Greywater for Desert

With over one billion people across a hundred countries thirsting for a solution to desertification, the Ben-Gurion University of the Negev (BGU) Zuckerberg Institute for Water Research set out to find a solution for optimal living conditions in arid environments.

Research into greywater reuse for agricultural irrigation to date was primarily focused on health risks of using greywater for human consumption. These concerns were put to rest by Zuckerberg Institute researchers in 2015. Their finding enabled scientists to delve into the next stage of greywater research: how it affects environmental outcomes, particularly on soil properties in different ecosystems.

A new study conducted by Prof. Amit Gross of the Ben-Gurion University of the Negev Zuckerberg Institute for Water Research has revealed that biofiltration treatment of greywater is more efficient for irrigation in arid, sandy soils.

Prof. Gross and his research team found that greywater does not infiltrate through the soil as easily as freshwater and is slower to reach plant roots, causing a condition known as greywater-induced hydrophobicity. Instead of infiltrating into the ground as freshwater does, the water collects on the surface of the soil, leading to possible erosion.

Greywater-induced hydrophobicity disappears quickly following rainwater or freshwater irrigation events, but it is a more significant concern in arid lands with negligible rainfall.

In the study, the researchers examined how greywater induces soil hydrophobicity, as well as its degree and persistence. They created three greywater models using raw (untreated), treated, and highly treated greywater to irrigate fine-grained sand compared to a freshwater control. The result was that only the raw greywater irrigated soil showed hydrophobicity, which could be mitigated with both moderately and highly treated solutions. Biofiltration treatment was demonstrated to degrade the hydrophobic organic compounds thus eliminating the hydrophobicity problem.

Onsite reuse of greywater 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. As many government authorities are establishing new guidelines, the results of this study reinforce the recommendations to treat greywater before reusing for irrigation, particularly in arid regions.

Source: JerusalemOnline.com