Evaluation of heavy metals in hazardous automobile shredder residue thermal residue and immobilization with novel nano-size calcium dispersed reagent.
This study was conducted to synthesize and apply a nano-size calcium dispersed reagent as an immobilization material for heavy metal-contaminated automobile shredder residues (ASR) dust/thermal residues in dry condition. Simple mixing with a nanometallic Ca/CaO/PO4 dispersion mixture immobilized 95-100% of heavy metals in ASR dust/thermal residues (including bottom ash, cavity ash, boiler and bag filter ash). The quantity of heavy metals leached from thermal residues after treatment by nanometallic Ca/CaO/PO4 was lower than the Korean standard regulatory limit for hazardous waste landfills. The morphology and elemental composition of the nanometallic Ca/CaO-treated ASR residue were characterized by field emission scanning election microscopy combined with electron dispersive spectroscopy (FE-SEM/EDS). The results indicated that the amounts of heavy metals detectable on the ASR thermal residue surface decreased and the Ca/PO4 mass percent increased. X-ray diffraction (XRD) pattern analysis indicated that the main fraction of enclosed/bound materials on ASR residue included Ca/PO4- associated crystalline complexes, and that immobile Ca/PO4 salts remarkably inhibited the desorption of heavy metals from ASR residues. These results support the potential use of nanometallic Ca/CaO/PO4 as a simple, suitable and highly efficient material for the gentle immobilization of heavy metals in hazardous ASR thermal residue in dry condition.
Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan 680-749, Republic of Korea.
Chi-Hyeon
CH
Lee
Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan 680-749, Republic of Korea.
Nguyen Thi Thanh
NTT
Truc
Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan 680-749, Republic of Korea. Electronic address: bklee@ulsan.ac.kr.
Byeong-Kyu
BK
Lee
Department of Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatsuka-Cho Shobara City, Hiroshima 727-0023, Japan.
Yoshiharu
Y
Mitoma
Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan 680-749, Republic of Korea. Electronic address: srireddys@ulsan.ac.kr.
Srinivasa Reddy
SR
Mallampati
D001336:Automobiles; D017610:Calcium Compounds / Q000737:chemistry*; D060729:Coal Ash / Q000737:chemistry; D004391:Dust; D015386:Hazardous Substances / Q000032:analysis*; D017745:Incineration; D019216:Metals, Heavy / Q000032:analysis*; D049329:Nanostructures / Q000737:chemistry*; D056910:Republic of Korea
D017610:Calcium Compounds; D060729:Coal Ash; D004391:Dust; D015386:Hazardous Substances; D019216:Metals, Heavy
ASR thermal residue; Hazardous waste; Heavy metals; Immobilization; Nanometallic Ca/CaO; Solvent-free synthesis