Document Type


Date of Award


Degree Name

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


Chemical Engineering, Chemistry and Environmental Science

First Advisor

Piero M. Armenante

Second Advisor

David Kafkewitz

Third Advisor

Henry Shaw


Heavy metals are contaminants of both solid and liquid wastes. For example, the ash produced from the incineration of domestic or industrial wastes often contains substantial concentration of lead, mercury, cadmium and other heavy metals that make it a hazardous waste. These heavy metals in wastes are hazardous because they are mobile. Immobilization of the metals is an effective method of rendering the metals harmless, provided that immobilization is irreversible. This study focused on the heavy metal immobilization potential associated with the activities of anaerobic bacteria known as the dissimilatory sulfate reducers (Postgate, 1984). The sulfate-reducing bacteria produce sulfide and form highly insoluble precipitates of the metals. Cupric sulfide, cadmium sulfide, mercuric sulfide and lead sulfide are examples of these insoluble salts. Our research will have an additional advantage because it means that the biological process of immobilization of the heavy metals can be made to continue underground for many years after the treated ash has been buried thus providing extra protecting against remobilization of the metals.



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