AWWA MTC69792

Recently commissioned Vitens nanofiltration (NF) and reverse osmosis (RO) treatment plants were provided with the Optiflux® stack configuration. Optiflux® is the optimization of the permeate productivity of spiral-wound NF and RO membrane filtration plants, in relation to the permeate quality and the occurring concentration polarization. This design shows that optimization of permeate productivity has to be done by minimizing hydraulic losses and the osmotic pressure difference across membrane surface. An increase in permeate productivity of 20% can be achieved, for both NF and RO membrane filtration systems, by lowering the number of membrane modules per pressure vessel to three, which leads to lower hydraulic pressure losses. In Dinxperlo, the difference in feed pressure between the traditional design (800 kPa) and the Optiflux® design (720 kPa) is calculated, in spite of the equal flux of 25.6 l/m²/h in both designs. If the traditional feed pressure of 800 kPa is applied to the Optiflux® stack design, the flux increases to 28.8 l/m²/h. This results in a permeate production of 90 m³/h instead of 80 m³/h in the traditional design. This is a significant increase in permeate flow of 12.5 %, with a corresponding installed membrane surface and energy consumption. The study concludes that an Optiflux® design with 3 elements per stage in center port pressure vessels is an interesting economical alternative for the traditional NF and RO designs. The yield will gain if we take into account the expected future increase in energy costs and reduction in pressure vessel costs. Includes 5 references, tables, figures.