Reclaimed water use optimization in the Middle East

Groundwater resources in the Middle East are being used at unsustainable rates as populations grow and water demands increase. Desalination is a critical source of potable water, especially in the GCC nations. However, desalination is very energy intensive and costly and is mainly suitable for high-value uses such as potable supply. Surface water in the Middle East is rare; the only other water supply source of significance in the region is reclaimed water. Reclaimed water use is increasing throughout the region. Uses of reclaimed water include irrigation and industrial use, saline intrusion barriers, and indirect potable reuse, generally in an unplanned manner. Implementation of reclaimed water use involves four main stages, from immature to mature, though optimization. During the optimization stage, the best uses for reclaimed water are given priority as well as increased cost recovery applied through tariffs. As reclaimed water use nears 100%, Aquifer Storage and Recovery (ASR) can become an important element of reclaimed water use optimization, thereby allowing supply to keep up with varying demand and ensuring consistent supply to paying customers. ASR does not work in all hydrogeological or hydrochemical settings. Factors determining success or failure of below ground water storage of reclaimed water are explored as well as water quality considerations. Water quality concerns for reclaimed water include potential acute concerns (e. g. bacteriological exposure) and potential chronic concerns such as heavy metals and Contaminants of Emerging Concern (CECs). Potential contaminant migration and attenuation mechanisms associated with reclaimed water in the subsurface are discussed. Proper use of reclaimed water includes application of the multiple barriers principle to ensure protection of public health and the environment. Multiple barriers can come in the form of various treatment trains and separation of reclaimed water application from potential receptors (e. g. potable water supplies). Different levels of treatment can be used, depending on the eventual use of the water, as water quality should only be sufficiently high to meet needs. An example of this would be that removal of nitrates to meet drinking water standards is undesirable for water which is used for irrigation purposes. Optimization of the use of reclaimed water using managed aquifer recharge in the Middle East, particularly in the GCC nations, is explored.