title: Paper sludge (PS) to bioethanol: Evaluation of virgin and recycle mill sludge for low enzyme, high-solids fermentation.
abstract: Paper sludge (PS) from the paper and pulp industry consists primarily of cellulose and ash and has significant potential for ethanol production. Thirty-seven PS samples from 11 South African paper and pulp mills exhibited large variation in chemical composition and resulting ethanol production. Simultaneous saccharification and fermentation (SSF) of PS in fed-batch culture was investigated at high solid loadings and low enzyme dosages. Water holding capacity and viscosity of the PS influenced ethanol production at elevated solid loadings of PS. High viscosity of PS from virgin pulp mills restricted the solid loading to 18% (w/w) at an enzyme dosage of 20 FPU/gram dry PS (gdPS), whereas an optimal solid loading of 27% (w/w) was achieved with corrugated recycle mill PS at 11 FPU/gdPS. Ethanol concentration and yield of virgin pulp and corrugated recycle PS were 34.2g/L at 66.9% and 45.5 g/L at 78.2%, respectively.
authors.affiliation: Department of Process Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Sonja
authors.initials: S
authors.lastname: Boshoff
authors.affiliation: Department of Process Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Lalitha Devi
authors.initials: LD
authors.lastname: Gottumukkala
authors.affiliation: Department of Process Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Eugéne
authors.initials: E
authors.lastname: van Rensburg
authors.affiliation: Department of Process Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa. Electronic address: jgorgens@sun.ac.za.
authors.forename: Johann
authors.initials: J
authors.lastname: Görgens
mesh_terms: D061249:Batch Cell Culture Techniques; D056804:Biofuels; D002482:Cellulose / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D007220:Industrial Waste / Q000032:analysis*; D010209:Paper; D059027:Recycling
chemical_list: D056804:Biofuels; D007220:Industrial Waste; D000431:Ethanol; D002482:Cellulose
keywords: Bioethanol; Fed-batch culture; High-solids fermentation; Paper sludge; Simultaneous saccharification and fermentation