Recycling industrial residue streams into a potential new symbiosis product - The case of soil amelioration granules

The forest products industry generates several residues in addition to actual products and many of these residues such as fly ash generated by bioenergy production and sludge from the waste water purification processes can be used after being properly treated. This study focused on a hypothetical case in which fly ash from bioenergy production and sludge from forest products industry waste water treatment would be granulated and produced into a forest fertilizer. The Waste Policy of the European Union and growing focus on circular economy goals both support more efficient use of industrial waste and side products and is a major driver for companies towards better material efficiency. This study assessed the global warming potential (GWP) of a potential symbiosis product based on a hypothetical granulating process including two industrial residue streams and briefly examined the drivers of the EU and Finnish policy and legal frameworks for recycling of industrial residues and for their usage as secondary raw materials for potential symbiosis products. The results indicated that the production of 1000 kg of potential symbiosis granules in our model case produced GWP burdens of 11.75 (kg CO2-equiv.). As an example, the production of the already existing NPK-fertilizers produced a GWP burden of 1304.92 (kg CO2-equiv.). Our system boundary was the actual manufacturing process. We also compared different fertilizers based on their fertilizer effect including determination of the composition of the elements in relation to the commercial fertilizer composition. The results indicate that even if the amount of the granulated ash fertilizer was bigger, the amount of environmental burden it produced was much lower. Therefore, the production of the potential symbiosis product could have benefits in terms of GWP results and overall environmental performance when compared to use of primary raw materials. (C) 2016 Elsevier Ltd. All rights reserved.