Journal
PROCESS BIOCHEMISTRY
Volume 44, Issue 1, Pages 91-96Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.procbio.2008.09.010
Keywords
Activated sludge; Bioflocculation; Dewaterability; Extracellular polymeric substances (EPS); Sedimentation; Non-steady-state condition
Categories
Funding
- Research Grants Council (RGC) of the Hong Kong SAR Government, China [HKU7114/04E, N-HKU737/04]
Ask authors/readers for more resources
Laboratory experiments were carried out on activated sludge (AS) to investigate the correlations between the content of extracellular polymeric Substances (EPS) and the performance of biosolids-water separation, including sludge flocculation, sedimentation, compression, and dewatering, under non-steady-state conditions. On three stabilized AS reactors changes were made in sludge retention time (SRT), substrate composition, and loading rate, respectively, to bring about unstable operation to the reactors. A two-step heating method was used to extract from the sludge the easily extractable EPS, or loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS), respectively. The experimental results demonstrate dynamic changes in sludge characteristic and EPS production under the non-steady-state conditions. During the early phase of transition after a change was imposed, the sludge became generally worse in flocculation, compressibility, and dewaterability. With the acclimatization of the biomass to the new process conditions, biosolids-water separation showed a general trend of improvement. Changes in AS process condition also resulted in considerable variations in EPS production. The change of the LB-EPS content appeared to be more significant than that of the TB-EPS. Throughout the non-steady-state operation, the sludge flocculating behavior, settleability, compressibility, and dewaterability had a positive correlation with the LB-EPS content: however, no correlation could be found between these properties and the TB-EPS content. The results suggest that although EPS is essential to biofloc formation, excessive EPS in the form of LB-EPS would weaken cell attachment and deteriorate the AS floc structure, resulting in poor biosolids-water separation. (C) 2008 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available