Constructed wetlands for domestic wastewater treatment in a Mediterranean climate region in Chile

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 m² 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.

Phytosociological and ecological structure of Mediterranean enclaves along the stream valleys in inner parts of black sea region.

In this study, phytosociological structure of Mediterranean enclaves which occured along the stream valleys in inner parts of Black sea region was investigated. Pinus brutia var. brutia and Quercus coccifera are the most widespread communities in the study area. Pinus pinea, Arbutus andrachne, Arbutus unedo, Fontanesia philliraeoides subsp. philliraeoides and Olea europaea L. var. sylvestris have a restricted distribution in inner parts of Black sea region as compared to P. brutia and Q. coccifera. The following associations were described in the study area. Siderito dichotomae -Quercetum cocciferae, Spiraeo crenatae-Oleetum sylvestris ass. nov., Cotino coggyreae- Arbutetum andrachnes, Buxo sempervirenti-Arbutetum unedonis ass. nov., Paliuro spinae-christi- Fontanesietum philliraeoidis, Querco infectoriae-Pinetum brutiae and Crucianello ponticae-Pinetum pinae. The highest species diversity was found in Crucienello ponticae- Pinetum pinae, while the lowest species diversity was found in Spiraeo crenatae-Oleetum sylvestris. Evenness values were much similar to each other among all of the associations. According to CA Paliurus spinae-christi-Fontanesietum philliraeoidis, Spiraeo crenatae- Oleetum sylvestris and Crucienello ponticae-Pinetum pinae occured in the negative zone. The other four associations occured in the positive zone.