An Opportunity for Recycling Semi-dry Scrubber Residues Directly from Municipal Solid Waste Incineration Plants without Concern of Leaching Toxicity

摘要

The leaching behaviors of heavy metals from semi-dry scrubber (SDS) residues of municipal solid waste incineration (MSWI) plants are re-investigated. The most leachable heavy metals in semi-dry scrubber residues from municipal solid waste incinerators are found to be chromium ions (Cr(Ⅲ) and Cr(Ⅵ)), but neither lead nor cadmium. Both of the leachabilities of Cr(Ⅲ) and Cr(Ⅵ) in MSWI scrubber residue are a function of the CaO/Al_2O_3 ratio of residues. The pH-dependent leaching behaviors are only observed in the case of Cr(Ⅲ), but not for Cr(Ⅵ). Our results show that it is worth recycling SDS residues which possess a lower chemical composition ratio of CaO/Al_2O_3, in order to reduce the potential risk of toxic leaching of chromium species.