Adsorption of metolachlor on woodchips

Adsorption of metolachlor on woodchips

Abstrakt

Denitrifying woodchip bioreactors (DWBs) are utilized for reducing nitrate levels in agricultural runoffs. They typically take the form of excavations filled with woodchips. Other substances, including pesticides and their metabolites, were also identified at the inlet to the DWBs. Their decomposition time often reaches tens of days. Extending their retention time through adsorption on woodchips could foster their biodegradation. The hydraulic retention time in DWBs can be up to 24 hours. Therefore, a 24-hour test was designed that allows to determine the adsorption rate of pesticides onto the bioreactor filling. The adsorption test was carried out with metolachlor as a model compound in 16 two-liter glass bottles. 48 hours before the start of the test, 30 g of poplar shavings and 2 l of liquid medium containing 15 mg NO3-N/l were added to each bottle. The bottles were bubbled with argon, closed, and incubated at a temperature of 15 °C. At the start of the experiment, a mixture containing metolachlor and its 4 metabolites was added to each bottle, so that the initial concentration of metolachlor was 0.25 µg.L-1, and its metabolites 0.5 µg.L-1. The pH, dissolved oxygen, NO3-N, and the concentration of pesticide substances were measured. Every 6 hours, the adsorption process was terminated in 4 bottles. The previously mentioned parameters plus COD and NO2-N concentrations were determined. During the test period, denitrifying conditions were sustained in the bottles, as evidenced by the low oxygen concentration (

Denitrifying woodchip bioreactors (DWBs) are utilized for reducing nitrate levels in agricultural runoffs. They typically take the form of excavations filled with woodchips. Other substances, including pesticides and their metabolites, were also identified at the inlet to the DWBs. Their decomposition time often reaches tens of days. Extending their retention time through adsorption on woodchips could foster their biodegradation. The hydraulic retention time in DWBs can be up to 24 hours. Therefore, a 24-hour test was designed that allows to determine the adsorption rate of pesticides onto the bioreactor filling. The adsorption test was carried out with metolachlor as a model compound in 16 two-liter glass bottles. 48 hours before the start of the test, 30 g of poplar shavings and 2 l of liquid medium containing 15 mg NO3-N/l were added to each bottle. The bottles were bubbled with argon, closed, and incubated at a temperature of 15 °C. At the start of the experiment, a mixture containing metolachlor and its 4 metabolites was added to each bottle, so that the initial concentration of metolachlor was 0.25 µg.L-1, and its metabolites 0.5 µg.L-1. The pH, dissolved oxygen, NO3-N, and the concentration of pesticide substances were measured. Every 6 hours, the adsorption process was terminated in 4 bottles. The previously mentioned parameters plus COD and NO2-N concentrations were determined. During the test period, denitrifying conditions were sustained in the bottles, as evidenced by the low oxygen concentration (

denitrifying woodchip bioreactor, denitrification, pesticide, laboratory adsorption test

denitrifying woodchip bioreactor, denitrification, pesticide, laboratory adsorption test

NOVOTNÁ, K.; HRICH, K.; MALÁ, J.

03.11.2025

University of Novi Sad, Faculty of Technology Novi Sad, Bulevar cara Lazara 1, Novi Sad, Serbia

Novi Sad, Serbia

978-86-6253-197-1

Book of Abstracts of BioCompWaterClean Project Workshop “New Applications in Wastewater Treatment on the Way to Zero-Waste Technology”

38

1

https://biocompwaterclean.org/wp-content/uploads/2025/11/2025.11.04.-BoA-A4.pdf