The Acute Toxicity Change in the Microwave-enhanced Photolysis Degradation of Tetracycline

Abstract Antibiotic wastewater may generate more toxic by-products in the degradation process. It is of great significance to study the toxicity changes of the antibiotic intermediates for ecological safety of water environment. The microwave-enhanced photolysis process was set up and applied to the antibiotic tetracycline degradation. The luminescence inhibition rate of the luminescent bacteria was used as the evaluation index to investigate the acute toxicity changes of tetracycline intermediates. The toxicity changes with the degradation time and the effects of common water quality factors such as NO3 −, Cu2+ and humic acid on the acute toxicity of intermediates were studied. The results showed that nine intermediate products formed in the microwave-enhanced photolysis process. The acute toxicity of intermediates was generally reduced compared with tetracycline itself, but the luminescence inhibition rate of intermediates fluctuated with time. The luminescence inhibition rate of intermediates after 4 min of reaction was the highest, which meant the acute toxicity of intermediate products at 4 min was the largest. The presence of NO3 − (high concentration) and Cu2+ increased the acute toxicity of tetracycline intermediates, but the presence of humic acid could help reduce the acute toxicity of tetracycline degradation intermediates. This study provided theoretical basis and data reference for the practical application and ecological risk assessment of microwave-enhanced photolysis degradation of tetracycline.