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The occurrence and the fate of 18 ozonation by-products (OBPs) (17 different aldehydes and bromate) were studied over one year in two Canadian drinking water systems. This is the first and only study reporting the occurrence of all these non-halogenated aldehydes (NON-HALs) and haloacetaldehydes (HALs) simultaneously, based on the multi-point monitoring of water in full-scale conditions from source to distribution network. In general, the application of both post-ozonation and liquid chlorine contributed to the formation of OBPs (aldehydes and bromate). NON-HALs were present in higher concentrations than HALs. Formaldehyde, acetaldehyde, glyoxal and methylglyoxal were the most common forms of NON-HALs in the two water systems that were studied. Chloral hydrate (CH), the hydrated form of trichloroacetaldehyde, was the most dominant HAL observed. The nature of the organic matter and the water temperature proved to be important parameters for explaining the variability of aldehydes. Summer and autumn (warm seasons) were more favorable for the formation of chloral hydrate and bromate. The highest concentrations of NON-HALs were observed in spring., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This paper presents the development of a hybrid bi-level programming approach for supporting multi-stage groundwater remediation design. To investigate remediation performances, a subsurface model was employed to simulate contaminant transport. A mixed-integer nonlinear optimization model was formulated in order to evaluate different remediation strategies. Multivariate relationships based on a filtered stepwise clustering analysis were developed to facilitate the incorporation of a simulation model within a nonlinear optimization framework. By using the developed statistical relationships, predictions needed for calculating the objective function value can be quickly obtained during the search process. The main advantage of the developed approach is that the remediation strategy can be adjusted from stage to stage, which makes the optimization more realistic. The proposed approach was examined through its application to a real-world aquifer remediation case in western Canada. The optimization results based on this application can help the decision makers to comprehensively evaluate remediation performance.

The presence of off-flavour compounds such as geosmin, often found in raw water, significantly reduces the organoleptic quality of distributed water and diverts the consumer from its use. To adapt water treatment processes to eliminate these compounds, it is necessary to be able to identify them quickly. Routine analysis could be considered a solution, but it is expensive and delays associated with obtaining the results of analysis are often important, thereby constituting a serious disadvantage. The development of decision-making tools such as predictive models seems to be an economic and feasible solution to counterbalance the limitations of analytical methods. Among these tools, multi-linear regression and principal component regression are easy to implement. However, due to certain disadvantages inherent in these methods (multicollinearity or non-linearity of the processes), the use of emergent models involving artificial neurons networks such as multi-layer perceptron could prove to be an interesting alternative. In a previous paper (Parinet et al., Water Res 44: 5847-5856, ), the possible parameters that affect the variability of taste and odour compounds were investigated using principal component analysis. In the present study, we expand the research by comparing the performance of three tools using different modelling scenarios (multi-linear regression, principal component regression and multi-layer perceptron) to model geosmin in drinking water sources using 38 microbiological and physicochemical parameters. Three very different sources of water, in terms of quality, were selected for the study. These sources supply drinking water to the Québec City area (Canada) and its vicinity, and were monitored three times per month over a 1-year period. Seven different modelling methods were tested for predicting geosmin in these sources. The comparison of the seven different models showed that simple models based on multi-linear regression provide sufficient predictive capacity with performance levels comparable to those obtained with artificial neural networks. The multi-linear regression model ( R = 0.657, <0.001) used only four variables ( phaeophytin, sum of green algae, chlorophyll-a and potential Redox) in comparison with ten variables (potassium, heterotrophic bacteria, organic nitrogen, total nitrogen, phaeophytin, total organic carbon, sum of green algae, potential Redox, UV absorbance at 254 nm and atypical bacteria) for the best model obtained with artificial neural networks ( R = 0.843). [ABSTRACT FROM AUTHOR]

Potable water treatment is one of the most challenging and complex systems that municipalities need to deal with considering limited resources. A study from mid-90s showed that the continuously deteriorating Canadian water supply system would require $3.1 billion to bring the system at satisfactory level. Drinking water treatment plants (WTP) include several components, such as tanks, basin, and pumps. Operators are able to spend a small portion of the available resources or their plant’s infrastructure and equipment compared to water quality and day-to-day operational activities. The research presented in this technical paper aims at developing condition assessment model(s) for the WTP components. Essential condition parameters of WTP include technical, physical, environmental, and operational aspects. To determine the condition index of a WTP component, value additive multi-attribute theory has been used where average weights and scores are considered for the model parameters. Data on WTP conditions are collected from experts and consultants across Canada and the United States. It is concluded from the model results that the average condition index for settling basins, ranges from 9.6 (best scenarios) to 1.9 (worst scenarios) and from 9.6 to 3.4 for pumps. Analysis reveals that, for tank and basins, design and construction parameter is the most important parameter for WTP condition, while the operational parameter is the most important one for pumps. The developed models are expected to benefit academics and practitioners (municipal engineers, consultants, and contractors) to prioritize inspection and rehabilitation planning for existing water treatment plants. [ABSTRACT FROM AUTHOR]

A growing body of evidence indicates that extraintestinal pathogenic E. coli (ExPEC) readily survive wastewater treatment, raising concerns about the public health risks associated with exposure to wastewater-contaminated environments. In this study, E. coli isolates recovered from chlorinated sewage or treated wastewater effluents in Canada were screened for ExPEC virulence markers. Eighty-six isolates were identified as presumptive ExPEC, clustering within major pandemic lineages including ST131, ST95, and ST73 according to multilocus sequence typing analyses. Across the whole, core, and accessory genome, 37 isolates were extremely similar to clinical bloodborne E. coli (BBEC) and neonatal meningitic E. coli (NMEC) strains, suggesting that these wastewater isolates may exhibit a similar phenotypically related pathogenic potential. Interestingly, ExPEC strains also shared accessory gene content with naturalized wastewater strains, suggesting a common genetic capacity for surviving water treatment. Collectively, these findings suggest that E. coli strains that may cause septicemia and meningitis are surviving wastewater treatment and may be transmissible through wastewater effluents. [ABSTRACT FROM AUTHOR]

Global ballast water management aims to reduce the transport and introduction of non-indigenous species through practices such as ballast water exchange and ballast water treatment. Comprehensive enforcement to ensure vessels are meeting ballast water management requirements are a key part of success, but such activities are limited by available resources. Targeted and/or stratified enforcement activities are one option to make best use of available resources. International vessels are required to submit ballast water reporting forms prior to arrival at many ports around the world, declaring quantities, geographic sources, management undertaken and expected discharge location. These data are essential for risk assessment and trends analysis, but the inflow of data can be overwhelming for daily operations, particularly for jurisdictions with many ports and/or high vessel traffic. Having near real-time access to ballast water data enhances opportunities for data validation and verification and facilitates customized reports such as mapping of exchange coordinates and ballast water discharge statistics. Customized software enables seamless application of best-available science through integration of decision-support tools. The Ballast Water Information System (BWIS) was developed to support daily ballast water enforcement activities and scientific research in Canada. The BWIS increases accessibility of ballast water report data and streamlines data processing to support decision-making using an on-line platform. [ABSTRACT FROM AUTHOR]

All of the pollutants found in stormwater runoff at airports, including surface and aircraft de-icing/anti-icing glycols, can be treated and removed to low levels in well-designed sub-surface flow (SSF) constructed wetland systems. There are two common forms of constructed wetlands used for pollution control: those where water flows over the surface among wetland plants (free water surface or marsh type wetlands); and SSF types where the wastewater flows below the normally dry surface of a gravel substrate in which the wetland plants grow. SSF wetlands have no open water to attract waterfowl and are particularly suitable for use at airports. Of the glycol used at Edmonton International Airport (EIA), 80 to 90% eventually entered surface runoff. Edmonton International Airport's operator, the Edmonton Regional Airports Authority (Edmonton Airports) evaluated a number of glycol management options, including constructed wetlands. As a result, a very large SSF wetland system was installed to handle glycol-contaminated stormwater. This paper reviews results of a feasibility study carried out to define design parameters and scale up kinetics for this wetland system, the detailed design that resulted, the SSF wetland's construction, and the start-up of the Edmonton facilities in August of 2000. It also compares the Edmonton wetland system with a similar facility at Heathrow Airport in the United Kingdom. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This analysis employs a stochastic cost frontier to estimate relationships between source water quality, production costs, and cost efficiency in Canadian municipal water treatment facilities. Data for the analysis are obtained primarily from a census of water providers that contains detailed information on operational costs, source water quality, and treatment technologies. Results show water quality, as measured by turbidity, is a significant determinant of production costs. The estimated elasticity for turbidity is 0.1, with a 95% confidence interval of 0.06 to 0.14. We find no significant differences in cost efficiency across regions, treatment technologies, output, or turbidity levels. [ABSTRACT FROM AUTHOR]

Urban freshwaters provide a range of ecosystem services, including stormwater management, water treatment, biodiversity, and aesthetics. Management of freshwaters should aim to maximise as many of these services as possible, but managers are often focused on individual services. To test for the biodiversity value of stormwater management ponds (SMPs) in Ottawa, Canada, 20 SMPs were surveyed for macroinvertebrates using standardised sampling techniques. These were compared against 10 wetlands that were not managed for stormwater control (a combination of ornamental lakes, natural lakes, and nature reserves) in and around the same urban area (a total of 30 ponds). Natural wetlands and SMPs were very different in their water chemistry, which was correlated with the proportion of urban land use within 1 km of the site, with higher conductivity in SMPs with increasing urban land cover ( P = 0.046). Despite this, natural wetlands and the richest SMPs contained similar levels of biodiversity and similar macroinvertebrate community structure. This study highlights that stormwater management can occur alongside biodiversity enhancement in urban areas, but correlations between urban land use, water chemistry, and the structure of biological communities suggests that run-off from urban areas is likely a major factor in structuring biological communities in built-up regions. [ABSTRACT FROM AUTHOR]

Background: The discharge of complex mixtures of nutrients, organic micropollutants, and antibiotic resistance genes from treated municipal wastewater into freshwater systems are global concerns for human health and aquatic organisms. Antibiotic resistance genes (ARGs) are genes that have the ability to impart resistance to antibiotics and reduce the efficacy of antibiotics in the systems in which they are found. In the rural community of Grand Marais, Manitoba, Canada, wastewater is treated passively in a sewage lagoon prior to passage through a treatment wetland and subsequent release into surface waters. Using this facility as a model system for the Canadian Prairies, the two aims of this study were to assess: (a) the presence of nutrients, micropollutants (i.e., pesticides, pharmaceuticals), and ARGs in lagoon outputs, and (b) their potential removal by the treatment wetland prior to release to surface waters in 2012. Results: As expected, concentrations of nitrogen and phosphorus species were greatest in the lagoon and declined with movement through the wetland treatment system. Pharmaceutical and agricultural chemicals were detected at concentrations in the ng/L range. Concentrations of these compounds spiked downstream of the lagoon following discharge and attenuation was observed as the effluent migrated through the wetland system. Hazard quotients calculated for micropollutants of interest indicated minimal toxicological risk to aquatic biota, and results suggest that the wetland attenuated atrazine and carbamazepine significantly. There was no significant targeted removal of ARGs in the wetland and our data suggest that the bacterial population in this system may have genes imparting antibiotic resistance. Conclusions: The results of this study indicate that while the treatment wetland may effectively attenuate excess nutrients and remove some micropollutants and bacteria, it does not specifically target ARGs for removal. Additional studies would be beneficial to determine whether upgrades to extend retention time or alter plant community structure within the wetland would optimize removal of micropollutants and ARGs to fully characterize the utility of these systems on the Canadian Prairies. [ABSTRACT FROM AUTHOR]

Canada’s oil sands industry uses large volumes of freshwater to extract bitumen from surface-mined ore. With oil production expected to increase 3-fold over the next decade, process water treatment has become a critical issue for oil sands operators, both in terms of sustaining bitumen recovery and protecting freshwater resources. To identify candidate treatment technologies, a review was conducted on the state-of-the-art of water treatment in the oil industry. Significant developments include (i) chemical modifications to adsorbents and membranes to improve pollutant removal and reduce fouling; (ii) hybridization of adsorbent, membrane, and bioreactor technologies to enhance the biological treatment of toxic feedwaters; (iii) advances in photocatalytic oxidation of organic compounds; and (iv) implementation of large-scale treatment wetlands to treat hydrocarbon-contaminated wastewaters. In adapting treatment technologies to the oil sands, operators will need to consider the fouling potential of bitumen and fine clays, the effect of process water alkalinity on treatment performance, and the biodegradability of toxic organic compounds. L'industrie des sables bitumineux au Canada utilise d'importants volumes d'eau douce afin d'extraire le bitume du minerai prélevé en surface. En considérant que la production de pétrole devrait tripler au cours de la prochaine décennie, le traitement de l'eau de procédé devient une préoccupation cruciale pour les exploitants des sables bitumineux en termes de récupération durable du pétrole et de la protection des ressources en eau douce. Afin d'identifier des technologies de traitement potentielles, un examen de l'état des connaissances sur le traitement des eaux a été réalisé pour l'industrie du pétrole. Les développements importants comprennent : (i) des modifications chimiques aux adsorbants et aux membranes afin d'améliorer l'élimination des polluants et réduire le colmatage; (ii) l'hybridation de l'adsorbant, la membrane et les technologies des bioréacteurs afin d'améliorer le traitement biologique des eaux d'entrée toxiques; (iii) des progrès dans l'oxydation photocatalytique des composés organiques; et (iv) l'implantation de marécages de traitement à grande échelle afin de traiter les eaux usées contaminées par les hydrocarbures. En adoptant ces technologies de traitement aux sables bitumineux, les exploitants devront tenir compte du potentiel de colmatage du bitume et des argiles fines, de l'effet de l'alcalinité de l'eau de procédé sur le rendement du traitement, ainsi que de la biodégradabilité des composés organiques toxiques. [ABSTRACT FROM AUTHOR]