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Valorization of sludge from a wastewater treatment plant by glass-ceramic production

The study of the nucleation and crystal growth of a glass made from sewage sludge is the base for the production of a new glass-ceramic material to render the potentially harmful elements of the sludge inert. Two mineral phases crystallize during thermal treatments of sludge glass: magnetite (starts growing below 700C and up to above 1000C) and plagioclase (starts growing at 850C and up to 925C). Magnetite is present either as individual crystals or as polycrystalline aggregates. Plagioclase grows as individual crystals reaching sizes up to 250nm. During devitrification, magnetite is initially intergrown with plagioclase and then it is expelled to the grain boundaries at temperatures above 800C. In the glass-ceramic, plagioclase aggregates (90wt%) longer than 50m are intergrown with magnetite crystals (10wt%) of less than 1m in diameter. The concentrations of potentially toxic elements in both the glass and the glass-ceramic leachates are low enough for them to be considered inert.

» Author: M. Tarrago, M. Garcia-Valles, M.H. Aly, S. Martnez

» Reference: Ceramics International, Volume 43, Issue 1, Part B

» Publication Date: 01/01/2017

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This project has received funding from the European Unions Horizon 2020 research and innovation program under grant agreement N 690103