Adaptation of biofuel cell technology for electricity generation from wastewater and lactose measurement : a thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy

Abstract

Biofuel cell (BFC) is an emerging renewable technology that can perform high direct energy conversion efficiency to electricity. BFC system uses low energy density sources, such as organics in wastewater and converts them into electricity. The system is based on biological catalysts such as microorganisms and enzymes, which are capable of consuming the organics in the sewage for metabolism. In the process, the BFC system will convert the organics in the wastewater and reduce the biological oxygen demand of the sewage to a safe level before it is released to the environment. Nevertheless, commercialisation of BFC applications are still a long way to go due to many weaknesses that have to be overcome. Culturing exoelectrogenic bacteria and applying new materials to enhance catalytic process in microbial fuel cell (MFC) are some of the options to improve MFC operation. The aims of this study are two-fold: To develop (i) a MFC for electricity generation from wastewater by bacteria isolated from a trickling filter, and (ii) an enzymatic fuel cell (EFC) for continuous measurement of lactose concentration in dairy wastewater as well as electricity generation. This thesis shows that the multi-cultured bacteria could generate electricity after 30 days exposure to oxygen at a concentration of 7.5 ppm and that the fabricated graphite-epoxy composite anodes possess the desired characteristics of a good electrode. Such fabricated electrodes can be prepared within a very short time-span compared to commercial electrodes. These electrodes are cheap and flexible for surface modification. However, due to inherent high resistance of the graphite-epoxy composite, it was unable to generate as much current intensity as commercial material electrodes. This study has highlighted several areas that can be further explored such as reducing inherent resistance in graphite composite electrode and the potential use of combined multi-walled carbon nanotube (MWCNT)-diazonium salt within graphite matrix as a reusable high performance electrode.