News | July 12, 2017

Using Treated Graywater For Irrigation Is Better For Arid Environments Than Non-Treated Graywater According To Ben-Gurion University Research

Reusing graywater in dry areas may require treatment for more efficient irrigation in arid, sandy soils, according to a new study published in Chemosphere by researchers at the Ben-Gurion University of the Negev (BGU) Zuckerberg Institute for Water Research.

Graywater includes any wastewater generated in households or office buildings except from the toilet.

Graywater use has been proven safe for agriculture irrigation. "Most of the scientific research and legislation efforts have focused on graywater's health risks, while less attention has been given to its environmental outcomes, including its effect on soil properties," says Prof. Amit Gross, head of the Department of Environmental Hydrology and Microbiology in the Zuckerberg Institute.

Prof. Gross and his team found that graywater does not infiltrate through the soil as easily as fresh water and is slower to reach plant roots. It can also cause water runoff leading to erosion.

"This condition, called ‘graywater-induced hydrophobicity,’ is likely temporary and disappears quickly following rainwater or freshwater irrigation events,” says Prof. Gross. “However, it is a more significant concern in arid lands with negligible rainfall as compared with wetter regions.”

According to the researchers, treating the graywater using biofiltration to degrade the hydrophobic organic compounds will eliminate the problem.

In the study, the researchers examined how graywater induces soil hydrophobicity, as well as its degree and persistence. They created three graywater models using raw, treated and highly treated graywater to irrigate fine-grained sand compared to a freshwater control. The result was that only the raw graywater irrigated soil showed hydrophobicity, which could be mitigated with both moderately and highly treated solutions.

“Onsite reuse of graywater for irrigation is perceived as a low risk and economical way of reducing freshwater use and, as such, it is gaining in popularity in both developing and developed countries," says Prof. Gross. “As many government authorities are establishing new guidelines, the results of this study reinforce the recommendations to treat graywater before reusing for irrigation, particularly in arid regions.”

Other researchers who collaborated on the study were Ph.D. candidate Adi Maimon of the Department of Environmental Hydrology and Microbiology and Dr. Arye Gilboa of the French Associates Institute for Agriculture and Biotechnology of Drylands.

Together with the Swiss Institute for Dryland Environmental and Energy Research, the institutes comprise BGU’s Jacob Blaustein Institutes for Desert Research on its Sede Boqer Campus.

About American Associates, Ben-Gurion University of the Negev
American Associates, Ben-Gurion University of the Negev (AABGU) plays a vital role in sustaining David Ben-Gurion's vision: creating a world-class institution of education and research in the Israeli desert, nurturing the Negev community and sharing the University's expertise locally and around the globe. As Ben-Gurion University of the Negev (BGU) looks ahead to turning 50 in 2020, AABGU imagines a future that goes beyond the walls of academia. It is a future where BGU invents a new world and inspires a vision for a stronger Israel and its next generation of leaders. Together with supporters, AABGU will help the University foster excellence in teaching, research and outreach to the communities of the Negev for the next 50 years and beyond. For more information, visit vision.aabgu.org.

SOURCE: American Associates, Ben-Gurion University Of The Negev