Bacterial community dynamics and disinfection impact in cooling water systems

Pinel, Ingrid; Moed, D.H.; Vrouwenvelder, Johannes S.; Loosdrecht, Mark C.M. van

doi:10.1016/j.watres.2020.115505

Cited by 38 publications

(20 citation statements)

References 45 publications

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“…Here we have built on prior work by demonstrating that FCM can also be useful for identifying cases where biocide dosing can be further optimised. In concordance with recently published work 24 , we also found that standard oxidative biocide dosing does not completely inactivate cooling tower communities (even when dosed at the highest permissible concentrations). It must be noted that it is well established that biofilms confer to their resident communities a degree of protection against biocides, relative to their planktonic counterparts 25 – 27 .…”

Section: Discussionsupporting

confidence: 92%

Computational flow cytometry of planktonic populations for the evaluation of microbiological-control programs in district cooling plants

McElhinney

Mawart

Alkaabi

et al. 2020

Sci Rep

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Biofouling poses a serious concern for the district cooling (Dc) industry. current industry practises for monitoring biofouling continue to rely on culture-based methods for microbial enumeration, which are ultimately flawed. Computational flow cytometric (cFCM) analyses, which offer enhanced reproducibility and streamlined analytics versus conventional flow cytometry were applied to samples taken from 3 sites in each of 3 plants over a 5-week sampling program. We asked whether the application of cfcM to monitoring planktonic community dynamics in Dc plants could be able to provide sufficient information to enhance microbiological-control strategies at site and inform about plant performance impacts. the use of cfcM enabled the evaluation of biocide dosing, deep cleaning treatment efficiencies and routes of microbial ingress into the studied systems. Additionally, inherent risks arising from the reintroduction of microbiological communities into recently cleaned Wct basins from contaminated cooling waters were identified. However, short-term dynamics did not relate with plant performance metrics. In summary, the insights offered by this approach can inform on plant status, enable evaluations of microbial loads during biofouling mitigation programs and, ultimately, enhance industry management of the biofouling process. Hot urban climates requires extensive cooling to provide habitable indoor environments and high demand in electricity and water use. Centralized production and distribution of cooling waters from district cooling plants (DCPs) is the preferred means of providing cooling waters for industrial, commercial and residential use as it is generally more economical than conventional on-site air-based cooling. The current annual energy demand for cooling accounts for 10% of global electricity use and is expected to triple by 2050, largely due to population expansions in developing hot-climate countries, including the Middle East 1. Accordingly, the Gulf Cooperation Council (GCC) has seen a rapid expansion in district cooling facilities to meet airconditioning requirements which are the largest such requirements in the world (in excess of 25,000,000 refrigeration tons (RT) 2). Indeed, the peak consumption in the United Arab Emirates (UAE) is second only to Saudi Arabia in the GCC with the majority of electricity loads (~ 70%) being required for cooling 3. Furthermore, peak cooling demands are forecast to reach 100 M RT in the GCC region by 2030 4. Given the continued expansion of the global population, climate change and lack of alternatives for cooling in high-density urban areas, we can expect a continued reliance on DCPs for the foreseeable future. It is therefore essential that these cooling facilities are operating as efficiently and sustainably as possible in order to meet the demand for cooling, whilst mitigating environmental impacts. District cooling systems are composed of four principle components: a make-up water (MUW) supply line, a centralized Cooling Plant, a chilled water supply network and th...

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Section: Discussionsupporting

confidence: 92%

Computational flow cytometry of planktonic populations for the evaluation of microbiological-control programs in district cooling plants

McElhinney

Mawart

Alkaabi

et al. 2020

Sci Rep

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“…The composition of environmental samples is complex and influences the optimal application of the techniques. For water samples, both from natural water sources (e.g., surface waters or rivers) or anthropogenically-derived (e.g., drinking water systems or household water), most authors concentrate large volumes of water by filtration and/centrifugation [ 114 , 319 ]. Membrane filtration is standardized.…”

Section: Detection Identification and Differentiation Tools For mentioning

confidence: 99%

Non-Tuberculous Mycobacteria: Molecular and Physiological Bases of Virulence and Adaptation to Ecological Niches

et al. 2020

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Non-tuberculous mycobacteria (NTM) are paradigmatic colonizers of the total environment, circulating at the interfaces of the atmosphere, lithosphere, hydrosphere, biosphere, and anthroposphere. Their striking adaptive ecology on the interconnection of multiple spheres results from the combination of several biological features related to their exclusive hydrophobic and lipid-rich impermeable cell wall, transcriptional regulation signatures, biofilm phenotype, and symbiosis with protozoa. This unique blend of traits is reviewed in this work, with highlights to the prodigious plasticity and persistence hallmarks of NTM in a wide diversity of environments, from extreme natural milieus to microniches in the human body. Knowledge on the taxonomy, evolution, and functional diversity of NTM is updated, as well as the molecular and physiological bases for environmental adaptation, tolerance to xenobiotics, and infection biology in the human and non-human host. The complex interplay between individual, species-specific and ecological niche traits contributing to NTM resilience across ecosystems are also explored. This work hinges current understandings of NTM, approaching their biology and heterogeneity from several angles and reinforcing the complexity of these microorganisms often associated with a multiplicity of diseases, including pulmonary, soft-tissue, or milliary. In addition to emphasizing the cornerstones of knowledge involving these bacteria, we identify research gaps that need to be addressed, stressing out the need for decision-makers to recognize NTM infection as a public health issue that has to be tackled, especially when considering an increasingly susceptible elderly and immunocompromised population in developed countries, as well as in low- or middle-income countries, where NTM infections are still highly misdiagnosed and neglected.

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“…As an alternative to counting colony forming units according to growth, bacterial cells can be counted using a flow cytometer after being appropriately stained with fluorescent dyes [28]. This method resulted in the highest number of total cells counted within the same reservoir water.…”

Section: Cultivation-based Methods and Community Analysismentioning

confidence: 99%

Bacterial Respiration Used as a Proxy to Evaluate the Bacterial Load in Cooling Towers

Toman

Kiilerich

Marshall

et al. 2020

Sensors

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Evaporative cooling towers to dissipate excess process heat are essential installations in a variety of industries. The constantly moist environment enables substantial microbial growth, causing both operative challenges (e.g., biocorrosion) as well as health risks due to the potential aerosolization of pathogens. Currently, bacterial levels are monitored using rather slow and infrequent sampling and cultivation approaches. In this study, we describe the use of metabolic activity, namely oxygen respiration, as an alternative measure of bacterial load within cooling tower waters. This method is based on optical oxygen sensors that enable an accurate measurement of oxygen consumption within a closed volume. We show that oxygen consumption correlates with currently used cultivation-based methods (R2 = 0.9648). The limit of detection (LOD) for respiration-based bacterial quantification was found to be equal to 1.16 × 104 colony forming units (CFU)/mL. Contrary to the cultivation method, this approach enables faster assessment of the bacterial load with a measurement time of just 30 min compared to 48 h needed for cultivation-based measurements. Furthermore, this approach has the potential to be integrated and automated. Therefore, this method could contribute to more robust and reliable monitoring of bacterial contamination within cooling towers and subsequently increase operational stability and reduce health risks.

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Bacterial community dynamics and disinfection impact in cooling water systems

Cited by 38 publications

References 45 publications

Computational flow cytometry of planktonic populations for the evaluation of microbiological-control programs in district cooling plants

Computational flow cytometry of planktonic populations for the evaluation of microbiological-control programs in district cooling plants

Non-Tuberculous Mycobacteria: Molecular and Physiological Bases of Virulence and Adaptation to Ecological Niches

Bacterial Respiration Used as a Proxy to Evaluate the Bacterial Load in Cooling Towers

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