Ultra-filtration and Partial Softening in Water Treatment
20 Oct 2022
Valve solutions for drinking water treatment: In a successful municipal water treatment application that treats 300m³ of water per minute, GEMÜ provides reliable valve solutions for ultra-filtration and partial softening processes.
Process Description Ultra-filtration UF
After coarse filtration, the water is fed to the Ultra-filtration passing through porous membranes with a pressure drop of 0,1-0,8 bar. This retains the finest solids, turbidity and pollens, as well as bacteria from passing through the membrane. However, the water containing dissolved ingredients such as hardness components or minerals, and small molecules can still pass through.
Partial softening and regeneration
Ion exchange reduces the concentrations of hardness components (calcium and magnesium), and undesirable substances such as nitrates, sulphates and chlorides, by half from the sanitised water. Carbonic acid is generated as a by-product and dissolves into water and carbon dioxide (CO2). The pure-water degasifier then removes the excess CO2 before transferring the treated water to a pure-water container and feeding it into the municipal water supply following UV sterilisation. This reduces the water hardness from a hard Ultra-filtration and Partial Softening in Water Treatment level (480 ppm CaCO3) to a medium level of 240 ppm CaCO3.
Raw water enriched with CO2 is used as a regenerating agent for the mixed- bed filter, reversing the direction of the exchange process where high pressure dissolves CO2 to create carbonic acid. The carbonic acid is then fed in the counter current over the mixed-bed, regenerating the ion exchanger resin. About 95% of the CO2 required for regeneration can be recovered and fed back into the process.
GEMÜ products in use
All treatment processes for both raw and treated water distributions use GEMÜ 480 Victoria series butterfly valves (up to DN 400), GEMÜ D450 plastic butterfly valves range, GEMÜ 717 manual plastic ball valves and GEMÜ LSC limit switch box for quarter turn actuators.
GEMÜ offers the next generation of rubber lined butterfly valves, the R480 Victoria series, as a direct replacement for the GEMÜ 480, offering multiple enhanced product features.
Thanks to its flow-optimised and sleek disc design, the R480 series achieves higher flow rate factors. This reduces the pressure loss, giving the butterfly valves greater energy efficiency. The PTFE-coated bushes reduce torques, not only allowing further savings through lower actuator costs, but also making the valves significantly more durable and therefore increasing longevity. Furthermore, the technical optimisation of the liner improves tightness, which guarantees bubble- tight sealing and resistance to slipping.
With its wide range of valves and accessories, as well as measurement and control instrumentation, GEMÜ provides an optimal solution from a single source, saving the customers time, effort and cost, not only in logistics and installation but also in documentation.
In addition, plastic butterfly valves and ball valves used in this application are available in various actuator and material versions.