Pre-acidification greatly improved granules physicochemical properties and operational stability of Upflow anaerobic sludge Blanket (UASB) reactor treating low-strength starch wastewater

[Display omitted] •Two UASB processes were compared in the treatment of low-strength starch wastewater.•Granules floatation and disintegration occurred in the One-stage UASB.•Gelatinous attachment to the granules exerted harmful effects on process stability.•The pre-acidification was beneficial for...

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Bibliographic Details
Published in:Bioresource technology 2020-04, Vol.302, p.122810-122810, Article 122810
Main Authors: Wu, Jiang, Jiang, Bo, Feng, Bo, Li, Lu, Moideen, Siti Nur Fatihah, Chen, Hong, Mribet, Chaimaa, Li, Yu-You
Format: Article
Language:English
Subjects:
Anaerobiosis
Bioreactors
Bound EPS
Granular sludge floatation
Hydrogen-Ion Concentration
Pre-acidification
Sewage
Starch
Starch wastewater
UASB reactor
Waste Disposal, Fluid
Waste Water
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Summary:[Display omitted] •Two UASB processes were compared in the treatment of low-strength starch wastewater.•Granules floatation and disintegration occurred in the One-stage UASB.•Gelatinous attachment to the granules exerted harmful effects on process stability.•The pre-acidification was beneficial for the stabilization of the granular sludge. A two-stage process consisting of a pre-acidification unit and an Upflow Anaerobic Sludge Blanket (UASB) reactor (UASBT-S) was compared with a one-stage UASB reactor (UASBO-S) to evaluate the treatment stability of starch wastewater (SW). The Two-stage process provided higher treatment stability than UASBO-S. Sludge floatation occurred in the UASBO-S when the organic loading rate (OLR) was increased to 4 g-COD/L/d, beyond which a paste-like membrane structure adhered to the granules was observed. Further analysis suggests that the substrate derived polysaccharide components embedded in the loosely-bound extracellular polymeric substances (LB-EPS), triggered significant increase in the protein/polysaccharide ratio in the tightly-bound EPS (TB-EPS), and was suggested to result in the granules floatation and disintegration. During the pre-acidification, the starch was mainly converted to acetic and propionic acids. The pre-acidification was beneficial for reducing the EPS content fluctuations in the UASBT-S, which greatly improved settling capability and strength of the granular sludge.
ISSN:0960-8524
1873-2976
DOI:10.1016/j.biortech.2020.122810