Microalgae could be used to clean up nuclear effluent

Effluent and wastewater produced by nuclear facilities can be difficult to clean up. However, a type of algae that is tolerant to radiation could soon be used to clean up these products.

The microalga Coccomyxa actinabiotis was discovered in a used fuel cell storage pool at a nuclear facility and is capable of withstanding extreme radiation doses of up to 20 kilograys (kGy).

By comparison, humans exposed to a fraction of this level of radiation - five or more gray (Gy) - usually results in death within 14 days. In 1986, the Chernobyl nuclear accident resulted in human exposure up to 16 gy causing 28 deaths in the first three months.

Microorganisms, including algae, are used widely by industry to help manage waste by-products. The discovery of the new alga creates the potential to develop cheaper and more environmentally friendly solutions for cleaning up effluents and water used by nuclear facilities.

The potential of the alga, which uses photosynthesis and metabolic processes to take-up the contaminants, is being explored by a French research team from Grenoble University, Montpellier University, Institut Laue-Langevin, and the Atomic Energy and Alternative Energies Commission - Division of Nuclear Energy.

The research team is currently developing a pilot-scale treatment unit, based on the Coccomyxa actinabiotis microalga, to remove effluents including carbon-14, uranium-238 and caesium-137.

“Current technologies for the chemically engineered cleaning of nuclear effluents are robust and efficient. However, processes like evaporation, filtration, sorption and ion exchange can be expensive,” said the Institution of Chemical Engineers’ (IChemE) chief executive, Dr David Brown.

“Work in other industries indicates that decontamination using bioremediation technologies could be equally as efficient, but cheaper and more environmentally friendly. But none is currently operational in highly radioactive environments.

“The researchers in France are breaking new ground by helping us to understand the feasibility of using algae for the highly controlled nuclear decontamination process, including issues such as fouling, pore size and re-use of this remarkable alga.”

The role of chemical engineers in the health, water, food and energy sectors is explored in IChemE’s latest technical strategy, Chemical Engineering Matters