Extracellular enzymes in sludge flocs collected at 14 full-scale wastewater treatment plants
Journal
Journal of Chemical Technology and Biotechnology
Journal Volume
83
Journal Issue
12
Pages
1717-1725
Date Issued
2008
Author(s)
Abstract
Background: Extracellular enzymes and chemical composition of sludge flocs affect the wastewater treatment capability. Here a fractionation protocol is presented describing the distributions of extracellular enzymes, proteins (PN) and polysaccharides (PS) in sludge flocs. Sludge floc samples collected from 14 full-scale wastwater treatment plants (WWTPs), including those treating sewage, leachate and industrial wastewaters, were fractionated through centrifugation and ultrasound into five fractions: (1) supernatant; (2) slime; (3) loosely bound extracellular polymeric substances (LB-EPS); (4) tightly bound EPS (TB-EPS); and (5) pellets. Results: The distributions of extracellular enzymes, PN and PS in different types of sludge flocs were almost identical. Considerable quantities of α-amylase were bound with the pellet fraction, while the remainder was uniformly dispersed over the sludge matrix. Conversely, alkaline phosphatase, acid phosphatase and protease bound mainly with the pellet and TB-EPS fractions. Conclusion: The enzyme activities distributed in sludge flocs achieved from 14 full-scale WWTPs revealed a non-wastewater-specific manner. This work for the first time demonstrated that the activities of enzymes correlated with the characteristics of the wastewaters treated, and raised the possibility of manipulating the hydrolysis reactions using process parameters. ? 2008 Society of Chemical Industry.
Subjects
Distribution
Enzyme
Extracellular polymeric substances
Fractioning protocol
Sludge flocs
Type
journal article