Synergistic effect of bulking agents and biodegradation on the pyrolysis of biodried products derived from municipal organic wastes: Product distribution and biochar physicochemical characteristics

Abstract

Derived from municipal organic wastes (MOWs), biodried products (BPs) are widely accepted as carbon-neutral and renewable energy resources. In this study, the pyrolytic products of BPs, i.e., syngas, tar and biochar, were comprehensively investigated, with a special focus on the synergistic effect of bulking agents (BAs) and the modification of biodegradation. Compared with the theoretical yields (31.12%–34.94%), the interactions of MOWs and BAs promoted biochar formation (34.65%–37.74%) during pyrolysis of raw materials (RMs). Biodegradation further enhanced the biochar yield (40.73%–49.50%) but limited the liquid yields (29.49%–38.04% vs. 39.75%–43.40%) during pyrolysis of BPs. Furthermore, biodegradation also enriched H2 in the syngas and promoted the formation of phenolic compounds (30.19%–47.83% vs. 11.08%–26.55%) in the tars during BP pyrolysis. In addition, the BP-biochar presented a higher porosity of mesopores, larger total volume (0.130–0.170 cm3/g) and pore size (4.15–4.77 nm); therefore, it had a higher methylene blue adsorption capacity than the RM-biochar (50.9–84.4 vs. 21.1–44.5 mg/g). These findings suggested that the interactive effect of BAs and the modification of biodegradation were effective in upgrading the pyrolytic products, including H2-rich syngas, phenolic-rich tar and mesoporous biochar. This study provides a promising strategy for the efficient utilization of MOWs by integrating biodrying and pyrolysis.