Anaerobic co-digestion of tobacco processing residue: Multi-step approach for process optimization, key syntrophic microbiome identification, and techno-economic analysis

This study evaluated the improved applicability of tobacco dust mixture (TDX), a residue generated during tobacco processing, as a substrate for anaerobic digestion (AD). The biochemical methane potential (BMP) test demonstrated that TDX alone produced 201.3 mL CH4/g volatile solids (VS), while food waste (FW) and sludge (SL) exhibited CH4 yields of 568.9 and 91.4 mL CH4/g VS, respectively. Additionally, the inhibition effect on biogas production due to nicotine content was found to be negligible below the threshold of 1 g nicotine/L. Co-digestion of TDX with FW and SL resulted in a synergistic effect, mainly when FW constituted at least 25 % of the total VS. The microbial analysis revealed microbes, such as Syntrophomonas and Sedimentibacter, that played key roles in AD of TDX. A techno-economic analysis assessed the feasibility of different AD process configurations under three primary objectives: waste removal, energy production, and digester volume optimization. Results indicated that prioritizing energy production reduced operational costs by up to 28 %, whereas strategies emphasizing waste removal and minimized digester footprint led to 15 % and 20 % reductions, respectively. In conclusion, TDX's co-digestion with FW enhances CH4 production efficiency and offers a practical and economically viable strategy for sustainable waste management.