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Artigos de revistas sobre o assunto "Trace organic removal"
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Trinh, T., B. van den Akker, R. M. Stuetz, H. M. Coleman, P. Le-Clech e S. J. Khan. "Removal of trace organic chemical contaminants by a membrane bioreactor". Water Science and Technology 66, n.º 9 (1 de novembro de 2012): 1856–63. http://dx.doi.org/10.2166/wst.2012.374.
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Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24–68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.
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Hajibabania, S., A. Verliefde, J. E. Drewes, L. D. Nghiem, J. McDonald, S. Khan e P. Le-Clech. "Effect of fouling on removal of trace organic compounds by nanofiltration". Drinking Water Engineering and Science 4, n.º 1 (21 de dezembro de 2011): 71–82. http://dx.doi.org/10.5194/dwes-4-71-2011.
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Abstract. The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l−1) were used to simulate fouling in nanofiltration under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.
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Hajibabania, S., A. Verliefde, J. E. Drewes, L. D. Nghiem, J. McDonald, S. Khan e P. Le-Clech. "Effect of fouling on removal of trace organic compounds by nanofiltration". Drinking Water Engineering and Science Discussions 4, n.º 1 (9 de setembro de 2011): 117–49. http://dx.doi.org/10.5194/dwesd-4-117-2011.
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Abstract. The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l−1) were used to simulate fouling in NF under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.
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Loi-Brügger, A., S. Panglisch, G. Hoffmann, P. Buchta, R. Gimbel e C. J. Nacke. "Removal of trace organic substances from river bank filtrate – performance study of RO and NF membranes". Water Supply 8, n.º 1 (1 de abril de 2008): 85–92. http://dx.doi.org/10.2166/ws.2008.021.
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Producing drinking water from raw waters like river bank filtrate nowadays requires the safe removal of ever new emerging organic substances. At present, in Germany perfluorinated organic compounds are heavily discussed. When it comes to trace organics removal, reverse osmosis (RO) and nanofiltration (NF) are alternatives to conventional bank filtrate treatment technologies like ozonation and activated carbon adsorption. However, the trace organics removal capabilities of dense membranes are still under investigation. Questions about concentrate disposal strategies are still open. The paper presents results from lab-scale and pilot studies which were conducted for the project planning of a 1,100 m3/h NF plant treating river Rhine bank filtrate. Membranes from loose NF to dense RO were investigated spiking the raw waters with trace organic substances which usually pass the soil passage and to some extent even the conventional treatment process. The results showed high retention capabilities of the more dense membranes, even under ageing conditions.
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Jekel, M., e S. Gruenheid. "Bank filtration and groundwater recharge for treatment of polluted surface waters". Water Supply 5, n.º 5 (1 de dezembro de 2005): 57–66. http://dx.doi.org/10.2166/ws.2005.0039.
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Investigations on the behavior of different bulk organics and trace organic compounds at a bank filtration site at Lake Tegel in Berlin, Germany, and in a long retention soil column system are reported. The objective of the research was to assess important factors of influence for the degradation of bulk and trace organics. More than two years of monitoring for the bulk parameter DOC proved that the redox conditions significantly influence the DOC-degradation rates but not necessarily the residual concentration. LC-OCD measurements confirmed that the change in character is comparable for aerobic and anoxic/anaerobic infiltration. Only the fraction of polysaccharides shows a better removal under aerobic conditions. Furthermore, adsorbable organic iodine (AOI) measurements revealed a more efficient degradation of AOI and AOBr under anoxic/anaerobic conditions. The moznitoring of the single organic pollutants Iopromide, Sulfamethoxazole and naphthalenedisulfonic acids showed that the redox conditions have an influence on the degradation behavior of some of the monitored compounds. Iopromide was efficiently removed at all times, but no evidence for a dehalogenation under oxic conditions was found. Sulfamethoxazole showed a better removal under anoxic/anaerobic conditions. The very stable 1.5-naphthalenesulfonic acid was not removed under either redox condition.
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Bozkaya-Schrotter, B., C. Daines, A. S. Lescourret, A. Bignon, P. Breant e J. C. Schrotter. "Treatment of trace organics in membrane concentrates I: pesticide elimination". Water Supply 8, n.º 2 (1 de julho de 2008): 223–30. http://dx.doi.org/10.2166/ws.2008.056.
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The objective of this study was to eliminate organic micropollutants in the membrane system concentrates, which is produced by drinking water production plants, in order to protect existing water resources. This work is divided into two parts, pesticide elimination (I) and natural organic matter removal (II) in membrane system concentrates. Seven commonly detected pesticides in French surface waters, i.e. atrazine, sulcotrione, bentazone, isoproturon, diuron, glyphosate and acetochlore, were selected as the model micropollutants. Removal/degradation of these pesticides was studied by testing conventional processes employed for potable water production, i.e. adsorption, oxidation by ozone and clarification. Only partial removal of these pesticides was achieved with conventional processes. Removal of nonpolar pesticides was obtained by adsorption and rapid degradation of most of the pesticides was observed with low ozone dosages, except for atrazine and its metabolites. On the other hand, only the phosphonate-based pesticides were removed by clarification. By combining these processes, however, almost complete removal of the selected pesticides was achieved. Simultaneous ozonation and adsorption in the same reactor seems to be the most promising option for this study.
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Nghiem, Long D., Nichanan Tadkaew e Muttucumaru Sivakumar. "Removal of trace organic contaminants by submerged membrane bioreactors". Desalination 236, n.º 1-3 (janeiro de 2009): 127–34. http://dx.doi.org/10.1016/j.desal.2007.10.059.
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Xu, Dong Ying, e Xi Wu Lv. "The Research of Degradation about 1,2,4-Trichlorobenzene by Microorganism on Different Experiment Condition". Applied Mechanics and Materials 178-181 (maio de 2012): 666–70. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.666.
Texto completo da fonteResumo:
Artificial media was used to enrich microbe and improve the water resource quality, therefore trace quantity organic pollutants of 1,2,4-Trichlorobenzene were biodegraded. The result of the experiment showed that, after domestication, the micro association enriched in the assembled medium could remove corresponding trace quantity organic pollutants in some concentration. When the temperature was 30 degree centigrade, the pH was between 6 and 9, the effect was the best about the removal on trace-quantity-organic pollutants water. A strain of bacteria was separated．At the same time, the congener trace quantity organic pollutants could be biodegraded. When the HRT was 6 days, the removal of trace quantity organic pollutants was between 70%～95%. It is evident that the trace quantity organic pollutants of 1,2,4-trichlorobenzene in the source water quality from Meiliang Bay in Taihu Lake can be well degraded by enriched microbes on the artificial media.
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Xu, Dong-ying. "The Research of Degradation about 1,2,4-Trichlorobenzene by the Artificial Media in Microbe Enrichment". Advances in Materials Science and Engineering 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/739693.
Texto completo da fonteResumo:
Artificial media were used to enrich microbe and improve the water resource quality; therefore trace quantity organic pollutants of 1,2,4-trichlorobenzene were biodegraded. The result of the test showed that, after domestication, the microassociation enriched in the assembled medium could remove corresponding trace quantity organic pollutants in some concentration. When the temperature was 30 degree centigrade, and the pH was between 6 and 9, the effect about the removal on trace-quantity-organic pollutants water was the best. A strain of bacteria that could degrade 1,2,4-trichlorobenzene was separated, and its degradation mechanism to 1,2,4-trichlorobenzene was studied. At the same time, the congener trace quantity organic pollutants could be biodegraded. Biofilm after domestication can effectively degrade a certain concentration range of three trichlorobenzenes and the removal effect of HRT = 7 d was better than the removal effect of HRT = 5 d. It is evident that the trace quantity organic pollutants of 1,2,4-trichlorobenzene in the source water quality from Meiliang Bay in Taihu Lake can be well degraded by enriched microbes on the artificial media.
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Boller, M. "Removal of Organic Matter by Physico-Chemical Mechanisms in Wastewater Treatment Plants". Water Science and Technology 27, n.º 11 (1 de junho de 1993): 167–83. http://dx.doi.org/10.2166/wst.1993.0275.
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Solids separation, adsorption onto participates and volatilization are the main physico-chemical mechanisms responsible for the removal of organic matter in wastewater treatment plants. In addition, solids separation as well as adsorption performance may be enhanced by chemical flocculation/precipitation with hydrolyzing metal salts. With the help of particle size distributions and other characteristics of the particulates at different treatment stages, more insight can be gained into the interactions between paniculate properties and solids separation performance. Significant removal of trace organics is achieved by adsorption onto paniculate surfaces and stripping in aeration tanks. Examples illustrate the adsorption of the relatively large quantities of substances contained in detergents and reveal the effect on water and sludge quality. Octanol/water partition coefficients of trace organics may be used together with oxygen transfer characteristics to determine the potential of volatilization into the air. The effect of flocculants on paniculate and dissolved organics removal in wastewater treatment is illustrated when Fe-salts are dosed to raw sewage, to the biological stage or to tertiary filters.
Teses / dissertações sobre o assunto "Trace organic removal"
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Banasiak, Laura Joan. "Removal of inorganic and trace organic contaminants by electrodialysis". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3998.
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With the continual concern over the presence of naturally occurring and anthropogenic inorganic and trace organic contaminants in the aquatic environment there is a growing need for the implementation of innovative treatment processes for the elimination of these contaminants from natural waters and wastewater effluents. While conventional treatment methods are ineffective in the removal of emerging contaminants such as steroidal hormones and pesticides, membrane technology, including electrodialysis (ED), has been highlighted as a potential treatment option. However, the clear lack of fundamental understanding of the behaviour of contaminants in ED is a current limitation for its extensive utilisation and is a critical issue that needs to be addressed. ED processing potentialities have not been fully exploited and more research is needed to account for all the key parameters such as contaminant physicochemical properties, solution chemistry and the presence of organic matter. The purpose of this study was to elucidate the mechanisms of inorganic and trace organic contaminant removal by ED. The inorganic contaminants fluoride, nitrate and boron were selected due to their ubiquitous nature in the environment and public health concerns resulting from longterm exposure. The hydrated radius and strength of hydration shells played a significant role in ionic transport, whereby nitrate with a smaller hydrated radius was removed more effectively (94.1 %) than fluoride (68.3 %) with a larger hydrated radius. While fluoride and nitrate removal was pH independent, the pH dependent speciation of boron enhanced its removal with increasing pH. Territorial binding and/or complexation of the inorganics with organic matter enhanced removal. The removal of a range of trace inorganics (e.g. arsenic, calcium, magnesium, uranium) from a brackish groundwater from a remote Australian community was investigated. Undissociated inorganics were not transported through the membranes, whereas dissociated inorganics were due to electrostatic attraction. At acidic-neutral conditions ionic transport was the dominant removal mechanism. At neutral to alkaline conditions insoluble carbonate species precipitated and deposited as a membrane scaling layer (60 μm). This has serious implications for the long-term practical applicability of ED to treat real waters as scaling increased ED stack resistance (pH 3: 27.5 4, pH 11: 50 4) and decreased total dissolved solids removal (pH 3: 99 %, pH 11: 89.5 %). While the treatment of trace organics by other membrane processes has been widely studied, their fate in ED and interaction with ED membranes is relatively unknown. Trace contaminant-membrane interaction studies were undertaken to quantify the partitioning of trace organics; namely steroidal hormones and the pesticide endosulfan, to ED membranes by measuring membrane-water partition coefficients (log KM). The extremely high sorption capacity of the membranes was attributed to hydrogen bonding between the trace organic and membrane functional groups. Hormone sorption during ED was influenced by solution pH and organic matter. In the case of estrone, membrane sorption decreased at pH 11 (487 μg/cm3) compared to pH 7 (591 μg/cm3) due to dissociation and membrane electrostatic repulsion .At pH 11, repulsion between dissociated estrone and HA coupled with membrane electrostatic attraction resulted in increased sorption. The findings from this study highlight that the transport of trace contaminants will depend largely on the characteristics of the membranes used in the ED process as well as the physicochemical characteristics of the contaminants, their interaction with the ED membranes and the presence of other inorganic and/or organic compounds. The knowledge gained has direct applications to current problems and uncertainties in water and wastewater treatment with regards to the fate and transport of contaminants.
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Zhang, Tianqi, e Tianqi Zhang. "Modeling Photolytic Advanced Oxidation Processes for the Removal of Trace Organic Contaminants". Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625878.
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Advanced oxidation processes (AOPs) are commonly used for the destruction of persistent trace organic contaminants (TOrCs) that survive conventional wastewater treatment processes. Three types of AOPs, UV/H2O2, sunlight photolysis and photo-Fenton are experimentally investigated and mathematically quantified to anticipate the fate of TOrCs during oxidation processes, specifically addressing the significant effect of reaction by-products and water matrix on oxidation efficiencies.
Hydrogen peroxide UV photolysis is among the most widely used AOPs for the destruction of TOrCs in waters destined for reuse. Previous kinetic models of UV/H2O2 focus on the dynamics of hydroxyl radical production and consumption, as well as the reaction of the target organic with hydroxyl radicals. In this work, we build a predictive kinetic model for the destruction of p-cresol by hydrogen peroxide photolysis based on a complete reaction mechanism that includes reactions of intermediates with hydroxyl radicals. The results show that development of a predictive kinetic model to evaluate process performance requires consideration of the complete reaction mechanism, including reactions of intermediates with hydroxyl radicals. Applying the model to an annular flow-through reactor with reflecting walls, the model mathematically demonstrates that the wall reflectivity significantly enhances the rate of conversion of the target, accounting for the UV light reflection from the reacting walls, as well as the hydrodynamics of the annular flow.
Direct and indirect sunlight photolysis is critically important in the breakdown of contaminants in effluent wastewater. The fate of a suite of TOrCs and estrogenic activity were investigated in an effluent-dependent stream. Some TOrCs, which are not sufficiently attenuated through biodegradation and soil adsorption were destructed obviously with distance of travel in the stream. Independent experiments, conducted in batch reactor with 17α-ethinylestradiol (EE2) spiked in effluent showed that attenuation of estrogenic compounds maybe due in part to indirect photolysis caused by formation of reactive species from sunlight absorption. Further investigation was conducted using selective probe compounds to characterize reactive species. And results showed that singlet oxygen generated from excited state of effluent organic matter was responsible for essentially all observed transformations of targets in the effluent in Tucson.
To mathematically quantify the photo-Fenton AOP, a kinetic model is proposed for the photolysis of Fe3+ hydroxo complexes at low pH (pH ≤ 3.0). The model incorporates elementary reactions of the Fenton-like and UV/H2O2 system. Iron speciation and photochemical parameters, including the molar absorptivities of light-absorbing species and the quantum yields of Fe3+ and FeOH2+ hydrolysis are experimentally validated. However, the predicted, time-dependent Fe2+ concentrations during Fe3+ photolysis are much lower than measured. The possible missing elements in the model could be (i) quenching of OH radicals by unknown species, or/and (ii) shielding of Fe2+ by unknown compounds at the beginning of the process.
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Chingombe, Purazen. "Removal of organic micropollutants and trace metal from water using modified activated carbons". Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7793.
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Pollution of water by herbicides and heavy metals has caused world wide concern because of the adverse effects of these pollutants on the environment, humans and wildlife. This has resulted in tighter legislation being imposed on the levels of these pollutants in drinking water. For example, the European Union (EU) has set the legislation in the drinking water Directive Admissible Concentration for a single herbicide to a maximum of 0.1 ppb. Despite the tight environmental pollution controls, isolated cases of pollutants exceeding their limits are still encountered. This would suggest that research towards the efficient and effective removal of these pollutants will be an on-going process. In this study, sorption of copper and some selected herbicides e.g. atrazine, benazolin and 2,4-dichlorophenoxyacetic acid (2,4-D) was undertaken on a conventional activated carbon and its modified series. A low level detection method was developed using High Performance Liquid Chromatography (HPLC) and this system was used to quantify the sorption capacity of the herbicides. In order to understand the sorption mechanism of the targeted pollutants, physical and chemical characterisation of the adsorbents was undertaken using a variety of techniques. These include, Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FT-IR) method, pore size distribution and surface area measurements, elemental analysis, sodium capacity determination, zeta potential and pH titration. The sorption data were presented and analysed by conventional adsorption isotherms. Sorption of the herbicides was favoured on carbon samples with least oxygen content while the uptake of copper was strongest in oxidised carbons. Kinetic experimental data were analysed by a pseudo second order model and the Boyd kinetic model. Molecular structural configurations and the physico-chemical properties of the adsorbent played a crucial role in the sorption behaviour of the herbicides.
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Dong, Bingfeng. "Application of Water/Wastewater Treatment in Trace Organic Compounds Removal and Other Industry Sectors". Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/333205.
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Wastewater reuse is fast becoming an imperative issue based on the developments in water/wastewater engineering coupled with increasing pressures on water resources. Trace organic compounds (TOrCs) that exist in water/wastewater, are a serious threat once they were released in the environment. During the past decade, there has been much progress toward understanding the occurrence, fate and toxicology of trace organic pollutants that enter the environment in treated wastewater. The objective of the first part of this research was to evaluate the combined effects of sequential anaerobic/aerobic digestion on residual TOrCs, concentrating on chemicals that are responsible for observed estrogenic/androgenic activities in biosolids. Full-scale digestion was simulated using bench-scale bioreactors in which the primary independent variables were retention time, temperature, and oxygen loading during aerobic digestion. Treatment-dependent changes in estrogenic/androgenic activity and concentrations of specific Endocrine disrupting compounds (EDCs) were measured. Results suggest that standard mesophilic anaerobic digestion increases the total estrogenic/androgenic activity of sludge while aerobic digestion was effective in the reduction of estrogenic/androgenic activity as a supplementary treatment stage. The second part of the study was focused on the fate of TOrCs and estrogenic activity in water and sediment of the Santa Cruz River, which is effluent dependent except during infrequent periods of rainfall/runoff in Tucson area. Several sampling campaigns were carried out from 2011 to 2013. Results suggest that some organic TOrCs, including those that contribute to estrogenic activity, were rapidly attenuated with distance and time of travel in the Santa Cruz River. Indirect photolysis of estrogenic compounds through the river might play an important role for the observation of estrogenic activity changes in the SCR. Hydrophobic TOrCs may accumulate in river sediments during dry weather periods. Riverbed sediment quality is periodically improved through storm-related scouring during periods of heavy rainfall and runoff. Wastewater effluent can be applied to the algal biodiesel industry based on regional water stress across the world. In the third part of the research, reclaimed wastewater was explored for this purpose, simultaneously satisfying the needs for water, macronutrients such as nitrogen and phosphorus, and micronutrients necessary for growth of microalgae. At the same time, algal growth in conventionally treated wastewater will improve water quality through the same nutrient removal processes and perhaps by lowering residual levels of trace organics that are an impediment to potable reuse. Results showed that metals levels in most municipal wastewaters are unlikely to disrupt growth, at least by metals tolerant microalgae like Nannochloropsis salina. Cells can grow without inhibition on nutrients from treated municipal wastewater or a centrate stream derived from wastewater treatment. The results also suggest while wastewater provides a suitable nutrient source for algal growth, there is simply not enough municipal wastewater available to support a meaningful biofuels industry without water recycling and nutrient recovery/reuse from spent algae. The last part of the dissertation was the application of water/wastewater treatment techniques, specifically advanced oxidation processes (AOPs) in other industrial sectors. In the integrated circuit production industry, chemical formulations used for megasonic cleaning typically contain hydroxides, peroxides and carbonates, which can affect particle removal efficiency and feature damage. The role of carbonates and ammonia in modulating the oxidation power of megasonic irradiated alkaline solutions through the scavenging of hydroxyl radicals by varying levels of carbonates, bicarbonates, ammonia and solution temperatures on net generation of hydroxyl radicals for applications in semiconductor industry was investigated in this study. The simulation of actual megasonic cleaning process was carried out at acoustic frequency of ~ 1 MHz and different power densities. Carbonate ions were better scavengers of hydroxyl radicals than bicarbonate ions. The effect of bulk solution temperature revealed that the rate of generation of hydroxyl radicals at a power density of 8 W/cm² increased with temperature from 10-30°C, which suggests an increase of transient cavitation with temperature.
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Lakshminarasimman, Meanakshisek Narasimman. "Evaluating the Fate Mechanisms of Trace Organic Compounds in Biological Nutrient Removal Treatment Systems". University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479818400753707.
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Vogel, Dirk. "The Impact of Membrane Fouling on the Removal of Trace Organic Contaminants from Wastewater by Nanofiltration". Doctoral thesis, Eigenverlag des Forums für Abfallwirtschaft und Altlasten e. V, 2017. https://tud.qucosa.de/id/qucosa%3A34037.
Texto completo da fonteResumo:
Nanofiltration (NF) is an attractive option for the treatment of wastewater e.g. municipal wastewater and landfill leachate. However, membrane fouling can be a major obstacle in the implementation of this technology. Fouling of nanofiltration membranes by hu-mic acids (HA) was investigated using bisphenol A (BPA) as an indicator chemical to dif-ferentiate between various mechanisms that may lead to a change in solute rejection. Three commercially available NF membranes were investigated and an accelerated foul-ing condition was achieved with a foulant mixture containing humic acids in an electro-lyte matrix. The effects of membrane fouling on the rejection of BPA were interpreted with respect to the membrane pore sizes and the fouling characteristics. Results report-ed here indicate that calcium concentration in the feed solution could be a major factor governing the humic acid fouling process. Moreover, a critical concentration of calcium in the feed solution was observed, at which membrane fouling was most severe. Mem-brane fouling characteristics were observed by their influence on BPA rejection. Such influence could result in either an increase or decrease in rejection of BPA by the three different membranes depending on the rejection mechanisms involved. It is hypothe-sised that these mechanisms could occur simultaneously and that the effects of each might not be easily distinguished. However, it was observed that their relative contribu-tion was largely dependent upon membrane pore size. Pore blocking, which resulted in a considerable improvement in rejection, was prominent for the more open pore size TFC-SR2 membrane. In contrast, the cake-enhanced concentration polarisation (CECP) effect was more severe for the tighter NF270 and NF90 membranes. For hydrophobic solutes such as BPA, the formation of the fouling layer could also interfere with the so-lute-membrane interaction, and therefore, exert considerable influence on the separa-tion process.
The combined impact of humic acid fouling and CaCO3 scaling on the rejection of trace organic contaminants by a commercially available nanofiltration membrane was inves-tigated in this study. Due to the presence of humic acid in the feed solution, CaCO3 scal-ing behaviour differed substantially from that of a pure CaCO3 solution. A prolonged induction period was consistently observed prior to the onset of membrane scaling. In addition, membrane scaling following humic acid fouling did not result in a complete loss of permeate flux. This is consistent with the absence of any large CaCO3 crystals. In fact, the CaCO3 crystals on the membrane surface were quite small and similar in size, which would result in a relatively porous cake layer. At the onset of CaCO3 scaling the rejection of all three trace organic contaminants started to decrease dramatically. The observed decrease in rejection of the trace organic contaminants was much more se-vere than that reported previously with a single layer of either organic or colloidal foul-ing. Such severe decrease in rejection can be attributed to the extended cake-enhanced concentration polarisation effect occurring as a result of the combination of membrane fouling and scaling. The porous CaCO3 scaling layer could lead to a substantial cake-enhanced concentration polarisation effect. In addition, the top CaCO3 scaling layer could reduce the wall shear rate within the underlying humic acid fouling layer, causing an additional concentration polarisation (CP) effect.:1 INTRODUCTION 1
1.1 Fundamentals of NF/RO 1
1.1.1 Solute transport through NF/RO membranes 2
1.1.2 Separation mechanisms 3
1.1.2.1 Steric size exclusion 3
1.1.2.2 Donnan effect 3
1.1.2.3 Electrostatic repulsion 4
1.1.2.4 Adsorption 4
1.1.3 Environmental applications of NF/RO 5
1.1.4 Drinking water treatment from groundwater and surface water sources 5
1.1.5 Water/Wastewater reclamation 7
1.2 Classification and materials of NF/RO membranes 7
1.2.1 Membrane classes 7
1.2.2 Membrane materials 8
1.2.3 Organic membrane materials 9
1.2.3.1 Polyamide membranes 9
1.2.3.2 Cellulose acetate membranes 9
1.2.4 Inorganic membrane materials 10
1.3 Removal of trace organic contaminants 11
1.3.1 Impact of membrane characteristics 14
1.3.1.1 Molecular weight cut-off/pore size 14
1.3.1.2 Surface charge 14
1.3.1.3 Hydrophobicity/hydrophilicity 15
1.3.1.4 Surface morphology 15
1.3.2 Impact of feed characteristics 17
1.3.2.1 pH value 17
1.3.2.2 Ionic strength 18
1.3.2.3 Organic matter 19
1.3.2.4 Presence of divalent ions 20
1.3.2.5 Presence of foulants 20
1.3.2.6 Temperature 20
1.3.3 Impact of solute characteristics 22
1.3.3.1 Molecular weight 22
1.3.3.2 Molecular size (length and width)/molecular volume 22
1.3.3.3 Minimum projection area/Equivalent width 23
1.3.3.4 Charge 23
1.3.3.5 Hydrophobicity/hydrophilicity 24
1.3.4 Impact of operational characteristics 25
1.3.4.1 Transmembrane pressure/permeate or transmembrane flux 25
1.3.4.2 Cross-flow velocity/recovery/concentration polarisation 25
1.3.5 Impact of fouling on rejection 26
1.3.5.1 Organic fouling 28
1.3.5.2 Colloidal fouling 30
1.3.5.3 Inorganic fouling (scaling) 31
1.3.5.4 Biological fouling 32
1.3.6 Impact of membrane cleaning on rejection 32
1.3.6.1 Changes of membrane morphology due to cleaning 32
1.3.6.2 Impact on rejection of TrOCs due to cleaning 33
1.3.7 Validation at pilot and full scale systems 35
2 MEMBRANE FOULING IN THE NANOFILTRATION OF LANDFILL LEACHATE AND ITS IMPACT ON TRACE CONTAMINANT REMOVAL 37
2.1 Introduction 37
2.2 Materials and Methods 40
2.2.1 Analytical reagents and chemicals 40
2.2.2 Nanofiltration membrane 40
2.2.3 Membrane filtration set-up and protocol 41
2.2.4 Analytical technique 42
2.3 Results and discussion 42
2.3.1 Landfill leachate characterisation 42
2.3.2 Physico-chemical properties of bisphenol A 43
2.3.3 Influence of the calcium concentration on the flux 44
2.3.4 Influence of fouling on the rejection of organic contaminants 46
2.4 Conclusions 48
3 CHARACTERISING HUMIC ACID FOULING OF NANOFILTRATION MEMBRANES USING BISPHENOL A AS A MOLECULAR INDICATOR 50
3.1 Introduction 50
3.2 Materials and methods 52
3.2.1 Model NF membranes and membrane characterisation 52
3.2.2 Model trace organic contaminant 52
3.2.3 Organic foulant 53
3.2.4 Membrane filtration set-up 54
3.2.5 Filtration protocol 55
3.2.6 Analytical technique 56
3.3 Results and discussions 56
3.3.1 Membrane characteristics 56
3.3.2 Membrane fouling behaviour 58
3.3.3 Change of membrane hydrophobicity 61
3.3.4 Effects of organic fouling on the nanofiltration of BPA 63
3.3.5 Effects of organic fouling on rejection: the mechanisms 65
3.4 Conclusions 67
4 EFFECTS OF FOULING AND SCALING ON THE REJECTION OF TRACE ORGANIC CONTAMINANTS BY A NANOFILTRATION MEMBRANE: THE ROLE OF CAKE-ENHANCED CONCENTRATION POLARISATION 69
4.1 Introduction 69
4.2 Materials and methods 71
4.2.1 Nanofiltration membrane 71
4.2.2 Chemicals and reagents 71
4.2.3 Crossflow membrane filtration system 72
4.2.4 Experimental protocol 73
4.2.5 SEM-EDS analysis 74
4.2.6 Analytical methods 75
4.3 Results and discussion 75
4.3.1 Membrane characteristics 75
4.3.2 Membrane fouling and scaling development 76
4.3.3 Effects of fouling/scaling on the membrane rejection behaviour 79
4.3.4 Cake-enhanced concentration polarisation 85
4.4 Conclusions 87
5 SUMMARY AND CONCLUSIONS 88
6 REFERENCES 94
7 ACKNOWLEDGEMENTS 112
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Khunjar, Wendell O'Neil. "Elucidating Factors that Impact the Removal of Organic Microconstituents by Ammonia Oxidizing and Heterotrophic Bacteria". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/77303.
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Although wastewater treatment plants are a line of defense in minimizing indiscriminate output of microconstituents to natural waters, we do not possess a fundamental understanding of the mechanisms involved in microconstituent removal during wastewater treatment. With this in mind, experiments were designed to investigate the factors that can influence the fate of four microconstituents, carbamazepine (CBZ), 17alpha-ethinylestradiol (EE2), iopromide (IOP), and trimethoprim (TMP), during biological suspended culture treatment. Specifically, the role that various ecological members of biological treatment systems play in biotransforming these compounds was evaluated.
Sorption assays were performed with inactivated biomass samples (ammonia oxidizing bacteria (AOB), laboratory enriched heterotrophic cultures free of active nitrifiers with low (Ox⁻) or high (Ox⁺) oxygenase activity, and a nitrifying activated sludge (NAS) from a full-scale wastewater treatment plant) to determine whether partitioning dictates removal of individual microconstituents. No microconstituents sorbed to the AOB culture. Neither CBZ nor IOP sorbed to Ox⁻, Ox⁺ and NAS cultures; however, EE2 and TMP sorbed to the Ox⁻, Ox⁺ and NAS biomass. Sorption was positively influenced by the presence of exopolymeric substances (EPS) associated with the cultures. The protein content of EPS affected EE2 and TMP sorption more appreciably than the polysaccharide content of EPS.
Further experiments were performed to investigate microconstituent biodegradation by AOBs, Ox⁻ and Ox⁺ cultures. The influence of growth state and oxygenase activity on biotransformation by each culture was also evaluated. Results indicate that EE2 was the only microconstituent that was amenable to biotransformation by batch cultured AOB and heterotrophic cultures. EE2 was biotransformed but not mineralized by AOB chemostat and batch cultures. TMP was not transformed by AOB batch or chemostat cultures; however both EE2 and TMP were transformed by Ox⁻ and Ox⁺ chemostat cultures. Radiolabeled studies showed that EE2 was mineralized by this culture. Kinetically, AOBs dominated EE2 transformation to monohydroxylated metabolites; however, both Ox⁻ and Ox⁺ cultures further degraded and mineralized EE2 and metabolites generated by AOBs. These results indicate that biotransformation of EE2 by NAS may be limited by heterotrophic activity whereas TMP fate may be a function of heterotrophic activity only. Oxygenase activity did not limit EE2 or TMP biotransformation in chemostat cultures.
Subsequent experiments that were performed to identify the factors that influence heterotrophic degradation of EE2 and TMP indicated that the presence of readily biodegradable substrates slows EE2 and TMP biotransformation. The impact of slowly biodegradable substrates like EPS on EE2 and TMP degradation was unclear. These results suggest that EE2 and TMP are most amenable to biodegradation in bioreactors where endogenous conditions dominate.Ph. D.
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Cheng, Long, e Long Cheng. "Effectiveness of Engineered and Natural Wastewater Treatment Processes for the Removal of Trace Organics in Water Reuse". Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624475.
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Due to their potential health impact on human beings and ecosystems, persistent trace organic compounds (TOrCs) have aroused concern from both the public and professionals. In particular, the discharge of pharmaceuticals, endocrine disrupters, disinfection byproducts and other TOrCs from wastewater treatment plants into the environment is an area of extensive current research. This work studies the fate and treatments of TOrCs, with emphases on advanced oxidation processes (AOPs).
This work presents predicted removal efficiencies of a variety of engineered and natural processes for 55 frequently encountered TOrCs in treated wastewater, based on previously reported data and using existing predictive models. Correlations between physicochemical and biological properties of TOrCs and treatment performance were explored. Removal of TOrCs in all processes investigated in this study was found to be sensitive to matrix effects. Heuristic guidelines for selection of sequenced treatment processes for TOrCs management were established.
A field reconnaissance of natural process of TOrCs was conducted by analyzing the occurrence and fate of a suite of TOrCs, as well as estrogenic activity in water and sediments in the Santa Cruz River, an effluent-dependent stream in Tucson, Arizona. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. TOrCs that have low biodegradability and low octanolwater partitioning coefficients were less removed. Results of independent experiments indicated potential indirect photodegradation of estrogenic compound by reactive species generated from photolysis of effluent organic matter.
Utilizing advanced oxidation processes (AOPs) as tertiary water and wastewater treatment is an option to prevent discharge of TOrCs into the environment. Compared to conventional AOPs, the ability of generating hydroxyl radicals (•OH) without additional doses of hydrogen peroxide (H2O2) or ozone makes ultraviolet (UV) photolysis of ferric hydroxo complexes a novel AOP, especially in acidic environments. A Fe(III)/UV254 kinetic model, which combines Fenton-like mechanism, and photolyses of Fe3+, FeOH2+ and H2O2 was proposed and experimentally validated to predict Fenton-like and H2O2 direct UV254 photolysis scenarios, individually. Nevertheless, the model underestimated the ferrous ion development during Fe(III)/UV254 photolysis, perhaps due to the overprediction of the oxidation of Fe2+ by •OH.
The UV/H2O2 AOP was also studied in this work. A predictive kinetic model was developed to evaluate process efficiency of oxidation of p-cresol by UV/H2O2 photolysis based on a complete reaction mechanism, including reactions of intermediates with •OH. Results of this study highlight the significance of consideration of radical scavenging effects by the byproducts from oxidation of organic matter in model prediction performance.
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Rodriguez-Gonzalez, Laura C. "Advanced Treatment Technologies for Mitigation of Nitrogen and Off-flavor Compounds in Onsite Wastewater Treatment and Recirculating Aquaculture Systems". Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6941.
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Non-point sources (NPS) of pollution are non-discernable, diffuse sources of pollution that are often difficult to localize and in turn mitigate. NPS can include stormwater runoff, agricultural/aquaculture wastes and wastes from small decentralized wastewater treatment systems, such as conventional septic systems. The mitigation of these NPS is imperative to reduce their potential detrimental effects on the water environment. This dissertation addresses novel treatment technologies for the mitigation of nutrients, particularly nitrogen, in Recirculating Aquaculture Systems (RAS) and onsite wastewater treatment systems (OWTS). The removal of trace organics limiting RAS production and water reuse were also investigated.
The first question this dissertation addressed is: Can the application of a UV-TiO2 reactor reduce the concentration of off-flavor compounds in RAS? In the UV-TiO2 reactor, spray-coated TiO2 plates were placed in an aluminum reactor and exposed to UV light. The process was applied in both a full-scale sturgeon RAS and a bench-scale RAS for the degradation of Geosmin (GSM) and 2-methylisoborneol (MIB). Improved performance on the removal of GSM and MIB was observed when the UV-TiO2 was applied as a batch reactor since it allowed for a longer treatment time without the effect of constant production of the compounds in the biological treatment processes. Treatment performance of UV-TiO2 was affected by GSM and MIB concentrations and dissolved oxygen. No harmful effects were observed on other water quality parameters when the UV-TiO2 reactor was operated as a batch or side stream process.
The second question this dissertation addressed is: Does the application of Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) in RAS improve nutrient and off-flavor compound removal when compared to conventional heterotrophic denitrification? T-SHAD combines tire mulch as an adsorbent and sulfur oxidizing denitrification for the removal of NO3--N from the aquaculture waters. Adsorption studies showed the tire has significant adsorption capacity for the off-flavor compounds GSM and MIB but can be limited by contact time and, possibly, the presence of competing organic matter in RAS. The application of T-SHAD as an effluent polishing step in RAS with a high empty bed contact time (EBCT) of 720 min removed 96.6% of NO3--N and 69.6% of GSM. The application of T-SHAD within RAS as denitrification side treatment for NO3--N removal resulted in lower EBCT (185 min) that limited NO3--N removal to 21% and showed no significant removal of off-flavor compounds. The comparison between T-SHAD and a molasses fed heterotrophic upflow packed bed reactor (UPBR), showed no significant differences in N species concentrations as well as off-flavor compound removal. However, high production of SO42- resulted from sulfur oxidizing denitrification (SOD) processes was noted.
Hybrid Adsorption and Biological Treatment Systems (HABiTS), is composed of two biofilters in series employing ion exchange (IX) and nitrification for removal of NH4+ and tire scrap coupled with sulfur chips and oyster shells for both adsorption and SOD of NO3-. The third question addressed in this dissertation is: What IX/adsorption media best balances both ammonium removal and cost effectiveness for application in OWTS? Adsorption isotherms performed with different media materials showed that the zeolite material, clinoptilolite, was the best medium for the nitrification stage of HABiTS due to its high IX capacity for NH4+and cost. An adsorption capacity of 11.69 mg g-1 NH4+-N when in competition with other cations present in septic tank effluents was determined by the IX model fit to the data.
The cost of clinoptilolite is significantly higher than the other media materials tested. However, the high adsorption capacity would allow for low dosages that can be combined with non-adsorptive material reducing overall costs.
The fourth question this dissertation addressed is: How is the BNR process within HABiTS affected by IX? Results from side-by-side biofilter studies with HABiTS and a conventional nitrification/denitrification biofilter showed that the combined IX and nitrification in HABiTS can allow for faster startup, sustain variable loading, and achieve over 80% removal of NH4+ at a hydraulic loading rate of 0.34 m3 m-2-d-1 when compared to the conventional biofilter with 73% removal. Under lower loading rates the biological treatment was enhanced and dominated the NH4+ removal processes in both columns. The addition of a denitrification stage decreased Total Inorganic Nitrogen (TIN) by 53.54% and 40.97%, for the HABiTS treatment and the control treatment, respectively, under loading rates of 0.21 m3 m-2-d-1. Further decrease of NH4+-N loading rates results in high desorption of exchanged NH4+ in the clinoptilolite, resulting in lower TIN removal efficiencies (28.7%) when compared to the conventional control treatment (62%).
The final question addressed in this dissertation is: Does the proposed hybrid system enhance the removal of TIN in OWTS under transient loading conditions? Further studies with HABiTS and the conventional biofilter were performed to determine N removal performance on an hourly basis. It was found that the performance of HABiTS varies with daily and hourly loads, particularly when recovering from periods of very low loading to high loadings and vice versa. If recovering from low loading periods, IX is observed for HABiTS and the biofilter outperforms the conventional treatment in overall TIN removal. However, recovery from a high loading period results in release of NH4+-N stored in the clinoptilolite and increased production of NO3--N that could affect the performance of the denitrification stage.
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Hermes, Nina [Verfasser], Wolfgang [Gutachter] Imhof e Thomas A. [Gutachter] Ternes. "Trace organic chemicals in the water cycle : Occurrence in wastewater treatment plants and removal by biological and chemical treatment / Nina Hermes ; Gutachter: Wolfgang Imhof, Thomas A. Ternes". Koblenz, 2021. http://d-nb.info/1227927800/34.
Texto completo da fonteLivros sobre o assunto "Trace organic removal"
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Gupta, S. K. Sen. Trace organic removal by photochemical oxidation. Chalk River, Ont: Chalk River Laboratories, 1995.
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Liška, Igor. Theoretical aspects of the use of solid phase extraction in analysis of trace organic contaminant in water. Bratislava: Water Research Institute, 1994.
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Gupta, Supriya Kumar Sen. Trace organic removal by photochemical oxidation =: Elimination des substances organiques à l'état de trace par oxydation photochimique. Chalk River, Ont: Waste Processing Technology, Chalk River Laboratories, 1995.
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Hiler, G. V. Liquid-liquid extraction of trace level pesticides from process streams. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1985.
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Hiler, G. V. Liquid-liquid extraction of trace level pesticides from process streams. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1985.
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Hiler, G. V. Liquid-liquid extraction of trace level pesticides from process streams. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1985.
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Hiler, G. V. Liquid-liquid extraction of trace level pesticides from process streams. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1985.
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Hiler, G. V. Liquid-liquid extraction of trace level pesticides from process streams. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1985.
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Drewes, Jörg E. Development of surrogates to determine the efficacy of groundwater recharge systems for the removal of trace organic chemicals. Alexandria, Va: WateReuse Research Foundation, 2011.
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Sheryl, Watkins, ed. Controlling volatile organic compound emissions from industrial wastewater. Park Ridge, N.J., U.S.A: Noyes Data Corp., 1990.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Trace organic removal"
1
Xie, Ming, Long D. Nghiem, Tao He e William E. Price. "Removal of Emerging Trace Organic Chemicals by Forward Osmosis". In Forward Osmosis, 363–94. Reston, VA: American Society of Civil Engineers, 2015. http://dx.doi.org/10.1061/9780784414071.ch16.
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Hai, Faisal I., Luong N. Nguyen, Long D. Nghiem, Bao-Qiang Liao, Ismail Koyuncu e William E. Price. "Trace Organic Contaminants Removal by Combined Processes for Wastewater Reuse". In The Handbook of Environmental Chemistry, 39–77. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/698_2014_318.
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Hai, Faisal I., Abdulhakeem Alturki, Luong N. Nguyen, William E. Price e Long D. Nghiem. "Removal of Trace Organic Contaminants by Integrated Membrane Processes for Water Reuse Applications". In Green Technologies for Sustainable Water Management, 533–78. Reston, VA: American Society of Civil Engineers, 2016. http://dx.doi.org/10.1061/9780784414422.ch15.
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Bosch-Roig, Pilar, e Patricia Sanmartín. "Bioremoval of Graffiti in the Context of Current Biocleaning Research". In Microorganisms in the Deterioration and Preservation of Cultural Heritage, 175–97. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69411-1_8.
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AbstractSome microorganisms can be used as bioremediation agents, in biocleaning treatments, to remove undesired sulphates, nitrates and organic matter from cultural heritage surfaces. Graffiti materials (mainly spray paints) are now included in the list of materials that can be biocleaned, with studies on this topic being initiated just over 5 years ago. Research on the bioremoval of graffiti is continuing and on a promising track. This chapter reports a critical analysis of studies of the bioremoval of graffiti carried out in recent years, which are compared with similar studies of the removal of salts (mainly nitrates and sulphates) and organic matter conducted in the last thirty years. Likewise, the present challenges and ways of overcoming them are addressed towards developing a complete protocol for the use of bioremediation to remove graffiti, with particular emphasis on the use of the method for cleaning facades and buildings.
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"Removal of emerging trace organic contaminants (TrOC) by MBR". In Membrane Biological Reactors, 413–68. IWA Publishing, 2019. http://dx.doi.org/10.2166/9781780409177_0413.
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Ur Rehman, Tanzil, Luqman Ali Shah, Noor Saeed Khattak, Abbas Khan, Noor Rehman e Sultan Alam. "Superabsorbent Hydrogels for Heavy Metal Removal". In Trace Metals in the Environment - New Approaches and Recent Advances. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.89350.
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The superabsorbent hydrogels (SAHs) are 3D polymer networks having hydrophilic nature, which can swell, absorb, and hold incredible amount of water in aqueous medium showing better sorption ability. The sorption ability enables SAH to absorb organic pollutants, dyes, and heavy metal ions (HMI) from wastewater. Therefore, SAHs have recently got considerable interest from the researchers to be used for wastewater treatment. In order to know the swelling property and to understand the wastewater treatment in general and heavy metal ion removal from industrial effluent in particular, this chapter describes the removal of heavy metal ions from wastewater in details. Thus this chapter will enable us to understand the theoretical and experimental part regarding the removal of heavy metal ions by SAH from wastewater. It also highlights the parameters of adsorption process such as effect of initial concentration of heavy metal ions, effect of external stimuli (pH), effect of temperature on the removal of heavy metal ions, and dosage studies. The synthesis of SAH and its use for removal of heavy metal ions from wastewater as well as recycling, selectivity, and effectiveness are also discussed in detail.
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Taber, Douglass F. "Functional Group Protection". In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0014.
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Bekington Myrboh of North-Eastern Hill University reported (Tetrahedron Lett. 2010, 51, 2862) a convenient procedure for the oxidative removal of a 1,3-oxathiolane 1 or a 1,3-dithiolane. Sang-Gyeong Lee and Yong-Jin Yoon of Gyeongsang National University developed (J. Org. Chem. 2010, 75, 484) the pyridazin-3(2H )-one 4 for the microwave-mediated deprotection of an oxime 3. Dario M. Bassani of Université Bordeaux 1 and John S. Snaith of the University of Birmingham devised (J. Org. Chem. 2010, 75, 4648) a procedure for the facile preparation of esters such as 6. Brief photolysis (350 nm) returned the parent carboxylic acid 7. Craig M. Williams of the University of Queensland prepared (Tetrahedron Lett. 2010, 51, 1158) the trithioorthoester 8 by iterative opening of epichlorohydrin. He found that the keto ester 9 could be efficiently released by Hg-mediated hydrolysis. Masatoshi Mihara of the Osaka Municipal Technical Research Institute established (Synlett 2010, 253) that even very congested alcohols such as 10 could be acetylated by acetic anhydride containing a trace of FeCl3. Colleen N. Scott, now at Southern Illinois University, developed (J. Org. Chem. 2010, 75, 253) a convenient procedure for the preparation of the hydridosilane 13, which on Mn catalysis added the alcohol 12 to make the unsymmetrical bisalkoxysilane 14. Sabine Berteina-Raboin of the Université d’Orléans found (Tetrahedron Lett. 2010, 51, 2115) that NaBH4 in EtOH cleanly removed the chloroacetates from 15. Both other esters and silyl ethers were stable under these conditions. Ram S. Mohan of Illinois Wesleyan University established (Tetrahedron Lett. 2010, 51, 1056) that Fe(III) tosylate in methanol selectively removed the alkyl silyl ether from 17 without affecting the aryl silyl ether. Alakananda Hajra and Adinath Majee of Visva-Bharati University effected (Tetrahedron Lett. 2010, 51, 2896) formylation of an amine 19 by heating with commercial 85% formic acid as the solvent in a sealed tube at 80°C. Although both primary and secondary amines could be effi ciently formylated, the primary amines were much more reactive. Doo Ok Jang of Yonsei University found (Tetrahedron Lett. 2010, 51, 683) that the conveniently handled CF3CCO2H (the acid chloride is a gas) could be activated in situ to selectively convert 22 into 24.
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Evans, Hugh L. "Cognitive Complications of Mercury Exposure". In Cognitive and Behavioral Abnormalities of Pediatric Diseases. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195342680.003.0072.
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Mercury (Hg) is a nonessential metal that has been used in a variety of industrial procedures and pharmaceutical preparations over centuries, resulting in hot spots of environmental contamination and unwanted toxicity in people who were occupationally exposed or were treated with mercury compounds (Clarkson and Magos 2006; Evans 1998). Mercury exists in three different chemical forms, each having a different profile of toxicity. The central nervous system (CNS) is considered to be the target organ for organic mercury and elemental mercury. The kidneys are considered to be the target organ of inorganic mercury. The most widespread current exposure of children is to organic mercury from ingestion of seafood, most of which is in the form of methylmercury, the most severely neurotoxic form of mercury (Clarkson and Magos 2006). Maternal consumption of seafood, although nutritionally beneficial, has been associated with elevated mercury levels in maternal blood and hair, and with deleterious outcomes in their infants. Mothers can transit mercury to their fetus through their blood supply or to their infant through maternal milk. Children also are exposed to mercury in regions where gold is mined (Bose-O’Reilly et al. 2008). Other sources of exposures have been reviewed by Clarkson and Magos (2006). Over the past two decades in the United States, mercury has been increasingly restricted by the U.S. Environmental Protection Agency, and it has been removed from consumer products (where it had been used as a fungicide). Current efforts are under way to encourage consumers to trade their mercury thermometers for newer models that do not use mercury. Mercury has no essential nutritional role, so any amount of mercury in the body can be considered undesirable. For practical purposes, since mercury is present at some level almost everywhere on Earth, the key question is at what dose or concentration in the body can mercury-induced toxicity be documented? Continuing improvements in chemical measurement has resulted in the determining of mercury in lower concentrations. This has been matched by advances in neurological measurements and statistical analyses, resulting in the extrapolation of lower “safe” levels of mercury levels in drinking water, hair, and blood.
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Roczniak, Wojciech, Magdalena Babuśka Roczniak, Elżbieta Cipora e Barbara Brodziak Dopierała. "Analysis of Occurrence of Elements in Tissues of the Knee Joint". In Trace Elements and Their Effects on Human Health and Diseases. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95418.
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The mineral structure of bones is never static, it is a living structure, reacting and adapting to load and having the ability to remodel. Skeletal cells work continuously to maintain the remodelling process therefore they are in a constant state of dynamic balance both in the sense of composition and structure, and they react to external mechanical forces. The remodelling processes that occur in the bone tissue allow for a proper functioning of this tissue, as well as for inclusion of additional elements, toxic ones included, in the remodelled bone, and they affect the metabolic processes occurring therein. This may result in disturbances in the osteoarticular system, manifested by changes in the bone tissue and within other organs. The influence of tobacco smoking on the content of strontium, lead, calcium, phosphorus, sodium and magnesium has not been confirmed. Non-smokers showed a high iron content in knee joint tissues compared to smokers. There were no statistically significant differences in the content of cadmium, nickel, copper and zinc in women and men in the studied knee joint components. With age, an increase in the content of chromium in knee joint tissues was observed, while gender, place of residence and occupational exposure had no effect.
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Sousa, Lisa. "Rebellious Women". In The Woman Who Turned Into a Jaguar, and Other Narratives of Native Women in Archives of Colonial Mexico. Stanford University Press, 2017. http://dx.doi.org/10.11126/stanford/9780804756402.003.0009.
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Chapter 9 studies women’s participation in public protests and acts of civil disobedience, including riots. It shows how threats to the integrity of the household and community, such as increased demands for tribute and labor, disputes over land and natural resources, and Spanish attempts to remove local officials from office, led men and women to seek legal redress, to protest, and at times to rebel against colonial authorities. The chapter traces women’s efforts to organize acts of resistance, such as the refusal to pay tribute, and their leadership roles in local riots. While women did not hold political office, they were aware of controversies over lands, resources, and legal suits to protect these assets. Chapter 9 argues that women’s participation in efforts to defend their homes, communities, and allies reveals a broader consciousness that has been overlooked or underestimated in previous studies.
Trabalhos de conferências sobre o assunto "Trace organic removal"
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Eckhard, F., A. J. Van Der Werf, R. Veneri, C. Lobascio e Ch Lasseur. "Removal of Organic Trace Contaminants Using a Biological Air Filter (BAF)". In International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-2471.
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Atwater, James E., e John T. Holtsnider. "Airborne Trace Organic Contaminant Removal Using Thermally Regenerable Multi-Media Layered Sorbents". In International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1991. http://dx.doi.org/10.4271/911540.
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Vu, Trinh, Highqueen Sarpomah, Michael Kamen, Tolessa Deksissa e Jiajun Xu. "Nanoparticles Infused Mesoporous Material for Water Treatment Processes". In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70475.
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In current study, a hybrid mesoporous material infused with metallic oxide nanoparticles, MCM-48 with TiO2 nanoparticles, has been developed for potential application in water treatment. Using this unique hybrid structure, it can combine the advantages of the effective pollutants removal capability of metallic oxide nanoparticles, and the strong yet high permeable structure of mesoporous material. A modified hydrothermal method has been developed to synthesize three hybrid samples with TiO2 nanoparticles of three assorted sizes (15, 50 and 300nm), and their structure have also been characterized. The synthesized samples are tested for its capability of removing organic dye and trace metals using ICP-MS. The results have shown that while all three hybrid materials have shown over 80% adsorption rate for organic dye, the sample synthesized using 300nm TiO2 nanoparticle has shown the highest adsorption rate. Similarly, the highest adsorption rate for most trace metals test here also occurs in the sample made with 300nm TiO2 nanoparticle. Coincidentally, the sample prepared with 300nm TiO2 nanoparticle has a much larger internal surface area and smaller average pore size compared to the two other samples, which may lead to the higher adsorption rate of trace metals and organic dye tested here. This study has presented a hybrid mesoporous material that can be potentially used for pollutants removal of water treatment. Future studies are still needed to fully explore this hybrid material and its capability in water treatment.
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Skoglund, Lars, e Rajen Dias. "Laser Milling Techniques for Stacked Die Package Applications". In ISTFA 2004. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.istfa2004p0369.
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Abstract Ultraviolet (UV) lasers can be used as microsurgery tools to deprocess electronic packages to expose the device and internal package features. A UV laser milling tool was characterized for various applications on multiple die stacked packages to assist in fault isolation and failure analysis. Laser milling procedures evaluated were package delayering to expose traces, trace cutting so that fails can be isolated between the die and package, wire bond exposure and cutting, multiple stacked die exposure through mold compound decapsulation and device milling. Results show excellent selectivity of the laser in removing organic material without etching copper traces at multiple layers in the organic package. Mold compound removal above the die was limited to within ~15 microns of the die surface to prevent any die damage. Mold compound decapsulation outside the die area to expose multiple layers of wire bonds for probing and inspection was developed after overcoming issues related to wire damage. In conclusion, laser milling procedures developed and evaluated show that the technique has a unique advantage in performing local package microsurgery with minimal damage or change in the global stress state of the package.
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Fellingham, Lorimar, Andrew Graham e Steven Stiff. "Characterisation and Remediation of Beryllium Waste Pits in the Southern Storage Area at Harwell". In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4861.
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The Southern Storage Area at UKAEA’s Harwell site was used from the late 1940’s through until the late 1980’s for the storage, packaging and disposal of various radioactive and chemical wastes. These included beryllium-contaminated wastes arising primarily from the decommissioning of redundant beryllium fabrication facilities. The latter were buried in five unlined, shallow trenches, each being ∼40–50 m long by 6 m wide and 3–4 m deep. An environmental assessment identified three feasible options for the future of these “Beryllium” Pits. These were full excavation with removal of their contents and surroundings, capping and long-term care and maintenance. These options were studied more extensively to select the best practicable environmental option (BPEO), which was excavation. This paper describes in detail the characterisation and remediation approaches used in identifying, planning and successfully implementing that option. It also compares the actual waste arisings in nature, form and quantities with the expectations from the characterisation investigations. At the project commencement limited information existed from records and past trial pitting on the form and contents of the pits. Thus much more extensive characterisation was necessary to determine their dimensions, identify waste types, volumes and disposal routes and quantify potential hazards for any excavations. The characterisation programme involved planning, setting up a site infrastructure, site clearance, non-intrusive surveying and intrusive characterisation by coring. The pit areas and their immediate surroundings were monitored for radiological contamination, followed by geophysical surveys using magnetometry and ground penetrating radar. Primary and secondary containment systems were then constructed over the pits before coring, sampling and analysis on a predefined grid. There was significant beryllium contamination in all pits with some limited contamination by heavy metals, including mercury, and radionuclides. There were also trace levels of volatile organic solvents. These data provided the basis for planning the remediation. The remediation was successfully undertaken to achieve as a minimum a set of remediation targets for residual chemical and radioactive contamination. These targets were determined from site-specific risk assessments, best practice and waste limits. Each pit was remediated within a sealed and ventilated primary containment inside a secondary weatherproof containment building. A horizontal mining approach was adopted to pit excavation with a small excavator initially placed in a launch pit constructed immediately outside the pit. The excavator worked along the pit removing thin layers of waste from an inclined face ahead of it. The waste was placed into bags on trolleys on rails. It was removed via a posting port. After removal of all of the contents and hazardous materials, the containment was removed. Any further excavation required to meet the remediation targets was undertaken in bulk in the open. After verification sampling the remediation was completed by inserting a low permeability barrier of clay and a bentonite geotextile into the base of the pit and backfilling with compacted clean soil. The remediation was completed with successful achievement of all remediation criteria and minimal impacts on the operators, public and environment.
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Li, Ran, e Jiyang Yu. "Development of PCCSAP-3D Code for Passive Containment: Models of Noncondensable Gases, Aerosols and Fission Products". In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15606.
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PCCSAC-3D is a code originally developed for AC600 containment thermo-hydraulic analysis. Its validated capabilities include simulating the behaviors of steam-air mixture and liquid water under the unique conditions of an AC600/AP1000 containment after a DBA. The film-tracking model applied gives it the ability to simulate the liquid film both outside and inside the steel containment. Refined with some new models, the new version of the code, named PCCSAP-3D, can cover hydrogen behavior, fission products behavior (in the form of gas and aerosol) and iodine behavior. In the module of noncondensable gas, diffusion of up to 11 species are taken into consideration. A user-definable recombiner/ignitor model is developed to accommodate different types of hydrogen recombiners and ignitors. Given the source term as a boundary condition, the fission products model would be able to track up to 64 radio-isotopes after a LOCA. The leakage and spontaneous decay is accounted for all of these nuclides. Besides, the noble gases, gaseous iodine and fission product aerosols are treated separately. There is no removal mechanism of noble gases. Whereas removal mechanisms of radio-aerosols considered include spray, gravitational sedimentation, diffusio-phoresis and thermo-phoresis. A simple model for gaseous iodine comprises organic iodine and elemental iodine, in which the effects of spray and liquid adsorption are treated integrally. To evaluate the radioactivity consequences of a certain accident, a radioactivity calculation model is brought out to convert the molar concentration or mass concentration of radioactive material into radioactivity concentration. The new version of PCCSAP-3D code with models aforementioned is preliminarily validated by comparing the simulation results with safety analysis results reported in AP1000 Design Control Document. The accident scenario is set as a design basic LOCA with core melt.
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Wan, William, Laura Hansen e Rudolph L. Gleason. "A 3-D Constrained Mixture Model for Vascular Growth and Remodeling". In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206778.
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It is known that arteries adapt and remodel to changes in their loading conditions. Evolution of mechanical properties of blood vessels is associated with numerous chronic and acute conditions such as hypertension and coronary thrombosis. In addition, treatments such as bypass surgery create loading conditions not seen in normal arteries. Blood vessels used in coronary bypass grafts experience abnormal loading conditions in both circumferential and axial directions. Blood vessels remodel by altering structural components to restore homeostatic values of stress. Such changes may include smooth muscle cell proliferation, migration and collagen synthesis, degradation, and remodeling. While biaxial mechanical tests and organ culture experiments provide values for global variables such as mean stresses and total thickness, mathematical models can help describe local mechanical properties at locations throughout the vessel wall. Experimental observations suggest that constituents of arteries turnover at different rates; thus, it is important that models are able to track individual constituents of the artery separately. Here, we present a 3D constrained mixture model for growth and remodeling of arteries exposed to large changes in flow, pressure, and axial stretch -induced.
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Santhanakrishnan, Arvind, Trent Nestle, Brian Moore, Ajit P. Yoganathan e Matthew L. Paden. "Characterization of a Low Extracorporeal Volume, High Accuracy Pediatric Continuous Renal Replacement Therapy Device". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80210.
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The incidence of acute kidney injury (AKI) is commonly seen in critically ill children, the origins of which may be traced to a wide range of conditions such as inborn errors of metabolism, sepsis, congenital heart defects, bone marrow and organ transplantation, and to a lesser extent from multiple organ dysfunction syndrome (MODS) [1]. It is vital to provide a form of fluid and electrolyte clearance in these patients until native renal function improves. Nearly 3,600 critically ill children per year with acute kidney injury receive life-saving continuous renal replacement therapy (CRRT) in the United States. However, there is no CRRT device approved by the Food and Drug Administration for use in pediatric patients. Thus, clinicians unsafely adapt adult CRRT devices for use in the pediatric patients due to lack of safer alternatives. Complications observed with using adult adapted CRRT devices in children include hypotension, hemorrhage, thrombosis, temperature instability, inaccurate fluid balance between ultrafiltrate (UF) removed from and replacement fluid (RF) delivered to the patient, electrolyte disorders, and alteration of drug clearance. This research addresses this unmet clinical need through the design, mechanical and biological characterization of a pediatric specific Kidney Injury and Dysfunction Support (KIDS) CRRT device that provides high accuracy in fluid balance, reduces extracorporeal blood volume, and eliminates other problems associated with using adapted adult CRRT devices in children.
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Kim, Bumjick, e Reginald E. Mitchell. "Development of a System for the Study of Solid Fuel Conversion Under Supercritical Water Conditions". In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89752.
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Due to its low cost and abundance, a large amount of coal and biomass is still being used to generate electricity throughout the world. Given that these solid fuels are here to stay for the foreseeable future, the problem of their environmental impact in terms of their emission of CO2 and harmful gas streams will remain unless solutions to it can be found. Supercritical water (SCW) is an attractive medium for power generation because of its special characteristics. Organic compounds extracted from coal and biomass hydrolyze, and they are completely miscible in SCW. In contrast, sulfur, chlorine and many trace elements in coal are oxidized and form insoluble salts in SCW, which precipitate and can be removed. The coal/biomass-to-electricity scheme takes advantage of these characteristics of SCW in using it as a reaction medium. A description of the experimental facility to conduct experiments for pulverized coal and biomass conversion under SCW conditions (P>218 atm and T>647 K) is provided. The facility includes high-pressure water pumps, pulse-dampening accumulators, a water preheater, an oxygen booster, a SCW gasification reactor, and a reaction quenching cooler. This work presents the entire coal/biomass conversion system, built and assembled, which permits the acquisition of data needed to determine the rate coefficients for reactions that are suitable for SCW conditions. The focus of the facility is a flow reactor that can be pressurized up to 340 atm at temperatures up to 750 K. The continuous flow reactor is 15 meters long, sufficient for residence times as long as 15 minutes when the total mass flow rate (slurry plus SCW flow rates) is 20 grams/min. The residence time in the reactor is varied by controlling the solids content of the slurry and the flow rate of the water supplied. The feed water is pressurized and preheated to the test conditions before the solids slurry and any oxygen are admitted. Oxygen is added so that the heat release from partial oxidation of the solids can supply energy for autothermal gasification. The facility developed is in operation to collect data sets for the characterization of conversion mechanism.
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Causse, Jeremy, Cyril Roussignol, Jean-Franc¸ois Vale´ry e Jean-Charles Hamel. "New Degreasing Formulations for the Decontamination of Solid Substrates, Consistent With Concentration and Vitrification Process of the Final Wastes". In ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2011. http://dx.doi.org/10.1115/icem2011-59166.
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Decontamination facilities use various techniques to decontaminate solid substrates. The aim of these facilities is either to recover the substrate for a future second life, or to sufficiently lower the radioactivity level in order to reduce the final volume of high activity waste. One of these techniques remains in aqueous bathes under ultrasonic agitation. This technique is very suitable for the decontamination of small metallic pieces. Most of those pieces are covered with various greases or organic oils very resistant to classical aqueous washes. Thus, this oily layer contains some unfixed radionuclides that must be removed to reach the aimed decontamination factor. This urged decontamination facilities operating staff to consider additive molecules necessary to render aqueous washes consistent with such a contamination. These molecules, namely surfactants, act on the liquid surface to increase affinity between aqueous and oily phases. The surfactant formulations commonly used in French decontamination facilities are standard industrial formulations (F1, F2). Those formulations are generally designed by international manufacturers to be consistent with several applications. Thus, there isn’t any specific formulation fitted to nuclear applications. Today, according to potential modification of the final wastes conditioning matrix (for instance glass matrix instead of bitumen matrix), this standard formulations use could move to the use of some dedicated formulations for nuclear use. The glass matrix and related effluents concentration process required effluents with controlled chemical composition with regard to the presence of radionuclides. However, the composition of the industrial formulations used until today are not precisely known (according to trade secret), and sometimes can contain molecules unfitted to the final waste vitrification process. For instance, some sodium silicates are used to bring basic properties to the surfactant formulations whereas this kind of compounds is quite inappropriate to the concentration process (possible formation of gel in nitric acid with high concentration of silicates). The present study deals with the potential replacement of these industrial formulations by other ones with controlled chemical composition and concentration. Each new formulation consists of an assembly of well-known surfactants. The first stage of this study involves the degreasing power evaluation for every formulation. Solid and liquid greases detachment is assessed thanks to different techniques. For instance, the study of liquid greases detachment is achieved thanks to a CCD camera. The contact angle between the solid substrate and the grease is followed up during the degreasing step. This allows us to draw degreasing kinetics so as to compare the formulation effectiveness including industrial ones. The second stage of this work presents decontamination factor achieved during real operations with the new designed formulations. These tests were performed in an industrial decontamination facility and the efficiency of the new formulations is compared to the standard industrial ones.
Relatórios de organizações sobre o assunto "Trace organic removal"
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Lin, Xiao-Min, e Subramanian Sankaranarayanan. Ultrathin Nanoparticle Membranes to Remove Emerging Hydrophobic Trace Organic Compounds in Water with Low Applied Pressure and Energy Consumption. Office of Scientific and Technical Information (OSTI), fevereiro de 2019. http://dx.doi.org/10.2172/1502835.
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