Contaminated water treatment in cold regions: an example of coagulation and dewatering modelling in Antarctica

Water collection and treatment is often required for effective cold regions contaminated site clean-up, where large volumes of meltwater runoff might otherwise become contaminated during remediation activities and disperse pollutants into the surrounding environment. Waste reduction is particularly important for remediation activities in remote cold regions, as the handling, transport and eventual disposal of material is very costly and logistically difficult. A mobile water treatment system has been constructed for deployment to remote cold regions contaminated sites for use during clean-up activities. This paper describes coagulation and dewatering experiments and modelling techniques that were used to optimise the water treatment process and reduce sludge volumes. Coagulation was assessed by laboratory experiments to determine the impact of a number of operating parameters. Sludge dewaterability was characterised using a recent theory of suspension consolidation. The parameters of greatest importance for water treatment were pH, flowrate and the ratio of coagulant to suspended solids. Sludge dewatering experiments and modelling found transient batch settling and freeze–thaw to be the most effective sludge reduction techniques for Antarctic applications.