Fate of 14C-acetyl sulfamethoxazole during the activated sludge process
2019
Geng, Chunnu | Zhuang, Yujia | Bergheaud, Valerie | Garnier, Patricia | Haudin, Claire-Sophie | The Ecological Technique and Engineering College ; Shanghai Institute of Technology (SIT) | Ecologie fonctionnelle et écotoxicologie des agroécosystèmes (ECOSYS) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | Université Paris-Saclay
Compared to antibiotic parent molecule, human metabolites are generally more polar and sometimes not less toxic in wastewater.However, most researches focus on the fate of parent molecule. Therefore, behaviors of human metabolites are little known.Moreover, though much has been done on the fate of antibiotics during activated sludge process, there are still some limitationsand gaps. In the present study, [Ring-14C] acetyl sulfamethoxazole (14C-Ac-SMX) was used to investigate the fate of humanmetabolite of SMX during activated sludge process at environmentally relevant concentration. At the end of 216 h, 3.1% of thespiked activity in the initial aqueous phase was mineralized, 50% was adsorbed onto the solid phase, and 36.5% still remained inthe aqueous phase, indicating that adsorption, not biodegradation, was the main dissipation pathway. In the existence of microbialactivities, accumulation into the solid phase was much higher, which was less bioavailable by chemical sequential extraction. Themultimedia kinetic model simultaneously depicted the fate of Ac-SMX in the gas, aqueous, and solid phases, and demonstratedthat microbially accelerated accumulation onto the solid phase was attributed to lower desorption rate from the solid phase to theaqueous phase, where adsorption rate was not the key factor. Therefore, Ac-SMX cannot be efficiently mineralized and remain inthe aqueous or the solid phases. The accumulation in the solid phase is less bioavailable and is hard to be desorbed in the existenceof microbial activities, and should not be easily degraded, and may lead to the development of antibiotic-resistant bacteria andgenes after discharge into the environment.
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