LignoBoost works in conjunction with evaporation.
Black liquor is taken from the evaporation plant and the pH is lowered with CO2. The precipitated lignin is then dewatered using a filter press. LignoBoost then overcomes conventional filtering and sodium separation problems by redissolving the lignin in spent wash water and acid. The resulting slurry is once again dewatered and washed, with acidified wash water, to produce virtually pure lignin cakes. The lignin lean liquor is returned to the liquor cycle.