Leachate quality

TABLE 25-72 Typical Leachate Quality of Municipal Waste... 

Physical and chemical tests of the final product may need to address two concerns (1) whether the solidified waste exhibits any RCRA defined toxicity characteristics or could be delisted and (2) the potential long term fate of treated materials in the disposal environment. Three tests are available which address the first concern. These are the Extraction Procedure (EP Tox) (40 CFR 261, Appendix II, 1980) and the Toxicity Characteristic Leaching Procedure (TCLP) (40 CFR 261, Appendix II, 1986), and the Multiple Extraction Procedure Test (40 CFR 261, Appendix II, January 1989). It is important to note that these tests are not indicators of expected leachate quality but of potentials. A solidified product which cannot pass the appropriate test (EP Tox or TCLP) would be subject to classification as a hazardous waste. 

The decomposition of solid urban waste in landfills is essentially a result of microbiological processes and, therefore, the production of biogas and leachate are both directly related to the activity of microorganisms. It has been demonstrated that large variations in leachate quality exist for different landfills, but also at different locations within the same landfill.6... 

Ehrig, H.J., Leachate Quality. In Christensen, T.H., Cossu, R., Eds., Sanitary Landfilling Process, Technology and Environmental Impact, Academic Press, London, 1989, pp. 213-229. 

Chemical compatibility tests using U.S. EPA Method 909040 should always be performed for hazardous waste sites, but some municipal waste sites also contain hazardous, nondegradable materials. U.S. EPA conducted a 5-year study of the impact of municipal refuse on commercially available liner materials and found no evidence of deterioration within that period. However, in a current study of leachate quality in municipal landfills, the Agency has discovered some organic chemical constituents normally found in hazardous waste landfill facilities. Apparently, small quantities of household hazardous waste enter municipal sites or are disposed of as small quantity generator wastes. As a result of these findings, U.S. EPA developed a position on the need for chemical compatibility tests for thousands of municipal waste disposal sites. 

In summary, leachates contain a variety of compounds (dissolved organic matter, inorganic compounds, heavy metals, and XOCs), due to the mixed nature of the waste in landfills. The spatial variability of the leachate quality is significant, and this can affect the leaching pattern from the landfill and the resulting plumes. A landfill should be seen as a complex source, which is expected to last for decades or even centuries. 

In addition to iron, other elements such as nickel, aluminum, manganese, copper, zinc, and cobalt must be considered. In every case, the behavior is the same. When acidities are low, the concentrations of these elements in the leachaates are also low. Again, control of the pH is a key to control the leachate quality. More important, however, the limestone slurry treatment maintained acceptable effluent quality for several months. 

Sposito, G., Page, A. L., and Frink, M. E. (1980). Effects of Acid Precipitation on Soil Leachate Quality Computer Calculations, Environmental Research Laboratory, U.S. Environmental Protection Agency, Corvallis, OR. 

Reinhar D.R., Grosh C. J. Analysis of Florida MSW Landfill Leachate Quality University of Central Florida Civil and Environmental Engineering Department March 31 1997 Report 97-3. 

From a disposal standpoint, the primary item of interest is the chemical composition of the leachate generated from a waste. We can see from Table 4 that leachate quality from waste type is not unique. Both the local climate and operational practices heavily influence leachate chemical composition. This also varies with time. The time-quality curve is somewhat bell-shaped. 

Rees, J.F. (1982) Landfill management and leachate quality. Effluent Water TreatJ., 22,457. 

Transport for Treatment The using service will determine the method of leachate disposal. Therefore, requirements for transporting leachate should be a part of that decision process. d. Leachate Treatment (1) Before a treatment plan can be formulated, the quantity and quality of leachate should be determined. Factors which influence leachate quality include ... 

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