Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Bioelectrochemical treatment system (BET) with anoxic anodic microenvironment was studied with chemical wastewater (CW) in comparison with anoxic treatment (AxT, sequencing batch reactor (SBR)) with same parent anaerobic consortia. BET system documented relatively higher treatment efficiency at higher organic load (5.0kgCOD/m3) accounting for COD removal efficiency of (90%) along with nitrate (48%), phosphate (51%), sulphates (68%), colour (63%) and turbidity (90%) removal, compared to AxT operation (COD, 47%; nitrate, 36%; phosphate, 32%; sulphate, 35%; colour, 45% and turbidity, 54%). The self-induced bio-potential developed due to the electrode assembly in BET resulted in effective treatment with simultaneous bioelectricity generation (631mA/m2). AxT operation showed persistent reduction behaviour, while simultaneous redox behaviour was observed with BET indicating balanced electron transfer. BET operation illustrated higher wastewater toxicity reduction compared to the AxT system which documents the variation in bio-electrocatalytic behaviour of same consortia under different microenvironment. © 2013 Elsevier Ltd.

CO2 Research and Green Technologies Centre

Vellore Campus

World University root node

Bioresource Technology

Anoxic bio-electrochemical system for treatment of complex chemical wastewater with simultaneous bioelectricity generation

Influence of inherent buffering nature of real field pharmaceutical wastewater (PW) was evaluated in a microbial fuel cell (MFC) at varying organic loads (OL1-OL4). Dynamics of in situ buffers present in the wastewater during remediation enhanced the electrogenic activity. Improvement in power density (PD) and open circuit voltage (OCV) was observed as the organic load increased from OL1 to OL4 (PD of 62.45 to137 mW/m2; OCV-245 to 324 mV). It was concluded from the buffering capacity (β) profiles that base β values were relatively more stable than acid β values indicating the dynamics of nutrients and salts present in PW. pH increased with increase in OL documenting improvement in power output and waste remediation. Present study depicted an optimum pH range suitable for effective operation of MFC for bioelectrogenesis using PW as substrate. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 454-462, 2014 © 2013 American Institute of Chemical Engineers Environ Prog.

Environmental Progress and Sustainable Energy

In situ system buffering capacity dynamics on bioelectrogenic activity during the remediation of wastewater in microbial fuel cell

Microbial fuel cells (MFC) are bio-catalyzed electrochemical hybrid systems which function by converting chemical energy to electrical energy through a cascade of redox reactions in the presence of biocatalyst. The research on MFC has been intensified in the last few years due to its inherent ability to produce sustainable energy from renewable organic waste. The current review depicts an overview on the fundamental operational mechanism of MFC encompassing electromotive force, electron delivery, electron transfer, losses encountered during operation, etc. The specific function of physical, biological and operational factors on the bioelectrogenic activity is elaborated. In addition, the strategies to regulate the process towards enhancing the performance of the system have been discussed. The potential applications of MFC for energy generation, waste remediation and value added product recovery have also been elaborated. © 2014 Elsevier Ltd.

Renewable and Sustainable Energy Reviews

Microbial fuel cell: Critical factors regulating bio-catalyzed electrochemical process and recent advancements

Microbial catalyzed electrochemical systems (MCES) have been intensively pursued in both basic and applied research as a futuristic and sustainable platform specifically in harnessing energy and generating value added bio-products. MCES have documented multiple/diverse applications which include microbial fuel cell (for harnessing bioelectricity), bioelectrochemical treatment system (waste remediation), bioelectrochemical system (bio-electrosynthesis of various value added products) and microbial electrolytic cell (H2 production at lower applied potential). Microorganisms function as biocatalyst in these fuel cell systems and the resulting electron flux from metabolism plays pivotal role in bio-electrogenesis. Exo-electron transfer machineries and strategies that regulate metabolic flux towards exo-electron transport were delineated. This review addresses the contemporary progress and advances made in MCES, focusing on its application towards value addition and waste remediation. © 2014 Elsevier Ltd.

Microbial catalyzed electrochemical systems: A bio-factory with multi-facet applications

The energy gain in microbes is driven by oxidizing an electron donor and reducing an electron acceptor. Variation in the electron acceptor conditions creates a feasibility to harness energy. In order to support the microbial respiration, electrons will transfer to the exocellular medium toward the available electron acceptor, especially in the absence of oxygen. The microbes can use a wide range of electron acceptors such as metals, nutrients, minerals, etc., including solid electrodes. When the microbes use the solid electrode as electron acceptors, the setup is called microbial fuel cell (MFC) and the electrons can be harvested and used for different applications. MFC can be defined as a microbially catalyzed electrochemical system which can facilitate the direct conversion of substrate to electricity through a cascade of redox reactions, especially in the absence of oxygen. Linking the microbial metabolism to anode and then transmitting the electrons to cathode generates a net electrical power from the degradation of available electron donor. This concept of MFC operation has expanded considerable interest in the recent research due to its application in the energy recovery from wastewater. Microbes in MFC can also use variety of organic or inorganic electron donors as well as acceptors to produce a surfeit of desirable biofuels or biochemicals which is termed as microbial electrosynthesis. Apart from the electrogensis, the applications of MFC are widespread in different fields including waste/wastewater remediation, toxic pollutants/xenobiotics removal, recovery of commercially viable products, sequestration of CO2, harvesting the energy stored in marine sediments, desalination, etc. In this chapter, an attempt was made to bring out all the existing applications of MFC into one platform to make a comprehensive understanding on the inherent potential of microbial metabolism, when the designated electron acceptor is present. © 2013 Springer-Verlag Berlin Heidelberg. All rights are reserved.

Biofuel Technologies: Recent Developments

Microbial fuel cells for sustainable bioenergy generation: Principles and perspective applications

Relative change in the electrogenic activity and potential losses during electron transfer in microbial fuel cell (MFC) was elucidated using real-field recalcitrant pharmaceutical wastewater as anolyte by varying substrate/organic load (OL1, 1.98; OL2, 3.96; OL3, 5.93, OL4, 7.98 kg COD/m3). Increase in organic load showed improvement in electrogenic activity (OL4: 346 mV, 205.61 mW/m2; OL3: 320 mV, 158.58 mW/m2; OL2: 290 mV, 112.87 mW/m2; OL1: 256 mV, 72.60 mW/m2). Both activation and ohmic losses showed decrement with increase in organic load while concentration losses depicted increment. Improvement in power output was non-linear with increase in organic load due to the anodic over potentials, described as electron transfer resistances and potential losses. Bio-electrochemical analysis also depicted the electron losses in terms of electron discharge and energy generation with the function of varying organic load. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

International Journal of Hydrogen Energy

Electrogenic activity and electron losses under increasing organic load of recalcitrant pharmaceutical wastewater

Voltage sag, regain and their stabilization phases were evaluated with time across load (closed circuit) and absence of load (short circuit) to understand the stability of the bio-electrochemical system (BES) under varying organic loads (OL). Closed circuit operation showed good stability along with the electrogenic activity over short circuit operation during both the sag and regain phases due to the regulated electron flow in the closed circuit. Relative change in voltage with time (dV/dt) was observed to be decreasing with increasing OL in the zone of sag, while it was observed to be increasing with increase in OL during the zone of regain. However, the change in dV/dt was not proportional with increasing OL during both the sag and regain phases indicating the influence of OL on the biocatalytic activity. Bio-electrocatalytic evaluation through Tafel analysis showed a gradually decreasing reductive slope from OL1 (0.62 V/dec) to OL4 (0.516 V/dec) indicating higher electrocatalytic activity towards reduction. While, the oxidative slope increased from OL1 (0.085 V/dec) to OL2 and was almost similar with further increment in the OL (0.099 ± 0.002 V/dec) which indicates marginal change in the electrocatalytic activity during oxidation even with increasing OL. Exchange current density from Tafel analysis was also observed to increase with increase in OL (OL1, 7.86 mA m -2; OL2, 8.33 mA m -2; OL3, 9.59 mA m -2; OL4, 11.77 mA m -2). Polarization resistance showed a decreasing trend with increasing OL (OL1, 12.23 Ω to OL4, 9.8 Ω) resulting in higher electron transfer. © 2012 The Royal Society of Chemistry.

RSC Advances

Evaluation of voltage sag-regain phases to understand the stability of bioelectrochemical system: Electro-kinetic analysis

Functional behavior of anoxic-aerobic-anoxic microenvironment on azo dye (C.I. Acid black 10B) degradation was evaluated in a periodic discontinuous batch mode operation for 26 cycles. Dye removal efficiency and azo-reductase activity (30.50 ± 1. U) increased with each feeding event until 13th cycle and further stabilized. Dehydrogenase activity also increased gradually and stabilized (2.0 ± 0.2 μg/ml) indicating the stable proton shuttling between metabolic intermediates providing higher number of reducing equivalents towards dye degradation. Voltammetric profiles showed drop in redox catalytic currents during stabilized phase also supports the consumption of reducing equivalents towards dye removal. Change in Tafel slopes, polarization resistance and other bioprocess parameters correlated well with the observed dye removal and biocatalyst behavior. Microbial community analysis documented the involvement of specific organism pertaining to aerobic and facultative functions with heterotrophic and autotrophic metabolism. Integrating anoxic microenvironment with aerobic operation might have facilitated effective dye mineralization due to the possibility of combining redox functions. © 2012 Elsevier Ltd.

Acid azo dye remediation in anoxic-aerobic-anoxic microenvironment under periodic discontinuous batch operation: Bio-electro kinetics and microbial inventory

Biocatalyst behavior was comparatively evaluated under diverse microenvironments viz., self-induced electrogenic (bioelectrochemical treatment, BET) and anaerobic treatment (AnT) microenvironments, with real-field pharmaceutical wastewater. Relatively higher treatment efficiency was observed with BET (COD removal, 78.70%) over AnT (32%) along with the power output. Voltammetric profiles of AnT showed persistent reduction behavior, while BET depicted simultaneous redox behavior. BET operation documented significantly higher bio-electrocatalytic activity (k app, 245.22s -1) than AnT (k app, 7.35s -1). The electron accepting conditions due to the presence of electrode in the BET might contributed to higher electrogenesis leading to enhanced substrate degradation along with the removal of multiple pollutants accounting for the effective reduction of toxicity levels of wastewater. Even at higher organic loads, BET operation showed good treatment efficiency without process inhibition. Introduction of electrode-membrane assembly in anaerobic microenvironment showed significant change in the electrocatalytic behavior of biocatalyst resulting in enhanced treatment of complex wastewater. © 2011 Elsevier Ltd.

Biocatalyst behavior under self-induced electrogenic microenvironment in comparison with anaerobic treatment: Evaluation with pharmaceutical wastewater for multi-pollutant removal

Biologically catalyzed electrochemical treatment of real field dairy wastewater in association with power generation was studied in single chamber non-catalyzed microbial fuel cell (MFC, open-air cathode). The performance was evaluated at four organic loads employing anaerobic mixed consortia as anodic biocatalyst. Experimental data illustrated the integrated function of MFC to harness bioelectricity from the treatment of dairy wastewater. Along with good substrate degradation (chemical oxygen demand (COD), 95.49%), MFC also documented good removal of proteins (78.07%), carbohydrates (91.98%) and turbidity (99.02%). A steady increase in MFC performance was observed with increase in substrate load. Maximum volumetric power production (1.10W/m3; 308mV; 1.78mA) was observed at 4.44kgCOD/m3. MFC performance as power generator was characterized based on polarization behavior, cell potentials, cyclic voltammetric analysis and sustainable power estimation. In view of inherent advantages of the process, if optimized and understood well, this integrated approach can be a good replacement for the conventional biological and electrochemical wastewater treatment processes. © 2010 Elsevier B.V.