McCauley, Margaret. 1999. What are those plants doing? A comparison of the water quality treatment effectiveness of three plant species in a constructed wetland for municipal wastewater treatment. M.S.
The effect of plant species on water quality was examined. Nine plots were planted--three plots each of Schoenoplectus acutus, Typha latifolia, and Phalaris arundinacea--and one plot was left unvegetated as a control. Water quality was tested approximately every three weeks. The experimental plots did not bring the inflow down to secondary treatment standards, which is not surprising given their small size and approximately 2.5 day retention time. There were no strong overall treatment differences found among the species, but there were a number of minor, biologically relevant treatment effects including:
1. Schoenoplectus acutus appears to have a treatment effect for total phosphorus.
2. The presence of macrophytes does improve water treatment effectiveness, particularly removal of biological oxygen demand.
3. Differences in treatment effectiveness among emergent species are more pronounced in warmer months.
4. Continuous standing water will kill Phalaris arundinacea.
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