Performance Of Microbial Desalination Cell Research Articles

Development of microbial desalination cells for the treatment of reverse osmosis reject water: A new benchtop approach

To address the growing global demand for usable water, there is an immediate necessity to enhance wastewater treatment systems. A continuous mode adaption of the conventional three-chamber microbial desalination cell (MDC) configuration was used, with gravity facilitating the flow of residential reject water for desalination. Initially, operating in batch mode with a 100 mL treatment volume, the single microbial desalination machine was expanded to 300 mL in continuous mode, capable of treating 5 L of home refuse water over 36 days. The batch mode MDC had a maximum current and power density of 3.81 µA/cm2 and 0.337 µW/cm2, resulting in 76 % desalination and 83.9 % COD eradication rates. Scaling up increased the MDC's performance, reaching a maximum of 0.45 µW/cm2 and 5.31 µA/cm2, which was 1.3 times greater than batch mode operation. The current work demonstrates the feasibility of microbial desalination cells and their novel approach for treating much higher quantities of reverse osmosis (R.O.) saline water in a comparable period of roughly 36 days. It emphasizes the actual limits when dealing with real-world wastewater samples, presenting a unique path for biotechnology by simultaneously generating bio-electricity and tackling future contaminants. Furthermore, incorporating desalination chambers with microbial fuel cells increases efficiency and opens up new options for enhanced wastewater treatment, resource recovery, and bioenergy generation. This pioneering strategy uses innovative membrane technologies and microbial optimization approaches to push the limits of desalination.

Exploring the role of domesticated resistors in batch-mode microbial desalination cell

Microbial Desalination Cells (MDCs) are an electrochemical process that harnesses microbial reactions to simultaneously treat wastewater, generate power, and desalinate water. By utilizing microbial decomposition of organic pollutants in wastewater, MDCs offer a sustainable and energy-efficient alternative to conventional desalination technologies. The technical framework of MDCs emphasizes the integration of water-electricity principles, making them promising for future applications in seawater desalination, wastewater treatment, resource recovery, and water softening. This study investigates the impact of acclimation resistance, represented by four different domesticated resistors values of 1 kΩ, 100Ω, 51Ω, and 10Ω, on the performance of MDCs. Larger acclimation resistors exhibit higher power performance, with the case of 100Ω achieving a power density of 0.33 mA/m2 and the case of 1 kΩ achieving the highest current density of 1.90 mA/m2. Furthermore, the case with an acclimation resistance of 1 kΩ exhibits superior performance in terms of chemical oxygen demand (COD) removal, achieving a removal rate of 76.3% on day 1. Conversely, the case with an acclimation resistance of 10Ω demonstrates the best desalination performance, achieving a desalination rate of 9.0%. It should be noted that the optimal performance in terms of COD removal and desalination capacity varies due to the various operational mechanisms involved. . The findings of this study provide valuable insights for enhancing the performance of MDCs in future applications, enabling further improvements in their efficiency and effectiveness.

Utilizing a Fe3O4 Magnetite Nanoparticle for Anode Modification in a Microbial Desalination Cell to Treat Saltwater.

The microbial desalination cell (MDC) is a bio-electrochemical system that exhibits the ability to oxidize organic compounds, produce energy, and decrease the saline concentrations within the desalination chamber. The selective removal of ions from the desalination chamber is significantly influenced by the anion and cation exchange membranes. In this study, a three-chamber microbial desalination cell was developed to treat seawater using a synthesize Fe3O4 magnetite nanoparticle (MNP)-modified anode. The impact of different performance parameters, such as temperature, pH, and concentrations of NPs, has been investigated in order to assess the performance of three-chamber MDCs in terms of energy recovery and salt removal. The evaluation criteria of the system included multiple factors such as chemical oxygen demand (COD), Coulombic efficiency (CE), desalination efficiency, as well as system aspects including voltage generation and power density. The highest COD% removal efficiency was 74% at 37°C, pH = 7, and 30g/L salt concentration with an optimized NPs concentration of 2.0mg/cm2 impregnated on anode. The maximum Coulombic efficiency was 10.3% with the maximum power density of 4.3W/m3. The effect of the nanoparticle concentration impregnated on the anode was clarified by the primary factor of analysis. This research has revealed consistent patterns in the enhancement of voltage generation, COD, and Coulombic efficiencies when incorporating higher concentrations of nanoparticles on the anode at a certain point.

Impact of different electrodes, mediators, and microbial cultures on wastewater treatment and power generation in the microbial desalination cell (MDC).

Microbial desalination cell (MDC) can treat wastewater and saline water simultaneously and generate power. The aim of the present research work was to identify the critical factors influencing COD reduction and power generation from the MDC reactor and to optimize the control parameters. The experimental study was conducted by using medium to high-strength wastewater from distillery and brewery industry in batch-wise operation. The maximum voltage of 702 mV and current of 2.16 mA were observed for the carbon brush electrode. The mediated aeration process with the presence of potassium ferricyanide was reported in 87% COD reduction and 992 mV voltage generation. The presence of the microbial culture provided 82% COD reduction and 51% TDS reduction. The maximum current density (CD) of 0.04 mA/cm2 was observed for carbon brush, and a maximum power density (PD) of 15.56 mW/cm2 was found with aeration and potassium ferricyanide mediator. This study provided insight towards the impact of the electrode materials and the effects of mediator, aeration, and microbial culture on MDC performance.

Exploring the potential of metal-doped perovskite-oxides as oxygen reduction catalyst for enhancing the performance of microbial desalination cells

Microbial desalination cells (MDCs) have been employed for dissolved salts and contaminant removal along with electricity production. Although oxygen depletion is a momentous reaction in the electrochemical energy transformation, its sluggish kinetics prevent it from being accustomed to fuel cells. Oxygen reduction reactions (ORR) in alkaline environments and perovskite oxide catalysts for converting energy electrochemically have emerged as excellent and promising alternatives. Various concentration of Sn-doped oxygen-deficient BaTiO3 was incorporated to study ORR behavior and effect on MDC performance. This perovskite catalyst contains a considerable percentage of cubic BaTiO3 (with 100 nm size) confirmed by material characterization studies. Power density obtained in the absence of the catalyst was 4.7 W/m3 which increased to 6.7 W/m3 upon utilization of BaTiO3 with salt removal of 76.7%. Catalyst loading of 1 mg/cm2 and initial total dissolved solid (TDS) concentration of 20 g/L was found to be effective for improving the desalination rate in MDC. Electrochemical analyses also revealed enhancement in electrocatalytic behavior of cathodic kinetics under such operating conditions. Thus, Sn-doped BaTiO3 catalyst can be a suitable candidate for upscaling of MDC to meet the sustainable development goals.

Improved defluoridation and energy production using dimethyl sulfoxide modified carbon cloth as bioanode in microbial desalination cell

In the present study, carbon cloth (CC) was functionalized using dimethyl sulfoxide (DMSO) and employed as an excellent bioanode for improving defluoridation efficiency, wastewater treatment, and power output from a microbial desalination cell (MDC). The Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis of DMSO modified carbon cloth (CCDMSO) confirmed the functionalization of CCDMSO, and the water drop contact angle of 0° ensured its superior hydrophilicity. The presence of –COOH (carboxyl), SO (sulfoxide) and O–CO (carbonyl) functional groups on CCDMSO aids in enhancing the performance of the MDC. Besides, cyclic voltametric and electrochemical impedance analysis revealed that CCDMSO had an excellent electrochemical performance with low charge transfer resistance. Replacing CC with CCDMSO as anode in MDC, the time required for 3,10 and 20 mg/L of initial fluoride (F−) concentrations in the middle chamber was reduced from 24 ± 0.75 to 17 ± 0.37, 72 ± 1 to 48 ± 0.70, and 120 ± 0.5 to 96 ± 0.53 h, respectively to meet the prescribed standards (1.5 mg/L). Furthermore, using CCDMSO, the anode chamber of MDC exhibited a maximum of 83% substrate degradation, and simultaneously, the power output is increased by 2–2.8 times. CCDMSO improved the power production from 0.009 ± 0.003, 1.394 ± 0.06 and 1.423 ± 0.15 mW/m2 to 0.020 ± 0.07, 2.748 ± 0.22 and 3.245 ± 0.16 mW/m2, respectively, for initial F− concentrations of 3,10, and 20 mg/L. Modifying CC with DMSO thus proved to be an efficient and simple methodology for enhancing the overall performance of MDC.

Combination of H2O2-producing microbial desalination cells and UV/H2O2 advanced oxidation process: Water salinity reduction and microbial inactivation

Microbial desalination cells (MDCs) are bioelectrochemical devices that can recover usable energy and chemicals from organic wastes and concurrently desalinate saltwater. MDCs can also produce the green oxidant, H2O2, through a two-electron oxygen reduction reaction occurring on the cathode electrode. If MDCs producing H2O2 are used in the pretreatment of brackish water or seawater for reverse osmosis (RO) processes, the salinity of feed water can be reduced in MDCs and the MDC-produced H2O2 can be utilized onsite to oxidize organic contaminants or disinfect microorganisms in the feed water. This strategy of using MDC pretreatment may substantially alleviate the energy requirements and biofouling tendency of downstream RO units. Herein, we assessed the applicability of a combination of H2O2-producing MDCs and ultraviolet (UV) or UV254nn -based advanced oxidation process (AOP) (i.e., UV/H2O2) as pretreatment for RO processes. We first examined the effect of catholyte conditions, which is one of the most crucial factors directly affecting the H2O2 composition and decomposition, on the performance of MDCs. Then, we evaluated the microorganism disinfection efficiencies of advanced photo-oxidation processes using H2O2 obtained from MDCs. The MDC investigated herein achieved 93.1% desalination efficiency and > 5.0 mM H2O2 concentration. In addition, UV-based AOP with the produced H2O2 demonstrated up to 15-fold higher inactivation kinetics than that by UV254 nm disinfection alone.

Photosynthetic microbial desalination cell (PhMDC) using Chlamydomonas sp. (UKM6) and Scenedesmus sp. (UKM9) as biocatalysts for electricity production and water treatment

A current Microbial Desalination Cell (MDC) system often uses chemicals or air cathodes that are toxic and impractical for scalable applications. This work presents the MDC performance that utilized microalgae species Chlamydomonas sp. (UKM6) and Scenedesmus sp. (UKM9). These species supported the role of the terminal electron acceptor in the cathode chamber of photosynthetic MDCs (PhMDC). The results showed that PhMDC-UKM9 and UKM6 produced 1942 mW/m3 and 1714 mW/m3 power densities with 44% and 32% desalination rates, respectively. The desalination of salt concentration (35 g/L) was approaching the practical application of seawater. Both UKM6 and UKM9 achieved chemical oxygen demand (COD) removal in the anode chamber by 49% and 53%, respectively. 16S microbial community analysis in anolyte revealed phylum Firmicutes as the dominion community. This study demonstrated that the local microalgae species integrate power production, wastewater treatment, and water purification through PhMDC operation, comparable with other studies using commercial microalgae.

A Comprehensive Study on Air-Cathode Limitations and Its Mitigation Strategies in Microbial Desalination Cell—A Review

Microbial desalination cells (MDCs) are promising bioelectrochemical systems for desalination using the bacteria-generated electricity from the biodegradation of organic wastes contained in the wastewater. Instead of being a sustainable and eco-friendly desalination technology, the large-scale application of MDC was limited due to the high installation cost of the metal-catalyst-coated cathode electrode and the poor performance of the cathode in long-term operation due to catalyst fouling. Such cathodic limitations have hindered its large-scale application. The cathodic limitation has arisen mainly because of three losses, such as (1) Ohmic loss, (2) mass transfer loss, and (3) activation loss. The catalyst-assisted cathodic reduction reaction is an electrochemical surface phenomenon; thereby, the cathode’s surface charge transfer and thermodynamic efficiency are crucial for reaction kinetics. This review article aims to provide an overview of the MDC process, performance indicators, and summarizes the limiting factors that could hinder the process performance. Then, the article represented a comprehensive summary of the air-cathodic limitations and the mechanisms applied to improve the air-cathodic limitations in MDC to enhance the cathodic reaction kinetics through cathode surface modification through catalysts. The study is significantly different from other review studies by the precise identification and illustration of the cathodic losses and their mitigation strategies through surface modification. The details about the role of photocatalysts in the minimization of the cathode losses and improvement of the performance of MDC were well presented.

Effect of External load and Salt Concentration on the Performance of Microbial Desalination Cell

Microbial desalination cell (MDC) is one of the cost and energy effective methods that can help people in countries with low income and people in rural areas without energy infrastructure, get access to desalinated water while treating their wastewater. Despite the advantages of the technology, less is known about the behavior of the internal resistance in MDCs. Therefore, this study mainly focused on the behavior of the MDC from internal and external resistance point of view. The desalination rate of saltwater at different applied external resistance (995 , 464 , 220 , and 74 ) was studied. Moreover, the polarization capacity of the established MDC was investigated. The internal resistance of MDC at different salt concentrations of the desalination chamber (35-1 g/l) was also analyzed and discussed. The findings of the study showed that decreasing the external resistance could increase the current generation of the MDC as the main driving force of the desalination. Furthermore, it was found that salt concentration in the middle chamber plays a significant role on the internal resistance of MDC and hence on the desalination rate. Lower desalination rate at the lower salt concentration of the desalination chamber could be explained by the high internal resistance of the system. Therefore, integrating MDC with other suitable techniques, e.g., reverse osmosis (RO), for desalination of lower salt concentrations could overcome this challenge. MDC as a standalone desalination system at the current stage of technology might not be practical due to the low current performance of the system. However, it is worth considering it as green and low-cost technology for the pretreatment stage of the other conventional desalination systems, like RO with energy and cost savings while treating the wastewater.

3D electrode use in MDC for enhanced removal of boron from geothermal water

Microbial desalination cell (MDC) is a significantly promising technology due to its simultaneous features of electricity production, wastewater treatment and desalination. In this paper, the three-dimensional (3D) sponge with activated carbon-chitosan (AC-CS) was synthesized to enhance the efficiency of the MDC system. Effects of operating parameters (boron concentration, electrode surface area, catholyte solution, and activated sludge volume) on MDC performance were also investigated. The MDC with 3D AC-CS anode provided a higher power density of 970 mW/m2, boron removal efficiency of 75.9%, and COD removal efficiency of >90% under optimized conditions. The maximum boron and COD removal efficiencies were 65.6 and 81.4% with the power density of 866.9 mW/m2 for geothermal brine. Moreover, BET analysis showed that the 3D AC-CS anode presented high surface area (230 m2/g) and pore volume (0.202 cm3/g). As an overall result, not only the production of 3D sponge anode electrodes with AC-CS composite was achieved but also desalination and power generation results that were comparable with the literature were presented.

A state-of-the-art review on microbial desalination cells

The rapid growth in population has increased the demand for potable water. Available technologies for its generation are the desalination of sea water through reverse osmosis, electrodialysis etc., which are energy and cost intensive. In this context, microbial desalination cell (MDC) presents a low-cost and sustainable option which can simultaneously treat wastewater, desalinate saline water, produce electrical energy and recover nutrients from wastewater. This review paper is focussed on presenting a detailed analysis of MDCs starting from the principle of operation, microbial community analysis, basic architecture, evolution in design, operational challenges, effect of process parameters, scale-up studies, application in multiple arenas and future prospects. After thorough review, it can be inferred that MDCs can be used as a stand-alone option or pre-treatment step for conventional desalination techniques without the application of external energy. MDCs have been used in multiple applications ranging from desalination, remediation of contaminated water, recovery of energy and nutrients from wastewater, softening of hardwater, biohydrogen production to degradation of waste engine oil. Although, MDCs have been used for multiple applications, still a number of operational challenges have been reported viz., interference of co-existing ions during desalination, membrane fouling, pH imbalance and limited potential of exoelectrogens. However, the re-circulation of anolytes with electrodialysis chamber has led to the maintenance of optimal pH for favourable microbial growth leading to improvement in the overall performance of MDCs. In future, genetic engineering may be used for improving the electrogenic activity of microbial community, next generation materials may be used as anode and cathode, varied sources of wastewater may be explored as anolytes, life cycle analysis and exergy analysis may be carried out to study the impact on environment and detailed pilot scale studies have to be carried out for assessing the feasibility of operation at large scale.

Simultaneous energy production, boron and COD removal using a novel microbial desalination cell

This paper investigates simultaneous boron removal from aqueous solutions, organic matter removal from industrial wastewater and energy production using a Microbial Desalination Cell (MDC). Anode chamber of the conventional MDC cell was modified to include 3D cubic electrodes as a novel design. Effects of operating parameters, including electrode type (3D-electrode and 2D-electrode), anolyte solution temperature (20 °C, 40 °C, and 60 °C), and activated sludge:wastewater volumetric ratio (S:WW = 1:1, 1:2, and 1:5), on MDC performance were studied. Furthermore, real geothermal water treatment was investigated under optimum operating conditions. Boron and organic matter removal efficiencies and the produced power density results were promising for 3D-electrodes under optimum operating conditions. The maximum boron removal efficiency, COD removal efficiency, and power density were 55.5%, 91.5%, and 9.04 mW/m3 treating real geothermal water at optimum operating conditions. The analyses of Scanning Electron Microscope with Energy Dispersive X-ray spectrometer (SEM-EDX) demonstrated biofilm formation and salt deposition on membrane surfaces, which most probably reduced the performance of MDC. Consequently, our results showed that use of 3D-electrodes was a promising improvement to the conventional configurations with 2-D electrodes since removal efficiencies and energy production were comparable for a more compact electrode structure.

Nanomaterials-based air-cathodes use in microbial desalination cells for drinking water production: Synthesis, performance and release assessment

Global water desalination capacity is around 95 million m3 day−1, accounting for an enormous energy demand, thus low energy desalination technologies are needed. Microbial desalination cells (MDC), a bioelectrochemical reactor that allows water desalination while treating wastewater with low energy requirement represents a potential low energy solution. Air-cathode based MDC is a promising environmentally friendly reactor configuration as it reduces operational costs but has limited performance due to low cathode oxygen reduction reaction (ORR) kinetics. Air-cathodes with high ORR performance must be developed considering cost, performance and toxicologic characteristics. In the present work we developed two different carbon-based platinum free air-cathodes: iron doped carbon nanofibers (CNF-Fe) and gas diffusion electrodes based on MnO2 (MnO2-GDE). The air-cathodes demonstrated dissimilar ORR performances; CNF-Fe performed better at low overpotential while MnO2-GDE did better at high overpotentials. MDC reactors were tested employing both air-cathodes, achieving average output electrical current densities of 4.1 mA cm−2 and 1.3 mA cm−2 for MnO2-GDE and CNF-Fe, respectively. Also, the desalination performance of MDC employing MnO2-GDE was higher than CNF-Fe based MDC, reaching a salt removal rate of 4.8 g m−2 h−1 and 3.6 g m−2 h−1, respectively. Finally, the release of nanomaterials during both air-cathodes use in MDC operation was assessed, which represents the first study of this type to author’s knowledge. The results demonstrated some cathode catalyst release, but at a concentration below the threshold to represent a threat for the environment and humans.

Effect of internal and external resistances on desalination in microbial desalination cell

The green and cost-effective nature of the microbial desalination cell (MDC) make it a promising alternative for future sustainable desalination. However, MDC suffers from a low desalination rate that inhibits it being commercialized. External resistance (Rext) is one of the factors that significantly affect the desalination rate in MDCs, which is still under debate. This research, for the first time, investigated the impact of Rext on MDCs with different internal resistance (Rint) of the system to discover the optimal range of Rext for efficient MDC performance. The results showed that the effect of Rext on desalination rate (2.52 mg/h) was quite low when the Rint of MDC was high (200 Ω). However, operating the MDC with a low Rint (67 Ω) significantly improved the desalination rate (9.85 mg/h) and current generation. When MDC was operated with a low Rint the effect of variable Rext on desalination and current generation was noticeable. Therefore, low Rint (67 Ω) MDC was used to select the optimum Rext when the optimal range was found to be Rext ≪ Rint, Rext < Rint, Rext ≈ Rint (ranging from 1-69 Ω) to achieve the highest desalination rates (10.41-8.59 mg/h). The results showed the superior effect of Rint on desalination rate before selecting the optimal range of Rext in the outer circuit.

Modeling and simulation of the processes in desalination fuel cell fed with actual wetland brackish water

Microbial desalination cell (MDC) is a new sustainable technique for simultaneous desalination, bioelectrochemical treatment, and power generation. In this study, three mathematical models were adopted to describe the performance of two different configurations of MDC system; a conventional three-chambered MDC with single desalination chamber, and a stacked microbial desalination cell (SMDC) with three desalination chambers. Both systems were fueled with real sewage and fed actual wetland saline water. The performance of MDC and SMDC systems were evaluated based on organic content removal from real sewage, desalination of brackish water, and power generation. The mathematical models were; (1) electrochemical model based on electrochemical reactions and the diffusion of ions across membranes, (2) Monod model based on Monod kinetic equation, and (3) salt concentration balance model to reflect salinity removal in the desalination chambers. The predicted results demonstrated acceptable agreement with experimental results with determination coefficients R2 > 90%.

A New Method of Bio-Catalytic Surface Modification For Microbial Desalination Cell

Microbial desalination cell (MDC) built on surface modification has been studied for seawater desalination. Herein, the bio-catalytic surface modification for maintenance the long-term MDC performance during desalination process has been developed. The goal of this study is to provide and develop a seawater desalination system without requiring energy support by applying a modification of anode as an electron acceptor, and the different potential charges that occur between anode and cathode can play as driving force for electrodialysis of seawater desalination. Yeast has been applied as biocatalyst, meanwhile neutral red has been chosen as redox mediator to facilitate the electron transport from bioactivity of cells. Several types of surface modification have been conducted, i.e. biocatalyst-mediator immobilization and electropolymerization of NR at the surface of the anode. The optimization of each device has been characterized by cyclic voltammetry, chronoamperometry, and observed in Microbial fuel cell (MFC) prior functioned in MDC. The concentrations of salt ion migration have been determined by Ion Exchange Chromatography. MFC results reported that the best configuration of surface modification was obtained from CF/PNR then applied in MDC. CF/PNR delivered the highly significant performance by having the maximum value of all tested parameters, i.e 42.2% of current efficiency; 27.11% of bio-devices efficiency; 92.5 mA m-2 of current density and also 61% of NaCl transport. The profiles of surface devices have been detected by Scanning electron microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX). A several spherical shapes around 4 nm within alginate layer have been detected from SEM images and it was confirmed as yeast, meanwhile 5.04% of N has been found from EDX spectrum and was indicated from PNR. The results show that surface modification could be a promising method for bioelectricity generation which simultaneously produces electricity and seawater desalination and provides a green chemistry technology.

Simultaneous bioelectricity generation and water desalination using Oscillatoria sp. as biocatalyst in photosynthetic microbial desalination cell

Globally, the scarcity of drinking water has triggered the researchers towards the development of desalination techniques to turn up saline water into potable. Microbial Desalination Cell (MDC) is a novel green technology that shows potential approach for desalination along with electricity generation and wastewater treatment. However, the expensive catholyte/catalyst in the cathode side has limited the MDC for real time application. Hence, the main objective of this work was to investigate the electricity generation during dairy wastewater treatment and desalination efficiency using biocathode (Oscillatoria sp.) in the MDC. The results showed that the maximum open circuit voltage of 652 ± 10 mV, COD removal efficiency of 80.2 ± 0.5% and desalination efficiency of 65.8 ± 0.5%, were achieved respectively. The effect of saline water concentration was investigated and the performance of MDC was compared with real (sea) water. This study demonstrated that Oscillatoria sp. could be used as a potential biocatalyst in the cathode chamber for enhancing salinity removal along with electricity generation and wastewater treatment in the MDC.

Enhancing the performance of microbial desalination cells using δMnO2/graphene nanocomposite as a cathode catalyst

Abstract In this work, δMnO2 was anchored into graphene nanosheets via a mediated simple and eco-friendly approach to be used as a potential low-cost cathodic catalyst in microbial desalination cells (MDC). MnO2/G based MDC revealed a faster start-up and stable performance during the operation compared with the catalyst-free control MDC. The average chemical oxygen demand (COD) removal efficiencies were 85.11 ± 5.13 and 86.20 ± 4.85% and average columbic efficiencies throughout the operation cycles were 1.52 ± 0.32% and 0.70 ± 0.35% for MnO2/G based reactor and control reactor, respectively. The average desalination efficiencies were 15.67 ± 3.32 and 13.21 ± 2.61% for MnO2/G based reactor and control reactor, respectively. The superior catalytic performance of MnO2/G based cathode improved current generation which is the key desalination stimulus. MnO2/G based reactor revealed a lower internal resistance of 430 Ω compared with 485 Ω for the catalyst-free control reactor and, similarly, the maximum power densities were found to be 12.5 and 6.5 mW/m2, respectively. MnO2/G catalyst offered an improved MDC performance, however, still with uncompetitive performance in comparison with platinum group metals catalysts.

Anodic metabolic activity regulates the desalination efficiency in microbial catalysed electrochemical system

Anodic metabolic rate showed regulatory influence on the desalination performance of microbial desalination cell (MDC) under open (OC) and closed circuit (CC) operations. In this study, three MDCs were tested for desalination with three different organic substrate loads 1500 ± 55 mg/L in MDC-A; 3500 ± 10 g/L in MDC-B; 4500 ± 12 g/L in MDC-C. Higher desalination and substrate removal rates were observed in CC than OC. Average desalination was MDC-C (51.4%-CC) > MDC-B (47.3%-CC) > MDC-A (45.3%-CC) and COD removal efficiencies were MDC-C (68.4%-CC) > MDC-B (64.4%-CC) > MDC-A (51.9%-CC). Increase in organic load resulted in higher desalination efficiency which was due to higher electrochemical and ionic gradient apart from anodic metabolic activity. The voltage and current density were observed to be maximum in MDC-C (685 mV; 2.16 mA/m2) followed by MDC-B (598 mV; 1.98 mA/m2) and MDC-A (501 mV; 1.76 mA/m2). This study demonstrated that the MDCs performance can be regulated by varying organic load and circuitry modes.