Wetland plant-derived biochar enhances the diclofenac treatment performance in vertical subsurface flow constructed...

Diclofenac (DFC) is a pharmacologically active compound frequently detected in various receiving waters. To improve the efficiency of constructed wetlands in removing DFC, biochar (BC) is added as a substrate. The study mainly involved the effect of adding wetland plant-derived BC to vertical subsurface flow constructed wetlands (VSF-CWs) on the DFC removal process. In addition, the study discussed the effects of the initial DFC concentration (0.05-1.00 mg L^-1), pH (5.5-8.5), and hydraulic retention times (HRTs, 1-7 d) on the removal process and fluctuations in the microbial community. Preliminary results of the study showed optimal removal (>90%) achieved at an initial DFC concentration of 0.75-1 mg L^-1, a pH of 6.5-7.5, and an HRT of 7 d. Moreover, no significant effects on the removal efficiency of conventional water quality parameters were observed. Non-metric multidimensional scaling results revealed a reshaped community structure, which was altered by the initial DFC concentration. DFC concentration is a key factor in the variation of microbial communities and controls the quantitative evolution of the species in experimental units. Therefore, the addition of BC to CWs effectively enhanced the removal efficiency of DFC and provided a viable and effective improvement of the CWs.