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Aquatic receiving environments have long been used to dilute municipal wastewater effluents (MWWE) which are the largest discharge by volume into the aquatic environment in Canada. These treated effluents are a complex mixture of environmental contaminants that includes natural and synthetic hormones, pharmaceuticals, industrial chemicals, nutrients and ammonia. Discharge of MWWE may lead to serious problems in aquatic environments such as eutrophication, hypoxia as well as increased occurrence of disease and toxicity in resident aquatic biota. Reproductive impairment in fish has also been widely reported in association with exposure to wastewaters. Recently, concerns have been raised about the potential for municipal effluents to cause endocrine disruption in fish and other organisms. The effects of MWWE on fish and fish populations in Canada are currently poorly understood. The overall objective of this thesis is to contrast the impact of MWWE discharged into two Canadian rivers on sentinel fish species across levels of biological organization ranging from biochemical responses to changes at the fish community level. Results from these studies support the development of robust effects-based biological monitoring approaches to assess the effectiveness of regulations and remedial actions for minimizing the effects of MWWE. Understanding the temporal changes in physiological and reproductive parameters across the annual cycle of a sentinel species is necessary to optimize biomonitoring programs. The annual variability in terms of survival, reproduction and energy storage in the Greenside Darter (Etheostoma blennioides), a potential sentinel species for the Grand River, Ontario, was documented at a reference site across two years. Variation in energy storage and reproductive development indicated by somatic indices (i.e., relative organ size) and steroid production suggest that biomonitoring can be optimized for this species by sampling in late fall or early spring (pre-spawning). With this new knowledge, field studies conducted with small bodied species, including Rainbow Darter (E. caeruleum), Brook Stickleback (Culaea inconstans) and Fathead Minnow (Pimephales promelas) have demonstrated that, when sampled during the appropriate season (e.g., pre-spawning), they can be used as effective biomonitoring tools to detect fish responses associated with exposure to MWWEs. Two sentinel fish species, Rainbow Darter and Greenside Darter, were then used to examine the impact of two MWWE discharges on fish in the Grand River, Ontario, relative to reference sites in two seasons (fall and early spring). Fish responses, in terms of energy storage (condition factor, liver size), energy utilization (gonadosomatic indices) and reproduction (in vitro sex steroid production, cellular development and intersex) were assessed at each site. Both sentinel species were longer and heavier downstream of the wastewater outfalls. However, these larger fish did not demonstrate consistent increases in condition and liver somatic indices. MWWE-exposed male Rainbow and Greenside Darters had impaired capacity to produce androgens in vitro, lower gonadosomatic indices and altered sperm cell staging. Exposed female fish also had impaired capacity to produce estrogens in vitro, however, they did not demonstrate differences in oocyte development. Male Rainbow and Greenside Darters collected downstream of both MWWE discharges showed increased incidence of intersex (33 - 100%) in contrast to very low occurrences of this condition in upstream agricultural and urban reference sites. This increased incidence of intersex coincided with reductions in gonadosomatic indices and capacity to produce steroids, demonstrating the ability of MWWE to alter the reproductive systems of these fish. The fish communities downstream of the the MWWE outfalls demonstrated differences in abundance, diversity, and species composition when compared to reference sites. MWWE exposed sites had few of the darter species that dominate the fish community at reference sites. More mobile fish species such as suckers (Catostomidae spp.) and sunfish (Centrarchidae spp.) were more common downstream of the outfalls, with occurances becoming more pronounced downstream of the second sewage discharge. Wascana Creek, Saskatchewan, downstream of the wastewater treatment plant for the City of Regina can be up to 100% treated municipal wastewater. Brook Stickleback and Fathead Minnow exhibited delayed spawning and altered gonadal development downstream of the wastewater outfall. Exposed male Fathead Minnows were feminized, having lower expression of secondary sexual characteristics (i.e., loss of nuptial tubercles, dorsal pad, and dorsal fin dot) and induction of the female egg-yolk precursor protein, vitellogenin. Fathead Minnows also showed cellular damage to the gills and kidneys. These responses indicate exposure to a variety of environmental contaminants in the effluent such as ammonia as well as endocrine disruptors. The potential effect of MWWE discharges in these two Canadian watersheds on fish responses was demonstrated across various levels of biological organization including reduced sex steroid production, altered gonadal development, reduction in gonadosomatic indices, delayed spawning, and changes in fish assemblages. An effects-based monitoring approach using sentinel species can be successfully applied to detect changes associated with MWWE outfalls, as long as sampling of sentinel species is conducted during optimal time periods (i.e., when somatic indices are maximized and variability among individuals is minimized). MWWE can impair the reproductive potential of fish beyond a threshold where impacts are expressed at higher levels of organization such as populations or communities. It is essential to make mechanistic linkages between responses at different levels to determine the overall potential impact of effluents on fish. The collection of responses across multiple levels of biological organization can complement and support development of biomonitoring approaches that are focused at the population and community levels such as those being proposed for MWWE in Canada.

Two small subarctic lakes were eutrophicated due to wastewater discharge from 1964. In 1975, a wastewater treatment plant was built and a recovery process started. This paper will: (1) compile the 1972–1974, 1978–1980 and 1985–1988 investigation data regarding phosphorous and microalgae for one of the lakes; (2) complement with unpublished data from 1985 and 2003; and (3) introduce a discussion regarding three alternatives for future development of the lakes in their last phase of recovery. In the latest investigation, 2003, the lakes were assessed as almost recovered. They had returned to an oligotrophic state, but not fully to a pre-sewage situation. In the upper lake, more heavily polluted, the total phosphorous levels had decreased from an average of 168 µg P/L in 1972–1974 to an average of 12 µg P/L in 2003. The phytoplankton biomass had decreased twentyfold during the same period, from 11.2 mg/L to 0.6 mg/L. The Secchi depth had increased from 1.3 m to 2.8 m. The low oxygen level in late winter was still not recovered, thereby profoundly affecting residential organisms in the lakes. The low winter oxygen is assumed to remain so for a long time due to phosphorus release from sediments in the lakes.

Surface waters subject to algal blooms have a high rate of fouling water treatment filtration membrane. These waters typically contain high concentrations of hydrophilic organic carbon compounds such as proteins and polysaccharides. These compounds have been found to contribute greatly to membrane fouling. In this study the fouling propensity, and the components of the fouling layer, for microfiltration (MF) and ultrafiltration (UF) membranes, were characterised for samples taken from a wastewater treatment plant with lagoons prone to algal blooms and a blue-green algae culture (Anabaena circinalis). It was found that the organic carbon compounds released during the growth phase (EOM) of Anabaena circinalis have a similar fouling propensity for UF than those released during the lysis phase (AOM), and a slightly higher fouling propensity for MF. However, due to the presence of higher UV-absorbing hydrophilic compounds, higher concentration of intracellular proteins and/or humic acid-like matter in the AOM, irreversible fouling was significantly higher during the lysis phase.

In today’s progressively urbanised society, there is an increasing need for cost-effective, environmentally sound technologies for the removal of nutrients (carbon, phosphorous, nitrogen) from polluted water. Nitrogen removal from wastewater is the focus of this thesis. Conventional nitrogen removal requires the two processes of aerobic nitrification followed by anoxic denitrification, which is driven by remaining reducing power. While most wastewaters contain a significant fraction of reducing power in the form of organic substrate, it is difficult to preserve the reducing power required for denitrification, due to the necessary preceding aerobic oxidation step. Consequently, one of the major limitations to complete N-removal in traditional wastewater treatment systems is the shortage of organic carbon substrate for the reduction of oxidised nitrogen (NO2-, NO3-), produced from nitrification. This thesis followed two main research themes that aimed to address the problem of organic carbon limitation in nitrogen removal from wastewater, by management of the oxygen supply. The first theme was the study of N-removal by simultaneous nitrification and denitrification (SND) in the novel reactor type, the sequencing batch reactor (SBR). It was aimed to increase understanding of PHB metabolism and the limiting factors of SND and then to develop a suitable on-line control strategy to manage the oxygen supply and optimise nitrogen removal by SND. The second main research theme was the application of the CANON(Completely Autotrophic Nitrogen-removal Over Nitrite) process for nitrogen removal from wastewater; a novel process that requires minimal oxygen supply and has the potential to completely circumvent the requirement for organic substrate in nitrogen removal because it is catalysed by autotrophic microorganisms – Anammox (anaerobic ammonium oxidisers) and aerobic nitrifiers. For study of the SND process, a completely automated 2 L sequencing batch reactor was developed with on-line monitoring of the dissolved oxygen concentration, pH and oxidation-reduction (ORP) potential. The SBR was operated continuously for up to 2 years and, due to its separation of different phases by time, enabled the study and optimisation of different microbial activities, including acetate uptake and conversion to PHB (feast phase), PHB hydrolysis and consumption (famine phase), nitrification and denitrification (and SND). All experimental work was performed using a mixed culture Project summary and acetate as the organic substrate. Acetate consumption and PHB production was studied under different oxygen supply rates to establish conditions that allow maximum conversion of acetate to PHB during the feast phase. Lower DO supply rates (kLa 6 – 16 h-1) resulted in preservation of a higher proportion of acetate as PHB than at higher DO supply rates (kLa 30 and 51 h-1). Up to 77 % of the reducing equivalents available from acetate were converted to PHB under O2-limitation, as opposed to only 54 % under O2-excess conditions, where a higher fraction of acetate was used for biomass growth. A metabolic model based on biochemical stoichiometry was developed that could reproduce the trends of the effect of oxygen on PHB production. Experimental findings and simulated results highlighted the importance of oxygen control during the feast phase of an SBR in preserving reducing power as PHB. To develop an oxygen management strategy for the aerobic famine phase,the effect of the dissolved oxygen (DO) concentration on SND, using PHB as the electron donor, was investigated. There was a clear compromise between the rate and the percentage of SND achieved at different DO concentrations. A DO setpoint of 1 mg L-1 was optimal for both the percentage of SND (61 %) and rate of SND (4.4 mmol N. Cmol X-1. h-1). Electron flux analysis showed that most SND activity occurred during the first hour of the aerobic famine period, when the oxygen uptake rate (due to NH4 + and PHB oxidation) was highest. Aerated denitrification ceased as soon as NH4 + was depleted. The presence of NH4 + provided an oxygen “shield”, preventing excessive penetration of oxygen into the flocs and creating larger anoxic zones for SND. PHB degradation was first order with respect to the biomass PHB concentration (dfPHB/dt = 0.19 . fPHB). The slow nature of PHB degradation made it a suitable substrate for SND, as it was degraded at a similar rate to ammonium oxidation. While DO control during the aerobic famine phase could increase nitrogen removal via SND, total N-removal in the SBR was still limited by the availability of reducing power(PHB) in the anoxic phase. The length of the aerobic phase needed to be minimised to prevent over-oxidation of PHB after NH4 + depletion. The specific oxygen uptake rate (SOUR) was found to be an effective on-line parameter that could reproducibly detect the end-point of nitrification. A simple method was developed for continuous, on-line measurement of the SOUR, which was used for automated adjustment of the aerobic phase length. Minimisation of the aerobic phase length by feedback control of the Project summary SOUR improved nitrogen removal from 69 % (without phase length control) to 86 %, during one cycle. The SOUR-aeration control technique could successfully adapt the aerobic phase length to varying wastewater types and strengths and to varying aeration conditions. The medium- and long-term effects of oxygen management on nitrogen removal was investigated by operating the SBR continuously for up to one month using DO control throughout all stages of the SBR, i.e. oxygen-limitation during the feast phase, a DO setpoint of 1 mg L-1 during the famine phase and SOUR controlled aerobic phase length. Complete oxygen management resulted in minimisation of the amount of PHB that was oxidised aerobically in each SBR cycle and caused an accumulation of cellular PHB over time. The increased availability of PHB during aeration resulted in a higher SOUR and increased N-removal by SND from 34 to 54 %. After one month of continuous SBR operation, the settling efficiency of the biomass improved from 110 mL . g-1X to less than 70 mL . g-1X and almost complete N-removal (9 %) was achieved via SND during aeration, however at a reduced rate (1.5 mmol Cmol X-1 h-1). Therefore, long-term oxygen management resulted in biomass with improved settling characteristics and a higher capacity for SND. Results of the first main research theme highlighted the importance of aeration control throughout all stages of the SBR for maximum N-removal via SND. The CANON process was investigated as an alternative to the use of conventional activated sludge for treatment of wastewaters limited by organic carbon substrate. The initial study of the CANON process was performed at the Kluyver Laboratory in Delft, the Netherlands, using an already established Anammox enrichment culture. The effect of extended periods of NH4 +-limitation on the CANON microbial populations was studied, to examine their ability to recover from major disturbances in feed composition. The CANON process was stable for long periods of time until the N-loading rate reached below 0.1 kg N m 3 day-1, when a third population of bacteria developed in the system (aerobic nitrite oxidisers), resulting in a decrease in N-removal from 92 % to 57 %. Nitrite oxidisers developed due to increased levels of oxygen and nitrite. This highlighted the requirement for oxygen control during the CANON process to prevent increased DO levels and growth of undesired microbes. To initiate the CANON process from a local source, Anammox was enriched from local activated sludge (Perth, Western Australia). FISH analysis (fluorescence in situ hybridisation) of the enriched Anammox strain showed that it belonged to the Order Planctomycetales, Project summary the same as all other identified Anammox strains, but represented a new species of Anammox. The enrichment culture was not inhibited by repeated exposure to oxygen, allowing initiation of an intermittently-aerated CANON process to achieve sustained, completely autotrophic ammonium removal (0.08 kg N m-3 day-1) for an extended period of time, without any addition of organic carbon substrate. Dissolved oxygen control played a critical role in achieving alternating aerobic and anaerobic ammonium oxidation. The main conclusion drawn from the study is the important role of oxygen management in achieving improved nitrogen removal. A careful oxygen management strategy can minimise wastage of reducing power to improve PHB-driven SND by activated sludge and can prevent major disturbances to the population balance in the CANON system. Oxygen management has the potential to reduce aeration costs while significantly improving nitrogen removal from wastewaters limited by organic carbon.

Thesis (M. S. - Soil, Water, and Environmental Science)--University of Arizona, 1998. / Includes bibliographical references (leaves 61-69).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 232-241). Also available via the Internet

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 78-86). Also available via the Internet.

An increase in anthropogenic activity has led to the heightened levels of pollution entering aquatic systems. These excessive concentrations of heavy metals, nitrogen (N), and phosphorus (P) in water bodies can lead to several adverse impacts, such as eutrophication and human health risks. Therefore, the removal of pollutants from wastewaters, prior to their discharge into the natural environment, is of paramount importance. However, conventional wastewater treatment (WWT) technologies have their limitations; for instance, large capital/operational costs, and incomplete removal of contaminants. Therefore, innovative and more effective treatment technologies are required. Macro-algae typically have high growth and solar energy conversion rates, and are able to sequester nutrients, utilise CO2, and adsorb metals from aquatic environments. Therefore, algae may have potential applications in WWT. Furthermore, costs could be negated by the production of renewable algal biomass which may have a variety of commercially exploitable applications. However, issues such as poor selection of species or cultivation systems, and a lack of understanding of the influence of biological, chemical and physical factors, particularly in a highly dynamic wastewater environments, has led to varied results and prevented algal WWT becoming a widespread reality. In this thesis the algae Cladophora coelothrix and Cladophora parriaudii were studied as potential organisms for implementation into WWT. In addition to the features mentioned above, Cladophora was selected due to its ubiquity, filamentous morphology, which minimises harvesting costs, as well as their natural dominance and bloom forming behaviour in nutrient-rich environments. The influence of dewatering techniques, environmental factors, and nutrient regime upon the growth, nutrient/metal removal, and biochemical composition of the biomass were assessed. The first aspect of the thesis was an abiotic screening process, in order to investigate the robustness of Cladophora and its suitability for WWT applications on a fundamental level. Good rates of growth (4-13.3% d-1) and nutrient removal (45.2-99.9%) were observed throughout the screening process, except under the most extreme of conditions, e.g. pH 3. This indicated that Cladophora are potentially suitable for treating a broad range of wastewaters and merit further research to improve its potential applicability for WWT applications and commercial realisation. For instance, developing a reliable and accurate method for fresh weight (FW) assessment and hence productivity estimation. The determination of growth rate via FW measurement is one of the most basic aspects of algal biology, yet no standardised method exists for filamentous macro-algae. A variety of FW methods were systematically assessed in terms of accuracy and physiological impact. Methods involving mechanical pressing to dewater the biomass resulted in >25% reduction in the final biomass yield, compared to control cultures. The best method for FW determination employed a reticulated spinner, which was rapid, reliable, and easily standardised. Furthermore, this approach ensured accurate growth estimation with minimal physiological impact, measured as growth, maintenance of structural integrity and nutrient removal. This indicates that the method developed has the potential for widespread application in macro-algal cultivation, as such the method was employed throughout this thesis. The influence of nutrient regime on growth, biochemical composition, and bioremediation capacity was studied for both species of Cladophora. The nutrient regimes tested, representative of a broad variety of wastewaters, included four different N/P ratios, four N sources (ammonium, nitrate, nitrite and urea), and six different equimolar N source combinations provided at two N/P ratios. There were clear differences in performance between the two species, with higher rates of growth observed in all instances by C. parriaudii (4.75-11.2% d-1 vs. 3.98-7.37% d-1). Furthermore, ammonium was removed preferentially, whereas urea was removed secondarily. However, the presence of urea in the medium enhanced growth and uptake of the other co-existing N-forms, and yielded a carbohydrate-rich biomass (37.6-54% DW). These findings demonstrate that algal strain selection is important for treating wastewaters with specific nutrient profiles. In addition, results from this study suggest that nutrient regimes can be tailored to produce biomass with certain properties or characteristics, which make it suitable for further, potentially commercially viable, applications, such as metal biosorption. Since the biochemical characteristics of algal biomass were shown to be affected by nutrient regime, the final chapter describes research investigating the influence of nutritional history on metal biosorption. C. parriaudii was cultivated under different nutrient regimes to produce biomass of varying biochemical composition. This biomass was then used for metal removal, with maximum removal rates ranging from 1.08-2.35 mmol g1, 0.3-0.62 mmol g-1, 0.22-0.48 mmol g-1, and 0.43-0.61 mmol g-1 for Al2+, Cu2+, Mn2+, and Pb2+, respectively. Observations from this work indicate that metal removal is achieved by various mechanisms including adsorption, ion exchange, complexation and micro-precipitation, and that the biosorption efficacy is dependent upon the number and type of functional groups present, which are in turn influenced by the cultures nutrient regime. Overall, this study demonstrates the inter-relatedness of biological, chemical, and physical factors on algal growth, nutrient removal, biochemical composition, and metal biosorption. Results from this work have highlighted the need for standardisation in protocols, increased understanding of the influence of algal selection and nutrient characteristics in bioremediation, and highlighted the importance of considering biological aspects, specifically nutritional history, in biosorption studies.

This thesis presents the synthesis and characterization of copper oxide nano photocatalyst for wastewater purification using visible light. The presented copper oxide nano material can serve as a low-cost and green technology for environmental applications. Uniform cubic, octahedral and rhombic dodecahedral Cu2O nano crystals with a size of 300-600 nm were synthesized using a simple hydrothermal method. The rhombic dodecahedral Cu2O nano crystals are highly active when driven by low-power white LEDs as a light source. In comparison with other reported photocatalysts, the Cu2O nano crystals in this work show a much higher reaction rate and lower electrical energy per order. The reaction rate and photoefficiency are found to be highly correlated with the irradiated photon flux. The surface termination and facet orientation of Cu2O nano particles were accurately tuned by adjusting the amount of hydroxylamine hydrochloride and surfactant. It is found that Cu2O nano particles with Cu-terminated (110) or (111) surfaces show high photocatalytic activity, while other exposed facets show poor reactivity. The density functional theory simulations confirm that the sodium dodecyl sulfate surfactant can lower the surface free energy of Cu-terminated surfaces, increasing the density of exposed Cu atoms at the surfaces, and thus benefiting the photocatalytic activity. It also shows that the poor reactivity of Cu-terminated Cu2O (100) surface is due to the high energy barrier of holes at the surface region. Amorphous CuxO nano flakes with a thickness of 10 to 50 nm were prepared through the dye-assisted transformation of rhombic dodecahedral Cu2O nano crystals under facile hydrothermal condition. The amorphous CuxO nano flake consists of a combination of Cu(I) and Cu(II) with a ratio close to 1:1. It shows enhanced photocatalytic reactivity towards the degradation of methyl orange compared to rhombic dodecahedral Cu2O nano crystals with all active (110):Cu facets. The chemical composition and architecture remain the same after repeating degradation tests. The high surface-to-volume ratio contributes to its better photocatalytic performance while its low surface energy calculated by the density functional theory simulations explains its improved stability. The as-obtained photocatalysts are able to degrade a wide range of aromatic organics including toluene, chlorobenzene and nitrobenzene effectively. We also demonstrate the capability of decontaminating a wide range of aromatic organics in industrial wastewater that comes from an oil company.