Pyrolyzed waste stream and biochar performance evaluation in food waste anaerobic digestion

Abstract

The requirements for enhanced technologies, such as pyrolysis and anaerobic digestion, are crucial to improve food waste and sewage sludge and address the difficulty in disposing of hardly biodegradable residues. The pyrolysis process was applied to two waste streams, namely hardly biodegradable residues and sewage sludge, at 500 °C with a heating rate of 25 °C min−1 to obtain hardly biodegradable residues biochar (DBR-Char) and sewage sludge biochar (SS-Char). The two biochars were then used as additives during anaerobic digestion of food waste treatment to enhance biogas production and reactor robustness to achieve average methane contents in biogas up to 75% compared with the control. Biochar addition also improved process stability, with the Methanosaeta/Methanothrix 99.55% in the CK1 (reactor with inoculum, food waste, and DBR-Char) and 98.13% in the CK2 (reactor with inoculum, food waste, and SS-Char) as the dominant genera among the anaerobic consortia. This study averted the hardly biodegradable residues and sewage sludge disposal challenges via pyrolysis and offered biochar utilization to promote reactor stability and biogas production in food waste fermentation.