Impact of electronic waste disposal on lead concentrations in landfill leachate

Lead is the element most likely to cause discarded electronic devices to be characterized as hazardous waste. To examine the fate of lead from discarded electronics in landfills, five columns were filled with synthetic municipal solid waste (MSW). A mix of electronic devices was added to three columns (6% by weight), while two columns served as controls. A sixth column contained waste excavated from an existing MSW landfill. Leachate quality was monitored for 440 days. In columns with the synthetic waste, leachate pH indicated that the simulated landfill environment was characteristic of the acid phase of waste decomposition; lead leachability should be greater in the acid phase of landfill degradation as compared to the methanogenic phase. Lead concentrations ranged from 7 to 66 microg/L in the columns containing electronic waste and ranged from < 2 to 54 microg/L in the control columns. Although the mean lead concentrations in the columns containing electronic devices were greater than those in the controls, the difference was not found to be statistically significant when comparing the data sets over the entire monitoring period. Lead results from the excavated waste column suggest that lead concentrations in all columns will decrease as the pH increases toward more neutral methanogenic conditions.