Industrial wastewater advanced oxidation. Part 1. UV radiation in the presence and absence of hydrogen peroxide

The oxidation of two wastewaters collected from distillery and tomato processing plants with UV radiation (254 nm) alone and combined with hydrogen peroxide has been investigated. Distillery wastewaters are refractory to UV radiation but the presence of hydrogen peroxide leads to different COD reductions which indicates that the process is mainly due to the action of radicals. Tomato wastewaters, on the other hand, show a higher reactivity even with UV radiation alone. The quantum yield for tomato wastewaters with an initial COD of 930 mg O2l−1 was found to be 0.7 mol O2 photon−1 and decreased with reaction time. The combined effect of UV radiation and hydrogen peroxide at a 0.01 M concentration on tomato wastewaters leads to about 25% COD reduction while TOC was unchanged. The contribution of radical reactions in this process was higher than 60%.