Use of conductivity to monitor the treatment of acid mine drainage by sulphate-reducing bacteria

Measurements of electrical conductivity were obtained during treatment of acid mine drainage (AMD) by sulphate-reducing bacteria (SRB) in fed-batch column reactors. The advantages of this method are that it is non-invasive, non-destructive, and rapid, giving real-time information. Conductivity measurements were taken on an hourly basis throughout the course of several experiments in which the SRB were exposed to different quantities of fresh AMD. Simultaneous measurements were taken in a column in which no SRB were present but were also exposed to the same volumes of fresh AMD. As treatment of the AMD progressed, increases in conductivity were measured, generally localized to two regions in the gravel bed: the top and bottom 10 cm (4″). Changes in conductivity were not always coincident with changes in ORP and pH, indicating that conductivity may be a more sensitive tool for locating and monitoring specific zones of SRB activity.