ABSTRACT
Oversaturated calcium carbonate levels and unutilized carbonaceous material prevent water from being reused directly after anaerobic treatment. A promising new process entails the biological reduction of sulphate to sulphide by the bacterium Desulfovibrio desulfuricans. Sulphide can, in turn, be converted to elemental sulphur. Mining effluents are major contributors to mineralization of receiving waters and may prove toxic to men, animals, and plants due to unacceptably high concentrations of heavy metals and cyanide. If it is mainly heavy metals that need to be removed from mining effluents, the process can serve as a sulphide source by treating a side stream for sulphate reduction. In the continuous flow reactor samples were taken daily from the distribution chamber and analyzed for sulphate, sulphide, alkalinity, chemical oxygen demand, and pH. Aerobic treatment likewise was conducted in batch systems, after supplementing process water with ammonia-N and phosphate-P to concentration levels of 20 and 4 mg/L respectively.
