title: Enzyme extraction by ultrasound from sludge flocs.
abstract: Enzymes play essential roles in the biological processes of sludge treatment. In this article, the ultrasound method to extract enzymes from sludge flocs was presented. Results showed that using ultrasound method at 20 kHz could extract more types of enzymes than that at 40 kHz and ethylenediamine tetraacetic acid (EDTA) methods. The optimum parameters of ultrasound extraction at 20 kHz were duration of 10 min and intensity of 552 W/g TSS. Under the optimum condition, ultrasound could break the cells and extract both the extracellular and a small part of intercellular enzymes. Ultrasound intensity was apparently more susceptive to enzyme extraction than duration, suggesting that the control of intensity during ultrasound extraction was more important than that of duration. The Pearson correlation analysis between enzyme activities and cation contents revealed that the different types of enzymes had distinct cation binding characteristics.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Yu
authors.forename: Pinjing
authors.initials: P
authors.lastname: He
authors.forename: Liming
authors.initials: L
authors.lastname: Shao
authors.forename: Yishu
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D000332:Aerobiosis; D002412:Cations; D004247:DNA / Q000302:isolation & purification; D004798:Enzymes / Q000302:isolation & purification*; D005427:Flocculation; D019015:Geologic Sediments / Q000737:chemistry; D012722:Sewage; D014465:Ultrasonics
chemical_list: D002412:Cations; D004798:Enzymes; D012722:Sewage; D004247:DNA