Removal of selected antibiotics and antiretroviral drugs during post-treatment of municipal wastewater with UV, UV/chlorine and UV/hydrogen peroxide

Active pharmaceutical ingredients (APIs) are only partially removed by convectional wastewater treatment plants. This study aimed at assessing the post-treatment degradation of selected antibiotics and antiretroviral drugs by direct UV photolysis and advanced oxidation processes (UV/H(2)O(2)and UV/Cl-2) using low-pressure mercury lamp. The rate of degradation largely followed pseudo first-order reaction kinetics. Amongst the six studied APIs, sulfamethoxazole, ciprofloxacin and zidovudine were readily degraded by more than 90% using direct UV photolysis. Addition of Cl(2)and H(2)O(2)to the UV process led to an increase in the rate of degradation for all the compounds. The effectiveness UV/Cl(2)process was affected to a greater extent by the background effluent organic matter. This implies that higher electrical energy and oxidant would be required in the UV/Cl(2)process relative to UV/H(2)O(2)process. Generally, electrical energy required to remove 90% of the target compounds increased in the order UV/H2O2< UV/Cl-2 < UV processes.