Kinetics of hexavalent chromium reduction in constructed wetland mesocosms

CIM Journal, Vol. 5, No. 4, 2014
A. Rodriguez-Prado
Independent Consultant, Saskatoon, Saskatchewan, Canada
R. L. Legge
Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
W. C. Lennox
Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada
P. Kuschk
Department of Environmental Biotechnology,
Helmholtz Centre for Environmental Research, Leipzig, Germany
L’utilisation de marais artificiels pour réduire chimiquement le chrome hexavalent Cr(VI) en Cr(III) des eaux usées industrielles et minières a été prouvée faisable et efficiente. L’application de la cinétique de premier ordre pour décrire le processus est simple mais, dans certain cas, il faut un modèle plus précis pour refléter le processus. Cet article étudie la faisabilité d’utiliser la cinétique de non premier ordre pour décrire le processus de réduction. Les résultats indiquent que les cinétiques de demi-ordre et de deuxième ordre décrivent adéquatement la réduction du Cr(VI) dans des mésocosmes de marais en laboratoire. La teneur en carbone organique joue un rôle pertinent, qu’il ait été rehaussé par la croissance des plantes ou qu’il ait été introduit dans l’eau d’alimentation.
Mots clés : Marais artificiels, réduction du chrome hexavalent (Cr(VI)), cinétique de réduction, traitement des eaux usées, drainage minier acide
Résumé Les étudiants, même ceux qui ont de fortes connaissances mathématiques, ont souvent de la difficulté à comprendre les concepts de la géostatistique. L’un des principaux problèmes est la relation entre la variation des valeurs des paramètres dans l’espace ou le temps et le semi-variogramme expérimental calculé. Un autre défi est de différencier entre les semi-variogrammes directionnels et omnidirectionnels et leur interprétation. Des outils interactifs ont donc été développés; ils sont basés sur le logiciel libre R dans le domaine public. L’utilisation de ces outils interactifs est limitée à des situations éducatives (c.-à-d. pour visualiser les concepts de base). Les modules interactifs sont disponibles au : www.bwk.kuleuven.be/geostatistics.
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