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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Impact de la station d'épuration des eaux de St-Adolphe-d'Howard sur le lac Ste-Marie, dans les Laurentides

Lamoureux, Christine January 2006 (has links)
No description available.
42

Temporal Sodium Flux In A Woodlot Soil Irrigated With Secondary Treated Effluent: The Implications For Sustainable Irrigation And Soil Management

Lucas, Steven Andrew January 2007 (has links)
This study reports results obtained and the approach taken in investigating the temporal sodium flux in a woodlot soil receiving secondary treated effluent at Branxton, NSW. Previous research has shown woodlot soils receiving secondary treated effluent undergo an increase in exchangeable sodium percentage (ESP) over time. Increased soil ESP influences micro-aggregate/soil pore stability and, particularly when subject to irrigation waters of specific low-electrolyte concentrations, results in decreased soil permeability and a subsequent need to reduce effluent application rates. Therefore, in irrigated woodlot soils it has been necessary to implement strategies to remove excess sodium from the root zone to maintain optimum permeability of the receiving soil, that is, maintaining the cation balance (as soil ESP) to promote optimum soil pore size. To maintain optimum permeability, an understanding is needed of temporal variations in the accumulation/leaching (flux) of sodium within a soil under secondary treated effluent irrigated conditions. The ability to define the sodium flux depends on the frequency of soil sampling and the ability to interpret the net loss/gain in soil sodium in relation to the applied hydraulic load over time. Past research has measured changes in soil ESP on an annual basis, or longer, making it impossible to interpret temporal sodium flux within a given year. The rate of change of soil ESP has ramifications for optimum permeability within an effluent irrigated woodlot. With respect to increasing/decreasing soil ESP, a major response of the clay particles within micro-aggregates is the deformation of conducting soil pores and reduced hydraulic conductivities. In addition, clay dispersion is governed by the soil ESP and electrolyte concentration of the infiltrating waters at the time, where dispersed clay particles may block conducting soil pores and further reduce hydraulic conductivity. Therefore, investigating the temporal sodium flux in conjunction with the temporal variation in electrolyte concentration of infiltrating waters will give greater insight into the response of effluent irrigated soils to sodium-rich waters over time. Three research aims were formed to investigate temporal sodium flux. These include: 1. To investigate trends in the dominant water balance components for a woodlot soil receiving secondary treated effluent (STE); 2. To examine temporal and spatial variation in both the water balance components and measured soil properties, particularly the sodium flux; and 3. To investigate the implications of the sodium flux on the loss of soil structure and drainage over time (dispersion events), particularly in relation to temporal changes in soil ESP and effluent SAR. Monitoring programs for water balance components and soil parameters covered the period January 2002 – October 2003. Every two months, soil samples were taken at designated sites and at different depths (10, 20, 40, 60, and 80 cm). These samples were analysed for exchangeable cations (Ca2+, Mg2+, Na+ and K+), from which the ESP values were derived. Also, this appears to be the first time that soil sampling at this frequency, which enables the temporal sodium flux to be determined, has been carried out. Column leaching experiments were also performed over the study period to illustrate the response of the woodlot soil, in terms of micro-aggregate stability, to hydraulic loads of varying SAR. Column leaching experiments also confirmed the rate of solute movement through the soil profile and the woodlot soil’s ability to bind/exchange sodium under different hydraulic loads and electrolyte concentrations. Soil extraction plate methods were used to determine wilting point and field capacity for these soils. The Sodium Adsorption Ratio (SAR), which is the solutional equivalent to soil ESP, was used to define the electrolyte concentration of the applied effluent and rainfall to the woodlot. The net loss/gain of exchangeable sodium at different depths and times was determined and compared with changes in water balance components and the measured volumetric soil water over time. The soil water surplus/deficit was recorded at a daily time-step and a cumulative approach was used to determine the long-term soil water surplus/deficit. In addition, variations in groundwater levels were monitored to observe if surplus irrigation events were reflected in temporal trends. As a result of determining the temporal variation in soil ESP, effluent and rainfall SAR, daily soil water deficit/surplus (short-term), cumulative soil water deficit/surplus (long-term) and volumetric soil moisture, temporal trends are presented. The sodium flux was then investigated by interpreting trends in the monitored data with respect to the dominant water balance components. All parameters were then used to model the potential dispersive behaviour of the receiving soil over time and depth, in relation to the volume and electrolyte concentration of the effluent and rainfall applied over time. The implications for soil structure and permeability depend on variations in soil ESP and effluent SAR. Results from this research show that soil ESP varied by as much as 24% over a four-month period and is shown to be a function of the sodium loading (from STE) and soil water surplus/deficit. On each sampling occasion, soil ESP generally increased with depth at all irrigated sites. Soil ESP at non-irrigated sites was much lower than irrigated sites, although the variability in soil ESP was much greater. Variations in SAR of the waters received by the woodlot soil (effluent and rainfall) over the study period ranged from 0.5 to 5.9. It is shown that the SAR range, coupled with variations in soil ESP, has ramifications for maintaining long-term soil structure. Soil structure at different sites within a woodlot will respond differently according to the soil ESP/effluent SAR relationship. The dispersive potential of soil at a given ESP receiving irrigation waters of known SAR was assessed in light of the relationship between soil ESP and effluent SAR. This showed the dynamic response of effluent irrigated soils to the long-term temporal variation in electrolyte concentration of rainfall/effluent. The relationship between soil ESP and effluent SAR is graphically presented as a continuum, which in turn can be used as a management tool for assessing the potential for dispersion of clay particles in a soil of known ESP and irrigated with waters of known SAR. By identifying trends in the temporal sodium flux, the optimum permeability of the receiving soil can be assessed in relation to the electrolyte concentration of the applied waters and the soil exchangeable sodium percentage (ESP). Secondary treated effluent application rates can then be corrected to prevent “dispersive” irrigation events over the long term and/or management strategies applied to remove excess sodium from the soil profile. The significance of the research is that a better understanding of the temporal dynamics of sodium in the soil profile will allow improved management of effluent irrigated woodlots, with the aim of making the practice sustainable with respect to controlling accumulating soil sodium and maintaining soil structure for future landuse. / PhD Doctorate
43

The Response of Wild Fish to Municipal Wastewater Effluent Exposures at Sites in Canada

Tetreault, Gerald 08 March 2012 (has links)
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.
44

Biodegradation of Estrogenic Steroidal Hormones

Kim, Sang Hyun 2010 August 1900 (has links)
Natural and synthetic estrogens are some of the most potent hormones detected in the environment. Agriculture fields often release higher concentrations of natural estrogens to the environment, but wastewater treatment plants (WWTPs) commonly release higher concentrations of synthetic estrogens. Estrogens can disrupt endocrine functions in wildlife and humans. Less attention has been paid to the fate and occurrence of estrogens in agricultural operations than WWTPs. Their fate is influenced by major mechanisms such as sorption and biodegradation. Sorption typically accounts for less than 10 percent of estrogen removal in WWTPs. However, biodegradation is a primary method for estrogen loss at high ammonia concentration in the agricultural and municipal operation. Less attention has been paid to the biodegradation kinetics of estrogens in the field application. Therefore, this dissertation focused on the occurrence of estrogens in agricultural fields and their biodegradation by a mixed culture and a pure culture. The estrogens in turkey litter amended fields might be biodegraded to some degree by turkey litter borne bacteria. The estrogen biodegradation by a mixed culture showed different mechanisms for each estrogen. E1 and E2 were easily degraded as a carbon source of the mixed culture. E3 and EE2 were favorable for cometabolic degradation by AOB. EE2 was not readily biodegraded by the mixed culture due to a steric hindrance of enzyme expression and EE2 metabolism in the ethynylgroup of EE2. The cometabolic kinetics of individual estrogen was evaluated by using a pure culture. The cometabolism of estrogen was demonstrated by a reductant model. This model appropriately estimated the cometabolic kinetics of individual estrogens. In addition, the effect of antibiotics on the hormone degradation was investigated in Sequencing Batch Reactors (SBRs). No significant difference was detected for the removal efficiency of target compounds in the SBRs in presence or absence of antibiotics (oxytetracycline and chlortetracycline) during long sludge retention time (SRT). However, the effluent organic matter (EfOM) was less decomposed with the presence of antibiotics, especially causing less degradation of the humic-like substances in EfOM. The results indicated the flux of antibiotics to WWTPs did not affect hormone degradation, but reduced the decomposition of humic-like substance. Finally, the findings from the research provide insight into how biodegradation influences estrogen removal in agricultural fields and municipal WWTPs. The models developed in this research yielded valuable predictive values for engineered systems.
45

none

Liu, Te-Jen 12 October 2004 (has links)
none
46

The effect of different carbon sources on reduction of nitrate in effluent from the mining industry : Olika kolkällors inverkan på reduktion av nitrat i processvatten från gruvindustrin

Lindberg, Hanna January 2014 (has links)
Mine water effluent contains high levels of nitrogen due to residues from undetonated ammonium- nitrate based explosives. Excess nitrogen in aquatic ecosystems can cause eutrophication. Within a mining area, tailings and clarification ponds have the potential to reduce nitrogen levels by biological uptake of nitrogen into growing algae and denitrification in pond sediments. A previous study at the LKAB Kiruna mine investigated the potential nitrogen removal within the tailings and clarification ponds. The study showed that about 1-10 tonnes of nitrogen were removed each year, and that the removal by denitrification was limited by carbon.  The aim of this master thesis was to investigate if additions of different carbon compounds could improve the denitrification in sediment from the clarification pond at the LKAB Kiruna mine site. It was also of interest to see if the composition of the edogenous microbial community involved in nitrogen reduction changed after the treatments. Samples of sediment and pond water were collected in January 2014 and a laboratory experiment was set up where sediment and water was incubated with carbon additions under anoxic conditions. Three different carbon sources were tested: sodium acetate, hydroxyethyl cellulose and green algae. Pond water without additional carbon was used as a control. The sediment was incubated eight weeks at 20 °C with weekly water exchange and carbon addition. The removed water was analyzed to determine the amount of nitrogen removed. At start and after ending the incubation, potential denitrification in the sediment was determined with an enzymatic assay and the size of the genetic potential of nitrogen reduction was determined.  At start, the enzymatic assay showed that the potential denitrification rate in the sediment of the clarification pond at the LKAB Kiruna mine was not immediately enhanced by addition of carbon. However, during the incubation the removal of nitrate was enhanced by external carbon sources. Algae were a good carbon source, since the denitrifying community grew, the potential denitrification increased four times after incubation and the removal of nitrate was next to complete in the end of the incubation. The addition of cellulose also enhanced the denitrification activity to some extent and the abundance of genes coupled to denitrification increased. Further studies are needed to assess the practical use of external carbon sources like algae and plant material and how they would function in and potentially also affect a large, cold and complex system like the LKAB mining site.
47

The influence of different factors on the drying rate of silage grass and development of predictive models

Wright, David Andrew January 1997 (has links)
No description available.
48

The Response of Wild Fish to Municipal Wastewater Effluent Exposures at Sites in Canada

Tetreault, Gerald 08 March 2012 (has links)
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.
49

Effects of hydraulic loading and laundry detergent on the operation of aerobic package treatment systems /

Hanna, K. Michael, January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 91-95). Also available via the Internet.
50

Aplicação da técnica de eletrofloculação no tratamento de efluentes têxteis / Application of the technique of eletrofloculation in the treatment of effluent textile.

Alexandre Andrade Cerqueira 10 April 2006 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A poluição dos corpos dágua proveniente dos efluentes têxteis provoca alterações em ciclos biológicos afetando principalmente a fotossíntese. Além disso, algumas classes de corantes podem ser carcinogênicos e/ou mutagênicos. Devido à dificuldade em se tratar estes efluentes, novas tecnologias têm sido investigadas. Neste contexto, a eletrofloculação surge com uma técnica promissora, devido à sua eficiência e possibilidade de reuso da água. O presente trabalho tem como objetivo estudar a aplicação do processo de eletrofloculação no tratamento de efluentes de uma indústria têxtil. O processo de eletrofloculação foi realizado em um reator de batelada utilizando eletrodos de ferro e alumínio. A influência dos seguintes parâmetros foi avaliada: natureza e distância do eletrodo, variação de pH, potencial elétrico aplicado e tempo de operação. Os resultados obtidos indicaram que o processo de eletrofloculação nas condições operacionais estudadas é uma alternativa tecnicamente viável para a remoção de DQO, cor e turbidez, a qual foi, respectivamente, de 87%, 95% e 100%. / The pollution of the stream waters through textille effluents causes alterations in biological cycles affecting the photosynthesis mainly. Moreover, some class of dyes can be carcinogenic and/or mutagenic. Due to difficulty in treating these effluents new technologies have been investigated. In the present work, electrofloculation appears to be a very promising technique, due to relatively high efficiency and possibility of water reuse. The present work emend has objective to study the application of electrofloculation in the treatment of effluents of a textile industry. The process was carried out in a batch reactor using electrodes either iron or aluminum. The influence of the following parameters was evaluated: nature and distance between electrodes, pH, electric potential applied and operation time. The results indicated that the process of electrofloculation in these operational conditions is a technical viable alternative for the removal of COD, color and turbidity, which were, respectively, of 87%, 95% and 100%.

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