title: Low frequency ultrasound-assisted leaching of sewage sludge for toxic metal removal, dewatering and fertilizing properties preservation.
abstract: The aim of this research was to evaluate the efficiency of an ultrasonication process in combination with METIX-AC technology, a chemical process, for metal removal and dewatering ability, with preservation of fertilizing properties of sewage sludge. Waste activated sludge samples having a total solids concentration of 4 and 20 g L(-1), were enriched with Cu and Zn in order to exceed the limiting values recommended by Québec regulation for sludge valorization. Ultrasonication was applied at low frequency (22 kHz) at specific energies ranging from 180 to 66,000 kJ kg(-1) of dry sludge. Ultrasound-assisted leaching rates and yields were similar to chemical leaching alone for Zn, whereas solubilisation was reduced for Cu, regardless the specific energy. Fertilizing properties preservation and dewatering ability were similar in ultrasound-assisted leaching, compared to chemical leaching alone. These trends were mainly attributed to the changes of metal speciation, particle size and morphology during ultrasonication, in addition to untreated sludge properties.
authors.affiliation: Laboratoire de Chimie Moléculaire et Environnement, Université de Savoie, Savoie Technolac 73376 Le Bourget du Lac, France. samuel.delarochebrochard@hotmail.fr
authors.forename: Samuel
authors.initials: S
authors.lastname: de La Rochebrochard
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Naffrechoux
authors.forename: Patrick
authors.initials: P
authors.lastname: Drogui
authors.forename: Guy
authors.initials: G
authors.lastname: Mercier
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Blais
mesh_terms: D003300:Copper / Q000302:isolation & purification* / Q000633:toxicity; D004785:Environmental Pollutants / Q000302:isolation & purification* / Q000633:toxicity; D005308:Fertilizers; D007700:Kinetics; D010316:Particle Size; D012722:Sewage / Q000737:chemistry*; D014465:Ultrasonics / Q000379:methods*; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000302:isolation & purification* / Q000633:toxicity
chemical_list: D004785:Environmental Pollutants; D005308:Fertilizers; D012722:Sewage; D014867:Water; D003300:Copper; D015032:Zinc