Hillier, Stephen
- Department of Soil and Environment, Swedish University of Agricultural Sciences
- The James Hutton Institute
Abstract
Polluted soils are a serious environmental risk worldwide and consist of millions of tons of mineral waste to be treated. In order to ensure their sustainable management, various remediation options must be considered. Hydraulic binder treatment is one option that may allow a stabilisation of pollution and thus offer a valorisation as secondary raw materials rather than considering them as waste. In this study, we focused on sulphate-polluted soil and tested the effectiveness of several experimental hydraulic binders. The aim was to transform gypsum into ettringite, a much less soluble sulphate, and therefore to restrict the potential for sulphate pollutant release. The environmental assessment of five formulations using hydraulic binders was compared to the gypsiferous soil before treatment (contaminated in sulphate). The approach was to combine leaching tests with mineralogical quantifications using among others thermogravimetric and XRD methods. In the original soil and in the five formulations, leaching tests indicate sulphate release above environmental standards. However, hydraulic binders promote ettringite formation, as well as a gypsum content reduction as observed by SEM. The stabilisation of sulphates is, however, insufficient, probably as a result of the very high content of gypsum in the unusual soil used. The mineralogical reactions highlighted during the hydration of hydraulic binders are promising; they could pave the way for the development of new industrial mixtures that would have a positive environmental impact by allowing reuse of soils that would otherwise be classified as waste.
Keywords
Sulphate leaching; Gypsiferous soils; Mineralogical quantifications; Sulphoaluminate ALPENAT (R) binder; SEM observations
Published in
Environmental Science and Pollution Research
2018, volume: 25, number: 23, pages: 22977-22997
Publisher: SPRINGER HEIDELBERG
SLU Authors
Global goals (SDG)
SDG6 Clean water and sanitation
SDG12 Responsible consumption and production
UKÄ Subject classification
Soil Science
Publication identifier
- DOI: https://doi.org/10.1007/s11356-018-2376-5
Permanent link to this page (URI)
https://res.slu.se/id/publ/96392