Effect of improving flue gas cleaning on characteristics and immobilisation of APC residues from MSW incineration.
The flue gas cleaning system of a MSW incinerator with a capacity of 350 kt/year was changed to improve the HCl elimination efficiency. Instead of the semi-wet operating spray reactor and subsequent baghouse, a two-step wet flue gas cleaning was added behind the baghouse. Elemental composition, X-ray powder diffraction patterns and TGA measurements showed that the resulting APC residue was totally different from the former residue. As a consequence, leaching characteristics of both residues also differed and another treatment was required prior to disposal. For the former residue, mainly leaching of Pb (>100 mg/l), necessitated treatment prior to landfilling. The lower alkalinity of the new residue resulted in a leachate pH of 9.7 and a Pb concentration of 0.8 mg/l. The leachate pH of the former residue was 12.4. The leaching of Pb and Zn increased above 100 mg/l when immobilising the new residue with cement. Better results were obtained when immobilising with micro silica. The high CaCl2 x 2H2O content of the new residue brought along clogging of the bag filter system. Adding 1.4% of CaO (or 1.9% of Ca(OH)2) to the residue already improved these inconveniences but again significantly changed the leaching behaviour of the residue.
Geysen
D
D
Public Waste Agency of Flanders, OVAM, Stationsstraat 110, B-2800 Mechelen, Belgium. daneel.geysen@ovam.be
Vandecasteele
C
C
Jaspers
M
M
Brouwers
E
E
Wauters
G
G
D002119:Calcium Carbonate / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry; D002484:Cementation; D004787:Environmental Pollution / Q000517:prevention & control*; D005740:Gases; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D019216:Metals, Heavy / Q000032:analysis*; D010087:Oxides / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D012037:Refuse Disposal / Q000379:methods*; D012822:Silicon Dioxide / Q000737:chemistry
D017610:Calcium Compounds; D005740:Gases; D019216:Metals, Heavy; D010087:Oxides; D010710:Phosphates; D012822:Silicon Dioxide; C016538:lime; D002119:Calcium Carbonate; D002126:Calcium Hydroxide