Bioprocess for reducing sulphate and nitrate in mine waste water

Forrum Recycling and Waste Solutions AB were nominated as one of three finalists for the Swedish Mining Innovation Award in 2019, for a microbiological-based wastewater treatment process for lowering the sulphate and nitrate content of mine waste water. The concept is being tested at pilot scale at LKAB Svappavaara and consists of a prefiltration stage and a free floating biobed reactor.

structures for microbes to attach to in wastewater treatment
Plastic pieces give a surface for the microbes to attach to, to prevent them being washed out with the water.

Most mines face challenges meeting discharge limits on the allowable amount of sulphates and nitrates in the mine waste water. A summary of the wastewater treatment solution developed by Fortum is presented in a Youtube video. Mine waste water treatment is a focus of work package WP5 in the SEESIMA project.

Experimental work on sulphate reduction underway

Breakdown of sulphur-containing minerals often results in the release of sulphate (such as with acid mine drainage). One way to combat the environmental problems that this causes is to use certain types of bacteria that reduce the sulphate back to sulphur or sulphide compounds.

Sulphate reduction and metal sulphide removal experiments are going on at the University of Oulu. Sulphate reducing bacteria are cultivated in bottle scale and tested for utilization of KemiCond treated sewage sludge and succinate. At the same time synthetic mining water is treated, and iron is recovered as FeS. Furthermore, tests with other low-cost carbon sources and real mining waters, as well as reactor experiments are planned to be started in the autumn 2019.

sulphate reduction experiment over 2 weeks
Sulfate-reducing bacterial consortium cultivated in synthetic mining water at 6 °C with succinate as a carbon source.
continuous flow reactor for sulphate reduction experiments
Continuous up-flow reactor built up for biological sulfate reduction experiments

For more details, contact Hanna Virpiranta

Visit to Bangor University, Wales, UK

In February 2019 Dr. Tiina Leiviskä and MSc. Hanna Virpiranta visited Prof. David Barrie Johnson’s group Bangor Acidophile Research Team (BART) in Bangor University, Wales, UK. Hanna stayed there for two weeks working alongside with other visiting and post-doctoral researchers of the team. She acquired a lot of knowledge of e.g. operating sulfate-reducing bioreactors, plating of anaerobic microbes, and conducting bioleaching experiments, that she can exploit in her further research.