Properties of electrode-attached biofilms for application to microbial fuel cells
Jana, Partha sarathi
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Energy, in any form, plays the most important role in the modern world. We have been dependent on conventional energy sources such as coal and petroleum product for quite a long time. Therefore, there is an alarming need for more environmentally sustainable alternative energy resources. This thesis focuses on studies of microbial fuel cells (MFC). MFC devices use electro active bacteria to oxidize organic substrates degrading wastes and generating electricity. In the present study the effect of bacterial biofilms thickness, charge transport and power generation was studied in single chamber electrochemical cell using acetate as an electron donor. The thicker biofilms display higher charge transport diffusion co-efficient than that in thinner films, as increased film porosity of these films improves ion transport, required to maintain electro-neutrality upon electrolysis. Quartz crystal microbalance (QCM) technique was used to understand the effect of initial electro active bacterial attachment and deposition on gold electrode. It was observed that the viscoelastic properties of the biofilm increased as function of time leading to the better current generation. An attempt has been made to produce low cost MFC from the earthen plate, without involving any costly membrane. The material of the earthen plate used is found to be effective for ion transfer. The earthen plate separator is 99 % cheaper than the Nafion membrane, showing promise as an alternate separator for application to MFC technology. The proteomics analysis of Geobacter sulfurreducens growth on carbon cloth electrodes versus planktonic cells revealed different protein expression depending on the nature the of terminal electron acceptor. The majority of the proteins are localized in the cell membrane and involved in energy metabolism, binding and transport functional categories. In the present study the effect of influent chemical oxygen demand (COD) concentration (2000-4000 mg/L) and feed temperature (15 ºC - 32 ºC) on COD removal efficiency and power generation was studied in dual chambered MFC treating synthetic and real dairy wastewater. The results demonstrate the feasibility of novel MFC configuration for an effective wastewater treatment technology which ensures better reliable effluent quality.