Separation of lignin in kraft cooking liquor from a continuous digester by ultrafiltration at temperatures above 100 degrees C
Lignin was extracted by ultrafiltration from kraft cooking liquors taken directly from a continuous digester. The temperature of the liquors was 145 degrees C (softwood) or 135 degrees C (hardwood), the total dry solids content was 18% and the pH 13-14. Methods for start-up, shut-down and cleaning of conventional UF equipment modified for this demanding application, were developed. The influence o
