Bio-Electrochemical Performance of a Ceramic Microbial Fuel Cell Treating Kitchen Waste Leachate: Effect of Organic Loading Rate and Anode Electrode Surface Area

Abstract

Performance evaluation of a ceramic microbial fuel cell (CMFC) by varying organic strength, hydraulic retention time (HRT) and anode electrode surface area (AESA) to treat leachate generated from acidogenesis of kitchen waste (KW) was studied by the central composite design of experiment. The increase in organic loading rate (OLR) positively affected power density (PD) while negatively influencing organic removal and coulombic efficiency (CE). This behavior is possible due to substrate inhibition and the coercive effect of low HRT, i.e., substrate washout, biofilm abrasion, and reduced contact period, while at high HRT, the volatile fatty acid (VFA) degradation improved. Since acetic acid is the final product of long-chain VFAs degradation, a pseudo consumption order for VFAs was obtained: butyric > propionic > acetic. The AESA aided organics removal and PD but had a negligible effect on CE. According to ANOVA, the COD removal was linearly modeled, while PD and CE were quadratic. The validation runs (VR) proved efficient as the highest COD removal was for VR2 (83.7 ± 3.6%), while maximum PD and CE values obtained were 0.224 ± 0.02 W/m³ and 2.62 ± 0.33%, respectively, for VR3, supported by the lower anode potential.

Key findings

• ▸Increasing organic loading rate positively affected power density, but negatively influenced organic removal and coulombic efficiency.
• ▸High hydraulic retention times improved volatile fatty acid degradation, with a pseudo consumption order for VFAs: butyric > propionic > acetic.
• ▸Anode electrode surface area aided organics removal and power density, but had a negligible effect on coulombic efficiency.

Keywords

Identifiers

DOI

10.3390/fermentation8100544

Journal

Fermentation

Year

2022