Thiothrix Eikelboomii Interferes Oxygen Transfer in Activated Sludge
Abstract
This study revealed that, Thiothrix eikelboomii, a well-known filamentous bacterium that causes sludge bulking, could also interfere oxygen transfer during wastewater treatment. The volumetric oxygen transfer coefficient (KLa) in filamentous-bulking sludge (FBS) was found to be 43% lower than that in floc-forming sludge (FFS) at similar biomass concentrations, partially because the filamentous bacteria had increased the sludge apparent viscosity. The KLa value for FBS, however, was still significantly lower than that for FFS even if both sludges had similar apparent viscosity. Numerous tiny and free-swimming filaments were observed to attach on the air bubble surface, presumably reducing the liquid film renewal and increasing the liquid film thickness. Moreover, the filaments were co-coated with extracellular polymeric substances of protein and polysaccharide, which could make them performing like "amphiphilic molecules" of surfactants to hinder oxygen transfer. Therefore, the particular surface property of filaments and their interaction with air bubbles could also impact oxygen transfer. Thiothrix eikelboomii was identified to be the responsible filamentous bacterium that lowered the KLa value, while other filamentous bacteria with short filaments did not interfere oxygen transfer. This study implies that controlling sludge bulking benefits not only sludge settling but also oxygen transfer.
Recommended Citation
X. Wu et al., "Thiothrix Eikelboomii Interferes Oxygen Transfer in Activated Sludge," Water Research, vol. 151, pp. 134 - 143, Elsevier Ltd, Mar 2019.
The definitive version is available at https://doi.org/10.1016/j.watres.2018.12.019
Department(s)
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Activated sludge; Filamentous bulking; Oxygen transfer; Thiothrix; Wastewater treatment
International Standard Serial Number (ISSN)
0043-1354
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2019 Elsevier Ltd, All rights reserved.
Publication Date
01 Mar 2019
Comments
This research was supported by grants from the Chinese National Natural Science Foundation (51608230), the Water Resource Science and Technology Innovation Program of Guangdong Province (201628), Guangzhou Science and Technology program (201704020138 ; 201804020050), the Fundamental Research Funds for the Central Universities (21616335).