Volume 12, No. 3, June 2012, Pages 426-434 PDF(3.21 MB)
Metal Distribution Characteristics in a Laboratory Waste Incinerator
Chih-Ping Chang1,5, Yun-Hwei Shen1, I-Cheng Chou2, Ya-Fen Wang3, Yi-Ming Kuo2, Juu-En Chang4
1 Department of Resources Engineering, National Cheng KungUniversity, 1 University Rd., Tainan City 701, Taiwan
2 Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, 89 Wenhua 1st St., Rende Dist., Tainan City 717, Taiwan
3 Department of Bioenvironmental Engineering, Chung Yuan Christian University, 200 Chung Pei Rd., Chung Li 320, Taiwan
4 Department of Environmental Engineering, National Cheng Kung University, 1 University Rd., Tainan City 701, Taiwan
5 Environmental Resource Management Research Center, Cheng Kung University, 500 Anming Rd. Sec. 3, Annan Dist., Tainan City 709, Taiwan
The metal distribution in the emissions of a laboratory waste incinerator (LWI) was investigated. The input materials and output materials (fly ash, bottom ash, and flue gas) were analyzed to examine the transportation and transmission behavior of heavy metals.
Toxic (As, Cd, Cr, Hg, Ni, and Pb), anthropogenic (Ag, Ba, Cu, Mn, Se, and Zn) and crust (Na) elements were adopted to characterize the distribution properties of the LWI under investigation. The results indicated that Ba, Cr and Hg (80.0, 13.0 and 12.9 mg/L, respectively) were the major metals in the organic liquid waste input, and Na, and Zn (7497 and 349 mg/kg, respectively) were the major ones for medical solid waste. The Na content in the fly ash could be as high as 911574 mg/kg, and this was found to be the major Na emission source according to the emission factors. The mass of Na may be supplied using a NaOH solution injection to neutralize the acidic combustion gas, and it was found that high contents of Na in the flue gas were from the sprinkled NaOH solution. For the output materials, NaCl was found to be the major crystalline form of Na in the ash, based on the results of X-ray diffraction (XRD) patterns. The crust (Na) element was the major element in the bottom and fly ash. The toxic (As, Cr, Ni, and Pb) and anthropogenic (Se) elements were mainly distributed in the second cooling tower ash and baghouse ash in a range of 64.5%–91.9%. The average concentrations of Pb, Cd, and Hg concentrations in the flue gas were all under Taiwan’s EPA regulation standards.
Toxicity characteristic leaching procedure (TCLP) data showed that the leachability of As, Cr, Cu, Hg, and Se exceeded the EPA’s regulations. It is thus suggested that the ash should be treated by further elutriation or vitrification processes to reduce the TCLP levels in the final products.
Incineration; Metal distribution; Laboratory waste; Solid waste.