Degradation of selected triazole fungicides in constructed wetlands with application of biopreparation

Abstract

The purpose of this study was to determine the feasibility of using a constructed wetlands to degrade selected pesticides from wastewater and to evaluate their removal efficiency. In addition, a bio-preparation was used to increase the efficiency of the process, the rate of degradation and reduce the half-life of the compounds in wastewater. Pesticides from the triazole group of fungicides, which are commonly used in agriculture, were selected for the experiments. The study was conducted on a pilot scale, over 3 y, in two identical constructed wetlands systems supported and not supported by microorganisms. At the same time, in order to identify fungicides, an analytical method based on liquid chromatography-tandem mass spectrometry was optimized, enabling the determination of applied pesticides in wastewater with satisfactory sensitivity, accuracy and precision. The results obtained indicate that the applied constructed wetlands bed method for the treatment of pesticides from wastewater using Phragmites australis had a high average efficiency (88.1%). In the fungicide group, on day 2, the removal efficiency ranged from 21% to 25% in the constructed wet-lands bed, while with biopreparation support it ranged from 22% to 26.6%. The removal efficiency on day 14 was already 84%. The kinetics of fungicide decomposition in the constructed wetlands bed was determined on the basis of mathematical models and equations of the dynamics of pesticide disappearance in wastewater. The parameters of DT50 half-life of pesticides in wastewater and the parameters of theoretical time to reach the concentration level of 0.01 mg/L were determined. The microorganisms used increased pesticide removal efficiency by up to 7 d.