Enhancement of Bacillus subtilis inactivated Microcystis aeruginosa by shaped biochar: Performance and mechanism study

Finding a cost-effective solution to harmful algal blooms (HABs) is a global priority. While the microbial method is seen as a promising, eco-friendly and easy-to-use algae removal technology, it is limited by low efficiency and long treatment times. In the development of functional microorganisms, environmentally functional materials (e.g., clay minerals, carbon materials) have demonstrated potential to enhance microbial activity, yet little research exists on microbial Cyanobacteria removal. This study developed a carbon-based functional material system (granular activated carbon and biochar) to enhance functional microorganisms for dissolving Microcystis aeruginosa and explored the algal lysis mechanism of the biochar-Bacillus system with optimal performance. Under optimal conditions, over 92 % of chlorophyll a was removed in 8 days, with lysis efficiency retaining 85 % after 4 cycles. Results indicated algal removal by Bacillus involve direct removal and indirect inactivation. Biochar's porous structure provides adsorption sites for Bacillus, algal cells, and their secretions, fostering efficient interfacial reactions and improving removal efficiency. Additionally, biochar stabilizes the system, promotes algal flocculation, and facilitates electron transfer.