Electrochemical and bio-electrochemical treatment of baker's yeast effluents

In this study, electrochemical and bio-electrochemical oxidation where examined as possible methods for the treatment of untreated and biologically treated baker's yeast effluents, bearing large amounts of melanoidins. Experimental data showed that electrochemical oxidation, carried out in an electrolysis cell with a boron-doped diamond anode, strongly depends on the current density applied and the organic load is rapidly oxidized to CO2 without the formation of intermediates leading to almost complete discoloration and COD removal. Color removal of the treated and untreated effluents was almost complete after 200 min of oxidation at a current density greater than 132 A/m2. COD and TOC of both effluents were also successfully reduced under the same experimental conditions. The acidic pH favours oxidation more than neutral or alkaline one. On the other hand, bio-electrochemical treatment via a microbial fuel cell (MFC) with carbon felt electrodes, was proven less efficient on the discoloration of the untreated effluent, but exhibited a significant effect on the reduction of COD which reached 40%. The addition of 0.4% v/v ABTS+ mediator in the anode chamber enhanced the power output of the cell up to 0.018 W/m2 and the removal of COD up to 40% but further increase had a negligent effect on MFC's performance.