British Columbia Mine Reclamation Symposium

A performance comparison of arsenic, cadmium and zinc treatment in a duplicate column study of an anaerobic bioreactor operated at 4 degrees C and 25 degrees C Kawaja, Jonathan D. E.; Gould, W. Douglas; Morin, Lucie; Mattes, Al; Duncan, William F. A. (William Frederick Alexander)

Abstract

This study provides a performance comparison of arsenic, cadmium and zinc treatment at mildly acid to neutral pH in an anaerobic bioreactor (ABR) column experiment operated at 4°C and 25°C. The materials and contaminants were based on a field scale system operated by Nature Works Remediation Corp. for Teck Cominco Metals Ltd. in Trail, BC. The majority of arsenic was removed within the oxic zones of the ABR columns. Although it was thought that arsenic removal at this stage was attributed to sorption to iron, it is now known to be zinc arsenate. The work showed cadmium and zinc removal improved in relation to the extent of anoxic conditions in the columns. In the most anaerobic zone of the columns (i.e., characterized by good sulphate reducing bacteria (SRB) activity) effective zinc removal required a stable SRB population, but was not necessarily temperature dependent. However, there was a direct and significant impact to microbial activity as a result of a temperature change. The work suggested that internal monitoring of DO and SRB can provide valuable information with respect to significant metal removal mechanisms, and the active volume in which metal sulphides can be significantly generated. The information can be used to: troubleshoot an under-performing system, and make appropriate amendments to improve system performance.

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Attribution-NonCommercial-NoDerivatives 4.0 International