Intensified pharmaceutical and personal care products removal in an electrolysis-integrated tidal flow constructed wetland

Abstract

To improve the removal of pharmaceutical and personal care products (PPCPs) from contaminated water, a novel electrolysis-integrated tidal flow constructed wetland system (E-TFCW) was developed. E-TFCWs have the highest removal efficiency for the four investigated PPCPs when the electrodes are arranged at the bottom of the E-TFCWs. The removal efficiency of four PPCPs increases from 4.41% to 11.71% to 28.83%-68.32% when using electrolysis combined with tidal flow constructed wetlands. The synergy effect for the degradation of PPCPs between electrolysis and constructed wetlands on the degradation of PPCPs in E-TFCWs were significant (enhancement factor > 1), while the removal efficiency of PPCPs after the electrolysis (10 h, accounting for 14.98–44.41%) is higher than that before electrolysis (10 h, accounting for 9.62–27.14%) and electrolysis process (4 h) accounting for 42.81%-68.47%. Electrolysis can enhance the removal of PPCPs through direct oxidation. Moreover, the increase in intermediate oxidation compounds in the E-TFCWs may imply the enhanced biodegradability of PPCPs during the electrolysis process since the by-products of PPCPs were identified. The contents of Thermomonas, Microbacterium, Cloacibacterium and Acidovorax at the bottom of the E-TFCWs were significantly higher than those of other bacteria, which contributed to the removal of PPCPs. Electrolysis can enhance the biodegradability of PPCPs and the formation of anoxic/aerobic conditions for the growth of predominant bacteria, which contributes to the degradation of PPCPs in the E-TFCWs. The results illustrate that electrolysis-integrated tidal flow constructed wetlands are an effective technology for the removal of PPCPs.