The role of biochar treatment in desulfurization and acid reduction during anaerobic digestion of faecal sludge and food waste.

Abstract

This research project explores an innovative method to treat biogas produced from faecal sludge (FS) and food waste (FW) in a ratio of 1FS:3FW respectively by using biochar to reduce hydrogen sulphide (H₂S) emissions and lower the biogas’s acidic properties.The two substrates were fed in ratios of 1:3 (FS: FW) into the reactors and also inoculum collected from already running reactors was added to the bio digester in a ratio of 1:3 (inoculum: substrate level). The overall findings reveal that the mixtures and substrates had a pH between 6.42 and 8.05, indicating a mildly acidic to alkaline mixture. While the MC content ranged from 60.60% to 83.97%, in contrast to the ash content, which varied from 27.58% to 56.50%, the VS content ranged from 44.50% to 72.43%. Biogas, typically produced through the anaerobic digestion of organic waste, contains harmful gases such as hydrogen sulphide, which pose significant environmental, contribute to corrosion of industrial equipment and reduce its effectiveness as a renewable energy source. Biochar, a carbon-rich material created from the pyrolysis of organic matter, has been shown to possess adsorptive and neutralizing properties that can be used to address these issues.In this study, biochar will be introduced as a treatment medium for biogas during its production. Results from the study reveal that as bio char dosage increased, hydrogen sulfide (H₂S) concentrations in the produced biogas notably declined e.g. 5 % reduced H₂S by roughly 10–25 % at day 20 and up to 30 % by day 26 thereby lowering microbial toxicity and corrosion risk. The primary aim is to investigate the capacity of biochar to adsorb and neutralize hydrogen sulphide from the biogas in real-time, as well as to reduce the biogas's acidity through surface interactions and chemical processes.