Environment Leaching Characteristics Of Heavy Metals In Waste PDP Back Panel Glass

Waste Electric and Electronic Equipment (WEEE) is the most rapidincrement solid waste in decennium, among it, display screens from wastecomputer and TV have the high proportion. Waste Plasma Display Panel（PDP）back glass has a great quantity of heavy metals, such as Zn, Cu and Ag.Unreasonable dispose may lead to environmental contamination. Therefore, thedispose of waste PDP back glass is a hotspot of waste treatment. This paperreports on PDP back glass in the way of toxic leaching, chemical form andbiological effectiveness, which investigate the environment leachingcharacteristics of waste PDP back glass.The environment leaching characteristics of heavy metals in waste PDPback glass was studied using the methods of GB, toxicity characteristic leachingprocedure (TCLP), Japan and Italy Solid waste toxic leaching procedure, BCR’sthree stage(BCR3) extraction procedures, BCR’s four stage(BCR4) extractionprocedures and BCR’s five stage(BCR5) extraction procedures, DTPA&EDTAbioavailability extraction procedures. The results were significant in scientificand practical value, and the following creative results have been achieved:1. Waste PDP back glass should be defined to hazardous wastes. Aftercomparison, TCLP is more appropriate than other three methods to investigatethe toxic leaching of waste PDP back glass.2. The chemical form results show that the heavy metal extraction effectwith BCR3procedures was steadier than that with BCR4procedures and withBCR5procedures. There are significant differences in chemical formdistributions of some heavy metals in waste PDP glass. Three methods all thinkNi not be detected, the chemical form of Ag, Ba and As in waste PDP glass existmainly in residual forms. The percentage of exchangeable and weak acid solubleform with BCR3procedures and BCR5procedures or exchangeable metals andmetals associated to carbonates form with BCR4procedures of Cu are low, whichhas little risk for the environment. The estimates of the chemical form of Zn withBCR3and BCR4&BCR5are inconformity, metals associated to oxides of Fe andMn forms of Zn is the main form in waste PDP glass with BCR4procedures andBCR5procedures, while the percentage of exchangeable and weak acid soluble form of Zn is the highest with BCR3procedures, the harm of Zn from waste PDPglass could be high.3. The leaching content of Zn, Cu and Ba in waste PDP back glass areagreed, while the higher leaching toxicity rest with exchangeable&weak acidsoluble fraction and reducible fraction. The leaching content of Ag exists mainlyfrom residual forms. The estimates of As with BCR3-TCLP&BCR5-TCLP andBCR4-TCLP are inconformity, Carbonate bound of Zn is the main in waste PDPglass with BCR4-TCLP and BCR3-TCLP&BCR5-TCLP, while the residualforms of As is the main.4. The biological extracted effectively quantity of Zn in waste PDP backglass is higher, which displays that waste PDP have higher potential biologictoxicity. The content of biological effectiveness with Cu and Ag are low, whichare difficult to absorb with plants; the absolute biological extracted effectivelyquantity of Ba and As in waste PDP back glass are higher; the content of Ni isnot detected.