The goal of this study is to investigate the occurrence and removal of emerging organic contaminants (EOCs) during wastewater treatment processes and understand the role of enhanced nitrification treatment in removing EOCs. Influent and effluent of each treatment step at two local wastewater treatment plants (WWTPs) were analyzed by high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS). A suspect screening method was applied with a comprehensive self-compiled suspect list. The list is comprised of 1225 EOCs in 5 categories: pharmaceuticals, personal care products, pesticides, industrial chemicals, and metabolites. A total of 292-341 suspect hits were retrieved from HRMS full scan. Structures of 56 out of 86 selected suspect hits were further validated with reference standards or according to MS2 fragmentation profiles in database library. Estimated influent concentrations of EOCs in two WWTPs varied in a large range, from several ng/L to less than a hundred µg/L. Paracetamol, caffeine, 1,2,3-benzotriazole, DEET, gabapentin, metformin, N4-acetylsulfamethoxazole, atenolol acid, triethanolamine, triethyl phosphate and valsartan were dominant with influent concentrations over 2 µg/L. Results also revealed that many EOCs, such as fexofenadine, citalopram, flecainide, had low removal efficiencies. Seasonal effects were larger than location influence on EOC removal. The secondary biological treatment played the most crucial role in EOCs removal, whereas other steps including the enhanced nitrification step exhibited substantial removal for a small number of EOC suspects. Notably, back-transformation between some parent EOCs and their metabolites was also observed. This study provides systematic information on occurrence and removal of EOCs in WWTPs, which can help predict environmental occurrence of some persistent EOCs, as well as guide advanced treatment of EOC residues.

Occurrence and fate of emerging organic contaminants in wastewater treatment processes with an enhanced nitrification step

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.