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Summary: Bioaugmentation is considered a potential tool to boost the performance of microbial fuel cells (MFCs) by modifying electrodes with biopolymers. However, research on biopolymers in MFCs to treat real wastewater is very limited. Polylactic acid (PLA) is a biopolymer obtained from renewable feedstock, extensively being used in the form of nanofibers due to its biocompatible nature, while polyaniline (PANI) is a favorite candidate for electrode modification in MFC under its good electrical conductivity and stability. Interestingly, PANI‐based degradable nanofibers are known to support cell adhesion and proliferation. The current work is, therefore, aimed at finding a new environmentally benign composite material using electrospun PLA nanofiber decorated with in situ polymerized PANI. The resultant PANI/PLA electrode was tested for its efficacy as anode with domestic wastewater‐fed MFCs against conventional graphite felt. The flexible anode outperformed the flat graphite felt anode displaying a 92.32% decrement in charge transfer impedance and 8‐fold increase in maximum power density with excellent cell adherence under which simultaneous COD removal of 91.7% was also achieved. The present study has successfully added a new dimension to the design of sustainable anode material to enhance microbial binding and achieve high power output, revealing the enormous potential of biopolymer‐based MFCs in the future. By switching to the biopolymer flexible electrode that rivals its traditional polymers, the MFCs demonstrate promise to be a vital tool accessible in the remotest part of the world lacking electrical infrastructure for simultaneous clean water and electricity generation. Highlights: 8‐fold increase in power density in real wastewater‐fed MFCs using novel PANI/PLA anode.91.7% COD removal from domestic wastewater using mediator‐less MFCs.Pseudocapacitive nature displayed by the biopolymer‐based anode.Enhanced bio‐synergistic interaction between wastewater‐borne microbial biofilm and bioaugmented anode. [ABSTRACT FROM AUTHOR]

Summary: Microbial fuel cells (MFCs) are considered as power generation devices for sustainable energy. However, the power generated is insignificant compared to other energy production devices. In this study, a mini autonomous biosensor (MAB) based on MFCs has been designed for detecting hazardous hexavalent chromium in wastewater. Hexavalent chromium has been classified as a human carcinogen causing serious birth defects due to its mutagenic and teratogenic properties. The power generated by the MAB has been investigated to study the feasibility of providing power to itself. In addition, electrochemical analyses of conductive silver paste and carbon cloth as the anode were conducted in the MAB for detecting hexavalent chromium in the anode chamber. Results show that a maximum voltage of 518.17 mV and a power density of 1.075 mW/cm2 could be achieved using carbon cloth with an external resistance of 1000 Ω, while a higher limiting current density of 0.015 mA/cm2 could be achieved with conductive silver glue as the anode electrode. Besides, the voltage output of the MAB decreased rapidly with the addition of hexavalent chromium into the wastewater. Also, the recovery time for the MAB was much shorter than found in previous studies. The MAB demonstrated potential for simultaneous production of electricity and detection of hexavalent chromium, which would open up avenues for autosensing applications in the environment as well as smart powering devices. Results indicate that the MAB with conductive silver glue as anode electrode is feasible for detecting hexavalent chromium in wastewater. [ABSTRACT FROM AUTHOR]

Summary: Microbial fuel cells (MFCs) are bioelectrochemical transducers that can be used to produce electrical power under the activity of microbes during the wastewater treatment processes. In the present study, the electrode spacing was considered as a parameter to investigate the influence on the performance of MFCs. The electrode spacing was defined as the distance of the anode electrode plate to the polymer exchange membrane in the MFCs. Three values were set at 0.0, 3.0, and 6.0 cm, respectively. In addition, a flow device, like a honeycomb type flow straightener, was introduced and implemented in the anode chamber for creating a uniform flow. The inner diameter of the honeycomb was 0.7 cm. Results showed that a higher limiting current density with 4108.7 mA/m2 and a lower resistance with 2.51 Ω can be found in the case of the 0.0 cm electrode spacing. These results also indicated that the shorter electrode spacing with flow straightener devices would improve the performance of MFCs, leading to lower internal resistance and higher power density. In addition, the scanning electron microscopy was employed to analyze the biofilm thickness for MFCs with different electrode spacing. It was also found that the biofilm thickness with 0 cm electrode spacing was larger than the other two cases, leading to a lower internal resistance in the MFCs. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) have become a promising approach to generate cleaner and more sustainable electrical energy. Involvement of various disciplines had been contributing to enhance the performance of the MFCs. Factors affecting the performance such as chemical components, bacteria species, electrodes materials, flow interaction and electrical parts are being widely reviewed, however most of the research are highly field-specific without considering other important variables from different disciplines. In this study, Buckingham's Pi Theorem has been utilized to be implemented in the design pattern of MFCs. Several dominated variables of interest have also been pointed out including the design limitation. Modelling and application of Buckingham's Pi Theorem has been discussed as well which is useful for performance enhancement of MFCs and their application in wastewater treatment in the future. • Buckingham's Pi Theorem combines all dimensional variables to give dimensionless variables. • Buckingham's Pi Theorem reduces experiment time and cost by decreasing experiment repetition. • Interrelation of parameters in microbial fuel cell design and design limitation. [ABSTRACT FROM AUTHOR]