Membranes for lignin and hemicellulose recovery in pulp mills

Numerous applications of membrane processes are feasible in pulp mills. The challenges inherent in these applications vary. High pH and high temperature call for ceramic membranes when treating spent pulping liquors, whereas low-cost membranes are needed when treating dilute process streams in mechanical pulp mills. Ultrafiltration has been used to recover lignosulphonate in sulphite pulp mills for more than 30. years. No commercial membrane installations exist to date for the recovery of hemicelluloses and lignin in kraft and mechanical pulp mills. However, recovery of lignin from kraft black liquor, and galactoglucomannan from thermomechanical pulp mill wastewater are current hot topics.