Simultaneous degradation of refractory organics, antibiotics and antibiotic resistance genes from landfill leachate concentrate by GAC/O3

Landfill leachate reverse osmosis concentrate (LLROC) contains a high amount of refractory organics, antibiotics and antibiotic resistance genes (ARGs), and the improper disposal of LLROC would pose a potential threat to local ecological environment. In this study, a granular activated carbon-catalyzed ozone (GAC/O3) system was used to simultaneous degrade multiple emerging contaminants from LLROC. The removal efficiency of refractory organics during GAC/O3 system were optimal when 4 g/L of GAC, 80 mg/min of O3, and initial pH of 7.65, and 55.7% of COD and 77.3% of UV254 were degraded within 30 min reaction. At the optimal conditions, the degradation efficiencies of ofloxacin, enoxacin, azithromycin, and tetracycline were 95.7%, 83.6%, 98.5%, and 100.0%, respectively. Moreover, approximate 80-100% of typical ARGs, including erm35, ermB, tetL, and dfrA1, were effectively removed. Hydroxyl radicals (HO center dot) was the dominant reactive oxygen species during GAC/O3 process, which played an important role in degrading refractory organics and antibiotics and inactivation ARGs. This finding suggests that GAC/O3 system is a promising technique for cleaning of multiple emerging contam-inants from LLROC.

Automated summary

In this study, a GAC/O3 system was used to simultaneously degrade multiple emerging contaminants from LLROC. The removal efficiency of refractory organics reached 55.7% and UV254 removal rate reached 77.3% under the optimal conditions. Ofloxacin, enoxacin, azithromycin, and tetracycline showed degradation efficiencies of 95.7%, 83.6%, 98.5%, and 100.0%, respectively.