Impact of chemical composition of reject brine from inland desalination plants on soil and groundwater, UAE

Abstract

Water is an essential component for the survival of mankind on earth and has been generally considered as an abundantly available resource. However, many countries in the world, particularly of the Gulf Region are suffering water scarcity. Also, countries with abundant water resources are facing problems due to deteriorating quality of the available water resources and their uneven geographic distribution. Water shortages in UAE are aggravating by rapidly growing population, and expansion of industrial, and agricultural activities. This situation necessitated the finding of alternative water resources to augment existing supplies. This has resulted in the development of different desalination technologies for production of potable water using sea and brackish water as feed. Between 1999 and 2001, the desalination water production in the UAE has increased by 30% of the existing production capacity, due to the remarkable economic and demographic development. The recovery rate is generally around 50% in seawater desalination and around 60–80% in desalination of brackish water. The reject brine from the seawater desalination is generally discharged to sea. But in some special cases, particularly small capacity plants, it is discharged to wadies. In the inland desalination plants brackish water is the feed source and rejects brine is disposed using evaporation ponds, deep well injection, discharge to the surface, etc. Therefore, there is a possibility for soil and groundwater contaminations with chemical constituents from various sources (i.e. reject brine, pretreatment waste and cleaning waste of desalination plants). The major constituents of reject brine are inorganic salts. The brine also contains small quantities of antiscale additives, corrosion products, and other reaction products. The aim of the present study is to determine the composition of discharge brine from various inland desalination plants and investigate the effect of these brines on the soil and underground aquifers. Water and soil samples from these sites were collected and analyzed for physical, chemical and mineralogical. Water quality data for previous years has been collected from several sites of inland desalination plants in UAE and analyzed. Also, Water Quality Data Management Software has been utilized to simulate the mobility and the generated plume of major constituents of the reject brine in the disposal surroundings.