Chiang Mai Journal of Science

Cigarette butts (CB), which amount to approximately 800,000 tons annually and are commonly discarded as toxic waste, pose a serious threat to the environment. Despite their abundance, CB are often overlooked and were previously mistakenly assumed to be biodegradable, resulting in their underutilization for resource recovery. This study evaluated the feasibility of using CB waste as a potential alternative substrate for oyster mushroom cultivation by systematically examining the effects of varying CB addition ratios (0%, 10%, 20%, and 30%) on mycelial growth rate, fruiting body yield, biological efficiency, and moisture content. The results showed that CB addition significantly affected total dry weight yield (p < 0.05, η² = 0.507) and moisture content (p < 0.05, η² = 0.490), but had no significant effect on biological efficiency (p > 0.05, η² = 0.042). The cultivation substrate with 10% CB addition achieved a mycelial growth rate (3.04 cm/day) that was 86.5% higher than that of the control (1.63 cm/day), and a total dry weight yield (8.53 g/bag) that was slightly higher than the control (7.94 g/bag). In contrast, addition ratios ≥20% inhibited mycelial growth, reduced dry weight yield, and resulted in abnormally high moisture content in fruiting bodies, likely due to physiological stress induced by heavy metal ions present in CB. Maintaining the CB addition ratio at 10% balances waste resource utilization with optimal mushroom production, providing a theoretical basis and key bioprocess parameters for developing a circular bioeconomy model. Notably, while this study establishes the technical viability, we underscore that translating this model into actual food/feed industrial practice will require mandatory pre-market safety evaluations, particularly regarding heavy metal bioaccumulation and mycotoxin contamination.