Identification and Mitigation of By-Products Formed During an Advance Oxidation of Emerging Contaminants: Example of Pharmaceutical Sulfamethoxazole

Abstract

A variety of adverse effects on environment and public health have been linked to the presence of emerging contaminants (ECs) in surface waters. Sulfamethoxazole (SMX) is one of the ECs that traces (in ppb to ppt) have been found in surface water due to its persistence in environment and its insufficient removal at the wastewater treatment plants (WWTPs). Advanced oxidation processes (AOPs), such as UV/H2O2 system, have been recognized as an effective technology to remove recalcitrant ECs. However, there have been very few studies, which followed the formation of AOP by-products and there is still much uncertainty over AOP by-products’ identification. In current study, the SMX removal by UV/H2O2 AOP was investigated including identification, controlling and mitigation of SMX by-products. The results showed 99.99% removal of SMX in deionized (DI) water within 30 min. Major SMX by-products, identified by LC-MS-MS analysis, revealed longer lifetime and higher stability than SMX parent ion removed from the water matrix. The influence of technological parameters (oxidant’s dose, exposure time, pH and aeration rate) on the SMX removal and mitigation of BPs were imminent, in which the maximum SMX removal was achieved, while BPs were controlled and minimized in optimal conditions.