Leaching of Lead from Computer Printed Wire Boards and Cathode Ray Tubes by Municipal Solid Waste Landfill Leachates

Abstract

The proper management of discarded electronic devices (E-waste) is an important issue for solid waste professionals because of the magnitude of the waste stream and because these devices often contain a variety of toxic metals (e.g., lead). While recycling of E-waste is developing, much of this waste stream is disposed in landfills. Leaching tests are frequently used to characterize the potential of a solid waste to leach when disposed in a landfill. In the United States, the Toxicity Characteristic Leaching Procedure (TCLP) is used to determine whether a solid waste is a hazardous waste by the toxicity characteristic. The TCLP is designed to simulate worse-case leaching in a landfill environment where the waste is co-disposed with municipal solid waste (MSW). While the TCLP is a required analysis from a regulatory perspective, the leachate concentrations measured may not accurately reflect the concentrations observed under typical landfill conditions. Another method that can be performed to assess the degree a pollutant might leach from a waste in a landfill is to use actual landfill leachate as the leaching solution. In this study, two lead-containing components found in electronic devices (printed wire boards from computers and cathode ray tubes from computers and televisions) were leached using the TCLP and leachates from 11 Florida landfills. California's Waste Extraction Test (WET) and the Synthetic Precipitation Leaching Procedure were also performed. The results indicated that the extractions using MSW landfill leachates resulted in lower lead concentrations than those by the TCLP. The pH of the leaching solution and the ability of the organic acids in the TCLP and WET to complex with the lead are factors that regulate the amount of lead leached.

Leaching Assessments of Hazardous Materials in Cellular Telephones

“…Previous e-waste studies (e.g., [13][14][15][16] have shown that Pb exceeds the regulatory standards according to TCLP, although at a much lower concentration than the average 87.42 mg L -1 reported in the present study. This discrepancy is likely due to two factors.…”

“…Several studies have used various leaching procedures to characterize e-waste (13)(14)(15)(16), and they demonstrate that Pb is the metal that most frequently exceeds regulatory thresholds for hazardous waste at all jurisdictional levels. Therefore, regulatory agencies have focused on replacing Pb in electronic products (2).…”

Lead recovery and the feasibility of foam glass production from funnel glass of dismantled cathode ray tube through pyrovacuum process

“…It may be concluded that lead concentration is inversely proportional to its lead recovery rate. Third, the concentrations that exceed the regulatory limit of 5.0 mg/L for TCLP lead [25,26] all have a lead recovery rate lower than 96%, as seen in Table 3. Thus, for safe treatment of funnel glass, it is necessary to obtain a relative higher lead recovery rate, such as higher than 96%, to meet the TCLP lead threshold.…”

High levels of heavy metals in rice (Oryzasativa L.) from a typical E-waste recycling area in southeast China and its potential risk to human health

“…Hundreds of small and open specialized E-waste recycling shelters or yards appear in this area. Many toxic ingredients such as lead, cadmium, beryllium, mercury, polychlorinated biphenyls and brominated flame retardants contained in these Ewastes, (Schmidt, 2002;Soderstrom and Marklund, 2002;Jang and Townsend, 2003;Wong et al, 2007) may enter into the environment and impose great threat to human health regardless of occupational and environmental exposure. The unregulated processing of E-waste usually recovers gold and other valuable metals by applying some simple techniques such as burning, melting, using acid chemical bath, and so on.…”