Figure 4: A smaller constructed subirrigated wetland system showing the gravel filter
and growing bed.
of micro-organisms in the system.
Both nitrogen and phosphorus are used and transformed within a wetland system. The nitrogen removal
efficiency of a wetland system is extremely high and is
highest when water temperatures are higher. The rate
of phosphorus removal can be quite variable and is
mainly the result of binding to sediment particles rather than through uptake by the plants. When the sediment nears a saturation point for the binding of phos-
Figure 5: A series of smaller constructed wetland
systems containing different plant species.
phorus, release of phosphorus can occur resulting in a
negative removal percentage. The use of clay-based
substrates can however increase the removal efficiency
of phosphorus in constructed wetland systems.
In our pursuit to find integrated methods to increase
the sustainability of agricultural production, constructed wetlands is a low cost and low maintenance method
that can help manage wastewater from greenhouses.