Published on IDRA Global Connections Fall 2021 Issue
By Dr. Ahmad Al Amoudi, Dr. Seungwon Ihm and Eng. Nikolay Voutchkov, Desalination Technology Research Institute (DTRI) of the Saline Water Conversion Corporation (SWCC), Saudi Arabia
The Desalination Technology Research Institute (DTRI) of Saline Water Conversion Corporation of Saudi Arabia (SWCC) has recently initiated a comprehensive program for the development of advanced technologies for mining of minerals and other substances from seawater desalination
brine. An addtional benefit from brine mining is the significant reduction of the volume of concentrate discharge to the sea and increase of the recovery of seawater desalination reverse osmosis (SWRO) process from 45% to 65% or more.
SWCC considers desalination plant brine to be a valuable resource rather than a waste. At present our focus is extracting sodium chloride and bromine, with plans in a later phase for production of of potassium chloride, magnesium salts, and rare metals such as rubidium, lithium and cesium. The revenue from selling these commodities can be used to subsidize the cost of water production, with the ultimate vision of ‘zero cost’ water.
Over the last two years DTRI has developed and patented an innovative system for concentration of brine from seawater desalination plants (Dual Brine Concentrator – DBC – see Figure 1) which is suitable to produce brine in liquid and crystal form as a source product for the chlor-alkali industry.
Figure 1. Schematic Diagram of Membrane Dual Brine Concentrator
The DBC consists of a nanofiltration (NF) system that removes a large portion of the calcium and magnesium contained in the source seawater, followed by a seawater reverse osmosis (SWRO) system that generates low salinity permeate suitable for drinking water after post-treatment, and concentrate (brine) with high content of sodium chloride.
The DBC is combined with subsequent membrane brine crystallization (BC) system; crystallizer and bromine production plant to generate high quality sodium chloride (NaCl) with purity of 99.6% and commercial grade bromine suitable for use in preparation of clear brine salts for oil well completion – see Figure 2.
Figure 2 – General Schematic of the Brine Mining Plant for NaCl and Br
In 2020, SWCC has signed memoranda of understanding (MOU) and entered negotiations of brine sales agreements with a number of chlor-alkali producing companies of Saudi Arabia to supply a total of 2 million dry tons/year (2 MM tpa) of high purity (99% or higher) sodium chloride as either liquid solution of 25% or as salt crystals. Based on these agreements SWCC intends to design, construct, and operate a 2 MM tpa brine concentration plant combined with a bromine production plant with installed capacity of 3,800 tons/year. The volume of brine needed for the JBCP to produce 2 MM tpa of sodium chloride (NaCl) crystal salt is 201,254 m3/day @ 75,000 mg/L of total dissolved solids (TDS) – which is approximately 16% of the volume of brine produced by the 1 MM m3/day Jubail 2 desalination plant.
The brine concentration plant will be located in the city of Jubail, Saudi Arabia and will receive SWRO brine from a greenfield 1 million m3/day SWRO desalination plant located in Jubail (Jubail 2 desalination plant) also known as the Jubail 2 desalination replacement project. A portion of the SWRO trains of this desalination plant will be equipped with a nanofiltration (NF) system with membranes capable of high rejection of calcium and magnesium from the source seawater. This NF system will operate at recovery of 75 to 85% and will produce permeate with low content of calcium and magnesium.
The brine generated from the NF system will be discharged through the outfall of the Jubail 2 SWRO desalination plant. A portion (10 to 18%) of the brine from the Jubail 2 SWRO desalination system will be directed to the Jubail Brine Concentration Plant (JBCP) and will be used as a source for production of high purity sodium chloride in crystal and liquid form suitable for use by the chlor-alkali industry. The site of the JBCP will be located adjacent to the site of the Jubail 2 desalination plant. Both plants will use the intake and outfall facilities of the Jubail 2 desalination plant.
Currently, the Jubail 2 desalination replacement project is at a stage of procurement of turnkey engineering, procurement, and construction (EPC) contractor. The EPC contractor for the JBCP will be retained under a separate procurement process which is targeted to begin in the late fall of 2021. The Jubail 2 SWRO desalination and the Jubail brine concentration plants will be operated by the SWCC.
