single-stage CWs cannot achieve high
removal of TN (Vymazal, 2005, 2007). In this regard, various types
of CWs may be combined to leverage the advantages of individual
systems. As many wastewaters may be difficult to treat in a singlestage
system, hybrid systems which consist of various types of
constructed wetlands staged in series have been introduced. Most
hybrid systems are comprised of VSSF and HSSF systems arranged
in a staged manner (Vymazal, 2011, 2007). The VSSF CW is intended
to remove organics and suspended solids and to provide nitrification,
while denitrification and further removal of organics and
suspend solids occur in HSSF CW.