Journal of Energy Bioscience 2024, Vol.15, No.3, 186-196 http://bioscipublisher.com/index.php/jeb 192 6.3 Energy recovery results and efficiency analysis The MFC system demonstrated impressive results in terms of both wastewater treatment and energy recovery. At an HRT of 16 hours, the system achieved a power density of (225±1.4) mW/m² and a substrate degradation rate of (84.4±0.8)%, including a (95±0.6)% reduction in oil content. The columbic efficiency was recorded at (2±0.8)%, with a projected power yield of (340±20) kWh/kg CODR/day. These results indicate that the MFC system not only effectively treated the refinery wastewater but also generated a significant amount of electricity, making it a viable option for energy recovery (Abbasi et al., 2016). 6.4 Comparison with traditional wastewater treatment methods Traditional wastewater treatment methods, such as activated sludge processes and trickling filters, are energy-intensive and often require constant aeration and sludge management. In contrast, MFCs offer a sustainable alternative by enabling simultaneous wastewater treatment and energy recovery. The MFC system in this study achieved higher COD removal efficiencies and lower energy consumption compared to conventional methods. For instance, the MFC-MBR integrated system showed a 96.3% COD removal efficiency and a 50% reduction in transmembrane pressure, highlighting its superior performance and lower operational costs (Kumar et al., 2019; Munoz-Cupa et al., 2021). 7 Economic and Environmental Benefits 7.1 Cost analysis of implementing MFCs in wastewater treatment plants The implementation of microbial fuel cells (MFCs) in wastewater treatment plants presents a promising avenue for cost reduction and energy recovery. Studies have shown that integrating MFCs with existing treatment processes can significantly reduce operational costs by generating electricity from organic waste, which can offset the energy requirements of the treatment process. For instance, a study on a hybrid MFC-MBR system demonstrated that the energy recovered from the MFC could be used to power the membrane bioreactor, thereby reducing the overall energy consumption of the system (Wang et al., 2016). Additionally, the use of low-cost materials in the construction of MFCs, such as non-platinum catalysts, further enhances their economic feasibility (Zhuang et al., 2012). The potential for cost savings is also evident in the reduced need for aeration and sludge management, which are major cost drivers in conventional aerobic treatment processes. 7.2 Environmental impact: reduction in greenhouse gas emissions and energy savings The environmental benefits of MFCs are substantial, particularly in terms of reducing greenhouse gas emissions and achieving energy savings. MFCs offer a dual advantage of treating wastewater while simultaneously generating electricity, which can be used to power the treatment process or other applications. This reduces the reliance on external energy sources, thereby lowering the carbon footprint of wastewater treatment plants. For example, the integration of MFCs with anaerobic treatment processes has been shown to enhance energy recovery and reduce the overall energy consumption of the system (Ardakani and Gholikandi, 2020). Furthermore, MFCs can significantly reduce the emission of greenhouse gases by minimizing the need for energy-intensive aeration processes and by capturing methane produced during anaerobic digestion (Rahman et al., 2017; Kumar et al., 2019). The use of MFCs in treating industrial wastewater also helps in the removal of pollutants such as nitrogen and phosphorus, which can otherwise contribute to environmental degradation. 7.3 Long-term sustainability and scalability of MFC applications The long-term sustainability and scalability of MFC applications in wastewater treatment are promising, although challenges remain. The scalability of MFCs has been demonstrated in various studies, with systems being able to treat real wastewater continuously and efficiently (Zhuang et al., 2012). The integration of MFCs with other treatment processes, such as membrane bioreactors and anaerobic digestion, has shown to improve treatment efficiency and energy recovery, making the system more sustainable in the long run (Ardakani et al., 2020). However, issues such as low power density and high initial investment costs need to be addressed to make MFCs commercially viable on a larger scale. Advances in materials science and engineering, as well as a better understanding of microbial communities, are expected to enhance the performance and reduce the costs of MFCs,
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