Relation of anodic and cathodic performance to pH variations in membraneless microbial fuel cells

One-compartment (membraneless) microbial fuel cells (MFCs) are effective tools to test new bio-technology at a laboratory level. More efforts in MFC design and materials are necessary to move from laboratory tests to real applications.In such a context, this paper presents the experimental results that investigate pH variations of three single chamber and membraneless MFCs having positive and negative electrodes made of graphite-based materials without any addition of chemical catalysts. MFCs were built and operated with raw wastewater (inoculum) and sodium acetate as substrate. The progression of the power in the MFC and the relationship between performances and induced pH variation (from pH 6.7 to 10.2) will be discussed. A general connection between SEM images, chemical analyses, pH trends and reactions in the MFCs will be attempted, by connecting all processes with thermodynamic and chemical equilibria considerations.

► The effect of pH on three MFCs was investigated.
► Chemically uncatalyzed carbon bio-cathodes were built and tested.
► The role of anaerobic bacteria was assessed.
► A general discussion on carbonate precipitation role on pH was addressed.
► Thermodynamic calculations regarding sulfate and acetate substrates were performed.