Recent advances in technologies for biological treatment of thiocyanate, cyanide, heavy metals and nitrates

Biological treatment of mining and industrial effluents reached full scale commercialization around 1980. These proven, low cost, technologies have been limited in application due to a number of factors, including extended periods of time and cost required for pilot testing as compared to chemical treatment technologies, lack of biological expel-rise in metallurgical personnel, longer treatment periods in some cases, and performance failures based on improper application. Renewed interest in biological treatment technologies is being driven by permits with lower effluent concentration criteria, permits with bioassay evaluation, the need to remove thiocyanate, nitrates, sulfates and other parameters. Chemical treatment processes, in general, have not been able to meet these present requirements, or require elaborate combinations of processes, in terms of effluent duality and treatment economics. This paper addresses biological treatment of mining and industrial waste waters and selected recent advances in these technologies. The future looks very bright for application of these low capital and operating cost technologies.