2.2.Reed bed based on type of Construction
2.2.1. Surface Horizontal Flow (SHF)
This design allows water to flow over the surface of
the bed between the stems of the reed plants which
are planted in earth. The water is visible, usually to
a depth of around 150mm. The design is effective
for settling out solids prior to further treatment, or to
balance flows into further reed bed stages.
Figure 4: Types of reed beds based on its
construction
2.2.2. Subsurface Horizontal Flow (SSHF)
This design allows water to flow below the surface
of the reed bed through gravel media. The reed
plants are planted in the gravel. There is no visible
water in the bed and as such presents no public
safety of odour problems. The reed plants are
allowed to dieback in winter and form a warm
composted layer which protects the biofilm below.
This design if effective in reducing SS, BOD, COD
and partial ammonia removal. It is also effective in