Electricity generation and microbial community in long-running microbial fuel cell for high-salinity mustard tuber wastewater treatment

Electricity production and nutrient recovery from waste activated sludge via microbial fuel cell and subsequent struvite crystallization: Effect of low temperature thermo-alkaline pretreatment

Microbial fuel cell (MFC) and subsequent struvite crystallization are available low-carbon environmental- friendly techniques for resource utilization of waste activated sludge (WAS). In this study, low temperature thermo-alkaline pretreatment (LTTAP) was innovatively proposed for enhancing MFC electricity generation and subsequent struvite crystallization from WAS. The results indicated that LTTAP at 75 °C and pH 10 not only substantially shortened the start-up time of MFC to 3-4 days, but also significantly increased maximum power density to 5.38 W/m3. Moreover, thermo-alkaline pretreated WAS effectively exhibited stable and high output voltage over long period, compared to unpretreated WAS. Furthermore, pretreated WAS can provide an effective pH buffering function for MFC operation. In addition, about 90 % of phosphate in the pretreated WAS supernatant was recovered by struvite crystallization. The findings herein provided a new route for enhancing electricity production and nutrient recovery from WAS, which can realize the full-scale applicationof WAS resource utilization.

Synergistic enhancement of microbes-to-pollutants and inter-microbes electron transfer by Fe, N modified ordered mesoporous biochar in anaerobic digestion

Extracellular electron transfer was essential for degrading recalcitrant pollutants by anaerobic digestion (AD). Therefore, existing studies improved AD efficiency by enhancing the electron transfer from microbes-to-pollutants or inter-microbes. This study synthesized a novel Fe, N co-doped biochar (Fe, N-BC), which could enhance both the microbes-to-pollutants and inter-microbes electron transfer in AD. Detailed characterization data indicated that Fe, N-BC has an ordered mesoporous structure, high specific surface area (463.46 m2/g), and abundant redox functional groups (Fe2+/Fe3+, pyrrolic-N), which translate into excellent biocompatibility and electrochemical properties of Fe, N-BC. By adding Fe, N-BC, the stability and efficiency of the medium-temperature AD system in the treatment of methyl orange (MO) wastewater were improved: obtained a high degradation efficiency of MO (96.8 %) and enhanced the methane (CH4) production by 65 % compared to the control group. Meanwhile, Fe, N-BC reduced the accumulation of volatile fatty acids in the AD system, and the activity of anaerobic granular sludge electron transport system and coenzyme F420 was enhanced. In addition, Fe, N-BC showed positive enrichment of azo dyes decolorization bacteria (Georgenia) and direct interspecies electron transfer (DIET) synergistic partners (Syntrophobacter, Methanosarcina). Overall, the rapid degradation of MO and enhanced CH4 production in AD systems by Fe, N-BC is associated with enhancing two electronic pathways, i.e., microbes to MO and DIET between syntrophic bacteria and methanogenic archaea. This study introduced an enhanced "two-pathways of electron transfer" theory, realized by Fe, N-BC. These findings provided new insights into the interactions within AD systems and offer strategies for enhancing their performance with recalcitrant pollutants.

Aerobic electrotrophic denitrification coupled with biologically induced phosphate precipitation for nitrogen and phosphorus removal from high-salinity wastewater: Performance, mechanism, and microbial community

Electrotrophic denitrification (ED) is a promising nitrogen removal technique; however, the potential of ED coupled with biologically induced phosphate precipitation (BIPP) has not been fully explored. In this study, the performances, mechanisms, and microbial communities of the coupled system were investigated. The results showed that excellent nitrogen and phosphorus removal (both exceeding 92 %) was achieved in the salinity range of 20-60 g/L. ED contributed to approximately 83.4 % of nitrogen removal. BIPP removed approximately 63.5 % of the phosphorus. Batch activity tests confirmed that aerobic/anoxic bio-electrochemical and autotrophic/heterotrophic denitrification worked together for nitrate removal. Sulfate reduction had a negative impact on denitrification. Moreover, phosphorus removal was controlled by ED and calcium ions. The alkaline solution environment created by denitrification may greatly promote the formation of hydroxyapatite. Microbial community analyses indicated that the key bacteria involved in aerobic ED was Arcobacter. These findings will aid in the advanced treatment of high-salinity wastewater.

Reduced formation of biogenic amines in low-salt Zhacai via fermentation under CO2-modified atmosphere

Reducing sodium salt content in traditional fermented vegetables and developing low-salt fermented products have attracted increasing attention.However, low-salt fermented vegetables are prone to accumulate toxic biogenic amines (BAs) caused by the undesirable metabolism of spoilage microorganisms. This study aimed to investigate the impact of a CO₂-modified atmosphere (MA) approach to the fermentation of low-salt Zhacai and the accumulation of BAs. The results show CO₂-MA effectively suppressed the production of excessive BAs in low-salt Zhacai, as evidenced by a decrease in the total BA content from 63.66 to 161.41 mg/ kg under natural air conditions to 1.88-24.76 mg/ kg under CO₂-MA. Overall, the mechanism of hindering BA formation was closely related to the change in the microbial community and the downregulation of BA-producing enzymes. Lactic acid bacteria, including Lactiplantibacillus plantarum, Weissella spp., and Pediococcus spp., were enriched under CO₂-MA, whereas amine-producing microorganisms (e.g., Halomonas spp., Psychrobacter spp., Corynebacterium spp., and Levilactobacillus brevis) were greatly inhibited. Moreover, metagenomic analysis revealed that genes encoding amino acid decarboxylase, amine deiminase, and amine synthase were downregulated, which could be the fundamental reason for BA reduction. This study provides an alternative method for reducing BA production in fermented food.

Recent progress in microbial fuel cells using substrates from diverse sources

Increasing untreated environmental outputs from industry and the rising human population have increased the burden of wastewater and other waste streams on the environment. The most prevalent wastewater treatment methods include the activated sludge process, which requires aeration and is, therefore, energy and cost-intensive. The current trend towards a circular economy facilitates the recovery of waste materials as a resource. Along with the amount, the complexity of wastewater is increasing day by day. Therefore, wastewater treatment processes must be transformed into cost-effective and sustainable methods. Microbial fuel cells (MFCs) use electroactive microbes to extract chemical energy from waste organic molecules to generate electricity via waste treatment. This review focuses use of MFCs as an energy converter using wastewater from various sources. The different substrate sources that are evaluated include industrial, agricultural, domestic, and pharmaceutical types. The article also highlights the effect of operational parameters such as organic load, pH, current, and concentration on the MFC output. The article also covers MFC functioning with respect to the substrate, and the associated performance parameters, such as power generation and wastewater treatment matrices, are given. The review also illustrates the success stories of various MFC configurations. We emphasize the significant measures required to fill in the gaps related to the effect of substrate type on different MFC configurations, identification of microbes for use as biocatalysts, and development of biocathodes for the further improvement of the system. Finally, we shortlisted the best performing substrates based on the maximum current and power, Coulombic efficiency, and chemical oxygen demand removal upon the treatment of substrates in MFCs. This information will guide industries that wish to use MFC technology to treat generated effluent from various processes.

Evidence and Mechanisms of Selenate Reduction to Extracellular Elemental Selenium Nanoparticles on the Biocathode

Intracellular selenium nanoparticles (SeNPs) production is a roadblock to the recovery of selenium from biological water treatment processes because it is energy intensive to break microbial cells and then separate SeNPs. This study provided evidence of significantly more extracellular SeNP production on the biocathode (97-99%) compared to the conventional reactors (1-90%) using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. The cathodic microbial community analysis showed that relative abundance of Azospira oryzae, Desulfovibrio, Stenotrophomonas, and Rhodocyclaceae was <1% in the inoculum but enriched to 10-21% for each group when the bioelectrochemical reactor reached a steady state. These four groups of microorganisms simultaneously produce intracellular and extracellular SeNPs in conventional biofilm reactors per literature review but prefer to produce extracellular SeNPs on the cathode. This observation may be explained by the cellular energetics: by producing extracellular SeNPs on the biocathode, microbes do not need to transfer selenate and the electrons from the cathode into the cells, thereby saving energy. Extracellular SeNP production on the biocathode is feasible since we found high concentrations of C-type cytochrome, which is well known for its ability to transfer electrons from electrodes to microbial cells and reduce selenate to SeNPs on the cell membrane.

Response of denitrifying anaerobic methane oxidation enrichment to salinity stress: Process and microbiology

Denitrifying anaerobic methane oxidation (DAMO) is a novel biological process which could decrease nitrogen pollution and methane emission simultaneously in wastewater treatment. Salinity as a key environmental factor has important effects on microbial community and activity, however, it remains unclear for DAMO microorganisms. In this study, response of the enrichment of DAMO archaea and bacteria to different salinity was investigated from the aspect of process and microbiology. The results showed that the increasing salinity from 0.14% to 25% evidently deteriorated DAMO process, with the average removal rate of nitrate and methane decreased from 1.91 mg N/(L·d) to 0.07 mg N/(L·d) and 3.22 μmol/d to 0.59 μmol/d, respectively. The observed IC₅₀ value of salinity on the DAMO culture was 1.73%. Further microbial analyses at the gene level suggested that the relative abundance of DAMO archaea in the enrichment decreased to 46%, 39%, 38% and 33% of the initial value. However, DAMO bacteria suffered less impact with the relative abundance maintaining over 75% of the initial value (except 1% salinity). In functional genes of DAMO bacteria, pmoA, decreased gradually from 100% to 86%, 43%, 15% and 2%, while mcrA (DAMO archaea) maintained at 67%-97%. This difference probably indicated DAMO bacteria appeared functional inhibition prior to community inhibition, which was opposite for the DAMO archaea. Results above-mentioned concluded that, though the process of nitrate-dependent anaerobic methane oxidation was driven by the couple of DAMO archaea and bacteria, they individually featured different response to high salinity stress. These findings could be helpful for the application of DAMO-based process in high salinity wastewater treatment, and also the understanding to DAMO microorganisms.

Hypersaline Wastewater Produced from Pickled Mustard Tuber (Chinese Zhacai): Current Treatment Status and Prospects

Pickled mustard tuber, a worldwide condiment, is increasing at a fast growth rate. Its production generates a considerable amount of hypersaline wastewater containing NaCl of 7 wt.%, COD of 30,000 mg L−1, NH3-N of 400 mg L−1, and TP of 300 mg L−1. Pickled mustard tuber wastewater (PMTW) has severe effects on crops, deterioration of water quality, soil infertility and ecological systems. Due to the technic difficulties and insufficient support from the local governments; however, PMTW has not yet been widely investigated and well summarized. Therefore, this manuscript reviewed the relatively latest advances in PMTW. Physicochemical and biological hybrid processes mainly treat PMTW and the corresponding cost is 6.00 US dollars per ton. In the context of double carbon capture capacity in China and the development of the pickled mustard industry, PMTW sauce and sustainable reuse such as nutrient recovery, acid and alkaline regeneration and renewable energy may be bright prospects.

Storage strategy for shale gas flowback water based on non-bactericide microorganism control

Shale gas is a promising unconventional natural gas in the world, however the produced flowback water have severe challenges to surrounding water resource. Conventional reuse technology uses bactericide to control corrosive microorganism, which might bring uncontrolled drug resistance and other secondary pollution. In this study, storage strategy of flowback water was designed as a pre-control stage to decline corrosive microorganism. Dissolved oxygen and temperature were chosen as two key parameters based on microbial physiological and biochemical characteristics. Results showed that under the cross effect of temperature and dissolved oxygen, 15 °C and anaerobic condition had the optimal microorganism control effectiveness. Microorganism amount and live/dead cell ratio decreased by 63.7% and 68.74% respectively compared raw water. COD removal efficiency reduced to only 20%, indicating that the microorganism activity was extremely inhibited. However, microorganism in flowback water was more sensitive to dissolved oxygen compared to temperature. Redundancy analysis confirmed that dissolved oxygen contribution was as high as 91.5% while temperature was not significant (p > 0.05), the contribution rate was only 8.5%. Thermococcus, Archaeoglobus, Thermovirga, Thermotoga and Moorella were the dominated thermophilic, anaerobic and sulfate reduction or metal corrosion microorganism in flowback water, so all these identified microorganisms were control targets. Importantly, all the target microorganisms detected in flowback water were declined after different storage strategies. This study provides an effective storage strategy for flowback water to inhibit the microbial amount and activity without biocides addition, which could help promote the green exploitation of shale gas.

Microbial fuel cells and their electrified biofilms

Bioelectrochemical systems (BES) represent a wide range of different biofilm-based bioreactors that includes microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial desalination cells (MDCs). The first described bioelectrical bioreactor is the Microbial Fuel Cell and with the exception of MDCs, it is the only type of BES that actually produces harvestable amounts of electricity, rather than requiring an electrical input to function. For these reasons, this review article, with previously unpublished supporting data, focusses primarily on MFCs. Of relevance is the architecture of these bioreactors, the type of membrane they employ (if any) for separating the chambers along with the size, as well as the geometry and material composition of the electrodes which support biofilms. Finally, the structure, properties and growth rate of the microbial biofilms colonising anodic electrodes, are of critical importance for rendering these devices, functional living 'engines' for a wide range of applications.

Selection Guidelines for Wind Energy Technologies

The building block of all economies across the world is subject to the medium in which energy is harnessed. Renewable energy is currently one of the recommended substitutes for fossil fuels due to its environmentally friendly nature. Wind energy, which is considered as one of the promising renewable energy forms, has gained lots of attention in the last few decades due to its sustainability as well as viability. This review presents a detailed investigation into this technology as well as factors impeding its commercialization. General selection guidelines for the available wind turbine technologies are presented. Prospects of various components associated with wind energy conversion systems are thoroughly discussed with their limitations equally captured in this report. The need for further optimization techniques in terms of design and materials used for the development of each component is highlighted.

Valorisation and emerging perspective of biomass based waste-to-energy technologies and their socio-environmental impact: A review

The economic developments around the globe resulted in the increased demand of energy, which overburdened the supply chain sources of energy. Fossil fuel reserves are exploited to meet the high demand of energy and their combustion is becoming the main source of environmental pollution. So there is dire need to find safe, renewable and sustainable energy resources. Waste to energy (WtE) may be viewed as a possible alternate source of energy, which is economically and environmentally sustainable. Municipal solid waste (MSW) is a major contributor to the development of renewable energy and sustainable environment. At present the scarcity of renewable energy resources and disposal of MSW is a challenging problem for the developing countries, which has generated a wide ranging socioeconomic and environmental problems. This situation stimulates the researchers to develop alternatives for converting WtE under a variety of scenarios. Herein, the present scenario in developing the WtE technologies such as, thermal conversion methods (Incineration, Gasification, Pyrolysis, Torrefaction), Plasma technology, Biochemical methods, Chemical and Mechanical methods, Bio-electrochemical process, Mechanical biological treatment (MBT), Photo-biological processes for efficacious energy recovery and the challenges confronted by developing and developed countries. In this review, a framework for the evaluation of WtE technologies has been presented for the ease of researchers working in the field. Furthermore, this review concluded that WtE is a potential renewable energy source that will partially satisfy the demand for energy and ensure an efficient MSW management to overcome the environmental pollution.

Substrate salinity: A critical factor regulating the performance of microbial fuel cells, a review

Substrate salinity is a critical factor influencing microbial fuel cells (MFCs) performance and various studies have suggested that increasing substrate salinity first improves MFC performance. However, a further increase in salinity that exceeds the salinity tolerance of exoelectrogens shows negative effects because of inhibited bacterial activity and increased activation losses. In this review, electricity generation and contaminant removal from saline substrates using MFCs are summarized, and results show different optimal salinities for obtaining maximum performance. Then, electroactive bacteria capable of tolerating saline environments and strategies for improving salinity tolerance are discussed. In addition to ohmic resistance and bacterial activity, membrane resistance and catalyst performance will also be affected by substrate salinity, all of which jointly contribute the final overall MFC performance. Therefore, the combined effect of salinity is analyzed to illustrate how the MFC performance changes with increasing salinity. Finally, the challenges and perspectives of MFCs operated in saline environments are discussed.

Long-term stable and energy-neutral mixed biofilm electrode for complete nitrogen removal from high-salinity wastewater: Mechanism and microbial community

The steady mixed biofilm electrode (MBE) was investigated for the removal of nitrogen from mustard tuber wastewater. Results showed that complete nitrogen removal occurred over a wide initial chemical oxygen demand (COD)/total nitrogen (TN) ratio ranging from 2.8 to 9.8 using MBE. MBE revealed broad-spectrum applicability for the treatment of high-salinity wastewater containing different forms of nitrogen. Bio-electrochemical process, in-situ heterotrophic nitrogen reduction, ammonia stripping, nitrogen assimilation, and endogenous denitrification coexisted for the removal of nitrogen. Batch activity tests and functional microorganism analysis confirmed that autotrophic/heterotrophic nitrification, anoxic/aerobic denitrification, and nitrogen bio-electrochemical reduction cooperated to achieve efficient nitrogen conversion. More importantly, the analysis of the preliminary energy balance demonstrated that MBE was self-sustaining. The long-term operation stability of MBE was of great importance for its practical application. The results provided herein offer new insights into bioelectrochemical nitrogen removal and resource treatment of high-salinity wastewater.

Dynamic evolution of electrochemical and biological features in microbial fuel cells upon chronic exposure to increasing oxytetracycline dosage

Dynamic changes in power generation and electrochemical properties were compared between the control microbial fuel cells (C-MFC) and an oxytetracycline (OTC)-treated MFC (O-MFC) on days 84, 139, 174, 224, 295, 307 and 353. The results showed that a high concentration of OTC (>5 mg·L^-1) could inhibit microbial activity and result in a decline of voltage output and power density compared with the same C-MFC. However, with the prolongation of incubation time, the inhibitory effect was gradually weakened. Electrochemical analyses demonstrated that long-term OTC acclimation reduced the ohmic and polarisation resistance of the anode, which was conducive to the recovery of electrochemical performance. More than 99% of 10 mg·L^-1 OTC could be removed within 48 h, and the antibacterial activity of the MFC effluent on Escherichia coli DH5α was conclusively eliminated. High-throughput sequencing analysis revealed that the diversity and richness of the microbial community decreased significantly after long-term OTC enrichment. Acinetobacter, Petrimonas, Spirochaetaceae and Delftia were enriched and played a dominant role in C-MFC stability and power generation. The promotion by Cupriavidus, Geobacter and Stenotrophomonas in simultaneous OTC degradation and bioelectricity generation in the O-MFC was demonstrated.

Long-term bio-power of ceramic microbial fuel cells in individual and stacked configurations

In order to improve the potential of Microbial Fuel Cells (MFCs) as an applicable technology, the main challenge is to engineer practical systems for bioenergy production at larger scales and to test how the prototypes withstand the challenges occurring during the prolonged operation under constant feeding regime with real waste stream. This work presents the performance assessment of low-cost ceramic MFCs in the individual, stacked (modular) and modular cascade (3 modules) configurations during long term operation up to 19 months, utilising neat human urine as feedstock. During 1 year, the performance of the individual MFC units reached up to 1.56 mW (22.3 W/m3), exhibiting only 20% power loss on day 350 which was significantly smaller in comparison to conventional proton or cation exchange membranes. The stack module comprising 22 MFCs reached up to 21.4 mW (11.9 W/m3) showing power recovery to the initial output levels after 580 days, whereas the 3-module cascade reached up to 75 mW (13.9 W/m3) of power, showing 20% power loss on day 446. In terms of chemical oxygen demand (COD) removal, the 3-module cascade configuration achieved a cumulative reduction of >92%, which is higher than that observed in the single module (56%).

Development of efficient electroactive biofilm in urine-fed microbial fuel cell cascades for bioelectricity generation

The Microbial fuel cell (MFC) technology harnesses the potential of some naturally occurring bacteria for electricity generation. Digested sludge is commonly used as the inoculum to initiate the process. There are, however, health hazards and practical issues associated with the use of digested sludge depending on its origin as well as the location for system deployment. This work reports the development of an efficient electroactive bacterial community within ceramic-based MFCs fed with human urine in the absence of sludge inoculum. The results show the development of a uniform bacterial community with power output levels equal to or higher than those generated from MFCs inoculated with sludge. In this case, the power generation begins within 2 days of the experimental set-up, compared to about 5 days in some sludge-inoculated MFCs, thus significantly reducing the start-up time. The metagenomics analysis of the successfully formed electroactive biofilm (EAB) shows significant shifts between the microbial ecology of the feeding material (fresh urine) and the developed anodic biofilm. A total of 21 bacteria genera were detected in the urine feedstock whilst up to 35 different genera were recorded in the developed biofilm. Members of Pseudomonas (18%) and Anaerolineaceae (17%) dominate the bacterial community of the fresh urine feed while members of Burkholderiaceae (up to 50%) and Tissierella (up to 29%) dominate the anodic EAB. These results highlight a significant shift in the bacterial community of the feedstock towards a selection and adaptation required for the various electrochemical reactions essential for survival through power generation.

Unraveling interactive characteristics of microbial community associated with bioelectric energy production in sludge fermentation fluid-fed microbial fuel cells

This first-attempt study deciphered the interactive characteristics of anodophilic microbial community-associated bioelectricity production in waste activated sludge (WAS) fermentation fluid-fed microbial fuel cells (MFCs). A novel schematic elucidation for illustrating synergistic interactions in anodic microbial consortia towards electrogenesis was proposed. Moreover, the specific genera of Pseudomonas, Desulfovibrio, Phyllobacterium, Desulfuromonas, Chelatococcus and Aminivibrio were dominant in anodic biofilms, leading to an electrogenesis efficiency of 1.254 kWh/kg COD and peak power density of 0.182 W/m² (at feeding level of 1.20 g COD/L). It was apparently higher than those MFCs fed with glucose/acetate. The fermentative species contributed positively in reorganizing microbial community structure in anodic biofilms, positively relating to electrogenesis via interactions with exoeletrogens in MFCs. Finally, a more electrogenesis was positively associated to larger anodic microbial diversity, relatively medium anodic community evenness, together with higher abundance of functional genes related to electrogenesis in functional species in MFCs fed with WAS fermentation fluid.

High-efficiency salt, sulfate and nitrogen removal and microbial community in biocathode microbial desalination cell for mustard tuber wastewater treatment

Considering there is no study involving simultaneous salt, sulfate and nitrogen removal from high-salinity mustard tuber wastewater (MTWW), biocathode microbial desalination cell (BMDC) was first constructed and used to treat MTWW. The results showed that 97.4% of salt, 99.7% of sulfate and 99.8% of nitrogen could be removed from MTWW. The relative abundances of electrgenic bacteria in anode and cathode were 15.95% and 15.10%, respectively, which greatly promoted the electricity generation and desalination. The bacteria involved in sulfate reduction in anode were the dominant population, with relative abundance of 13.94%. Microbial community analysis of cathode biofilm indicated that autotrophic nitrification-anaerobic denitrification, electrochemical reduction and anaerobic ammonium oxidation might coexist for high-efficiency nitrogen removal. Besides, the BMDC showed stable power output for 150 days. These findings provide a promising approach for efficient treatment of MTWW.

Electricity generation, salinity, COD removal and anodic biofilm microbial community vary with different anode CODs in a microbial desalination cell for high-salinity mustard tuber wastewater treatment

A three-chamber microbial desalination cell (MDC) was constructed for high-salinity mustard tuber wastewater (MTWW) treatment. The effect of anode COD on electricity generation, salinity, COD removal and the anodic biofilm microbial community in MDC for the MTWW treatment was investigated. The results showed that electricity generation was better when the anode COD was 900 mg L⁻¹versus when it was 400 or 1400 mg L⁻¹. The ionic strength and conductivity of the anolyte were higher than those at 400 mg L⁻¹; thus, the ohmic internal resistance was lower. In addition, the mass transfer internal resistance was lower than that at 1400 mg L⁻¹, which made the system internal resistance the lowest; consequently, the voltage and power density were the highest. The output voltage, power density and coulombic efficiency of the 1000 Ω external resistors were 555 mV, 3.03 W m⁻³ and 26.5% ± 0.4%, respectively. Desalination was the highest when the anode COD was 400 mg L⁻¹. The lowest ionic strength and osmotic pressure of the anolyte resulted in the strongest osmosis, thereby producing the highest desalination rate; the desalination rate was 5.33 mg h⁻¹. When MDC was coupled with the dual-chamber microbial fuel cell (MFC), the desalinated MTWW could be used as the anode substrate of the MFC; its high COD could be removed continuously, and the COD removal values were 86.2% ± 2.5%, 83.0% ± 2.0% and 84.3% ± 2.4%. High-throughput sequencing analysis indicated that hydrolytic and fermentative bacteria were the core anode bacteria of MDC. The abundances of electrochemically active bacteria in the anode biofilms of the three groups were 11.78% (400 mg L⁻¹ COD), 14.06% (900 mg L⁻¹ COD) and 13.68% (1400 mg L⁻¹ COD). Therefore, the differences in anode CODs impacted the abundance of electrochemically active bacteria, which led to differences in electricity generation performances.

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