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a b s t r a c tThe removal of trimethoprim (TMP) and sulfamethoxazole (SMX) by column experiments was systematically investigated, in which an artificial composite soil treatment system (ACST) simulating irrigation soils at high infiltration rates (>89.11 m d , and Zn 2+ during hydrogeochemical processes were focused in this study. The results demonstrate that ACST with high infiltration rates improved the removal of SMX and TMP, with removal rates about 20% higher than the removal rates of transitional sands. Moreover, under the condition of the same ACST infiltration rate, the removal rate of TMP was higher than that of SMX. This shows that influent high Na + concentrations might directly hinder the release of Ca , and Zn 2+ concentrations were on the µg L -1 level. In this study, the ACST is determined to be a suitable method for the treatment of water contaminated with SMX and TMP.

The high porosity of medium-coarse sand (MCS) layers in groundwater recharge areas presents a high environmental risk. Sulfamethoxazole (SMX) and trimethoprim (TMP) are two common sulfonamide antibiotics in surface water that have a high propensity to migrate into groundwater. In this study, four biochars were prepared and biochar-amended soil aquifer treatment (SAT) columns were constructed to remove SMX and TMP. Batch experiments demonstrated that the sorption isotherms conformed to the Freundlich model. The maximum adsorptions of biochars prepared at 700 °C were 54.73 and 67.62 mg/g for SMX and 59.3 and 73.38 mg/g for TMP. Electrostatic interaction may be one of the primary mechanisms of adsorption. The column experiments showed that the SMX and TMP removal rate of the biochar-amended SAT was as high as 96%, while that of the MCS SAT was less than 5%. The addition of biochar greatly improved the retention capacity of the pollutants in the MCS layer in the groundwater recharge area and effectively reduced environmental risk.