The low capital and operating costs of aerated lagoons has lead to their extensive use in rural areas as a method of wastewater treatment. Although the performance of the system depends directly on the hydraulic mixing, there is currently no consensus on the key hydraulic parameters that influence the mixing of these lagoons. Tracer studies were performed on the St-Hermas aerated lagoon and a dynamically similar laboratory model to determine the effects of the water flow rate and the aeration rate on the performance of these aerated lagoons, to evaluate the method of dynamic similarity used to design the laboratory model and to evaluate the accuracy of predictive empirical dispersion models. The results were analysed using flow visualisation, simple observational and mathematical Retention Time Distribution (RTD) techniques and various hydraulic models. From these results it is concluded that the water flow rate and the aeration rate both significantly affect the hydraulic mixing of aerated lagoons, with the water flow rate being the dominant parameter. Furthermore, it is proven that the method of dynamic similarity used in this research is valid and that the only dispersion model that predicted reasonably accurate results was Arcievala (1981). An additional finding during the course of this research indicates that tracer study E-curves must be developed to completion in order to ensure conservation of mass and accurate analytical results.

This study is concerned with the biodegradation of polycyclic aromatic hydrocarbons (PAHs), particularly the utilization of biological processes in the bioremediation of PAH-contaminated soils. In this regard, the effects of the contaminant bioavailability and the redox environment on the biodegradation process have been investigated. / First, the mineralization of naphthalene in soil/water systems under denitrifying conditions has been studied. Results showed that naphthalene mineralization is influenced by its availability to the microbial population, which in turn is a function of the compound initial concentration, the sorption/desorption characteristics of the soil/contaminant complex and the organic content of the soil. / Second, the biodegradation of four PAH compounds, acenaphthene, acenaphthylene, fluorene and anthracene, in a soil/water system under four redox environments has been studied. Both aerobic and denitrifying environments supported appreciable PAH biodegradation rates. The denitrifying environment was chosen for a further experiment to investigate the performance of a bioreactor system in treating PAH-contaminated soils. Results showed that by enlarging the scale of the reactor by approximately eight times and simultaneously reducing the mixing intensity of the soil slurry, the biodegradation rates of the PAH compounds remained virtually unchanged.

Mushroom tyrosinase (polyphenol oxidase, EC 1.14.18.1) was investigated as an alternative to peroxidase, enzymes for the catalytic removal of phenolic compounds from wastewaters. The maximum catalytic activity was observed at pH 7; however, significant activity was observed at pHs ranging from 5 to 8. Tyrosinase was unstable under acidic conditions and at elevated temperatures. The activation energy for thermal inactivation of tyrosinase was determined to be 1.85 kJ mol-1 at pH 7. The transformation of phenols catalysed, by tyrosinase was investigated as a function of pH, initial phenol concentration, and additives. Phenol was transformed successfully with tyrosinase, over a wide range of pH (pH 5--8) and a wide range of initial concentrations (0.5 mM--10 mM). Some chlorinated phenols were also successfully transformed with tyrosinase. Polyethylene glycol and chitosan did not improve the transformation efficiency of phenol. However, chitosan was successfully used to remove coloured, products resulting from treatment Since coagulation with aluminium sulfate failed, the colour removal induced by chitosan addition appeared to be the result of simultaneous coagulation and adsorption mechanisms. Minimum doses of chitosan required to achieve 90% of colour removal were logarithmically related to the quantity of phenol treated. All solutions of phenol and chlorophenols treated with tyrosinase, had substantially lower toxicities, than their corresponding initial toxicities. Chitosan addition enhanced the reduction in toxicity very effectively. The toxicities of the phenol solutions treated with tyrosinase were markedly lower than previously reported toxicities of solutions treated with peroxidase enzymes.

Water demand management attempts to balance the supply of and demand for water by controlling the competing water demands. It realizes the change by influencing peoples' behavior with respect to water use. Water demand management (WDM) is necessary in water scarce regions like Barbados. The Government of Barbados has recognized the need for WDM as demonstrated by the implementation of measures such as universal metering and water pricing. / This research looks at the impact of water pricing and metering on residential water use in Barbados. Econometric demand models of residential water use are developed to assess the potential of pricing policies to conserve water. Price elasticities between -0.18 and -0.93 were obtained suggesting that pricing policies can be used to reduce and control residential water consumption in Barbados. The results of the models are then used to investigate the impact of different rate structures on water use and revenue generation. It is predicted that a 26% decrease in water demand and a 52% increase in revenue collected from water bills would be achieved if the 1997 proposed water rate increase is implemented. In addition, results indicate that water production decreased by 12% from 1997 to 2000, coinciding with the implementation of the Universal Metering Program. However, per-capita consumption has been on the rise in recent years suggesting that metering must be accompanied by a substantial increase in price to encourage water conservation.

The hydraulic behavior and mixing processes in wastewater basins are studied experimentally in a laboratory scale model. The laboratory basin is modeled after a full scale aerated lagoon system operating in Saint-Julie, Quebec. Three experimental techniques are used to reach the objectives: (i) video flow visualization, (ii) tracer studies and (iii) two-dimensional flow measurements using hot-film anemometry. Experiments are conducted on non-aerated basins, as well as on artificially aerated basins. / The flow visualization and flow measurements show that the hydraulic behavior of non-aerated wastewater basins is very complex, due to the formation of flow patterns such as stagnant zones and recirculation. The location and size of these flow patterns are determined using the measured velocity flow field and the flow visualization images. Mixing in these basins is highly non-uniform since flow is clearly segregated into high-velocity and low-velocity areas. The exchange between these areas is very low, affecting the distribution of solids and contaminants. / When artificial aeration is introduced, mixing becomes more uniform. Flow measurements and visualization indicate that the size of stagnant zones and the extent of recirculation decreases. The tracer studies show that, in general, aeration tends to decrease the actual residence time of the waste material. Calculation of the dispersion number, d, and the dead volume, Vd, are not sufficient to characterize the effect of aeration on mixing. / The understanding of mixing and transport mechanisms in wastewater basins is important, because such basins are often used in applications which require settling or mixing of solids and contaminants.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 2958. Adviser: Michael J. Plewa. Includes bibliographical references (leaves 155-168) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6585. Adviser: Marcelo H. Garcia. Includes bibliographical references (leaves 134-143) Available on microfilm from Pro Quest Information and Learning.

Recently, there has been an increased concern of the potential effects of pharmaceuticals, personal care products (PPCPs) and endocrine disrupting compounds (EDCs) in drinking water. Their presence in surface waters has resulted in the skewing of sex ratios in aquatic biota and the effect on humans, as yet, remains unknown. Investigation into the effective removal of these compounds by water treatment plants (WTPs) has shown that conventional treatment processes are not very effective in removing these trace compounds. Studies have shown PPCPs and EDCs have been successfully removed by commercial nanofiltration (NF) and reverse osmosis (RO) membranes, but have low flux and high cost. North American WTPs, using membrane separation processes, are typically equipped with microfiltration (MF) or loose ultrafiltration (UF) membranes which, thus far, have proven ineffective for the removal of these target compounds. This thesis focuses on the development of a tight charged UF membrane that effectively removes PPCPs and EDCs from drinking water while still maintaining a high flux and is cost effective. Novel membranes were developed by incorporating charged surface modifying macromolecules (CSMMs) in the manufacturing of polyether sulfone (PES) based membranes. The charged additives were expected to enhance the removal of PPCPs and EDCs by charge repulsion. Controls and three different CSMM (DEG-HBS, DEG-HBC and PPG-HBC) blended membranes were prepared at three different casting conditions and subsequently evaluated for various properties: flux, molecular weight cut-off (MWCO), porosity, charge and contact angle. Experimental membranes were further evaluated for the removal of four representative target compounds, sulfamethazine (SMZ), carbamazepine (Carb), bisphenol A (BPA) and ibuprofen (IB). Removal by a commercial nanofiltration membrane, NF270 (DOW/FilmTec) was compared to the experimental membranes. Removal results from the experimental membranes indicate membranes were unable to sustain effective removal of the target compounds. Typically, removal was initially high but decreased over the run. Membrane characteristics showed membranes had significantly larger pores than the target compounds indicating size exclusion was not the removal mechanism. Charge results indicated CSMM blended membranes were generally unchanged from the control membrane indicating, in addition to the unsustained removal, that charge repulsion was not the removal mechanism. From the shape of the removal curves, it is assumed the removal mechanism is the result of membrane adsorption. The CSMMs were found to have modified the membranes, though not sufficiently, to be considered significantly different than the controls in many respects. Membrane characteristics varied as a result of each CSMM incorporated and depending on each casting condition. Contact angle results for both PES-DEG-HBS and PES-PPG-HBC membranes at all three casting conditions increased in comparison to the controls, presumably because of changes in surface roughness. PES-DEG-HBC, on the other hand, decreased in contact angle at 18%, and increased in contact angle at 20% in comparison to the respective controls. Incorporation of migration time, particularly in the case of DEG-HBC, increased membrane flux without affecting MWCO. Increased PES concentration (from 18 to 20%) saw an increased target compound removal. With the success of the DEG-HBC CSMM, incorporation of migration time at higher PES concentrations appears promising for achieving the desired characteristics. It is recommended that further optimization using CSMM DEG-HBC at increased PES concentrations with migration time be investigated for this application.

In September 2005, Health Canada took on the development of a Source Water Quality Indicator for Canada. The main objective was to develop a methodology by which source water quality could be linked to public health, the environment, society, and economy; and measured, tracked, and reported in the form of an indicator for decision making. A Treated Water Quality Indicator was also introduced to bridge the gap between source water quality and human health. With Federal/Provincial/Territorial and academic support, research into the approach and development of a conceptual design, parameter selection rationale, and two tools for the indicator calculations, along with recommendations for future work were completed. The tools developed included a modified Canadian Council of Ministers of the Environment water quality index calculator, and a Treatability Ranking tool (that determined the complexity of treatment required to achieve safe drinking water). The results of this project are described herein.

The objective of this study is to promote photocatalytic wastewater treatment by proposing a reactor design that employs a catalyst-coated, rotating, corrugated drum to increase the surface area, induce agitation and promote reactant and photon transfer to the surface. Corrugation profiles with surface areas ranging from 405 cm2 to 3650 cm2 were considered---the addition of corrugations improved the phenol degradation rate by up to 200%. Based on an analysis of rotational speed and initial pollutant concentration, the reaction was found to be limited by the kinetics at 20 ppm and 40 ppm, but limited by phenol transfer to the reaction sites at 5 ppm. Finally, Langmuir-Hinshelwood kinetics was applicable with an average phenol adsorption coefficient of 0.120 L/mg and an increasing overall reaction rate constant with surface area. Further studies are necessary for the industrial use of such a reactor design including treatment of wastewater with varying characteristics, reactor design scaling and the applicability of this design for solar-activated applications.