4. Conclusions
Ten pilot-scale, intermittently loaded vertical flow constructed
wetlands of different design and operation characteristics were
constructed and operated continuously for three years under
Mediterranean climatic conditions, simulating the first treatment
stage of real systems. The units proved to be quite efficient in
removal of the various pollutants (organic matter, nitrogen and
phosphorus), even though receiving high organic and hydraulic
loads. OM removal exceeded 78% or 105 g COD/m2 d as an average
of all units, for a mean influent COD of 510 mg/L (140 g COD/m2 d).
The mean nitrogen removal was 58% or 8.3 g N/m2 d (influent TKN
61 mg/L and 15.8 g/m2 d). Mean phosphorus removal for all units
reached 37% of the influent concentration (9.4 mg/L for TP), with
respective load removal at 0.93 g TP/m2 d (inflow 2.6 g TP/m2 d).
The continuous monitoring of the system performance revealed
useful suggestions for the optimum design of VFCWs: