Assimilable Organic Carbon (<scp>AOC</scp>) in Treated Water: Determination and Significance

Kooij, D. van der

doi:10.1002/0471263397.env175

Cited by 18 publications

(24 citation statements)

References 62 publications

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“…A difference of less than ±10 % in the mean AOC values was deemed acceptable for use. AOC (mg l 21 ) is estimated from cell concentrations (cells l 21 ) using a theoretical conversion factor (Hammes et al, 2006;Van der Kooij, 2002); we will henceforth use the term 'apparent AOC' (AOC app ) to express the data obtained with this method (equation 1). All assays were performed in triplicate.…”

Section: Methodsmentioning

confidence: 99%

Growth of Vibrio cholerae O1 Ogawa Eltor in freshwater

et al. 2007

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Growth of Vibrio cholerae O1 Ogawa Eltor was studied with a growth assay in which autoclaved and filtered (0.22 mm) freshwater was inoculated at low cell density (5¾10 3 cells ml "1 ) and proliferation was followed with flow cytometry. Against the common view, V. cholerae was able to grow extensively in different kinds of freshwater. The bacterium multiplied in river water, lake water and effluent of a wastewater treatment plant up to a cell density of 1.55¾10 6 cells ml "1 . In these samples, apparent assimilable organic carbon (AOC app ) concentrations ranged from 52 up to 800 mg l "1 and the results demonstrate a positive trend between the AOC app concentration and final cell concentration, suggesting that AOC was a key parameter governing growth of V. cholerae. No growth was observed in waters (tap and bottled drinking water) containing less than approximately 60 mg AOC app l "1 . When pure cultures of V. cholerae were grown on identical lake water at different temperatures (20, 25 and 30 6C) the maximum specific growth rates (m max ) achieved were 0.22 h "1 , 0.32 h "1 and 0.45 h "1 , respectively. In addition, growth was characterized in lake water samples amended with different concentrations of NaCl. The highest m max of V. cholerae was recorded at moderate salinity levels (5 g NaCl l "1 , m max 50.84 h "1 ), whereas at 30 g NaCl l "1 (m max 50.30 h "1 ) or 0 g NaCl l "1 (m max 50.40 h "1 ) specific growth rates were significantly reduced. In the water tested here, m max of V. cholerae was always around 50 % of that exhibited by a freshwater community of indigenous bacteria enriched from the water sampling site. Direct batch competition experiments between V. cholerae and the lake water bacterial community were performed at different temperatures in which V. cholerae was enumerated in the total community using fluorescent-surface antibodies. In all cases V. cholerae was able to grow and constituted around 10 % of the final total cell concentration of the community. No significant effect of temperature was observed on the outcome of the competition. Mathematical modelling of the competition at the different temperatures based on the calculated m max values confirmed these experimental observations. The results demonstrate that V. cholerae is not only able to survive, but also able to grow in freshwater samples. In these experiments the bacterium was able to use a large fraction (12-62 %) of the AOC app available to the bacterial AOC-test community, indicating that V. cholerae has the ability to gain access to the substrates present in freshwater even in competition with an autochthonous bacterial lake water consortium.

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Section: Methodsmentioning

confidence: 99%

Growth of Vibrio cholerae O1 Ogawa Eltor in freshwater

et al. 2007

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“…However, residual chlorine is often depleted in distribution systems . In the absence of residual chlorine, limited biodegradable organic matter (BOM) (Van der Kooij, 1992;Escobar et al, 2001) or nutrients (e.g., phosphorus) (Miettinen et al, 1997;Sathasivan et al, 1997) can prevent extensive microbial regrowth. For reclaimed water, organic matter was found to be the limiting factor (Funamizu et al, 1998), and it was most likely utilized by microorganisms in distribution systems .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of microbial regrowth potential by assimilable organic carbon in various reclaimed water and distribution systems

et al. 2013

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“…Natural organic matter in water comprises a broad spectrum of many different compounds; it is usually determined as a bulk parameter, such as dissolved organic carbon (DOC). Only a fraction (0.1 to 44%) of this DOC pool is readily available for bacterial growth (18,33). This bioavailable fraction is quantified using bioassays, such as the biodegradable dissolved organic carbon (BDOC) assay (27) or the assimilable organic carbon (AOC) assay (31).…”

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confidence: 99%

“…Moreover, the spectrum of growth-supporting substrates (carbon compounds) of individual bacterial strains is specific-a fact also used for the classification of bacteria for taxonomic purposes. This principle has been integrated into conventional AOC assays, where the specific substrate spectrum of different pure cultures can be used to quantify different types of compounds present in water (26,33). The term "pathogenic bacteria" is a collective term for many different bacterial species that can all cause disease in humans but their individual substrate spectra are unique for each species.…”

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Evaluating the Growth Potential of Pathogenic Bacteria in Water

Vital

Stucki

Egli

et al. 2010

Appl Environ Microbiol

100

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The degree to which a water sample can potentially support the growth of human pathogens was evaluated. For this purpose, a pathogen growth potential (PGP) bioassay was developed based on the principles of conventional assimilable organic carbon (AOC) determination, but using pure cultures of selected pathogenic bacteria (Escherichia coli O157, Vibrio cholerae, or Pseudomonas aeruginosa) as the inoculum. We evaluated 19 water samples collected after different treatment steps from two drinking water production plants and a wastewater treatment plant and from ozone-treated river water. Each pathogen was batch grown to stationary phase in sterile water samples, and the concentration of cells produced was measured using flow cytometry. In addition, the fraction of AOC consumed by each pathogen was estimated. Pathogen growth did not correlate with dissolved organic carbon (DOC) concentration and correlated only weakly with the concentration of AOC. Furthermore, the three pathogens never grew to the same final concentration in any water sample, and the relative ratio of the cultures to each other was unique in each sample. These results suggest that the extent of pathogen growth is affected not only by the concentration but also by the composition of AOC. Through this bioassay, PGP can be included as a parameter in water treatment system design, control, and operation. Additionally, a multilevel concept that integrates the results from the bioassay into the bigger framework of pathogen growth in water is discussed. The proposed approach provides a first step for including pathogen growth into microbial risk assessment.Pathogenic bacteria can survive and also grow in lownutrient aquatic environments, such as surface waters or man-made water treatment systems (2,17,30). Studies on pathogen survival and/or die-off (including disinfection) in water are common, but little is known about the fundamental factors governing their growth in the environment (34,35). Understanding the growth of pathogenic bacteria in aquatic ecosystems is essential for a holistic approach to microbial risk assessment as well as for improving drinking water treatment design and operation.

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Assimilable Organic Carbon (AOC) in Treated Water: Determination and Significance

Abstract: Controlling Microbiological Water Quality Regrowth Processes and Growth Kinetics AOC Method AOC Concentrations in Water Biological Stability Acknowledgments

Cited by 18 publications

References 62 publications

Growth of Vibrio cholerae O1 Ogawa Eltor in freshwater

Growth of Vibrio cholerae O1 Ogawa Eltor in freshwater

Evaluation of microbial regrowth potential by assimilable organic carbon in various reclaimed water and distribution systems

Evaluating the Growth Potential of Pathogenic Bacteria in Water

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