These results were consistent with reports on reduction of ohmic resistance of cells by decreasing inter-electrode distance. Also, the volumetric power PV output was higher for the MFC-A than for MFC-B; this was congruent with doubling the σ in the MFC-A compared to MFC-B. Yet, power density PAn delivered was higher for MFC-A only when operated with SR-In and Ab-In, but not with M-In. The MFC-A loaded with SR-In showed a substantial improvement in PV (ca. 13-fold, probably due to the combined effects of increased σ and decreased of Rint) and a 6.4-fold jump in PAn compared to MFC-B. The improvement was higher than the expected improvement factors (or algebraic factors; 6.5 improvement expected for PV due to combined effects of increase of σ and lowering the Rint; 3.25 improvement expected for PAn due to lowering the Rint).
Our results point out to continuing work using the two-set, sandwich-electrode MFC and sulphate-reducing inoculum as a departing model for further studies on effects of inoculum enrichment and electrode material substitution on cell performance. Also, the MFC-A model seems to hold promise for future studies of bioelectricity generation and pollution abatement processing leachates produced during biohydrogen generation in dark fermentation processes of organic solid wastes.