title: Optimization of the preparation conditions of ceramic products using drinking water treatment sludges.
abstract: The aim of this work is to optimize, via Response Surface Methodology, the values of the main process parameters for the production of ceramic products using sludges obtained from drinking water treatment in order to valorise them. In the first experimental stage, sludges were collected from a drinking water treatment plant for characterization. In the second stage, trials were carried out to elaborate thin cross-section specimens and fired bricks following an orthogonal central composite design of experiments with three factors (sludge composition, grain size and firing temperature) and five levels. The optimization parameters (Y(1)=shrinking by firing (%), Y(2)=water absorption (%), Y(3)=density (g/cm(3)) and Y(4)=compressive strength (kg/cm(2))) were determined according to standardized analytical methods. Two distinct physicochemical processes were active during firing at different conditions in the experimental design, preventing the determination of a full response surface, which would allow direct optimization of production parameters. Nevertheless, the temperature range for the production of classical red brick was closely delimitated by the results; above this temperature, a lightweight ceramic with surprisingly high strength was produced, opening possibilities for the valorisation of a product with considerably higher added value than what was originally envisioned.
authors.affiliation: Instituto de Ingenieria, UNAM, Coordinacion de Ingenieria Ambiental, Ciudad Universitaria, Coyoacan, Mexico, D. F. RRamirezZ@iingen.unam.mx
authors.forename: R M Ramirez
authors.initials: RM
authors.lastname: Zamora
authors.forename: F Espesel
authors.initials: FE
authors.lastname: Ayala
authors.forename: L Chavez
authors.initials: LC
authors.lastname: Garcia
authors.forename: A Duran
authors.initials: AD
authors.lastname: Moreno
authors.forename: R
authors.initials: R
authors.lastname: Schouwenaars
mesh_terms: D000042:Absorption; D002516:Ceramics / Q000138:chemical synthesis* / Q000737:chemistry; D019245:Compressive Strength; D003247:Conservation of Natural Resources / Q000379:methods*; D004326:Drinking; D010087:Oxides / Q000032:analysis; D010316:Particle Size; D012722:Sewage / Q000737:chemistry*; D013696:Temperature; D018508:Water Purification; D014881:Water Supply
chemical_list: D010087:Oxides; D012722:Sewage