Limewater production in waterworks by a closed-loop membrane process

Abstract

To produce lime water for drinking water treatment, a method based on membrane technology and circulation has been designed and tested in pilot scale with direct interfaces to the waterworks Ebnet of bnNETZE GmbH company. The solvent water is produced from raw water by reverse osmosis and mechanical deacidification to remove all components forming sparingly soluble compounds with lime. The solvent water is used for the production for milk of lime and for their dilution to produce lime water. The lime water is treated by membranes to separate undissolved and insoluble particles. The filtrate is particle-free lime water with a constant quality. Sludge containing water from the membrane flush is recycled. No liquid residuals are produced within the process. The amount of solid residuals has been reduced by more than 80% compared to the currently used conventional lime water saturators using raw water as solvent. The process is flexible in operation, easy to automate and allows compact cubatures.