Comparison of pre-oxidation between O-3 and O-3/H2O2 for subsequent managed aquifer recharge using laboratory-scale columns

Abstract

A hybrid process of managed aquifer recharge with pre-oxidation was investigated as part of a multiple-barrier approach for safe water production. This study evaluated O-3 and O-3/H2O3 for the pre-oxidation of urban surface water prior to managed aquifer recharge (MAR) and compared their effectiveness with respect to trace organic contaminants (TrOCs), biostability, and trihalomethane formation potential. The combination of pre-oxidation and MAR was performed using long-term column studies, and the results confirmed the removal of 64 and 56% dissolved organic carbon by using O-3 and O-3/H2O2, respectively. MAR combined with O-3 and O-3/H2O2 achieved > 50% removal of dissolved organic carbon with the first 5 days of residence time. 03 alone showed better performance in alleviating trihalomethane formation potential during chlorination compared to using O-3/H2O2. The pre-oxidation of urban surface water was effective in attenuating selected TrOCs (35 - > 99% removal), and subsequent MAR achieved > 99% removal of selected TrOCs within the first 5 days, regardless of pretreatment methods examined in this study. The results of this study provide an understanding of the effects of O-3 and O-3/H2O2 as pre-oxidation processes on urban surface water prior to MAR, as well as the resulting impact on MAR.