Boosting Power Generation by Sediment Microbial Fuel Cell in Oil-Contaminated Sediment Amended with Gasoline/Kerosene

Oil-contaminated sediment amended with chitin enhances power production by minimizing the sediment microbial fuel cell internal resistance

Constructed sediment microbial fuel cell for treatment of fat, oil, grease (FOG) trap effluent: Role of anode and cathode chamber amendment, electrode selection, and scalability

Purpose The independent incorporation of biochar and sediment microbial fuel cells (SMFCs) into paddy soil has been shown to reduce methane (CH4) emissions. However, the application of rice straw into paddy soil enhances the availability of labile carbon that stimulates methanogen growth, counteracting the mitigation effects of both methods. This study, therefore, aimed to investigate the effect of coupling biochar and SMFC on CH4 and CO2 emissions from straw-amended paddy soil. Materials and methods Single chamber SMFC setups constructed using acrylic columns (height, 25 cm; inner diameter, 9 cm) with six treatments were established using soil amended with 0% (0BC), 1% (1BC), and 2% (2BC) biochar: with and without SMFC conditions. Stainless steel mesh (15 × 3 cm) and graphite felt (6 × 5 cm) were used as anode and cathode materials, respectively. Results Cumulative emission of CH4 in the 0BC treatment with SMFC was 39% less than in that without SMFC. Biochar addition and SMFC operation together further reduced CH4 emission by 57% and 60% in 1BC and 2BC treatments, respectively, compared to that in the 0BC treatment without SMFC operation. The relative abundance of microbial communities indicated methane-oxidizing bacteria were enriched in the presence of biochar and hydrogenotrophic Methanoregula were suppressed by SMFC operation. This suggested that SMFC mainly inhibited CH4 production by outcompeting hydrogenotrophic archaea. Conclusion The use of biochar made from leftover rice straw has an interactive effect on SMFC operation and both methods can be used to reduce CH4 emission from straw-amended paddy soil.

An emerging technology that could be utilized for ocean energy production is the microbial fuel cell. Microbial fuel cells are able to oxidize biodegradable fuels, such as organic waste, to generate electrical power. The sediment microbial fuel cell (SMFC) is a specialized subset of microbial fuel cells relevant in generating energy in the ocean environment. SMFCs are devices which are able to directly produce electrical energy by bacteria consuming biodegradable compounds in marine sediments. In sediments with low organic carbon, SMFCs have only been observed to provide relatively low amounts of power. Therefore, one hypothesis was to evaluate power production in a SMFC post an addition of an external carbon source. However, because this is in a seawater system, the carbon source should be in a solid phase. Types of solid amendments can include simple plant materials (lignin/cellulose) or animal by-products (chitin, deceased organisms, or other waste products). In this study, chitin from shrimp shell waste was used as a method of increasing organic carbon to increase or prolong power production and for SMFC operation in sandy, low carbon sediments. SMFC's were tested in two San Diego Bay sediment types; low total organic carbon (TOC) and average TOC: 0.2% TOC and 2.5% TOC, respectively. SMFC units with chitin wrapped in water soluble tape were evaluated under static sea water conditions, as well as in the field. Results for chitin from shrimp shell waste indicated that power density was greater by a factor of 2 relative to control units in sediments with 2.5% TOC; and in sediments with low TOC, 0.2%, power output is 100 times greater. Therefore, these data in both normal and low organic carbon sediments demonstrate that chitin enhances and lengthens power production.

Sediment microbial fuel cell (SMFC) is a bio-electrochemical device which generates green electricity from microbes. SMFC are projected to be employed as a sustainable power source for led lighting and remote environmental observing. To understand the performance of SMFC, experiment performs for one month. Single SMFC has low voltage and current level which is unable to drive electronic devices. To increase power generation from SMFC, eight individual SMFC are connected together either in series or in hybrid connection. Two combinations of this SMFC, hybrid connection, are proving to be the more effective one, step-up both the voltage and current level, mutually. Polarization curve and behavior of voltage generation experiments are done for series and hybrid connected SMFC. The power density is obtained 1.111mW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 435.25 μ A from series and 1.309mW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 870.75μ A in hybrid connected SMFC. This study suggests that maximized the power production of SMFC by connecting series and hybrid for practical use of the device.

To prevent the occurrence of black water agglomerate through delaying decomposition of cyanobacterial bloom biomass by sediment microbial fuel cell

Anaerobic biodegradation of petroleum-contaminated sediments can be accomplished by a sediment microbial fuel cell (SMFC), but the recovered energy is very low (~4 mW m−2). This is due to a high internal resistance (Ri) that develops in the SMFC. The evaluation of the main experimental parameters that contribute to Ri is essential for developing a feasible SMFC design and this task is normally performed by electrochemical impedance spectroscopy (EIS). A faster and easier alternative procedure to EIS is to fit the SMFC polarization curve to an electrochemical model. From there, the main resistance contributions to Ri are partitioned. This enables the development of a useful procedure for attaining a low SMFC Ri while improving its power output. In this study, the carbon-anode surface was increased, the biodegradation activity of the indigenous populations was improved (by the biostimulation method, i.e., the addition of kerosene), the oxygen reduction reaction was catalyzed, and a 0.8 M Na2SO4 solution was used as a catholyte at pH 2. As a result, the initial SMFC Ri was minimized 20 times, and its power output was boosted 47 times. For a given microbial fuel cell (MFC), the main resistance contributions to Ri, evaluated by the electrochemical model, were compared with their corresponding experimental results obtained by the EIS technique. Such a validation is also discussed herein.

Sediment microbial fuel cells (SMFCs) have been used as renewable power sources for sensors in fresh and ocean waters. Organic compounds at the anode drive anodic reactions, while oxygen drives cathodic reactions. An understanding of oxygen reduction kinetics and the factors that determine graphite cathode performance is needed to predict cathodic current and potential losses, and eventually to estimate the power production of SMFCs. Our goals were to (1) experimentally quantify the dependence of oxygen reduction kinetics on temperature, electrode potential, and dissolved oxygen concentration for the graphite cathodes of SMFCs and (2) develop a mechanistic model. To accomplish this, we monitored current on polarized cathodes in river and ocean SMFCs. We found that (1) after oxygen reduction is initiated, the current density is linearly dependent on polarization potential for both SMFC types; (2) current density magnitude increases linearly with temperature in river SMFCs but remains constant with temperature in ocean SMFCs; (3) the standard heterogeneous rate constant controls the current density temperature dependence; (4) river and ocean SMFC graphite cathodes have large potential losses, estimated by the model to be 470 mV and 614 mV, respectively; and (5) the electrochemical potential available at the cathode is the primary factor controlling reduction kinetic rates. The mechanistic model based on thermodynamic and electrochemical principles successfully fit and predicted the data. The data, experimental system, and model can be used in future studies to guide SMFC design and deployment, assess SMFC current production, test cathode material performance, and predict cathode contamination.

Sediment microbial fuel cells (SMFCs) are different from microbial fuel cells because they are completely anoxic and lack a membrane. SMFCs are a novel technology for the simultaneous production of renewable energy and bioremediation of heavy metals. Recently, SMFCs have attracted the attention of many researchers because of their moderate functioning parameters and ability to use a range of biodegradable substrates like glucose, glutamic acid, river water, cysteine, acetate, and starch. The inocula used in SMFCs include river sediment, marine sediment, and wastewater. For power generation, many exoelectrogens in SMFCs have the ability to transfer electrons from electrodes by using natural electron shuttles. Exoelectrogens use four primary pathways to transfer electrons to the electrodes, including short-range electron transfer through redox-active proteins, soluble electron shuttling molecules, long-range electron transport by conductive pili, and direct interspecies electron transfer. The most dominant mechanism is long-range electron transfer via conductive pili because pili have metal-like conductivity. The powering by microbes is an emerging technique for the remediation of heavy metals from sediments. The pathways for transferring electrons in electrotrophs operate in the opposite direction from those in exoelectrogens. To further upgrade SMFC technology, this review targets the prototype, operating factors, working mechanisms, applications, and future perspectives of SMFCs. Copyright © 2017 John Wiley & Sons, Ltd.

Sediments play an important role in determining the quality of lakes, rivers and oceans as they can act as either a source or sink for pollutants. Once the input pollution is controlled, sediments as a secondary source of pollution can release the accumulated pollutants to overlying water.1 The organic matter content of sediments can also affect the structure of macroinvertebrate assemblages.2 To date, traditional sediments remediation methods include monitored natural recovery, in-situ treatment, and ex-situ treatment.3 The traditional methods are either expensive or not environmentally friendly, so it is crucial to find a cost-effective and environmentally friendly way to solve the contaminated sediments problem. Microbial fuel cell (MFC) technology is considered an environmentally friendly and promising approach for converting wastewater or solid waste into electricity.4–6 Recently, some studies have shown that sediment microbial fuel cell (SMFC) can alter the properties and enhance the removal of organic matter in sediment.7–9 Wang9 developed a three-dimensional floating biocathode to dispose river sediments, and concluded that the sediment organic matter content near the anode was removed by 29 %. Hong7 found that sediment organic matter around the electrodes became more humified, aromatic, and polydispersed, and had a higher average molecular weight, along with its partial degradation and electricity generation compared to that of the original sediment. Sajana10 studied the performance of SMFC by adding cellulose in freshwater and demonstrated effective cellulose degradation from aquaculture pond sediment and maintained the oxidized sediment top layer favourable for aquaculture. Zhou11 improved the SMFC performance by amendment of colloidal iron oxyhydroxide into sediments and concluded that high Fe(II) concentration in pore water of sediments led to high power production. Song12 found that the addition of biomass in appropriate proportions can enhance output power in SMFC. However, mass transfer limitations for electron donors to reach the anode and a low rate of oxygen reduction in cathodes were major limitations for power production.13 In freshwater environments, the maximum power densities in SMFC with felt graphite14 and carbon paper15 as cathode were 4 mW m–2 and 2 mW m–2 respectively. Song13 constructed SMFC with granule activated carbon cathode and stainless steel anode and obtained 3.5 mW m–2 maximum power density, and further increased to 11.2 mW m–2 by adding cellulose. Jiang16 built MFC with graphite fiber brush and enhanced TCOD removal rate from 11.3 % to 19.2 % for raw sludge. Removal and Changes of Sediment Organic Matter and Electricity Generation by Sediment Microbial Fuel Cells and Amorphous Ferric Hydroxide

Sediment microbial fuel cells (SMFCs) generate bioelectricity from benthic sediments and thus providing both bioelectricity generation and sediment remediation. However, the high internal resistance of the cathode leads to a low power output, which requires research on cathode treatment. In this study, we explored the influence of light irradiation on bioelectricity production and nutrient removal in the SMFC system. The microcosm experiment of the SMFC system was designed with artificial illumination of 500 lux (light-SMFC) and compared with dark conditions of 15 lux (dark-SMFC), which showed that the current increases during photoperiods. The study reveals that light-illuminated SMFC consistently produced the highest voltage, with the highest voltage (553 mV) being 1.3 times higher than the dark-SMFC (440 mV). The polarization curves show a significant reduction in internal cathodic resistance under light condition, resulting in increased voltage generation. The light-SMFC exhibits the highest maximum power density of 35.93 mW/m2, surpassing the dark SMFC of 31.13 mW/m2. It was found that light illumination in the SMFC system increases oxygen availability in the cathodic region, which supports the oxygen reduction reaction (ORR) process. At the same time, the high bioelectricity output contributes to the highest sediment remediation by greatly reducing the chemical oxygen demand (COD) and phosphate (PO4–P) concentrations. The study highlights the potential of light illumination in mitigating cathodic limitation to improve SMFC performance and nutrient removal.

Microbial fuel cell improves restoration of Hydrilla verticillata in an algae-rich sediment microcosm system

Free-Radical Redox Timer and Antioxidant Therapy of Aging: From Chemistry of Free Radicals to Systems Theory of Reliability

Organic carbon compounds removal and phosphate immobilization for internal pollution control: Sediment microbial fuel cells, a prospect technology

Evaluation of low-cost carbon/metal electrodes as cathodes and anodes in sediment microbial fuel cells