Experimental evaluation of decrease in bacterial activity due to cell death and activity decay in activated sludge

Hao, Xiaodi, Wang, Qilin, Zhang, Xiangping, Cao, Yali and van Mark Loosdrecht, C. M. (2009) Experimental evaluation of decrease in bacterial activity due to cell death and activity decay in activated sludge. Water Research, 43 14: 3604-3612. doi:10.1016/j.watres.2009.05.019


Author Hao, Xiaodi
Wang, Qilin
Zhang, Xiangping
Cao, Yali
van Mark Loosdrecht, C. M.
Title Experimental evaluation of decrease in bacterial activity due to cell death and activity decay in activated sludge
Journal name Water Research   Check publisher's open access policy
ISSN 0043-1354
1879-2448
Publication date 2009-01-01
Sub-type Article (original research)
DOI 10.1016/j.watres.2009.05.019
Open Access Status Not Open Access
Volume 43
Issue 14
Start page 3604
End page 3612
Total pages 9
Place of publication London, United Kingdom
Publisher I W A Publishing
Subject 2312 Water Science and Technology
2311 Waste Management and Disposal
2310 Pollution
2302 Ecological Modelling
Abstract Decrease in bacterial activity (cell decay) in activated sludge can be attributed to cell death (reduction in the amount of active bacteria) and activity decay (reduction in the specific activity of active bacteria). The aim of this study was to experimentally differentiate between cell death and activity decay as a source of decrease in microbial activity. By means of measuring maximal oxygen uptake rates, verifying membrane integrity by live/dead staining and verifying presence of 16S rRNA with fluorescence in-situ hybridization, the decay rates and the death rates of ammonium oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and ordinary heterotrophic organisms (OHOs) were determined respectively in a nitrifying sequencing batch reactor (SBR) and a heterotrophic SBR. The experiments revealed that in the nitrifying system activity decay contributed 47% and 82% to the decreased activities of AOB and NOB and that cell death was responsible for 53% and 18% of decreases in their respective activities. In the heterotrophic system, activity decay took a share of 78% in the decreased activity of OHOs, and cell death was only responsible for 22% of decrease in their activity. The difference between the importance of cell death on the decreased activities of AOB and OHOs might be caused by the mechanisms of substrate storage and/or cryptic growth/death-regeneration of OHOs. The different nutrient sources for AOB and NOB might be the reason for a relatively smaller fraction of cell death in NOB.
Keyword Activity decay
Cell death
Decay rate
Fluorescence in-situ hybridization (FISH)
Live/dead staining
Oxygen uptake rate (OUR)
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Advanced Water Management Centre Publications
 
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