Microbial Desalination Cell Research Articles

Underpinning the Role of Nanofiltration and Other Desalination Technologies for Water Remediation and Brine Valorization: Mechanism and Challenges for Waste‐to‐Wealth Approach

Desalination brine can negatively impact the marine environment in several ways, although there are ongoing discussions regarding the severity and magnitude of environmental effects. A fascinating strategy to lessen any adverse effects is to undertake resource recovery from the brine, which also has the potential for additional revenue generation. More recently, the increasing demand for secure and less geographically restricted sources of precious or rare earth minerals, integrated with growing awareness of waste management and environmental sustainability, is driving the development of economically viable technologies to recover valuable materials from waste streams. This article provides an overview of different methods and technologies, including reverse osmosis (RO), electrodialysis (ED), and distillation, that can be used to recover precious materials, including Li, Mg, Na, and Rb and valuable blends from various waste sources and thus create a more sustainable and circular economy. The mechanisms are discussed in detail, including electrochemical processes (electrolysis, ED, and capacitive deionization), thermal desalination (multistage flash distillation and membrane distillation), pressure‐driven desalination (RO and nanofiltration), and microbial desalination cells. Challenges associated with recovering precious materials from waste streams, such as fouling, scaling, and environmental impact, along with further research directions and potential applications of desalination technologies, are also addressed.

Effect of electron acceptors on electricity production and desalination of caspian sea water using microbial desalination cells

ABSTRACT The Microbial Desalination Cell (MDC) stands out as an innovative and a sustainable technology for both renewable energy generation and water treatment. The choice of electron acceptor significantly influences the efficiency of electricity flow. This study focuses on exploring the MDC performance under different conditions, including variations in cathode electron acceptors, initial pH levels, and hydraulic retention time (HRT). The investigation assesses simultaneous reduction of TDS and power generation from Caspian Sea water, a prominent saline water source in northern Iran, in both open-circuit (OC) and closed-circuit (CC) modes. The findings reveal that sodium hypochlorite, potassium permanganate, and potassium bromate as catholyte achieved TDS reduction rates of 84%, 77%, and 72%, respectively, under CC conditions at pH 5. Furthermore, it was observed that increasing HRT and pH levels lead to a decrease in desalination efficiency and power generation. Notably, the study highlights that the maximum power density was attained using permanganate, hypochlorite, and bromate as catholyte in both OC and CC configurations. By showcasing the adaptability of MDC performance with different cathode electron acceptors under varying conditions, this research offers valuable insights for optimizing MDC efficiency when treating real saline water sources.

Investigating the performance of CoFe2O4@TiO2 nanomaterial as multifunctional cathode catalyst for simultaneous dye degradation and oxygen reduction in microbial desalination cell

Microbial desalination cell (MDC) is an emerging technology in which water is desalinated and energy is generated by the breakdown of organic compounds and catalyzed by microorganisms using the potential gradient created in the reactor. MDC efficacy is substantially influenced by the oxygen reduction reaction (ORR) occurring at the cathode, albeit potential hindrances include sluggish reaction rates and biofouling development. The present study involved synthesizing and utilizing CoFe2O4@TiO2 nanocomposite as a multifunctional catalyst on a cathode surface for efficient ORR and dye removal. XPS, HRTEM, and XRD techniques were used to ascertain the NPs' morphology, surface properties, dimensions, and XRD patterns. Physicochemical investigation showed that the nanoparticles had a consistent distribution, a mean diameter of 18.11 nm, and a spherical shape. Researchers tested MDCs with nanoparticles (NPs). The highest power density was 4.56 W/m3, 50 % more than the MDC with a lower loading density. The desalination efficiency was found to be 60 % at 1.5 mg/cm2 CoFe2O4@TiO2, however, it was 80 and 81 % at 2.5 and 2.0 mg/cm2 catalyst concentrations, respectively. The dye degradation efficiency of as high as 88 % was observed with CoFe2O4@TiO2 nanocomposite cathode MDC. The findings show that CoFe2O4@TiO2 nanocomposite might be an economically feasible ORR catalyst, improving MDC efficiency and cost.

Microbial electrochemical enhanced composting of sludge and kitchen waste: Electricity generation, composting efficiency and health risk assessment for land use

To realize the energy and resource utilization from organic solid waste, a two-phase microbial desalination cell (TPMDC) was constructed using dewatered sludge and kitchen waste as the anode substrate. The performance of electricity generation and composting efficacy was investigated, along with a comprehensive assessment of the potential health risks associated with the land use of the resulting mixed compost products. Experimental outcomes revealed a maximum open-circuit voltage of 0.893 ± 0.005 V and a maximum volumetric power density of 0.797 ± 0.009 W/m³. After 90 days of composting enhanced by microbial electrochemistry, a significant organic matter removal rate of 31.13 ± 0.44 % was obtained, and the anode substrate electric conductivity was reduced by 30.02 ± 0.04 % based on the anode desalination. Simultaneously, there was an increase in the content of available nitrogen, phosphorus, and potassium, as well as an improvement in the seed germination index. The forms of heavy metals shifted from bioavailable to stable residual states. The non-carcinogenic hazard index (HI) values for heavy metals and polycyclic aromatic hydrocarbons (PAHs) during the land use of compost products were less than 1, and the total carcinogenic risk (TCR) values for heavy metals and PAHs were below the acceptable threshold of 10−4. The occupational population risk of infection from five pathogens was higher than that of the general public, with all risk values ranging from 8.67 × 10−8 to 1, where the highest risk was attributed to occupational exposure to Legionella. These outcomes demonstrated that the mixture of dewatered sludge and kitchen waste was an appropriate anode substrate to enhance TPMDC stability for electricity generation, and its compost products have promising land use suitability and acceptable land use risk, which will provide important guidance for the safe treatment and disposal of organic solid waste.

CuO vs. AgO: A comparative study of cathode catalysts for boosting oxygen reduction in microbial desalination cells

Microbial Desalination Cell (MDC) is an innovative approach for water desalination that concurrently produces energy through the process of substrate oxidation. The primary issue of the technique is its limited power on capabilities during the oxygen reduction reaction (ORR). While the depletion of oxygen is a significant process in electrochemical energy conversion, its slow kinetics hinder its utilization in MDCs. One potential resolution to this problem is the utilization of a cathode catalyst with a high level of activity, which effectively enhances the rate of ORR. Different concentrations of copper oxide (CuO) nanoparticles (NPs) were used to investigate the behavior of ORR and its impact on the performance of the MDC. The optimal concentration of silver oxide (AgO) NPs was utilized to conduct a comparative analysis of both types of NPs. The size of CuO NPs and AgO NPs was found to be 65 nm and 55 nm respectively by material characterization studies. The power density achieved in the absence of the catalyst was 1.1 W/m3, and this value increased to 4.9 W/m3 with the incorporation of 3 mg/cm2 AgO. The use of a catalyst loading of 3 mg/cm2 has been determined to be efficacious in enhancing the desalination rate in MDC. The electrochemical investigations conducted also showed an improvement in the electrocatalytic behavior of cathodic kinetics while operating under these specific afterward. Therefore, the utilization of AgO catalyst exhibits potential as a viable option for the expansion of MDC processes, thereby contributing to the achievement of sustainable development objectives.

Improved bioenergy recovery and desalination efficiency using innovative configuration of an upflow triple enclosed cuboid compartments -photosynthesis microbial desalination cell: Experimental and modeling study

Performance of an innovative configuration of enclosed cuboid compartments-photosynthesis microbial desalination cell (EC-PMDC) for synchronous sewage treatment, desalination of seawater, and renewable energy recovery. Bioanode and biocathode were inoculated with jumbled bacterial species and mixed microalgae, respectively. The results demonstrated that maximum removal efficiency of organic content as chemical oxygen demand (COD) from the sewage was up to 99 %, whereby the total dissolved solids (TDS) removal efficiency from seawater was 91 %, accompanied with maximum power generation of 975 mW/m3. Kinetic study of bacterial growth in the EC-PMDC demonstrated excellent agreement between experimental data and those predicted by Blackman, Monod, Moser, and Teissier models with coefficients of determination (R2) equal to 0.98, 0.97, 0.96, and 0.97, respectively. Significant harmonization was obtained between the experimental results of voltage, current density, and power density with those predicted by the adopted electrochemical model. For comparison purposes, a conventionally designed photosynthesis microbial desalination cell (SC-PMDC) consisted of triple sequential cuboid compartments was setup. It was fed with similar influents as for the EC-PMDC. Maximum efficiencies of COD and TDS removals were 99 % and 81 %, respectively accompanied with power recovery of 420 mW/m3 were observed in the SC- PMDC indicating the superiority of EC-PMDC design.

Investigating and Improving Microbial Desalination Cell Performance Using Potassium Ferricyanide as a Chemical Catholyte

Investigating and Improving Microbial Desalination Cell Performance Using Potassium Ferricyanide as a Chemical Catholyte

Enhancing pollutant removal and desalination in microbial desalination cells using a rotating algal biofilm cathode

Currently, most photosynthetic microbial desalination cells (PMDCs) employ suspended algae as cathode organisms to produce oxygen. However, this method requires expensive platinum as a catalyst to catalyze the binding of oxygen to cathode electrons. In this study, a PMDC using a rotating algal biofilm (RAB) as a biocathode was demonstrated. RAB not only generates enough oxygen as an electron acceptor but also enhances the combination of oxygen and electrons on the cathode. Furthermore, the RAB-MDC system exhibited excellent performance in pollutant removal and desalination. When using simulated wastewater as anolyte and catholyte, the RAB-MDC achieved impressive removal efficiencies for COD, TOC, and NH4+-N, reaching 91.0 ± 0.1 %, 74.7 ± 0.03 %, and 95.0 ± 0.05 %, respectively. The power density reached 89.5 mW/m3 at an external resistance of 1000 Ω, while the desalination efficiency was 36.0 %, with a desalination rate of 190.9 mg/d. Additionally, high-throughput 16S rDNA sequencing was employed to assess the relative abundance of microorganisms in the RAB-MDC device, facilitating guided culture in subsequent studies. In conclusion, this research demonstrates the potential of RAB as a biocathode in MDCs for comprehensive wastewater treatment, desalination, power generation, and nutrient recovery.

An extended bio-electrochemical model for wastewater treatment and water desalination: Insights into the performance of microbial desalination cells

This paper presents an extended mathematical model for a microbial desalination cell (MDC), integrating Haldane kinetics for substrate inhibition and proton translocation theory for substrate dissociation under dynamic flow. The model is capable of predicting exoelectrogenic and methanogenic biomass dynamics, acetate removal efficiencies, salt concentration changes, and current production. Notably, it can be used to explore the influence of operational parameters such as dilution rates, temperatures, and external resistances. Our simulations reveal the optimal conditions for maximizing exoelectrogen concentration (500 mg/L) with minimal methanogen presence (50 mg/L) in the anode chamber at an anolyte dilution rate of 0.5 d−1, a temperature of 20 °C, and an influent acetate concentration of 1500 mg/L. The model accurately predicts the salt reduction in the middle chamber (from 0.2 to 0.09 mol/L) with a salt dilution rate of 0.5 d−1 and an external resistance of 20 Ohm. The model predicts a peak power output of 2.5 mW at external resistances between 20 and 50 Ohm. The model was validated against a suite of experimental literature data, including our previously published lab-scale studies, verifying its accuracy in predicting organic and salt removal rates, current production, and desalination efficiency. This extended model is a valuable tool for understanding the complex interactions between factors that influence MDC performance and can guide the optimization of MDC design for wastewater treatment and desalination.

Utilizing Vigna mungo wash water for simultaneous power generation and desalination using two distinct anodes in a microbial desalination cell

AbstractThis study aims to improve the performance of microbial desalination cell (MDC) using Vigna mungo (Black gram) wash water, reported for the first time as an anolyte utilizing a graphite plate and carbon brush as the anode. Power generation was facilitated by the exoelectrogen, Shewanella putrefaciens MTCC 8104. Polarization studies revealed that the graphite plate MDC attained a high power density of 2720 ± 50 μW/m2 compared to carbon brush for two electrode pairs. The COD removal and desalination efficiency were better for carbon brush MDC, achieving 58.17 ± 2% and 38.14 ± 2% removal, respectively. Power production can be enhanced by increasing the cathode's ability to accept the electrons, reducing the ageing of biofilm and promoting complete oxidation of the substrates. Upon improving its performance, MDC can act as a sustainable technology, collaborating with industries seeking solutions for wastewater treatment, energy generation and agricultural sectors on a large scale.

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

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

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

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

Optimal 4E evaluation of an innovative solar-wind cogeneration system for sustainable power and fresh water production based on integration of microbial desalination cell, humidification- dehumidification, and reverse osmosis desalination

Reliable freshwater production is vital for tackling two of the most critical challenges the world is facing today: climate change and sustainable development. Present work presents an innovative cogeneration system based on solar and wind energies for sustainable production of freshwater, power, and wastewater treatment. For freshwater production and wastewater treatment in this system, the integration of a microbial desalination cell with a humidification-dehumidification and reverse osmosis desalinations has been used. The mentioned systems provide their heat demand from solar energy, and when solar radiation is unable to provide this heat, a hydrogen internal combustion engine drive produces the required heat for the freshwater plant. Excess heat from the hydrogen internal combustion engine is fed into the organic Rankine cycle for more power generation in the whole system to reduce system waste heat and increase efficiency. PEM electrolyzer has been used to supply the hydrogen needed by the internal combustion engine, and this system uses wind turbines to supply the power demand. To evaluate the performance of the whole system, energy, exergy, exergeoeconomic, and exergoenvironmental (4E) analyses have been carried out. Finally, to improve the performance parameters of the system, multi-objective optimization using the Salp swarm algorithm has been used. Investigation of the results show that the proposed system can produce 720 kW of electricity and 5.36 m3/h of freshwater. The energy efficiency of the system is 22.09 %, and its overall cost rate and overall environmental impact rate are 540.33 $/hr and 17.37 Pt/h, respectively. Among the qualitative results obtained in this research, it is possible to mention the high exergy destruction, cost destruction, and environmental impact destruction of the internal combustion engine compared to other equipment used in the proposed system, and this point shows the need to improve this equipment, similar to previous researches. The five-objective optimization results of the proposed system showed that the performance parameters of the system, such as polygeneration energy efficiency, total cost rate, and total environmental impact rate, can be improved by 6.2 %, 1.44 %, and 0.52 %, respectively. The payback period of the proposed system in the optimal state is 6.95 years.

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

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

Role of microbial electrolysis desalination cell in sustainable water and energy management: Performance assessment of platinum and nickel foam cathodes and simulating integration with reverse osmosis systems

This research introduces the microbial integrated cell (MIC), a bioelectrochemical system that combines microbial electrolysis and desalination for sustainable energy and water purification. Efficiency evaluations of nickel foam and Pt/CC cathodes for hydrogen production and desalination showed nickel foam achieving a 91% desalination efficiency, closely following Pt/CC's 99%, with hydrogen generation rates of 0.96 m3H2/m3/d for Pt/CC cathodes and 0.72 m3H2/m3/d for nickel foam. Despite marginally lower performance, the cost advantages of nickel foam suggest its feasibility for large-scale deployment. Further exploration into MIC integration with reverse osmosis (RO) system aims to enhance the sustainability of the combined system. Simulation outcomes indicate that MIC-RO integration can significantly reduce energy consumption and brine concentration discharged into the sea, highlighting its potential to improve desalination plants' efficiency and environmental impact. This research facilitates the transition of these green technologies to practical applications, optimizing efficiency and environmental benefits.

Microalgae Growth in a Biocathode-Photosynthesis Microbial Desalination Cell: Molecular Characterization, Modeling Study, and Performance Evaluation

This study aimed to comprehensively characterize and identify microalgae inhabiting the biocathode compartment of a photosynthetic microbial desalination cell (PMDC). Also, modeling of microalgae growth in the biocathode was considered as well as the interrelation between the growth of microalgae and dissolved oxygen (DO) generation within the biocathode. The general performance of the PMDC was evaluated based on; (1) organic content removal from the real domestic wastewater fed to the anode compartment, (2) salinity removal from actual seawater in the desalination compartment, and (3) power generation in the PMDC. The results unveiled the presence of two distinct microalgae species, specifically Coelastrella sp. and Mariniradius saccharolyticus, which were thoroughly characterized using 16S rRNA and ITS gene sequencing within the cathodic chamber of the PMDC. Following sequence editing and trimming, the resulting sequences were meticulously submitted to the NCBI GenBank and juxtaposed with other sequences utilizing the GenBank online BLAST software. Importantly, the obtained data demonstrated a good correlation with coefficients of determination (R²) reaching 0.83, as per the employed kinetic models. Complete removal of up to 99.11% of organic content from the real domestic wastewater was obtained in the PMDC system with maximum efficiency of desalination elimination of 80.95% associated with a maximum power output of 420 mW/m3 in the system.

Enhancing microbial desalination cell performance through co-culture optimization and response surface methodology (RSM) in high saltwater feed concentration

In response to contemporary water and energy supply challenges, the Microbial Desalination Cell (MDC) emerged as an innovative solution, generating electricity and desalting saline water through wastewater treatment. However, the accumulation of ions during the desalination process adversely affects the biocatalyst performance, imposing scalability limitations on the technology. This study focused on enhancing the system's performance by co-culturing Shewanella oneidensis MR–1 and Escherichia coli. Through the response surface methodology, the effects of organic matter concentration and saltwater feed salinity were systematically investigated by central composite design. The study emphasizes the significant impact of studied factors on system performance. Elevated sodium lactate, sodium acetate concentrations, and salinity positively influence the desalination rate, with NaCl concentration showing an interaction effect with lactate. Positive linear relationships for OCV are observed with lactate and acetate. All factors significantly impact power output, with lactate having the most potent positive effect. Additionally, positive contributions to COD removal are noted for lactate and NaCl concentration and a positive interaction effect. These achievements facilitated the development of a mathematical model to optimize system performance by leveraging co-cultured inoculum and strategic environmental manipulation, overcoming limitations from ion accumulation, and opening the path for further advancements in this field.

Recent progress in the characterization and application of exo-electrogenic microorganisms.

Exo-electrogenic microorganisms are characterized by their special metabolic capability of transferring metabolic electrons out of their cell, into insoluble external electron acceptors such as iron or manganese oxides and electrodes, or vice versa take up electron from electrodes. Their conventional application is primarily limited to microbial fuel cells for electrical power generation and microbial electrolysis cells for the production of value-added products such as biohydrogen, biomethane and hydrogen peroxide. The utility of exo-electrogenic organisms has expanded into many other applications in recent times. Such examples include microbial desalination cells, microbial electro-synthesis cells producing value-added chemicals such as bio-butanol and their applications in other carbon sequestration technologies. Additionally, electrochemically-active organisms are now beginning to be employed in biosensor applications for environmental monitoring. Additionally, the utility of biocathodes in bio-electrochemical systems is also a novel application in catalyzing the cathodic oxygen reduction reaction to enhance their electrochemical performance. Advances have also been made in the expansion and use of other organisms such as the usage of photosynthetic microorganisms for the fabrication of self-sustained bio-electrochemical systems. This review attempts to provide a comprehensive picture of the state-of the art of exo-electrogenic organisms and their novel utility in bioelectrochemical systems.

Harnessing exoelectrogens in a novel microbial desalination cell: a study on the impact of salinity on sago effluent treatment and power generation

The impact of salinity on the performance of exoelectrogens in the novel MDC was studied. MDC – 1 performed better at 30 g L−1 NaCl concentration and MDC – 2 performed better in brackish water.

Resource-efficient nitrogen and salinity removal in a synergistic partial nitritation-anammox bioelectrochemical system

We investigated the performance of a two-stage partial-nitritation-anammox biocathode integrated microbial desalination cell (TNiAmoxMDC) for concurrent nitrogen removal, desalination, and bioelectricity generation at different aeration rates in the nitritation chamber. The TNiAmoxMDC system achieved a maximum total nitrogen removal rate of 50.4 ± 8.2 g-TN/m3/d with 300 mW/m2 of maximum power production utilizing 500 mg/L of glucose chemical oxygen demand (COD) in the anode. The organic removal in the anode chamber showed a good fit to first order reaction model with a rate constant of 0.036 h−1. The biocatalytic activity of anammox bacteria in the biocathode produced a current density of 0.7 A/m2 in the absence of oxygen. More than 98% of the salinity was removed at a rate of 1.48 mg/h. The energy consumption values for nitrogen removal at aeration rates of 0.7, 2.2, and 10 ml/min were 0.022, 0.55, and 0.20 kWh/kg-N, respectively. The maximum energy produced by the TNiAmoxMDC was 0.0157 kWh/m3. Excluding the energy consumption by the system, the net energy recovery was 0.0023 kWh/m3 at an airflow rate of 10 ml/min. Thus, the integration of the partial nitritation-anammox process with microbial desalination cell (MDC) provides energy-and resource-efficient synergy for bioelectrochemical wastewater treatment.