Improved impregnation efficiency and pulp yield of softwood kraft pulp by high effective alkali charge in the impregnation stage
Abstract A pulp yield increase up to 2% can be achieved by impregnation with a liquor containing 2 M effective alkali (EA) concentration instead of 1 M. The yield increase is due to higher cellulose and glucomannan contents in the pulp, which can be rationalized by less yield loss by peeling, as impregnation is more effective at an elevated EA level. A rapid loading of chips with alkali can be realized due to a high diffusion rate. When the temperature becomes higher in the cooking stage, enough alkali is available for delignification reactions without the risk of alkali depletion in the chip core, so that the delignification is more homogeneous.
Extended delignification in kraft cooking through improved selectivity
La difference d'alcalinite a 170 o C entre des solutions contenant de la lignine dissoute et des solutions sans lignine (lessive blanche) a ete determinee indirectement par determination du degre de degradation de la cellulose evalue a partir des changements du degre de polymerisation calcule a partir de mesures de la viscosite intrinseque. Les resultats montrent que l'alcalinite de la solution contenant la lignine augmente avec la temperature
Gill diseases of cultured salmonids in Ontario.
Between 1977 and 1981, the Fish Pathology Laboratory of the Ontario Veterinary College received 239 cases from trout farms of southern Ontario, 51 (21.3%) of which had diseased gills. Branchial lesions in 86.3% of these 51 cases were characterized by marked lamellar epithelial hyperplasia with epithelial hypertrophy and lamellar fusion. Filamentous bacteria were seen on the surface of the branchial filaments and lamellae in 68.6% of the cases. Our observations highlight the importance of gill diseases as a production problem of farmed salmonids in southern Ontario.