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Chemical clogging and evolution of head losses in steel slag filters used for phosphorus removal

Dominique Claveau-Mallet and Yves Comeau

Article (2020)

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Cite this document: Claveau-Mallet, D. & Comeau, Y. (2020). Chemical clogging and evolution of head losses in steel slag filters used for phosphorus removal. Water, 12(6). doi:10.3390/w12061517
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Abstract

The objective of this study was to propose a conceptual model of clogging in alkaline granular filters. Two slag columns were operated for 600 days and monitored using piezometers and tracer tested at regular intervals. The type of influent (organic or inorganic) affected the loss of effective porosity in the filters. Well organized and loose crystal structures were observed by scanning electron microscopy in columns with inorganic and organic influents, respectively. It was postulated that the formation of crystals in unorganized structures results in confined voids that are not accessible for water flow, thus accelerating porosity loss. The effect of the combination of chemical clogging and biofilm on the porosity loss is higher than the effect of these two factors separately. The Kozeny-Carman equation for hydraulic conductivity could not efficiently predict the evolution of head losses in the column fed with an inorganic influent. The crystal structure and connectivity in the presence of homogeneous or heterogeneous precipitation are concepts that could improve predictions of hydraulic conductivity. The results of this study highlighted the importance of the inlet zone on the development of pressure head in alkaline granular filters. Future research on clogging should focus on precipitation mechanisms in the inlet zone and on the design of the feeding system.

Uncontrolled Keywords

PHREEQC; calcite; hydroxyapatite; calcium carbonate; precipitation; wastewater treatment; porosity; alkaline granular filters

Open Access document in PolyPublie
Subjects: 1400 Génie minier et minéral > 1400 Génie minier et minéral
1500 Génie de l'environnement > 1501 Qualité de l'eau, pollution
1500 Génie de l'environnement > 1502 Traitement des eaux usées
Department: Département des génies civil, géologique et des mines
Research Center: Non applicable
Funders: CRSNG/NSERC, MITACS Accelerate program, Bionest, ArcelorMittal, Harsco Minerals, AgroÉnergie, GHD Consulting, Ressources aquatiques du Québec (RAQ), NORDIKEau
Grant number: 476673-14, IT09967
Date Deposited: 16 Jul 2020 17:41
Last Modified: 17 Jul 2020 01:20
PolyPublie URL: https://publications.polymtl.ca/5307/
Document issued by the official publisher
Journal Title: Water (vol. 12, no. 6)
Publisher: MDPI
Official URL: https://doi.org/10.3390/w12061517

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