C. flabelliformis wetland had the highest annual average TN removal rate (52%), followed by A. calamus (47%), and V.
zizanioides showed the lowest value (35%). However, no significant differences were observed among the wetlands.
Average annual removal rates for SRP ranged from 30 to 70%. C. flabelliformis and A. calamus wetlands showed significantly
higher SRP removal rates than V. zizanioides wetland and P. australis wetland (P < 0.01 or P < 0.05).
All the wetlands showed high removal rates for COD and BOD5, with annual average removal rates 60–70% and 70–80%,
respectively. No significant differences for COD or BOD5 removal rates were observed among the wetlands (Fig. 4).