Factors contributing to improved environmental performance in the Finnish kraft pulping industry

This study describes the environmental significance of kraft pulping technology developments in Finnish kraft pulp mills. Data on kraft production technology and process energy were collected directly from seven mills. Results are presented as an average of these data. The study presents the main interactions between technology development and environmental performance, particularly water emissions, air emissions, and energy. Supporting technology (e.g., waste treatment operations) and core technology (e.g., liquor processing) were found to be equally important in reducing the environmental loads from kraft pulp mills. The most important supporting technologies are well-operated activated sludge treatment plants and various purification techniques for air emissions. The most important core technologies include dry debarking, oxygen delignification, improved black liquor concentration, and lime mud drying. Wastewater volume has less effect on releases of chemical oxygen demand (COD) than expected. Energy balances are highly dependent on the age of the mill and on whether the pulping and papermaking operations are integrated. Energy balances are usually unaffected by single technology developments.