Cathode Chamber Research Articles

Phosphorus Recovery from Whole Digestate through Electrochemical Leaching and Precipitation.

Phosphorus (P) recovery from biosolids can play an important role in a circular economy. Herein, an electrochemical phosphorus recovery cell (EPRC) was proposed and examined to recover P from municipal whole digestate via simultaneous leaching and precipitation. The anode of the EPRC released P as aqueous PO43--P through acidification, achieving the highest leaching efficiency of 93.3% under a current density of 30 A m-2. When the leached P solution was treated in the cathode, native metals including Ca and Fe facilitated electrochemically mediated PO43--P precipitation (EMP) and precipitated ∼99% of the leached P in the cathode chamber. Around 54.3-78.7% of total P existed in two harvestable forms: suspended solids in the cathode effluent and immobilized P in the cathode chamber. The solid products contained 28.42-33.51% of P2O5, comparable to the high-grade phosphate rock. Higher current densities reduced cathode scaling and resulted in a lower content of heavy metals in the solid products. An acidic solution was reused three times and effectively maintained cathode performance during a 42-cycle operation, achieving a consistent P recovery efficiency of nearly 80%. Those results have demonstrated the feasibility of the EPRC for recovering P from P-rich solid wastes.

Study on the performance of anodic desulfurization and cathodic denitrification coupled electricity generation in microbial fuel cell

Sulfide autotrophic denitrification microbial fuel cell was set up and the two reaction processes of desulfurization in anode chamber and denitrification in cathode chamber were separated to study nitrogen and sulfur removal effect and electricity generation capacity. The results showed that simultaneous desulfurization in anode chamber and nitrate removal in cathode chamber was feasible. The removal load of sulfide and nitrate almost increased with the increase of their concentrations under the experiment operation conditions. Higher sulfide concentration in a certain range was beneficial to generate electricity. The change of nitrate concentration in the cathode chamber had less effect on sulfide removal efficiency and electricity production performance of microbial fuel cell, which was mainly depended on the influent sulfide concentration in the anode chamber. The maximum sulfide and nitrate removal loads were 0.36 kg∙m−3∙d−1 and 0.07 kg∙m−3∙d−1 respectively, with a maximum power density of 144.03 mW∙m−3. The external resistance affected the quantities and varieties of reaction products in the anode chamber and the cathode chamber. Lower external resistance was beneficial to improve the efficiency of nitrate removal in the cathode chamber. The microbial community structure of the anode chamber in sulfide autotrophic denitrification MFC was similar to that of sulfide autotrophic denitrification SBR, whose main functional bacterial genera were Clostridium, Thiobacillus and Rhodobacteraceae. However, the functional bacteria in the cathode chamber were completely different, whose dominant bacteria included Thiobacillus, Bacillus, Flavobacteriaceae, Acinetobacter, Sphingomonas and Paracoccus. The research results provided a new idea and method for the sulfur- and nitrogen-containing wastewater treatment.

An electrolytic bubble column with an external hollow fiber membrane gas–liquid contactor for effective microbial electrosynthesis of acetate from CO2

Currently, almost all microbial electrosynthesis (MES) reactors were biofilm-driven whether the cathode electron transfer was direct or indirect. It has been proven that cathode biofilm formation is time-consuming, and the current density achieved on these biofilms was relatively low. However, the main challenge for the non-biofilm-driven MES is how to maintain a good Columbic efficiency (CE) at high current densities. Here, we report a novel electro-H2 bubble column reactor with an external hollow fiber membrane gas–liquid contactor to tackle the challenge. The electrolyzer was placed at the bottom of the reactor to produce H2 micro-bubbles (mean diameter 169 ± 7 µm) at a current density of 156 A/m2. The bubble column was put on the top of the cathodic chamber of the electrolyzer to extend the H2 retention time, while the hollow fiber membrane gas–liquid contactor in the external loop was used to recover the unused gas. Consequently, the homoacetogens in reactor could efficiently convert the electrolytically-produced H2 and the externally-supplied CO2 into acetate. The volume of the catholyte (5.5 L) in this reactor is one order of magnitude higher than all reported MES reactors. Batch tests with enriched homoacetogens demonstrated a maximum acetate production rate (1.15 g/Lcatholyte/d, 898 g/m2cathode/d), acetate titer (34.5 g/L) could be achieved in this setup, and the average (maximum) CE of the electron to acetate efficiency was 64% (92%). Besides, dissolved H2 measurement and bacteria community analysis indicated the high acetate titers were likely caused by the H2 oversaturation situation and good substrate/product mass transfer rather than the selection of certain types of homoacetogens. The electro-H2 bubble reactor seems to be a promising MES setup for scale-up and practical application.

Aniline Degradation Coupled with Removal and Recovery of the Chemically Bound Nitrogen in a Bioelectrochemical System with a Micro-oxygen Bioanode

Eliminating the environmental impact of aromatic amines in traditional wastewater treatment processes requires more than one unit to allow both removal of organic components and the chemically bound nitrogen (CBN). Herein, we report, for the first time, that a bioelectrochemical system with a micro-oxygen bioanode can be a one-stage process to realize the co-removal of organic carbon and CBN derived from aniline (a mode aromatic amine) as well as recover the CBN as value-added ammonium salt. The micro-oxygen condition in the bioanode chamber was demonstrated to promote current output with aniline as the sole electron donor (0.95 ± 0.07 mA, which was 6.78 times higher compared to the anaerobic condition). Accompanied by the 91.92% degradation of aniline, 75.24% of total nitrogen was found to be simultaneously removed. Thereinto, the 54.87% removal was the fact that the produced ammonium was migrated to the cathode chamber and finally recovered by stripping into a sulfuric acid absorber, while the remaining 20.37% removal was a result of denitrification in the anode chamber. Electron balance analysis revealed that 2.14% and 3.92% of the released electrons during aniline degradation contributed to the ammonium recovery and denitrification, respectively. This study opens an opportunity to treat aromatic amine-bearing wastewater in a more compact and sustainable manner.

Flowable capacitive cathode for efficiency carbon dioxide reduction in photoelectrochemical cell

ABSTRACT Photoelectrochemical (PEC) Cell reduction carbon dioxide (CO2) is a promising avenue for converting CO2 into valuable products. In this work, a flowable electrode with a rotating impeller collector was proposed to enhance the efficiency of the carbon dioxide reduction reaction (CO2RR) in a photoelectrochemical system. Titanium carbide (Ti3C2), with its capacitive properties, serves as a catalyst and is fluidized in the cathode chamber. The frequent contact between the Ti3C2 catalysts and the rotating impeller collector extends the catalytic reaction throughout the catholyte and enhances the efficiency of CO2RR. The feasibility of the design was verified through suspension characterization, CO2 diffusion concentration measurement, capacitance characterization, and experimental factor analysis. The PEC with a flow electrode exhibits CO and CH4 production rates of 1.64 μmol g−1h −1and 9.62 μmol g−1h−1, respectively, which are 3.5 and 7.2 times higher than those of the fixed cathode. The Faradaic efficiency for CH4 reaches 92.4%. Moreover, the collision probability of the flow electrode is 17.7%, which is significantly higher than that of the conventional bubbling fluidized electrode. In addition, the capacitive properties of Ti3C2 particles favor the continuous CO2RR under open circuit conditions, which was verified by an EDS test of Na+. Finally, the operational mechanism of the PEC system is described.

Electricity production by Ochrobactrum-related strain CD-1 and pb2+ removal in dual-chamber microbial fuel cell

<p>Dual-chamber microbial fuel cell (MFC) was constructed to treat heavy metal wastewater (Pb2+ solution). The results showed the maximum voltage, the maximum electric power density and pb2+ removal were 9.6 mV, 371.0 mV/m2 and 52.3% respectively. The effects of different cathode chamber environments on the production potential (V, volts) and Pb2+ removal rate of strained CD-1 were investigated. The results show that when the cathode chamber is soil, the maximum voltage is 8.88mV, and when the cathode chamber is solution, the maximum voltage is 12.11mV. The removal efficiency of heavy metals polluted from near to far from the electrode plate in the soil is 68.9%, 62.1%, 57.5%, and the removal efficiency of heavy metals in the solution is 67.46%. It can be concluded that when the soil is the cathode chamber. The removal rate of local heavy metals was the highest. When the solution was used as a cathode chamber, the average removal rate of heavy metals was the highest. The bacteria, named strain CD-1, as the electricity production bacteria (EPB) used in the dual chamber microbial fuel cell (MFC), was isolated from activate sludge and identified on its morphology, physichemical properties and phylogenetic positions. The results indicated that strain CD-1 was Gram-negative, rod. Oxidase and catalase reactions were positive. Strain CD-1 could use gluconate, lactose, D-fructose, L-Arabinose, D-arabinose, acetate, propionate, butyrate, lactate, sucrose and glucose, not use melibiose, galactose, N-acetylglucosamine, ethanol and glycerol.16S rRNA gene sequences analysis showed that strain CD-1 was most related to Ochrobactrum sp. (AJ245941）with the homology similarities of 98%. Based on the above results, strain CD-1 was belonged to the genus of Ochrobactrum and seemed to represent a novel species.</p>

Current to Biomass: Media Optimization and Strain Selection from Cathode-Associated Microbial Communities in a Two-Chamber Electro-Cultivation Reactor

Cathode-associated microbial communities (caMCs) are the functional key elements in the conversion of excess electrical energy into biomass. In this study, we investigated the development of electrochemical caMCs based on two-chamber microbial electrolytic cells (MECs) after optimization of media composition. Microbial communities obtained from a historical soil sample were inoculated into the cathode chamber of MECs. The inorganic medium with (A) carbon dioxide in air or (B) 100 mM sodium bicarbonate as carbon source was used in the absence of any organic carbon source. After 12 days of operation, the experimental results showed that (1) the bacterial community in group B exhibited lush growth and (2) a single strain TX168 Epilithonimonas bovis isolated from group A indicated electrochemical activity and synthesized large volumes of biomass using sodium bicarbonate. We also analyzed the caMCs of the MECs and reference samples without electro-cultivation using 16S rRNA gene sequencing. The results showed that the caMCs of MECs in groups A and B were dominated by the genera Acinetobacter and Pseudomonas. The caMCs were further inoculated and cultured on different agars to isolate specific electroactive bacterial strains. Overall, our study highlights the possibility of converting excess energy into biomass by electro-cultivation and the importance of selecting appropriate media to enrich specific microbial communities and single strains in MECs.

CMOS-compatible electrochemical nanoimprint: High throughput fabrication of ordered microstructures on semiconductor wafer by using a glassy carbon mold

Metal assisted chemical etching (MACE), as an emerging wet chemical etching method for fabricating semiconductor micro/nano-structures (MNS), has attracted wide attentions because of the advantages of simple processes, high accuracy and no damages. However, the conventionally used noble metal catalysts (such as Au, Pt,) trapped in the micro/nano-structures are difficult to be removed or reused, not only harming the electronic performances of the CMOS devices but also increasing the fabrication cost. Here, we propose an electrochemical nanoimprint strategy by using a glassy carbon (GC) imprint mold. To overcome the poor electrocatalytic activity of GC, the GC imprint mold was connected to a Pt sheet in the cathodic chamber. To avoid the contaminations of metal and metallic cations in the fabricated MNS, the cathodic chamber was separated from the anodic one by a proton exchange membrane. By optimizing the technical parameters, including the contact pressure between GC imprint mold and GaAs wafer, the concentration of electron acceptor in the cathodic chamber, the imprinting time, etc., a remarkable corrosion rate of about 130 nm/min was achieved, comparable with that of platinum electrocatalyst. Furthermore, by using a GC imprint mold in the spatially separated corrosion cell, the contaminations caused by both the metal catalysts and metallic ions can be eliminated. Thus, this work provides a potential approach to the high throughput fabrication of CMOS-compatible semiconductor microdevices.

Physico-chemical and rheological properties of meat pates with corn starch suspensions prepared on electrochemically activated water

Introduction. The aim of the study was to determine the influence of electrochemically activated water application on the rheological properties of corn starch suspensions and pates prepared with them. Materials and methods. Corn starch suspensions were prepared on artesian water, which was activated by electrochemical treatment on a diaphragm electrolyzer. Physico-chemical characteristics of electrochemically activated water were determined using a Palintest 7500 photometer. Morphological studies of starch granules were carried out by scanning electron microscopy, and granulometric composition was determined by laser diffraction method. The rheological indicatorss of starch suspensions and pates were studied using a Kinexus Pro+ rheometer. Results and discussion. The physico-chemical characteristics of electrochemically activated water except pH met the requirements of the European Parliament and Council Directive on the quality of water intended for human consumption. The water absorption capacity of starch when preparing its suspensions on a catholyte (obtained by passing a direct electric current through water in the cathode chamber of an electrolyzer) decreased by 26%, and when prepared on an anolyte (obtained in the process of water oxidation reactions on the anode) increased by 18%. The moisture holding capacity of hydrated starch decreased by 10% when using catholyte, and increased by 36% when using anolyte. Electrochemically activated water had a significant effect on the rheological characteristics of starch suspensions: with an increase in the percentage of complex shear strain, the shear stress increased proportionally for samples of suspensions made on electrochemically activated water. The viscoelastic properties of starch suspensions prepared using electrochemically activated water both at 25 ℃ and at 68 ℃ tended towards an ideally elastic gel, that is, they had more elastic structure than the control samples. Under the action of shear deformation, the elastic properties were lost, while the suspensions acquired viscosity (phase angle values increased). The maximum value of the moisture binding capacity of pates was observed when using a starch suspension prepared on anolyte. The best values of rheological characteristics of pates were obtained when using starch suspension with 2% starch prepared on anolyte. Conclusions. Electrochemically activated water had a significant effect on the physicochemical and rheological properties of semi-finished products, in particular corn starch suspensions, and pates prepared with them, and contributed to better structuring of the studied food systems.

Copper recovery from printed circuit boards leaching solution with bioelectricity generation using microbial fuel cell

Recovery of valuable metals via leaching printed circuit boards (PCBs) has gained moment recently. This work studied the Microbial fuel cell (MFC) performances for recovery of Cu from a Cu2+ solution by examining key operating parameters. A dual-chamber MFC with 6cm × 6cm × 7cm dimensions was constructed. Both anode and cathode electrodes were made of a carbon cloth sheet. The anodic and cathodic chambers were separated by a Nafion membrane. The highest Cu recovery efficiency was 99.7% after 240h batch mode operation, yielding 102 mW/m2 MFC power density output using 1g/L Cu2+ solution as the catholyte (initial pH 3) and an anolyte containing 1g/L sodium acetate inoculated with a sludge from a wastewater treatment plant's anaerobic pond, with 2cm distance between the electrodes made of polyacrylonitrile polymer. The highest open circuit voltage, current density (based on cross-section cathode area) and power density with an external load of 1 kΩ was 555mV, 347mA/m2 and 193 mW/m2, respectively. Additionally, recovery of Cu in the leachate of PCBs using sulfuric acid leaching after 48h was performed and the highest Cu recovery was 50% in 48h.

Influences of cathode potential and carbon source on parabromoaniline degradation in microbial electrolysis cell

AbstractA microbial electrolysis cell was established to explore the degradation characteristics of characteristic pollutants in wastewater for parabromoaniline (P‐BrA). Their effects on P‐BrA reduction and degradation were investigated through factors such as impressed voltage and cosubstrate type. The P‐BrA residue and degradation in wastewater were analysed quantitatively through analytical testing methods, such as ultraviolet–visible, cyclic voltammetry, high‐performance liquid chromatograph, and scanning electron microscopy. The results showed that under the cathode potential of 0.5 V, electrons and electroactive microorganisms generate coupling action to accelerate the degradation of P‐BrA, reaching 94.94%. Moreover, the addition of carbon source organisms, such as glucose and sodium acetate, can facilitate the degradation of P‐BrA in the cathode chamber on the precondition that the electroactive anaerobic microbial C/N ratio was satisfied, both reaching over 90%. In addition, the microbial community diversity and richness of bioelectrochemistry system were enhanced after bioaugmentation. The increase in the Anacrolincalcs, Betaproteobacteriales, and Micrococcales also played an important role in the granulation of bioelectrochemistry system and the removal of characteristic pollutants.

Regulating the electrokinetic delivery of Tween 80 and persulfate for remediating low-permeability phenanthrene contaminated soil: Importance of reducing unproductive consumption

Controllable delivery of persulfate (PS) and the enhancement of oxidative availability of pollutants in in-situ oxidative remediation of low-permeability polycyclic aromatic hydrocarbons (PAHs) contaminated soil are crucial. To tackle the above challenges, the coupling of Tween 80 solubilization enhanced oxidation of phenanthrene (PHE) in low-permeability soil under electrokinetic remediation (EKR) was proposed. Firstly, batch degradation experiments showed that the addition of Tween 80 significantly inhibited the degradation of PHE in soil under thermally activated PS, as the dosage of Tween 80 increased from 0 % to 1 % with the corresponding removal rate declining from 99.19 % to 40.90 %. Accordingly, in-situ electrokinetic delivery of Tween 80 and PS was regulated in further EKR, intending to reduce unproductive consumption. PS was more uniformly delivered to the whole remediation regions from the cathode chamber by electromigration, while Tween 80 was transported into the soil from the anode chamber by electroosmosis, which made Tween 80 solubilization and PS oxidation achieve synergistic effect. And the total removal rate of PHE reached 64.90 % under this strategy, which had increased by 415.90 % and 8.76 %− 130.14 % compared with only EKR or EKR coupling single enhanced technology, respectively. After further thermal activation of transported PS at 50 ℃ by electrical resistance heating, the total removal rate of PHE increased to 71.58 %. EPR spectrum indicated that SO4.- and OH. were responsible for the degradation of PHE.

Biochar based cathode enriched with hydroxyapatite and Cu nanoparticles boosting electromethanogenesis

Electromethanogenesis is an innovative technology addressing the need of storing renewable energy from unprogrammable sources. It allows for the electrochemical production of methane from CO2-rich wastes on microbial cathodes, in a logic of power-to-gas (BEP2G). The challenge of cost-effective and sustainable biocathodes enhancing the microorganism performance and yield of electromethanogenesis is approached in this work. For the first time, porous carbonaceous cathodes were functionalized with Cu nanoparticles and hydroxyapatite (HAP) and successfully experimented for supporting microbial CO2 reduction reaction (CO2RR) to methane. Tests were performed in a double chamber system under CO2 flow at 45 °C. Next Generation Sequencing of 16S RNA indicated that the microbial pool on the cathodes was mostly enriched in Metanobacteriaceae (hydrogenotrophic Archaea) and different fermenting bacteria, depending on the cathode type. High methane production on cathodes made of Cu 20%, HAP 10%, and carbon balance (20Cu/10HAP) was achieved, with a maximum of 866 ± 199 mmol m−2 d−1 (projected cathode area, Coulombic efficiency of 64%), corresponding to values comparable to the maximum in literature, but in shorter timespans (8 vs. 30 days). The documented effect of pH stabilization in the cathodic chamber by HAP was one of the main parameters that concurred to the selectivity of CO2RR towards methane.

Wastewater Treatment and Electricity Generation with Different Cathode Solutions in MFC

A microbial fuel cell (MFC) with cathode and anode chambers was utilized to generate power while simultaneously removing COD from wastewater. By utilizing various oxidant solutions, it is possible to increase the generated voltage. The anode chamber was used for anaerobic treatment of synthetic wastewater (approximately 1000 mg/L), whereas the cathode chamber contained various oxidant solutions such as dilute hydrogen peroxide (300 mg/L), KMnO4 (300 mg/L), K2Cr2O7 (300 mg/L) and Fenton reagent (H2O2/Fe(II), 300/20 mg/L). Aerobic wastewater treatment and intermittent ozonation were also tested in the cathode chamber. With intermittent ozonation of the cathode chamber, the highest power output (382 mW/m2) was obtained. At the conclusion of the operation period, the COD concentration in the anode chamber decreased from 1170 mg/L to 650 mg/L, resulting in nearly 45% COD removal. In the cathode chamber, the use of diluted KMnO4 and H2O2 solutions produced high power densities of 35 and 23 W/m2, respectively, while the other oxidants produced low power densities. At the end of 72 hours, the COD content of the anaerobic chamber decreased from 800 mg/L to nearly 333 mg/L, resulting in nearly 59% COD removal for the KMnO4 solution. Considering the high cost of ozonation, it is recommended that either aerobic wastewater treatment or dilute KMnO4/H2O2 solutions should be used in the cathode chamber for high power generation.

Removal of chloramphenicol and resistance gene changes in electric-integrated vertical flow constructed wetlands

The performance of an electric-integrated vertical flow constructed wetland (E-VFCW) for chloramphenicol (CAP) removal, changes in microbial community structure, and the fate of antibiotic resistance genes (ARGs) were evaluated. CAP removal in the E-VFCW system was 92.73% ± 0.78% (planted) and 90.80% ± 0.61% (unplanted), both were higher than the control system which was 68.17% ± 1.27%. The contribution of anaerobic cathodic chambers in CAP removal was higher than the aerobic anodic chambers. Plant physiochemical indicators in the reactor revealed electrical stimulation increased oxidase activity. Electrical stimulation enhanced the enrichment of ARGs in the electrode layer of the E-VFCW system (except floR). Plant ARGs and intI1 levels were higher in the E-VFCW than in the control system, suggesting electrical stimulation induces plants to absorb ARGs, reducing ARGs in the wetland. The distribution of intI1 and sul1 genes in plants suggests that horizontal transfer may be the main mechanism dispersing ARGs in plants. High throughput sequencing analysis revealed electrical stimulation selectively enriched CAP degrading functional bacteria (Geobacter and Trichlorobacter). Quantitative correlation analysis between bacterial communities and ARGs confirmed the abundance of ARGs relates to the distribution of potential hosts and mobile genetic elements (intI1). E-VFCW is effective in treating antibiotic wastewater, however ARGs potentially accumulate.

Parametric Optimization and performance assessment of polyaniline graphene-impregnated electrode-based low-cost Microbial Fuel Cell using mixed culture obtained from Canteen wastewater

The development of a high-efficiency anode is essential for the use of microbial fuel cells. The metallic conductivity, corrosion resilience, low cost of conducting polyaniline (PANI) and recycled graphene (RGn) pique our interest. In this study, PANI-RGn nanoparticles are polymerized in situ on cotton fabric wrapped with aluminium mesh as the anode for a microbial fuel cell. The MFC was designed as a dual-chambered system and the chambers are separated by a proton exchange membrane (PEM) salt bridge using canteen wastewater. The process parameters including cathodic chamber aeration, nutrient dosage, nitrogen fluxing, stirring and anode geometry, were optimized. The potential difference (mV) and these systems' current (mA) performance have been analyzed. On the use of PANI-RGn carbon cloth as electrodes, the output voltage was found to be of the order of 180mV. The system developed herewith is highly cost-effective because of the use of graphene that has been generated from waste plastic through catalytic pyrolysis. Hence, the present study revealed that a potential green energy alternative is PANI-RGn in situ polymerized cotton fabric and circular aluminium-mesh electrode in anoxic MFC.

Utilization of Electrodeionization for Lithium Removal.

In this work, usage of a hybrid polymeric ion exchange resin and a polymeric ion exchange membrane in the same unit to remove Li+ from aqueous solutions was reported. The effects of the applied potential difference to the electrodes, the flow rate of the Li-containing solution, the presence of coexisting ions (Na+, K+, Ca2+, Ba2+, and Mg2+), and the influence of the electrolyte concentration in the anode and cathode chambers on Li+ removal were investigated. At 20 V, 99% of Li+ was removed from the Li-containing solution. In addition, a decrease in the flow rate of the Li-containing solution from 2 to 1 L/h resulted in a decrease in the removal rate from 99 to 94%. Similar results were obtained when the concentration of Na2SO4 was decreased from 0.01 to 0.005 M. The selectivity test showed that the simultaneous presence of monovalent ions such as Na+ and K+ did not change the removal rate of Li+. However, the presence of divalent ions, Ca2+, Mg2+, and Ba2+, reduced the removal rate of Li+. Under optimal conditions, the mass transport coefficient of Li+ was found as 5.39 × 10-4 m/s, and the specific energy consumption was found as 106.2 W h/g LiCl. Electrodeionization provided stable performance in terms of the removal rate and transport of Li+ from the central compartment to the cathode compartment.

Evaluation of the respective contribution of anode and cathode for triclosan degradation in a bioelectrochemical system

In this work, the bioelectrochemical system (BES) is a feasible alternative for successfully degrading typical refractory emerging contaminant triclosan (TCS). A single-chamber BES reactor with an initial TCS concentration of 1 mg/L, an applied voltage of 0.8 V, and a solution buffered with 50 mM PBS degraded 81.4 ± 0.2% of TCS, exhibiting TCS degradation efficiency improvement to 90.6 ± 0.2% with a biocathode formed from a reversed bioanode. Both bioanode and biocathode were able to degrade TCS with comparable efficiencies of 80.8 ± 4.9% and 87.3 ± 0.4%, respectively. Dechlorination and hydrolysis were proposed as the TCS degradation pathway in the cathode chamber, and another hydroxylation pathway was exclusive in the anode chamber. Microbial community structure analysis indicated Propionibacteriaceae was the predominant member in all electrode biofilms, and the exoelectrogen Geobacter was enriched in anode biofilms. This study comprehensively revealed the feasibility of operating BES technology for TCS degradation.

Feasibility of a self‐sustaining microbial fuel cell incorporating natural processes of bacteria and microalgae towards a circular bioeconomy

AbstractA microbial fuel cell (MFC) consisting of a bacterial anode chamber and a microalgal cathode chamber was operated under various conditions to assess its technical feasibility. Maximum achievable power density reached up to 7.13 mW m–2. The traditional MFC process of conversion of carbon sources to bioelectricity in the anodic chamber was compared with a system circulating anodic effluent to the cathode chamber. The bacteria and microalgae simultaneously carried out the carbon recycling and recovery of energy and resources synergizing the performance of MFC. Results indicated a comparable chemical oxygen demand removal efficiencies at 50% of the retention time compared to the traditional system. The dissolved oxygen concentration varied between 11.95 and 7.44 mg L–1 with Chlorella vulgaris under alternative light and dark cycles. Despite the variations in electricity output, the system showed its technical feasibility to harness energy for photosynthesis under natural sunlight conditions.

Unravelling and enhancing the power recovery and nitrogen removal mechanism from wastewater by isolating input nitrogen in a coupled microbial fuel cell system

Poor recovery energy of microbial fuel cells (MFCs) persists and is considerably lower when dealing with nitrogen, a substantial challenge of this technology. This study investigated power generation from treating different COD/N ratio wastewater by isolating the input nitrogen using the coupled MFC system, including nitrification-MFC (N-MFC) and denitrification-MFC (D-MFC). Energy from wastewater was predominantly recovered in the N-MFC due to the system's configuration, which allowed for the oxidation of over 75% of organic matter input while simultaneously isolating nitrogen input. The nitrogen isolation was affected by the electricity generation of the N-MFC. The complete nitrification was done in the first mode under dissolved oxygen (DO) of 4 mg L−1 in the cathode chamber of the N-MFC. When the DO was decreased to 0.6 mg L−1 in the second mode, over 95% of the ammonium was oxidized to nitrite and nitrate in a 2:1 ratio. The N-MFC's power density of 6.16–6.3 W m−3 was achieved in the first mode, while a power generation of 0.82 W m−3 was obtained in the second mode. The principal mechanism for nitrogen removal at the D-MFC was autotrophic denitrification. The first mode nitrogen removal efficiency was 56.9%, 72.7%, and 80.2% for COD/N input of 5.5, 7.1, and 10.3, respectively. The second mode utilized the short-cut nitrification-denitrification process, superior to the first mode with regards to energy efficiency and nitrogen removal. However, the usage of CEM as separator and aeration requirement makes this technology expensive. Results indicated that nitrogen removal and effective utilization of organic matter for energy recovery could be achieved with a proper configuration for a coupled MFC and in future the cost can be reduced.