title: Interpreting the synergistic effect in combined ultrasonication-ozonation sewage sludge pre-treatment.
abstract: The sequential combination of ultrasonication and ozonation as sewage sludge treatment prior to anaerobic digestion was investigated. Synergistic volatile suspended solids (VSS) solubilization was observed when low energy ultrasonication (⩽12kJg(-1) TS) was followed by ozonation. 0.048gO3g(-1) TS ozonation induced the maximum VSS solubilization of 41.3% when the sludge was pre-ultrasonicated at 9kJg(-1) TS; while, the same ozone dosage applied without prior ultrasonication only induced 21.1% VSS solubilization. High molecular weight (MW) components (MW>500kDa) were found to be the main solubilization products when sludge was only ozonated. However, solubilization products by ozone were mainly in the form of low MW components (MW<27kDa) when sludge was pre-ultrasonicated. The high MW products generated by ultrasound were effectively degraded in the subsequent ozonation. Anaerobic biodegradability increased by 34.7% when ultrasonication (9kJg(-1) TS) and ozonation (0.036gO3g(-1) TS) were combined sequentially. The maximum methane production rate increased from 3.53 to 4.32, 4.21 and 4.54mL CH4d(-1) after ultrasonication, ozonation and ultrasonication-ozonation pre-treatments, respectively.
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Xinbo
authors.initials: X
authors.lastname: Tian
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore.
authors.forename: Chong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore.
authors.forename: Antoine Prandota
authors.initials: AP
authors.lastname: Trzcinski
authors.affiliation: Public Utilities Board, Water Reclamation (Plants) Department, 20 Pioneer Road, Singapore 628507, Singapore.
authors.forename: Leonard
authors.initials: L
authors.lastname: Lin
authors.affiliation: Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. Electronic address: WJNg@ntu.edu.sg.
authors.forename: Wun Jern
authors.initials: WJ
authors.lastname: Ng
mesh_terms: D001673:Biodegradation, Environmental; D010126:Ozone; D012722:Sewage; D014465:Ultrasonics; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D010126:Ozone
keywords: Anaerobic digestion; Molecular weight; Ozone; Pre-treatment; Sewage sludge; Ultrasound