Researchers in Australia are advancing research into a sustainable wastewater recycling program by developing a cost-effective way to harvest microalgal biomass for use in biofuels and other applications. Two high-rate algal pond (HRAP) systems have been constructed to demonstrate the utility of algae and bacteria in treating wastewater for reuse.

Slaked lime is applied to raise the water pH and magnesium hydroxide is used to induce autoflocculation and concentrate the microalgae-rich biosolids produced in the HRAP. The treatment system efficiently harvested biosolids and significantly reduced turbidity, nutrient concentrations and Escherichia coli contamination in the wastewater.

The sustainable, low-energy systems are cost effective to operate, and incur a 40% lower capital cost of construction relative to the previous system for effluent-only schemes. A conventional system requires 66 days to treat the wastewater while HRAPs can perform a similar level of treatment in 5 to 10 days. The ability of the system described in Algal Research to remove pathogens is equal to, or better than, existing wastewater systems.

Scientists from Flinders University (Australia), the National Centre for Groundwater Research and Training (Australia) and Hasselt University (Belgium) contributed to this research.

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