2.3. Remediation experiments
To investigate the efficiency of phosphate removal by plants, N. nucifera and C. alternifolius were used as the tested plants. The three month old plants, pre-cultured in plastic pots, were transferred to the pre-culture in 50 L pots containing 5000 g of soil and 40 L of tap water for a week. The total weight of plant for each pot was 4000 g. The constructed wetland system is shown in supplementary data ( Fig. S1). After 1 week, tap water was replaced by wastewater to start the experiment.