Elucidating tetracycline degradation in a coupled system of photocatalysis combined with Bacillus cereus

Tetracycline (TC) causes environmental problems, so its effective degradation technology has attracted wide attention. A coupled system combined photocatalysis with Bacillus cereus (CS) was adopted for TC degradation in this study to make up the defects of the separate photocatalytic system (SPS) and the separate microbial system (SMS). The results showed that the CS outperformed the SPS or SMS, with the removal rate of TC and total organic carbon (TOC) reaching 82.1 % and 51.6 %, respectively. Moreover, photoelectrons in the CS were significantly higher compared with the SPS, and the hydrogen peroxide concentration, O2− and soluble iron content were slightly higher, but OH content was lower, indicating that photoelectrons played a primary role in TC degradation. The CS had stronger electron transport activity compared with the SMS, indicating that the presence of photocatalyst was conducive to the degradation of TC by Bacillus cereus. The lower cytochrome C content in the CS revealed that photocatalysis caused a certain degree of damage to Bacillus cereus, but it still could hinder the recombination of photoelectrons and holes, which enhanced the degradation efficiency. Finally, the degradation pathway of TC was inferred by intermediate products, and the result indicated TC was effectively degraded under the combined action of photocatalysis and microorganisms. The study provides valuable insights for degradation of antibiotics.