Characterization and Performance in Adsorption of Bacillus megaterium of Biochar from Three Edible Fungus Spent Artificial Logs

Purpose To investigate the physicochemical properties of biochars made from different edible fungus spent artificial logs and their ability to adsorb Bacillus megaterium, providing a basis for the high-value utilization of edible fungus spent artificial logs.

Methods Three types of edible fungus (Flammulina velutipes, Hypsizygus marmoreus, and Tremella fuciformis) spent artificial logs were used as raw materials, six types of biochars were produced by pyrolysis for two hours at 700 ℃ under CO₂ or N₂ atmosphere. The biochars were characterized for their physicochemical properties, and the adsorption performance of biochars for B. megaterium was studied through an orthogonal experiment.

Results All six types of biochars were alkaline, with yields ranging from 34% to 42%, ash content ranging from 10% and 59%, and carbon content ranging from 44% and 72%. The biochars had high aromaticity and functional groups beneficial to microbial adsorption. The average pore size ranged from 1.92 to 4.94 nm, and the pore volume ranged from 0.012 to 0.099 cm³/g. Biochars obtained under CO₂ atmosphere had a higher specific surface area and pore volume compared to that obtained under N₂ atmosphere. The optimal combination of temperature, fungal suspension-to-biochar ratio, and adsorption time for adsorption of B. megaterium by the biochars derived from CO₂ atmosphere were 25 ℃, 10∶1, and 24 hours, respectively, with adsorption rates above 93%.

Conclusion The biochar made from F. velutipes spent artificial log under CO₂ atmosphere have the best adsorption effect, with an adsorption rate of 95.55%, demonstrating its potential as a carrier and for further applications. The results provide a new approach for the resource utilization and high-value application of edible fungus spent artificial logs.