Prj 9712 - Underground water decontamination at a Copper Mine Site - Case Study
Starting May 1997, on authorization from BHP Copper (Tucson, Arizona) a BIOREM lab test was performed on underground water from BHP Miami-Globe mining operation (Arizona). Samples consisted of contaminated underground water and some alluvial soil taken in the vicinity of the well.
The soil made possible the set-up of two columns as in figure. From water and soil there were selected the indigenous sulfur reducing bacteria that were grown to critical mass for further injection into columns.
Column #1 was injected with biomass grown for 6 days while Column #2 was injected with biomass grown for 3 days that means that Column #1 was injected with biomass at higher concentration than Column #2. After a conditioning period (5 days), the polluted water was allowed to percolate upwards through the soil in the respective columns at different flow rates.
Chemical analysis of the contaminated water reported:
- pH = 4.6
- SO4-- = 2600 mg/l
- Cu = 150 mg/l
The dynamic of remediation is immediately perceivable from figures below showing that BIOREM is an effective method for the decontamination of underground water from the Miami-Globe mining site. It was specifically noticed that:
- BIOREM reduced SO4-- in the water from the initial 2600 mg/l down to 200 mg/l in 2 days (in the Column#1).
- Copper concentration in the water was reduced from the initial 150 mg/l down to non-detectable level within 6 days.
Moreover it was confirmed that the degree of decontamination is directly related to the biomass level and to the water flow rate trough the alluvial soil