By-products can help treat metal-contaminated water
Photo: Viktor Sjöberg
By-products from the metal and wood processing industry may find a new application in the treatment of polluted water. A research project funded by the Swedish Geotechnical Institute (SGI) demonstrates that materials such as bark and slag can sorb several environmentally hazardous metals and thereby reduce their dispersion from contaminated sites.
In a multi-year research project, Örebro University investigated how bark and different types of slag can be used to sorb chromium (VI), nickel, zinc, arsenic, cadmium, lead and uranium, preventing these contaminants from being transported in polluted water to the surrounding environment. The project was funded through SGI’s research and technology development programme on contamined sites TUFFO, together with co-financing from collaborating project partners.
The project included laboratory-scale batch and column tests in which the sorption capacity of the by-products and their long-term stability were evaluated. The results show that water-cooled slag has a significantly higher sorption capacity than air-cooled slag, particularly for nickel, zinc, cadmium and lead. Certain bark types, on the other hand, demonstrated a strong ability to sorb chromium (VI).
Mesoscale trials were also carried out to investigate the effectiveness of slag in sorbing zinc under higher water-flow conditions.
The findings provide a basis for future full-scale trials and indicate that by-products have the potential to be used in environmentally and cost-effective solutions for the treatment of polluted water.