Environment Algae turns heavy metals green

Algae turns heavy metals green

Algae can remove heavy metals from industrial wastewater and can grow biofuels at the same time, James Cook University researchers have found.

JCU chemical engineering academic Dr Madoc Sheehan, Associate Professor Kirsten Heimann, and past JCU chemical engineering students Hannah Palma and Emily Killoran have successfully grown microalgae biofilms in tailings dam water at Queensland Nickel.

Dr Sheehan, who is a chemical engineering sustainability expert, said the scientists used algae to turn a problem into a solution.

“Microalgae biofilms grow on the surface of wet rocks and on the sides of boats and marine structures. It’s better known as biofouling and it’s an expensive and time-consuming problem for boat owners and marine operators.

“It grows by using energy from the sun while simultaneously consuming CO2, nutrients and dissolved metals, and it can absorb other metals that are dissolved in water.”

The Queensland Nickel site contained dissolved metals such as cobalt, nickel and manganese, yet the team found they could grow algae at rates similar to commercial algae operations and clean the water at the same time.

Associate Professor Heimann is an industrial algal biotechnologist and ecotoxicologist. She said the water can be more easily re-used by industry once it’s cleaned, and poses less of a danger to ecosystems such as the Great Barrier Reef.

“Algae grown in the tailings water reduced the nitrogen content and the heavy metal content of the water, lowering its pollution potential. It absorbed the dissolved metals as it grew, to the extent that when harvested at least 10% of the algae’s dry weight was made up of pollutants,” she said.

Dr Sheehan said algae grown in Queensland Nickel tailings water was 40% carbohydrate, making it suitable for converting into a biofuel such as ethanol.

“This means the energy obtained by turning the algae into biofuel could potentially be re-used to harvest and grow the algae in the first place, making the process cheap and effective.”

Associate Professor Heimann said “We can see the day that mine waste waters become a valuable future resource, rather than the economic cost and environmental burden that they currently are.”

Read more about this intriguing study here. Story credit: James Cook University newsroom.

Research to make industry more sustainable is only possible if we support our universities. To keep Australia clever, please sign the petition below.