Unipure Gives Red River a New Lease on Life

Unipure Europe Ltd (UK), specialists in water treatment and metal precipitation technology, are working in partnership with the Environment Agency Wales (EAW) to trial a high density sludge treatment plant at Parys Mountain Copper Mine, Anglesey, Wales.
Thousands of years of copper mining has led to high concentrations of metals leaching from the mines into the Afon Goch Amlwch, making it one of the most polluted rivers in Wales.
Both the elevated metal concentrations and the colour change upon oxidation means the river is now famous for its red flow, which looks dramatic against the rugged landscape, but which leaves behind contaminants which are extremely harmful to the surrounding environment.
In 2005, the EAW requested tests be undertaken to assess the environmental impact of the acid mine drainage and determine the most appropriate long-term treatment option. Unipure Europe Limited won the contract to treat the river water and determined that active treatment using lime dosing and high density sludge recirculation would be the best option for the initial eight week trial period.
Unipure Associate Director, Mr Patrick McKelvey, explained: “The water treatment process involves the addition of lime or caustic soda to increase the pH of the water and to promote the precipitation of metals in sludge.
“Other systems on the plant are designed to optimise the characteristics of the sludge to allow easier disposal. Approximately 99 percent of the metals in the minewater are precipitated and the water can then be discharged back into the environment.”
Speaking on behalf of the Environment Agency, Senior Environment Officer, Euryn Roberts, said: “After a successful tendering process we chose Unipure because they were the most cost effective and had a proven track record after installing a similar plant to treat mine water at the Wheal Jane tin mine, in Cornwall.
“After treatment the mine water is much, much cleaner which proves that the process technology really works, and we are extremely pleased with the results.
“Rivers and lakes in Wales have to meet a certain standard these days in line with European directives. A permanent plant of this type, at this site, would result in a healthier, cleaner river and a better place for local wildlife and people living nearby.”
The high density sludge treatment plant is a smaller version of larger scale works that Unipure has designed and constructed for metal mines in Cornwall and coal mine discharges in the North of England. It is an easily transportable unit which can be set up at most mine water discharges to test treatment technologies and to collect data for the design of a full scale plant.