Biological Methods to Remove Selected Inorganic Pollutants from Uranium Mine Wastewater

Abstract

In many mining operations the mines are de-watered, i.e. water is pumped from the mines to prevent flooding of operations. The water often contains low concentrations of the elements being mined as well as other associated ions. These waters must be treated to meet governmental regulatory standards before being discharged. Some of the mine waters are used in milling processes, and become even more laden with soluble inorganic ions. These brines are pumped to tailings ponds for evaporation or eventual release to surface or ground water systems. Both mine waters and tailings solutions are valuable sources of metal and other ions, and it is both economically and environmentally sound to recover these elements. In the state of New Mexico, U.S.A., industries which must remove inorganic agents from large volumes of water are the uranium and molybdenum operations. Although precipitation, ion exchange, solvent extraction and electrowinning systems are available for soluble ion removal, these systems are quite often ion specific and very expensive when treating large volumes of water. An inexpensive and ion non-specific, accumulator system is the desirable alternative. The understanding and design of a functional bio-filter system for removal of uranium and other ions associated with uranium mining operations would alleviate discharge problems in the Grants, New Mexico, U.S.A. district (the producer of 46% of the U.S. uranium). Such a system would be applicable to other uranium-producing regions. The bio-filter process may also be applicable to other industries, with wastewater effluents containing trace elements. Among the extractive industries, the molybdenum operations have considerable need for economic and environmentally safe processes for purification of mill effluents.