Waste leachate

Sites made suitable for use by human-made physical barriers shall not be located where improper operations or maintenance of such structures could permit the waste, leachate, or gases to contact usable groundwater or surface water. 

Headspace analysis has also been used to determine trichloroethylene in water samples. High accuracy and excellent precision were reported when GC/ECD was used to analyze headspace gases over water (Dietz and Singley 1979). Direct injection of water into a portable GC suitable for field use employed an ultraviolet detector (Motwani et al. 1986). While detection was comparable to the more common methods (low ppb), recovery was very low. Solid waste leachates from sanitary landfills have been analyzed for trichloroethylene and other volatile organic compounds (Schultz and Kjeldsen 1986). Detection limits for the procedure, which involves extraction with pentane followed by GC/MS analysis, are in the low-ppb and low-ppm ranges for concentrated and unconcentrated samples, respectively. Accuracy and precision data were not reported. 

Sabel GV, Clark TP. 1984. Volatile organic compounds as indicators of municipal solid waste leachate contamination. Waste Manag Res 2 119-130. 

Ham, R.K., Boyle, W.C., Engroff, E.C., and Fero, R.L., Determining the presence of organic compounds in foundry waste leachates, in Modern Casting, American Foundrymen s Society, August 1989. 

The minimum thickness specification for an FML top liner covered with a layer of soil is 0.75 mm for an FML without a soil cover layer, the specification is 1.14 mm. An FML in a composite bottom liner system must be at least 0.75 mm thick. Even though these FML thicknesses meet U.S. EPA specifications, 0.75mm is not a suitable thickness for all FML materials. In fact, most FML materials installed at landfills are in the range of 1.50-2.50 mm in thickness. Other key factors affecting the selection of FML materials include chemical compatibility with waste leachate, aging and durability characteristics, stress and strain characteristics, ease of installation, and water vapor/ chemical permeation. 

The main selection criteria for synthetic drainage materials are high hydraulic transmissivities, or in-plane flow rates, and chemical compatibility with the waste leachate. Discussion of the chemical compatibility of synthetic liners and drainage layers is given in a later section. 

This section discusses soil liners and their use in hazardous waste landfills. The section focuses primarily on hydraulic conductivity testing, both in the laboratory and in the field. It also covers materials used to construct soil liners, mechanisms of contaminant transport through soil liners, and the effects of chemicals and waste leachates on compacted soil liners. 

Calcium bentonite, as though more permeable than sodium bentonite, has also been used for soil blends. Approximately twice as much calcium bentonite typically is needed however, to achieve a hydraulic conductivity comparable with that of sodium bentonite. One problem with using sodium bentonite, however, is its vulnerability to attack by chemicals and waste leachates, a problem that will be discussed later. 

Chemical compatibility studies with hydraulic conductivity tests must be performed over a long enough period of time to determine the full effects of the waste liquid. Termination criteria include equal inflow and outflow of liquid, steady hydraulic conductivity, and influent/effluent equilibrium. At least two pore volumes of liquid must be passed through the soil to flush out the soil water and bring the waste leachate into the soil in significant quantities. Reasonable equilibrations of the influent and effluent liquids occur when the pH values of the waste influent and effluent liquids are similar and the key organic and inorganic ions are at full concentrations in the effluent liquid. 

The chemical compatibility of an FML with waste leachate is an important material consideration. 

In silt clay soils (0-30 cm) of Isfahan, Central Iran, the amount of EDTA-extractable Zn, Cu, Pb, Ni, Cd, Co and Cr were 3.2, 1.8, 2.6, 0.6, 0.16, 0.6 and 0.8 mg/kg, respectively (Khoshgoftarmanesh and Kalbasi, 2002). Concentrations of these trace elements increased in subsoils (30-60 cm) and increased with applications of municipal waste leachate. In the surface soils of agricultural, industrial and urban regions of Isfahan, central Iran, the average DTPA-Cd was 0.09 mg/kg, and about 80% of the soil samples had less than 0.1 mg/kg DTPA-extractable Cd (Amini et al., 2005). DTPA-Cd was strongly correlated with EC in the soils. 

Khoshgoftarmanesh A.H., Kalbasi M. Effect of municipal waste leachate on soil properties and growth and yield of rice. Commun Soil Sci Plant Anal 2002 33 2011-2020. 

In Texas in 1965-1972 from uranium mine waste leachate... 

Ghasseml, M. Qulnllvan, S. Haro, M. Metzger, J. Sclnto, L, White, H, "Compilation of Hazardous Waste Leachate Data , 1983, Office of Solid Waste, U.S. Environmental Protection Agency, EPA Contract No. 68-02-3174. 

The Microtox test has been used for determination of toxicity of wastewater effluents, complex industrial wastes (oil refineries, pulp and paper), fossil fuel process water, sediments extracts, sanitary landfill, and hazard waste leachates [19]. 

Younger, P. L. 2003. Passive in situ remediation of acidic mine waste leachates progress and prospects. In Moore, H. M., Fox, H. R. Elliott, S. (eds) Land Reclamation - Extending the Boundaries. Balkema, Lisse (NL), 253-264. 

The degree of decarbonation of the waste. Leachate alkalinity is generally proportional to the degree of decarbonation. 

Caron, F., Elchuk, S. Walker, Z. H. 1996. HPLC characterization of dissolved organic matter from low-level radioactive waste leachates. Journal of Chromatography, 739, 281-294. 

Sophisticated and highly refined methods are available to detect trace levels of silver and its compounds in air, solid waste leachate, water (the medium of most concern for human exposure), food, and other environmental media. These methods can accurately measure background levels in environmental samples, as well as levels at which health effects occur. There are no known deficiencies in the analytical methods for determining silver in environmental media, and no additional analytical methods appear to be necessary. 

Gray, D. H., and Weber, W. J. (1984). Diffusional transport of hazardous waste leachate across clay barriers, Proceedings of the 7th Annual Waste Conference, Sept 11-12, Univ. ofWisconsin, Madison, 373-389. 

Table 1. Studies involving toxicity testing of wastewaters and solid waste leachates.

Table 3 (continued). Studies combining toxicity/chemical testing and sometimes integrating other disciplines to assess waters, wastewaters and solid waste leachates. 

Joutti, A., Schultz, E., Tuukkanen, E. and Vaajasaari, K. (2000) Industrial waste leachates toxicity detection with microbiotests and biochemical tests, in G. Persoone, C. Janssen and W.M. De Coen (eds.), New Microbiotests for Routine Toxicity Screening and Biomonitoring, Kluwer Academic/Plenum Publishers, New York, pp. 347-355. 

Table 5. HMBC for Municipal Solid Waste leachates from Florida Landfills.

Application examples are provided for surface waters, groundwater, and pore waters from sediments, as well as complex environmental samples including industrial wastewaters, biosolids from municipal treatment plants, hazardous wastes and waste leachates. 

The case study presented here was conducted by the Environmental Research Centre, CIMA, Faculty of Sciences, of the University of La Plata. The more frequently applied tests were those conducted with the Lactuca sativa seed germination assay, followed by the Hydra, Daphnia and Selenastrum tests. They were used for the assessment of toxicity from hazardous wastes and waste leachates, sediment pore water and sediment leachates, surface waters and groundwater. An additional test based on (3-galactosidase (in vitro-free enzyme test) inhibition, known for its sensitivity to metals (Apartin and Ronco, 2001), was also incorporated in the battery. 

It was observed that EDAR index values and intervals (Tables 2 and 4) did not change markedly with the deletion of two toxicity tests. Results of applying the EDAR index to waste samples indicate that values and ranks relate to the solubility of toxicants in aqueous phases. Based on this evaluation, wastes from photographic and X-Ray laboratories were observed to be extremely hazardous in contrast to hydrocarbon-containing waste leachates, described as either slightly hazardous or hazardous. The existence of sub-levels for an equivalent hazard description allows for better sample discrimination (e.g., Pharmaceutical solid waste leachate versus liquid waste with pesticides in Table 5). 

Food industry solid waste (leachate) 0.29 III Slightly hazardous H-D-L... 

In undertaking our search of the literature linked to bioanalytical assessment of solid waste leachates (Tab. 2), we circumscribed it to small-scale toxicity testing performed on leachates. Furthermore, we did not exclude marine bioassays, but we exclusively selected literature references involving test battery approaches (TBAs) on solid wastes (or their elutriates). As defined previously in the first chapter of this book, a TBA represents a study conducted with two or more tests representing at least two biotic levels. As also pointed out in Section 2 of this chapter, TBAs are suitable to assess hazard at different levels so as not to underestimate ecotoxicity. Nevertheless, we have not excluded from this review publications describing other types of bioassays (e.g., terrestrial bioassays, sub-cellular bioassays or those carried out with recombinant DNA (micro)organisms and biosensors), when those were part of the TBA. 

Table 2. Application of bioassays to assess ecotoxicity of (solid) waste leachates test batteries are listed in chronological order.

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