H2O2/UV-Coxidation of potential endocrine disrupting compounds: a case study with dimethyl phthalate

Abstract

This paper discusses the feasibility of the ultraviolet radiation-hydrogen peroxide (H(2)O(2)/UV-C) process as an advanced oxidation process (AOP) in the treatment of endocrine disrupting compounds (EDC). Dimethyl phthalate (DMP) was chosen as the model compound owing to its classification as an EDC. Experiments have been conducted at various pH values (3.5, 6.0 and 9.0) and initial H(2)O(2) concentrations (0-60 mM) in a batch reactor equipped with a low-pressure mercury UV-C lamp in order to evaluate the optimal operation conditions of the H(2)O(2)/UV-C process. The most effective pH value for the degradation of DMP by H(2)O(2)/UV-C treatment was found as 6.0. DMP abatement increased with increasing H(2)O(2) concentrations from 5 to 30 mM. Further increase in initial H(2)O(2) concentration, however, reduced both the rate and extent of DMP removal as well as chemical oxygen demand (COD) and total organic carbon (TOC) removals. A simple kinetic model was proposed for DMP, COD and TOC abatements confirmed pseudo-first-order reaction. The electrical energy per order (EE/O) values for DMP oxidation and TOC mineralization were calculated as 3.3 and 19 kWh m(-3) order(-1) respectively for the optimum treatment conditions (H(2)O(2,o) = 30 mM, pH(o) = 6.0, DMP(o)= 100 mg L(-1)). Inhibition of oxygen uptake rate by activated sludge (ISO 8192) was evaluated as a tool for assessing the acute toxicity of untreated and H(2)O(2)/UV-C treated DMP. According to the results obtained in this work, the use of the H(2)O(2)/UV-C process is recommended to achieve a complete DMP oxidation and high mineralization degree of aqueous solution of DMP.