Harvesting biomass from wastewater recycling

Environmental health experts at Flinders University are advancing research into a highly sustainable wastewater recycling program by developing a cost-effective way to harvest microalgal biomass for use in biofuels and other applications.

The high-rate algal pond (HRAP) model, recycling wastewater at two regional South Australian locations at Kingston-on-Murray and Peterborough, uses algae and bacteria to treat the wastewater.

Research led by Flinders University Professor Howard Fallowfield and Dr Paul Young has presented details of a new system using slaked lime and magnesium concentration to concentrate the microalgae-rich biosolids produced in the HRAP at Kingston-on-Murray. Chemical reaction modelling was used to optimise the processing and the cost of chemicals was evaluated, with the results published in the journal Algal Research.

“This autoflocculation process was successful in harvesting the biosolids while significantly reducing the turbidity, nutrients and E. coli contamination left in the wastewater,” said Dr Young, who completed a PhD at Flinders University.

Professor Howard Fallowfield testing the HRAP system.

Prof Fallowfield says the study shows for the first time that the HRAP wastewater treatment system could also be used to efficiently harvest microalgae grown in a low-cost environment — without the need for further investment in expensive infrastructure.

“The integration of treatment and biosolid recovery offers new configurations for the operation of HRAP-based wastewater treatment systems,” he said.

Top image: The Peterborough HRAP under construction.