FERRIOXALATE-MEDIATED PHOTODEGRADATION OF ORGANIC POLLUTANTS IN CONTAMINATED WATER

The UV-visible photolysis of ferrioxalate in the presence of hydrogen peroxide (the UV-vis/ferrioxalate/H2O2 process) is investigated for th e treatment of contaminated groundwater and industrial wastewater. Thi s process generates the hydroxyl radical, which is a strong oxidant an d reacts rapidly with most organic compounds present in solution. Tap water spiked with various organic pollutants, a process water containi ng chlorobenzene, a tank-bottom water containing a mixture of benzene, toluene and xylenes (BTX), a wastewater containing 1,4-dioxane and an other wastewater containing methanol, formaldehyde and formic acid wer e treated with the UV-vis/ferrioxalate/H2O2 process and the efficiency compared with alternative oxidation processes, including the UV/H2O2 and UV-vis/Fe(II)/H2O2 (UV-Fenton) processes. The destruction of speci fic compounds and group parameters, such as TOC and BOD, were used to examine the relative energy efficiencies of the alternative processes. The data indicate that in nearly all cases, the new UV-vis/ferrioxala te/H2O2 process has a much higher efficiency (by a factor of about 3 t o 30) than does either the UV-vis/Fe(II)/H2O2 process or the UV/H2O2 p rocess. It is concluded that this new process is very efficient and us eful for the treatment of moderate to highly contaminated waters. (C) 1997 Elsevier Science Ltd.