Decomposition of 1,4-dioxane by photo-Fenton oxidation coupled with activated sludge in a polyester manufacturing process

摘要

The cyclic ether 1,4-dioxane is a synthetic industrial chemical that is used as a solvent innproducing paints and lacquers. The EPA and the International Agency for Research onnCancer(IARC) classified 1,4-dioxane as a GROUP B2(probable human) carcinogen. 1,4-dioxane isnalso produced as a by-product during the manufacture of polyester. In this research, a polyesternmanufacturing company (i.e. K Co.) in Gumi, Korea was investigated regarding the release of highnconcentrations of 1,4-dioxane (about 600 mg/L) and whether treatment prior to release shouldnoccur to meet with the level of the regulation standard (e.g., 5 mg/L in 2010). A 10 ton/day pilotscalentreatment system using photo-Fenton oxidation was able to remove approximately 90% ofn1,4-dioxane under the conditions that concentrations of 2800ppm H2O2 and 1,400ppm FeSO4nwere maintained along with 10 UV-C lamps (240mW/cm2) installed and operated continuouslynduring aeration. However, the effluent concentration of 1,4-dioxane was still high at aboutn60 mg/L where TOC concentration in the effluent had been moreover increased due tondecomposed products such as aldehydes and organic acids. Thus, further investigation is needednto see whether the bench scale (reactor volume, 8.9 L) of activated sludge could facilitate thendecomposition of 1,4-dioxane and their by-products (i.e., TOC). As a result, 1,4-dioxane in theneffluent has been decreased as low as 0.5 mg/L. The optimal conditions for the activated sludgenprocess that were obtained are as follows: DO, 3-3.5 mg/L; HRT, 24 h; SRT 15 d; MLSS, 3,000 mg/L.nConsequently, photo-Fenton oxidation coupled with activated sludge can make it possible tonefficiently decompose 1,4-dioxane to keep up with that of the regulation standard.