title: Pretreatment of pulp mill secondary sludge for high-rate anaerobic conversion to biogas.
abstract: Three pretreatment methods were compared based on their ability to increase the extent and rate of anaerobic bioconversion of pulp mill secondary sludge to biogas. The pretreatment technologies used in these experiments were: (i) thermal pretreatment performed at 170 degrees C; (ii) thermochemical (caustic) pretreatment performed at pH 12 and 140 degrees C; and (iii) sonication performed at 20 kHz and 1 W mL(-1). Sludge samples were obtained from a sulfite and a kraft pulp mill, and biochemical methane potential (BMP) assays were performed using microbial granules obtained from a high-rate anaerobic digester operating at a pulp mill. Biogas production from untreated sludge was 0.05 mL mg(-1) of measured chemical oxygen demand (COD) and 0.20 mL mg(-1) COD for kraft and sulfite sludge, respectively. Thermal pretreatment had the highest impact on sludge biodegradability. In this case, biogas yield and production rate from sulfite sludge increased by 50% and 10 times, respectively, while biogas yield and production rate from kraft sludge increased by 280% and 300 times, respectively. Biogas yield correlated to soluble carbohydrate content better than soluble COD.
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S 3E5.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Wood
authors.forename: Honghi
authors.initials: H
authors.lastname: Tran
authors.forename: Emma
authors.initials: E
authors.lastname: Master
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D005740:Gases; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008697:Methane / Q000378:metabolism; D012722:Sewage / Q000737:chemistry*; D013010:Sonication; D013447:Sulfites / Q000032:analysis; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D005740:Gases; D007220:Industrial Waste; D012722:Sewage; D013447:Sulfites; D002244:Carbon; D008697:Methane