June 19-24, 2016
Confronted by a steady decline in the demand for commodity papers, the pulp and paper industry has undertaken intensive R&D efforts to identify and develop new non paper products that could be manufactured from the forest biomass. The components of wood that can be separated and converted into new non paper products are the cellulose, hemicelluloses and lignin. Celluloses and hemicelluloses are polymers of various sugars and lignin is a polymer of phenylpropane units. This paper treats the specific case of lignin and hemicellulose extraction from a Kraft pulping process. Two processes have been investigated for the extraction of lignin from black liquor. One is an enhanced version of precipitation of lignin under low pH conditions achieved by carbonation of Kraft black liquor. The work was focused on the efficiency of the lignin flocculation and filtration steps and on the impact of the black liquor withdrawal on the chemical balance of the Kraft process. The second process focuses on the acidification of the black liquor by electrodialysis with bipolar membrane. This process produces clean lignin and valuable caustic soda. In this case the lignin is easily filtered however partial precipitation of lignin may happen in the eletrodialysis cell. A procedure was developed to avoid the occurrence of counterproductive phenomena. The extraction of hemicelluloses from wood chips and their partitioning into a mixture of C5 and C6 sugars can be accomplished by a two-step hydrolysis. The sugars can then be converted into a large number of derivatives. The case of fermentation into butanol is presented. Innovations were made in the process detoxification and the enhancement of the butanol fermentation. The process developed can be integrated to the Kraft mill from the standpoint of steam and water. The energy intensification of the site eliminates the requirement for fossil fuel thus enhancing the feasibility of the green integrated forest biorefinery.
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Miyuru Kannangara, Mariya Marinova, Michel Perrier, and Jean Paris, "The integrated forest biorefinery, an example of green engineering" in "5th International Congress on Green Process Engineering (GPE 2016)", Franco Berruti, Western University, Canada Cedric Briens, Western University, Canada Eds, ECI Symposium Series, (2016). https://dc.engconfintl.org/gpe2016/12