Performance of pilot scale plug flow microbial fuel cell for sustainable wastewater treatment and energy recovery

Abstract

Wastewater is increasingly considered a resource rather than a problem. This study investigates the rapidly developing Microbial Fuel Cell technology and its potential to be used in an industrial scale and environment in the context of the whisky industry and to be used as an alternative or complementary sustainable wastewater treatment process. This study describes the development of a 122 litre multi-electrode open air cathode Microbial Fuel Cell. Throughout this study the reactor’s performance is assessed on two levels; energy recovery and effluent quality. During initial studies the principle of the MFC’s ability to treat whisky distillation by-products was established. The reactor was operated directly on diluted spent wash in ambient Scottish temperatures. During successful start-up, no correlation was found to temperature. During long-term operation, a positive correlation was found between temperature and the positive energy balance achieved by the MFC while tCOD removal efficiency was maintained at approximately 83 %. The reactor was further optimised in regards to electrical connections, thus its electrical performance which was also validated through a bench scale study. The successful initial experiments led to the integration of an operationally optimised pilot study in a local whisky distillery. The pilot set-up was successfully operated complementary to an anaerobic digester for over one year in the industrial environment achieving energy savings and a sustainable tCOD removal efficiency of over 80 %. Latterly, a simplified electrochemical model was examined to describe the performance of the MFC to be further developed. This study concludes that the nature of industrial wastewater treatment is a complex subject and equally so is the multi-disciplinary MFC technology. The MFC developed for this study and the industrial experience gained contributes towards a more sustainable, energy saving and efficient treatment technology with the potential to be used complementary to existing technologies.