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Increasingly stringent water quality regulations concerning microbiological parameters govern the use of groundwater resources that are vulnerable to mixing with surface waters. These drinking water sources are at higher risk for infiltration by pathogenic microorganisms, including the oocysts of the human enteroparasite Cryptosporidium spp. Cryptosporidium can cause severe gastroenteritis in humans, and the characteristics of Cryptosporidium oocysts, including low infectious dose, high resistance to inactivation, and long survival in the environment pose a significant risk to public health if present in treated drinking water. Bacillus subtilis is widely used as a surrogate for biocolloid transport in saturated porous media, and recognized as a conservative indicator for the transport of Cryptosporidium parvum oocysts during filtration. However, no study has directly compared the transport of spores from different strains within the Bacillus subtilis species. Strain variability has the potential to impact retention in porous media based on differences in size and electrophoretic mobility. The transport behaviour of four strains of Bacillus subtilis (wild-type and laboratory type, subspecies subtilis and subspecies spizizenii; 1.9 to 2.9µm diameter) is contrasted in this research to two sizes of fluorescent polystyrene microspheres (1.1µm and 4.5µm diameter) through packed saturated crushed quartz sand. A peristaltic pump was used to introduce (bio)colloids into the duplicate column apparatus at a loading rate of 0.1m/day. (Bio)colloid removal was assessed and compared by constructing breakthrough curves of normalized concentrations and box-and-whisker diagrams of percent removal of Bacillus subtilis strains. Under unfavourable conditions minimal reduction (<0.22log10) in effluent spore concentration was observed over the column depth of 15cm. In favourable attachment conditions up to 0.69 log10 reduction was observed but the sampling schedule employed was insufficient to clearly identify a pseudo steady-state plateau. An analysis of variance was used to determine the statistical significance of spore strain, subspecies, and type. A significant difference between the four strains was observed at the lower ionic strength, with spore subspecies and type affecting spore removal in unfavourable conditions (p < 0.05). Some sensitivity to settling and laboratory storage suggests that standardized sample handling procedures are required. Differences observed here between the strains of Bacillus subtilis spores indicate that riverbank filtration performance assessments and drinking water treatment plant process demonstrations may benefit from a recommended strain for use.

The use of dissolved air flotation (DAF) for drinking water treatment has steadily grown in popularity in Atlantic Canada for the treatment of low turbidity water supplies with high levels of algae or dissolved organic matter. Runoff from high intensity rainfall events may cause a rapid increase in turbidity and dissolved organic matter in rivers and lakes used for drinking water. A technical evaluation of a DAF water treatment plant (WTP) was conducted to determine the contributing factors to clearwell turbidity increases resulting from increased raw water turbidity and colour during intense rainfall and runoff events. The effect of chemical and operational factors on treatment of a low turbidity and colour water source as well as a high turbidity and colour water source were examined, including coagulant dose, coagulation pH, polyaluminum chloride (PACl) coagulant basicity and DAF recycle rate. In response to deteriorating water quality, it was found that increased coagulant addition inadvertently caused the loss of coagulation pH control in a full-scale DAF WTP, resulting in potentially elevated dissolved aluminum residuals entering the clearwell. This would have led to excessive aluminum hydroxide precipitation in the clearwell, and resulted in turbidity increases above the acceptable limit of 0.2 NTU. Turbidity was found to be better removed, and dissolved aluminum residuals minimized, when coagulation pH was set to the pH of minimum aluminum solubility vs. a lower pH of 6.0 during bench-scale DAF testing. A higher dose of coagulant was required to produce optimal removal of turbidity and dissolved organics at the pH of minimum solubility. The difference in bench-scale DAF treatment performance was found to be minimal when comparing sulphated PACl coagulants with 50 and 70+ % basicity. Charge analysis parameters zeta potential and streaming current were found to have a strong correlation in bench-scale testing, though the relationship between the two was affected by the coagulation pH. The results suggest that utilizing streaming current for coagulant dose control at a full-scale WTP would be best accomplished by establishing a consistent relationship between raw water quality, pH and other factors with streaming current experimentally before relying streaming current targets for dose control. Equivalent or improved DAF efficacy for solid-liquid separation was found when the recycle rate was lowered from 12 to 6 % in bench-scale tests and 12 to 8% in full-scale tests. The results suggested that maintaining an optimum air:solids ratio improved treatment performance, possibly by providing adequate bubble contact opportunities while minimizing excess shearing of the sludge blanket. The most significant finding of this research was that maintaining the coagulation pH in WTPs utilizing PACl coagulants is of utmost importance during source water quality deterioration in order to optimize treatment performance as well as prevent excess dissolved and precipitated aluminum from entering a public drinking water supply.

There is little understanding of federal policies, programs and processes (PPP) that structure and influence water infrastructure construction and water service delivery in First Nations communities in Canada. That First Nations face drinking water challenges is not new; however there is an acute cause for concern as recent federal funding initiatives have made limited gains. This thesis investigates the apparent disconnect between high-level PPP and ground-level outcomes through the perspectives of Ontario First Nations technical staff. Pioneering a unique approach to policy research, the thesis bridges elements of engineering, qualitative research and decolonizing methodologies to identify challenges and provide solutions. Specifically, participant interviews indicate incompatibilities between the PPP paradigm and the First Nations technical paradigm; a lack of accommodation for First Nations diversity; and a large separation between technical symptoms and their root causes. Three graphical tools, developed from the success factors and ideal vision findings, structure proposed PPP renewal. / A qualitative research investigation within the engineering field, involving decolonizing methodologies and an engineering problem-solving approach to tool development. / NSERC; Canadian Water Network; Engineers Canada

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Nanofiltration (NF) membranes have been applied successfully for the removal of inorganic and organic pollutants, including micropollutants, from drinking water for the past two decades. However, a complete and quantitative understanding of NF removal mechanisms has yet to be achieved. Quantifying the factors governing solute transport and retention by NF is necessary in order to achieve higher treatment efficiency at a lower cost. The aim of this research was to contribute to the current state of the knowledge of the mechanisms of solute retention and transport by NF membranes. The focus was on evaluating the contribution of solute-solute interactions and solute-membrane interactions on solute removal and transport mechanisms. To the knowledge of the author, at the start of this research there was a lack of understanding of the simultaneous impacts of both interactions on the performance of NF membranes, which renders this research novel. To highlight challenges faced by modern membrane plants and identify inorganic and organic pollutants of interest, a study of water quality in Scotland was carried out. Experiments were performed in dead-end stirred cells using two commercial NF membranes, TFC-SR2 and TFC-SR3 provided by Koch, which were extensively characterized. Radiolabeled Endosulfan (ES, 10 μg/L), manganese (5-1,500 mg/L) and Humic Acids (HA, 5-250 mgC/L) were spiked in synthetic water with background electrolyte (1 mM NaHCO3 and 20 mM NaCl). Calcium (Ca, 2.5 mM) was employed in fouling experiments. The influence of the complexation of solutes with HA on solute retention by NF was for the first time quantified for the solute concentrations employed in this study. It was found that manganese retention was influenced by membrane pore size and charge (solute-membrane interactions) and solute speciation (solute-solute interactions). Complexation of manganese and HA (solute-solute interactions) occurred at alkaline conditions but did not enhance manganese retention. At high pH manganese precipitated as solid MnCO3 and these precipitates achieved high retention (99%), even without the presence of HA. ES retention by NF membrane was controlled by size exclusion (solute-membrane interactions). For the tighter TFC-SR3, whose pore size are smaller than the size of ES, ES retention increased in the presence of HA, while for the looser TFC-SR2, whose pores are bigger than ES diameter, ES retention decreased in the presence of HA. For TFC-SR3 increase of ES retention in the presence of HA was due to size exclusion (solute-membrane interactions) and formation of ES-HA complexes (solute-solute interactions). For TFC-SR2 HA-membrane interactions were dominant with respect to solute-solute interactions, increasing membrane molecular weight cut-off (MWCO) and in turn passage of ES. The influence of pressure (5-15 bar) on ES retention in the presence of HA was systematically investigated. Results showed that ES transport through TFC-SR2 and TFC-SR3 was dominated by convection. For the tighter TFC-SR3 lower permeate flux was responsible for the increase of retention with pressure, while for the looser TFC-SR2 higher permeate flux increased concentration polarisation, decreasing retention with pressure. The presence of HA lowered the permeate flux, resulting in a less pronounced variation of retention with pressure for TFC-SR2 and in constant retention for TFC-SR3. The impact of manganese scaling on the performance of NF membranes was investigated at neutral pH. The effects of inorganic precipitates on flux and solute retention by NF have been so far scarcely studied and the impact of inorganic scaling on micropollutant retention by NF is unknown. Findings from this research indicated that manganese deposits did not foul the membranes but on the contrary enhanced their flux and prevented fouling by HA and Ca. The retention of ES, manganese and HA by membranes through which manganese was previously filtered was found to decrease with respect to solute retention by virgin membranes. Manganese filtration was shown to increase membrane MWCO and hydrophilicity. It was proposed that manganese-membrane interactions caused swelling of the membrane active layer by increasing the membrane free volume. The findings of this research indicated the importance of investigating simultaneously the impacts of solute-solute interactions and solute-membrane interactions to understand and explain transport and removal mechanisms of organic and inorganic contaminants by NF.

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Good water quality is very central to a country's wellbeing. Clean water is required to ensureboth the health of the population and good ecological status of the country. It is thereforeimportant to continually conduct surveys to determine the status of the water used in, forexample, households, industries and agriculture.Elevated levels of metals, sulphate, nitrate and phosphate in drinking water can lead to poorhealth through consumption and reduced harvest when the water is used in irrigation.This report aimed at examining whether the water resources available in the vicinity of Njuliquarry in Chiradzulo, Malawi, meet the requirements of drinking and irrigation water. Thestudy found that most of the studied parameters were within the recommendations set by theMalawi Bureau of Standards (MBS) and the World Health Organization (WHO). However,conductivity in some of the water samples was higher than the recommendations. Both nitrateand iron concentrations were higher than recommended at a few locations.The study cannot conclude that the water from the water sources near the Njuli quarry containharmful levels of metals, nitrate, sulfate or phosphate.

A series of pilot and full-scale experiments were carried out at the Mannheim Water Treatment Plant in Kitchener, Ontario to examine the impact of backwash technique, filter media characteristics, and combinations thereof on single stage drinking water biological filter performance. The media characteristics investigated were effective size, uniformity coefficient, and media type (GAC and anthracite). Backwash techniques investigated were the collapsed pulse backwash, the extended terminal subfluidization wash (ETSW), and the presence of chlorine in the wash water. Single stage biological filters must serve the dual purpose of biologically mediated removal of biodegradable organic matter (BOM), as well as meeting traditional filter performance criteria such as turbidity removal with minimal head loss accumulation. Accordingly, dissolved organic carbon removal, biodegradable dissolved organic carbon removal, biological respiration potential, turbidity removal, filter ripening time, and head loss accumulation were all quantified as measures of biological filtration performance. The results of this study have several implications for optimized design and operation of biological filters during drinking water treatment. An increase in effective size of media grains from 1.0 mm to 1.3 mm was shown to significantly extend filter run time by minimizing head loss accumulation without compromising turbidity or BOM removal. Uniformity coefficient however, showed no significant effect on biological filter performance; indicating that the performance benefits associated with highly uniform media may not be commensurate with cost. GAC was found to be significantly more resilient to backwashing in collapsed pulse and chlorinated modes, which impaired BOM removal in anthracite filters. This resilience imparts a high degree of operational flexibility to backwashing GAC filters. The significant decrease in BOM removal by anthracite filters can be minimized; however, by using an optimized backwashing technique. Collapsed pulse backwashing was found to have a significant effect on biological filter performance. When chlorinated collapsed pulse was used, filter cycles were significantly shortened by approximately 30 – 50% due to a sudden surge in effluent turbidity. This effect is thought to be the result of biofilm, damaged during the course of backwashing sloughing from the media. Extended terminal subfluidization wash was found to significantly reduce, and often eliminate filter ripening entirely. Additionally, the extended contact time with chlorine associated with chlorinated ETSW did not appear to have a significant effect on filter BOM removal. By eliminating filter ripening without compromising biological performance, ETSW shows promise for significant water and production cost savings by minimizing the filter-to-waste period during filter ripening. The presence of chlorine however, was associated with decreased DOC, 24 hours in to the filter cycle. This factor, combined with the negative interaction between chlorine and collapsed pulse suggests chlorinated wash water should be avoided in biological filtration systems like the ones investigated.