Response of remediation performances and microbial communities of integrated vertical-flow constructed wetlands with different configurations after chronic exposure to pharmaceuticals and personal care products

Integrated vertical-flow constructed wetlands (IVCWs) received increasing concern on pollutant elimination with high cost-effectiveness, even for emerging contaminants such as pharmaceuticals and personal care products (PPCPs). However, it will be beneficial for the further reduction of input costs if the correlation between different construction strategies and corresponding removal performance can be clearly elucidated. In this study, three IVCWs with different configurations were constructed to clarify the effect of artificial aeration and planting on pollutant removal after chronic exposure to PPCPs. The CW-A with artificial aeration and planting exhibited superior nitrogen removal performance (>90 %) over the other two systems, though along with increased input expenses. All types IVCWs showed satisfying removal performance of CODCr, TP, MEA, and 2-php after maturity of CWs. The participation of planting Canna indica improved the elimination of sulfamethoxazole (SMX), evidenced by a higher removal efficiency of 92.42 % in CW-A and 90.86 % in CW-B, compared to 69.58 % in CW-C. No obvious differences were observed in all groups for removing mefenamic acid (MEA) and 2-phenylphenol (2-php) with a satisfying removal rate of over 90 %. Ammonia-oxidizing bacteria (AOB) were limited after exposure in all IVCWs while denitrifying bacteria still existed in high abundance. Notably, results showed that the main pathway of PPCPs removal was biodegradation according to the mass balance. Findings from this work could provide informative references for the construction and maintenance of IVCWs with minimized expenses in practical applications while preserving excellent removal efficiencies of nitrogen and PPCPs.