Effects of ultrasound pretreatment of sludge on anaerobic digestion
Journal
Journal of Residuals Science and Technology
Journal Volume
3
Journal Issue
1
Pages
51-59
Date Issued
2006
Author(s)
Abstract
The effects of low frequency ultrasound on sludge solids disintegration and the feasibility of sonication pretreatment for continuous digester operation were examined in the laboratory. The results suggested that higher sonication intensities are able to Initiate a larger number of transient cavitation bubbles resulting In greater sludge disintegration, which was evidenced by marked particle size reduction and soluble organics enhancement. Comparing the control digester fed with untreated sludge, the chemical oxygen demand (COD) removal increased by 5-32%, 7-51% and 11-59% in the digesters fed with sludge sonicated at intensities of 32 W/cm2,56 W/cm2 and 92 W/cm 2, respectively under continuous operation. The improved COD removal efficiency corresponded with the increase in biogas production by 45-202%, 184-220% and 115-205% In the respective digesters, as well as an overall increase by up to 22% in methane composition. Greater improvement over the control digester was observed at higher organic loading rates (OLRs). Biogas depression was observed from digesters treating sludge sonicated with higher intensities likely caused by the accumulation of excessive volatile fatty acids (VFAs) under continuous digester operation. ? 2006 DEStech Publications, Inc.
Type
journal article