[en] Column studies utilizing coarse, oxidized uranium tailings and fine particle size mixed sulfide base metal tailings were conducted to determine whether or not an oxygen-scavenging, biofilm could be established in mine tailings to reduce or prevent the ingress of dissolved or atmospheric oxygen. The results to date have been encouraging. A microbial biofilm layer develops within three to six weeks and the Eh and the dissolved oxygen content of the column effluents decreases rapidly with a concurrent increase in the pH of the column effluents