Atenolol removal in microcosm constructed wetlands

Abstract

Microcosm constructed wetland systems established with a matrix of light expanded clay aggregates (LECA) and Typha spp. or Phragmites australis were used to evaluate their ability to remove atenolol from wastewater. Combined with an efficient SPE concentration step, the use of HPLC-DAD yielded an analytical method for atenolol quantification with very low LOQ (9 ng mL−1) and high reproducibility (RSD < 4%). Overall removal efficiencies of 92.5% and 94.5% were achieved after a retention time of only 4 days with the microcosm systems planted with Phragmites australis and Typha spp., respectively. The removal kinetics was characterised by an initial fast step (removal of about 75% after just 24 h) which is mainly attributable to adsorption on the LECA matrix. Atenolol removal in LECA beds continues to increase in a steady pace up to the end of the assay (8 days) being nevertheless about 5–10% lower than those observed in the planted beds after the first 4 days. For the retention time of 4 days most of the atenolol is removed by the LECA matrix but an additional 12–14% of the overall removal efficiency can be attributed to the Typha and Phragmites plants, which is in agreement with other published reports. Despite the fact that further tests using larger-scale flowing systems are required to evaluate fully the atenolol behaviour in constructed wetlands, this study points to the possible application of these low-cost wastewater treatment systems to treat atenolol contaminated wastewater.