Application of heterogeneous Fenton-like reaction with modified zeolite for removal of antibiotics, antibiotic-resistant bacteria, and antibiotic-resistant genes from swine farm wastewater

Abstract

The heterogeneous Fenton-like reaction with modified zeolite was introduced for the removal of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic-resistant genes (ARGs) to reduce environmental impact of the substance residues in swine farm effluent. The heterogeneous Fenton-like reaction with 100 g/L of the modified zeolite and 2 mM H₂O₂ could completely remove amoxicillin (AMX), tetracycline (TC), and tiamulin (TIA) in the swine farm effluent within 30 min. However, the antibiotic removal in the swine farm effluent was slower than in the ultrapure water. The heterogeneous Fenton-like reaction removed approximately 45–60% of dissolved organic carbon (DOC) and reduced the dissolved organic matter (DOM) sizes in the swine farm effluent. The large molecular size humic-like DOM co-existing in the swine farm effluent could probably decelerate the antibiotic removal via competitive adsorption and oxidation. To inactivate high-tolerant AMX-resistant E. coli, the heterogeneous Fenton-like reaction required 3-fold less exposure time than the H₂O₂ oxidation. No regrowth of the high-tolerant AMX-resistant E. coli was observed when the exposure time of the heterogeneous Fenton-like reaction was longer than 6 h. The heterogeneous Fenton-like reaction required the exposure time of 24 h to reduce the blaTEM genes, the AMX-resistant genes, of the high-tolerant AMX-resistant E. coli to the level of lower than the limit of detection. The results suggest that different reaction times are required for the removal of antibiotics (within 30 min), ARB (over 6 h), and ARGs (within 24 h). Furthermore, the heterogeneous Fenton-like reaction with the modified zeolite is a promising technology for sequential and efficient removal of antibiotics, ARB, and ARGs residues in swine farm effluent before being discharged into the environment.