Debajyoti Bose

Energy Recovery with Microbial Fuel Cells: Bioremediation and Bioelectricity

This chapter presents an overview on microbial fuel cells (MFCs) as a novel electrogenic reactor systems for simultaneous treatment of wastewater and generation of bioelectricity. MFCs work on the principle that organic matter present in wastewater serves as a primary substrate for the bacteria to consume and release electrons, facilitating the treatment of wastewater with simultaneous generation of power. Microbes in the anode chamber generate protons (H+) and electrons (e−) through reactions by decomposing the rich organics present in the wastewater and in the process treating the wastewater and producing a value added product which is bioelectricity. When these protons travel through the membrane and the circuit, respectively, power is generated from the system. Given the non-renewable aspect and polluting nature of fossil fuels, MFCs have generated interest among several research communities around the world. Following a historical approach toward this technology, the chapter discusses the various types of microbial fuel cells prevalent and compares the different MFC designs used. The role of proton exchange membrane separating the anodic and cathodic chambers is also explained. It focusses on the principle and working of an MFC and describes the instrumentation and procedure for reporting data. Additionally, the chapter presents benefits, drawbacks, and future scope of research in this field.

Analysis of Biomass in the Indian State of Gujarat for Sustainable Pellet Production

Energy from biomass has emerged as a promising source of decentralized energy production from developing countries. This paper highlights the importance of solid biofuel or pellets in the context of green energy. These can be used in co-firing with coal and other heating applications. Assessment is done for certain raw materials which do not create food and fodder conflict in the Indian state of Gujarat. Raw material includes agricultural residues available from that region. Pellets manufactured have low sulfur and chlorine content.

Step Towards E-Waste Management (STEM)

The growing energy insecurity has brought dire need of energy recovery through processes that can utilize each and every electronic components from materials used in the contemporary world. Along with the demand of electronics and electrical products, the generation of e-waste is increasing at tremendous rate. However, the technology for safe disposal or recycling of such matter still remains a challenging issue, given the lack of awareness, infrastructure and other developments. This can cause severe damage to the ecology. Present work discusses such issues and how e-waste can be effectively managed and acclimatized. The handling of such wastes from the solar photovoltaics industry has also been reviewed, and an attempt has been made to speculate the spectrum of possibilities for safe disposal of e-waste, thereby having a sustainable energy utilization system which can explore the possibilities of harnessing electronic products without damaging the environment.

Sustainable power generation from sewage and energy recovery from wastewater with variable resistance using microbial fuel cell

Wastewater from sewage sources contribute significantly to water pollution from domestic waste; one way to recover energy from these sources while at the same time, treating the water is possible using Microbial Fuel Cell. In this work, a two chambered microbial fuel cell was designed and fabricated with carbon cloth electrodes and Nafion-117 membrane, having Platinum as the catalyst. Wastewater from an organic load of 820 ± 30 mg/l reduced to around 170 mg/l, with the change in pH from 7.65 ± 0.6 to 7. 31 ± 0.5; over the time of operation the biochemical oxygen demand from an initial 290 ± 30 mg/l reduced to 175 ± 10 mg/l. Open circuit voltage was achieved mostly between 750-850 mV, with inoculated sludge produced a peak open circuit voltage of 1.45 V between fed-batch cycles. For characterization of power generated, polarization curves are evaluated with varying resistance to examine system stability with varying resistance. The current density and power density are reported to peak at 0.54 mA/m2 and 810 ± 10 mW/m2 respectively. The development of stable biofilms on the anode contributes to the power generation and was evaluated using microscopic analysis, this shows bacteria present in wastewater are electroactive microbial species which can donate electron to an electrode using conductive appendages or nanowires, while consuming the organic matter present in the wastewater. Such systems employ microbial metabolism for water treatment and generate electricity.

Biomass pyrolysis in a twin-screw reactor to produce green fuels

ABSTRACT This paper highlights work done with a twin-screw reactor or auger reactor, with temperature profiles of near 500 °C, and sawdust and bagasse biomass. Analysis of the solid biofuel, i.e. biochar, is given, along with proximate and ultimate analysis of biomass feedstocks. System limitations are profiled and issues related to bio-oil production are addressed. Design changes in the existing system are suggested, using SOLIDWORKS software to optimize the existing design where this experimentation has been done. It is believed the design changes would make the facility more efficient. Nitrogen gas is used to maintain the velocity profile of the biomass particles inside the reactor. This work does not have the food vs fodder conflict as the biomass feeds used are primarily wood wastes and sugar industry by-products.

Auger reactor for biomass fast pyrolysis: Design and operation

Pyrolysis represents a process of renewable energy recovery, using thermochemical methods of combustion it is possible to heat biomass i.e. residues such as sawdust, bagasse and pine wood to obtain a liquid fuel known as bio-oil. This bio-oil finds application in Chemical industry and suitable upgradation can make it a petroleum substitute. The byproduct of this process is a solid residue known as bio-char, which has the potential to be used as an excellent climate change mitigation tool if mixed with soil, acts as an excellent amendment. This paper highlights the work done with a Twin screw reactor or auger reactor, temperature profiles of near 500°C has been studied, biomass used has been sawdust and bagasse. Analysis for the solid bio-fuel i.e. biochar has been given along with proximate and ultimate analysis of biomass feedstocks. System limitation has been profiled and issues related to bio-oil production have been addressed. Design changes have been suggested in the existing system using Solidworks software to optimize the existing design where this experimentation has been done. It is believed the design changes would make the facility more efficient. Nitrogen gas has been used to maintain velocity profile of the biomass particles inside the reactor. This work does not have the food vs fodder conflict as it shows biomass feeds used are primarily wood wastes and sugar industry by-products.