Wet extraction of heavy metals and chloride from MSWI and straw combustion fly ashes.
Fly ash residues from combustion often do not meet the criteria neither for reuse as construction materials nor landfilling as non-hazardous waste, mainly because of the high concentration of heavy metals and chlorides. This work aimed to technically evaluate an innovative wet treatment process for the extraction of chloride (Cl(-)), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) from fly ashes from a municipal solid waste incineration (MSWI) plant and from a straw combustion (SC) facility. Factors investigated were liquid/solid (L/S) ratio, full carbonation (CO(2) treatment), influence of pH and leaching time, using a two-level full factorial design. The most significant factor for all responses was low pH, followed by L/S ratio. Multiple linear regression models describing the variation in extraction data had R(2) values ranging from 58% to 98%. An optimization of the element extraction models was performed and a set of treatment conditions is suggested.
Aguiar del Toro
M
M
Hamburg University of Technology, Institute of Environmental Technology and Energy Economics, Eissendorfer Street 40, D-21073 Hamburg, Germany.
Calmano
W
W
Ecke
H
H
D002244:Carbon / Q000737:chemistry*; D002245:Carbon Dioxide / Q000032:analysis; D005591:Chemical Fractionation / Q000379:methods*; D002712:Chlorides / Q000032:analysis / Q000302:isolation & purification*; D060729:Coal Ash; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D007700:Kinetics; D019216:Metals, Heavy / Q000032:analysis / Q000302:isolation & purification*; D008956:Models, Chemical; D052638:Particulate Matter / Q000737:chemistry*; D018505:Waste Management / Q000379:methods*
D002712:Chlorides; D060729:Coal Ash; D019216:Metals, Heavy; D052638:Particulate Matter; D002245:Carbon Dioxide; D002244:Carbon