Impact of electrochemically treated greywater on green wall and roof irrigation: Effects on soils and plants

Abstract

Indexación: ScopusAs part of a study on the treatment and reuse of greywater, the potential use of greywater for irrigating green walls and roofs was assessed, with the focus on its effects on the substrate and vegetation. The response of three ornamental species common in central Chile, Chlorophytum comosum (loose spider plant), Dymondia margaretae (silver carpet) and Hedera helix (common ivy), was evaluated under irrigation with untreated washing machine greywater, greywater treated by electrochemical processes and potable water (used as a control). The experimental work was conducted over 12 months using 60 pots installed on a green wall (20 per irrigation type), exposed to the climate conditions of Santiago de Chile. Periodic measurements were taken of the substrate (pH, electrical conductivity, organic matter and phosphorus) and of the plants (leaf count and size, presence of foliar spots and pigment analysis) to evaluate growth, health and signs of biological stress in response to the different irrigation waters. Irrigation with electrochemically treated greywater maintained soil pH within neutral ranges and limited salinity to levels suitable for moderately tolerant plants. In contrast, untreated greywater led to higher electrical conductivity values. No significant differences were detected in soil organic matter or phosphorus content among the different types of water. After an initial adaptation, plant growth with treated greywater matched or exceeded growth with potable water. There were no major alterations in pigment composition or visible stress symptoms. These results suggest that electrochemically treated greywater is a viable sustainable option for irrigating green walls and roofs. © 2026 Elsevier Ltd.Acknowledgements The authors acknowledge the funding provided by the Chilean National Agency for Research and Development (ANID) under the Project ANID ANILLO ATE 220024 and Millenium Institute on Green Ammonia as Energy Vector MIGA, ANID/Millennium Science Initiative Program/ ICN2021_023.S