Cadmium Removal
As environmental regulations in the pulp and paper industry become increasingly stringent, the need for effective solutions to manage and reduce heavy metal emissions is growing. Cadmium, in particular—a metal found in small but environmentally hazardous concentrations in process water—has become a focal point for both research and industry. Noram International AB, based in Västra Frölunda and part of the Canadian NORAM Group, is driving progress through innovative filtration technologies.
The Challenge of Heavy Metals in Pulp Mills
Heavy metals such as cadmium, lead, and zinc tend to accumulate within the recycling cycle of pulp mills. Although concentrations are often low, these metals can build up in sludge and residual products, complicating reuse and increasing environmental impact. Achieving circular and sustainable production therefore requires technologies that enable efficient separation.
Pulsfilter – The Core of Noram’s Solution
Noram’s Pulsfilter technology, developed in collaboration with W.L. Gore & Associates GmbH, is based on advanced surface filtration using GORE® Filter Tube Assemblies. Unlike conventional multi-step filtration systems involving clarifiers, sand filters, and pre-coating filters, Pulsfilter consolidates these into a single step.
The system employs a short, automatic back-pulse cleaning cycle that effectively removes deposits, allowing continuous operation without manual intervention.
This technology has already demonstrated excellent results in the chlor-alkali industry and is now being adapted for pulp applications—where it shows significant potential for cadmium removal. By optimizing pH, temperature, and pressure, the filter can efficiently separate heavy metals from process streams, reducing emissions and improving control over metal concentrations.
Noram also applies this technology in its PDP (Precipitator Dust Purification) process, primarily designed to remove unburned carbon and metal oxides before chloride separation from electrostatic precipitator ash. Pulsfilter has proven highly effective in heavy metal removal, particularly cadmium.
Environmental and Operational Benefits
With Pulsfilter technology, Noram is paving the way toward more sustainable and circular pulp production. By combining proven filtration methods with innovative process solutions, new opportunities arise to reduce environmental impact while improving resource efficiency.
Cadmium removal is not only about purification—it is about regaining control over raw material flows in an increasingly demanding, sustainable industrial future.
Beyond the clear environmental benefits, Pulsfilter offers operational advantages. Its compact design reduces plant footprint and maintenance requirements. Automated cleaning cycles lower operating costs and enhance reliability—critical factors for large-scale implementation in modern pulp mills.
By carefully adjusting pH, temperature, and pressure, the filter achieves efficient separation of heavy metals and cadmium from process and ash solutions, resulting in reduced emissions and improved control of metal concentrations. Cadmium removal rates have been shown to exceed 99%.