1. 1 Stora Enso International Oy, Imatra Research Centre , Tornansaarenraitti 48, FI-55800 Imatra , Finland , phone +358-040-577-3498 ,
2. 2 Department of Environmental Protection , City of Kemi, Valtakatu 26, FI-94100 Kemi , Finland ,
3. 3 Department of Bioproducts and Biosystems, School of Chemical Technology , Aalto University , PO Box 16300, FI-00075 Aalto , Finland ,