Microbial Desalination Cell Research Articles

Investigation of the efficiency of microbial desalination cell in removal of arsenic from aqueous solutions

Microbial desalination cell (MDC) is an environmentally friendly technology and a new method for desalination. The aim of this research is to investigate the extent of removal of arsenic (As) from aqueous solutions by MDC. To examine the efficiency of the process, synthetic As were prepared with concentrations of 100–600 μg/L in deionized water. The removal efficiency was examined at retention times of 30–120 min, at psychrophilic, mesophilic, and thermophilic temperatures and dissolved oxygen of 2–6 mg/L. The real water sample of Bardsir region in Kerman as well as the synthetic wastewater sample was experimented with to examine removal efficiency under the optimal conditions. The optimal conditions for removal of As were obtained as 600 mg/L of As, 6 mg/L of dissolved oxygen, temperature of 25–30 °C, and retention time of 120 min. Under these conditions, As removal efficiency in the synthetic samples of As, real water sample of Bardsir region, and synthetic wastewater sample was obtained as 75, 68, and 56%, respectively. Considering the relatively high efficiency of MDC in removal of As and its advantages including being environmentally friendly and saving energy, it is an effective method in removal of As from aqueous solutions.

Bioremediation of steel plant wastewater and enhanced electricity generation in microbial desalination cell.

Microbial desalination cell (MDC) is a propitious technology towards water desalination by utilizing wastewater as an energy source. In this study, a multi-chambered MDC was used to bioremediate steel plant wastewater using the same wastewater as a fuel for anodic bacteria. A pure culture of Pseudomonas putida MTCC 1194 was isolated and inoculated to remove toxic phenol. Three different inoculum conditions, namely P. putida (INC-A), a mixture of P. putida and activated sludge (INC-B), and activated sludge alone (INC-C) were employed in an anodic chamber to mainly compare the electricity generation and phenol degradation in MDCs. The study revealed the maximum phenol removal of 82 ± 2.4%, total dissolved solids (TDS) removal of 68 ± 1.5%, and power generation of 10.2 mW/m2 using INC-B. The synergistic interactions between microorganisms, can enhance the toxic phenol degradation and also electricity generation in MDC for onsite wastewater application.

Evaluation of anammox biocathode in microbial desalination and wastewater treatment

This study presents the use of an autotrophic microorganism, Anammox bacteria, as a sustainable biocatalyst/biocathode in microbial desalination cells (MDCs) for energy-positive wastewater treatment. We report the first proof of concept study to prove that anammox mechanism can be beneficial in MDCs to provide simultaneous removal of carbon and nitrogen compounds from wastewater while producing bioelectricity. A series of experiments were conducted to enrich and evaluate the anammox mechanism and the process performance in continuous, fed-batch mode conditions. Coulombic efficiency of MDCs and nitrite and ammonium removal of wastewater increased in successive batch studies. A maximum power density of 0.092 Wm−3 (or a maximum current density of 0.814 A m−3) with more than 90% of ammonium removal was achieved in this system. We calculated the Nernst potential for the nitrite reduction in the anammox biocathode chamber and compared with experimental values. Sequential removal of carbon and nitrogen compounds in anode and cathode chambers respectively, was also evaluated. Further, the inhibition effect of high nitrogen concentrations and the variations in microbial community profiles, especially, anammox presence was studied at different carbon and ammonia concentrations. Experimental studies and microbial community analysis are presented in detail.

Microbial desalination cell with sulfonated sodium poly(ether ether ketone) as cation exchange membranes for enhancing power generation and salt reduction

Microbial desalination cell (MDC) is a bioelectrochemical system capable of oxidizing organics, generating electricity, while reducing the salinity content of brine streams. As it is designed, anion and cation exchange membranes play an important role on the selective removal of ions from the desalination chamber. In this work, sulfonated sodium (Na+) poly(ether ether ketone) (SPEEK) cation exchange membranes (CEM) were tested in combination with quaternary ammonium chloride poly(2,6-dimethyl 1,4-phenylene oxide) (QAPPO) anion exchange membrane (AEM). Non-patterned and patterned (varying topographical features) CEMs were investigated and assessed in this work. The results were contrasted against a commercially available CEM. This work used real seawater from the Pacific Ocean in the desalination chamber. The results displayed a high desalination rate and power generation for all the membranes, with a maximum of 78.6±2.0% in salinity reduction and 235±7mWm−2 in power generation for the MDCs with the SPEEK CEM. Desalination rate and power generation achieved are higher with synthesized SPEEK membranes when compared with an available commercial CEM. An optimized combination of these types of membranes substantially improves the performances of MDC, making the system more suitable for real applications.

A review of microbial desalination cell technology: Configurations, optimization and applications

Abstract Seawater could be a potential source of freshwater to manage the intensified demand of drinking water for new generations. The recent techniques for desalination and wastewater treatment are energy intensive and unsustainable. Therefore, an integrated and sustainable approach is essential to achieve cost-effective desalination through wastewater treatment. Microbial desalination cell (MDC) has been proven to be one of the emerging technologies capable of simultaneous wastewater treatment, seawater desalination and eco-energy production. This technique generates electricity through the bio-electrochemical oxidation of organics present in wastewater. The produced electricity is utilized to drive the migration of ions in MDC system. This ionic migration will result in desalination as well as formation of value-added by-products. The review summarizes the recently investigated MDC configurations along with their critical evolution of designs and operational parameters on the desalination and power generation capabilities. The review also acknowledges the emerging applications of MDC for microbial electrochemical desalination, bio-remediation, nutrients recovery, water softening, and value-added chemical production. The key findings included that the MDC system achieved a remarkable desalination without any external power input, and treatment of wastewater, and recovery of power without intermediate steps. The technical challenges associated with their practical applications were maintaining the pH in cathodic and anodic fluids, higher internal resistance, usage of catalysts on electrodes, and membrane fouling and durability. However, for certain configurations especially for microbial electrolysis and desalination cell (MEDC)/microbial electrolysis desalination and chemical production cell (MEDCC), the integration with electrodialysis module can significantly increase their performances. The installation of ED module will establish the pH neutrality and increased water recovery through recirculation of electrolytes between chambers of ED module and these MDC configurations. However, the sustainable development of MDC technology and its scale-up requires future investigations related to prevention of membrane fouling, materials feasibility, electron transfer kinetics, microbial growth and durability of catalyst. The feasibility studies are also needed to be conducted for determining the suitability of MDC operation in terms of reactor performance and stability.

Water deionization with renewable energy production in microalgae - microbial desalination process

Abstract Photosynthetic microbial desalination cells (PMDCs) using microalgae biocathode (Chlorella vulgaris species) were evaluated under three different process configurations. Static (fed-batch, SPMDC), continuous flow (CFPMDC) and a photo-bioreactor MDC (PBMDC), were developed to study the impact of process operation and design on wastewater treatment, water deionization, electricity generation, nutrient removal, and biomass production capacities. The effect of TDS concentration in desalination compartment on the overall performance of SPMDC was also studied. TDS and COD removal rates and power densities have increased with increase in TDS concentrations in the desalination compartment. TDS removal rates were 21.4%, 29%, and 32.2% with corresponding COD removal of 58%, 63%, and 64% at 5 g/L, 20 g/L and 35 g/L respectively. The power densities at these TDS concentrations were 285 mW/m3, 550 mW/m3 and 675 mW/m3 respectively in SPMDCs. Although the electricity production was lower, a higher biomass growth rate of 7 mg L−1 h−1 was recorded for CFPMDC. The COD removal and nutrient removal potentials were similar in all three experimental configurations. Experimental studies show that SPMDCs are more appropriate for bioelectricity production due to biofilm formation while the continuous flow or photobioreactor PMDCs are suitable for microalgae biomass production.

Enhancing forward osmosis water recovery from landfill leachate by desalinating brine and recovering ammonia in a microbial desalination cell

In this work, a microbial desalination cell (MDC) was employed to desalinate the FO treated leachate for reduction of both salinity and chemical oxygen demand (COD). The FO recovered 51.5% water from a raw leachate and the recovery increased to 83.5% from the concentrated leachate after desalination in the MDC fed with either acetate or another leachate as an electron source and at a different hydraulic retention time (HRT). Easily-degraded substrate like acetate and a long HRT resulted in a low conductivity desalinated effluent. Ammonia was also recovered in the MDC cathode with a recovery efficiency varying from 11 to 64%, affected by current generation and HRT. Significant COD reduction, as high as 65.4%, was observed in the desalination chamber and attributed to the decrease of both organic and inorganic compounds via diffusion and electricity-driven movement.

Performance of microbial desalination cell for salt removal and energy generation using different catholyte solutions

Microbial desalination cell (MDC) is a bioelectrochemical process for simultaneous bioelectricity generation, wastewater treatment, and water desalination. The major drawback of MDC improvement is using toxic catholyte solutions which are normally employed in cathode chamber. In this study, the performance of microbial desalination cell using buffer saline solution was investigated for the first time. The obtained results were compared to several low-cost catholyte solutions, including low concentration of phosphate buffer solution (PBS), non-buffer saline solution, and bio-catholyte. All MDC reactors were fed with actual urban wastewater as fuel. Among all examined catholyte solutions, the MDC using bio-catholyte achieved the highest power density of 32.6Wm−3, followed by the MDC using saline buffer catholyte with maximum power density of 29.4Wm−3. Bio-catholyte had also lower internal resistance, and it improved current generation; maximum COD removal and desalination rate were 80% and 0.38g NaClL−1h−1, respectively. On the other hand, in the MDC with buffer saline solution, the COD removal and desalination rate were 73.1% and 0.34g NaClL−1h−1, respectively. In the MDCs using PBS and non-buffer saline solution, maximum power density was 11.1 and 16.3Wm−3, respectively. Based on experimental data, Among the examined catholytes, wastewater as bio-catholyte and saline buffer solution were the desired candidates for MDC scale up, and the most promising point was their being inexpensive alternatives to supplant the costly MDCs catholytes.

Optimizing a concentration of NaCl and 2Na2CO3∙3H2O with microbial desalination cell from the usage of UI lake water

Microbial Desalination Cell (MDC) is one of a Bio Electrochemical technology and also modification technology of Microbial Fuel Cell (MFC), MDC is a method that desalinate a sea water. In the use of this MDC system, the bio electrode that use is from coconut shell charcoal. The use of charcoal as Bio Electrode because it has a low cost as well as environmentally friendly, and charcoal doesn’t have some toxic properties. Another problem besides the use of bio electrode, is the imbalance between the pH and the chamber becomes another obstacle to the MDC system and the impact of some approaches leads to increased cost of capital and operational costs. In order to overcome these barriers by cost, Lake UI is used as the substrate and Sodium percarbonate (SP or 2Na2CO3∙3H2O) also used as a natural buffered electrolyte. Based on the results of variations of SP concentration, best concentration of SP was at 0.15 M (SR=15.14%), concentration NaCl at 35 g/L were able to reduce the mass of 3.626 g to 3.077 g with salinity 30.77 g/L.

Reduction of COD and BOD concentration in lake water of universitas indonesia with microbial desalination cell system and utilizing bio charcoal as electrode

One of the most promising areas with the existence of the lake is Universitas Indonesia. Universitas Indonesia (UI) has six lakes with a total area of 269,107 m2 which is very important for its existence to balance the surrounding environment. Currently, the existence of UI lake has been contaminated with the COD value of about 1 to 8.000 mg/L due to a lot of garbage that enters and buried in it, that more attention is needed so that pollution will not increase. Microbial Desalination Cell (MDC) is a development system of Microbial Fuel Cell (MFC), which has the ability to desalinate seawater and can produce electricity by using microorganisms as waste decomposers. In addition, MDC method can also reduce the level of waste contained in the substrate used. To improve the performance of MDC, this study utilizes bio charcoal from rice husks to assess the performance of sodium percarbonate in the cathode chamber with a variation of 0.05 M concentration; 0.1 M; 0.15 M; and 0.2 M, and the performance of the addition of bacteria consortium on the substrate. The best results of this MDC study, in the variation of 0.15 M sodium percarbonate concentration with a decrease of COD and BOD of 93.98% and 87.67% and in variation of addition of bacteria consortium of 1 mL with decrease of COD and BOD 90.04% and 50.52%.

Effect of the organic load on salt removal efficiency of microbial desalination cell

This work was made possible by NPRP grant # 6-289-2-125 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.

Improved salt removal and power generation in a cascade of two hydraulically connected up-flow microbial desalination cells

ABSTRACTA novel two chamber up-flow microbial desalination cell (UMDC) was designed for evaluating desalination of real seawater with simultaneous wastewater treatment and energy generation. Two UMDCs were hydraulically connected in continuous flow mode (cascade mode) and operated at ten different hydraulic retention times (HRTs) [120 h to 12 h] and salt retention times (SRTs) [40 h to 4 h] for improved performance of chemical oxygen demand (COD) and salt removal. These UMDCs were operated at different combinations of high power (higher external resistance) and high current (low external resistance) mode to find the most suitable conditions for obtaining higher COD removal, salt removal, power production and current generation. The optimum HRT and SRT were 60 h and 40 h, respectively. The highest salt removal achieved was 72% at SRT of 40, while the highest COD removal was 83% at a HRT of 60 h. A maximum current density of 2.375 A/m2 was obtained, while the maximum power density was 5.879 W/m2. The obtained results give an overlook for the scale up of UMDCs in the future. In the entire system, membrane fouling is still a major problem. As the operation time increases, this resulted in low power generation and low salt removal efficiency. The UMDCs can function as sustainable and alternative solution for real wastewater treatment and seawater desalination with resource recovery and power production.

Tetramethyl ammonium hydroxide production using the microbial electrolysis desalination and chemical-production cell with long anode

The aim of this study was to investigate the feasibility to improve the tetramethyl ammonium hydroxide (TMAH) production in the microbial electrolysis desalination and chemical-production cell (MEDCC) with long anode of 48 cm. Different concentrations of tetramethylammonium chloride (0.3–0.7 M) and applied voltages (1.5–3.5 V) were tested in the MEDCC. With 0.6 M of tetramethylammonium chloride as the raw material and under the applied voltage of 3.5 V, the maximum TMAH production rate in the MEDCC reached 1.13 ± 0.12 mmol/h, which was 9.4 times higher than those previously reported in the MEDCCs. The maximum current density of 41.0 ± 4.0 A/m2 in the MEDCC was obtained, which was the highest value in the bioelectrochemical systems using the carbon cloth or carbon brush as the anode so far. Our results should provide a promising method to improve the TMAH production and boost the MEDCC application.

Efficiently "pumping out" value-added resources from wastewater by bioelectrochemical systems: A review from energy perspectives.

Bioelectrochemical systems (BES) can accomplish simultaneous wastewater treatment and resource recovery via interactions between microbes and electrodes. Often deemed as "energy efficient" technologies, BES have not been well evaluated for their energy performance, such as energy production and consumption. In this work, we have conducted a review and analysis of energy balance in BES with parameters like normalized energy recovery, specific energy consumption, and net energy production. Several BES representatives based on their functions were selected for analysis, including direct electricity generation in microbial fuel cells, hydrogen production in microbial electrolysis cells, nitrogen recovery in BES, chemical production in microbial electrosynthesis cells, and desalination in microbial desalination cells. Energy performance was normalized to water volume (kWh m-3), organic removal (kWh kg COD-1), nitrogen recovery (kWh kg N-1), chemical production (kWh kg-1), or removed salt during desalination (kWh kg-1). The key operating factors such as pumping system (recirculation/feeding pumps) and external power supply were discussed for their effects on energy performance. This is an in-depth analysis of energy performance of various BES and expected to encourage more thinking, analysis, and presentation of energy data towards appropriate research and development of BES technology for resource recovery from wastewater.

Improved petroleum refinery wastewater treatment and seawater desalination performance by combining osmotic microbial fuel cell and up-flow microbial desalination cell

ABSTRACTThe petroleum refinery wastewater which is a product of petroleum refinery has a high organic content. This study explores the utilization of petroleum refinery wastewater collected from petroleum refinery as a resource for bioelectricity generation and using this energy for salt removal from seawater in a hydraulically connected osmotic microbial fuel cell (OsMFC) and up flow microbial desalination cell (UMDC). Anaerobic mixed sludge was used in the anodic chamber of OsMFC and UMDC. Petroleum refinery wastewater was fed first into the OsMFC and then transferred to the UMDC. The OsMFC and UMDC were connected to 1000 and 100 Ω external resistance respectively. Experimental results showed that the combined system could remove 93% of chemical oxygen demand (COD) from the petroleum refinery wastewater whilst 48% salts were removed from the seawater. Experimental results showed that this complex wastewater can be treated and produce bioelectricity, with COD removal and salt removal. The hydraulically connected OsMFC and up flow MDC provide a suitable platform for wastewater treatment and seawater desalination.

Investigation of patterned and non-patterned poly(2,6-dimethyl 1,4-phenylene) oxide based anion exchange membranes for enhanced desalination and power generation in a microbial desalination cell

Quaternary ammonium poly(2,6-dimethyl 1,4-phenylene oxide) (QAPPO) anion exchange membranes (AEMs) with topographically patterned surfaces were assessed in a microbial desalination cell (MDC) system. The MDC results with these QAPPO AEMs were benchmarked against a commercially available AEM. The MDC with the non-patterned QAPPO AEM (Q1) displayed the best desalination rate (a reduction of salinity by 53±2.7%) and power generation (189±5mWm−2) when compared against the commercially available AEM and the patterned AEMs. The enhanced performance with the Q1 AEM was attributed to its higher ionic conductivity and smaller thickness leading to a reduced area specific resistance. It is important to note that Real Pacific Ocean seawater and activated sludge were used into the desalination chamber and anode chamber respectively for the MDC – which mimicked realistic conditions. Although the non-patterned QAPPO AEM displayed better performance over the patterned QAPPO AEMs, it was observed that the anodic overpotential was smaller when the MDCs featured QAPPO AEMs with larger lateral feature sizes. The results from this study have important implications for the continuous improvements necessary for developing cheaper and better performing membranes in order to optimize the MDC.

Reduction of organic compounds in petro-chemical industry effluent and desalination using Scenedesmus abundans algal microbial desalination cell

Water and energy shortages are considered to be very serious global issue. As a consequence, it is necessary to develop an alternative water resource such as desalination and wastewater treatment etc. Microbial desalination cell (MDC) is the new, green and environment–friendly technology that desalinates seawater and produces bioelectricity. This study integrate desalination with wastewater treatment and bioelectricity production in MDC by utilizing microalgae as bio-cathode and the results were compared with the chemical cathode. Recently, microalgae have received a high attention for application in bio-electrochemical systems due to its potential to be used for oxygen generation and biodiesel production. The study utilizes petroleum wastewater in the anode chamber and microalgae Scenedesmus abundans in the cathode chamber. The results have highlighted that microalgae bio-cathodes perform better than chemical cathode and increases COD removal and produce a considerable amount of bioelectricity. It also proved that high initial salt concentration 35gNacl L−1desalinates well when compared with low initial salt concentration 20g NaCl L−1 .The maximum voltage and desalination efficiency of MDC 1 (35gNaCl L−1) and MDC 2(20gNaCl L−1) is found to be 654mv and 55.3%; 506mv and 42.6% with the volumetric ratio of 1:0.5:1(anode, desalination chamber and microalgae cathode). Thus the experimental results reveal that utilizing bio-cathode MDC proved to be a promising platform for effective desalination of sea water.

Supercapacitive microbial desalination cells: New class of power generating devices for reduction of salinity content

In this work, the electrodes of a microbial desalination cell (MDC) are investigated as the positive and negative electrodes of an internal supercapacitor. The resulting system has been named a supercapacitive microbial desalination cell (SC-MDC). The electrodes are self-polarized by the red-ox reactions and therefore the anode acts as a negative electrode and the cathode as a positive electrode of the internal supercapacitor. In order to overcome cathodic losses, an additional capacitive electrode (AdE) was added and short-circuited with the SC-MDC cathode (SC-MDC-AdE). A total of 7600 discharge/self-recharge cycles (equivalent to 44 h of operation) of SC-MDC-AdE with a desalination chamber filled with an aqueous solution of 30 g L−1 NaCl are reported. The same reactor system was operated with real seawater collected from Pacific Ocean for 88 h (15,100 cycles). Maximum power generated was 1.63 ± 0.04 W m−2 for SC-MDC and 3.01 ± 0.01 W m−2 for SC-MDC-AdE. Solution conductivity in the desalination reactor decreased by ∼50% after 23 h and by more than 60% after 44 h. There was no observable change in the pH during cell operation. Power/current pulses were generated without an external power supply.

Coupling microfiltration membrane with biocathode microbial desalination cell enhances advanced purification and long-term stability for treatment of domestic wastewater

In this study, a hollow fiber microfiltration membrane (HFM) coupled biocathode microbial desalination cell (MDC) was fabricated. With real wastewater flowing serially from anaerobic anode to oxic biocathode, filtered by the HFM and finally to the central membrane stack, the HFM-MDC took advantages of conventional anaerobic/oxic process, membrane biofilm reactor, and eletrodeionization technology, realizing advanced removal of organics, suspended solids, and salinity during 105 days of operation. The produced diluate was 86.1v%, with final conductivity, chemical oxygen demand, total nitrogen, and total phosphorus (TP) reaching 59.2 ± 12.2μS/cm, 35.5 ± 4.0mg/L, 1.65 ± 0.39mg/L, and 0.14 ± 0.05mg/L respectively. The corresponding concentrate (13.9v%) concentrated 6.7 times the initial conductivity (6044 ± 168μS/cm), recovered 98.7% of phosphorous (TP of 40.9 ± 4.9mg/L) and part of nitrogen. In addition, the HFM was stably operated for 105 days due to coefficient aeration flushing and regular chemical backwashing, with trans-membrane pressure keeping at ≤ 15kPa for most of time. Moreover, this integrated process only needs wastewater as sole water input, and possesses a relative cheap HFM coupled biocathode compared with conventional Pt cathode, providing a promising solution for practical application of MDC in wastewater purification.

Unravelling and Reconstructing the Nexus of Salinity, Electricity, and Microbial Ecology for Bioelectrochemical Desalination.

Microbial desalination cells (MDCs) are an emerging concept for simultaneous water/wastewater treatment and energy recovery. The key to developing MDCs is to understand fundamental problems, such as the effects of salinity on system performance and the role of microbial community and functional dynamics. Herein, a tubular MDC was operated under a wide range of salt concentrations (0.05-4 M), and the salinity effects were comprehensively examined. The MDC generated higher current with higher salt concentrations in the desalination chamber. When fed with 4 M NaCl, the MDC achieve a current density of 300 A m-3 (anode volume), which was one of the highest among bioelectrochemical system studies. Community analysis and electrochemical measurements suggested that electrochemically active bacteria Pseudomonas and Acinetobacter transferred electrons extracellularly via electron shuttles, and the consequent ion migration led to high anode salinities and conductivity that favored their dominance. Predictive functional dynamics and Bayesian networks implied that the taxa putatively not capable of extracellular electron transfer (e.g., Bacteroidales and Clostridiales) might indirectly contribute to bioelectrochemical desalination. By integrating the Bayesian network with logistic regression, current production was successfully predicted from taxonomic data. This study has demonstrated uncompromised system performance under high salinity and thus has highlighted the potential of MDCs as an energy-efficient technology to address water-energy challenges. The statistical modeling approach developed in this study represents a significant step toward understating microbial communities and predicting system performance in engineered biological systems.