*3.1. Reactor Configuration*

Four CWs were set up with 65 cm in height and 35 cm in diameter with the temperature maintained at 26 ± 3 ◦C and a relative humidity of 55–65%. The CWs were filled with siliceous gravel and sand (siliceous gravel: sand volume ratio = 1:1; siliceous gravel was 4–7 mm and sand was 5–8 mm in diameter). *Phragmites australis* were transplanted into the top layer. The synthetic wastewater was fed into four CWs from the bottom inlet by peristaltic pump with a hydraulic loading rate of 5 cm d−1. The synthetic wastewater was prepared with tap water containing chemical oxygen demand (500 mg <sup>L</sup>−1), ammonia nitrogen (40 mg <sup>L</sup>−1), total nitrogen (150 mg <sup>L</sup>−1), and total phosphorus (20 mg <sup>L</sup>−1). Then, 0, 20, 50, 100, and 200 μg L−<sup>1</sup> of SMX were spiked into synthetic wastewater for CW0, CW1, CW2, CW3, and CW4, respectively.
