Ecotoxicology of Highly Treated Mine Waters: Lessons from an Australian Mine

Mining operations commonly treat mine water prior to discharging it to the environment. Results of biological toxicity tests and Toxicity Identification Evaluations have shown that environmental risks can still exist for these highly treated waters. We present examples for mine waters that were treated using high density sludge–microfiltration–reverse osmosis and brine concentration
processes. While such treatment substantially reduces the primary toxicity of the water, three key factors that could affect environmental consequences may
arise or persist: (1) residual contaminants may still be at toxic concentrations, (2) the bioavailability of residual contaminants may increase, and (3) the treated water may be nutrient or major ion deficient. Appropriate strategies for the management of these treated waters should consider that toxicity or other water quality risks may still exist and that these will differ from those of the untreated water.