Mussel shells to treat polluted mining water

University of Canterbury (UC) researchers are investigating an ecologically engineered treatment system to solve wastewater problems, such as acid mine drainage, on mining sites.

Acid mine drainage is a significant water pollution problem for mining industries, with thousands of kilometres of streams and rivers severely affected each year around the world. In New Zealand, key mining areas are located on the West Coast of the South Island, Coromandel Peninsula and Southland.

UC natural resources engineering PhD student Benjamin Uster, working under the supervision of Dr Aisling O’Sullivan, is studying an environmentally friendly treatment system to remove acidity and metals from the mining-affected waters.

“Polluted mining water impacts aquatic systems downstream from a mining site. Streams affected by acid mine drainage typically support little, if any, living organisms and are unsuitable for recreational water activities,” Uster said.

“I am conducting several lab-scale experiments using waste mussel shells that neutralise the acidity and remove the metals from the mining wastewater. I am also using other waste products, including compost and wood bark mulch, that feed the bacteria responsible for the treatment. No synthetic products or any chemical reagents are used in this treatment system so it is a relatively sustainable strategy.”

The research builds on previous work within the research group that was the first worldwide to use waste mussel shells instead of more common quarried limestone to treat acid mine drainage. Uster’s work is showing how fast the treatment can be achieved and how much more efficient mussel shells are than limestone at treating the mining wastewater.

“I hope to confirm by the end of the year that the use of mussel shells in treatment systems similar to engineered wetlands are an efficient and sustainable way for treating acidic waters in New Zealand,” Uster said.

Uster will present a paper on his study at the Australasian Institute of Mining and Metallurgy conference in Nelson in August. Funding for the UC research has been provided by CRL Energy and by the University of Lausanne, Switzerland.