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Treatment of 2,4-D, mecoprop, and dicamba using membrane bioreactor technology.

Environmental science and pollution research international (2013-01-31)
Avik J Ghoshdastidar, Anthony Z Tong
ABSTRACT

Phenoxyacetic and benzoic acid herbicides are widely used agricultural, commercial, and domestic pesticides. As a result of high water solubility, mobility, and persistence, 2,4-dichlorophenoxyacetic acid (2,4-D), methylchlorophenoxypropionic acid (mecoprop), and 3,6-dichloro-2-methoxybenzoic acid (dicamba) have been detected in surface and waste waters across Canada. As current municipal wastewater treatment plants do not specifically address chronic, trace levels of contaminants like pesticides, an urgent need exists for an efficient, environmentally friendly means of breaking down these toxic herbicides. A commercially available herbicide mix, WeedEx, containing 2,4-D, mecoprop, and dicamba, was subjected to treatment using membrane bioreactor (MBR) technology. The three herbicides, in simulated wastewater with a chemical oxygen demand of 745 mg/L, were introduced to the MBR at concentrations ranging from 300 μg/L to 3.5 mg/L. Herbicides and biodegradation products were extracted from MBR effluent using solid-phase extraction followed by detection using high-performance liquid chromatography coupled with mass spectrometry. 2,4-D was reduced by more than 99.0 % within 12 days. Mecoprop and dicamba were more persistent and reduced by 69.0 and 75.4 %, respectively, after 112 days of treatment. Half-lives of 2,4-D, mecoprop and dicamba during the treatment were determined to be 1.9, 10.5, and 28.3 days, respectively. Important water quality parameters of the effluent such as dissolved oxygen, pH, ammonia, chemical oxygen demand, etc. were measured daily. MBR was demonstrated to be an environmentally friendly, compact, and efficient method for the treatment of toxic phenoxyacetic and benzoic acid herbicides.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2,4-Dichlorophenoxyacetic acid, ≥95%, crystalline
Sigma-Aldrich
Dicamba, suitable for plant cell culture, BioReagent
Supelco
Dicamba, PESTANAL®, analytical standard
Supelco
Mecoprop, PESTANAL®, analytical standard
Sigma-Aldrich
2,4-Dichlorophenoxyacetic acid, 97%
Supelco
2,4-D, certified reference material, TraceCERT®
Supelco
2,4-D, PESTANAL®, analytical standard
Supelco
2,4-D, PESTANAL®, analytical standard
Sigma-Aldrich
4-Chloro-2-methylphenoxyacetic acid, technical, ≥95.0% (T)
Supelco
Mecoprop-P, PESTANAL®, analytical standard
Supelco
2,4-D solution, certified reference material, 5000 μg/mL in acetonitrile
Supelco
MCPA, PESTANAL®, analytical standard