TITLE:
Effect of Combined Microwave-Ultrasonic Pretreatment on Anaerobic Biodegradability of Primary, Excess Activated and Mixed Sludge
AUTHORS:
Anteneh Mesfin Yeneneh, Tushar Kanti Sen, Siewhui Chong, Ha Ming Ang, Ahmet Kayaalp
KEYWORDS:
Biodegradability; Combined Microwave-Ultrasonic; Dewaterability; Primary; Excess Activated Sludge; Mixed Sludge
JOURNAL NAME:
Computational Water, Energy, and Environmental Engineering,
Vol.2 No.3B,
October
24,
2013
ABSTRACT: This work deals with the
effect of combined microwave-ultrasonic pretreatment on the anaerobic
biodegradability of primary, excess activated and mixed sludge. The
characteristics, biodegradability and anaerobic digester performance for
untreated primary, excess activated and mixed sludge were compared to combined
microwave-ultrasonic pretreated primary, excess activated and mixed sludge. All
sludge samples were subjected to Microwave treatment at 2450 MHz, 800 W and 3
min followed by ultrasonic treatment at a density of 0.4 W/mL, amplitude of
90%, Intensity of 150 W, pulse of 55/5 for 6min. Methane production in pretreated primary
sludge was significantly greater (11.9 ml/g
TCOD) than the methane
yield of the untreated primary sludge (7.9 ml/g TCOD). Cumulative methane production of
pretreated Excess Activated Sludge (EAS) was higher (66.5 ml/g TCOD) than the
methane yield from pretreated mixed sludge (44.1 ml/g TCOD). Furthermore,
digested EAS showed significantly higher dewaterability (201 s) than digested primary sludge (305 s) or mixed sludge (522 s). The average Methane:
Carbondioxide ratio from EAS (1.85) was higher than that for mixed untreated
sludge (1.24). VS reduction was also higher for EAS than the other two sludge
types. However, pretreatment of EAS resulted in significant reduction in
dewaterability due to higher percentage of fine floc particles in the
pretreated EAS.