Document Type

Thesis

Date of Award

1-31-1992

Degree Name

Master of Science in Environmental Science - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Piero M. Armenante

Second Advisor

David Kafkewitz

Third Advisor

Samir S. Sofer

Abstract

The heavy metals contained in incinerator ash constitute an environmental hazard because they can be leached out of the ash matrix by rain water after the ash is landfilled. This study focused on a novel biological treatment process in which immobilization of the heavy metal content of incinerator ash is achieved using naturally occurring microorganisms. Specifically, immobilization was obtained by the use of a sulfide producing bacteriological system. The genus Desulfovibrio was cultured under anaerobic conditions, providing a source of sulfide from the reduction of sulfate as a natural metabolic function. The sulfide produced then formed highly insoluble precipitates with the metals present after incinerator ash was introduced into the system. Untreated ash was tested for lead, cadmium and chromium content using a new leaching test known as the "pH 5 method". The ash failed EPA limits for both lead and cadmium. Following treatment, the ash passed the EPA leaching test (TCLP) and the more stringent pH 5 method for all three metals, suggesting that this treatment has potential as an ash treatment option prior to disposal.

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