Working Principle and Application of Microbial Fuel Cell

Value added products from wastewater using bioelectrochemical systems: Current trends and perspectives

Petroleum refining, not only consumes large quantities of water but also generates large quantities of wastewater. Large quantities of petroleum refinery wastewater are generated worldwide, approximately 3.5–5 m3 of wastewater generated per ton of crude oil processed. This wastewater is considered as a major source of environmental pollution. Various chemical and biologically based technologies have been developed for the treatment of petroleum refinery wastewater such as reverse osmosis, membrane filtration, electrocoagulation, anaerobic tank, anaerobic baffled reactor, aerated filter and bio-contact oxidation. In the last decade, biological treatment methods of petroleum refinery wastewater were developed because of the high cost of chemical treatment methods and these methods are also more environmental friendly.In this study, we demonstrate for the first time that it is possible to remove salt from saltwater and generate electricity while using petroleum refinery wastewater as an anodic substrate in the three chamber microbial desalination cell (MDC). MDC insinuates a new method for treating petroleum refinery wastewater and concurrently salt removal from seawater with bioelectricity generation. MDC was developed from microbial fuel cell (MFCs) concept. In this device, desalination and wastewater treatment are conducted in one system. MDC has an enormous potential as a low-cost desalination process with wastewater treatment and other benefits. MDC is a new technique in which saltwater can be desalinated without using any external energy source. The exoelectrogenic-bacteria are used in MDC reactor to oxidize biodegradable substrate in the anodic chamber and transfer the produced electrons to the anode electrode.In this study, petroleum refinery wastewater was treated in MDC using three different initial salt concentrations of 5 g/l, 20 g/L and real seawater in desalination chamber along with two separate catholyte (phosphate buffer solution and acidified water). All the three chamber MDC operations were carried out in batch mode. The maximum % COD removals of 71 and 64 were obtained using initial salt concentration of 20 g/L with MDC operated with acidified and phosphate buffer solution as catholyte respectively. The maximum desalination efficiency of 19.9% and 19.1 % were obtained in MDC operated with real seawater using PBS and acidified water as catholyte respectively. The scanning electron microscope images investigation confirmed the presence of microbial biofilm on the anode electrode and anion exchange membrane surface. The MDC performed better with acidified water compared to PBS as catholyte. The above obtained results demonstrated the feasibility of using MDC technologies to generate bioelectricity, seawater desalination and simultaneously treat complex petroleum refinery wastewater, although further studies are required to scale up and optimize the process. The MDCs are emerged as a self-energy driven device for wastewater treatment and seawater desalination at the lab scale. But still MDCs needs further research before it can be implemented at large scale. Acknowledgements: 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.

Exogenous electric field as a biochemical driving factor for extracellular electron transfer: Increasing power output of microbial fuel cell

Microbial electro deionization for waste water treatment – A critical review on methods, applications and mechanism

Chapter 9 - Robust application of microbial electrochemical technology coupled with constructed wetla

Microbial desalination cells for improved performance in wastewater treatment, electricity production, and desalination

Anaerobic digestion is extensively used to recover energy from municipal waste and animal manure. The liquid effluent of anaerobic digestion typically contains high concentrations of ammonium, phosphorus, and divalent cations, which can potentially be recovered by precipitation of sparingly soluble phosphate salts [1-5]. The majority of processes focus on struvite (magnesium ammonium phosphate) crystallization, as both nitrogen and phosphorus are removed and struvite is salable as slow-release plant fertilizer. The potential economics of recovering renewable sources of nitrogen and phosphorus have led to development of various phosphate salt crystallization systems [5-7]. Fluidized bed reactors (FBRs) are commonly used for crystallized phosphate recovery because the design creates an abundance of reactive surface area and solution turbulence [8], enhancing nucleation kinetics and agglomeration. Despite generally high nutrient recovery efficiencies in FBRs, the economic favorability of phosphate salt crystallization systems could be significantly enhanced by increasing the operating pH within the FBR to near the minimum solubility point of struvite (pH = 9 [3]) Sodium hydroxide (NaOH) is often used in research-scale investigation of these technologies because it is highly soluble and can rapidly increase the solution pH [4,7,9,10]. However, such chemical addition approaches can drive up phosphorus recovery costs (as high as $3,500/ton-P) significantly beyond the value of nutrients contained in struvite (~$765/ton-P) [3,11]. Recently, microbial electrochemical technologies (METs), such as microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) have garnered interest as a chemical-free and energy efficient method of enhancing struvite precipitation [12-14]. METs consist of an anode, where anaerobic microbes oxidize organic matter and transfer electrons to an external circuit, and a cathode where the electrons and protons catalytically combine by reducing oxygen to water (MFC) or producing hydrogen gas (MEC). This talk will discuss preliminary results from a bench-scale MEC-FBR system (Figure 1) that demonstrate the potential for an MEC to enable economical pH control in an FBR struvite precipitation system. Net alkali generation rates of approximately 2.3 ± 1.5 mmol m- 2 h-1 were observed in both DC and pulsed-potential MEC tests, which are of reasonable magnitude for typical applications. When only the electrical power input is considered, these experimental data translate to a per-mole cost of alkali generated by an MEC (~7¢ mol-1) that is an order of magnitude lower than the cost of purchased NaOH (~87¢ mol-1). A preliminary net present value (NPV) analysis of the entire MEC unit operation, including both capital and operating costs, suggests a reasonable rate of return can likely be achieved. As well, the data provide preliminary indication of the possibility of further cost advantages from the use of pulsed MEC potentials. The authors acknowledge financial support from USEPA Contract No. EP-D-17-006.

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.

Chapter 12 - Microbial Fuel Cells and Wastewater Treatment

Process optimization for simultaneous antibiotic removal and precious metal recovery in an energy neutral process

Anode-biofilm electron transfer behavior and wastewater treatment under different operational modes of bioelectrochemical system

Developing high surface area catalysts is an effective strategy to enhance the oxygen reduction reaction (ORR) in the application of microbial fuel cells (MFCs). This can be achieved by developing a catalyst based on metal-organic frameworks (MOFs) because they offer a porous active site for ORR. In this work, a novel in situ growth of 2D shell nanowires of ZIF-67 as a template for N-doped carbon (Co/NC) via a carbonization route was developed to enhance the ORR performance. The effects of different reaction times and different annealing temperatures were studied for a better ORR activity. The growth of the MOF template on the carbon cloth was confirmed using scanning electron microscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared. The Co/NC-800 exhibited an enhancement in the ORR activity as evidenced by an onset potential and half-wave potential of 0.0 vs V Ag/AgCl and -0.1 vs V Ag/AgCl, respectively, with a limited current density exceeding the commercial Pt/C. Operating Co/NC-800 on MFC revealed a maximum power density of 30 ± 2.5 mW/m2, a maximum current density of 180 ± 2.5 mA/m2.

With the growing energy crisis, industrialization, rapid urbanization, and increased population, it is necessary to sort out environmental pollution and energy crisis issues. The detection of newly identified or emerging contaminants (ECs) into our aquatic environment is of serious concern for the health and safety of the whole ecosystem, and the existing conventional wastewater (WW) treatment processes are not designed to treat these unidentified contaminants. In this context, Bio-electrochemical systems such as microbial fuel cells (MFCs) are considered a prospective technology in removing these ECs and electricity generation from WW through microbial metabolisms. The MFC unit includes an anode, cathode, cation-sensitive membrane, and an external wire. MFCs have shown significant advantages, including converting substrate into energy, operating at wide ranges of temperature and pH with diverse biomass, generating a meager amount of activated sludge from WW, and zero energy requirement for aeration. Additionally, MFCs have been seen as a resolution for water and energy issues due to their capability to treat WW and electricity generation. However, MFCs have numerous challenges in-field applications, such as turbulence in each compartment, membrane resistance in the proton transportation process, etc. This chapter focuses on the application of MFCs towards the removal of various ECs from the aqueous environment. Applications of MFC technology can also be worked in its power generation ability and sustainable energy generation. Although the current applications of MFC technology are still at the laboratory level, it has a great potential for commercial applications in the near future.KeywordsMicrobial fuel cellActivated sludgeEmerging contaminantsMicrobial metabolismsAntibioticsWastewater

A national energy crisis has emerged in South Africa due to the country’s increasing energy needs in recent years. The reliance on fossil fuels, especially oil and gas, is unsustainable due to scarcity, emissions, and environmental repercussions. Researchers from all over the world have recently concentrated their efforts on finding carbon-free, renewable, and alternative energy sources and have investigated microbiology and biotechnology as a potential remedy. The usage of microbial electrolytic cells (MECs) and microbial fuel cells (MFCs) is one method for resolving the problem. These technologies are evolving as viable options for hydrogen and bioenergy production. The renewable energy technologies initiative in South Africa, which is regarded as a model for other African countries, has developed in the allocation of over 6000 MW of generation capacity to bidders across several technologies, primarily wind and solar. With a total investment value of R33.7 billion, the Eastern Cape’s renewable energy initiatives have created 18,132 jobs, with the province awarded 16 wind farms and one solar energy farm. Utilizing wastewater as a source of energy in MFCs has been recommended as most treatments, such as activated sludge processes and trickling filter plants, require roughly 1322 kWh per million gallons, whereas MFCs only require a small amount of external power to operate. The cost of wastewater treatment using MFCs for an influent flow of 318 m3 h−1 has been estimated to be only 9% (USD 6.4 million) of the total cost of treatment by a conventional wastewater treatment plant (USD 68.2 million). Currently, approximately 500 billion cubic meters of hydrogen (H2) are generated worldwide each year, exhibiting a growth rate of 10%. This production primarily comes from natural gas (40%), heavy oils and naphtha (30%), coal (18%), electrolysis (4%), and biomass (1%). The hydrogen produced is utilized in the manufacturing of ammonia (49%), the refining of petroleum (37%), the production of methanol (8%), and in a variety of smaller applications (6%). Considering South Africa’s energy issue, this review article examines the production of wastewater and its impacts on society as a critical issue in the global scenario and as a source of green energy.

Abstract. Microbial fuel cells (MFCs) can be used for electricity generation. The need for an economic way to reclaim fresh water from seawater is growing in many parts of the world. Modification of microbial fuel cells into desalinating microbial fuel cells is an effort to enhance utility of this technology. This study examines adding a middle, third, desalination chamber to a standard two-chambered microbial fuel cell. Biological and chemical catholytes were compared for desalination and power generation efficiency. Successful results have been obtained in three chamber desalinating microbial fuel cells (MDCs). Rumen microorganisms have been used as exoelectrogens in the MFC's anodic chamber. Glucose was employed as substrate. Nanochloropsis salina, a type of marine algae, and potassium ferricyanide (KFe(CN)6) were used in the cathodic chamber. The central, desalination chamber contained synthetic sea water composition. The system was operated in fed batch mode. Biomass, measured in terms of protein content and chemical oxygen demand (COD), was monitored to maintain the operating conditions. Power generation and desalination were monitored to compare the efficiency of catholytes. The observations revealed that the chemical catholyte generated higher power than biocatholyte while desalination efficiency when using a biocatholyte was higher than for the chemical catholyte. Power generation at the rate of 1532 mW/m3 and 384 mW/m3 with 41 and 43 % desalination after 24 hours was obtained for the potassium ferricyanide and marine algae catholyte systems respectively. Obtained results suggested that MDCs can be used for partial desalination. Desalination efficiency can be improved by changing the seawater to anolyte ratio and running the system in continuous mode.