Removal of six phthalic acid esters (PAEs) from domestic sewage by constructed wetlands

• Most PAEs could be efficiently removed by specific constructed wetlands (CWs).
• Flow types and HLRs were the most important influencing factor.
• DO significantly impacted PAEs removal.
• Biodegradation and adsorption were the two major processes for PAEs removal by CWs.

This study assessed the influence of different treatment configurations on the removal of six types of phthalic acid esters (PAEs) (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzylphthalate (BBP), di-n-octyl phthalate (DOP) and bis (2-ethyl) hexylphthalate (DEHP)) from domestic wastewater in twelve pilot-scale constructed wetlands (CWs). Removal methods were investigated using orthogonal array testing with the following parameters of interest: four different water flow types, three substrates, two types of live plants, and three hydraulic loading rates (HLRs). Results showed that PAE removal efficiencies differed based on chemical properties. Water flow type in the wetland was the most important factor in eliminating PAEs; downward vertical flow wetlands were most effective. The removal of high hydrophobicity DEHP and DOP was significantly impacted by substrate type; gravel systems were better than vesuvianite and zeolite systems. In addition, HLRs were important factors in reducing PAEs; the optimal HLR is 0.125–0.25 m/day, allowing PAEs to come into contact with substrate biofilm. Study results suggest that microbiological activity and adsorption were the most prevalent removal route for PAEs in constructed wetlands.