Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990, Israel.
French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, 84990, Israel.
Chemosphere. 2017 Oct;184:1012-1019. doi: 10.1016/j.chemosphere.2017.06.080. Epub 2017 Jun 19.
Greywater (GW) reuse for irrigation is a common method of reducing domestic consumption of fresh water. Most of the scientific research and legislation efforts have focused on GW's health risks, while less attention has been given to its environmental outcomes. One of the environmental risks of GW irrigation is its possible effect on soil hydraulic properties. This research examined the ability of GW to induce soil hydrophobicity, as well as its degree and persistence. Fresh water (control) and three model GW solutions representing raw, treated and highly treated GW were used to wet fine-grained sand. Every treatment was subjected to five cycles of wetting, incubation (at 5 °C or 30 °C) and drying (60 °C). After each cycle, capillary rise was measured and the contact angle (CA) was calculated. Samples were also tested by the Wilhelmy plate method to retrieve advancing and receding CA and reservoir surface tension. Water repellence of the sand, as implied from the CA, increased with increasing GW concentration and was highest in the sand coated with the model raw GW and incubated at 5 °C. However, none of the treatments resulted in what is considered to be "water-repellent soil". Furthermore, when raw GW-coated sand was immersed in water, its surface tension was significantly reduced relative to the other treatments, implying a release of surface-active compounds from the sand into the water. It was postulated that untreated GW may induce sub-critical water repellence in sand. However, this effect is sensitive to biodegradation and washing processes and is therefore temporary.
灰水 (GW) 再利用灌溉是减少家庭淡水消耗的常见方法。大多数科学研究和立法工作都集中在 GW 的健康风险上，而对其环境后果的关注较少。GW 灌溉的一个环境风险是其对土壤水力性质的可能影响。本研究考察了 GW 诱导土壤疏水性的能力，以及其程度和持久性。使用新鲜水（对照）和代表原水、处理水和高度处理水的三种模型 GW 溶液来润湿细砂。每个处理都经历了五次润湿、孵化（5°C 或 30°C）和干燥（60°C）循环。每次循环后，测量毛细上升并计算接触角（CA）。还通过威尔海米平板法对样品进行测试，以获取前进和后退 CA 和储层表面张力。从 CA 推断，砂的疏水性随 GW 浓度的增加而增加，在涂有模型原 GW 并在 5°C 下孵育的砂中最高。然而，没有一种处理导致被认为是“疏水土”。此外，当原 GW 涂覆的砂浸入水中时，其表面张力相对于其他处理显著降低，这意味着砂中的表面活性剂化合物被释放到水中。据推测，未经处理的 GW 可能会在砂中引起亚临界疏水性。然而，这种效果对生物降解和洗涤过程敏感，因此是暂时的。
