Effects of UV irradiation on humic acid removal by ozonation, Fenton and Fe 0/air treatment

Effects of UV irradiation on humic acid (HA) removal by Fe 0/air, ozonation and Fenton oxidation were investigated. The trihalomethane forming potential (THMFP) and toxicity of treated solutions were also evaluated. The experimental conditions were ozone of 21mgmin -1, H 2O 2 of 8×10 -4M, Fe 0 of 20gL -1, air flow of 5Lmin -1, and UVC of 9W. Results indicated that Fe 0/air rapidly removed HA color (>99%) and COD (90%) within 9min. 51-81% of color and 43-50% of COD were removed by ozonation and Fenton oxidation after 60min. 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 (114μgL -1) was much lower than those of Fenton- (226μgL -1) and ozonation-treated solutions (499μgL -1). Fe 0/air with UV irradiation obviously increased the THMFP of treated solution (502μgL -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.