Abstract

This study provides the basis for implementing a novel continuous treatment system for wastewater containing the pesticide atrazine (ATZ). Adsorption isotherms of ATZ from aqueous solution onto four biomixtures were determined. Based on the adsorption results, biomixture "B" (wheat straw, soil, and peat) was selected as the packing material for the fixed-bed column (FBC). The Response Surface Methodology (RSM) was used to optimize the combined effect of the inlet ATZ concentration (5-15 mg L-1), flow rate (10-50 mL h(-1)), and pH (4-8) of the FBC packed with biomixture "B" on ATZ removal. The dynamic behaviour of the FBC was investigated using the Thomas model under the optimal conditions obtained from the RSM. The results showed that pH was the determining factor in the adsorption process. Moreover, adsorption of ATZ decreased when the ATZ concentration and flow rate increased, especially at a basic pH. The optimum conditions for the adsorption of ATZ were a pH of 4.07, an influent ATZ concentration of 7.18 mg L-1, and a flow rate of 34.24 mL h(-1) that resulted in the removal of 98.6% of the ATZ (corresponding to an adsorption capacity of 95.32 mg g(-1)). The Thomas model described the adsorption process to be well under optimal conditions (R-2 = 0.9829). The findings of this study demonstrate that biomixture "B" could be successfully used as a low-cost adsorbent to remove ATZ from aqueous solution under continuous conditions. (C) 2020 Elsevier B.V. All rights reserved.