Treatability of s-triazine herbicide metabolites using powdered activated carbon

Widespread use of s-triazine herbicides such as atrazine, simazine, and cyanazine has led to the contamination of many ground-water and surface-water supplies with the parent compounds as well as by primary metabolites (e.g., deethylatrazine, deisopropylatrazine, and deethylcyanazine). Ozonation has been shown to produce many of the same byproducts. Activated carbon adsorption has been designated by the U.S. Environmental Protection Agency as the best available technology (BAT) for the treatment of herbicides in drinking water. Little data is available, however, on the applicability of activated carbon treatment for the control of the primary degradation products of herbicides. In this study, the adsorption of deethylatrazine, deisopropylatrazine (deethylsimazine), and deethylcyanazine on powdered activated carbon (PAC) was examined including development of Langmuir and Freundlich isotherm coefficients. It was found that deethylatrazine, deisopropylatrazine and deethylcyanazine were readily treatable using powdered activated carbon (PAC). However, the PAC's adsorptive capacity for deethylatrazine, deisopropylatrazine, and deethylcyanazine was generally less than for atrazine resulting in higher estimated carbon costs.