Effects of graywater on the growth and survival of ornamental plants in nature-based systems.

ABSTRACT

The current paper investigates the development of two ornamental plants, canna lily (Canna x generalis) and giant horsetail (Equisetum giganteum), at both bench and pilot scale. Combinations of gravel-filled mesocosm, planted and unplanted (control), irrigated with light greywater (GWL) or tap water (WT), were used. Both species were able to grow under the tested conditions with no indication of toxicity that could affect the development. Irrigation with GWL, resulted in higher evapotranspiration (2.2 mm-2.8 mm) in canna lily than giant horsetail (1.7 mm-2.3 mm) in mesocosm system. When the plants were mature and the season was more humid and warmer, canna lily and giant horsetail irrigated with GWL evapotranspirated 69.23% and 30.77%, respectively as compared to the unplanted GWL-irrigated-mesocosm. Principal components and cluster analysis identified similarity between evapotranspiration (ET) and the characteristics of the plants. Both species can thus be used in constructed wetlands taking into consideration elements such as the space available, level of water and solar incidence so as to allow the full development of the plants. The roots of giant horsetail require high water availability. Low solar incidence is indicated for giant horsetail, and the opposite for canna lily, if flowering is desired.