Development of an innovative treatment system for acidity problems in an urban lake (Spoonbill Lakes) resulting from acid sulphate soils
Urban development in the City of Stirling, Western Australia, has led to exposure of acid sulfate soils (ASS) causing acidification of groundwater and metal/metalloid (including arsenic) toxicity. This acidic and toxic groundwater flows through the Spoonbill Lakes causing environmental and health impacts on this wildlife reserve. This treatment of groundwater in an urban context poses a new and challenging problem for environmental managers. To treat this problem, an innovative modular treatment system, has been constructed and is being experimentally tested at the Lakes. The project will produce a design for a permanent treatment system at the Lake, and similar situations.
Injection with either sodium hydroxide, calcium hydroxide or oxic lime chip liming remediates pH and reduces iron and aluminium concentrations. These metal precipitates are then removed in a settling tank. Organic bioreactorsthen reduce sulphate and precipitates heavy metals and arsenic. The north lake functions as an untreated, reference site. The northern half of the south lake has been enhanced with extra plantings and wood mulching to develop a final aerobic wetland polishing treatment for the neutral pH and low solute water product. Finally, treated water is left to travel through the remaining aerobic un-rehabilitated lake and percolate back into the groundwater system.
Dr Clint McCullough
Associate Professor Mark Lund
Curtin University of Technology, Mr Avijit Das
Curtin University of Technology, Dr Ron Watkins