The effect of loading frequency and plants on the degradation of sulfamethoxazole and diclofenac in vertical-flow constructed wetlands

•Removal of DCF and SMX was higher at the lower loading frequency.•Reed canary grass reduced the removal of the pharmaceuticals.•The toxicity of the wastewater was reduced to the level of a negative control system.•Pharmaceuticals reduced bacterial diversity only in planted systems.•Nine SMX transformation products and one DCF transformation product were detected.