2022 Volume 58 Issue 4 Pages 137-148
Synthetic landfill leachate containing phenolic compounds (phenol and bisphenol A) and heavy metals (chromium (Cr) and manganese (Mn)) at 30 mg/L each were treated using column-type two-stage constructed wetland (CW) systems which were compiled with gravel and activated carbon as the substrate. Four types of CWs with and without planting common reeds and with two feeding modes (continuous and batch feeding modes) were operated for 96 d with varying hydraulic retention times (HRTs) of 5, 3, 2, and 1 d. Longer HRT (i.e., 5 d) was required for efficient removal of NH4－N, Cr, and Mn. The removal of NH4－N was higher in continuous-feed CWs, whereas batch-feed CWs were effective in the removal of heavy metals. Chemical oxygen demand and phenol could be removed efficiently, irrespective of vegetation, feeding mode, and HRT, which indicated the importance of substrate selection. By contrast, the adsorption onto the substrate as well as aerobic degradation by microorganisms in the presence of sufficient dissolved oxygen were likely significant on the removal of BPA. This study demonstrated the effectiveness of column-type two-stage CWs, and the distinct impact of feeding mode and HRT in the treatment of pollutants with different physical and chemical properties.
