A novel, optical, on-line bacteria sensor for monitoring drinking water quality

Højris, Bo; Christensen, Sarah Christine Boesgaard; Albrechtsen, Hans‐Jørgen; Smith, Christian; Dahlqvist, Mathis

doi:10.1038/srep23935

Cited by 81 publications

(55 citation statements)

References 28 publications

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“…Whether the recently emerging online detection systems for TCC enumeration (Besmer et al, , ; Hammes et al, ; Hammes, Berger, Köster, & Egli, ; Van Nevel et al, ) also add significant value to this approach has yet to be evaluated. Irrespective of the applicability of currently emerging technologies, the general importance of microbiological online monitoring and automation (e.g., precipitation event‐triggered automated sampling) is likely to increase in the near future (Besmer et al, ; Højris et al, ; Ryzinska‐Paier et al, ; Stadler et al, ). The application of genetic MST markers also holds great promise for future water quality testing.…”

Section: Conclusion—status Quo and Future Research Needsmentioning

confidence: 99%

Opening the black box of spring water microbiology from alpine karst aquifers to support proactive drinking water resource management

et al. 2018

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Over the past 15 years, pioneering interdisciplinary research has been performed on the microbiology of hydrogeologically well‐defined alpine karst springs located in the Northern Calcareous Alps (NCA) of Austria. This article gives an overview on these activities and links them to other relevant research. Results from the NCA springs and comparable sites revealed that spring water harbors abundant natural microbial communities even in aquifers with high water residence times and the absence of immediate surface influence. Apparently, hydrogeology has a strong impact on the concentration and size of the observed microbes, and total cell counts (TCC) were suggested as a useful means for spring type classification. Measurement of microbial activities at the NCA springs revealed extremely low microbial growth rates in the base flow component of the studied spring waters and indicated the importance of biofilm‐associated microbial activities in sediments and on rock surfaces. Based on genetic analysis, the autochthonous microbial endokarst community (AMEC) versus transient microbial endokarst community (TMEC) concept was proposed for the NCA springs, and further details within this overview article are given to prompt its future evaluation. In this regard, it is well known that during high‐discharge situations, surface‐associated microbes and nutrients such as from soil habitats or human settlements—potentially containing fecal‐associated pathogens as the most critical water‐quality hazard—may be rapidly flushed into vulnerable karst aquifers. In this context, a framework for the comprehensive analysis of microbial pollution has been proposed for the NCA springs to support the sustainable management of drinking water safety in accordance with recent World Health Organization guidelines. Near‐real‐time online water quality monitoring, microbial source tracking (MST) and MST‐guided quantitative microbial‐risk assessment (QMRA) are examples of the proposed analytical tools. In this context, this overview article also provides a short introduction to recently emerging methodologies in microbiological diagnostics to support reading for the practitioner. Finally, the article highlights future research and development needs.This article is categorized under: Engineering Water > Water, Health, and SanitationScience of Water > Water ExtremesWater and Life > Nature of Freshwater Ecosystems

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Section: Conclusion—status Quo and Future Research Needsmentioning

confidence: 99%

Opening the black box of spring water microbiology from alpine karst aquifers to support proactive drinking water resource management

et al. 2018

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“…However, the World Health Organization (WHO) acknowledges that HPC does not link to the health risk in people who are already healthy 19,20 , but HPC bacteria may pose a higher risk for the immunocompromised 21 . HPC only detects a fraction of total bacteria that can grow on the medium (<1% of bacteria) not including viable, but non-culturable bacteria (VBNC) 22,23 . Also, the HPC and total coliform quantification requires 24-48 h to obtain the results, thus preventing early detection of the risks and timely implementation of corrective measures before water distribution 24 .…”

Section: Introductionmentioning

confidence: 99%

“…Online microbial quality monitoring is important for an early warning system, enabling potential risk identification to enforce measures protecting the end-user 24 . The automated systems for online monitoring of bacterial density such as FCM [34][35][36] , ATP analyzer 30 , and optical sensors based on three-dimensional (3D) image recognition 23 have been employed for drinking water. FCM is a bacterial cell-counting tool that incorporates deoxyribonucleic acid (DNA) staining protocols for the assessment and evaluation of bacterial water quality.…”

Section: Introductionmentioning

confidence: 99%

Online characterization of bacterial processes in drinking water systems

2020

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The use of traditional drinking water microbial quality monitoring methods, including heterotrophic plate counts (HPCs) and total coliform counts, are not only laborious and time-consuming but also do not readily allow identification of risk areas in the network. Furthermore, if areas of concern are identified, and mitigation measures are taken, it takes days before the effectiveness of these measures is known. This study identified flow cytometry (FCM) as an online sensor technology for bacterial water quality monitoring in the distribution network. We monitored the total bacterial cell numbers and biodiversity in a drinking water distribution system (DWDS) using an online FCM. Two parallel online FCM monitoring systems were installed on two different locations at a drinking water treatment plant (DWTP; Saudi Arabia) supplying chlorinated water to the distribution and in the network 3.6 km away from the DWTP. The FCMs were operated at the same time in parallel to assess the biological stability in DWDSs. The flow cytometric data was compared with the conventional water quality detection methods (HPC and total coliforms). HPC and total coliforms were constantly below the detection limits, while the FCM provided detectable total cell count data and enabled the quantification of changes in the drinking water both with time and during distribution. Results demonstrate the value of FCM as a tool for compliance monitoring and risk assessment of DWDSs.

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“…One of the greatest challenges for microbiological water quality monitoring is the time needed to investigate the water safety. By the time analysis results are available, the water is in part already distributed and used (Højris et al 2016). This problem especially applies to traditional cultivation-based analysis whose speed is inevitably determined by the growth rate of the microorganism to be counted.…”

Section: Introductionmentioning

confidence: 99%

Flow cytometry-based evaluation of the bacterial removal efficiency of a blackwater reuse treatment plant and the microbiological changes in the associated non-potable distribution network

Whitton

Fane

Jarvis

et al. 2018

Science of The Total Environment

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The study evaluated the changes in bacterial numbers across a full-scale membrane bioreactor (MBR) blackwater reuse system. Flow cytometry was used to quantify total and intact bacterial concentrations across the treatment train and during distribution of the recycled water. Membrane passage reduced bacterial numbers by up to 5-log units resulting in coliform-free permeate. A 2-log increase in bacterial cell concentration was subsequently observed after the granular activated carbon unit followed by a reduction in intact cells after chlorination, which corresponds to an overall intact bacteria removal of 3.4-log units. In the distribution network, the proportion of intact cells greatly depended on the free chlorine residual, with decreasing residual enabling regrowth. An initial target of 0.5 mg L free chlorine ensured sufficient suppression of intact cells for up to 14 days (setting the time intervals for system flushes at times of low water usage). Bacterial regrowth was only observed when the free chlorine concentration was below 0.34 mg L. Such loss of residual chlorine mainly applied to distant points in the distribution network from the blackwater reuse treatment plant (BRTP). Flushing these network points for 5 min did not substantially reduce cell numbers. At points closer to the BRTP, on the other hand, flushing reduced cell numbers by up to 1.5-log units concomitant with a decreasing proportion of intact cells. Intact cell concentrations did not correlate with DOC, total nitrogen, or soluble reactive phosphate, but it was shown that dead biomass could be efficiently converted into new biomass within seven days.

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A novel, optical, on-line bacteria sensor for monitoring drinking water quality

Cited by 81 publications

References 28 publications

Opening the black box of spring water microbiology from alpine karst aquifers to support proactive drinking water resource management

Opening the black box of spring water microbiology from alpine karst aquifers to support proactive drinking water resource management

Online characterization of bacterial processes in drinking water systems

Flow cytometry-based evaluation of the bacterial removal efficiency of a blackwater reuse treatment plant and the microbiological changes in the associated non-potable distribution network

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