title: Low-temperature thermal pre-treatment of municipal wastewater sludge: Process optimization and effects on solubilization and anaerobic degradation.
abstract: The present study examines the relationship between the degree of solubilization and biodegradability of wastewater sludge in anaerobic digestion as a result of low-temperature thermal pre-treatment. The main effect of thermal pre-treatment is the disintegration of cell membranes and thus solubilization of organic compounds. There is an established correlation between chemical oxygen demand (COD) solubilization and temperature of thermal pre-treatment, but results of thermal pre-treatment in terms of biodegradability are not well understood. Aiming to determine the impact of low temperature treatments on biogas production, the thermal pre-treatment process was first optimized based on an experimental design study on waste activated sludge in batch mode. The optimum temperature, reaction time and pH of the process were determined to be 80 °C, 5 h and pH 10, respectively. All three factors had a strong individual effect (p < 0.001), with a significant interaction effect for temp. pH2(p = 0.002). Thermal pre-treatments, carried out on seven different municipal wastewater sludges at the above optimum operating conditions, produced increased COD solubilization of 18.3 ± 7.5% and VSS reduction of 27.7 ± 12.3% compared to the untreated sludges. The solubilization of proteins was significantly higher than carbohydrates. Methane produced in biochemical methane potential (BMP) tests, indicated initial higher rates (p = 0.0013) for the thermally treated samples (khydup to 5 times higher), although the ultimate methane yields were not significantly affected by the treatment.
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada.
authors.forename: Laleh
authors.initials: L
authors.lastname: Nazari
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada.
authors.forename: Zhongshun
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada; Trojan Technologies, London, ON, N5V 4T7, Canada.
authors.forename: Domenico
authors.initials: D
authors.lastname: Santoro
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada; Trojan Technologies, London, ON, N5V 4T7, Canada.
authors.forename: Siva
authors.initials: S
authors.lastname: Sarathy
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada; Trojan Technologies, London, ON, N5V 4T7, Canada.
authors.forename: Dang
authors.initials: D
authors.lastname: Ho
authors.affiliation: Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: Damien
authors.initials: D
authors.lastname: Batstone
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada. Electronic address: cxu6@uwo.ca.
authors.forename: Chunbao Charles
authors.initials: CC
authors.lastname: Xu
authors.affiliation: Department of Chemical & Biochemical Eng., Western University, London, ON, N6A 5B9, Canada. Electronic address: mbhowmic@uwo.ca.
authors.forename: Madhumita B
authors.initials: MB
authors.lastname: Ray
mesh_terms: D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D008697:Methane / Q000378:metabolism; D012722:Sewage / Q000737:chemistry*; D013696:Temperature; D062065:Wastewater
chemical_list: D008697:Methane; D012722:Sewage; D062065:Wastewater
keywords: Degradability; Methane production rate; Process optimization; Solubilization; Thermal treatment; Waste activated sludge