Three by-products from the steel and paper manufacturing industries have been tested as filter materials for removal of heavy metals in metal solution and in landfill leachate. Laboratory experiments were used to determine the capacity of the materials to remove heavy metals. A column set-up at a landfill site examined the field application possibilities of pine bark, amorphous and crystalline blast furnace slag. All three materials have shown large potential for removal of heavy metals inmetal solution also when the concentrations are low. On-site treatment however was distrurbed by factors not present in batch experiments. Physical parameters such as pH and electric conductivity of the water stream were not significantly affected by the treatment.