In this study, life cycle assessment has been applied to analyse the environmental impacts from a novel technology to recycle textile waste developed within the project RE:Spin. This technology allows for the dissolution of textile fibres and re-spinning them into new fibres within the same process setting, reducing the amount of process steps and increasing efficiency. The goal of this life cycle assessment is to analyse and quantify the potential environmental impacts of the RE:Spin process, to validate the hypothesis that the technology can potentially reduce the environmental impacts of chemical recycling. A secondary goal of the study is to identify hotspots as knowledge support for further developments. The study has a cradle-to-gate scope; and includes the processes of shredding, dissolution, filtration, coagulation, washing and drying. The study also includes support processes for recovery and recirculation of solvents and chemicals. The inventory data has been provided by the project partners, consisting only of lab-scale data from the tests and experiments carried out within the project. This data has been complemented by industrial scale simulations using a specialized software called WinGEMS, which provided mass balances and material flows for the system while energy use was calculated separately. The study analysed all the environmental impact categories required in the environmental footprint 3.1 framework. The results indicate that the RE:Spin technology has the potential to reduce the environmental impact of chemical recycling of cellulosic fibres. The potential environmental impacts from the RE:Spin fibres seem to achieve reductions in most impact categories in reference to conventional fibres, as well as in reference to the results obtained in other studies for chemical recycling of cotton. However, this outcome depends on certain key assumptions, such as the foreground system for ethanol production and heat generation. The most important aspect to focus on for future developments is to ensure a high recovery and recirculation rate of ethanol, sodium hydroxide and hydrochloric acid; which can potentially reduce the environmental impact from the RE:Spin process even further, while avoiding emissions of losses to air and water.

Material recycling requires solutions that are technically, as well as economically and ecologically, viable. In this work, the technical feasibility to separate textile blends of viscose and polyester using alkaline hydrolysis is demonstrated. Polyester is depolymerized into the monomer terephthalic acid at high yields, while viscose is recovered in a polymeric form. After the alkaline treatment, the intrinsic viscosity of cellulose is decreased by up to 35%, which means it may not be suitable for conventional fiber-to-fiber recycling; however, it might be attractive in other technologies, such as emerging fiber processes, or as raw material for sugar platforms. Further, we present an upscaled industrial process layout, which is used to pinpoint the areas of the proposed process that require further optimization. The NaOH economy is identified as the key to an economically viable process, and several recommendations are given to decrease the consumption of NaOH. To further enhance the ecological end economic feasibility of the process, an increased hydrolysis rate and integration with a pulp mill are suggested.

Lignin-based carbon fibres may replace both glass fibres and fossil-based carbon fibres. The objective of this study was to determine the environmental impact of the production of lignin-based carbon fibres using life cycle assessment. The life cycle assessment was done from cradle to gate and followed an attributional approach. The climate impact per kg of lignin- based carbon fibres produced was 1.50 kg CO2,eq. In comparison to glass fibres, the climate impact was reduced by 32% and the climate impact of fossil-based carbon fibres was an order of magnitude higher. A prospective analysis, in which the background energy system was cleaner, showed that the environmental impact of lignin-based carbon fibres will decrease and outperform the glass fibres and fossil-based carbon fibres from a climate impact point-of-view. The constructed LCA model can be applied in further studies of products that consist of or use lignin-based carbon fibres.

Pulp mills producing hardwood and softwood pulp in campaigns have constantly changing process stream compositions. There is aneed to know how these variations develop during the campaigns and that was the objective of this study. A dynamic model, built in the simulation program WinGEMS, has been created by including tanks and reactors with known residence times. A case with a mill producing softwood and hardwood pulp in campaigns has been designed and studied. Some of the studied parameters were white liquor concentration, recovery boiler load and composition of weak black liquor. The dynamic changes of these parameters were not unexpected; however, the time responses and magnitude of these changes were of bigger interest. For instance, it took a little more than 3 days, from the start of a new campaign, to totally replace the weak black liquor from one wood species with the other. In order to interpret results successfully, it was necessary to be aware of the residence time between certain positions in the pulp mill model.