Articles
Residential graywater as an irrigation source for urban landscape plants
Article number
1409_25
Pages
183 – 190
Language
English
Abstract
Graywater is the untreated effluent that comes from laundry washing, showers and bathtubs, and might constitute 50% or more of the total wastewater produced in an average US household.
This graywater, if captured and reused, has the potential to meet a significant portion, or totality, of the supplemental irrigation needs of an average sized US residential landscape.
A greenhouse study evaluated the effects of irrigation with laundry graywater of varying composition for 18-weeks on the growth and quality of 12 landscape species: Agave angustifolia, Cuphea hyssopifolia, Dietes bicolor, Ilex vomitaria, Juniperus horizontalis, Lantana camara, Nerium oleander, Yucca filamentosa, Dianthus chinensis, Liriope muscari, Ophiogon japonicus and Trachelospermum asiaticum. The treatments were tap water (control), water with laundry detergent, water with detergent plus fabric softener, and water with detergent, softener and bleach (sodium hypochlorite). Results at the end of the irrigation period showed that with all these graywaters overall plant growth and aesthetic quality in Agave, Ilex, Juniperus, Liriope, Trachelospermum and Yucca was comparable to that of plants irrigated with just tap water.
For the rest of the species, growth and/or quality were negatively affected mostly or only when irrigated with graywater containing bleach. Cuphea, Lantana, Ophiogon and Dianthus had the worst effects with this graywater treatment, exhibiting significant browning and necrotic leaf tissues (Dianthus, Ophiogon) and chlorosis (Lantana, Cuphea). These responses and symptoms were mostly attributed to specific ion (toxicity) effects, namely higher free chlorine, sodium, chloride and boron concentrations in the applied solution, drainage effluents and/or plant tissues in the graywater with bleach, compared to the other graywaters and the tap water control.
This graywater, if captured and reused, has the potential to meet a significant portion, or totality, of the supplemental irrigation needs of an average sized US residential landscape.
A greenhouse study evaluated the effects of irrigation with laundry graywater of varying composition for 18-weeks on the growth and quality of 12 landscape species: Agave angustifolia, Cuphea hyssopifolia, Dietes bicolor, Ilex vomitaria, Juniperus horizontalis, Lantana camara, Nerium oleander, Yucca filamentosa, Dianthus chinensis, Liriope muscari, Ophiogon japonicus and Trachelospermum asiaticum. The treatments were tap water (control), water with laundry detergent, water with detergent plus fabric softener, and water with detergent, softener and bleach (sodium hypochlorite). Results at the end of the irrigation period showed that with all these graywaters overall plant growth and aesthetic quality in Agave, Ilex, Juniperus, Liriope, Trachelospermum and Yucca was comparable to that of plants irrigated with just tap water.
For the rest of the species, growth and/or quality were negatively affected mostly or only when irrigated with graywater containing bleach. Cuphea, Lantana, Ophiogon and Dianthus had the worst effects with this graywater treatment, exhibiting significant browning and necrotic leaf tissues (Dianthus, Ophiogon) and chlorosis (Lantana, Cuphea). These responses and symptoms were mostly attributed to specific ion (toxicity) effects, namely higher free chlorine, sodium, chloride and boron concentrations in the applied solution, drainage effluents and/or plant tissues in the graywater with bleach, compared to the other graywaters and the tap water control.
Authors
R.I. Cabrera, J.E. Altland
Keywords
alternative sources, laundry effluents, water quality
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