Effect of sludge biochar on methane production from anaerobic granular sludge

Biochar has been documented to enhance the performance of anaerobic digestion, a technique extensively uti-lized in the initial treatment of highly concentrated wastewater. However, the impact of biochar derived from sewage sludge on the digestion efficiency of anaerobic granules has not been previously explored. In this investigation, we introduced sewage sludge-derived biochar into the anaerobic digestion process, incorporating it with anaerobic granular sludge, to assess its effect on methane generation. As the pyrolysis temperature escalated, there was an increase in both the levels of heavy metals and the pH, factors that hindered methane generation from anaerobic granules. Methane generation from the established anaerobic granular sludge remained unaffected by the presence of biochar. However, concerning the free anaerobic microorganisms responsible for methane production in the solution, biochar expedited electron transfer while impeding methane production by channeling more electrons towards sulfate reduction. The outcomes of this study offer a theo-retical basis for the utilization of sewage sludge-derived biochar in bioreactor technology based on granular anaerobic sludge.