Enhancement of anaerobic digestion of dairy wastewater by addition of conductive materials with or without the combination of external voltage application

Abstract

BACKGROUND

The addition of conductive materials or the application of external voltage is a promising novel methodology to enhance methane production in anaerobic digesters. However, there is limited knowledge about their individual or combined effects on the anaerobic digestion of dairy wastewater. The aim of this study was to examine the effects of granular activated carbon (GAC) or magnetite addition and external voltage application, both individually and in combination, for the anaerobic digestion of real, undiluted dairy wastewater.

RESULTS

The results showed that the estimated maximum methane production rate increased significantly (P < 0.05) from 143 ± 8 mL gVS_added⁻¹ day⁻¹ in the control reactors to 163 ± 11 mL gVS_added⁻¹ day⁻¹ and 166 ± 11 mL gVS_added⁻¹ day⁻¹ in the reactors containing GAC, with or without the combination of external voltage, respectively. The addition of GAC, in both cases, resulted in higher consumption rate of acetate, indicating a promotion of the methanogenesis step. By contrast, the application of external voltage or the addition of magnetite had no significant effect on either methane production rate nor methane yield. Moreover, the analysis of the microbial community showed that the addition of GAC resulted in the enrichment of Desulfobacterota, Methanosarcina, Candidatus Methanofastidiosum and Methanolinea.

CONCLUSION

Overall, GAC addition seems a promising strategy to increase methane production in anaerobic digesters treating dairy wastewater. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).