NEW REMINERALIZATION PROCESS USING MICRONIZED CALCITE AS A SUSTAINABLE ALTERNATIVE TO THE LIME DOSING SYSTEM

摘要

Desalinated and naturally soft water is corrosive because of its low pH value and lack ofminerals, and therefore requires post-treatment for water stabilization and corrosion control.Conventional water remineralization can be achieved either by calcite contactors or lime dosingsystems. Both of these techniques present some drawbacks for large desalination plants: largefootprint of the filtration beds for the calcite contactors, and operating difficulties, e.g. clogging,turbidity problems and large volumes of sludge, for the lime systems.In order to offer a more sustainable and safer alternative to the lime dosing system, Omya hasdeveloped a remineralization process using micronized calcium carbonate, called Omyaqua®Remineralization Process. The first pilot unit (Remin PU1) is fully automated, containerizedprocess (standard 40’ container), with a full capacity of 100 m3/day and remote monitoringsystem. Producing final water using the Remin PU1 to the customer quality specifications wasdemonstrated during two long-term site trials during which the following parameters could beachieved: alkalinity increase between 50 – 70 mg/L as CaCO3, turbidity < 0.5 NTU, LSI valuebetween -0.5 to +0.5.The completed and comprehensive testing phase has offered promising perspectives for futurelarge scale applications using micronized calcium carbonate either for the construction of newremineralization plants or possible retrofit of current lime systems. Engineering design iscurrently on the way for a desalination plant of 100’000 m3/d as nominal size.