Effects of UV irradiation on humic acid removal by ozonation, Fenton and Fe0/air treatment: THMFP and biotoxicity evaluation

Effects of UV irradiation on humic acid (HA) removal by Fe-0/air, zonation and Fenton oxidation were investigated. The trihalomethane forming potential (THMFP) and toxicity of treated solutions were also evaluated. The experimental conditions were ozone of 21 mg min(-1), H2O2 of 8 x 10(-4) M, Fe of 20 g L-1, air flow of 5 L min(-1), and UVC of 9W. Results indicated that Fe-0/air rapidly removed HA color (>99%) and COD (90%) within 9 min. 51-81% of color and 43-50% of COD were removed by ozonation and Fenton oxidation after 60 min. Both UV enhanced ozone and Fenton oxidation removed HA, but the Fe-0/air process did not. Spectrum results showed all processes effectively diminished UV-vis spectra, except for ozonation. The THMFP of Fe-0/air-treated solution (114 mu g L-1) was much lower than those of Fenton- (226 mu g L-1) and ozonation-treated solutions (499 mu gL(-1)). Fe-0/air with UV irradiation obviously increased the THMFP of treated solution (502 L-1). The toxicity results obtained from Vibrio fischeri light inhibition test indicated that the toxicity of Fe-0/air-treated solution (5%) was much lower than that of ozonation- (33%) and Fenton-treated solutions (31%). Chlorination increased the solution toxicity. The correlation between biotoxicity and chloroform in the chlorinated solution was insignificant. (C) 2011 Elsevier B.V. All rights reserved.