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Claveau L, Hudson N, Jeffrey P, Hassard F. To gate or not to gate: Revisiting drinking water microbial assessment through flow cytometry fingerprinting. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169138. [PMID: 38070556 DOI: 10.1016/j.scitotenv.2023.169138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/20/2023] [Accepted: 12/04/2023] [Indexed: 01/18/2024]
Abstract
Flow cytometry has been utilized for over a decade as a rapid and reproducible approach to assessing microbial quality of drinking water. However, the need for specialized expertise in gating-a fundamental strategy for distinguishing cell populations-introduces the potential for human error and obstructs the standardization of methods. This work conducts a comprehensive analysis of various gating approaches applied to flow cytometric scatter plots, using a dataset spanning a year. A sensitivity analysis is carried out to examine the impact of different gating strategies on final cell count results. The findings show that dynamic gating, which requires user intervention, is essential for the analysis of highly variable raw waters and distributed water. In contrast, static gating proved suitable for more stable water sources, interstage sample locations, and water presenting a particularly low cell count. Our conclusions suggest that cell count analysis should be supplemented with fluorescence fingerprinting to gain a more complete understanding of the variability in microbial populations within drinking water supplies. Establishing dynamic baselines for each water type in FCM monitoring studies is essential for choosing the correct gating strategy. FCM fingerprinting offers a dynamic approach to quantify treatment processes, enabling options for much better monitoring and control. This study offers new insights into the vagaries of various flow cytometry gating strategies, thereby substantially contributing to best practices in the water industry. The findings foster more efficient and reliable water analysis, improving of standardizing methods in microbial water quality assessment using FCM.
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Affiliation(s)
- L Claveau
- Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK
| | - N Hudson
- South East Water, Rocfort Road, Snodland, Kent ME6 5AH, UK
| | - P Jeffrey
- Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK
| | - F Hassard
- Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
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2
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Zhang W, Chu H, Yang L, You X, Yu Z, Zhang Y, Zhou X. Technologies for pollutant removal and resource recovery from blackwater: a review. FRONTIERS OF ENVIRONMENTAL SCIENCE & ENGINEERING 2023; 17:83. [PMID: 36776490 PMCID: PMC9898867 DOI: 10.1007/s11783-023-1683-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/24/2022] [Accepted: 12/04/2022] [Indexed: 06/18/2023]
Abstract
Blackwater (BW), consisting of feces, urine, flushing water and toilet paper, makes up an important portion of domestic wastewater. The improper disposal of BW may lead to environmental pollution and disease transmission, threatening the sustainable development of the world. Rich in nutrients and organic matter, BW could be treated for resource recovery and reuse through various approaches. Aimed at providing guidance for the future development of BW treatment and resource recovery, this paper presented a literature review of BWs produced in different countries and types of toilets, including their physiochemical characteristics, and current treatment and resource recovery strategies. The degradation and utilization of carbon (C), nitrogen (N) and phosphorus (P) within BW are underlined. The performance of different systems was classified and summarized. Among all the treating systems, biological and ecological systems have been long and widely applied for BW treatment, showing their universality and operability in nutrients and energy recovery, but they are either slow or ineffective in removal of some refractory pollutants. Novel processes, especially advanced oxidation processes (AOPs), are becoming increasingly extensively studied in BW treatment because of their high efficiency, especially for the removal of micropollutants and pathogens. This review could serve as an instructive guidance for the design and optimization of BW treatment technologies, aiming to help in the fulfilment of sustainable human excreta management.
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Affiliation(s)
- Wei Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
| | - Huaqiang Chu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
| | - Libin Yang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
| | - Xiaogang You
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
| | - Zhenjiang Yu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
| | - Yalei Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
| | - Xuefei Zhou
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092 China
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Scott LC, Aubee A, Wilson MJ, Esser S, Descamps D, Lee N, Distler E, Aw TG. Leave No Trace? Ecological and anthropogenic determinants of antibiotic resistant bacteria in a recreational alpine environment. ENVIRONMENTAL RESEARCH 2023; 216:114617. [PMID: 36273598 DOI: 10.1016/j.envres.2022.114617] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 10/05/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Antibiotic resistant bacteria (ARB) have been detected in remote environments, but the degree to which their presence is due to anthropogenic contamination remains unclear. Here, anthropogenic and ecological determinants of ARB were characterized in remote and highly visited areas of Rocky Mountain National Park in the United States. Soil and water samples were collected from 29 sites once a month for three months and measured for bacteria resistant to seven antibiotics with flow cytometry. A novel index of the likelihood of human presence (HPI) was generated for estimating human impact on ARB abundance. The HPI accounted for 44% of variation in ARB abundance in water samples (p < 0.0001) and 51% of variation in soil samples (p < 0.00001). Human presence index was illustrated as a reliable predictor of ARB abundance despite a tendency to underpredict at higher levels of human impact. Ecological determinants such as temperature, elevation, slope, and aspect were also found to be significantly associated with ARB abundance. These findings suggest that human presence drives the abundance of ARB in Rocky Mountain National Park, but ecological variables play a significant role in their presence and dispersal.
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Affiliation(s)
- Laura C Scott
- Tulane University School of Public Health and Tropical Medicine, Department of Environmental Health Sciences, New Orleans, LA, 70112, USA.
| | - Alexandra Aubee
- Tulane University School of Public Health and Tropical Medicine, Department of Environmental Health Sciences, New Orleans, LA, 70112, USA
| | - Mark J Wilson
- Tulane University School of Public Health and Tropical Medicine, Department of Environmental Health Sciences, New Orleans, LA, 70112, USA
| | - Scott Esser
- Continental Divide Research Learning Center, Rocky Mountain National Park, National Park Service, Estes Park, CO, 80517, USA
| | - Denisse Descamps
- Tulane University School of Public Health and Tropical Medicine, Department of Epidemiology, New Orleans, LA, 70112, USA
| | - Nicholas Lee
- Tulane University School of Public Health and Tropical Medicine, Department of Environmental Health Sciences, New Orleans, LA, 70112, USA
| | - Emiko Distler
- Tulane University School of Public Health and Tropical Medicine, Department of Environmental Health Sciences, New Orleans, LA, 70112, USA
| | - Tiong Gim Aw
- Tulane University School of Public Health and Tropical Medicine, Department of Environmental Health Sciences, New Orleans, LA, 70112, USA.
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Cheswick R, Nocker A, Moore G, Jefferson B, Jarvis P. Exploring the use of flow cytometry for understanding the efficacy of disinfection in chlorine contact tanks. WATER RESEARCH 2022; 217:118420. [PMID: 35468557 DOI: 10.1016/j.watres.2022.118420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
A pilot scale chlorine contact tank (CCT) with flexible baffling was installed at an operational water treatment plant (WTP), taking a direct feed from the outlet of the rapid gravity filters (RGF). For the first time, disinfection efficacy was established by direct microbial monitoring in a continuous reactor using flow cytometry (FCM). Disinfection variables of dose, time, and hydraulic efficiency (short circuiting and dispersion) were explored following characterisation of the reactor's residence time distributions (RTD) by tracer testing. FCM enabled distinction to be made between changes in disinfection reactor design where standard culture-based methods could not. The product of chlorine concentration (C) and residence time (t) correlated well with inactivation of microbes, organisms, with the highest cell reductions (N/N0) reaching <0.025 at Ctx¯ of 20 mg.min/L and above. The influence of reactor geometry on disinfection was best shown from the Ct10. This identified that the initial level of microbial inactivation was higher in unbaffled reactors for low Ct10 values, although the highest levels of inactivation of 0.015 could only be achieved in the baffled reactors, because these conditions enabled the highest Ct10 values to be achieved. Increased levels of disinfection were closely associated with increased formation of the trihalomethane disinfection by-products. The results highlight the importance of well-designed and operated CCT. The improved resolution afforded by FCM provides a tool that can dynamically quantify disinfection processes, enabling options for much better process control.
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Affiliation(s)
- Ryan Cheswick
- Cranfield University, Bedford, MK43 0AL, UK; Scottish Water, Castle House, Dunfermline, KY11 8GG, UK
| | | | - Graeme Moore
- Scottish Water, Castle House, Dunfermline, KY11 8GG, UK
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Nocker A, Lindfeld E, Wingender J, Schulte S, Dumm M, Bendinger B. Thermal and chemical disinfection of water and biofilms: only a temporary effect in regard to the autochthonous bacteria. JOURNAL OF WATER AND HEALTH 2021; 19:808-822. [PMID: 34665773 DOI: 10.2166/wh.2021.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Thermal and chemical disinfection of technical water systems not only aim at minimizing the level of undesired microorganisms, but also at preventing excessive biofouling, clogging and interference with diverse technical processes. Typically, treatment has to be repeated in certain time intervals, as the duration of the effect is limited. The transient effect of disinfection was demonstrated in this study applying different treatments to water and biofilms including heat, chlorination, a combination of hydrogen peroxide and peracetic acid and monochloramine. Despite the diverse treatments, the reduction in live bacteria was followed by regrowth in all cases, underlining the universal validity of this phenomenon. The study shows that autochthonous bacteria can reach the concentrations given prior to treatment. The reason is seen in the nutrient concentration that has not changed and that forms the basis for regrowth. Nutrients are released by disinfection from lysed cells or are still fixed in dead biomass that is subsequently scavenged by necrotrophic growth. Treatment cycles therefore only provide a transient reduction of water microbiology if nutrients are not removed. When aiming at greater sustainability of the effect, biocidal treatment has to be equally concerned about nutrient removal by subsequent cleaning procedures as about killing efficiency.
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Affiliation(s)
- Andreas Nocker
- Applied Microbiology, IWW Water Centre, Moritzstraße 26, 45476 Mülheim an der Ruhr, Germany E-mail: ;
| | - Elisa Lindfeld
- Applied Microbiology, IWW Water Centre, Moritzstraße 26, 45476 Mülheim an der Ruhr, Germany E-mail: ; ; Department of Chemical Engineering, University of Applied Sciences Münster, Stegerwaldstraße 39, 48565 Steinfurt, Germany
| | - Jost Wingender
- Applied Microbiology, IWW Water Centre, Moritzstraße 26, 45476 Mülheim an der Ruhr, Germany E-mail: ; ; Faculty of Chemistry, Environmental Microbiology and Biotechnology, Aquatic Microbiology, University of Duisburg-Essen, Universitätsstraße 5, 45141 Essen, Germany
| | - Simone Schulte
- Evonik Operations GmbH, Goldschmidtstraße 100, 45127 Essen, Germany
| | - Matthias Dumm
- thyssenkrupp Steel Europe AG, Kaiser-Wilhelm-Straße 100, 47166 Duisburg, Germany
| | - Bernd Bendinger
- Applied Microbiology, IWW Water Centre, Moritzstraße 26, 45476 Mülheim an der Ruhr, Germany E-mail: ;
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Yin Q, Nie M, Diwu Z, Zhang Y, Wang L, Yin D, Li L. Establishment and application of a novel fluorescence-based analytical method for the rapid detection of viable bacteria in different samples. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2020; 12:3933-3943. [PMID: 32724967 DOI: 10.1039/d0ay01247e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A rapid method for readily detecting the total numbers of viable bacterial cells in numerous samples (including surface water, solid inoculants, and soil samples) is reported using a newly developed hand-held fluorometer and a fluorescent dye Calcein UltraGreen™ AM. Compared to the traditional plate counting method that requires 48 hours of cultivation, the newly established method does not require any incubation time, making the detection method faster and more convenient. The portable rapid detection fluorometer has a wide dynamic range of relative fluorescence intensity from 45 to 30 133. It can detect bacterial concentration ranging from 105 to 1010 cells per mL. This newly established method has good applicability for accurately and quickly detecting the cell number of viable bacteria in various samples. The results of the fluorescence-based method were compared with those of the traditional plate counting method, and it was found that the relative standard deviation was less than 6%. This new rapid measurement system provides a robust method for the rapid on-site detection of viable bacteria.
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Affiliation(s)
- Qiuyue Yin
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, Shanxi Province, People's Republic of China.
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Vergine P, Amalfitano S, Salerno C, Berardi G, Pollice A. Reuse of ultrafiltered effluents for crop irrigation: On-site flow cytometry unveiled microbial removal patterns across a full-scale tertiary treatment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 718:137298. [PMID: 32087587 DOI: 10.1016/j.scitotenv.2020.137298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/11/2020] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
Reuse of treated wastewater for crop irrigation has been widely adopted to mitigate the effects of water scarcity on agricultural yields and to help preserving the integrity of aquatic ecosystems. This paper presents the outcomes of one-year monitoring of a full-scale agro-industrial wastewater treatment plant designed for water reuse, with a multistage tertiary treatment based on sand filtration, membrane ultrafiltration, storage and on-demand UV disinfection. We aimed to test flow cytometry as a monitoring tool to provide on-site indications on tertiary treatment performances and on the quality of treated wastewater along the treatment scheme. Membrane ultrafiltration retained prokaryotic cells and E. coli (>3 log). During storage of treated effluents, a significant decay of E. coli was observed together with the growth of prokaryotic and eukaryotic cells, and the UV disinfection was effective only against fecal indicators. The microbial quality of the treated effluent was comparable to the control groundwater locally used for irrigation. On-site rapid assessments by flow cytometry allowed unveiling crucial aspects affecting the microbiological quality of ultrafiltration permeate and treated effluent immediately after sampling, including plant operating performances and microbial removal patterns across the treatment train.
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Affiliation(s)
- Pompilio Vergine
- Water Research Institute (IRSA-CNR), Viale F. De Blasio, 5, 70132 Bari, Italy
| | - Stefano Amalfitano
- Water Research Institute (IRSA-CNR), Via Salaria Km 29.300, 00015 Monterotondo, Rome, Italy.
| | - Carlo Salerno
- Water Research Institute (IRSA-CNR), Viale F. De Blasio, 5, 70132 Bari, Italy
| | - Giovanni Berardi
- Water Research Institute (IRSA-CNR), Viale F. De Blasio, 5, 70132 Bari, Italy
| | - Alfieri Pollice
- Water Research Institute (IRSA-CNR), Viale F. De Blasio, 5, 70132 Bari, Italy
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Villarín MC, Merel S. Paradigm shifts and current challenges in wastewater management. JOURNAL OF HAZARDOUS MATERIALS 2020; 390:122139. [PMID: 32007860 DOI: 10.1016/j.jhazmat.2020.122139] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 01/10/2020] [Accepted: 01/18/2020] [Indexed: 06/10/2023]
Abstract
Wastewater is a significant environmental and public health concern which management is a constant challenge since antiquity. Wastewater research has increased exponentially over the last decades. This paper provides a global overview of the exponentially increasing wastewater research in order to identify current challenges and paradigm shifts. Besides households, hospitals and typical industries, other sources of wastewater appear due to emerging activities like hydraulic fracturing. While the composition of wastewater needs constant reassessment to identify contaminants of interest, the comprehensive chemical and toxicological analysis remains one of the main challenges in wastewater research. Moreover, recent changes in the public perception of wastewater has led to several paradigm shifts: i) water reuse considering wastewater as a water resource rather than a hazardous waste, ii) wastewater-based epidemiology considering wastewater as a source of information regarding the overall health of a population through the analysis of specific biomarkers, iii) circular economy through the implementation of treatment processes aiming at harvesting valuable components such as precious metals or producing valuable goods such as biofuel. However, wastewater research should also address social challenges such as the public acceptance of water reuse or the access to basic sanitation that is not available for nearly a third of the world population.
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Affiliation(s)
- María C Villarín
- Department of Human Geography, University of Seville, c/ Doña María de Padilla s/n, 41004, Sevilla, Spain.
| | - Sylvain Merel
- Institute of Marine Research (IMR), PO Box 1870 Nordnes, N-5817, Bergen, Norway; INRAE, UR RiverLy, 5 rue de la Doua, F-69625 Villeurbanne, France.
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Fujioka T, Boivin S. Dialysis as a new pre-treatment technique for online bacterial counting. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 714:136768. [PMID: 31982761 DOI: 10.1016/j.scitotenv.2020.136768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/24/2019] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
Real-time bacteriological counting technology is capable of providing an online profile of bacterial removal during the wastewater treatment process, and can enhance the safety of recycled water for potable water reuse. However, autofluorescence emanating from dissolved organic compounds present in treated wastewater interferes with the analysis. In this study, a novel approach is adopted, viz., dialysis treatment for the removal of dissolved interfering substances from treated wastewater, and the efficiency of this treatment protocol is evaluated as a pre-treatment technique for real-time bacteriological counting. Dialysis using membranes having a molecular weight cut-off (MWCO) of 1000 kDa and 6-8 kDa were found to successfully reduce the intensity of autofluorescence emitted from the interfering substances; whereas the courser dialysis membrane having a MWCO of 1000 kDa was found to be more effective in removing the interfering substances. Here we demonstrate for the first time that continuous online dialysis treatment aids in the direct determination of the bacterial counts in ultrafiltration- and membrane bioreactor-treated wastewaters. The results of the study indicate that the dialysis pre-treatment technique is effective for continuously reducing the concentration of interfering substances in treated wastewater, and thus allows for direct online counting of bacteria.
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Affiliation(s)
- Takahiro Fujioka
- Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
| | - Sandrine Boivin
- Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
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Fujioka T, Makabe R, Mori N, Snyder SA, Leddy M. Assessment of online bacterial particle counts for monitoring the performance of reverse osmosis membrane process in potable reuse. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 667:540-544. [PMID: 30833252 DOI: 10.1016/j.scitotenv.2019.02.339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 02/15/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
Safety of potable reuse can be enhanced by improved water quality monitoring techniques for assessing water treatment processes. This study evaluated the efficacy of online bacterial counting for continuous monitoring of reverse osmosis (RO) membranes to remove bacteria using real-time bacteriological commercial counters and an on-site pilot-scale RO system. Prior to on-site assessments, the online bacterial counting was verified by comparing the measurement of fluorescent particles in water with flow cytometry. During a seven day pilot test of RO treatment at a water reclamation plant, online bacterial counts in RO permeate were monitored below 15 counts/mL; whereas the bacterial counts in RO feed water were approximately 2500 to 10,000 counts/mL. Removal rates of bacterial counts ranged from 2.6 to 3.1-log (average = 2.9-log) by continuously monitoring bacterial removal. This is greater than a 2-log reduction frequently determined using other water quality surrogates (i.e., electrical conductivity). Overall, the continuous monitoring of bacteria in RO feed and permeate can be implemented without the addition of chemicals to provide near real-time bacterial counts to measure their reduction after RO treatment. This can be developed for continuous performance monitoring of the RO process, providing greater assurance of microbial water quality after RO treatment.
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Affiliation(s)
- Takahiro Fujioka
- Water and Environmental Engineering, Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
| | - Ryo Makabe
- R&D Division, Kyowakiden Industry Co., Ltd., 10-2 Kawaguchi-machi, Nagasaki 852-8108, Japan
| | - Naomichi Mori
- Water Reuse Promotion Center, 4-5 Nihonbashiyokoyamachō, Chuo, Tokyo 103-0003, Japan
| | - Shane A Snyder
- Nanyang Environment & Water Research Institute (NEWRI), Nanyang Technological University (NTU), 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Harshbarger 108, Tucson, AZ 85721-0011, USA
| | - Menu Leddy
- Orange County Water District, 18700 Ward Street, Fountain Valley, CA 92708, USA; Essential Environmental Engineering Solutions, Huntington Beach, CA 92649, USA
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