Background: Constructed wetlands are a promising, cheap and effective wastewater treatment in
small communities. The studies on these systems have been reported mainly from cold, tropical or
subtropical climate regions. In this work we constructed a pilot plant with six horizontal subsurface flow
constructed wetlands (HSSF CWs) with a surface area of 2 m
2 and a depth of 0.6 m each, planted with
Typha latifolia
or
Scirpus
sp., and filled with gravel (G) or fine gravel (FG) of 2.8 and 1.2 cm of diameter
respectively, continuously fed with raw domestic wastewater. This experimental setup was evaluated
over 280 days for the removal of organic matter and nutrients in a Mediterranean climate, near
Valparaíso, Chile. The removal of total COD, NH4
+-N and PO4
-3-P was calculated, in order to assess by
analysis of variance the effect of initial pollutants concentration, air temperature (season) and
plant/support combination on the wetlands performance.
Results: The
Scirpus/FG combination showed the highest average removal of total COD of about
59%, and
Typha/FG shows the highest removal of NH4
+-N and PO4
-3-P (49 and 32%, respectively).
Furthermore, the removal of organic matter was independent of influent concentration, while mildly
dependent of the season, unlike nutrients removal that was dependent on these two parameters.
Media, plant and the plant/media combination influenced positively organic matter, ammonia and
phosphorous removal, respectively.
Conclusions: Overall, the results demonstrate the potential of wetlands in treatment of wastewater in
Mediterranean regions and show how these can help to improve the quality of water in domestic zones
without high-throughput technologies.
