Degradation of veterinary antibiotics with biochar addition in the simulated liquid fertilization process.

Veterinary antibiotics (VAs) have been recognized as an emerging contaminant when they are released into the environment. The study evaluated VAs degradation using biochar with various particle sizes and dosage amounts in deionized water and simulated liquid fertilization process. Results showed that smaller particle sizes (<150 μm) and higher dosages (up to 1.0 %) of biochar enhanced the degradation efficiency (17.5-95.8 %), but excessive doses caused particle aggregation to reduce the sorption of VAs. Macrolides (MLs), which possess a non-planar lactone structure, exhibit relatively weak surface chemical interactions and therefore have a lower adsorption capacity than tetracyclines (TCs). In a simulated liquid fertilization process with 0.5 % dosage amount and fine biochar (<150 μm), aerobic conditions significantly improved VAs removal (aerobic with biochar: 93.5 % > aerobic: 89.7 % > anaerobic: 80.2 %). The main degradation mechanism of MLs could be the sorption onto biochar, and aeration would be the main reason for TCs' degradation. The results will help to understand the influence of biochar on the degradation of VAs and the potential feasibility of utilizing biochar during the liquid fertilization process.