Increased sustainability of softening by producing pure calcite pellets for reuse

B Hofs, ET Baars, LJ Palmen, JA Elings, L.J. Kors, Onno Kramer, H Koppers, Jan Peter van der Hoek

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientific

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About 50% of the drinking water in the Netherlands is centrally softened by the drinking water companies in a process known as pellet softening. In this process a base and seeding material are mixed in an upflow reactor, where subsequently CaCO3 precipitates on a seed core as pellets. The seeding material is usually sand, but recently CaCO3 was introduced as seeding material at several full scale plants. The pure calcite pellets that are produced as a by-product in these plants can be reused as seeding material, after grinding and sieving part of the produced pellets. The main advantages of this reuse are an expected significant decrease of the ecological footprint of both calcite as raw material and the drinking water treatment plants using pellet softening, and increased valorisation of the pellets. However, the handling and processing of the pellets and seeding material should be such, that microbiological and chemical contamination risks of the drinking water are negligible. This research shows that grinded and sieved CaCO3 outperforms commercial CaCO3 and that microbiological risks can be adequately controlled.
Original languageEnglish
Title of host publicationAIWW Conference
Subtitle of host publicationIntegrated Solutions for a Circular Economy and Resilient Cities
Number of pages2
Publication statusPublished - 2015
EventAmsterdam international water week 2015 conference - Amsterdam, Netherlands
Duration: 2 Nov 20156 Nov 2015


ConferenceAmsterdam international water week 2015 conference
Abbreviated titleIWW2015


  • calcium carbonate
  • precipitation
  • pellet softening


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