Removal of Herbicide Glyphosate in a Drinking Water Treatment System

Abstract

The removal efficiency of herbicide glyphosate in a drinking water treatment system was investigated. Four major processes of a drinking water treatment system were selected and experiments were performed separately including; treatments by sodium hypochlorite (NaOCl), a sedimentation process by PAC (polyaluminum chloride), ozonation and a GAC (granular activated carbon) treatment. In the sodium hypochlorite experiment, about 50% of the glyphosate was removed by 2 mg/L of hypochlorite and more than 90% was eliminated when 5 mg/L of NaOCl was applied. Also, AMPA, the main metabolite of glyphosate, was treated with hypochlorite. More than 30% of the AMPA was removed by 2 mg/L of hypochlorite and 50% by 5 mg/L. In the PAC experiment, it was determined that more than 60% could be removed. Further experiments were performed and the results indicated that the removed amount was dependent upon the amount of soil and upon the properties of the soil especially that of clay minerals. Ozonation could oxidize glyphosate to its byproducts at about a level of 50%. In contrast, when 1 mg/L of glyphosate was treated with GAC, the amount removed was negligible. The results of this experiment were conclusive. We confirmed that drinking water, which has been contaminated with water polluted with glyphosate can be effectively purified by the application of the drinking water treatment processes currently used

Glyphosate contamination in European rivers not from herbicide application?

“…We included disinfection processes commonly implemented in U.S. WWTPs because chlorination was shown to efficiently eliminate glyphosate (and partially AMPA). 29,30,31 Many WWTPs were equipped with this technique in the USA, but its use declined from 95% in 1997 to 75% of U.S. WWTPs in 2003. 32 The alternative UV disinfection (21% of U.S. plants in 2003 32 ) can be expected to be less efficient in glyphosate removal.…”