The simultaneous treatment of wastewater and generation of electricity using single-chamber, two-chamber, and stacked-cell microbial fuel cell configurations are well-documented in the literature. Recently, several studies have demonstrated the possibility of integrating microbial fuel cells into existing wastewater treatment configurations (e.g. sequencing batch reactors and membrane systems) for simultaneous removal of carbonaceous and nitrogenous pollutants and electricity production from wastewater. Rotating biological contactors are important biofilm processes used for organic carbon removal and nitrification that microbial fuel cells could be integrated into. The objective of this study was to test the possibility of integrating microbial fuel cells into rotating biological contactor systems for COD removal and nitrification and electricity generation from wastewater. To achieve this objective, two three-stage rotating biological contactor units (RBC and RBC-MFC) were constructed. The RBC-MFC was operated in a closed-circuit mode while the RBC was used as a control (open circuit). The anode was made of carbon fiber brush that extended along the bottom of each stage. Each stage had a horizontal graphite shaft on which eight carbon felt cathode discs were mounted. Six experimental runs were conducted to test the effect of the hydraulic loading rate, COD/N ratio and step-feeding conditions on organic carbon and ammonia removal on both units. Although the system needs to be optimized to generate higher voltage outputs and current densities, this study showed the possibility of integrating microbial fuel cells into rotating biological contactor systems with efficient removal of both COD and ammonia.

Current wastewater treatment technologies are not sustainable simply due to their high operational costs and process inefficiency. Integrated Microbial Fuel Cells for Wastewater Treatment is intended for professionals who are searching for an innovative method to improve the efficiencies of wastewater treatment processes by exploiting the potential of Microbial Fuel Cells (MFCs) technology. The book is broadly divided into four sections. It begins with an overview of the "state of the art" bioelectrochemical systems (BESs) as well as the fundamentals of MFC technology and its potential to enhance wastewater treatment efficiencies and reduce electricity generation cost. In section two, discusses the integration, installation, and optimization of MFC into conventional wastewater treatment processes such as activated sludge process, lagoons, constructed wetlands, and membrane bioreactors. Section three outlines integrations of MFCs into other wastewater processes. The final section provides explorative studies of MFC integrated systems for large scale wastewater treatment and the challenges which are inherent in the upscaling process. Clearly describes the latest techniques for integrating MFC into traditional wastewater treatment processes such as activated sludge process, lagoons, constructed wetlands, and membrane bioreactors Discusses the fundamentals of bioelectrochemical systems for degrading the contaminants from the municipal and industrial wastewater Covers methods for the optimization of integrated systems

A hybrid system was developed by integrating MFC into CW for enhanced wastewater treatment and bioelectricity generation. The research is divided into five major scopes. The first scope is about design and fabrication of CW-MFC reactor, where electrodes are embedded into CW and feasibility of such hybrid system was tested for simultaneous organic and nutrient-containing wastewater treatment and bioelectricity production. Evaluation on denitrification, nitrification and organic matter removal efficiency corroborate wastewater treatment capabilities, and bioelectricity production performance were carried out. The performance of CW-MFC was compared with previous literature on CW reactor of similar dimension, design and configuration to corroborate the effectiveness of the hybrid system. The second scope of the research mainly focuses on the investigation of the effect of electrode spacing, the effect of organic loading rates, the effect of circuit connection on the performance of organic pollutant removal and electricity generation. The overall performance between the closed circuit and open circuit system were compared and put into perspective. The morphology of granular activated carbon electrodes was observed by using a scanning electron microscope (SEM).

Microbial fuel cells (MFCs) are electrochemical devices that use metabolic activities of microorganisms to oxidize organic and inorganic matter and generate electricity. MFC technology is a multidisciplinary approach to the quest for alternate sources of energy. In recent years, MFC technology expressed itself as potential technology for simultaneous electricity generation and waste treatment. It is the purpose of this book to outline, in a concise but comprehensible manner, the fundamentals and development of MFCs and their application as wastewater treatment device. This Book comprises six parts: Chapter 1 contains Introduction and aim of present work. Chapter 2 deals with the critical analysis of MFC research in past and future possibilities. Chapter 3 discloses major methodology used, while Chapter 4 shows the detailed results. Chapter 5 contains conclusion and Chapter 6 is conclusion of present research. As this book is based on results of MFC research, in writing it, the author has drawn about all aspects of MFCs to understand MFCs from every point of view. This book will be beneficial for students, researchers and teachers working on wastewater treatment and bioelectricity.

Microbial fuel cells (MFCs) are bioelectrochemical devices that allow the harvesting of electricity generated during anaerobic respiration of selected bacterial species. This technology shows promise in both wastewater treatment and sustainable bioenergy conversion applications. Bacterial respiration occurs in the anaerobic anode compartment of the MFC, and is electrochemically coupled with electron acceptors in the MFC's aerobic cathode compartment. This dissertation addresses a variety of MFC applications and includes a comprehensive summary of the published results of bacterio-algal MFCs. This review summarizes not only successful published results of bacterio-algal fuel cells but also highlights critical operational parameters and their effect on power generation and output efficiency. Power generation and desalination performance of microbial desalination cells (MDCs) were compared using two different catholytes; (1) Nanochloropsis salina, a marine algae and (2) potassium ferricyanide in chapter three. Anodic biofilms and current generation during biofilm growth were examined using single chambered MFCs submersed in algal catholyte. As part of the dissertation research study, we conducted experiments to explore the role of graphite anodes in the decolorization of Reactive Black 5 (RB5) azo dye and Reactive Blue 4 (RBL4) anthraquinone dye coupled with voltage generation in MFCs. Desalination efficiencies were 45%, 79%, and 46% when the algae were used as catholyte and 46%, 73%, and 16% when KFe(CN)6 was used as the catholyte at (35, 17.5, and 8.25 g/L of NaCl) respective salt concentrations. Confocal laser scanning microscopy imaging showed that the depth of the bacterial biofilm on the anode was about 65 μm. There were more viable bacteria on the biofilm surface and near the biofilm-electrolyte interface as compared to those closer to the anode surface. RB5 dye was more than 90% decolorized in 120, 165, and 225 min at 50, 100 and 200 mg L-1 dye concentrations, respectively. RBL4 at 50 and 100 mg L-1 took 225 and 300 min to decolorize, while 200 mg L-1 RBL4 dye was not decolorized at all. The reason may be substrate inhibition of the reductase enzyme or the selective transfer of electrons to the anode and not the dye. The results successfully demonstrated that the marine algae assisted biocatholyte can be used for efficient desalination in MDCs, but generates lower power as compared to the chemical catholyte. Biofilm growth on the anode creates a conductive layer, which can help overcome mass transport limitations in MFCs. Higher external resistance favors faster decolorization, and the reductive cleavage is faster with azo dyes than anthraquinone dyes.

The rapid growth of global energy consumption and simultaneous waste discharge requires more sustainable energy production and waste disposal/recovery technology. In this respect, microbial fuel cell and bioelectrochemical systems have been highlighted to provide a platform for waste-to-energy and cost-efficient treatment. Microbial fuel cell technology has also contributed to both academia and industry through the development of breakthrough sustainable technologies, enabling cross- and multi-disciplinary approaches in microbiology, biotechnology, electrochemistry, and bioprocess engineering. To further spread these technologies and to help the implementation of microbial fuel cells, this Special Issue, entitled “Microbial Fuel Cells 2018”, was proposed for the international journal Energies. This Special Issue mainly covers original research and studies related to the above-mentioned topic, including, but not limited to, bioelectricity generation, microbial electrochemistry, useful resource recovery, system and process design, and the implementation of microbial fuel cells.

In the context of wastewater treatment, Bioelectrochemical Systems (BESs) have gained considerable interest in the past few years, and several BES processes are on the brink of application to this area. This book, written by a large number of world experts in the different sub-topics, describes the different aspects and processes relevant to their development. Bioelectrochemical Systems (BESs) use micro-organisms to catalyze an oxidation and/or reduction reaction at an anodic and cathodic electrode respectively. Briefly, at an anode oxidation of organic and inorganic electron donors can occur. Prime examples of such electron donors are waste organics and sulfides. At the cathode, an electron acceptor such as oxygen or nitrate can be reduced. The anode and the cathode are connected through an electrical circuit. If electrical power is harvested from this circuit, the system is called a Microbial Fuel Cell; if electrical power is invested, the system is called a Microbial Electrolysis Cell. The overall framework of bio-energy and bio-fuels is discussed. A number of chapters discuss the basics – microbiology, microbial ecology, electrochemistry, technology and materials development. The book continues by highlighting the plurality of processes based on BES technology already in existence, going from wastewater based reactors to sediment based bio-batteries. The integration of BESs into existing water or process lines is discussed. Finally, an outlook is provided of how BES will fit within the emerging biorefinery area.

In view of the increased consumption of energy due to the proliferation of electronic devices, this book addresses the trends, similarities, differences and advances in fuel cells of both chemical and biological composition. Fundamentals of microbial fuel cells are described, accompanied by details surrounding their uses and limitations. Chapters on electricigens, microbial group investigations and performance, Rumen Fluid microbes and state-of-the-art advances in microbial fuel cell technology are discussed. The book elaborates upon analytical techniques used for biofilm characterization. It also includes chapters on MFC models that include plant-based MFCs, Algal/Fungi MFCs, MDCs and MFCs using animal waste. A critical review on the performance of MFC technology in field trials is offered in an exclusively dedicated section. By addressing one of the most promising sources for clean and renewable energy, this book fills a pressing need to understand a possible solution for meeting the energy demands in our highly advanced technical world.

Wastewater treatment is an energy intensive process that removes contaminants and protects the environment. While some wastewater treatment plants (WWTPs) recover a small portion of their energy demand through sludge handling processes, most of the useful energy available from wastewater remains unrecovered. Efforts are underway to harness energy from wastewater by developing microbial fuel cells (MiFCs) that generate electricity. Key challenges to the development of microbial fuel cells include inefficiencies inherent in recovering energy from microbial metabolism (particularly carbon metabolism) and ineffective electron transfer processes between the bacteria and the anode. We explored the prospects for constructing microaerobic nitrifying MiFCs which could exhibit key advantages over carbon-based metabolism in particular applications (e.g., potential use in ammonia-rich recycle streams). In addition, we evaluated nanostructure-enhanced anodes which have the potential to facilitate more efficient electron transfer for MiFCs because carbon nanostructures, such as nanofibers, possess outstanding conducting properties and increase the available surface area for cellular attachment. In the initial phase of this project, we investigated the performance of a novel nitrifying MiFC that contains a nanostructure-enhanced anode and that demonstrated power generation during preliminary batch testing. Subsequent batch runs were performed with pure cultures of Nitrosomonas europaea which demonstrated very low power generation. After validating our fuel cell hardware using abiotic experiments, we proceeded to test the MiFC using a mixed culture from a local wastewater treatment plant, which was enriched for nitrifying bacteria. Again, the power generation was very low though noticeably higher on the nanostructured anodes. After establishing and monitoring the growth of another enriched nitrifying culture, we repeated the experiment a third time, again observing very low power generation. In the absence of appreciable and repeatable power production from pure and mixed nitrifying cultures, we focused on the second major objective of the work which was the fabrication and characterization of carbon nanostructured anodes. The second research objective evaluated whether or not addition of carbon nanostructures to stainless steel anodes in anaerobic microbial fuel cells enhanced electricity generation. The results from the studies focused on this element were very promising and demonstrated that CNS-coated anodes produced up to two orders of magnitude more power in anaerobic microbial fuel cells than in MiFCs with uncoated stainless steel anodes. The largest power density achieved in this study was 506 mW m-2, and the average maximum power density of the CNS-enhanced MiFCs using anaerobic sludge was 300 mW m-2. In comparison, the average maximum power density of the MiFCs with uncoated anodes in the same experiments was only 13.7 mW m-2, an almost 22-fold reduction. Electron microscopy showed that microorganisms were affiliated with the CNS-coated anodes to a much greater degree than the noncoated anodes. Sodium azide inhibition studies showed that active microorganisms were required to achieve enhanced power generation. The current was reduced significantly in MiFCs receiving the inhibitor compared to MiFCs that did not receive the inhibitor. The nature of the microbial-nanostructure relationship that caused enhanced current was not determined during this study but deserves further evaluation. These results are promising and suggest that CNS-enhanced anodes, when coupled with more efficient MiFC designs than were used in this research, may enhance the possibility that MiFC technologies can move to commercial application.

This book is the second in a two-volume set devoted to bioelectrochemical systems (BESs) and the opportunities that they may offer in providing a green solution to growing energy demands worldwide. While the first volume explains principles and processes, in this volume established research professionals shed light on how this technology can be used to generate high-value chemicals and energy using organic wastes. Bioelectricity is generated in microbial fuel cells (MFCs) under oxygen-depleted conditions, where microbial bioconversion reactions transform organic wastes into electrons. Dedicated chapters focus on MFCs and state of the art advancements as well as current limitations. In addition, the book covers the use of microbial biofilm- and algae-based bioelectrochemical systems for bioremediation and co-generation of valuable chemicals. A thorough review of the performance of this technology and its possible industrial applications is presented. The book is designed for a broad audience, including undergraduates, postgraduates, energy researchers/scientists, policymakers, and anyone else interested in the latest developments in this field.