Passive Treatment of Minewater at the Schlema-Alberoda Site

A pilot scale constructed wetland for treatment of seepage water from uranium mining was planned, built and operated. The pilot plant was designed for treatment of 5 m

3

per hour. The system consists of 4 basins and 1 lagoon. The objective of the project was the investigation of the long-term stability and robustness of passive water treatment systems. The feasibility of treatment of seepage water from uranium mining in constructed wetlands was proven by the operation of the pilot plant. A series of robustness investigations was conducted; including the operation during long lasting frost periods, under increased hydraulic load and under high carbon load. By using a tracer the hydraulic characteristics of the basins was tested. The control of the wetland is very complex due to different redox condition necessary for removal of arsenic (aerobic) and uranium (anaerobic). Additional information for an increased robustness of the system was derived from the operational results.