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Leaching of Carbonated Air Pollution Control Residues Using Compliance Leaching Tests
Author(s) -
He PinJing,
Zhang Hua,
Shao LiMing,
Lee DuuJong
Publication year - 2006
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2005.0312
Subject(s) - leachate , leaching (pedology) , toxicity characteristic leaching procedure , hazardous waste , chemistry , pollution , environmental chemistry , environmental science , carbonation , waste management , pulp and paper industry , heavy metals , soil water , soil science , ecology , organic chemistry , biology , engineering
The leaching characteristics of air pollution control (APC) residues collected in Shanghai, China, were compared by performing three compliance leaching tests. These were the standard Chinese method for determining the leaching toxicity of solid waste (GB 5086.1‐1997), the USEPA's Toxicity Characteristic Leaching Procedure (TCLP), and the new European shake test (EN 12457‐3). In particular, behaviors of raw samples and samples that had been subjected to natural aging were compared. Both the leaching tests and natural aging substantially affected the leaching results concerning the APC residue samples. Most importantly, EN and GB tests classified the raw APC residues as hazardous, but the residues passed the TCLP test as nonhazardous. After it had been naturally aged for 720 h, however, the aged sample was classified as hazardous by the TCLP and EN tests, but as nonhazardous by the GB test. Metals that are thought to have been immobilized by carbonation were released at pH 6.3. Model calculations based on the geochemical thermodynamic equilibrium model MINTEQA2 revealed that the formation of metal carbonates did not correspond to the noted change in the leaching behaviors in the three leaching tests. Rather, the partial neutralization of alkaline ash by dissolved CO 2 changing the final pH of the leachate dominated the leaching characteristics. The leaching results showed a change in leachate pH.