Leaching characteristics of calcium-based compounds in MSWI Residues: From the viewpoint of clogging risk. (August 2015)

• Record Type: Journal Article
• Authors: Xia, Yi; Zhang, Hua; Phoungthong, Khamphe; Shi, Dong-Xiao; Shen, Wen-Hui; Shao, Li-Ming; He, Pin-Jing
• Is Part Of: Waste management. Volume 42(2015)
• Page Start: 93
• Page End: 100
• Publication Date: 2015-08
• Subjects: Leachate collection system clogging -- pH-dependent leaching characteristic -- Leaching kinetics -- Clogging potential computation -- Calcium-based compounds; APC air pollution control -- CDR calcium dissolution ratio -- C&D construction and demolition -- HAc acetic acid -- LCS leachate collection system -- MSW municipal solid waste -- MSWIBA municipal solid waste bottom ash -- SAPCR stabilized air pollution control residues -- VFAs volatile fatty acids -- XRD X-ray diffraction; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2015.04.017
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: The leaching behavior of Ca-based compounds commonly in MSWI residues was studied. pH is the crucial factor for calcium leaching process. CaCO3 was the most sensitive to leaching temperature and Ca3 (PO4 )2 was the least. Ca leaching of MSWIBA and SAPCR attributed to CaCO3 and Ca3 (PO4 )2 respectively. Potential clogging ability of MSWI residues leachate in open air was calculated. Abstract: Leachate collection system (LCS) clogging caused by calcium precipitation would be disadvantageous to landfill stability and operation. Meanwhile, calcium-based compounds are the main constituents in both municipal solid waste incineration bottom ash (MSWIBA) and stabilized air pollution control residues (SAPCR), which would increase the risk of LCS clogging once these calcium-rich residues were disposed in landfills. The leaching behaviors of calcium from the four compounds and municipal solid waste incineration (MSWI) residues were studied, and the influencing factors on leaching were discussed. The results showed that pH was the crucial factor in the calcium leaching process. CaCO3 and CaSiO3 began leaching when the leachate pH decreased to less than 7 and 10, respectively, while Ca3 (PO4 )2 leached at pH < 12. CaSO4 could hardly dissolve in the experimental conditions. Moreover, the sequence of the leaching rate for the different calcium-based compounds is as follows: CaSiO3 > Ca3 (PO4 )2 > CaCO3 . The calcium leaching from the MSWIBA and SAPCR separately started from pH < 7 and pH < 12, resulting from CaCO3 and Ca3 (PO4 )2 leaching respectively, which was proven by the X-ray diffraction results. Based on the leaching characteristics of the different calcium compounds and the mineral phase of calcium in the incineration residues, simulated computation of their clogging potential was conducted, providing the theoretical basis for the risk assessment pertaining to LCS clogging in landfills.