Xanthates, key compounds used in the mining industry for the separation of metals from ores, may have a significant impact on the ecosystems once discarded into the tailings. The aims of this study were to : characterize chemical and microbiological conditions in a tailings lagoon (Brown Creek gold mine); examine the feasability of using indigenous bacteria to degrade xanthate under laboratory conditions; and, optimize the biodegradation process by employing biofilm technology and plant-microbe associations. To achieve these, a simple but accurate HPLC method was developed. The chemical and biological constitution of the tailings lagoon was monitored over a 2 year period from March 1995 to February 1997. Xanthate degradative performance was improved by Phragmites australis and its root associated bacterial community. Cumulative amounts of xanthate degraded by this plant-microbe association were significantly higher than any other treatment, specifically glass-attached and free-living bacterial populations. An increased bacterial number in the extensively developed root, the presence of extracellular layer as revealed from scanning electron microscope and significance of plant removal via uptake were thought to be the possible explanations for the enhanced biodegradation activity observed. In view of the above, use of glass-attached bacteria and plant-microbe associations might provide a feasible solution to degrade xanthate in the tailings lagoon. The results obtained from this study suggest that the plant-microbe associations could provide a cost effective method to degrade/remove xanthate from the tailings lagoon runoff. This approach offers several ecological advantages. Firstly, it offers the advantage of a solar-powered treatment system that is aesthetically pleasing. Secondly, bioremediation can be done on site, thereby eliminating waste transportation costs. Finally, it has the added attraction of a higher potential for public acceptance / Doctor of Philosophy (PhD)