Effects of biowaste-derived biochar on the electron transport efficiency during anaerobic acid orange 7 removal

Abstract

In this study, different biochar (based on different pyrolytic temperatures and iron dosage) were prepared, characterized and used as individual additives for promoting acid orange 7 (AO7) anaerobic digestion. After X-ray diffraction (XRD), fourier transform infrared spectrometer (FTIR) characterization, 600 °C was proved to be the preferred temperature. Subsequently, biochar pyrolyzed at 600 °C with different iron dosage were added into five anaerobic reactors. Results showed that COD removal efficiency reached the maximum value (88.5%) with the presence of 600-1 biochar, which was 19.0% higher than control reactor (without biochar added). Further analysis indicated that more functional groups were found in 600-1 biochar could effectively improve the electron accepting capacities (EAC) and electron donating capacities (EDC). Combined with the enrichment of exoelectrogens related to syntrophic metabolism, it can be concluded that the addition of biochar could effectively improve the electron transfer efficiency which would be beneficial for AO7 removal.