Increased sustainability of softening by producing pure calcite pellets for reuse

Conference paper (2015)

Authors

B Hofs KWR Water Research Institute
ET Baars Waternet
LJ Palmen KWR Water Research Institute
JA Elings Reststoffenunie Waterleidingbedrijven
L.J. Kors Waternet
O.J.I. Kramer Waternet, Sanitary Engineering - CEG
H Koppers Reststoffenunie Waterleidingbedrijven
J.P. van der Hoek Sanitary Engineering - CEG
Research Group
Sanitary Engineering (CEG) (TU Delft)
Copyright: © 2015 B Hofs, ET Baars, LJ Palmen, JA Elings, L.J. Kors, O.J.I. Kramer, H Koppers, J.P. van der Hoek
Precipitation Calcium carbonate Pellet softening
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Published Date

2015

Language

English

Reuse Rights

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Faculty

Civil Engineering & Geosciences

Department

Water Management

Research Group

Sanitary Engineering

Abstract

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.