 0.666 ± 0.02 Lm-2h−1, 3.18 ± 0.02 and 3.10 ± 0.02 gm-2h−1, 35.22 ± 12 and 24.22 ± 08 mW.m−2 for MI45 and MI90 respectively with the effect of sound. The chemical oxygen demand (COD) removal was found 66.85 ± 1% and 59.51 ± 1% with and without the effect of sound. Therefore, sound reduced the OMFC start-up time by 2–3 days based on open-circuit voltage data and also increased the anaerobic degradation by 6–9%. Overall, sound stimulates bacterial growth for the degradation of organic matter, and membrane inclination gives a more effective surface area for water flux.

Simultaneous hexavalent chromium removal, water reclamation and electricity generation in osmotic bio-electrochemical system

For the first time, an osmotic microbial fuel cell (OsMFC) was employed for simultaneous hexavalent chromium [Cr(VI)] removal, organic contaminant removal, energy production, and water reclamation. In this system, draw solutions were prepared from 0 to 1 M NaCl mixed with 12 mg/L Cr(VI). Cr(VI) reduction and power generation at different pH were studied. In terms of power generation, the results revealed that the highest power density of 6.6 mW/m2 (170 mW/m3) was obtained using the 1 M NaCl catholyte at pH 7. However, the greater Cr(VI) reduction of 44.5% and 97.6% was achieved using the 0.2 M NaCl/Cr(VI) based catholyte at pH 7 and 2, respectively. This can be attributed to the competition between Cr(VI) and oxygen reduction due to the high rate of dilution at higher concentrations of NaCl. Additionally, the highest open-circuit voltage of 0.752–0.845 V was recorded at 0.2 M NaCl/Cr(VI) as a proof to support that 0.2 M NaCl was a favorite condition for reducing Cr(VI). Moreover, through cyclic voltammetry, the signals of oxidation-reduction peaks were observed in the case of 0.2 M NaCl/Cr(VI), while, reduction peaks mostly disappeared in other cases. Additionally, more precipitate [Cr(OH)3(s)] was observed to be deposited on the surface of the cathode electrode when 0.2 M NaCl was used as the draw solution. Hence, 0.2 M NaCl was the optimal catholyte concentration for Cr(VI) reduction. The Cr(VI) removal efficiency was 97.6% for an initial pH of 2 with the 0.2 M NaCl catholyte because low pH is thermodynamically favored for Cr(VI) reduction.