article posted 30 March 2016
Mariona Tarrago received her B.S. in Geology from University of Barcelona in 2012 and her M.S. in Mineral Resources and Geological Hazards in 2013. She is currently working towards a PhD in Earth Sciences at the University of Barcelona with the subject “Modelization of sewage sludge vitrification using a basaltic matrix”. The thesis includes establishing the compositional limits of modified basaltic compositions which are analogous to sewage sludge, characterizing their rheological behaviour and structure. Part of this research is undertaken in collaboration with the Institut de Physique du Globe de Paris.
Incorporation of P and Ca in basaltic glass: application to waste management
1,2Mariona Tarrago*, 1Maite Garcia-Valles, 1Salvador Martinez, 2Daniel R. Neuville
1. Dept. Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona. C/Martí i Franquès s/n 08028 Barcelona (Spain)
2. Institut de Physique du Globe de Paris, CNRS, Sorbonne Paris Cité, 1 rue Jussieu 75005 Paris (France)
A modified basaltic composition is used to simulate the production of glass using sewage sludge from wastewater treatment plants as a main raw material.
This composition may be used as inertization matrix for potentially toxic elements contained in different wastes. The basalt (SiO2
46.62 mol%, Al2
CaO 10.42 mol%, FeO 9.91 mol%, MgO 15.60 mol%, Na2
O 3.06 mol%, TiO2
2.00 mol%, K2
O 1.04 mol%, P2
0.27 mol%) is separately doped with P (up to 17.65 mol%) and
Ca (up to 32.25 mol%) to establish the maximum addition limit of each of them in the glass. These limits cover at least the average concentrations of P2
CaO of wastes similar to sewage sludge. The solubility of each additive in the melt is determined by the crystallization of the glass during production (using
a melting temperature of 1450 ºC).
Understanding the production process of these glasses requires an assessment of the evolution of their structure as a consequence of ion doping to explain variations
in the macroscopic properties that are essential in glassmaking, such as density, Tg and viscosity. The structural information at the atomic scale will be obtained by
Raman spectroscopy, which is sensitive to variations on medium range order of the glasses. In situ Raman spectroscopy can also give an important knowledge on the
nucleation and growth in the Ca-P-basalt as a function of temperature.
The addition of P to a basalt causes a decrease in density, and some new bands appear in the Raman spectra. The addition of Ca to a basalt causes an increase in density
and variations of the relative heights of Raman bands. We plan to discuss the changes that occur in a basaltic system when a huge proportion of P and/or Ca is added to
the glass, and how these changes can be linked between macroscopic properties and nanoscopic scale.