industrial or specialized municipal use. To support this, Sulzer supplies dedicated second pass pumps, designed to maintain the necessary pressure and flow for this additional membrane filtration phase.
In addition, Sulzer can supply booster pumps to help integrate energy recovery devices( ERDs) into the RO process to significantly improve energy efficiency. ERDs capture the hydraulic energy from the high-pressure brine reject stream and transfer it back to the incoming seawater.
Nordic Water, a Sulzer brand, supplies advanced sand filters that efficiently remove particulates from the seawater, ensuring that only clean water reaches the membranes. To further enhance water quality, Sulzer’ s Chemtech division can supply static mixers where chemicals such as flocculants, coagulants, and biocides are evenly distributed throughout the water, optimizing the removal of contaminants. These mixers are able to deliver minimum pressure drop and effective mixing in a small footprint.
Throughout the pre-treatment process, the pumps maintain optimal flow rates at required pressure and efficiency, ensuring the continuous and stable operation of the plant. They will also provide the minimum required pressure towards high pressure pump and Energy Recovery Devices. By keeping the flow consistent, these pumps help minimize the risk of operational disruptions and maximize the efficiency of downstream processes.
Step 3: Reverse osmosis Once the seawater has been pretreated, it enters the actual RO stage— the heart of the desalination process. In this phase, seawater is pressurized and forced through
semi-permeable membranes that effectively separate salts from the water.
The membranes allow only water molecules to pass through, while the remaining concentrated brine— rich in removed salts— is discharged for safe disposal. This stage is highly energy-intensive, accounting for a significant portion of a desalination
plant’ s operational costs, making energy efficiency and precise pressure control critical to the process.
Sulzer plays a pivotal role in optimizing this phase by supplying high-pressure feed pumps. These are engineered to deliver the consistent, high-pressure flow required to push seawater through the RO membranes and typically account for more than half of a desalination plant’ s power consumption. This makes Suzer’ s ability to provide reliable, efficiency pumps a key element of running an effective operation.
In some desalination plants, a second pass of RO membranes is introduced to further refine the quality of the final product water. This additional stage ensures that the desalinated water meets even the most stringent purity standards, particularly for
Step 4: Post-treatment
After the RO membranes have filtered out the salts and impurities, the water is not quite ready to drink or use in industry just yet. Without essential minerals, it can taste flat or even slightly acidic, and over time, that acidity can cause corrosion in pipes and storage systems. That’ s why post-treatment is so important— it helps balance the water’ s composition, making it safer, more stable, and better-tasting.
In order to eliminate any acidity, carbon dioxide( CO 2) must be introduced following reverse osmosis and prior to remineralization. Sulzer’ s specialized static mixers play
a crucial role in this process by efficiently dissolving CO 2 gases directly into the water stream and ensuring thorough mixing within the main line. This innovative approach eliminates the need for dedicated CO 2 dosing or injection systems, simplifying the overall process and reducing the operational complexity.
At this stage, minerals like calcium and magnesium are added to improve the taste and ensure chemical stability. By fine-tuning the post-treatment process, Sulzer helps desalination plants deliver fresh, high-quality water that’ s ready for municipal, agricultural, or industrial use— while also protecting the systems that distribute it.
Issue 77 PECM 23