The cyclic treatment was designed that lignin is removed from alkali pulp waste liquor by passing SO2 gas, the filtrate is used as cooking liquor of semichemical pulp and the semichemical pulp waste liquor is concentrated and burned with removed lignin, the resulting smelt is used as cooking liquor of alkali pulp.
This report is explained the effect of pH variation (acidic to neutral) of reproduced cooking liquor from soda pulp waste liquor on chemical properties of semichemical pulp.