An assessment of side-stream generation from Finnish forest industry

This study examined side-stream generation from Finnish forest industry comprising data from 19 sawmills, 1 plywood mill, 1 particleboard mill, 10 paper and board mills, 1 semi-mechanical mill, and 15 chemical pulp mills. A structured questionnaire survey was carried out for this study. The results revealed that the generation of side stream in sawmills, plywood mills, paper and board mills, mechanical pulp mills, and chemical pulp mills accounted for 42.2%, 56.1%, 23.8%, 30.7%, and 56% of round wood log input, respectively, and 91.2%, 135.5%, 42.2%, 44.7%, and 238.5% of the finished product, respectively. Woodchips, sawdust, and bark were recognized as the significant side streams in sawmills and plywood mills, whereas fiber sludge was found the main side stream in paper, board and mechanical pulp mills. In chemical pulp mills, black liquor was found the greatest side stream, which comprises 43% of the wood input and 183.3% of the finished product. The study estimated that in 2016, Finnish forest industry generated a total 27.7 million tons of side streams, consisting of 49.2% black liquor, 28.5% solid wood-based waste, 14.1% sludge, 4.4% ashes, and 3.8% others. A current use of these side streams and their future utilization potential is also discussed.