Biological and chemical phosphorus solubilization from pyrolytical biochar in aqueous solution

Biochar, a massive byproduct of biomass pyrolysis during biofuel generation, is a potential P source for the mitigation of P depletion. However, the chemical and biological effect of the release of P from biochar is still unclear. In this study, two types of Lysinibacillus strains (Lysinibacillussphaericus D-8 and Lysinibacillus fusiformis A-5) were separated from a sediment and their P-solubilizing characteristics to biochar was first reported. Compared with the bacterial mixture W-1 obtained from a bioreactor, the introduction of A-5 and D-8 significantly improved P solubilization. The release of P from biochar by A-5 and D-8 reached 54% and 47%, respectively, which is comparable to that under rigorous chemical conditions. SEM images and XPS spectra demonstrated that the physicochemical properties of the biochar surface have changed in the process which may be caused by the activities of the microbes.