TCLP-leachable

TCLP LEACHABLE METAL CONCENTRATIONS OF CHEMFIX TREATED AND UNTREATED SAMPLES... 

The data shows an immediate decrease (the difference between untreated and 0 hours after treatment) in the TCLP leachable metals concentration for all seven metals. This indicated that the metals were bound immediately upon being treated. There would be no threat for contaminant leaching during the period it took for the CHEMFIX product to physically solidify. In addition, the TCLP leachable metal concentrations of those samples that were not allowed to cure (0 hours after treatment) all passed the TCLP regulatory limits. Therefore immediately after treatment the material can be classified as non-hazardous. 

A solid waste is considered hazardous if it is either a listed waste or a characteristic waste. Listed wastes include a list of specific processes that generate a waste and a list of discarded commercial chemical products. There are four hazardous waste characteristics ignitability, corrosivity, reactivity, and toxicity. The last refers to the leachability of a waste and the resultant toxicity in the groundwater using the analytical method referred to as toxicity characteristic leaching procedure (TCLP). A list of substances included under TCLP is shown in Table 1. 

A specification was drawn up for a pilot recycling plant (250 tons/year) that would meet German safety and environmental standards, but the plant was not constructed because the quantity of returned batteries was insufficient to support it. Analyses of solution from laboratory-scale recycling were carried out for chromium, which is regulated for toxieity, and levels were found to be below EPA limits. TCLP tests on cells also show amounts of leachable chromium that are within EPA standards. 

The solubility product values for the Pb5(P04)3X may be as low as lO , effectively removing the Pb. Pyromorphite (Pb5(P04)3X) is highly stable, and Pb fixed there is only very poorly leachable or bioavailable (84). In addition to remediating Pb, the CMC-vivianite nanoparticles can also be used to immobilize Cu(II) in situ (83). Treatment of Cu-contaminated acidic, neutral, or calcareous soils with the CMC-vivianite nanoparticles resulted in 58%, 50%, and 78% reductions in the TCLP extraction results, demonstrating the value of this technology. 

For applications in the rain trap system, the results of the EPA s toxicity characterization leaching procedure (TCLP) indicate that none of the tire products tested exceeds proposed TCLP regulatory levels. Most compounds detected are found at trace levels, (near method detection limits), from 10 to 100 times less than TCLP regulatory limits and U.S. EPA drinking water standard maximum contaminant level (MCL) values. The Florida Department of Environmental Regulation released its final report on tire teachability in potential usage environments. The study, which evaluates the leachability of shredded tires in different aquatic environments, finds that scrap tires pose no harmful effects when used in applications that are above the water table [14]. 

Although still in its beginning, simple leaching tests are now employed by agencies for routine use to monitor mobile" or acid-soluble parts of metals, e.g. in solid residues, in addition to total concentrations (see Hirner, Chap. 3 and Forstner, Chap. 11). In a first attempt, the chemical extraction of solid waste material with distilled water or weak acids (i.e. 0.1 HCl) has become a standard procedure when assessing the initial leachability of metals in hazardous waste materials (cf German DIN 38414-S4 or US-EPA TCLP-leaching test see also Forstner 1993). 

The flocculation reactions described above attach Fe or A1 oxides to the pollutants. At near neutral pH, these oxides have very low solubility product constants [4,5]. This binding to insoluble oxides effectively makes most captured pollutants non-leachable and suitable for landfill. It has been noted that many pollutants captured in this manner also formed acid resistant compounds that passed TCLP toxicity leach tests [6]. 

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