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The availability of freshwater on earth is very less and a noticeable worry about the shortage of freshwater has emerged during the last decade especially in the Middle East and North Africa (MENA) countries. Most of the freshwater demands are provided by the desalination of seawater both thermal or membrane desalination technologies and desalination plants produce huge volumes of concentrated brine which are discharged back to the sea. This brine contains greater concentration of commercially valuable minerals than that in seawater. The literatures reported that the current disposal options have a number of severe limitations that are associated with technical challenges and environmental issues. As such, research studies have remarkably carried out into the development of mineral extraction processes with aim of producing valuable minerals from desalination brine. Therefore, this paper will review the appraisal of extraction of valuable minerals from Kuwait seawater desalination brine. To achieve this goal, bench-scale experiments were conducted by adopting suitable technologies present in the recent literature. Chemical precipitation method was experimentally implemented at Water Research Center (WRC) of Kuwait Institute for Scientific Research (KISR) with aim of extracting valuable minerals, including magnesium, calcium, boron, sulfate, and strontium, from the rejected brine of the main seawater reverse osmosis desalination units of Desalination Research Plant (DRP) and Shuwaikh Water Distillation Plant (SWDP). The mineral extraction experiments were performed by using sodium hydroxide as base at different processing temperature and pH. The results showed that the amount of extraction of minerals from Doha RO brine was 7.280 g/L. The major extracted mineral magnesium is about 98% and other minerals are lithium 78%, boron 51%, sulfate 18%, calcium 15%, and strontium 14%. For Shuwaikh brine, percentage of extracted minerals are boron 83%, magnesium 78%, lithium 34%, strontium 21%, calcium 18%, and sulfate 11% at 90°C at 10.0 pH. Based on the experimental data and mathematical calculations, the production of magnesium oxide from DRP and Shuwaikh RO plants is around 231 and 97,910 ton per year. The annual benefit from magnesium oxide production using Doha and Shuwaikh brine are 577,500 US$/Y and 244,775,000 US$/Y, respectively. [ABSTRACT FROM AUTHOR]

The brine disposal from desalination plants and its environmental impact are the major challenges faced by the desalination industry all over the world. The desalination brine contains higher concentration of inorganic compounds than that in seawater in addition to the chemical additives used by the pre-treatment units. The precipitation of minerals from brine reduces the fresh water production cost as well as minimizes the brine disposal problem. This article explores a systematic approach for the brine treatment problem by assessing the performance of mineral precipitation using chemical precipitation technique for precipitating valuable minerals, including magnesium, calcium, boron, sulfate, and strontium, from the rejected brine of two seawater reverse osmosis (SWRO) desalination plants in Kuwait. The preliminary mineral precipitation results showed that sodium hydroxide is the best suitable base for precipitation of all minerals compared with calcium hydroxide and ammonium hydroxide. Further, the mineral precipitation experiments were performed by using sodium hydroxide as base at different processing temperature and pH. The results showed that more than 78% of magnesium (Mg) was precipitated from RO brine at pH 10 and temperature of 90°C. The preliminary economic evaluation of magnesium oxide production using RO brine of desalination plants at Doha Desalination Research Plant and Shuwaikh sites of Kuwait are 228 and 97,909 tons per year, respectively. Overall, this study established optimum operating condition for effective precipitation of minerals from high saline Arabian Gulf SWRO brine with high efficiency and showed promising results for large-scale mining. [ABSTRACT FROM AUTHOR]

The separation performance of solid layer freeze crystallization (SLFC) processes for desalting saline waters under the influences of end-point temperature, cooling rate, feed concentration, and agitation rate was investigated. The investigated SLFC processes are static freeze crystallization (SFC) and three different types of dynamic freeze crystallization (DFC) systems agitated by bubbling process (BP), a mechanically stirred system (MSS), and an ultrasonic process (UP). The NaCl feed solution concentrations used were 0.5, 3.5 and 7 wt%. The SFC system was able to achieve the maximum salt rejection of 3.12%, 14.10%, and 14.26% for feed salinities of 0.5, 3.5, and 7 wt%, respectively. The DFC system agitated by BP achieved 50.34%, 30.70%, and 19.90% maximum salt rejection for feed salinities of 0.5, 3.5, and 7 wt%, respectively. The DFC system agitated by MSS achieved 70.20%, 37.30%, and 14% maximum salt rejection for feed salinities of 0.5, 3.5, and 7 wt%, respectively. The DFC system agitated by UP was able to achieve the maximum salt rejection of 84%, 34%, and 28% for feed salinities of 0.5, 3.5, and 7 wt%, respectively. The experimental results were encouraging and may be used to develop a hybrid system combining the membrane based process (such as reverse osmosis or forward osmosis technology) with the most suitable SLFC system, on a pilot scale, for further research and development. [ABSTRACT FROM AUTHOR]

This paper aimed at assessing the feasibility of the forward osmosis (FO) membrane process step of the FO desalination process, on a laboratory bench-scale test unit using batch mode, for extracting freshwater from feed and simultaneously diluting draw solution (DS). A commercially available spiral wound FO membrane made of cellulose triacetate (CTA) was experimentally tested at different operating conditions. Several affecting parameters, namely, feed concentration, draw solute concentrations, flow rate, and temperature, on water flux and permeate water recovery ratio were investigated. Deionized (DI) water, sodium chloride (NaCl) solutions, Gulf seawater and reverse osmosis (RO) brine were used as feed solutions (FS). Different concentrations of NaCl solutions ranging from 3.5 to 26 wt% were used and tested as DS. The results showed that the water flux increased with increasing DS osmotic pressure. The experimental results indicated that the water flux is dependent on the temperatures of FS and DS. It was observed that the water flux is directly proportional to the temperature of the FS and DS. The experimental results were highly encouraging, and proved that the FO membrane stage could be an efficient desalination system component for either desalting seawater or concentrating highly saline waters including RO brine. [ABSTRACT FROM AUTHOR]