Monica Emelko - Academia.edu (original) (raw)

Papers by Monica Emelko

Kyle obtained his B.A.Sc. in Civil Engineering with a Certificate in Structural Engineering at th... more Kyle obtained his B.A.Sc. in Civil Engineering with a Certificate in Structural Engineering at the University of Waterloo in 2015. He is now furthering his knowledge in the discipline of structural engineering by pursuing a research based master's (M.A.Sc.) degree co-supervised by Dr. West and Dr. Walbridge. Kyle's research focuses on understanding the fatigue behaviour of slip-critical shear connectors used in composite bridges between steel girders and precast concrete slabs. The proposed research will involve both experimental and numerical components. Scaled test specimens will be fabricated and loaded cyclically to assess the fatigue life and performance of the shear connectors and a finite element model of the specimens will be generated to evaluate the performance numerically. This research is expected substantiate the reliability of using fewer required shear connectors, rendering a more efficient design.

Proceedings of SPIE, Sep 3, 2015

Safe drinking water is essential for human health, yet over a billion people worldwide do not hav... more Safe drinking water is essential for human health, yet over a billion people worldwide do not have access to safe drinking water. Due to the presence and accumulation of biological contaminants in natural waters (e.g., pathogens and neuro-, hepato-, and cytotoxins associated with algal blooms) remain a critical challenge in the provision of safe drinking water globally. It is not financially feasible and practical to monitor and quantify water quality frequently enough to identify the potential health risk due to contamination, especially in developing countries. We propose a low-cost, small-profile multispectral (MS) system based on Digital Holographic Microscopy (DHM) and investigate methods for rapidly capturing holographic data of natural water samples. We have developed a test-bed for an MSDHM instrument to produce and capture holographic data of the sample at different wavelengths in the visible and the near Infra-red spectral region, allowing for resolution improvement in the reconstructed images. Additionally, we have developed high-speed statistical signal processing and analysis techniques to facilitate rapid reconstruction and assessment of the MS holographic data being captured by the MSDHM instrument. The proposed system is used to examine cyanobacteria as well as Cryptosporidium parvum oocysts which remain important and difficult to treat microbiological contaminants that must be addressed for the provision of safe drinking water globally.

Journal of computational vision and imaging systems, Oct 3, 2016

Due to climate change, toxic cyanobacteria and algae blooms and the associated exposure risk to h... more Due to climate change, toxic cyanobacteria and algae blooms and the associated exposure risk to humans has become a global issue. As a result, routine monitoring to evaluate cell concentrations is increasingly required to ensure safe water supplies. Current methods for cyanobacteria and algae cells enumeration are time consuming and costly-intensive due to the need for manual labor, which prevents their widespread adoption for routine water monitoring.. Automated enumeration with computer-assisted image analysis has strong potential to become a viable solution for continuous routine monitoring; however, the design of such automated systems is challenging due to: a) poor contrast between the target cells and the background, b) presence of confounding cells and abiotic particles and b) image quality variability depending on factors such as the underlying microscopy system in use and the sample condition. In this study, we introduce a novel integrated imaging-based method for automated enumeration and size distribution of Microcystis aeruginosa, a species of freshwater cyanobacteria that can originate harmful blooms. The target cells were excited using a 546nm light source and the resulting fluorescent imaging signal was acquired. A probabilistic unsupervised classification approach was taken to detect Microcystis cells from the surrounding background based on the fluorescent signal. A Gaussian mixture model was learned from the fluorescent imaging signal. The detected Microcystis cells were then enumerated and statistics regarding their size distribution automatically computed. When compared to the manual enumeration data using an hemacytometer, the developed method achieved higher accuracy using much less time and resources, without cell staining. These preliminary results demonstrate the potential of the proposed method as a powerful and robust tool for water quality monitoring and safe water quality control when used alongside gold standard methods.

Current Opinion in Biotechnology, Jun 1, 2019

Drinking water biofiltration processes have evolved over time, moving from unintentional to delib... more Drinking water biofiltration processes have evolved over time, moving from unintentional to deliberate, with careful filter media selection, nutrient and trace metal supplementation, oxidant amendment, and bioaugmentation of key microorganisms, to achieve improvements in water quality. Biofiltration is on the precipice of a revolution that aims to customize the microbial community for targeted functional outcomes. These outcomes might be to enhance or introduce target functional activity for contaminant removal, to avoid hydraulic challenges, or to shape beneficially the downstream microbial community. Moving from the foundational molecular techniques that are commonly applied to biofiltration processes, such as amplicon sequencing and quantitative, real-time polymerase chain reaction, the biofiltration revolution will be facilitated by modern biotechnological tools, including metagenomics, metatranscriptomics, and metaproteomics. The application of such tools will provide a rich knowledge base of microbial community structure/function data under various water quality and operational conditions, where this information will be utilized to select biofilter conditions that promote the enrichment and maintenance of microorganisms with the desired functions.

Journal American Water Works Association, Dec 1, 2006

Effects of media, backwash, and temperature on full-scale biological filtration Full-scale biofil... more Effects of media, backwash, and temperature on full-scale biological filtration Full-scale biofiltration experiments demonstrated that good removal of biodegradable organic matter (BOM) following ozonation could be achieved without compromising particle removal. BOM removal by granular activated carbon (GAC) filter adsorbers and dual-media filters was measured using total organic carbon (TOC) and certain BOM components (carboxylic acids). The authors investigated how filter backwashing with water, water and air scour, and water and air scour at collapse-pulsing conditions affect filter biomass, BOM removal, and particle removal. At 21-24 o C, the media type did not affect BOM removal. At 1-3 o C, GAC provided substantially better removal of oxalate and TOC than did anthracite. For both media types, cold water oxalate removals were significantly impaired, compared with those achieved in warm waters. BOM removal was more resilient than particle removal to changes in backwash protocol. Phospholipid biomass concentration was not directly related to BOM removal by filters.

Les bassins versants forestiers sont gravement menacés par les feux de forêt dans l'ouest du Cana... more Les bassins versants forestiers sont gravement menacés par les feux de forêt dans l'ouest du Canada. La majeure partie de l'eau de surface utilisée par la population de l'Alberta provient du versant est des montagnes Rocheuses, dans le sud-ouest de la province. L'augmentation récente de l'ampleur et de la gravité des incendies de forêt, conjuguée à la demande en eau, se traduisent par un besoin pressant d'évaluer les risques que présentent ces incendies pour l'eau potable traitée et distribuée en aval. Les travaux réalisés dans le cadre de ce projet permettront de mieux coordonner la gestion des terres et les activités des services publics afin d'assurer la protection et le traitement appropriés de l'eau potable en Alberta, et éventuellement dans d'autres zones sujettes aux incendies de forêt, comme la Colombie-Britannique.

Scientific Reports, Jun 13, 2018

A novel imaging-driven technique with an integrated fluorescence signature to enable automated en... more A novel imaging-driven technique with an integrated fluorescence signature to enable automated enumeration of two species of cyanobacteria and an alga of somewhat similar morphology to one of the cyanobacteria is presented to demonstrate proof-of-concept that high accuracy, imagingbased, rapid water quality analysis can be with conventional equipment available in typical water quality laboratories-this is not currently available. The results presented herein demonstrate that the developed method identifies and enumerates cyanobacterial cells at a level equivalent to or better than that achieved using standard manual microscopic enumeration techniques, but in less time, and requiring significantly fewer resources. When compared with indirect measurement methods, the proposed method provides better accuracy at both low and high cell concentrations. It extends the detection range for cell enumeration while maintaining accuracy and increasing enumeration speed. The developed method not only accurately estimates cell concentrations, but it also reliably distinguishes between cells of Anabaena flos-aquae, Microcystis aeruginosa, and Ankistrodesmus in mixed cultures by taking advantage of additional contrast between the target cell and complex background gained under fluorescent light. Thus, the proposed image-driven approach offers promise as a robust and cost-effective tool for identifying and enumerating microscopic cells based on their unique morphological features. Cyanobacteria, commonly known as blue-green algae, are a group of diverse photosynthetic bacteria that occupy a broad range of aquatic and terrestrial habitats, contributing to global biodiversity and bio-geochemical cycles 1,2. In recent decades, anthropogenic activities and climate change have contributed to increases in cyanobacteria occurrence in surface waters, often leading to excessive growth and/or potentially harmful algae blooms (HABs) 3-5. Although a complex interaction of environmental factors has been shown to contribute to these blooms, the exact triggers that determine their occurrence are still poorly understood. During bloom events, some cyanobacteria species may produce taste/odor compounds (e.g., geosmin, 2-methylisoborneol) and toxic metabolites (cyanotoxins), which can threaten human and animal health, and disrupt the balance of aquatic ecosystems 6-8. As a result, many jurisdictions have introduced specific water quality regulations to protect public health and safety 8-10. Currently, drinking water quality guidelines related to cyanobacteria are based on maximum acceptable concentrations of toxins (e.g., microcystin-LR) in treated water (e.g., 1.0 µg/L proposed in WHO, 1999) or elevated levels of cyanobacterial cells (e.g., ≥100,000 cells/ml) in water supplies 7. In practice, routine quantitative cyanotoxin monitoring in water is both expensive and challenging because it is time consuming and requires sophisticated equipment and methodologies, as well as substantial technical expertise 11. Direct microscopic enumeration of cyanobacterial cells in water offers a simpler and more cost effective alternative to these approaches; as a result, it has become common practice even though it is limited by relatively high detection limits (e.g., ~10 5 cells/ml when using a typical hemacyotmeter) and the time required for identification, confirmation, and enumeration. The World Health Organization (WHO) released guidance values for recreational exposure based on cyanobacterial cell counts and chlorophyll-a concentrations 12 ; three alert levels of severity and probability of health effects

Elsevier eBooks, 2011

Microbial contamination of groundwater by viruses, bacteria, and parasitic protozoa is a signific... more Microbial contamination of groundwater by viruses, bacteria, and parasitic protozoa is a significant human health problem when drinking water supplies are untreated or inadequately treated. The decision to treat groundwater supplies, if sufficient resources are available, often depends on the adequacy of pathogen and indicator organism attenuation in the subsurface. Microbial fate and transport processes govern attenuation in the subsurface. Hence, a thorough understanding of the mechanisms and factors affecting the fate and transport of microbial contaminants in the subsurface environment is essential for the protection of public health from waterborne disease. First, the various sources and types of microbial contaminants found in the subsurface are presented. Sources of microbial contaminants may be zoogenic (e.g., wildlife) or anthropogenic (e.g., septic systems). Second, the surrogates and indicators most commonly used to assess microbial transport and fate in groundwater are discussed. These include pathogenic and nonpathogenic bacteria, bacteriophage, and microbe-sized microspheres. Next, the key processes governing microbial fate and transport are described. Microbial transport is mainly controlled by advection, whereas the key processes governing the fate of microorganisms are retention onto aquifer solid surfaces and inactivation (or survival) of the microbes. Groundwater chemistry and moisture content are identified as two of the main physicochemical factors that influence the retention and survival of microorganisms in the subsurface. Finally, the importance of linking this fundamental science to the development of appropriate public policy and land use strategy is highlighted.

Journal American Water Works Association, Dec 1, 2005

This article consolidates and updates available information on Cryptosporidium removal by filtrat... more This article consolidates and updates available information on Cryptosporidium removal by filtration, with a focus on optimal and suboptimal filtration performance. Emphasis was placed on integrating various strategies for optimizing filtration processes with the most current information regarding pathogen removal by filtration. As this review underscores, in response to regulations such as the Interim Enhanced Surface Water Treatment Rule (IESWTR) and the Long Term 2 ESWTR, there is a need to develop methods to compare the relative effectiveness of treatment alternatives and to understand the most significant operational effects on filter performance. In many cases, filters operated at or near optimal conditions can achieve in the vicinity of 3‐log (or better) removal of Cryptosporidium. Operational conditions such as coagulant upsets and end‐of‐run (early breakthrough) filtration may significantly decrease oocyst removal by drinking water filters, even when filter effluent turbidities are low (<0.3 ntu).

Water Research, Feb 1, 2009

Maintenance of appropriate chemical pretreatment is a critical component of ensuring proper filtr... more Maintenance of appropriate chemical pretreatment is a critical component of ensuring proper filtration performance. Pilot-scale in-line filtration studies were performed to investigate the relative impacts of chitosan, alum, and FeCl 3 coagulation on the removal of Cryptosporidium parvum oocysts and oocyst-sized polystyrene microspheres by granular media filtration. Similar removals of oocysts and microspheres were achieved when optimal coagulant doses were utilized. Sub-optimal alum and FeCl 3 coagulation resulted in a deterioration filter effluent turbidity (0.2-0.3 NTU) and total particle counts (30-100 total particles !2 mm/mL) that were accompanied by reduced (by w2-3-log) median oocyst and microsphere removals by filtration. At all doses investigated, chitosan coagulation resulted in excellent turbidity and particle reductions by filtration. Nonetheless, chitosan coagulation at doses of 0.1, 0.5, and 1.0 mg/L did not result in appreciable improvements in C. parvum oocyst removal relative to complete coagulation failure (median oocyst removals were <w1-log). As well, oocyst-sized polystyrene microspheres appear to be reasonable indicators of C. parvum oocyst removal by in-line filtration preceded by alum and FeCl 3 coagulation, but not chitosan coagulation.

Water Research, Jul 1, 2003

The limited efficacy of disinfectants, other than ultraviolet irradiation and ozonation, as a bar... more The limited efficacy of disinfectants, other than ultraviolet irradiation and ozonation, as a barrier against Cryptosporidium parvum in drinking water treatment has underscored the increased importance of oocyst removal by filtration. Currently, no reliable surrogates have been identified for C. parvum removal by filtration. As a result, evaluations of the Cryptosporidium removal by treatment operations have been performed using oocysts. It has typically been assumed that chemically inactivated oocysts are suitable surrogates for viable oocysts. Measurements of electrophoretic mobility, however, have shown that chemical inactivation changes the surface charge of Cryptosporidium oocysts. The present bench-scale research indicated that formalin-inactivated oocysts are reliable surrogates for viable oocysts during both stable filter operation and periods where filtration processes are challenged, such as coagulation failure. This finding is important because of the practical difficulties associated with using viable oocysts in filtration investigations. Poor coagulation conditions severely compromised removal of viable and inactivated oocysts by dual-and tri-media filters compared to stable operating conditions and filter ripening, emphasizing the importance of optimized chemical pre-treatment (coagulation) for the successful removal of oocysts during filtration. The treatment optimization experiments also indicated that tri-media filters offered only marginally higher oocyst removals than dual-media filters.

This investigation examined the removal of Cryptosporidium and several surrogates by granular med... more This investigation examined the removal of Cryptosporidium and several surrogates by granular medium filtration. The study focused on coagulation impacts on removals. Inactivated C. parvum oocysts and non-inactivated Bacillus subtilis were seeded in two pilot plants. The pilot plant locations were chosen to represent different coagulation regimes. Under optimized coagulation conditions (filter effluent turbidity < 0.1 NTU), approximately 5 log10 removal of Crypto. was obtained in one location, and approximately 3 log10 in the other. This difference is likely related at least in part to the difference in coagulation regimes. Suboptimal coagulation produced a substantial deterioration of Crypto. removal in both locations. The trends seen for Bacillus were generally similar to those observed for Crypto.. Although turbidity may be of value for assessing coagulation impacts on Crypto. removal, particle counts may be a more sensitive parameter in this regard.

Water Research, Feb 1, 2010

Environmental Science & Technology, Apr 7, 2016

It is widely believed that media surface roughness enhances particle depositionnumerous, but inc... more It is widely believed that media surface roughness enhances particle depositionnumerous, but inconsistent, examples of this effect have been reported. Here, a new mathematical framework describing the effects of hydrodynamics and interaction forces on particle deposition on rough spherical collectors in absence of an energy barrier was developed and validated. In addition to quantifying DLVO force, the model includes improved descriptions of flow field profiles and hydrodynamic retardation functions. This work demonstrates that hydrodynamic effects can significantly alter particle deposition relative to expectations when only the DLVO force is considered. Moreover, the combined effects of hydrodynamics and interaction forces on particle deposition on rough, spherical media are not additive, but synergistic. Notably, the developed model's particle deposition predictions are in closer agreement with experimental observations than those from current models, demonstrating the importance of inclusion of roughness impacts in particle deposition description/simulation. Consideration of hydrodynamic contributions to particle deposition may help to explain discrepancies between model-based expectations and experimental outcomes and improve descriptions of particle deposition during physicochemical filtration in systems with nonsmooth collector surfaces.

Environmental Science & Technology, Jun 23, 2015

Column tests were conducted to investigate media roughness impacts on particle deposition in abse... more Column tests were conducted to investigate media roughness impacts on particle deposition in absence of an energy barrier (i.e., high ionic strength). Media/collector surface roughness consistently influenced colloid deposition in a nonlinear, nonmonotonic manner such that a critical roughness size associated with minimum particle deposition could be identified; this was confirmed using a convection-diffusion model. The results demonstrate that media surface roughness size alone is inadequate for predicting media roughness impacts on particle deposition; rather, the relative size relationship between the particles and media/collectors must also be considered. A model that quantitatively considers media surface roughness was developed that described experimental outcomes well and consistently with classic colloid filtration theory (CFT) for smooth surfaces. Dimensionless-scaling factors f roughness and f PCIF were introduced and used to develop a model describing particle deposition rate (k d) and colloid attachment efficiency (α). The model includes fitting parameters that reflect the impact of critical system characteristics such as ionic strength, loading rate, hydrophobicity. Excellent agreement was found not only between the modeled outcomes for colloid attachment efficiency (α) and experimental results from the column tests, but also with experimental outcomes reported elsewhere. The model developed herein provides a framework for describing media surface roughness impacts on colloid deposition.

Journal American Water Works Association, May 1, 2003

Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐me... more Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐media filter during optimized, end‐of‐run, and breakthrough operating conditions. Oocyst‐sized polystyrene microspheres were also evaluated as surrogates for C. parvum removal by filtration. At optimal conditions, the pilot‐scale filter consistently achieved ~5‐log removal of C. parvum and microspheres. During end‐of‐run operation when filter effluent turbidity levels were <0.1 ntu, median oocyst removals deteriorated to ~3 log. During early (0.1–0.3 ntu) and late (>0.3 ntu) breakthrough, filtration oocyst removals deteriorated to ~2.1 and ~1.4 log, respectively. Microsphere removals by filtration were similar to oocyst removals during both stable and challenged operating periods, suggesting that microspheres are useful surrogates for investigating C. parvum removal.

Forest Policy and Economics, Jul 1, 2022

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... Filter Operation Effects on Pathogen Prepared by: Peter M. Huck and Monica B. Emeiko NSERC Ch... more ... Filter Operation Effects on Pathogen Prepared by: Peter M. Huck and Monica B. Emeiko NSERC Chair in Water Treatment, Department of ... mg/L polymer present) 191 Figure 7.12 Influent turbidity and coagulant dosages for full-scale testing at MWD's FE Weymouth filtration plant ...