Jiaqi Ren, Gaoming Wu, Zheng Xia et al.

AIChE Journal • 2021

<jats:title>Abstract</jats:title><jats:p>Low organic carbon‐to‐nitrogen ratio and existing sulfate (SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup>) in industrial wastewater limited nitrogen removal. Coupling SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup> reduction with sulfide autotrophic denitrification provides a novel strategy. Herein, bioelectrochemical sulfate reduction was coupled with heterotrophic sulfate reduction to drive sulfide autotrophic denitrification. In this coupled system, total nitrogen (TN) removal efficiency was increased from ~25% to ~85% by inputting −45 mA electricity. With the help of supplying electrons to denitrification through SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup> reduction, coulomb efficiency was improved to 61.5%. Also, bioelectrochemical sulfate reduction could improve sulfur recovery and thus increase TN removal efficiency. Furthermore, through tuning turnover numbers of SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup>, high TN removal efficiency can be obtained at various concentrations of SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup>. Moreover, main functional bacteria in this system were identified. Finally, ~75% TN removal efficiency was achieved with real wastewater in this system. Overall, this work offered a new approach for efficient nitrogen removal from industrial wastewater containing SO<jats:sub>4</jats:sub><jats:sup>2−</jats:sup>.</jats:p>

Joanna Rodziewicz, Artur Mielcarek, Kamil Bryszewski et al.

Energies • 0

<jats:p>An attempt was undertaken to determine indicators of energy consumption in bio-electro reactors (BERs) i.e., an aerobic rotating electrobiological disc contactor (REBDC) and an anaerobic sequencing batch biofilm reactor (SBBR), during contaminant removal from soilless tomato cultivation wastewater having a specific composition, i.e., high nitrate and phosphorus concentrations and low COD. Because of this specificity, the energy consumption during the treatment process was characterized by a cumulative indicator for simultaneous removal of phosphorus and nitrates—EEINUTRIENTSrem (electric energy consumption per unit of removed nutrient load, expressed as kWh/kgNUTRIENTSrem). Four values of direct current density were tested: 0.63, 1.25, 2.5, and 5.0 A/m2. The indicator values were compared at a hydraulic retention time (HRT) of 24 h. The study demonstrated that the values of electric energy consumption per unit of removed nutrient load determined in the anaerobic SBBR ranged from 30 to 464 kWh/kg NUTRIENTSrem and were lower than the values obtained in the aerobic REBCD, i.e., 80–1380 kWh/kg NUTRIENTSrem.</jats:p>

Wenjuan Zhao, YiZhao Gao, Yongli Zhao et al.

Biotechnology and Bioengineering • 2022

<jats:title>Abstract</jats:title><jats:p>Generally, high bioelectroactivity of anodophilic biofilm favors high power generation of microbial fuel cell (MFC); however, it is not clear whether it can promote denitrification of MFC synchronously. In this study, we studied the impact of anodophilic biofilm bioelectroactivity on the denitrification behavior of air‐cathode MFC (AC‐MFC) in steady state and found that high bioelectroactivity of anodophilic biofilm not only favored high power generation of the AC‐MFC, but also promoted the growth of denitrifers at the anodes and strengthened denitrification. Anodophilic biofilms of AC‐MFC with various bioelectroactivity were acclimated at conditions of open circuit (OC), <jats:italic>R</jats:italic><jats:sub>ext</jats:sub> of 1000 Ω and 20 Ω (denoted as AC‐MFC‐OC, AC‐MFC‐1000Ω, and AC‐MFC‐20Ω, respectively) and performed for over 100 days. Electrochemical tests and microbial analysis results showed that the anode of the AC‐MFC‐20Ω delivered higher current response of both oxidation and denitrification and had higher abundance of electroactive bacteria than the AC‐MFC‐OC, AC‐MFC‐1000Ω, demonstrating a higher bioelectroactivity of the anodophilic biofilms. Moreover, these electroactive bacteria favored the accumulation of denitrifers, like <jats:italic>Thauera</jats:italic> and <jats:italic>Alicycliphilus</jats:italic>, probably by consuming trace oxygen through catalyzing oxygen reduction. The AC‐MFC‐20Ω not only delivered a 61.7% higher power than the AC‐MFC‐1000Ω, but also achieved a stable and high denitrification rate constant <jats:italic>(k</jats:italic><jats:sub>DN</jats:sub>) of 1.9 h<jats:sup>−1</jats:sup>, which was 50% and 40% higher than that of the AC‐MFC‐OC and AC‐MFC‐1000Ω, respectively. It could be concluded that the high bioelectroactivity of the anodophilic biofilms not only favored high power generation of the AC‐MFC, but also promoted the enrichment of denitrifers at the anodes and strengthened denitrification. This study provided an effective method for enhancing power generation and denitrification performance of the AC‐MFC synchronously.</jats:p>

Anup Gurung, Bhim Sen Thapa, Seong-Yun Ko et al.

Energies • 0

<jats:p>Nitrate (NO3−-N) and nitrites (NO2−-N) are common pollutants in various water bodies causing serious threats not only to aquatic, but also to animals and human beings. In this study, we developed a strategy for efficiently reducing nitrates in microbial fuel cells (MFCs) powered by a granular activated carbon (GAC)-biocathode. GAC was developed by acclimatizing and enriching denitrifying bacteria under a redox potential (0.3 V) generated from MFCs. Thus, using the formed GAC-biocathode we continued to study their effect on denitrification with different cathode materials and circulation speeds in MFCs. The GAC-biocathode with its excellent capacitive property can actively reduce nitrate for over thirty days irrespective of the cathode material used. The stirring speed of GAC in the cathode showed a steady growth in potential generation from 0.25 V to 0.33 V. A rapid lag phase was observed when a new carbon cathode was used with enriched GAC. While a slow lag phase was seen when a stainless-steel cathode was replaced. These observations showed that effective storage and supply of electrons to the GAC plays a crucial role in the reduction process in MFCs. Electrochemical analysis of the GAC properties studied using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and zeta potential showed distinct properties with different abiotic and biocathode conditions. We found that the enrichment of electrotrophic bacteria on GAC facilitates the direct electron transfer in the cathode chamber for reducing NO3−-N in MFCs as observed by scanning electron microscopy.</jats:p>

Rui He, Lifen Liu, Peng Shi et al.

Journal of Chemical Technology &amp; Biotechnology • 2018

<jats:title>Abstract</jats:title><jats:sec><jats:title>BACKGROUND</jats:title><jats:p>To decontaminate sites of pollutants, fuel cell and bio‐electrochemical fuel cell reactors can degrade pollutants and generate electricity simultaneously, potentially decrease cost, energy consumptions and treatment cycle. In this study, a photocatalytic fuel cell (PFC) and PEC‐MFC (integrated photo‐electro‐catalysis with microbial fuel cell) were investigated to decontaminate sand/water polluted by RhB, antibiotics and heavy metal ions.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>In the PFC, paired electrodes with ZnIn<jats:sub>2</jats:sub>S<jats:sub>4</jats:sub>‐AgAgCl/GO or ZnIn<jats:sub>2</jats:sub>S<jats:sub>4</jats:sub>‐RGO/MnO<jats:sub>2</jats:sub>, effectively removed pollutants in sand/water. The removal of RhB was 95.6% in 100 min with an external resistance of 1 Ω under aeration. Adding cyclo‐dextrin increased pollutant removals, realized 66% removal of RhB in overlying water, and significant removal in sand after 5 h, and 70% removal of tetracycline in overlying water, but only 60% without cyclodextrin after 4 h. Adding KMnO<jats:sub>4</jats:sub> and NaHSO<jats:sub>3</jats:sub> promoted decontamination of tetracycline from sand/water, tetracycline in water was almost completely degraded in 3.5 h with the addition, but only about 65% without any addition. In the PEC‐MFC, integrating photo‐electro‐catalytic electrode with bio‐anode, Cr(VI) in the cathode chamber was reduced rapidly and the concentration of RhB in sand decreased quickly, nearly complete in 2 h. The Cr(VI) in sand was reduced in several hours, so that, compared with previous reports, the treatment time is significantly shortened.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSION</jats:title><jats:p>The PFC and PEC‐MFC systems are successful in decontaminating sand/water in polluted sites and are cost‐effective and sustainable methods. By building an on‐site or off‐site system with washing and cycling of the liquid stream, it could be a convenient remediation method for polluted sites. © 2018 Society of Chemical Industry</jats:p></jats:sec>

Sara Cangussú Bassoli, Matheus Henrique Alcântara de Lima Cardozo, Fabiano Luiz Naves et al.

Fermentation • 0

<jats:p>Microalgal biomass contributes to the valorization of urban and agro-industrial solid waste via hydrothermal co-liquefaction (co-HTL) for the production of biocrude, a sustainable substitute for petroleum. Tropical and populous countries like Brazil generate a lot of agro-industrial waste, such as sugarcane bagasse and malt bagasse, as well as sludge from sewage treatment plants. Such residues are potential sources of biocrude production via thermochemical conversion. To increase biocrude productivity, microalgal biomass has been successfully used in mixing the co-HTL process feed with different residues. In addition to biocrude, co-HTL generates an aqueous phase that can be used to produce H2 and/or electricity via microbial energy cells. In this sense, this paper aims to present the potential for generating energy from solid waste commonly generated in emerging countries such as Brazil based on a simplified scheme of a conceptual biorefinery employing algal biomass co-HTL together with sugarcane bagasse, malt bagasse, and sludge. The biorefinery model could be integrated into an ethanol production plant, a brewery, or a sewage treatment plant, aiming at the production of biocrude and H2 and/or electricity by bioelectrochemical systems, such as microbial electrolysis cells and microbial fuel cells.</jats:p>

D. Carrillo-Peña, A. Escapa, M. Hijosa-Valsero et al.

Biomass Conversion and Biorefinery • 2024

<jats:title>Abstract </jats:title><jats:p>A microbial electrolysis cell integrated in an anaerobic digestion system (MEC-AD) is an efficient configuration to produce methane from an exhausted vine shoot fermentation broth (EVS). The cell worked in a single-chamber two-electrode configuration at an applied potential of 1 V with a feeding ratio of 30/70 (30% EVS to 70% synthetic medium). In addition, an identical cell operated in an open circuit was used as a control reactor. Experimental results showed similar behavior in terms of carbon removal (70–76%), while the specific averaged methane production from cycle 7 was more stable and higher in the connected cell (MEC<jats:sub>AD</jats:sub>) compared with the unpolarized one (OC<jats:sub>AD</jats:sub>) accounting for 403.7 ± 33.6 L CH<jats:sub>4</jats:sub>·kg VS<jats:sup>−1</jats:sup> and 121.3 ± 49.7 L CH<jats:sub>4</jats:sub>·kg VS<jats:sup>−1</jats:sup>, respectively. In addition, electrochemical impedance spectroscopy revealed that the electrical capacitance of the bioanode in MEC<jats:sub>AD</jats:sub> was twice the capacitance shown by OC<jats:sub>AD</jats:sub>. The bacterial community in both cells was similar but a clear adaptation of <jats:italic>Methanosarcina</jats:italic> Archaea was exhibited in MEC<jats:sub>AD</jats:sub>, which could explain the increased yields in CH<jats:sub>4</jats:sub> production. In summary, the results reported here confirm the advantages of integrating MEC-AD for the treatment of real organic liquid waste instead of traditional AD treatment.</jats:p>

René Cardeña, Iván Moreno‐Andrade, Germán Buitrón

Journal of Chemical Technology &amp; Biotechnology • 2018

<jats:title>Abstract</jats:title><jats:sec><jats:title>BACKGROUND</jats:title><jats:p>Food waste is a valuable source of hydrogen by dark fermentation. Dark fermentation effluent contains volatile fatty acids that can be further converted into more hydrogen using microbial electrolysis cells (MECs). In this process, the anodic potential (<jats:italic>E<jats:sub>an</jats:sub></jats:italic>) has a significant influence on the MEC performance as well as the effluent composition. The objective of this study was to evaluate the effects of variation of the anode potential and substrate composition (food waste fermentation effluent) on the performance of hydrogen production using two‐chamber MECs.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Colonization was conducted using an <jats:italic>E<jats:sub>an</jats:sub></jats:italic> of 0.5 V vs Ag/AgCl. After 38 days, the <jats:italic>E<jats:sub>an</jats:sub></jats:italic> had decreased to 0.3 V, resulting in an increase in the hydrogen production rate (from 287 to 482 mL H<jats:sub>2</jats:sub> L<jats:sup>‐1</jats:sup><jats:sub>cat</jats:sub> d<jats:sup>‐1</jats:sup>). A maximum hydrogen production rate of 685 mL H<jats:sub>2</jats:sub> L<jats:sup>‐1</jats:sup><jats:sub>cat</jats:sub> d<jats:sup>‐1</jats:sup> was observed when effluent that contained the highest acetate concentration was utilized. Cathodic hydrogen recovery was higher than 93%, and hydrogen yield was greater than 873 mL H<jats:sub>2</jats:sub> g<jats:sup>‐1</jats:sup> COD.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSION</jats:title><jats:p>The start‐up strategy in which <jats:italic>E<jats:sub>an</jats:sub></jats:italic> is decreased after the formation of an electroactive biofilm resulted in increased hydrogen production. The composition of the food waste fermented effluent influences the hydrogen production rate. © 2017 Society of Chemical Industry</jats:p></jats:sec>

Noémi N. Horváth-Gönczi, Zoltán Bagi, Márk Szuhaj et al.

Fermentation • 0

<jats:p>Bioelectrochemical systems (BESs) have great potential in renewable energy production technologies. BES can generate electricity via Microbial Fuel Cell (MFC) or use electric current to synthesize valuable commodities in Microbial Electrolysis Cells (MECs). Various reactor configurations and operational protocols are increasing rapidly, although industrial-scale operation still faces difficulties. This article reviews the recent BES related to literature, with special attention to electrosynthesis and the most promising reactor configurations. We also attempted to clarify the numerous definitions proposed for BESs. The main components of BES are highlighted. Although the comparison of the various fermentation systems is, we collected useful and generally applicable operational parameters to be used for comparative studies. A brief overview links the appropriate microbes to the optimal reactor design.</jats:p>

Néstor Isidro Rincón-Catalán, Abumalé Cruz-Salomón, P.J. Sebastian et al.

Processes • 0

<jats:p>Banana is the most cultivated fruit plant in the world. It is produced in Latin America, Asia and Africa. India and China are the world’s largest banana producers, with almost 41% of the world’s production. This fruit reaches a total world production of 158.3 million tons per year. However, during their production cycle, the banana agroindustry produces large volumes of solid waste derived from overripe fruit. It contributes between 8–20 percent of the waste (around 100 kg of banana waste for every ton of banana produced). Therefore, the use of overripe banana waste represents a huge opportunity for bioenergy production. This work demonstrates that banana waste can be further used for power generation using a microbial fuel cell (MFC) coupled with anaerobic digestion (AD). First, the maximum methane production (MMP), methane production rate (MPR) and biochemical methane potential (BMP) were measured using an anaerobic batch bioreactor for 64 days of monitoring. Finally, the digestate generated from AD was used in the MFC to determine the polarization curve, maximum voltage, maximum power density (MPD), resistance and current. As a result, the AD generated an MMP of 320.3 mL, BMP of 373.3 mLCH4/gVS and MPR of 18.6 mLCH4/Lb⋅day. The MFC generated 286 mV (maximum voltage), 41.3 mW/m2 (MPD), 580.99 Ω (resistance) and 0.0002867 A (current). Both processes together produced a total bioenergy of 13.38 kJ/gVS. This coupled system showed a suitable and promising use of banana waste for ecofriendly bioenergy generation. Therefore, this feedstock could be taken advantage of for generating sustainable processes and developing a circular economy in the banana agroindustry.</jats:p>

Shixiang Dai, Benjamin Korth, Carsten Vogt et al.

Frontiers in Chemical Engineering • 0

<jats:p>Hydrothermal carbonization (HTC) is a promising technology for chemical and material synthesis. However, HTC produces not only valuable solid coal-materials but also yields process water (PW) with high chemical oxygen demand (COD) that requires extensive treatment. Anaerobic digestion (AD) has been used for initial treatment of HTC-PW, but the AD effluent is still high in COD and particles. Here, we show that microbial electrochemical technologies (MET) can be applied for COD removal from AD effluent of HTC-PW. Bioelectrochemical systems (BES) treating different shares of AD effluent from HTC-PW exhibited similar trends for current production. Thereby, maximum current densities of 0.24 mA cm<jats:sup>−2</jats:sup> and COD removal of 65.4 ± 4.4% were reached (<jats:italic>n</jats:italic> = 3). Microbial community analysis showed that the genus <jats:italic>Geobacter</jats:italic> dominated anode biofilm and liquid phase of all reactors indicating its central role for COD oxidation and current generation.</jats:p>

Qing Zhao, Hairong Yuan, Xiujin Li

Processes • 0

<jats:p>This study aims to investigate the effect of different applied voltages on the biomethanation performance and microbial community characteristics of corn stover (CS) in a microbial electrolysis cell (MEC)-assisted anaerobic digestion (AD) system (MEC-AD). The results showed that the MEC-AD system operating at 0.8 V achieved the highest methane yield of 192.40 mL CH4/g VS (volatile solids), an increase of 14.98% compared to the conventional AD. The system obtained methane yields of 187.74 to 191.18 mL CH4/g VS at lower voltages (0.4 V and 0.6 V), and 156.11–182.75 mL CH4/g VS at higher voltages (1.0 V and 1.2 V), respectively, suggesting that lower or higher voltages would have adversely impacted the methane yield. Correspondingly, the MEC-AD system operating at 0.4–0.8 V achieved over 71.47% conversion rates of total solids (TS), VS, and cellulose. The microbial community analysis revealed that 0.8 V optimally enriched fermentative acidogenic bacteria (FABs, 24.55%) and electroactive bacteria (13.50%), enhancing both hydrolysis acidification efficiency and direct interspecies electron transfer (DIET). Both Methanosarcina and Methanoculleus demonstrated significant positive correlations with FABs, SOBs, and electroactive bacteria. This study reveals that 0.8 V represents the optimal operating voltage for biomethane production in MEC-AD systems, providing critical insights for agricultural waste valorization.</jats:p>

Nhlanganiso Ivan Madondo, Sudesh Rathilal, Babatunde Femi Bakare et al.

Microorganisms • 0

<jats:p>In this paper, the application of magnetite-nanoparticles and a microbial fuel cell (MFC) was studied on the anaerobic digestion (AD) of sewage sludge. The experimental set-up included six 1 L biochemical methane potential (BMP) tests with different external resistors: (a) 100 Ω, (b) 300 Ω, (c) 500 Ω, (d) 800 Ω, (e) 1000 Ω, and (f) a control with no external resistor. The BMP tests were carried out using digesters with a working volume of 0.8 L fed with 0.5 L substrate, 0.3 L inoculum, and 0.53 g magnetite-nanoparticles. The results suggested that the ultimate biogas generation reached 692.7 mL/g VSfed in the 500 Ω digester, which was substantially greater than the 102.6 mL/g VSfed of the control. The electrochemical efficiency analysis also demonstrated higher coulombic efficiency (81.2%) and maximum power density (30.17 mW/ m2) for the 500 Ω digester. The digester also revealed a higher maximum voltage generation of 0.431 V, which was approximately 12.7 times the 0.034 V of the lowest-performing MFC (100 Ω digester). In terms of contaminants removed, the best-performing digester was the digester with 500 Ω, which reduced contaminants by more than 89% on COD, TS, VS, TSS and color. In terms of cost-benefit analysis, this digester produced the highest annual energy profit (48.22 ZAR/kWh or 3.45 USD/kWh). This infers the application of magnetite-nanoparticles and MFC on the AD of sewage sludge is very promising for biogas production. The digester with an external resistor of 500 Ω showed a high potential for use in bioelectrochemical biogas generation and contaminant removal for sewage sludge.</jats:p>

Chenglong Xu, Jialei Lu, Zhimiao Zhao et al.

Water • 0

<jats:p>An aircathode microbial desalination cell (AMDC) was successfully started by inoculating anaerobic sludge into the anode of a microbial desalination cell and then used to study the effects of salinity on performance of AMDC and effect of treatment of coastal saline-alkaline soil-washing water. The results showed that the desalination cycle and rate gradually shorten, but salt removal gradually increased when the salinity was decreased, and the highest salt removal was 98.00 ± 0.12% at a salinity of 5 g/L. COD removal efficiency was increased with the extension of operation cycle and largest removal efficiency difference was not significant, but the average coulomb efficiency had significant differences under the condition of each salinity. This indicates that salinity conditions have significant influence on salt removal and coulomb efficiency under the combined action of osmotic pressure, electric field action, running time and microbial activity, etc. On the contrary, COD removal effect has no significant differences under the condition of inoculation of the same substrate in the anode chamber. The salt removal reached 99.13 ± 2.1% when the AMDC experiment ended under the condition of washing water of coastal saline-alkaline soil was inserted in the desalination chamber. Under the action of osmotic pressure, ion migration, nitrification and denitrification, NH4+-N and NO3−-N in the washing water of the desalination chamber were removed, and this indicates that the microbial desalination cell can be used to treatment the washing water of coastal saline-alkaline soil. The microbial community and function of the anode electrode biofilm and desalination chamber were analyzed through high-throughput sequencing, and the power generation characteristics, organics degradation and migration and transformation pathways of nitrogen of the aircathode microbial desalination cell were further explained.</jats:p>

Yolanda Ruiz, Juan A Baeza, Nuria Montpart et al.

Journal of Chemical Technology &amp; Biotechnology • 2020

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Cyclic voltammetry (CV) has become a standard tool in the study of bioelectrochemical systems (BES) because it is a nondestructive technique that provides useful information on the electron transfer capacity of these systems. When applied to the large‐surface electrodes typically found in BES, the scan rate must be severely diminished or otherwise the capacitive current masks the faradaic current. Decreasing the scan rate results in an increase in the duration of the experiments, which can lead to a significant alteration of the initial system conditions.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The repeatability of low scan rate cyclic voltammetry (LSCV) in air cathode microbial fuel cells (AC‐MFCs) operating in batch mode was examined. Consecutive LSCVs at 0.1 mV s<jats:sup>−1</jats:sup> were recorded with and without prior renewal of the culture medium. Significant deviations in CV replicates were observed when the medium was not replaced (as high as 40% of maximum intensity). These deviations decreased (&lt;18%) when the medium was refreshed, indicating that significant changes in the culture medium composition occurred during LSCVs. Additional electrochemical tests showed that the peak in the forward scan was probably the result of an accumulation of charge in the anodic system.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>LSCV can affect the response of AC‐MFCs working in batch mode and cast doubt on the repeatability of these experiments, observing differences as high as 40% in maximum intensity. Renewing the culture medium is recommended to improve the repeatability of LSCV replicates. © 2020 Society of Chemical Industry</jats:p></jats:sec>

Wei-Jhe Ma, Ching-Hsing Luo, Jiun-Ling Lin et al.

Sensors • 0

<jats:p>This paper presents a portable low-power battery-driven bioelectrochemical signal acquisition system for urea detection. The proposed design has several advantages, including high performance, low cost, low-power consumption, and high portability. A LT1789-1 low-supply-voltage instrumentation amplifier (IA) was used to measure and amplify the open-circuit potential (OCP) between the working and reference electrodes. An MSP430 micro-controller was programmed to process and transduce the signals to the custom-developed software by ZigBee RF module in wireless mode and UART in able mode. The immobilized urease sensor was prepared by embedding urease into the polymer (aniline-co-o-phenylenediamine) polymeric matrix and then coating/depositing it onto a MEMS-fabricated Au working electrode. The linear correlation established between the urea concentration and the potentiometric change is in the urea concentrations range of 3.16 × 10−4 to 3.16 × 10−2 M with a sensitivity of 31.12 mV/log [M] and a precision of 0.995 (R2 = 0.995). This portable device not only detects urea concentrations, but can also operate continuously with a 3.7 V rechargeab-le lithium-ion battery (500 mA·h) for at least four days. Accordingly, its use is feasible and even promising for home-care applications.</jats:p>

Nattawet Sriwichai, Rutrawee Sangcharoen, Treenut Saithong et al.

PLOS ONE • 0

<jats:p>Microbial fuel cells (MFCs) are innovative eco-friendly technologies that advance a circular economy by enabling the conversion of both organic and inorganic substances in wastewater to electricity. While conceptually promising, there are lingering questions regarding the performance and stability of MFCs in real industrial settings. To address this research gap, we investigated the influence of specific operational settings, regarding the hydraulic retention time (HRT) and organic loading rate (OLR) on the performance of MFCs used for treating sulfide-rich wastewater from a canned pineapple factory. Experiments were performed at varying hydraulic retention times (2 days and 4 days) during both low and high seasonal production. Through optimization, we achieved a current density generation of 47±15 mA/m<jats:sup>2</jats:sup>, a COD removal efficiency of 91±9%, and a sulfide removal efficiency of 86±10%. Microbiome analysis revealed improved MFC performance when there was a substantial presence of electrogenic bacteria, sulfide-oxidizing bacteria, and methanotrophs, alongside a reduced abundance of sulfate-reducing bacteria and methanogens. In conclusion, we recommend the following operational guidelines for applying MFCs in industrial wastewater treatment: (i) Careful selection of the microbial inoculum, as this step significantly influences the composition of the MFC microbial community and its overall performance. (ii) Initiating MFC operation with an appropriate OLR is essential. This helps in establishing an effective and adaptable microbial community within the MFCs, which can be beneficial when facing variations in OLR due to seasonal production changes. (iii) Identifying and maintaining MFC-supporting microbes, including those identified in this study, should be a priority. Keeping these microbes as an integral part of the system’s microbial composition throughout the operation enhances and stabilizes MFC performance.</jats:p>

Zhe Liu, Ping Xiang, Zhuang Duan et al.

RSC Advances • 0

<p>A three-chamber microbial desalination cell (MDC) was constructed for high-salinity mustard tuber wastewater (MTWW) treatment.</p>

Da Seul Kong, Eun Joo Park, Sakuntala Mutyala et al.

Energies • 0

<jats:p>Crude glycerol is a major byproduct in the production of biodiesel and contains a large number of impurities. The transformation of crude glycerol into valuable compounds such as 1,3-propanediol (1,3-PDO) using clean and renewable processes, like bioconversion, is an important task for the future of the chemical industry. In this study, 1,3-PDO bioproductions from crude and pure glycerol were estimated as 15.4 ± 0.8 and 11.4 ± 0.1 mmol/L, respectively. Because 1,3-PDO is a reductive metabolite that requires additional reducing energy, external supplements of electron for further improvement of 1,3-PDO biosynthesis were attempted using a bioelectrochemical system (BES) or zero-valent iron (ZVI). The conversions of crude and pure glycerol under electrode and iron-based cultivation were investigated for 1,3-PDO production accompanied by metabolic shift and cell growth. The BES-based conversion produced 32.6 ± 0.6 mmol/L of 1,3-PDO with ZVI implementation.</jats:p>

Na Liu, Lina Qiu, Lijuan Qiu

Coatings • 0

<jats:p>Microbial metal corrosion has become an important topic in metal research, which is one of the main causes of equipment damage, energy loss, and economic loss. At present, the research on microbial metal corrosion focuses on the characteristics of corrosion products, the environmental conditions affecting corrosion, and the measures and means of corrosion prevention, etc. In contrast, the main microbial taxa involved in metal corrosion, their specific role in the corrosion process, and the electron transfer pathway research are relatively small. This paper summarizes the mechanism of microbial carbon steel corrosion caused by SRB, including the cathodic depolarization theory, acid metabolite corrosion theory, and the biocatalytic cathodic sulfate reduction mechanism. Based on the reversible nature of electron transfer in biofilms and the fact that electrons must pass through the extracellular polymers layer between the solid electrode and the cell, this paper focuses on three types of electrochemical mechanisms and electron transfer modes of extracellular electron transfer occurring in microbial fuel cells, including direct-contact electron transfer, electron transfer by conductive bacterial hair proteins or nanowires, and electron shuttling mediated by the use of soluble electron mediators. Finally, a more complete pathway of electron transfer in microbial carbon steel corrosion due to SRB is presented: an electron goes from the metal anode, through the extracellular polymer layer, the extracellular membrane, the periplasm, and the intracellular membrane, to reach the cytoplasm for sulfate allosteric reduction. This article also focuses on a variety of complex components in the extracellular polymer layer, such as extracellular DNA, quinoline humic acid, iron sulfide (FeSX), Fe3+, etc., which may act as an extracellular electron donor to provide electrons for the SRB intracellular electron transfer chain; the bioinduced mineralization that occurs in the SRB biofilm can inhibit metal corrosion, and it can be used for the development of green corrosion inhibitors. This provides theoretical guidance for the diagnosis, prediction, and prevention of microbial metal corrosion.</jats:p>

Thi Quynh Hoa Kieu, Thi Yen Nguyen, Chi Linh Do

Molecules • 0

<jats:p>A wastewater treatment system has been established based on sulfate-reducing and sulfide—oxidizing processes for treating organic wastewater containing high sulfate/sulfide. The influence of COD/SO42− ratio and hydraulic retention time (HRT) on removal efficiencies of sulfate, COD, sulfide and electricity generation was investigated. The continuous operation of the treatment system was carried out for 63 days with the optimum COD/SO42− ratio and HRT. The result showed that the COD and sulfate removal efficiencies were stable, reaching 94.8 ± 0.6 and 93.0 ± 1.3% during the operation. A power density level of 18.0 ± 1.6 mW/m2 was obtained with a sulfide removal efficiency of 93.0 ± 1.2%. However, the sulfide removal efficiency and power density decreased gradually after 45 days. The results from scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX) show that sulfur accumulated on the anode, which could explain the decline in sulfide oxidation and electricity generation. This study provides a promising treatment system to scale up for its actual applications in this type of wastewater.</jats:p>

V. Dhundale, Vijayshree M Hemke, D. Desai et al.

Annals of Applied Microbiology &amp; Biotechnology Journal • 2018

Microbial fuel cells (MFCs), which can be use bacterial cultures as biocatalyst for the conversion of chemical energy into the electricity from the biomass. The bacteria that can be able to synthesis [1,2] the electron from biodegradation of organic content and transfer the electron are known as exoelectrogen [3]. Now a days the extensive work is performed on the many exoelectrogen in MFCs which were Gram-negative and most exoelectrogens are cultivated in MFCs under 7 pH such as Klebsiella pneumoniae, Desulfobulbus propionicus, Geobacter sulfurreducens, Rhodoferax ferrireducens, Aeromonas hydrophila and Shewanella putrefaciens [4-9]. The extensive bacterial cultures that have been examined as biocatalyst for the bioelectricity generation in MFC comprise the pure culture of aerobic and anaerobic bacteria and consortial diverse cultures from sea floor sediments [10] and wastewater [11-12]. For direct bio electricity generation in MFC, the ideal bacterial culture must be able to grow aerobically and be electrochemically active, utilizing an anode as an alternative electron acceptor while oxidizing metabolites of various carbon sources. But very less studies have been reported using Gram-positive bacteria as biocatalyst in MFCs like Corynebacterium sp. strain MFC03 [13] Thermincola ferriacetica Z-0001 [14] and Bacillus subtilis [15], Clostridium butyricum EG3 [16], were performed to be enable producing bioelectricity. Electrochemical mechanisms have been used in different fields of biotechnology including biosensors, bioelectrochemical synthesis and biofuel cells [17]. Electricity can be generated directly from sewage sludge with microbial fuel cells (MFCs), combining degradation of organic matter and MFC for the generation of bioelectricity and the degradation of sewage sludgeorganic matter under the alkaline condition studied by Yuan et al. A group of bacteria from the extremophiles that has been tested only to a lower range in MFCs. Extremes such as in pH, salinity, temperature and alkalinity, when combined with materials that perform best under such circumstances would able to result in more graceful MFCs [18]. The search for bacteria that function optimally at higher pH and thereby would have higher catalytic rates was the aim of the present study. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes was studied by Miller and Oremland. The objectives of this Research Article

V. Dhundale, Vijayshree M Hemke, D. Desai et al.

Journal of Applied Biology &amp; Biotechnology • 2020

The present study put forth with the fundamental objective to the exploration of exoelectrogens from the extremophilic environment and to investigate the electricity generation from them. A total of 20 bacterial cultures were isolated, from which BW2(1) was selected for the further investigation of the microbial fuel cell (MFC). The experimental results performed that the strain Bacillus alkalogaya BW2(1) was capable of utilizing organic acids and sugars as electron donors to generate electricity. The MFC was constructed and the electricity generation was measured after various intervals using various parameters and substrates, 937 mV electricity was generated after 1 hour, but after 48 hours the electricity generation dramatically decreases to 570 mV. The effect of pH on MFC was also studied, pH enhanced electricity, indicating the requirement of pH for bacterium BW2(1). This is a valuable information for bioelectricity production and optimization from B. alkalogaya BW2(1) has bright future toward the improvement and production of bioelectricity for entirely new areas of industrial and biotechnological applications.

Xiaofei Wang, Antonin Prévoteau, K. Rabaey

Environmental Science &amp; Technology • 2021

Nitrate contamination is a common problem in groundwater around the world. Nitrate can be cathodically reduced in bioelectrochemical systems using autotrophic denitrifiers with low energy investment and without chemical addition. Successful denitrification was demonstrated in previous studies in both microbial fuel cells and microbial electrolysis cells (MECs) with continuous current flow, whereas the impact of intermittent current supply (e.g., in a fluidized-bed system) on denitrification and particularly the electron-storing capacity of the denitrifying electroactive biofilms (EABs) on the cathodes have not been studied in depth. In this study, two continuously fed MECs were operated in parallel under continuous and periodic polarization modes over 280 days, respectively. Under continuous polarization, the maximum denitrification rate reached 233 g NO3--N/m3/d with 98% nitrate removal (0.6 mg NO3--N/L in the effluent) with negligible intermediate production, while under a 30 s open-circuit/30 s polarization mode, 86% of nitrate was removed at a maximum rate of 205 g NO3--N/m3/d (4.5 mg NO3--N/L in the effluent) with higher N2O production (6.6-9.3 mg N/L in the effluent). Conversely, periodic polarization could be an interesting approach in other bioelectrochemical processes if the generation of chemical intermediates (partially reduced or oxidized) should be favored. Similar microbial communities dominated byGallionellaceaewere found in both MECs; however, swapping the polarization modes and the electrochemical analyses suggested that the periodically polarized EABs probably developed a higher ability for electron storage and transfer, which supported the direct electron transfer pathway in discontinuous operation or fluidized biocathodes.

Eleanor R. Clifford, R. Bradley, L. Wey et al.

Chemical Science • 2021

Bioelectrochemical approaches for energy conversion rely on efficient wiring of natural electron transport chains to electrodes. However, state-of-the-art exogenous electron mediators give rise to significant energy losses and, in the case of living systems, long-term cytotoxicity. Here, we explored new selection criteria for exogenous electron mediation by examining phenazines as novel low-midpoint potential molecules for wiring the photosynthetic electron transport chain of the cyanobacterium Synechocystis sp. PCC 6803 to electrodes. We identified pyocyanin (PYO) as an effective cell-permeable phenazine that can harvest electrons from highly reducing points of photosynthesis. PYO-mediated photocurrents were observed to be 4-fold higher than mediator-free systems with an energetic gain of 200 mV compared to the common high-midpoint potential mediator 2,6-dichloro-1,4-benzoquinone (DCBQ). The low-midpoint potential of PYO led to O2 reduction side-reactions, which competed significantly against photocurrent generation; the tuning of mediator concentration was important for outcompeting the side-reactions whilst avoiding acute cytotoxicity. DCBQ-mediated photocurrents were generally much higher but also decayed rapidly and were non-recoverable with fresh mediator addition. This suggests that the cells can acquire DCBQ-resistance over time. In contrast, PYO gave rise to steadier current enhancement despite the co-generation of undesirable reactive oxygen species, and PYO-exposed cells did not develop acquired resistance. Moreover, we demonstrated that the cyanobacteria can be genetically engineered to produce PYO endogenously to improve long-term prospects. Overall, this study established that energetic gains can be achieved via the use of low-potential phenazines in photosynthetic bioelectrochemical systems, and quantifies the factors and trade-offs that determine efficacious mediation in living bioelectrochemical systems.

Roman N. Perchikov, Maxim Cheliukanov, Yulia V. Plekhanova et al.

Biosensors • 2024

Microbial biofilms present one of the most widespread forms of life on Earth. The formation of microbial communities on various surfaces presents a major challenge in a variety of fields, including medicine, the food industry, shipping, etc. At the same time, this process can also be used for the benefit of humans—in bioremediation, wastewater treatment, and various biotechnological processes. The main direction of using electroactive microbial biofilms is their incorporation into the composition of biosensor and biofuel cells This review examines the fundamental knowledge acquired about the structure and formation of biofilms, the properties they have when used in bioelectrochemical devices, and the characteristics of the formation of these structures on different surfaces. Special attention is given to the potential of applying the latest advances in genetic engineering in order to improve the performance of microbial biofilm-based devices and to regulate the processes that take place within them. Finally, we highlight possible ways of dealing with the drawbacks of using biofilms in the creation of highly efficient biosensors and biofuel cells.

O. Kalashnikova, A. Kashevskii, N. Vardanyan et al.

Proceedings of Universities. Applied Chemistry and Biotechnology • 2021

Acidophilic chemolithotrophic microorganisms are used in biohydrometallurgy for the extraction of metals from sulphide ores. Some types of microorganisms belonging to this group are capable of generating electricity under certain conditions. This circumstance determined a recent upsurge of research interest in their use in biofuel cells. Under a constant supply of the substrate to the bioelectrochemical system, acidophilic chemolithotrophic microorganisms are capable of producing electricity for a prolonged period of time. The use of extremophiles in microbial fuel cells is of particular interest, since these microorganisms can serve as bioelectrocatalysts at extreme pH, salinity and temperature, while the vast majority of microorganisms are unable to survive under these conditions. Therefore, selection of optimal conditions and approaches to controlling the work of acidophilic chemolithotrophic microorganisms in such fuel cells is of particular importance. On this basis, a technology for the simulteneous bioleaching of metals from poor ores and the generation of electricity can be developed. Biofuel cells operating at low pH values using acidophilic chemolithotrophic microorganisms are yet to be investigated. The number of studies on acidophilic electroactive microorganisms is very limited. In this regard, the purpose of this review was to consider the prospects for the use of acidophilic chemolithotrophic microorganisms as bioagents in microbial fuel cells. The reviewed publications demonstrate that chemolithotrophic microorganisms can act as both anodic (metal-reducing, sulphur-oxidizing microorganisms) and cathodic (metal-oxidizing prokaryotes, sulfate reducers) highly efficient bioagents capable of using mining wastes as substrates.

Yuxuan Wan, Zongliang Huang, Lean Zhou et al.

Environmental Science &amp; Technology • 2019

Nitrate-N in wastewaters is hard to be recovered because it is difficult to volatilize with an opposite charge to ammonium. Here, we proved the feasibility of dissimilatory nitrate reduction to ammonia (DNRA) by the easy-acclimated mixed electroactive bacteria, achieving the highest DNRA efficiency of 44 %. It was then coupled with microbial electrolysis to concentrate the ammonium by a factor of 4 in the catholyte for recovery. The abundance of electroactive bacteria in the biofilm before nitrate addition, especially Geobacter spp., was found to determine the DNRA efficiency. As the main competitors of DNRA bacteria, the growth of denitrifiers was more sensitive to C/N ratios. DNRA microbial community contrarily showed a stable and recoverable ammoniation performance over C/N ratios ranging from 0.5 to 8.0. A strong competition of electrode and nitrate on electron donors was observed at the early stage (15 d) of electroactive biofilm formation, which can be weakened when the biofilm was mature on 40 d. Quantitative PCR showed a significant increase in nirS and nrfA transcripts in ammoniation process. nirS was inhibited significantly after nitrate depletion while nrfA was still up-regulated. These findings provided a novel way to recover nitrate-N using the organic wastes as both electron donor and power, which has broader implications on the sustainable wastewater treatment and the ecology of nitrogen cycling.

Chuanqi Liu, Xin Yuan, Yuyi Gu et al.

ACS Sustainable Chemistry &amp; Engineering • 2020

Bioelectrochemical CO2 reduction is a promising method for biogas upgrading. However, the CO2 reduction efficiency in these bioelectrical systems is always relatively low and limits their applicati...

C. Santoro, María José Salar García, X. A. Walter et al.

ChemElectroChem • 2020

Abstract In recent years, human urine has been successfully used as an electrolyte and organic substrate in bioelectrochemical systems (BESs) mainly due of its unique properties. Urine contains organic compounds that can be utilised as a fuel for energy recovery in microbial fuel cells (MFCs) and it has high nutrient concentrations including nitrogen and phosphorous that can be concentrated and recovered in microbial electrosynthesis cells and microbial concentration cells. Moreover, human urine has high solution conductivity, which reduces the ohmic losses of these systems, improving BES output. This review describes the most recent advances in BESs utilising urine. Properties of neat human urine used in state‐of‐the‐art MFCs are described from basic to pilot‐scale and real implementation. Utilisation of urine in other bioelectrochemical systems for nutrient recovery is also discussed including proofs of concept to scale up systems.

Reham A Alfadaly, A. Elsayed, Rabeay Y. A. Hassan et al.

Molecules • 2021

The presence of inorganic pollutants such as Cadmium(II) and Chromium(VI) could destroy our environment and ecosystem. To overcome this problem, much attention was directed to microbial technology, whereas some microorganisms could resist the toxic effects and decrease pollutants concentration while the microbial viability is sustained. Therefore, we built up a complementary strategy to study the biofilm formation of isolated strains under the stress of heavy metals. As target resistive organisms, Rhizobium-MAP7 and Rhodotorula ALT72 were identified. However, Pontoea agglumerans strains were exploited as the susceptible organism to the heavy metal exposure. Among the methods of sensing and analysis, bioelectrochemical measurements showed the most effective tools to study the susceptibility and resistivity to the heavy metals. The tested Rhizobium strain showed higher ability of removal of heavy metals and more resistive to metals ions since its cell viability was not strongly inhibited by the toxic metal ions over various concentrations. On the other hand, electrochemically active biofilm exhibited higher bioelectrochemical signals in presence of heavy metals ions. So by using the two strains, especially Rhizobium-MAP7, the detection and removal of heavy metals Cr(VI) and Cd(II) is highly supported and recommended.

Sirine Saadaoui, B. Erable, Nesrine Saidi et al.

Applied Sciences • 2023

The treatment of textile wastewater (TWW) loaded with recalcitrant azo dyes in bioelectrochemical systems (BES) rather than in physicochemical processes is a low-cost and environmentally friendly process. The main objective of this study is to investigate the potential of different saline sediments collected from extreme Tunisian environments for the formation of bioanodes capable ofsimultaneous azo dyes degradation and electric current generation in synthetic (STWW) and real textile wastewaters (RTWW) characterized by a varied composition of azo dyes and a high salinity. The obtained bioanodes and anolytes were studied comparatively by electrochemical, microscopic, analytical, and molecular tools.Based on the UV–visible spectra analysis, the breakdown of the azo bond was confirmed. With RTWW, the BES achieved a chemical oxygen demand (COD) abatement rate of 85%with a current density of 2.5 A/m2. Microbial community analysis indicated that a diverse community of bacteria was active for effluent treatment coupled with energy production. At the phylum level, the electrodes were primarily colonized by proteobacteria and firmicutes, which are the two phyla most involved in bioremediation. The analysis of the microbial community also showed the abundance of Marinobacter hydrocarbonoclasticus and Marinobacter sp. species characterized by their high metabolic capacity, tolerance to extremophilic conditions, and role in hydrocarbon degradation.

H. Pham, Phuong Ha Vu, Thuy T. M. Nguyen et al.

Journal of Microbiology and Biotechnology • 2019

Sediment bioelectrochemical systems (SBESs) can be integrated into brackish aquaculture ponds for in-situ bioremediation of the pond water and sediment. Such an in-situ system offers advantages including reduced treatment cost, reusability and simple handling. In order to realize such an application potential of the SBES, in this laboratory-scale study we investigated the effect of several controllable and uncontrollable operational factors on the in-situ bioremediation performance of a tank model of a brackish aquaculture pond, into which a SBES was integrated, in comparison with a natural degradation control model. The performance was evaluated in terms of electricity generation by the SBES, COD removal and nitrogen removal of both the tank water and the tank sediment. Real-life conditions of the operational parameters were also experimented to understand the most close-to-practice responses of the system to their changes. Predictable effects of controllable parameters including external resistance and electrode spacing, similar to those reported previously for the BESs, were shown by the results but exceptions were observed. Accordingly, while increasing the electrode spacing reduced the current densities but generally improved COD and nitrogen removal, increasing the external resistance could result in decreased COD removal but also increased nitrogen removal and decreased current densities. However, maximum electricity generation and COD removal efficiency difference of the SBES (versus the control) could be reached with an external resistance of 100 Ω, not with the lowest one of 10 Ω. The effects of uncontrollable parameters such as ambient temperature, salinity and pH of the pond (tank) water were rather unpredictable. Temperatures higher than 35 °C seemed to have more accelaration effect on natural degradation than on bioelectrochemical processes. Changing salinity seriously changed the electricity generation but did not clearly affect the bioremediation performance of the SBES, although at 2.5% salinity the SBES displayed a significantly more efficient removal of nitrogen in the water, compared to the control. Variation of pH to practically extreme levels (5.5 and 8.8) led to increased electricity generations but poorer performances of the SBES (vs. the control) in removing COD and nitrogen. Altogether, the results suggest some distinct responses of the SBES under brackish conditions and imply that COD removal and nitrogen removal in the system are not completely linked to bioelectrochemical processes but electrochemically enriched bacteria can still perform non-bioelectrochemical COD and nitrogen removals more efficiently than natural ones. The results confirm the application potential of the SBES in brackish aquaculture bioremediation and help propose efficient practices to warrant the success of such application in real-life scenarios.

H. Pham, Hien Tran, Linh Vu et al.

Journal of Microbiology and Biotechnology • 2019

In this study, we investigated the potential of using sediment bioelectrochemical systems (SBESs) for in-situ treatment of the water and the sediment of brackish aquaculture ponds polluted with uneaten feed. A SBES integrated into a laboratory-scale tank simulating a brackish aquaculture pond was established. Such a tank (test tank) and the control (not containing the SBES) were fed with shrimp feed in a scheme that mimics a situation where 50% of feed is uneaten. After the SBES was inoculated with microbial sources from actual shrimp pond sediments, electricity generation was well observed from the first experimental week, indicating a successful enrichment of electrochemically active bacteria at the sediment of the test tank. The electricity generation became steady after 3 weeks of operation, with an average current density of 2.3 mA m-2 anode surface and an average power density of 0.05 mW m-2 anode surface. At the steady state, the SBES removed 20-30% more COD of the tank water, compared to the control. After 1 year, the SBES also reduced the amount of the sediment in the tank by 40% and thus could remove approximately 40% more COD and approximately 52% more nitrogen of the sediment, compared to the control. Insignificant amount of nitrite and nitrate was detected, suggesting a complete removal of nitrogen by the system. PCR-DGGE-based analyses revealed the dominant presence of Methylophilus rhizosphaerae, Desulfatitalea tepidiphila and Thiothrix eikelboomii, which have not been found in bioelectrochemical systems before, in the bacterial community in the sediment of the SBES-containing tank. This community was significantly distinct from those of the inoculum and the control tank, which were more related to each other. The results of this research demonstrate the potential application of SBESs for in-situ water and sediment reclamation of brackish aquaculture systems, which will certainly help reduce water pollution threats, fish and shrimp disease risks and thus farmers' losses.

Paolo Dessì, Estefania Porca, Johanna Haavisto et al.

RSC Advances • 0

<p>A mesophilic (37 °C) and a thermophilic (55 °C) two-chamber microbial fuel cell (MFC) were studied and compared for their power production from xylose and the anode-attached, membrane-attached and planktonic microbial communities involved.</p>

Míriam Cerrillo, Victor Riau, August Bonmatí

Membranes • 0

<jats:p>Bioelectrochemical systems (BESs) have emerged as a technology that is able to recover resources from different kinds of substrates, especially wastewater. Nutrient recovery, mostly based on membrane reactor configuration, is a clear niche for BES application. The recovery of nitrogen or phosphorus allows for treatment of wastewater while simultaneously collecting a concentrated stream with nutrients that can be reintroduced into the system, becoming a circular economy solution. The aim of this study is to review recent advances in membrane-based BESs for nitrogen and phosphorus recovery and compare the recovery efficiencies and energy requirements of each system. Finally, there is a discussion of the main issues that arise from using membrane-based BESs. The results presented in this review show that it would be beneficial to intensify research on BESs to improve recovery efficiencies at the lowest construction cost in order to take the final step towards scaling up and commercialising this technology.</jats:p>

Angel Franco, Mahmoud Elbahnasy, Miriam A. Rosenbaum

Microbial Biotechnology • 2023

<jats:title>Abstract</jats:title><jats:p>Mediated extracellular electron transfer (EET) might be a great vehicle to connect microbial bioprocesses with electrochemical control in stirred‐tank bioreactors. However, mediated electron transfer to date is not only much less efficient but also much less studied than microbial direct electron transfer to an anode. For example, despite the widespread capacity of pseudomonads to produce phenazine natural products, only <jats:italic>Pseudomonas aeruginosa</jats:italic> has been studied for its use of phenazines in bioelectrochemical applications. To provide a deeper understanding of the ecological potential for the bioelectrochemical exploitation of phenazines, we here investigated the potential electroactivity of over 100 putative diverse native phenazine producers and the performance within bioelectrochemical systems. Five species from the genera <jats:italic>Pseudomonas</jats:italic>, <jats:italic>Streptomyces</jats:italic>, <jats:italic>Nocardiopsis</jats:italic>, <jats:italic>Brevibacterium</jats:italic> and <jats:italic>Burkholderia</jats:italic> were identified as new electroactive bacteria. Electron discharge to the anode and electric current production correlated with the phenazine synthesis of <jats:italic>Pseudomonas chlororaphis</jats:italic> subsp. <jats:italic>aurantiaca</jats:italic>. Phenazine‐1‐carboxylic acid was the dominant molecule with a concentration of 86.1 μg/ml mediating an anodic current of 15.1 μA/cm<jats:sup>2</jats:sup>. On the other hand, <jats:italic>Nocardiopsis chromatogenes</jats:italic> used a wider range of phenazines at low concentrations and likely yet‐unknown redox compounds to mediate EET, achieving an anodic current of 9.5 μA/cm<jats:sup>2</jats:sup>. Elucidating the energetic and metabolic usage of phenazines in these and other species might contribute to improving electron discharge and respiration. In the long run, this may enhance oxygen‐limited bioproduction of value‐added compounds based on mediated EET mechanisms.</jats:p>

Edoardo Dell’Armi, Marco Zeppilli, Bruna Matturro et al.

Processes • 0

<jats:p>Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants due to their improper use in several industrial activities. Specialized microorganisms are able to perform the reductive dechlorination (RD) of high-chlorinated CAHs such as perchloroethylene (PCE), while the low-chlorinated ethenes such as vinyl chloride (VC) are more susceptible to oxidative mechanisms performed by aerobic dechlorinating microorganisms. Bioelectrochemical systems can be used as an effective strategy for the stimulation of both anaerobic and aerobic microbial dechlorination, i.e., a biocathode can be used as an electron donor to perform the RD, while a bioanode can provide the oxygen necessary for the aerobic dechlorination reaction. In this study, a sequential bioelectrochemical process constituted by two membrane-less microbial electrolysis cells connected in series has been, for the first time, operated with synthetic groundwater, also containing sulphate and nitrate, to simulate more realistic process conditions due to the possible establishment of competitive processes for the reducing power, with respect to previous research made with a PCE-contaminated mineral medium (with neither sulphate nor nitrate). The shift from mineral medium to synthetic groundwater showed the establishment of sulphate and nitrate reduction and caused the temporary decrease of the PCE removal efficiency from 100% to 85%. The analysis of the RD biomarkers (i.e., Dehalococcoides mccartyi 16S rRNA and tceA, bvcA, vcrA genes) confirmed the decrement of reductive dechlorination performances after the introduction of the synthetic groundwater, also characterized by a lower ionic strength and nutrients content. On the other hand, the system self-adapted the flowing current to the increased demand for the sulphate and nitrate reduction, so that reducing power was not in defect for the RD, although RD coulombic efficiency was less.</jats:p>

Matteo Grattieri, Kamrul Hasan, Shelley D. Minteer

ChemElectroChem • 2017

<jats:title>Abstract</jats:title><jats:p>Microbial bioelectrocatalysis, the process of utilizing an intact microorganism for catalyzing redox reactions, has been rapidly expanding over the last 15 years. Although microbial bioelectrocatalysis has been primarily studied for power generation and wastewater treatment, this Minireview will focus on the use of bioelectrochemical systems (BESs) for biosensing applications. This will include sensors for water quality, corrosion, and toxic shock. We will also discuss the transition of BESs to photo‐BESs and discuss their recent applications in sensing. Finally, we will discuss the future outlook for microbial bioelectrocatalysis for biosensing applications.</jats:p>

Asiah Sukri, Raihan Othman, Firdaus Abd-Wahab et al.

Energies • 0

<jats:p>The present work describes a self-sustaining bioelectrochemical system that adopts simple cell configurations and operates in uncontrolled ambient surroundings. The microbial fuel cell (MFC) was comprised of white-rot fungus of Phanaerochaete chrysosporium fed with oil palm empty fruit bunch (EFB) as the substrate. This fungal strain degrades lignin by producing ligninolytic enzymes such as laccase, which demonstrates a specific affinity for oxygen as its electron acceptor. By simply pairing zinc and the air electrode in a membraneless, single-chamber, 250-mL enclosure, electricity could be harvested. The microbial zinc/air cell is capable of sustaining a 1 mA discharge current continuously for 44 days (i.e., discharge capacity of 1056 mAh). The role of the metabolic activities of P. chrysosporium on EFB towards the MFC’s performance is supported by linear sweep voltammetry measurement and scanning electron microscopy observations. The ability of the MFC to sustain its discharge for a prolonged duration despite the fungal microbes not being attached to the air electrode is attributed to the formation of a network of filamentous hyphae under the submerged culture. Further, gradual lignin decomposition by fungal inocula ensures a continuous supply of laccase enzyme and radical oxidants to the MFC. These factors promote a self-sustaining MFC devoid of any control features.</jats:p>