Evaluating the performance of coupled MFC-MEC with graphite felt/MWCNTs polyscale electrode in landfill leachate treatment, and bioelectricity and biogas production

Synchronously degradation of biogas slurry and decarbonization of biogas using microbial fuel cells

Two-chamber microbial fuel cell (MFC) with biogas slurry (BS) of corn stover as the anode substrate and Chlorella as the cathode substrate was investigated to solve the problem of the accumulation of wastewater generated from biogas plants and to achieve low-cost separation of CO2 from biogas. A simple two-compartment MFC was constructed using biocatalysis and inexpensive materials without expensive catalysts. The performance of MFC (X1-W, Y1-W, Z1-W) with different biogas solution concentrations as anode substrate and MFC (X2-C, Y2-C, Z2-C) with Chlorella as biocathode were compared, respectively. The MFCs (Z1-W,) can start quickly and maintain a stable power production (286.82 mV ± 184.59 mV). The growth rate of Chlorella at the MFCs (X2-C, Y2-C, Z2-C) biocathode was highly coincident with the output voltage. The MFC (Z2-C) has a maximum power density of 489.7 mW/m2 when the external resistance is varied to 200 Ω. The removal rates of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) are 93.42% and 92.59%. The maximum cell growth (Xmax) of Chlorella was 125.61 mg d-1, biomass productivity (Pmax) was 95.60 g L-1 d-1 and the maximum CO2 biofixation rate (RCO2) was 175.26 mg L-1 d-1. The microbial community analysis showed that the microorganisms in the anode solution were mainly from the biogas slurry and belonged to the hydrolytic bacteria. At the same time, the electroactive microbial community was mainly from anaerobic sludge. Therefore, MFCs can effectively degrade the organic matter in the biogas solution and generate electricity, and use Chlorella to absorb CO2 from the biogas, providing a new method for the development of biogas industry.

Nano-pumice derived from pumice mine waste as a low-cost electrode catalyst for microbial fuel cell treating edible vegetable oil refinery wastewater for bioenergy generation and reuse

This study aimed to assess nano-pumice (NP) from pumice mining waste as a local, cost-effective anode catalyst in microbial fuel cells (MFCs) for treating edible vegetable oil refinery wastewater (EVORW) and generating bioenergy. Pumice mining waste was converted into nano in three stages: crushing up to ≤3 cm, reducing the size of the previous step particles to 150 μm and converting the previous step particles to <100 nm. Nano-pumice prepared was coated on the carbon cloth (CC) to increase anode surface area of MFC. Two MFCs were utilized, with MFC-1 serving as a control and MFC-2 incorporating a CC electrode coated with nano-pumice. The surface morphology, elemental and chemical composition, and textural characterization of CC, pumice, NP, and CC coated with NP were analyzed using FE-SEM, EDX, XRF, and BET techniques. MFC-2 achieved a maximum power density of 30±4W/m³ at a current density of 55±5A/m³. The MFC-1 reached a maximum power density of 18±4W/m³ at a current density of 35±6A/m³. In MFC-2, the EVORW treatment achieved maximum removals of COD (94 ± 2 %), NH4 +-N (85 ± 4 %), TP (76 ± 5 %), SO4 2- (68 ± 6 %), TSS (81 ± 2 %), and TDS (73 ± 1 %). MFC-1 achieved removal efficiencies of 66 ± 3 % for COD, 57 ± 6 % for NH4 +-N, 48 ± 3 % for TP, 45 ± 3 % for SO4 2-, 65 ± 3 % for TSS, and 61 ± 1 % for TDS. MFC-2 power density rose significantly, reaching 61 ± 3 % (1.6 times) higher than MFC-1and it also demonstrated a superior ability to improve raw wastewater quality compared to MFC-1. The MFC with the CC/NP anode exhibited both excellent power production and high COD removal efficiency, making nano-pumice a suitable anode catalyst for MFC applications.

Utilization of microbial fuel cells as a dual approach for landfill leachate treatment and power production: a review

Landfill leachate, which is a complicated organic sewage water, presents substantial dangers to human health and the environment if not properly handled. Electrochemical technology has arisen as a promising strategy for effectively mitigating contaminants in landfill leachate. In this comprehensive review, we explore various theoretical and practical aspects of methods for treating landfill leachate. This exploration includes examining their performance, mechanisms, applications, associated challenges, existing issues, and potential strategies for enhancement, particularly in terms of cost-effectiveness. In addition, this critique provides a comparative investigation between these treatment approaches and the utilization of diverse kinds of microbial fuel cells (MFCs) in terms of their effectiveness in treating landfill leachate and generating power. The examination of these technologies also extends to their use in diverse global contexts, providing insights into operational parameters and regional variations. This extensive assessment serves the primary goal of assisting researchers in understanding the optimal methods for treating landfill leachate and comparing them to different types of MFCs. It offers a valuable resource for the large-scale design and implementation of processes that ensure both the safe treatment of landfill leachate and the generation of electricity. The review not only provides an overview of the current state of landfill leachate treatment but also identifies key challenges and sets the stage for future research directions, ultimately contributing to more sustainable and effective solutions in the management of this critical environmental issue.

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.

Effective salt removal from domestic reverse osmosis reject water in a microbial desalination cell

Microbial desalination cells (MDC) are evaluated as an environmentally friendly approach for purifying saline water by using power generated by the decomposition of organic materials in the wastewater. The present study is to evaluate the ferrocyanide-redox and biocathode approach in treating simulated saline water and subsequently recovering bio-electricity using actual domestic reverse osmosis reject water. For the desalination of simulated saline water and domestic reverse osmosis reject water, a three-chamber microbial desalination cell with graphite electrodes and anion and cation exchange membranes was constructed. When treating simulated saline water, the biocathode technique achieved a 5% improvement in salt removal and a 4.9% increase in current and power density when compared to the ferrocyanide-redox approach. When biocathode MDC was used to treat domestic reverse osmosis reject water, a maximum current and power density of 3.81 μA/cm² and 0.337 μW/cm², respectively, were recorded, as well as COD removal of 83.9% at the desalination chamber and ions reduction for Na, K, and Ca of up to 79%, 76.5%, and 72%, respectively, in a batch operation for 31 days with a stable pH (≈ 7). Thus, the study revealed a microbial desalination cell capable of recovering bioenergy and reducing salt from domestic reverse osmosis reject water with a consistent pH range.

Advanced bioelectrochemical system for nitrogen removal in wastewater

Nitrogen (N) pollution in water has become a serious issue that cannot be ignored due to the harm posed by excessive nitrogen to environmental safety and human health; as such, N concentrations in water are strictly limited. The bioelectrochemical system (BES) is a new method to remove excessive N from water, and has attracted considerable attention. Compared with other methods, it is highly efficient and has low energy consumption. However, the BES has not been applied for N removal in practice due to lack of in-depth research on the mechanism and construction of high-performance electrodes, separators, and reactor configurations; this highlights a need to review and examine the efforts in this field. This paper provides a comprehensive review on the current BES research for N removal focusing on the reaction principles, reactor configurations, electrodes and separators, and treatment of actual wastewater; the corresponding performances in these realms are also discussed. Finally, the prospects for N removal in water using the BES are presented.