Harvesting Energy Using Compost as a Source of Carbon and Electrogenic Bacteria

Compost is widely used to improve soil fertility for its chemical-physical properties, with particular regard to the abundance of humic substances. Compared to the untreated organic solid waste, the use of compost in Microbial Fuel Cells (MFCs) could offer different advantages like the strong reduction of fermentative processes. The use of compost in MFCs in combination with soil or mixed with other substrates had been reported by some researchers to improve the performance of MFCs fed with agro-industrial residues and plant-MFCs. In this chapter, we report the results of an experiment carried out using a compost of vegetable residues as feedstock in a single chamber, air cathode MFCs. We investigated the behaviour of two MFCs serially connected, the possibility to use compost as a long-term source of energy in MFCs, the influence of cathode surface /cell volume ratio on MFCs performance in terms of power and current density. Our results showed for MFCs serially connected a maximum PD and CD of 234 mW/m 2 and 1.6 A/m 2 respectively, with a maximum OCV of 557 mV. Unexpectedly, the compost-based MFCs kept significant electric outputs (854 mV, 467 mW/m 2 kg and 114 mA/m 2 kg) after being reactivated two years later its setup thus demonstrating its potential as long-term operation energy system.