Toxicological Assessment of Hazardous Waste Samples Extracted with Deionized Water or Sodium Acetate (TCLP) Leaching Media

Abstract

Sodium acetate and deionized water elutriates prepared from municipal and industrial waste products, and the sodium acetate leaching media per se, recommended by the EPA for the Toxicity Characteristic Leaching Procedure (TCLP), were bioassayed for their toxicity potential. The toxicity bioassay organisms included: algae, Selenastrum capricornutum; macroinvertebrates, Daphnia magna; lettuce seed root elongation, Lactuca sativa L.; and, bacteria (Microtox), Photobacterium phosphoreum. The pH 5.0 sodium acetate leaching media was highly toxic to each of the test organisms. Adjustment of the pH to 7.0 decreased toxicity approximately 2.5-fold for algae and lettuce, and 6-fold for D. magna. This reduction, while statistically significant, did not change the toxicity classification of the sodium acetate leaching media. Photobacterium phosphoreum was un-affected by pH 7 sodium acetate leaching media after 30-minutes exposure. Toxicity of the industrial waste TCLP elutriates to D. magna and S. capricornutum was similar to that obtained in the elutriates prepared with deionized water. The response of D. magna to the TCLP elutriates from sewage sludge (POTW #2), municipal ash #1 and #2, paint sludge #2, Midco volatile soil, and First Chemical Corp. indicated that these samples contained acetate soluble contaminants which were more toxic than the sodium acetate itself. Bioassays detected toxicity in either TCLP or deionized water eluted samples. Toxicity of water eluted samples can be attributed to materials leached from the waste. Toxicity of the TCLP eluted samples is problematic due to uncertainty of the amount of toxicity attributable to the leaching media itself vs. the materials leached from the wastes.