No description available.

This thesis details the work completed in order to develop a hydrodynamic and nitrate transport and reaction model for Round Lake, a backwater on UMR Pool 8. This work begins with investigating the fundamentals of nitrogen removal in aquatic ecosystems and reviewing other combined hydrodynamic and nutrient modeling efforts. Field data were gathered to determine model boundary conditions and provide a basis for calibration and validation. Using this data, the flow regime in Round Lake was simulated. CFD applications to model particle residence times and species transport and reaction were used to analyze the effects local hydraulics have on nitrogen removal in the lake. Results demonstrated an ability for CFD to predict spatial variation of nitrate with this ecosystem.

Several health problems may be caused by excess nitrate in drinking water, the most important of which being methemoglobinemia, a potentially fatal disorder, in infants under six months of age. Many different parts of the world have been facing the problem of nitrate contaminated surface and groundwaters due in large part to excessive use of nitrate-based chemical fertilizers. In the Region of Waterloo, Ontario, Canada some groundwater sources have nitrate concentrations approaching the Health Canada and Ontario Ministry of the Environment maximum acceptable concentration (MAC) of 10 mg NO3--N/L. Finding a practical and economical way to reduce nitrate concentrations in representative groundwater in the Region of Waterloo was the overall objective of this research. To achieve this goal, nitrate removal technologies including biological denitrification, ion exchange (IX), reverse osmosis (RO), electrodialysis (ED), and chemical denitrification were reviewed and compared. IX and RO were found to be the most promising technologies for nitrate removal. They have also been approved by the United States Environmental Protection Agency (USEPA) as Best Available Technologies (BAT). To investigate the feasibility of IX and RO for nitrate removal from representative groundwater in the Region of Waterloo, bench-scale experiments were conducted and compared. These technologies could be considered for application at full- or point-of-use (POU)-scale. Decision support assistance for the selection of the appropriate technology for different technical and economical conditions is provided as an outcome of this work. Two nitrate-selective ion exchange resins (Dowex™ NSR-1 and Purolite® A-520E), two non-selective resins (Purolite® A-300E and Amberlite® IRA400 Cl), and a commercially-available RO POU device (Culligan® Aqua-Cleer® model RO30), which included a particle filter and a carbon block, were tested with deionized water and real groundwater.* IX results confirmed that production time before resin exhaustion was influenced by operating conditions, specifically bed depth as would be expected. It was also confirmed that the presence of competing anions (sulfate, chloride) and alkalinity adversely affected performance, with sulfate being the main competitor for nitrate removal. The extent of these effects was quantified for the conditions tested. At the end of the runs, the non-selective resins were prone to potential nitrate displacement and release into product water and are therefore not recommended. The nitrate-selective resins did not release previously adsorbed nitrate as their capacity became exhausted. Purolite® A-520E was identified as the best alternative amongst the four resins for removing nitrate from the representative groundwater source. The RO unit removed roughly 80% of the nitrate from groundwater. Background ions didn’t appear to compete with each other for removal by RO units, so RO might be a more appropriate technology than IX for nitrate removal from waters with high concentrations of sulfate or TDS. Since RO removes other background ions as well as nitrate, the product water of RO is low in alkalinity and can potentially be corrosive, if water from a small full-scale system is pumped through a communal distribution system. Post-treatment including pH adjustment, addition of caustic soda, and/or corrosion inhibitors may be required. While the carbon block did not play a substantial role with respect to removal of nitrate in the groundwater tested, a potential issue was identified when running RO systems without the carbon block. In deionized water (and presumably in very low alkalinity real waters) it was noted that RO nitrate removal efficiency dropped substantially as the alkalinity of the influent water approached zero. With respect to the scale of application of IX and RO devices, IX can be applied at full-scale without requiring large amounts of space. However, if feed water contains high concentrations of sulfate or TDS, nitrate leakage happens sooner and regeneration would be needed at more frequent intervals. Also, chloride concentrations in IX product water might exceed aesthetic objectives (AO) and should be monitored in cases of high feed water TDS. POU IX devices are not recommended when feed water nitrate concentration is high due to potential nitrate leakage into the product water when the resin is nearing exhaustion which increases public health risk. Issues associated with RO application at full-scale are high energy demand, low recovery, high costs, need of pre-treatment (fouling control), and post-treatment (corrosion control). On the other hand, POU RO devices may be acceptable since low recovery is of less importance in a household system, and product water corrosivity is less relevant. POU RO devices are preferable to POU IX units due to their lower risk of nitrate leakage into treated water. * Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Several health problems may be caused by excess nitrate in drinking water, the most important of which being methemoglobinemia, a potentially fatal disorder, in infants under six months of age. Many different parts of the world have been facing the problem of nitrate contaminated surface and groundwaters due in large part to excessive use of nitrate-based chemical fertilizers. In the Region of Waterloo, Ontario, Canada some groundwater sources have nitrate concentrations approaching the Health Canada and Ontario Ministry of the Environment maximum acceptable concentration (MAC) of 10 mg NO3--N/L. Finding a practical and economical way to reduce nitrate concentrations in representative groundwater in the Region of Waterloo was the overall objective of this research. To achieve this goal, nitrate removal technologies including biological denitrification, ion exchange (IX), reverse osmosis (RO), electrodialysis (ED), and chemical denitrification were reviewed and compared. IX and RO were found to be the most promising technologies for nitrate removal. They have also been approved by the United States Environmental Protection Agency (USEPA) as Best Available Technologies (BAT). To investigate the feasibility of IX and RO for nitrate removal from representative groundwater in the Region of Waterloo, bench-scale experiments were conducted and compared. These technologies could be considered for application at full- or point-of-use (POU)-scale. Decision support assistance for the selection of the appropriate technology for different technical and economical conditions is provided as an outcome of this work. Two nitrate-selective ion exchange resins (Dowex™ NSR-1 and Purolite® A-520E), two non-selective resins (Purolite® A-300E and Amberlite® IRA400 Cl), and a commercially-available RO POU device (Culligan® Aqua-Cleer® model RO30), which included a particle filter and a carbon block, were tested with deionized water and real groundwater.* IX results confirmed that production time before resin exhaustion was influenced by operating conditions, specifically bed depth as would be expected. It was also confirmed that the presence of competing anions (sulfate, chloride) and alkalinity adversely affected performance, with sulfate being the main competitor for nitrate removal. The extent of these effects was quantified for the conditions tested. At the end of the runs, the non-selective resins were prone to potential nitrate displacement and release into product water and are therefore not recommended. The nitrate-selective resins did not release previously adsorbed nitrate as their capacity became exhausted. Purolite® A-520E was identified as the best alternative amongst the four resins for removing nitrate from the representative groundwater source. The RO unit removed roughly 80% of the nitrate from groundwater. Background ions didn’t appear to compete with each other for removal by RO units, so RO might be a more appropriate technology than IX for nitrate removal from waters with high concentrations of sulfate or TDS. Since RO removes other background ions as well as nitrate, the product water of RO is low in alkalinity and can potentially be corrosive, if water from a small full-scale system is pumped through a communal distribution system. Post-treatment including pH adjustment, addition of caustic soda, and/or corrosion inhibitors may be required. While the carbon block did not play a substantial role with respect to removal of nitrate in the groundwater tested, a potential issue was identified when running RO systems without the carbon block. In deionized water (and presumably in very low alkalinity real waters) it was noted that RO nitrate removal efficiency dropped substantially as the alkalinity of the influent water approached zero. With respect to the scale of application of IX and RO devices, IX can be applied at full-scale without requiring large amounts of space. However, if feed water contains high concentrations of sulfate or TDS, nitrate leakage happens sooner and regeneration would be needed at more frequent intervals. Also, chloride concentrations in IX product water might exceed aesthetic objectives (AO) and should be monitored in cases of high feed water TDS. POU IX devices are not recommended when feed water nitrate concentration is high due to potential nitrate leakage into the product water when the resin is nearing exhaustion which increases public health risk. Issues associated with RO application at full-scale are high energy demand, low recovery, high costs, need of pre-treatment (fouling control), and post-treatment (corrosion control). On the other hand, POU RO devices may be acceptable since low recovery is of less importance in a household system, and product water corrosivity is less relevant. POU RO devices are preferable to POU IX units due to their lower risk of nitrate leakage into treated water. * Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Ammonium-nitrate based explosives (NH4NO3) used within the operations of Kiruna iron ore mine release nitrate (NO3-) into the environment, potentially having adverse effects on local river-systems. One way of reducing NO3- impacts to the environment is through a woodchip denitrifying bioreactor (DBR). Waste rock leachate is collected and passed through the bioreactor, where denitrifying microbial communities reduce NO3- to nitrogen gas (N2) using a carbon energy source. However, the efficiency of the DBR present in Kiruna iron ore mine has declined since the start of its operation leading to lower values of NO3-removal throughout the years.  Denitrification being a temperature dependent process, a heating device was installed to warm up the water prior to the DBR treatment to counterbalance this decrease. The effect of which has been assessed within this thesis. Chemical analyses encompassing NO3-, nitrite (NO2-), ammonium (NH4+), total organic carbon (TOC), phosphorus compounds (tot-P, PO4-P), and bacterial abundance were then investigated along a flowpath in the DBR. Overall, the results have shown that with an increase in temperature prior to the treatment, TOC, tot-P, PO4-P release was improved. Moreover, NO3- removal doubled compared to the previous year. TOC, tot-P and PO4-P are the result of the hydrolysis process, transforming the woodchips in available carbon source and providing nutrients for the bacteria to perform denitrification. Similarly, the bacterial abundance presented a significant increase with temperature. This suggest that both hydrolysis and bacteria growth enhancement with temperature ultimately participated in the improvement of the denitrification reaction. Moreover, a long-lasting effect of temperature on NO3- removal was observed during a following cold period as NO3- removal stayed above 45% after two months without heating. It is suggested that the cost of heating can be reduced by inducing “heat pulse” instead of continuous heating. Adding a heating system prior to treatment represents a promising solution for the future of sustainable mining, particularly for mines located in extreme climates such as Kiruna. / NITREM

No description available.

O nitrato nas águas subterrâneas é considerado um dos principais problemas com relação aos padrões de potabilidade estabelecidos pela Portaria MS nº 2914/2011, o limite é de 10 mg NNO3-/L, tendo em vista que a ingestão de altas concentrações de nitrato está associada a doenças como câncer e a metahemoglobinemia. As preocupações com o nitrato devem-se as concentrações insidiosas e persistentes deste íon registradas pela CETESB desde o início do monitoramento das águas subterrâneas em 1990. O presente trabalho propôs a avaliação de um processo alternativo para remoção de nitrato, trata-se de um sistema bioeletroquímico, também conhecido como MFC (Microbial Fuel Cells), que utiliza microrganismos para desnitrificação. Esse tratamento consiste no uso de processos biológicos potencializados pelo processo de eletrólise, aproveitando desta forma, os principais pontos característicos de cada processo de maneira combinada. O sistema foi testado em escala de bancada, e consiste basicamente em uma câmara anódica onde ocorre a oxidação da matéria orgânica e uma câmara catódica onde ocorre o processo de redução do nitrato a N2. Entre as câmaras é utilizada uma membrana de troca iônica de forma a permitir somente a passagem de prótons da câmara anódica para a catódica, além de impedir a difusão de oxigênio para a câmara catódica. O experimento realizou 8 testes variando a taxa de aplicação total de 2,88 a 11,52 L/dia com uma concentração 15 mg N-NO3-/L. Nos últimos dois testes ainda foi aplicada uma tensão externa. O sistema atingiu uma eficiência média de remoção de nitrato de 80,84 ± 16,73 %. As concentrações finais de nitrato permaneceram dentro dos padrões de potabilidade, com valor médio de 1,88 ± 2,03 mg N-NO3-/L, obtendo-se uma taxa de desnitrificação de 0,0498 ± 0,03 kg/m³.dia. O acúmulo de nitrito no sistema teve valor médio de 0,36 ± 0,37 mg N-NO2-/L. / Nitrate in groundwater is considered to be one of the main problems with regard to the potability standards established by Ordinance MS nº 2914/2011, the limit is 10 mg N-NO3-/L, considering that the intake of high concentrations of nitrate Is associated with diseases such as cancer and methemoglobinemia. Concerns with nitrate are due to the insidious and persistent concentrations of this ion recorded by CETESB since the beginning of groundwater monitoring in 1990. The present work proposed the evaluation of an alternative process for nitrate removal. This is a bioelectrochemical system, also known as MFC (Microbial Fuel Cells), which uses microorganisms for denitrification. This treatment consists in the use of biological processes potentiated by the electrolysis process, thus taking advantage of the main characteristic points of each process in a combined manner. The system was tested on a bench scale, and basically consists of an anodic chamber where the oxidation of organic matter occurs and a cathodic chamber where the process of nitrate reduction to N2 occurs. Between the chambers an ion exchange membrane is used in order to allow only the passage of protons from the anode chamber to the cathodic, in addition to preventing the diffusion of oxygen to the cathodic chamber. The experiment performed 8 tests varying the total application rate from 2.88 to 11.52 L/d with a concentration of 15 mg N-NO3-/L. In the last two tests an external voltage was still applied. The system achieved an average nitrate removal efficiency of 80.84 ± 16.73%. The final concentrations of nitrate remained within the potability standards, with an average value of 1.88 ± 2.03 mg N-NO3-/L, obtaining a denitrification rate of 0.0498 ± 0.03 kg/m³.d. The accumulation of nitrite in the system had an average value of 0.36 ± 0.37 mg N-NO2-/L.

O nitrato nas águas subterrâneas é considerado um dos principais problemas com relação aos padrões de potabilidade estabelecidos pela Portaria MS nº 2914/2011, o limite é de 10 mg NNO3-/L, tendo em vista que a ingestão de altas concentrações de nitrato está associada a doenças como câncer e a metahemoglobinemia. As preocupações com o nitrato devem-se as concentrações insidiosas e persistentes deste íon registradas pela CETESB desde o início do monitoramento das águas subterrâneas em 1990. O presente trabalho propôs a avaliação de um processo alternativo para remoção de nitrato, trata-se de um sistema bioeletroquímico, também conhecido como MFC (Microbial Fuel Cells), que utiliza microrganismos para desnitrificação. Esse tratamento consiste no uso de processos biológicos potencializados pelo processo de eletrólise, aproveitando desta forma, os principais pontos característicos de cada processo de maneira combinada. O sistema foi testado em escala de bancada, e consiste basicamente em uma câmara anódica onde ocorre a oxidação da matéria orgânica e uma câmara catódica onde ocorre o processo de redução do nitrato a N2. Entre as câmaras é utilizada uma membrana de troca iônica de forma a permitir somente a passagem de prótons da câmara anódica para a catódica, além de impedir a difusão de oxigênio para a câmara catódica. O experimento realizou 8 testes variando a taxa de aplicação total de 2,88 a 11,52 L/dia com uma concentração 15 mg N-NO3-/L. Nos últimos dois testes ainda foi aplicada uma tensão externa. O sistema atingiu uma eficiência média de remoção de nitrato de 80,84 ± 16,73 %. As concentrações finais de nitrato permaneceram dentro dos padrões de potabilidade, com valor médio de 1,88 ± 2,03 mg N-NO3-/L, obtendo-se uma taxa de desnitrificação de 0,0498 ± 0,03 kg/m³.dia. O acúmulo de nitrito no sistema teve valor médio de 0,36 ± 0,37 mg N-NO2-/L. / Nitrate in groundwater is considered to be one of the main problems with regard to the potability standards established by Ordinance MS nº 2914/2011, the limit is 10 mg N-NO3-/L, considering that the intake of high concentrations of nitrate Is associated with diseases such as cancer and methemoglobinemia. Concerns with nitrate are due to the insidious and persistent concentrations of this ion recorded by CETESB since the beginning of groundwater monitoring in 1990. The present work proposed the evaluation of an alternative process for nitrate removal. This is a bioelectrochemical system, also known as MFC (Microbial Fuel Cells), which uses microorganisms for denitrification. This treatment consists in the use of biological processes potentiated by the electrolysis process, thus taking advantage of the main characteristic points of each process in a combined manner. The system was tested on a bench scale, and basically consists of an anodic chamber where the oxidation of organic matter occurs and a cathodic chamber where the process of nitrate reduction to N2 occurs. Between the chambers an ion exchange membrane is used in order to allow only the passage of protons from the anode chamber to the cathodic, in addition to preventing the diffusion of oxygen to the cathodic chamber. The experiment performed 8 tests varying the total application rate from 2.88 to 11.52 L/d with a concentration of 15 mg N-NO3-/L. In the last two tests an external voltage was still applied. The system achieved an average nitrate removal efficiency of 80.84 ± 16.73%. The final concentrations of nitrate remained within the potability standards, with an average value of 1.88 ± 2.03 mg N-NO3-/L, obtaining a denitrification rate of 0.0498 ± 0.03 kg/m³.d. The accumulation of nitrite in the system had an average value of 0.36 ± 0.37 mg N-NO2-/L.

Capacitive deionization technologies have gained significant attention in recent years. The development and availability of a variety of materials have enabled the growth of research on electrosorption, which makes capacitive deionization increasingly attractive. This technology has a wide range of applications, such as softening, desalination and selective removal, each of which has been the focus of the experimental part of this work. The theoretical part is devoted to the issue of functioning of capacitive deionization, electrode material and especially the specific application. Water desalination is a major issue, given the global shortage of drinking water and the possibility of using capacitive deionization as a competitive method to conventional desalination methods. Conversely, softening and selective removal of ions can pose everyday problems both in the treatment of drinking water or pre-treatment of industrial water and in the treatment of wastewater. In this diploma thesis, it was proved that the method of capacitive deionization can be used to solve all the above problems. Although capacitive deionization is not a commercially available technology in the Czech Republic yet, it can be expected to be used more and more in the future.

As harmful algal blooms begin to appear in unexpected places such as rivers in predominantly forested systems, a better understanding of the nutrient processes within these contributing watersheds is necessary. However, these systems remain understudied. Utilization of high-resolution water quality data applied to deterministic numerical modeling has shown that a 0.42% watershed area backwater riparian wetland along the Ohio River floodplain can attenuate 18.1% of nitrate discharged from local mixed-use watersheds and improves in performance during high loading times due to coinciding increased hydrological connectivity and residence times of water in these wetlands. Loading from the Fourpole Creek watershed was typical for mixed-use systems at 3.3 kgN/ha/yr. The high-resolution data were used to improve boundary condition parameterization, elucidate shortcomings in the model structure, and reduce posterior solution uncertainty. Using high resolution data to explicitly inform the modeling process is infrequently applied in the literature. Use of these data significantly improves the modeling process, parameterization, and reduces uncertainty in a way that would not have been possible with a traditional grab sampling approach.