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Use of waste liquor from bisulfite pulping to produce mixed culture single‐cell protein
Author(s) -
Lo S. N.,
Moreau J. R.,
StLaurent G.
Publication year - 1978
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450560113
Subject(s) - pulp and paper industry , biomass (ecology) , mixed liquor suspended solids , chemistry , pulp (tooth) , single cell protein , activated sludge , waste management , wastewater , aeration , environmental science , food science , fermentation , environmental engineering , biology , organic chemistry , agronomy , medicine , pathology , engineering
The activated sludge process might be used in the very near future to treat the waste liquors from small bisulfite mills in Canada, as a mean of controlling water pollution. These mills produce normally less than 300 t/d of pulp. It was found that the bio‐sludge solids from such a process, when used to treat such waste liquor, contained approximately 38% protein, 47% carbohydrates, some vitamins and sufficient quantities of essential minerals. This bio‐substance, a mixed‐culture in nature, could be considered as a good source of single‐cell protein. The nutritive value in terms of protein efficiency ratio of this substance was tested with rats; good results were obtained when the biomass was slightly supplemented with methionine. Described in this paper is a system used in our laboratory to produce this biomass in a sterile and dried form. The conversion of carbohydrates contained in waste pulping liquor to biomass was carried out in a 400‐l, aerated, continuous‐flow tank reactor. Under the operating conditions studied the sludge yield coefficient was 0.53 g of biomass/g of carbohydrates removed. A cash return study of selling biomass is also presented for two mills producing high‐ and low‐yield pulps respectively.