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harvesting. For the chlorinated phenolic compounds, most of the pollutants were absorbed
by the roots of the plants and a low amount was translocated to the shoots for both the
pilot-scale CW and the pot experiment. Based on the results,
P. australis americanus
appears to be the best plant species for the biosorption of chlorophenols. High amount of
dioxins and furans were also detected in the aerial parts of P.
australis americanus,
but the
origins of those pollutants have not been determined yet.
The pilot-scale CWs were able to achieve a high removal of pollutant from the water during
the 2013 summer. Compared to the mean inlet of pollutants, the metals concentration of the
outlet of each wetland was about 3 fold lower for the arsenic, 20 fold lower for the
chromium and 15 fold lower for the copper. For metal removal, all CW pilots exhibit
removal higher than 60 %. For dioxins and furans, the removal rates were nearly 100 %
with a mean affluent of 165 ng/L TEQ and an effluent varying from 3.53 to 7.72 ng/L TEQ
(TEQ = toxicity equivalence). For the chlorophenols, the concentration of the inlet and
outlet varies too much to calculate adequately the removal rate.
Conclusions
The three indigenous plants species tested in this study are able to tolerate high level of
pollutants (about 100 fold higher than the average concentration of the leachate). Moreover
they exhibit treatment efficiency comparable to the invasive
P. australis australis
.
According to these two observations they appear as good candidates to be used in full-scale
constructed wetlands system to treat water contaminated with wood preservatives. To go
further and to see the long-term effect on the pilot’s CW treatment efficiencies, these
preliminary results will be complemented with further data collected during summer 2014.
Further research will be conducted to relate the treatment capacity of the CW to the plants
roots and the microorganism associated with the rhizosphere of each macrophytes species.
References
Brisson. J. and Chazarenc. F. (2009). Maximizing Pollutant Removal in Constructed
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Chang. F.-C.. Wang. Y.-N.. Chen. P.-J. and Ko. C.-H. (2013).
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Crosby. D. G. B.. K. I.; Greve. P. A.; Korte. F.; Still. G. G.; Vonk. J. W. (1981).
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