METHOD OF PREPARATION OF COOKING LIQUID FOR PRODUCTION OF FIBROUS INTERMEDIATE PRODUCT Russian patent published in 1997 - IPC

FIELD: production of fibrous intermediate product; methods of preparation of cooking liquor. SUBSTANCE: the offered method includes saturation with sulfurous anhydride of solution of sodium carbonate in sewage water from biological treatment of industrial sewage of wood-pulp and paper production with concentration of excess activated sludge of 18-40 g/l having concentration of sodium carbonate of 1.55-2.50 mas.% (in terms of Na₂O), or alkaline hydrolyzate produced by treatment of sewage water from biological treatment of industrial sewage of wood-pulp and paper production with concentration of excess activated sludge of 18-40 g/l with mixed base containing 50-80 mas.% of sodium carbonate and 10-50 mas.% (in terms of Na₂O) at temperature of 25-40 C with subsequent removal of formed solid precipitation. Saturation with sulfurous anhydride is carried out at temperature of 35-45 C up to its amount in cooking liquor of 2.5-5.5 mas.%. EFFECT: higher efficiency. 1 tbl