The $1.5 million trial which aims to clean up NSW’s wastewater
The trial process halved the aluminum and copper levels in the wastewater and removed 80 percent iron, 70 percent manganese and 90 percent zinc. Most importantly, it reduced the bioavailable forms of nitrogen to near zero.
“These are really easily taken up by algae and plants in aquatic environments,” James said. “When you have too much of this bioavailable nutrient, weed growth begins.”
Workers harvest the resulting clumps of hair oedagonium and spin it into a “fluffy green cloud” that is composted or used as a rich fertilizer for a nearby native nursery.
Under the microscope oedagonium Filaments resemble green straws. This simple structure allows the macroalgae to grow rapidly (it grows 14 times faster than sugar cane) and, unlike species that float on the surface, oedagonium forms a pollutant-binding network through the entire water column.
Pacific Bio worked with James Cook University to develop an ‘algae atlas’ – a catalog of useful macroalgae, algae and seaweeds – which they consulted to select a species for the NSW trial.
“The macroalgae that do the heavy lifting in Picton are actually local to the Picton region, which is really important because we want to use a local species,” said Sam Bastounas, Pacific Bio’s managing director.
The macroalgae used in the experiment is a fast-growing freshwater weed species that grows locally.Credit: Nick Moir
Burdekin Shire Council in North Queensland is building Australia’s first macroalgae bioremediation facility in Ayr using Pacific Bio’s process called RegenAqua, which Professor Tim Flannery described as “breakthrough for the health of the Great Barrier Reef”.
Fish and shrimp farmers have also used the process to clean up aquaculture waste in Queensland.
The small Picton trial is the first of its kind in NSW. With continued success, the process could be scaled up to treat more water.
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The process slows in winter due to lower light levels and cooler temperatures, but James said the macroalgae still outperformed other technologies, such as expensive and energy-intensive membrane treatment.
“We use macroalgae to do the work of the traditional factory or membrane reactor,” Bastounas said.
“Sydney Water has shown that we can now do this in temperate climates, not just tropical ones, which is so exciting.”
