Enhancement of Physicochemical Properties of Dubai’s Sand to Conserve Irrigation Water

Abstract

Freshwater scarcity has been a considerable issue in the Gulf Region. The cities in the region including in the UAE depend mainly on seawater desalination. Their demand escalated about 15% annually regardless of seawater desalination direct cost of 1 US$/M³. Thus, calling all water conservation techniques to reducing indoor and outdoor water demands is inevitable. Using Hydrophobic Sand (HS) to reduce water seepage and increase the contact time between irrigation water and plants’ roots was seen as potential conservation technique. The HS is Normal Sand (NS) coated by a thin layer of hydrophobic organic silica compound called trimethylsilanol. However, concerns were raised about the leaching of harmful organic coating chemicals into the soil and groundwater. Assessing the potential risks of leaching additives is one of the objectives of this research. For some plants, requiring a certain range of soil permeability suggests a mixture of NS and HS. The permeability of mixtures of HS with abundant NS was examined to assess its validity and cost effectiveness when a certain permeability is required. Several elements leaching tests were conducted. The soil was classified and constant head permeability test was conducted for different configurations and mixtures of NS and HS. The leached elements, nutrients and organic silica were within the allowable limits set by the typical standards. Further experiments indicates that HS does not constitute an environmental hazard. Mixing different portions of NS and HS revealed unforeseen increase in the permeability. Instead, some layer configurations could reduce soil permeability.