Water filtration with mineral-based byproducts as a sustainable treatment technology

Important results from the project

The aim of the project was to investigate whether the 200 kton slag that is not used optimally or deposited every year can be used permanently in new applications ensuring future outlets and providing added value for the steel industry and society. Five goals existed and could be met; test of filter material for purification in small sewage plants, testing of mineral filters for industrial wastewater and stormwater, new technology to build road shoulders on busy roads with slag that simultaneously cleans stormwater, laboratory-tested filter products, and two graduated doctors

Expected long term effects

Slag´s properties can be modified in the furnace to contain minerals that have properties to bind phosphorus or metals from water. Slags can separate both cations and anions from contaminated water, anions even at pH value 10. Furthermore, slag and bark can separate PFAS and fluorine is removed by a modification of AOD slag. Some types of slag are recommended to replace sand in soil beds for sewage treatment. Stormwater wells in cities and industry can be equipped with slag filters. Storm water from traffic-intensive roads can be cleaned in the road shoulder with certain types of slag.

Approach and implementation

R&D has been conducted in clear collaboration between industry and academia. The research has been conducted in the laboratory, at the companies and in the field. Implementation has been possible through researchers and companies starting pilot facilities and studying their function and utility to achieve sustainability goals. The analysis made is that different types of Swedish-produced slag are by-products that can be used after simple reprocessing or after modifications in water purification applications. These applications can vary and be interesting for several end users.