4. Discussion
In the original concept Primary SSVFW, SMOPs and SSVFW were
designed to play different roles. Firstly, Primary SSVFW was to promote sedimentation of TSS in raw water, thus increasing the water
transparency to the benefit of the submerged macrophytes growing in the SMOPs. Additionally, Primary SSVFW was to promote
the microbial ammonification of ORG-N. Secondly, oxygen generated by SAV photosynthesis in SMOP sections provided an aerobic
environment for nitrification and at the same time stimulated the
release of organic matters as a carbon source for denitrification in
the last SSVFW. Finally, denitrification in SSVFW was thought to
completely remove nitrogen