Is a mining operations sewage evaporation pond able to biologically remediate acid pit dewatering water?
Workshop Evaporation Pond 2 (WEP2) is a water body used to reduce low pH and/or high salinity surface water volumes through evaporation. Approximately 4 ML of acid dewatering water from WEP2 was introduced into the 60 ML Workshop Evaporation Pond 1 (WEP1) in late May 2003. WEP1 is a hyper-eutrophic water body into which raw sewage and CCP workshop vehicle washdown and waste waters are continuously fed. In situ sulfate reduction processes produced alkalinity and removed heavy metals from WEP2 waters. It appears that the WEP1 wetland has fulfilled an example of a site-specific, medium-scale evaluation of the proposed in-void remediation technology. This conclusion is further borne out by the large number of macroinvertebrates and high phytoplankton abundances present again, and by the many species of waterfowl also now making use of this previously inhospitable water body.
Photos: Workshop Evaporation Ponds 2 (WEP2) and 1 (WEP1)
Figure: Changes in WEP1 pH and EC over time
McCullough, C. D.; Lund, M. A. & May, J. M. (2008). Field scale demonstration of the potential for sewage to remediate acidic mine waters. Mine Water and the Environment. 27(1): 31-39. link