Combined coagulation/decantation-ozone/hydrogen peroxide-biological aerated filter process for advanced treatment of bio-treated leachate from Chinese herbal medicine residue

Abstract

To reach discharge limit, further treatment of bio-treated leachate from Chinese herbal medicine residue (BLCHMR) was very imperative. In this study, performance of combined coagulation/decantation-ozone/hydrogen peroxide (O3/H2O2)-biological aerated filter (BAF) technology used to further treat BLCHMR was investigated with pilot-scale experiment. Under optimal conditions, the COD (40–44 mg/L) and color (13–17 time) in treated BLCHMR indicated that combined process can efficiently treat BLCHMR. O3/H2O2 had good performance not only in mineralization and decomposing of organic matter but also in decolorization of BLCHMR. For dissolved organic matter (DOM), O3/H2O2 reacted with non-biodegradable fraction preferentially and oxidized different molecular weight (MW) fractions equally. O3/H2O2-BAF generated more higher MW DOM (namely F2 fraction) than BAF alone. Meanwhile, O3/H2O2 mainly influenced the amount and biodegradability on DOM but not the removal rate on DOM. Accordingly, the helpful influence on O3/H2O2 perhaps can be owed to the generalized influence on DOM but not the specific influence on improved biodegradability. Finally, inspiring (namely very low) cost (respectively, 0.3419 $/per ton bio-treated leachate and 0.5766 $/Kg COD removed) was achieved in the combined process.