Constructed wetlands can improve wastewater purification in the Mediterranean
Lay summary by Alexandros Stefanakis
A new study from Italy reports that pilot-scale Constructed Wetlands planted with common reeds can be effectively used as the final treatment stage in conventional wastewater treatment plants.
Climatic conditions in the Mediterranean basin are ideal for the implementation of the green treatment technology of Constructed Wetlands. The basic element of these systems is the use of plants which enhance the wastewater treatment processes. It is generally believed that the presence of plants promotes the treatment efficiency, in order to provide a treated effluent appropriate for varying reuse options.
In this study, four different plant species are tested in pilot-scale horizontal subsurface Constructed Wetland units and compared with a similar unplanted unit. The goal is to identify whether the presence of plants improves the overall treatment efficiency or not and which plant species gives the best treatment results.
The researchers run and monitored the experimental units for a nine months period, during which influent and effluent samples were regularly taken and analysed for the determination of the various chemical, physical and microbiological wastewater pollutants. They found that all planted units showed a better performance than the unplanted one, which implies the significant contribution of plants to the treatment. Moreover, the Constructed Wetland unit with the common reed species (or P. australis) showed the highest pollutant concentration decrease and the highest evapotranspiration rates.
This study represents a clear indication that Constructed Wetlands can be used as tertiary stage to upgrade existing conventional wastewater treatment plants. Especially if planted with common reeds, these systems could provide an effluent of high quality which could be potentially recycled for agricultural purposes.
For further information
Read the Ecological Engineering original research article which this summary is based on ‘Comparison of removal efficiencies in Mediterranean pilot constructed wetlands vegetated with different plant species’ (February 2015).
Visit the profile of the research ambassador, Alexandros Stefanakis, who wrote this summary.
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