Anode Modification as an Alternative Approach to Improve Electricity Generation in Microbial Fuel Cells

Sustainable production of electricity from renewable sources by microorganisms is considered an attractive alternative to energy production from fossil fuels. In recent years, research on microbial fuel cells (MFCs) technology for electricity production has increased. However, there are problems with up-scaling MFCs due to the fairly low power output and high operational costs. One of the approaches to improving energy generation in MFCs is by modifying the existing anode materials to provide more electrochemically active sites and improve the adhesion of microorganisms. The aim of this review is to present the effect of anode modification with carbon compounds, metallic nanomaterials, and polymers and the effect that these modifications have on the structure of the microbiological community inhabiting the anode surface. This review summarizes the advantages and disadvantages of individual materials as well as possibilities for using them for environmentally friendly production of electricity in MFCs

Anode Modification with Reduced Graphene Oxide–Iron Oxide Improves Electricity Generation in Microbial Fuel Cell

In recent years, much research has focused on energy recovery from biomass as an alternative to fossil fuel usage. Microbial fuel cells (MFCs), which produce electricity via microbial decomposition of organic matter, are of great interest. The performance of an MFC depends on the electrode material; most often, carbon materials with good electrical conductivity and durability are used. To increase the power output of an MFC, the anode material can be modified to reduce the internal resistance and increase the anode surface area. Therefore, this study determined how modifying a carbon felt anode with reduced graphene oxide (rGO) and a combination of rGO with iron (III) oxide (rGO-Fe) affected electricity generation in an MFC fueled with wastewater. A mixed microbial consortium was used as the anode biocatalyst. The MFC-rGO-Fe produced significantly higher voltages than other cells (average 109.4 ± 75.1 mV in the cycle). Power density curves indicated that modifying the anode with rGO-Fe increased the power of the MFC to 4.5 mW/m2, 9.3- and 3.9-times higher than that of the control MFC and the MFC-rGO, respectively. Anode modification reduced the internal resistance of the cells from 1029 Ω in the control MFC to 370 and 290 Ω in the MFC-rGO and MFC-rGO-Fe, respectively. These results show that a mixture of rGO with iron (III) oxide positively affects electricity production and can be successfully used for anode modification in the MFCs fueled with wastewater

Biological release of phosphorus is more efficient from activated than from aerobic granular sludge

Abstract Sewage sludge is a rich source of phosphorus. The kinetics of orthophosphate release and the efficiency of phosphorus recovery from aerobic granular sludge (GS) and activated sludge (AS) were compared at external organics (F) to biomass (M) ratios that ranged from 0 to 0.10. Changes in the F/M ratio affected orthophosphates release from AS to a greater extent than their release from GS. On average, increasing the F/M ratio by 0.02 increased the rate of phosphorus release from AS and GS by 2.12 and 1.75 mg P/(L h), respectively. Phosphorus release was highest at an F/M ratio of 0.04 (114.03 and 60.71 mg P/L from AS and GS, respectively). The efficiency of phosphorus recovery from AS ranged from 51.3 to 56.1%; the efficiency of its recovery from GS ranged from 32.8 to 37.5%. From GS, mostly inorganic phosphorus was released (about 8.5 mg/g MLSS), most of which was NAIP, i.e. phosphorus bound to Fe, Mn and Al. At a stoichiometric dose of MgO to PO4 3−, the precipitation efficiency was 30.13% ± 4.51 with uncontrolled pH and reached 81.73% ± 0.17 at a controlled pH of 10

Efficient Manganese Removal in Fast Contact Filters with Continuous Bed Rinsing

There is a need to implement high-efficiency solutions for groundwater treatment, especially in the context of manganese compounds removal. This study analyzed the impact of a water treatment plant modernization to a technology of fast contact filters with continuous bed rinsing. On the basis of basic indicators of water pollution, such as iron, manganese, turbidity, color, and nitrogen compounds, the raw water collected from the groundwater intake and the water treated after the filtration process were characterized. A comparison of the efficiency of water treatment installation before and after modernization indicated that there was a significant improvement in the quality of treated water, especially in terms of manganese removal

Anode Modification with Fe2O3 Affects the Anode Microbiome and Improves Energy Generation in Microbial Fuel Cells Powered by Wastewater

This study investigated how anode electrode modification with iron affects the microbiome and electricity generation of microbial fuel cells (MFCs) fed with municipal wastewater. Doses of 0.0 (control), 0.05, 0.1, 0.2, and 0.4 g Fe2O3 per the total anode electrode area were tested. Fe2O3 doses from 0.05 to 0.2 g improved electricity generation; with a dose of 0.10 g Fe2O3, the cell power was highest (1.39 mW/m2), and the internal resistance was lowest (184.9 Ω). Although acetate was the main source of organics in the municipal wastewater, propionic and valeric acids predominated in the outflows from all MFCs. In addition, Fe-modification stimulated the growth of the extracellular polymer producers Zoogloea sp. and Acidovorax sp., which favored biofilm formation. Electrogenic Geobacter sp. had the highest percent abundance in the anode of the control MFC, which generated the least electricity. However, with 0.05 and 0.10 g Fe2O3 doses, Pseudomonas sp., Oscillochloris sp., and Rhizobium sp. predominated in the anode microbiomes, and with 0.2 and 0.4 g doses, the electrogens Dechloromonas sp. and Desulfobacter sp. predominated. This is the first study to holistically examine how different amounts of Fe on the anode affect electricity generation, the microbiome, and metabolic products in the outflow of MFCs fed with synthetic municipal wastewater

Treatment Efficiency and Characteristics of Biomass in a Full-Scale Wastewater Treatment Plant with Aerobic Granular Sludge

Recently, research are carried out on an implementation of aerobic granular sludge (AGS) technology in full-scale wastewater treatment plants. The aim of the work was to evaluate the effectiveness of organic, phosphorus and nitrogen compounds removal from municipal wastewater and to characterize biomass in a wastewater treatment plant upgraded from activated sludge to AGS technology. In the upgraded facility, granulation was obtained quickly and it was observed that granule morphology depended of the temperature. In the granular biomass harvested at moderate temperatures in the reactor (15°C), the largest share (about 60%) constituted granules with diameters in the range from 125 to 500 μm, while the second-largest biomass fraction constituted granules with diameters over 1 mm (25%). Analysis of granule diameters carried out in winter (temperature in the reactor 8°C) showed a decrease in the share of the largest granules and predominance of granules with diameters in the range from 90 to 355 μm (about 75%). Upgrading municipal wastewater treatment plant from activated sludge to aerobic granular sludge significantly improved the settling properties of the biomass and efficiency of wastewater treatment. The average efficiency of removal of chemical oxygen demand (COD) and phosphorus increased by about 10% and 20%, respectively, while ammonium nitrogen was completely oxidized, regardless of the season. After modernization, the concentration of nitrates in the effluent increased significantly to about 3-6 mg/L. The results of the study show that it is possible to effectively upgrade existing facilities to aerobic granular sludge technology and that this technology is an excellent alternative to a conventional activated sludge

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