Treatment of Acid and Metalliferous Drainage at a Derelict Mine Site

Earth Systems was engaged to provide water treatment services at a derelict mine site in NSW to prevent the uncontrolled discharge of acid and metalliferous water into the surrounding environment. Optimum target pH and reagent types including alkali and flocculant were determined based on an in-house water quality treatment tool.

A dosing strategy was implemented to permit rapid equilibration at surface and depth. Uniform metal removal via precipitation and adsorption was completed. Within a few days 99% metal removal was achieved enabling safe discharge to the local river.

The discharged water quality complied with ANZECC water quality guidelines for the protection of better than 95 % of species for all identified metals of concern and was generally better than the background downstream water quality.

Water quality of the dam before and after treatment for all identified metals of concern in comparison with ANZECC (2000) water quality guidelines. Concentrations indicated are in mg/L.

Analyte Dam water quality
– Before treatment
Dam water quality
– After treatment
ANZECC (2000) 95% guideline value *
Arsenic <0.02 <0.001 0.013
Cadmium 0.486 <0.0001 0.0002
Copper 2.08 0.001 0.0014
Lead 4.33 <0.001 0.0034
Nickel 0.04 <0.001 0.011
Zinc 108 <0.005 0.008

* ANZECC and ARMCANZ (2000).  Australian and New Zealand Guidelines for Fresh and Marine Water Quality.  Australian and New Zealand Environment and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

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