Removal of chlortetracycline from water by immobilized Bacillus subtilis on honeysuckle residue-derived biochar

摘要

Biochar-immobilized microorganism technology is an effective way to remove antibiotic contamination in aqueous solutions. In this study, the effect and mechanism of immobilization of Bacillus subtilis by honeysuckle residue-derived biochar for the removal of chlortetracycline (CTC) were investigated using corn straw biochar as a comparison. The biochar's structural characteristics and properties were determined using scanning electron microscopy, X-ray diffractometer, Fourier-transform infrared spectrometer, specific surface area, and pore size analyzer. It was found that honeysuckle residue-derived biochar had a well-developed pore structure, which provided adequate living space for microorganisms. The removal rate of CTC (50 mg/L) by honeysuckle residue biochar-microbial complex (HBCM) was 15.31% higher than that of corn straw biochar-microbial complex, indicating that HBCM was an excellent carrier. The mechanism of CTC removal by HBCM was a synergistic effect of biochar adsorption and microbial degradation. The removal process of HBCM material was carried out for 3 days at an optimum substrate concentration of 50 mg/L, an ambient temperature of 35 degrees C, a solution pH of 7, and the addition of 5 g/L complexes, achieving a removal rate of 78.35%. In addition, the complex possessed high storage stability and could be reused three times continuously and efficiently. This study provides a method for preparing an efficient biochar-microbial complex using Chinese medicine residue waste substrate, which provides a new idea for removing CTC from water.