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The effect of alternating influent carbon source composition on activated sludge bioflocculation

Paper ID Volume ID Publish Year Pages File Format Full-Text
23504 43444 2013 10 PDF Available
Title
The effect of alternating influent carbon source composition on activated sludge bioflocculation
Abstract

•4 activated sludge reactors were subjected to alternating influent carbon sources.•Link between influent characteristics and activated sludge bioflocculation was studied.•Decreased settleability and deflocculation was observed in all four reactors.•Increased hydrolytic activity of eEPSPN results in release of primary particles.•eEPS swelling resulted in an increase in floc size and decreased settleability.

The impact of alternating influent carbon sources, i.e., glucose and starch, on activated sludge bioflocculation was investigated. To this end, four lab-scale reactors were operated during a long-term experiment. During this period the influent carbon source ratio (glucose/starch) was alternated every 7 or 35 days (i.e., a fast and slow switching frequency). Bioflocculation was monitored throughout the entire experiment using an extensive set of parameters, including macroscopic and microscopic activated sludge characteristics. Sludge hydrophobicity remained high (>80%) throughout the experiment indicating good bioflocculation. However, sludge settleability decreased for all four reactors after a 60 day adaptation period to the applied alternation in influent carbon source. During this adaptation period, floc size decreased due to the release of microcolonies. The subsequent period was characterized by a decrease in settleability, coinciding with a release of primary particles and an increase in floc size. The observed phenomena could be linked with the protein concentration near the floc surface. This fraction mainly consists of hydrolytic enzymes necessary for the degradation of starch and is responsible for a progressive deterioration of the EPS matrix. The results of this specific study indicate to be independent of the influent carbon source ratio or switching frequency.

Keywords
Activated sludge; Bioflocculation; Floc structure; Extracellular polymeric substances; Hydrophobicity
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The effect of alternating influent carbon source composition on activated sludge bioflocculation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 167, Issue 3, 10 September 2013, Pages 225–234
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us