In addressing the challenges posed by conventional two-pass reverse osmosis (RO) plants, there has been a shift towards embracing cutting-edge technologies that cater to scenarios with consistently high Total Dissolved Solids (TDS) in feed water, requiring greater osmotic pressure for effective removal.
Traditionally, a two-pass RO plant involves feeding the second stage with permeate from the first, with the first stage achieve a recovery rate of no more than 40%. The second stage can attain recovery rates between 65% to 80%, depending on water quality. While this configuration enhances production and reduces reject water, some plants go a step further by implementing multiple passes to minimize rejected water. The final reject quantity is often subjected to heating and evaporation, allowing for the extraction of all water content, while the remaining salts are crystallized for alternative uses, mirroring the approach adopted by some companies such as SWCC_KSA . However, this configurations requires high capital and operational expenses in geneal, except if the existing plant has already some process to profit like power plants, petrochemical plants, etc. In Morroco there is an opportunity to evaluate for similar use in OCP Group complexes mainly Jorf, Safi and Laayoune..
Emerging technologies now offer innovative solutions for scenarios where continuously high TDS feed water demands increased osmotic pressure for effective treatment. Key components and considerations in this realm include membranes, pressure vessels, and power consumption.
- Membranes: Noteworthy advancements in RO membrane technology come from vendors like @saltwork and @hydranautics. They are pioneering ultra-high-pressure reverse osmosis (UHP RO) spiral-wound membranes capable of operating at pressures as high as 1,800 psi (124 bar). These membranes can achieve brine concentrations of up to 130,000 mg/L TDS, making them ideal for applications with elevated salt content. This innovation is especially relevant for Zero Liquid Discharge (ZLD) and Minimum Liquid Discharge (MLD) applications, enabling operation at exceptionally high pressures and salt concentrations.
- Power Consumption: The landscape of power consumption in desalination has been transformed by the introduction of @ERI’s new PX device, specifically the PX U40 and UHPRO models. These devices can operate at pressures up to 120 bar, a significant advancement from the current 83-bar limit. Accompanying this development is a specialized pump, the Ultra High-Pressure Exchanger device, enhancing the efficiency and capabilities of the desalination process.
- Pressure Vessels: Companies involved in the desalination process have proposed solutions to address the need for higher pressure vessels. Manufacturers such as Dax Industries and Pentair are now producing elements that can function at pressures of up to 103 bar, offering enhanced capabilities in handling high-pressure scenarios.
These technological advancements signify a paradigm shift in the desalination industry, providing more efficient and sustainable solutions for treating water with elevated TDS levels. As these innovations continue to mature, they hold the potential to revolutionize desalination practices and contribute to a more water-secure future.
