Comparison of mcpa (4-Chloro-2-methyphenoxy acetic acid) removal in two types of constructed wetlands

Abstract

In this paper, the treatment performance of laboratory-scale free surface flow and subsurface flow constructed wetlands contaminated with MCPA was discussed. The free surface flow constructed wetland was planted with Lemna minor L. The average MCPA removal efficiencies for the planted and unplanted reactors were 32.05 and 58.11%, respectively. The subsurface flow constructed wetland was planted with Phragmites australis (Cav.) Trin. Ex. Steudel, and light expanded clay aggregates (Leca) were used as bed's substrates. The average MCPA removal efficiencies for the planted and unplanted reactors were 80.64 and 97.87%, respectively. The obtained results indicated that the subsurface flow constructed wetland type was of good performance in removal of synthetic wastewaters from related chemical structures of pesticides. Leca has a large sorption capacity for the MCPA. Moreover, it has been thought to be eligible for use as support matrix in constructed wetland systems. In addition, two models (Langmuir and Freundlich) were used for modeling of the pesticide adsorption of Leca, which was better explained by the Langmuir isotherm model.