Mechanisms of microorganisms and environmentally persistent free radicals in biochar/PMS degradation of antibiotics after the aging process of fermentation

The aging of pyrocarbon under the activity of microorganisms is a long and slow process. Microbial aging will affect the physicochemical properties of pyrocarbon and the removal of organic pollutants. Aging pyrocarbon through anaerobic fermentation more closely simulated the natural microbial processes. Anaerobic fermentation can be used to evaluate the degradation of organic pollutants by pyrocarbon/peroxymonosulfate. Pyrocarbon (HPBC), pyrocarbon + microplastics (HPBC + MPs), and MPs were added in fermentation system. The relative bacterial abundance confirmed that the addition of pyrocarbon and MPs provided carriers for bacterial growth, but it inhibited bacterial growth through biotoxicity. Environmentally persistent free radicals (EPFRs) were used to activate PMS to degrade antibiotics after aging. The concentration of EPFRs in the process of degradation of antibiotics by biochar/PMS first increased and then decreased, while the concentration of EPFRs in the natural environment continued to decrease. During the 30-day fermentation process, the degradation efficiency of antibiotics by biochar/PMS first decreased and then increased. After fermentation, the degradation efficiency on day 30 was 6.68%, 8.76%, and 7.24% higher than that on day 10. The aging process of anaerobic fermentation enhanced the biochar/PMS degradation of antibiotics, which suggested that pyrocarbon could be effectively used over the long term.