The biochemical and electrochemical characteristics of a microbial fuel cell used to produce electricity from olive mill wastewater

Abstract

Olive Mill Wastewater (OMW) is a hard to treat by-product with low biodegradability and high toxicity due to its high phenolic content. Ιn the present study, OMW after centrifugation, was used for combined electricity and methane production. A three-air cathode single-chamber MFC operating continuously was set up for the exploitation of the liquid fraction of OMW obtained via centrifugation, while batch anaerobic digestion (AD) was employed for valorization of the solid residue. The MFC was also operated with a glucose-based medium, supplemented with phenolics, in order to assess the effect of phenolic compounds on its performance. In order to highlight the mechanisms and determine the limitations and electrochemical losses, electrochemical impedance spectroscopy experiments were conducted, using both the synthetic and the real wastewater. The experimental results showed that power densities of 0.7–2.0 W/m3 OMW were achieved in the MFC, corresponding to an energy of 6.2 MJ/m3 OMW while 664 MJ/m3 OMW could be obtained through AD of the solid residue. However, as the energy which could be recovered directly from AD of OMW was calculated as 1439 MJ/m3 OMW, indicates that it is a competitive technology for OMW treatment and valorization.