Enhanced electricity generation and organic matter degradation during three-chamber bioelectrochemically assisted anaerobic composting of dewatered sludge

Abstract

Composting microbial fuel cells can generate electricity from recycled organic waste at accelerated degradation rates. However, the problem of high internal resistance (R int ), which results in low power density, is a technical obstacle related to this process, and the preferential conversion of the organic fraction by bioelectrogenesis remains unclear. This study involved designing a novel three-chamber bioelectrochemically assisted anaerobic composting process (AnC BE,III ) to dispose of dewatered sludge (DS), which was operated at reduced internal resistance. The maximum power density of the AnC BE,III was higher (7.0–8.6 W/m 3 ) than that of the two-chambered AnC BE,II (4.7–5.7 W/m 3 ), with lower R int (63.8–88.5 Ω) than that of the AnC BE,II (78.8–98.5 Ω). At the end of composting, the AnC BE,III had higher total chemical oxygen demand (TCOD) removal (42.3 ± 0.5%) than the AnC BE,II (32.1 ± 0.5%). During electrogenesis, the dissolved organic carbon (DOC) [hydrophilic fraction and hydrophobic acid fraction of EBOM] (extracellular biological organic matter) was substantially removed, the hydrophobic neutral fraction of aromatic macromolecules was increasingly solubilized (by 13.2%), and the aromatic protein-like and humic acid-like substances were substantially removed. The results demonstrate that the increases in both the proton exchange area and cathode surface area in the AnC BE,III can enhance electricity generation and organic matter degradation. ? 2018 Elsevier B.V.