Keywords: 2,4-D, wastewater, treatment, acidification, adsorption, reuse, pesticides, dichlorophenoxyacetic acids, dichlorophenols
Treatment and reuse of wastewater in pesticide 2,4-D production
Waste-water from the production of pesticide 2,4-D often contains high concentrations of 2,4-DCP and 2,6-D as the primary pollutants. Treatment of waste-water collected from a 2,4-D manufacturer was carried out using a technology combining acidification with hyper-crosslinked resin NDA-150 adsorption process. The overall process recovered 5.4 kg of 2,4-DCP and 0.6 kg of 2,6-D per cubic metre of the wastewater. The treatment reduced the concentration of 2,4-DCP in the wastewater from >6000 mg/L to <0.5 mg/L. The optimal operation parameters of adsorption and desorption were determined. The hyper-crosslinked resin adsorbent can be re-used after regeneration by NaOH aqueous solution. The recovered 2,4-DCP with a sufficiently high purity may be re-used in the production of 2,4-D. The technology may thus be applied to the treatment of waste-water for reclamation of chemicals for 2,4-D production while minimising the environmental nuisances and hazards that may be caused by these chemicals.