Efficacy of Clearflow Treatment Technologies in the Treatment of Mining Effluent: Field‐Level Testing at a Coal Mine

Mining waste water characteristically contains high concentrations of suspended solids, total metals, and nutrients. These can be treated with flocculants within settling ponds to speed up the clarification of water by settling out the suspended solids. Cationic flocculants can be very effective in water treatment but are also highly toxic to aquatic life, causing fish death by impairing gill function, therefore they are generally not used where discharge of treated water to fish bearing environments is required. Recently, it was demonstrated that toxicity of cationic flocculants can be effectively ameliorated by neutralizing products developed by the Clearflow Group. The current study uses a full‐scale field‐based approach to examine the effects of combined cationic flocculant and neutralizer treatment on nutrient and metal contaminant removal from effluent. These assessments were coupled with fish toxicity testing and invertebrate community analysis in the receiving environment. Results show that the full treatment sequence substantially reduced concentrations of many mine‐water pollutants. Importantly, there was no acute toxicity to trout fingerlings from mine‐water treated with both cationic flocculant and neutralizing agent. Invertebrate community structure was notably different at the effluent discharge site compared to the receiving river system. However, areas 50 and 100 m downstream had largely similar invertebrate diversity compared with upstream control sites.