Treatment of dairy wastes with a microbial anode formed from garden compost

Abstract

Garden compost has already been identified as a source of efficient electro-active (EA) biofilms. The work described here consisted of lixiviating the compost and then using the leachate as a microbial source. This procedure gave promising results for the treatment of yogurt waste (YW) in a microbial fuel cell (MFC). Experiments performed in MFC set-ups were compared with electrochemical cells under polarization at +0.1 V versus SCE. Different parameters were tested to optimize the microbial anode. Preliminary acclimation of the compost microbial flora to YW was revealed to be unnecessary. Forming biofilms firstly in pure leachate before exposing them to YW showed that high concentrations of this type of substrate were detrimental to current generation. Pre-treatment of the electrode by pre-adsorbing YW led to a 10-fold increase in the current density. The highest current densities were obtained at 40 and 60 °C, revealing the diversity of electro-active microorganisms coming from soils. Values up to 1,450 mA m−2 were reached at 40 °C.