Metal Distribution Characteristics in a Laboratory Waste Incinerator

Abstract

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.

High-Temperature Cleaning for Chlorine-Containing Coal Gas by Supported Manganese Oxide Sorbent

“…Among them, absorption by sorbents provides a relatively direct and convenient way to remove the contaminants resulted from coal gasification. Popular candidates for desulfurization include Ca-based sorbent (Li et al, 2007), Fe-based sorbent (Ko et al, 2006), Mn-based sorbent (Bakker et al, 2003;Ko et al, 2005), Zn-based sorbent (Bu et al, 2008), and mixed metal oxide sorbent (Tseng et al, 2008;Lou et al, 2009;Chang et al, 2012). As for dechlorination, absorption by Ca-based sorbents has always been a prevalent choice (Yan et al, 2003;Partanen et al, 2005).…”

Polychlorinated Dibenzo-p-dioxin and Dibenzofuran (PCDD/F) Emission Behavior during Incineration of Laboratory Wastes. Part 2: PCDD/F Profiles and Characteristics of Output Materials

“…Previous studies reported that PCDD/Fs mainly form in the temperature range of 250 to 350°C, which is the case in the first quenching towers (Hajizadeh et al, 2011;Jansson and Andersson, 2011). According to our previous study, metals which vaporized as the particulate phase reacted with Cl to form chloride in flue gas (Chang et al, 2012). During this stage, metal chloride plays an important role in catalyzing the formation of PCDD/Fs (Lu et al, 2007;Nganai et al, 2011).…”

Experimental and Molecular Simulation Study for the Preparation of Ordered Mesoporous Carbons

“…The X-ray powder diffraction patterns of OMCs were measured using a D8 diffractometer (Bruker, Germany) with Ni-filtered Cu-Ka radiation between 0.6° and 6° for small-angle X-ray diffraction and between 10° and 90° for wide-angle X-ray diffraction (Chang et al, 2012;Grigoriu et al, 2012). The N 2 adsorption-desorption isotherms were measured using a ASAP2010 (Micromeritics, USA) system, and the pore size distribution curves were determined from the adsorption branch of the isotherm.…”