Over the past three years, Noranda Technology Centre (NTC) has evaluated the feasibility of using sulphate-reducing bacteria (SRB) to treat acid mine drainage (AMO), in a pit or an underground mine. Following an initial study conducted in batch flasks that determined major process parameters (residence time, temperature effect, nutrients and substrate requirements), a conceptual flow sheet was developed. In order to confirm the concept for full-scale application, the present study included screening and· selection of inexpensive nutrients and larger scale tests in a 280-L drum, a 160-L tall column and 5-L continuous reactors. The start-up conditions examined with drum tests included sediment formation (reactor inoculation methods and nutrient preconditioning), influent location and final effluent quality (e.g. metals, pH, BOD, COD, odor, etc.). The tall-column test (5 m) was conducted to define the reaction zone and the extension of H 2 S dispersion in the pit. Nutrient utilization and S balance were estimated by monitoring off gases in 5-L continuous reactors as well as effluent quality. Due to the low S0 4 conversion rate found at low temperatures (e.g. 4 to 10°C), which is found in the bottom of the pit, the amount of nutrients required to treat moderate strength AMO with a high flow rate was determined to be very high, causing technical and economical difficulties in full-scale application of the process. The process was recommended for low loading situations.