Energy advantage of anode electrode rotation over anolyte recirculation for operating a tubular microbial fuel cell

Microbial fuel cell in long-term operation and providing electricity for intermittent aeration to remove contaminants from sewage

Microbial fuel cells (MFCs) show promise in sewage treatment because they can directly convert organic matter (OM) into electricity. This study aimed to demonstrate MFCs stability over 750 days of operation and efficient removal of OM and nitrogenous compounds from sewage. To enhance contaminant removal, oxygen was provided into the anode chamber via a mini air pump. This pump was powered by the MFCs' output voltage, which was boosted using a DC-DC converter. The experimental system consisted of 12 sets of cylindrical MFCs within a 246L-scale reactor. The boosted voltage reached 4.7 V. This voltage was first collected in capacitors every 5 min and then dispensed intermittently to the air pump for the MFCs reactor in 4 s. This corresponds to receiving average DO concentration reaching 0.34 ± 0.44 mg/L at 10 cm above the air-stone. Consequently, the degradation rate constants (k) for chemical oxygen demand (COD) and biological oxygen demand (BOD) in the presence of oxygen were 0.048 and 0.069, respectively, which surpassed those without oxygen by 0.039 and 0.044, respectively. Aeration also marginally improved the removal of ammonia because of its potential to create a favorable environment for the growth of anammox and ammonia-oxidizing bacteria such as Candidatus brocadia and Nitrospira. The findings of this study offer in-depth insight into the benefits of boosted voltage in MFCs, highlighting its potential to enhance contaminant degradation. This serves as a foundation for future research focused on improving MFCs performance, particularly for the removal of contaminants from wastewater.

Embedded Graphite and Carbon Nanofibers in a Polyurethane Matrix Used as Anodes in Microbial Fuel Cells for Wastewater Treatment

Composites of polyurethane and graphite and polyurethane and carbon nanofibers (PU/Graphite 0.5% and PU/CNF 1%) were synthesized and used as anodes in dual-compartment microbial fuel cells (MFCs) for municipal wastewater treatment; electrical energy generation and organic matter removal were assessed. The maximum power density, coulombic efficiency and chemical oxygen demand (COD) removal efficiency in the MFCs packed with the PU/Graphite 0.5% and PU/CNF 1% composites were 232.32 mW/m3 and 90.78 mW/m3, 5.87 and 4.41%, and 51.38 and 68.62%, respectively. In addition, the internal resistance of the MFCs with the best bioelectrochemical performance (PU/Graphite 0.5%) was 1051.11 Ω. The results obtained in this study demonstrate the feasibility of using these types of materials in dual-compartment MFCs for wastewater treatment with electric power generation.

Industrial bioelectrochemistry for waste valorization: State of the art and challenges

Bioelectrochemistry has gained importance in recent years for some of its applications on waste valorization, such as wastewater treatment and carbon dioxide conversion, among others. The aim of this review is to provide an updated overview of the applications of bioelectrochemical systems (BESs) for waste valorization in the industry, identifying current limitations and future perspectives of this technology. BESs are classified according to biorefinery concepts into three different categories: (i) waste to power, (ii) waste to fuel and (iii) waste to chemicals. The main issues related to the scalability of bioelectrochemical systems are discussed, such as electrode construction, the addition of redox mediators and the design parameters of the cells. Among the existing BESs, microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) stand out as the more advanced technologies in terms of implementation and R&D investment. However, there has been little transfer of such achievements to enzymatic electrochemical systems. It is necessary that enzymatic systems learn from the knowledge reached with MFC and MEC to accelerate their development to achieve competitiveness in the short term.

Microbial fuel cells for bioelectricity production from waste as sustainable prospect of future energy sector

Microbial fuel cell (MFC) is lauded for its potentials to solve both energy crisis and environmental pollution. Technologically, it offers the capability to harness electricity from the chemical energy stored in the organic substrate with no intermediate steps, thereby minimizes the entropic loss due to the inter-conversion of energy. The sciences underneath such MFCs include the electron and proton generation from the metabolic decomposition of the substrate by microbes at the anode, followed by the shuttling of these charges to cathode for electricity generation. While its promising prospects were mutually evinced in the past investigations, the upscaling of MFC in sustaining global energy demands and waste treatments is yet to be put into practice. In this context, the current review summarizes the important knowledge and applications of MFCs, concurrently identifies the technological bottlenecks that restricted its vast implementation. In addition, economic analysis was also performed to provide multiangle perspectives to readers. Succinctly, MFCs are mainly hindered by the slow metabolic kinetics, sluggish transfer of charged particles, and low economic competitiveness when compared to conventional technologies. From these hindering factors, insightful strategies for improved practicality of MFCs were formulated, with potential future research direction being identified too. With proper planning, we are delighted to see the industrialization of MFCs in the near future, which would benefit the entire human race with cleaner energy and the environment.

Effects of Modified Anodes on the Performance and Microbial Community of Microbial Fuel Cells Using Swine Wastewater

Microbial fuel cells (MFCs) have emerged as a sustainable technology for wastewater treatment that has potential to recycle bioelectricity from livestock wastewater. The performance of MFCs is influenced by the synergistic effect of anode material with nearby microorganisms. In this study, three identical double-chambered MFCs with different anode carbon clothes using swine wastewater are established. The optimization mechanism of MFC performance is analyzed by anode characteristics, cell performance, and microbial community, respectively. The results show that the surface structure and properties of the anode carbon cloth can be obviously improved by the acid–heat-modified treatment. The community structure of anodic biofilm, which varied with different modification methods, was mainly dominated by Proteobacteria, Firmicutes, and Bacteroidetes. These findings demonstrate efficient and simple methods for improving the performance of MFCs based on swine wastewater and may help to explore the influence mechanism of different modified anodes on the exoelectrogens.