title: Microwave, ultrasonic and chemo-mechanical pretreatments for enhancing methane potential of pulp mill wastewater treatment sludge.
abstract: Microwave (2450 MHz, 1250 W), ultrasonic (20 kHz, 400 W) and chemo-mechanical (MicroSludge® with 900 mg/L NaOH followed by 83,000 kPa) pretreatments were applied to pulp mill waste sludge to enhance methane production and reduce digester sludge retention time. The effects of four variables (microwave temperature in a range of 50-175°C) and sonication time (15-90 min), sludge type (primary or secondary) and digester temperature (mesophilic and thermophilic) were investigated. Microwave pretreatment proved to be the most effective, increasing specific methane yields of WAS samples by 90% compared to controls after 21 days of mesophilic digestion. Sonication solubilized the sludge samples better, but resulted in soluble non-biodegradable compounds. Based on the laboratory scale data, MicroSludge® was found the least energy intensive pretreatment followed by sonication for 15 min alternative with net energy profits of 1366 and 386 kWh/tonne of total solids (TS), respectively. Pretreatment benefits were smaller for thermophilic digesters.
authors: School of Engineering, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada V1V 1V7. msaha3@interchange.ubc.ca
authors: Mithun
authors: M
authors: Saha
authors: Cigdem
authors: C
authors: Eskicioglu
authors: Juan
authors: J
authors: Marin
mesh_terms: D000693:Anaerobiosis; D001704:Biopolymers; D008697:Methane / Q000096:biosynthesis*; D008872:Microwaves; D012722:Sewage; D012995:Solubility; D013783:Textile Industry
chemical_list: D001704:Biopolymers; D012722:Sewage; D008697:Methane