Algae: An unlikely solution for post-mining transitions 
A new CSIRO-led project suggests algae could unlock sustainable futures for mine sites, surrounding ecosystems and local communities.
With support from the Cooperative Research Centre for Transformations in Mining Economies (CRC TiME), the CSIRO-led research team in collaboration with The University of Queensland and Murdoch University, has found notable benefits in using algae-based technologies to help mitigate the environmental impacts of mining during operations and after closure.
With 240 mines in Australia projected to close by 2040, algae could be key in managing site water quality, improving mine closure outcomes and creating business opportunities.
Global algae markets were valued at about $2.9b – $8b (US$1.9b – 5.3b) in 2023, with a rapidly increasing annual growth of about 5 – 6%.
The project brought together expertise from multiple industry and government partners, including South32 (ASX: S32), Fortescue (ASX: FMG), Rio Tinto (ASX: RIO), Heidelberg Materials, Energy Australia, the Queensland Mine Rehabilitation Commissioner and the WA Minerals Research Institute (MRIWA), to assess whether algae could help reduce the environmental footprint of mining, while also creating pathways for regional economic development.
Integrating algae into mine site closure planning could enable the creation of algae-based supply chains — with potential for regional, Indigenous and Australian enterprises.
The application of algae at mine sites could accelerates ecological recovery while reducing environmental impacts, such as pollutant levels and greenhouse gas emissions, according to CRC TiME.
Additionally, algae-based technologies could create sustainable business opportunities, turning post-mining land into economically productive ecosystems, according to the report.
This opens up opportunity to ensure long-term sustainability for mining sites and value generation beyond mine closure. Algal cultivation at mine sites could also create jobs and offer opportunities to engage Traditional Owners and other local communities, according to CRC TiME.
The research shows that various micro- and macro-algae have been detected and identified in mine waters, indicating that, with suitable growth conditions and the selection of appropriate species, algae have the potential to be commercially cultivated at mine sites.
Cultivating algae in mine water can remove pollutants and sequester carbon dioxide. Algal biomass could also be used to suppress dust and improve plant growth as a fertiliser and biostimulant.
The report noted several benefits from algal technologies at mine sites, including:
- The combination of ecological restoration with economic value generation for mutually beneficial outcomes.
- The application of algae at mine sites accelerates ecological recovery while reducing environmental impacts from pollutants and greenhouse gas emissions.
- Algal biomass can be used as a raw material to produce bioplastics, biofuels, pigments and animal feeds.
- Business opportunities can emerge from algae-based technologies, transforming post-mining land into economic productive ecosystems.
- Cultivating algae at mine sites could create ongoing value to regions after closure, with potential to support future jobs and opportunities for Traditional Owners, local businesses and communities.
CSIRO senior principal research scientist, project leader and one of the authors of the report, Dr Anna Kaksonen comments on the results.
“Algal technologies offer exciting opportunities for mine sites for mine water treatment, mine waste stabilisation, dust suppression and creating topsoil for improving plant growth during rehabilitation,” she said.
“Algae can be cultivated on non-arable land, making them suitable for remote mine sites where agricultural activities may not be viable.
“They grow relatively quickly, fix carbon dioxide through photosynthesis and produce organic biomass that can be used directly on site or processed into valuable products. This offers environmental benefits while also reducing the need to transport materials from elsewhere — often a significant cost for mining operations in remote areas.
“Many Australian mine sites have poor water quality, often with high levels of sulfate or metals.
“If algae can help improve the water quality, it can be an important tool for water treatment.”
Algal biomass may also assist with revegetation and mine site rehabilitation by acting as a bio-stimulant, increasing soil organic carbon content and supporting the establishment of plants in areas where topsoil is limited or depleted, according to CSIRO.
“In Australia, topsoil is often stripped away when mines are established and stockpiled for rehabilitation, but the quality of the topsoil degrades during storage,” Dr Kaksonen said.
“Using algae as a soil amendment would help support plant establishment and site rehabilitation when operations have finished.”
CRC TiME chief executive Dr Guy Boggs says water treatment and management of acid mine drainage remains a significant hurdle to successful transitioning to next land uses.
“If industry can capitalise on new technologies like algae and algal biomass to improve water conditions, this could help both risk reduction and value creation — key factors in transforming regions after mining,” he said.
The cultivation and use of algae at mine sites will require consideration of a range of factors, including land use agreements, environmental permits and compliance, health and safety standards and biodiversity and ecosystem protection.
The report suggests a next step will be assembling a to support industry to identify barriers and opportunities. The database would consist of government, industry and societal requirements that impact algae biomass production.
Other steps including laboratory-scale evaluations of mine site waters and engagement with First Nations and regional communities to identify the most promising algal technologies for scale-up and further demonstration.
A business case for the establishment of algae production within the context of Australian mine sites would consist of several economic, environmental, community and indigenous aspects and successful commercialisation of algae-based products requires a comprehensive path to market.