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6. List of contributors

Author

Beauchamp, Nicolas, primary, Bouchard, Christian, additional, Brogat, Marine, additional, Burgess, Christopher, additional, Causse, Jean, additional, Delpla, Ianis, additional, Dorea, Caetano, additional, Junqua, Guillaume, additional, Rodriguez, Manuel, additional, Roig, Benoit, additional, Thomas, Marie-Florence, additional, and Thomas, Olivier, additional

Published
2022
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8. Water and food insecurity and linkages with physical and sexual intimate partner violence among urban refugee youth in Kampala, Uganda: cross-sectional survey findings

Author

Logie, Carmen H., primary, Okumu, Moses, additional, Tailor, Lauren, additional, Taing, Lina, additional, Dorea, Caetano, additional, Mbuagbaw, Lawrence, additional, Hakiza, Robert, additional, Kibuuka-Musoke, Daniel, additional, Katisi, Brenda, additional, Nakitende, Aidah, additional, Kyambadde, Peter, additional, MacKenzie, Frannie, additional, and Admassu, Zerihun, additional

Published
2024
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14. Chemically-enhanced gravel pre-filtration for slow sand filtration

Author

Dorea, Caetano Chang

Subjects
628.164
Abstract

The simple operational and maintenance requirements of slow sand filtration (SSF), coupled with its high biological treatment efficiency makes it an attractive technology. The main limitation of SSF is its vulnerability to high suspended solids loadings. Pre-treatment in such instances can be achieved by gravel filtration. Cases of gravel pre-filtration underperformance have been attributed to significant fractions of influent suspended particles in the colloidal range. Maximum limits of turbidity for the application of gravel pre-filters have also been suggested. A simple intervention to overcome such water quality constraints can be through the dosing of a coagulant (aluminium sulfate) upstream of the pre-filtration stage; enhancing the pre-treatment efficiency, in what could be defined as direct (gravel) filtration. Previous studies have investigated its use as a pre-treatment for SSF; however, the results emphasise pre-filtration treatment efficiency and do not consider the effectiveness of the pre-treatment in protecting the slow sand filters. Also, because of the potential toxic effects of A1 residuals, its upstream use in relation to a biological SSF treatment has never been properly evaluated. The objectives of this study were: assess the efficiency as well as the effectiveness of chemically- enhanced up-flow gravel filters in series (UGFS) as pre-treatment for SSF and study the impact of aluminium residuals on the treatment performance and potential effects on biological activity. Preliminary experiments and first set of runs with chemically-enhanced pre-filter showed evidence of wall-effects due to the media size/column diameter ratio. This experimental design shortcoming was thought not to have affected the overall trends of results and was addressed for the set of pilot-experiments on which most conclusions are based. The results from the experimental work have shown that chemically-enhanced gravel pre-filtration can be effective only if coagulant dose is carefully controlled. Contrary to previous research, it was found that when resorting to chemically-enhanced pre-treatment (with alum) turbidities of less than 2 NTU (nephelometric turbidity units) should be targeted for in order to ensure an efficient and effective SSF pre-treatment. Such control will minimise A1 residuals that can otherwise cause a premature blockage of the slow sand filter by A1 hydroxide precipitates even with influent turbidities below 10 NTU. This was speculated to occur possibly due to size and mechanical properties of deposits retained on the uppermost layers of the SSF beds. A1 speciation analyses revealed that A1 residuals from chemically-enhanced pre-filtration were found to be mostly of inorganically- bound Al. This fraction consisted mainly of A1 in its form which is considered to be potentially more bioavailable (and possibly toxic) to aquatic (micro)organisms. However, slow sand filtration column trials found that filters dosed with the potentially more labile form of A1 did not show any significant difference in terms of treatment performance parameters and biological activity indicators. It has been demonstrated that chemically-enhanced pre-filtration (with alum) may not be an effective pre-treatment on the basis that it may cause an early blockage of the slow sand filters. There was no evidence of effect of A1 on biological treatment of the slow sand filtration process.

Published
2005

17. Water insecurity and sexual and gender-based violence among refugee youth: qualitative insights from a humanitarian setting in Uganda

Author

Logie, Carmen H., primary, Okumu, Moses, additional, Coelho, Madelaine, additional, Loutet, Miranda G., additional, Narasimhan, Manjulaa, additional, Lukone, Simon Odong, additional, Kisubi, Nelson, additional, Musoke, Daniel Kibuuka, additional, Kyambadde, Peter, additional, Dorea, Caetano, additional, and Taing, Lina, additional

Published
2022
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18. Testing specificity and sensitivity of wastewater-based epidemiology for detecting SARS-CoV-2 in four communities on Vancouver Island, Canada

Author

Masri, Nadia Zeina, primary, Card, Kiffer George, additional, Caws, Emmanuelle A., additional, Babcock, Alana, additional, Powell, Ryan, additional, Lowe, Christopher J., additional, Donovan, Shelley, additional, Norum, Shelley, additional, Lyons, Shirley, additional, De Pol, Sean, additional, Kostenchuk, Lareina, additional, Dorea, Caetano, additional, Lachowsky, Nathan J., additional, Willerth, Stephanie M., additional, Fyles, Thomas M., additional, and Buckley, Heather L., additional

Published
2022
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19. Real-Time Estimation of Disinfection By-Products through Differential UV Absorbance

Author

Guilherme Stéphanie and Dorea Caetano

Subjects
differential UV absorbance, disinfection by-products, drinking water monitoring, Hydraulic engineering, TC1-978, Water supply for domestic and industrial purposes, TD201-500
Abstract

Efforts to control of unwanted disinfection by-products (DBPs) can be hindered by the relatively low-frequency data that is generated from DBP monitoring for regulatory purposes. Differential UV absorbance (DUVA) has the potential to overcome some of these difficulties as a relatively simple and low-cost technique for the estimation of regulated DBPs (i.e., trihalomethanes, THMs, and haloacetic acids, HAAs). DUVA is based on the principle that differences in UV absorbance at specific wavelengths before and after chlorination can be correlated to DBP occurrence. This project sought to assess a lab-based protocol for the determination of a site-specific linear calibration curve for in situ real-time estimations of DBPs from DUVA measurement in water treatment plants (WTPs). A field spectrophotometer probe capable of high frequency scans within the UV light wavelength spectra with light paths of 100 mm was used. Models were developed to estimate DBP levels, at a scale representative of DUVA and DBP levels that actually occur in the WTP under study. Results showed that level of uncertainty on DBP levels estimation is relatively low (23% for HAAs and 32% for THMs). Although DBP estimations through DUVA are not of regulatory value, they can be used for real-time estimation of DBP levels to better inform operational decision making in water treatment plants and management of DBPs in distribution systems.

Published
2020
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22. Drinking water quality assessment and management [chapter 10]

Author

Beauchamp, Nicolas, Delpla, Ianis, Dorea, Caetano, Bouchard, Christian, Thomas, Marie-Florence, Thomas, Olivier, Rodriguez, Manuel, Laval University, Quebec, Canada, University of Victoria [Canada] (UVIC), École des Hautes Études en Santé Publique [EHESP] (EHESP), Département des sciences en santé environnementale (DEESSE), Institut de recherche en santé, environnement et travail (Irset), Université d'Angers (UA)-Université de Rennes (UR)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), and Laboratoire d'étude et de recherche en environnement et santé (LERES)

Subjects
disinfection by-products, THM, Drinking water production, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], online monitoring, quality of resources, [SDE]Environmental Sciences, rainfalls impact, early warning systems, [SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie, SUVA
Abstract

International audience; The assessment of drinking water quality is one of the main applications of UV–visible spectrophotometry. From the quality of resources to tap water, UV sensing is used for the characterization of water resources (freshwater or groundwater) and drinking water even during rainfalls or floods, for water treatment assistance or as early warning system in the case of accidental or intentional contamination. On the other hand, UV measurement is more and more considered as a surrogate parameter for the monitoring or the prediction of disinfection by-products. Finally, UV spectrophotometry remains a good tool for the chemical characterization of drinking water either in the distribution system or packed in bottles.

Published
2022

31. Precipitation as the main mechanism for Cd(II), Pb(II) and Zn(II) removal from aqueous solutions using natural and activated forms of red mud

Author

da Conceição, Fabiano Tomazini, primary, da Silva, Mariana Scicia Gabriel, additional, Menegário, Amauri Antonio, additional, Antunes, Maria Lucia Pereira, additional, Navarro, Guillermo Rafael Beltran, additional, Fernandes, Alexandre Martins, additional, Dorea, Caetano, additional, and Moruzzi, Rodrigo Braga, additional

Published
2021
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32. sj-pdf-1-ehi-10.1177_11786302211014400 – Supplemental material for Assessment of Decontamination and Reuse of Disposable Filter Funnels Used in Microbiological Water Quality Tests

Author

Zimmer, Camille, Cassivi, Alexandra, Baía, Celia C, Tilley, Elizabeth, Bain, Robert, Johnston, Richard, and Dorea, Caetano C

Subjects
111799 Public Health and Health Services not elsewhere classified, FOS: Health sciences
Abstract

Supplemental material, sj-pdf-1-ehi-10.1177_11786302211014400 for Assessment of Decontamination and Reuse of Disposable Filter Funnels Used in Microbiological Water Quality Tests by Camille Zimmer, Alexandra Cassivi, Celia C Baía, Elizabeth Tilley, Robert Bain, Richard Johnston and Caetano C Dorea in Environmental Health Insights

Published
2021
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33. Evaluation and application of chlorine decay models for humanitarian emergency water supply contexts.

Author

Wu, Hongjian and Dorea, Caetano C.

Subjects
WATER chlorination, WATER disinfection, WATER supply, CHLORINE, STANDARD deviations
Abstract

Chlorine is a widely used water disinfectant in humanitarian emergency water supply. However, its effective application can be limited by the uncertainty in initial dose determination. The target free chlorine residual in water should achieve both health objectives and aesthetic considerations, but the varying field conditions and changing source water quality may affect the performance of chlorination strategies. A chlorine dose predictive tool could assist in initial dose determination. To this end, an accurate chlorine decay kinetic model can serve as a strong foundation for developing such a tool. In this study, a literature search identified 7 basic chlorine decay kinetic models that were subsequently tested with 610 different chlorine decay test data (from a semi-systematic literature search and laboratory-generated results). The models were then ranked based on their goodness of fit (R2) and root mean square error. An empirical model, power models and parallel models were found able to fit most decay data with more than half of the regressions resulting in R2 value over 0.97. First order models can achieve R2 value above 0.95 when the data points in the rapid phase are excluded from the model fitting. The power models and parallel models can form a strong basis for developing a chlorine dose predictive tool if the power term and the ratio term (model parameters) can be controlled. An essential next step is to evaluate the relationships between easily obtainable water parameters in the field and the decay term in the models to allow rapid model calibration. [ABSTRACT FROM AUTHOR]

Published
2022
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40. Real-Time Estimation of Disinfection By-Products through Differential UV Absorbance

Author

Dorea Caetano and Guilherme Stéphanie

Subjects
differential UV absorbance, lcsh:TD201-500, lcsh:Hydraulic engineering, business.industry, disinfection by-products, Science and engineering, Geography, Planning and Development, Uv absorbance, Aquatic Science, Biochemistry, lcsh:Water supply for domestic and industrial purposes, drinking water monitoring, lcsh:TC1-978, Research council, Time estimation, Process engineering, business, Differential (mathematics), Water Science and Technology, Mathematics
Abstract

Efforts to control of unwanted disinfection by-products (DBPs) can be hindered by the relatively low-frequency data that is generated from DBP monitoring for regulatory purposes. Differential UV absorbance (DUVA) has the potential to overcome some of these difficulties as a relatively simple and low-cost technique for the estimation of regulated DBPs (i.e., trihalomethanes, THMs, and haloacetic acids, HAAs). DUVA is based on the principle that differences in UV absorbance at specific wavelengths before and after chlorination can be correlated to DBP occurrence. This project sought to assess a lab-based protocol for the determination of a site-specific linear calibration curve for in situ real-time estimations of DBPs from DUVA measurement in water treatment plants (WTPs). A field spectrophotometer probe capable of high frequency scans within the UV light wavelength spectra with light paths of 100 mm was used. Models were developed to estimate DBP levels, at a scale representative of DUVA and DBP levels that actually occur in the WTP under study. Results showed that level of uncertainty on DBP levels estimation is relatively low (23% for HAAs and 32% for THMs). Although DBP estimations through DUVA are not of regulatory value, they can be used for real-time estimation of DBP levels to better inform operational decision making in water treatment plants and management of DBPs in distribution systems.

Published
2020
Full Text
View/download PDF

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