Bioconversion of citrus peel wastes into bioflocculants and their application in the removal of microcystins.

In this study, the mechanism for converting citrus peel wastes (CPW) into bioflocculants using Alcaligenes faecalis subsp. phenolicus ZY-16 was analysed. The results demonstrated that the ZY-16 strain could produce various lignocellulolytic enzymes, containing cellulase, hemicellulase, pectinase, protease, and ligninase, enhancing the hydrolysis of citrus peel wastes. Molecular distillation removes antimicrobial limonene, which could inhibit bioflocculant production. The optimal fermentation conditions with the highest bioflocculant yield (3.49 g/L) were 38.79 g/L of CPW, 35.54 °C, and pH 4.48. Furthermore, the bioflocculant was used to eliminate microcystins for the first time, and the highest removal efficiency (90.05%) was achieved at a pH of 3.0, after 800 mg/L of bioflocculant was added into the microcystins solution (10 mg/L) for 60 min. Therefore, this paper demonstrated that CPW could be a cost-effective feedstock for the production of bioflocculants, which have potential application in microcystin removal.