Copper removal from wastewater and electricity generation using dual-chamber microbial fuel cells with shrimp shell as the substrate

Abstract

High-content solid waste (HCSWs) contains numerous polysaccharides and is widely recognized as an energy-generating substance. However, detailed studies on the use of HCSWs as substrates in microbial fuel cells (MFCs) to generate electricity and remove heavy metals from wastewater are scarce. In this study, the effects of shrimp shell (SS) and sodium acetate (SA), which are complex and simple substrates, respectively, as anodic carbon sources on the electricity generation performance of dual-chamber MFCs and the removal of Cu at the cathode were investigated. The structural characteristics of the anodic microbial communities of the MFCs were analyzed in terms of substrate type and concentration. The results demonstrated that the maximum voltage (206 mV) and maximum power density (28.82 mW/m2) of the MFC-SA were higher than those of the MFC-SS groups. The operating time and maximum power density increased with increasing SS concentration, and the maximum power density reached 24.75 mW/m2 at an SS concentration of 16 g/L. The Cu2+ ions in the catholyte were primarily reduced to elemental Cu and small amounts of Cu2O or CuO. The higher the concentration of SS, the higher the Cu removal rate, the greater the total amount of Cu removed, and the higher the MFC removal capacity. Pseudomonas was the only electroactive microorganism in the raw sludge, whereas Geobacter, Corynebacterium, Clostridium, Desulfovibrio, and Desulfosporosinus were detected in the MFCs at the end of the experiment. The relative abundance of the electroactive microorganisms increased from 19.4% to 36.0% as the SS concentration increased from 2 to 16 g/L. These results suggest that SS can be used as substrate for HCSW degradation to provide the energy required for heavy-metal reduction.