934 resultados para water recirculating system


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Mode of access: Internet.

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Bibliography: p. 73-77.

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A bacterium (MJ-PV) previously demonstrated to degrade the cyanobacterial toxin microcystin LR, was investigated for bioremediation applications in natural water microcosms and biologically active slow sand filters. Enhanced degradation of microcystin LR was observed with inoculated (1 x 10(6) cell/mL) treatments of river water dosed with microcystin LR (> 80% degradation within 2 days) compared to uninoculated controls. Inoculation of MJ-PV at lower concentrations (1 x 10(2)-1 x 10(5)cells/mL) also demonstrated enhanced microcystin LR degradation over control treatments. Polymerase chain reactions (PCR) specifically targeting amplification of 16S rDNA of MJ-PV and the gene responsible for initial degradation of microcystin LR (mlrA) were successfully applied to monitor the presence of the bacterium in experimental trials. No amplified products indicative of an endemic MJ-PV population were observed in uninoculated treatments indicating other bacterial strains were active in degradation of microcystin LR, Pilot scale biologically active slow sand filters demonstrated degradation of microcystin LR irrespective of MJ-PV bacterial inoculation. PCR analysis detected the MJ-PV population at all locations within the sand filters where microcystin degradation was measured. Despite not observing enhanced degradation of microcystin LR in inoculated columns compared to uninoculated column, these studies demonstrate the effectiveness of a low-technology water treatment system like biologically active slow sand filters for removal of microcystins from reticulated water supplies. Crown Copyright (c) 2006 Published by Elsevier Ltd. All rights reserved.

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Molecular dynamics simulations have been used to study the phase behavior of a dipalmitoylphosphatidylcholine (DPPC)/palmitic acid (PA)/water 1:2:20 mixture in atomic detail. Starting from a random solution of DPPC and PA in water, the system adopts either a gel phase at temperatures below similar to 330 K or an inverted hexagonal phase above similar to 330 K in good agreement with experiment. It has also been possible to observe the direct transformation from a gel to an inverted hexagonal phase at elevated temperature (similar to 390 K). During this transformation, a metastable fluid lamellar intermediate is observed. Interlamellar connections or stalks form spontaneously on a nanosecond time scale and subsequently elongate, leading to the formation of an inverted hexagonal phase. This work opens the possibility of studying in detail how the formation of nonlamellar phases is affected by lipid composition and (fusion) peptides and, thus, is an important step toward understanding related biological processes, such as membrane fusion.

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In brackish groundwater desalination, high recovery ratio (of fresh water from saline feed) is desired to minimise concentrate reject. To this effect, previous studies have developed a batch reverse osmosis (RO) desalination system, DesaLink, which proposed to expand steam in a reciprocating piston cylinder and transmit the driving force through a linkage crank mechanism to pressurise batches of saline water (recirculating) in a water piston cylinder unto RO membranes. However, steam is largely disadvantaged at operation from low temperature (< 150oC) thermal sources; and organic working fluids are more viable, though, the obtainable thermal cycle efficiencies are generally low with low temperatures. Consequently, this thesis proposed to investigate the use of organic working fluid Rankine cycle (ORC) with isothermal expansion, to drive the DesaLink machine, at improved thermal efficiency from low temperature thermal sources. Following a review of the methods of achieving isothermal expansion, ‘liquid flooded expansion’ and ‘expansion chamber surface heating’ were identified as potential alternative methods. Preliminary experimental comparative analysis of variants of the heated expansion chamber technique of effecting isothermal expansion favoured a heated plain wall technique, and as such was adopted for further optimisation and development. Further, an optimised isothermal ORC engine was built and tested at < 95oC heat source temperature, with R245fa working fluid – which was selected from 16 working fluids that were analysed for isothermal operation. Upon satisfactory performance of the test engine, a larger (10 times) version was built and coupled to drive the DesaLink system. Operating the integrated ORC-RO DesaLink system, gave freshwater (approximately 500 ppm) production of about 12 litres per hour (from 4000 ppm feed water) at a recovery ratio of about 0.7 and specific energy consumption of 0.34 kWh/m3; and at a thermal efficiency of 7.7%. Theoretical models characterising the operation and performance of the integrated system was developed and utilised to access the potential field performance of the system, when powered by two different thermal energy sources – solar and industrial bakery waste heat – as case studies.

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Produced water constitutes the largest volume of waste from offshore oil and gas operations and is composed of a wide range of organic and inorganic compounds. Although treatment processes have to meet strict oil in water regulations, the definition of “oil” is a function of the analysis process and may include aliphatic hydrocarbons which have limited environmental impact due to degradability whilst ignoring problematic dissolved petroleum species. This thesis presents the partitioning behavior of oil in produced water as a function of temperature and salinity to identify compounds of environmental concern. Phenol, p-cresol, and 4-tert-butylphenol were studied because of their xenoestrogenic power; other compounds studied are polycyclic aromatic hydrocarbon PAHs which include naphthalene, fluorene, phenanthrene, and pyrene. Partitioning experiments were carried out in an Innova incubator for 48 hours, temperature was varied from 4゚C to 70゚C, and two salinity levels of 46.8‰ and 66.8‰ were studied. Results obtained showed that the dispersed oil concentration in the water reduces with settling time and equilibrium was attained at 48 h settling time. Polycyclic aromatic hydrocarbons (PAHs) partitions based on dispersed oil concentration whereas phenols are not significantly affected by dispersed oil concentration. Higher temperature favors partitioning of PAHs into the water phase. Salinity has negligible effect on partitioning pattern of phenols and PAHs studied. Simulation results obtained from the Aspen HYSYS model shows that temperature and oil droplet distribution greatly influences the efficiency of produced water treatment system.

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On DSDP Leg 84, drilling was conducted at three gas-hydrate-bearing sites on the Middle America Trench slope off Costa Rica (Site 565) and off Guatemala (Sites 568 and 570). At Site 569, on the mid-slope off Guatemala, hydrates may be present, according to the seismic profile (GUA-13), although the pore-water composition does not provide clear evidence. Sites 566 and 567, on the lower Guatemala Trench slope, appear to be free of hydrates, except in fractures of serpentinite at the bottom of Hole 566. Hydrate-bearing Sites 565, 568, and 570 show the effects of hydrate decomposition on pore-water chemistry that have been established during previous drilling at Sites 496 and 497 on the Guatemala Trench slope. These include a chlorinity decrease and d18O increase downsection. The new results, however, reveal more complex relationships between the chlorinity decrease and d18O increase than previously recognized. At Site 565, d18O values decrease in the middle section of the hole, whereas chlorinity continues to decrease from the top to near the bottom of the hole. Early diagenetic alteration of volcanic glass is suggested as a mechanism for the unexpected minimum in the O-isotope curve. Multiple fractionation by the pore-water/hydrate system is required to explain d18O-values greater than 2.7 per mil at the bottom of Hole 568, because with a fractionation factor of alpha = 1.0027, this is the maximum figure a single-stage fractionation could produce. In situ water samples from hydrate zones in most cases failed to display the elevated salinities expected for the residual pore waters not involved in hydrate formation. This is probably because the in situ sampling device still allows a systematic pressure drop sufficient to trigger hydrate decomposition in the immediate vicinity of the sample port.

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Urban areas such as megacities (those with populations greater than 10 million) are hotspots of global water use and thus face intense water management challenges. Urban areas are influenced by local interactions between human and natural systems and interact with distant systems through flows of water, food, energy, people, information, and capital. However, analyses of water sustainability and the management of water flows in urban areas are often fragmented. There is a strong need to apply integrated frameworks to systematically analyze urban water dynamics and factors that influence these dynamics. We apply the framework of telecoupling (socioeconomic and environmental interactions over distances) to analyze urban water issues, using Beijing as a demonstration megacity. Beijing exemplifies the global water sustainability challenge for urban settings. Like many other cities, Beijing has experienced drastic reductions in quantity and quality of both surface water and groundwater over the past several decades; it relies on the import of real and virtual water from sending systems to meet its demand for clean water, and releases polluted water to other systems (spillover systems). The integrative framework we present demonstrates the importance of considering socioeconomic and environmental interactions across telecoupled human and natural systems, which include not only Beijing (the water-receiving system) but also water-sending systems and spillover systems. This framework helps integrate important components of local and distant human–nature interactions and incorporates a wide range of local couplings and telecouplings that affect water dynamics, which in turn generate significant socioeconomic and environmental consequences, including feedback effects. The application of the framework to Beijing reveals many research gaps and management needs. We also provide a foundation to apply the telecoupling framework to better understand and manage water sustainability in other cities around the world.

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Pure Water, is a crucial demand of creature life. Following industrial development, extra amount of toxic metals such as chromium enters the environmental cycle through the sewage, which is considered as a serious threat for organisms. One of the modern methods of filtration and removal of contaminants in water, is applying Nano-technology. According to specific property of silicate materials, in this article we try to survey increased power in composites and various absorption in several morphologies and also synthesis of Nano-metal silicates with different morphologies as absorbent of metal toxic ions. At first, we synthesize nano zink silicate with three morphologies considering context and the purpose of this survey. 1) Nano synthesis of zink silicate hollow cavity by hydrothermal method in mixed solvent system of ethanol/glycol polyethylene. 2) Zink nano wires silicate in a water-based system by controlling the amount of sodium silicate. 3) Synthesis of nano zink silicate membrane. After synthesizing, we measured the cadmium ion absorbance by synthesized nano zink silicates. Controlling PH, is the applied absorption method. Next step, we synthesized nano zink-magnesium silicate composite in two various morphologies of nanowires and membrane by different precent of zink and magnesium, in order to optimize synthesized nano metal silicate. We used zink nitrate and magnesium nitrate and also measured cadmium absorption by synthesized nano metal silicates in the same way of PH control absorption. In the 3rd step, in order to determine the impact of the type of metal in nano metal silicate, we synthesized nano magnesium silicate and compared its absorption with nano zink silicate. Furthermore, we calculated the optimal concentration in one of synthesizes. Optimal concentration is the process which has the maximum absorption. While applying two methods of absorption in the test, finally we compared the effect of absorption method on the absorption level. Below you find further steps of synthesis: 1) Using IR, RAMAN, XRD spectroscopy to check the accuracy of synthesis. 2) Checking the dispersion of nano particles in ethanol solution by light microscope. 3) Measuring and observing particles with scanning electron microscope (SEM). 4) Using atomic absorption device for measuring the cadmium concentration in water-based solutions. The nano metal silicates were synthesized successfully. All of synthesized nano absorbents have the cadmium ion absorbency. The cadmium absorption via nano absorbents depend on various factors such as kind of metal in nano silicate and percent of metal in nano metal silicate composite. Meanwhile the absorption and PH control of medium containing the absorbent and solution would affect the cadmium absorption.

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The effects of four light intensities (0; 2.8 +/- 0.9; 5,5 +/- 1,8 e 7,8 +/- 2,5 mu mol s(-1) m(-2), about 136.5 +/- 87.5; 273 +/- 43.8 e 390 +/- 125 lux, respectively) on survival, productivity, weight gain and larval development of Macrobrachium amazonicum were investigated. Four treatments with three replicate tanks were evaluated. Newly hatched larvae were held in black tanks (80.2 +/- 0.6 larvae L(-1)) filled with 50-L-brackish water (salinity of 10), in a recirculating system. Tanks were covered with shadow cloth allowing 35% and 70% light, respectively, to reach light intensities of 2.8 +/- 0.9 and 5.5 +/- 1.8 mu mol s(-1) m(-2) at the water surface. Complete absence of light (0 mu mol s(-1) m(-2)) was obtained covering the tanks with opaque black plastic, and full-light condition used no covering (7.8 +/- 2.5 mu mol s(-1) m(-2)). Observations showed that the survival rate was not affected by light intensity. Productivity and weight gain were higher under 7.8 +/- 2.5 mu mol s(-1) m(-2) light intensity than under 0 and 2.8 +/- 0.9 1 mu mol s(-1) m(-2) intensities (P<0.05). The larval development index was similar among the treatments under the different light intensities. However, from stage VII this index was increased slightly in the treatment under 7.8 +/- 2.5 mu mol s(-1) m(-2) light intensity. In conclusion, light intensity affects larval development of M. amazonicum. Values as high as 7.8 mu mol s(-1) m(-2) (about 390 lux) improve the larval performance by enhancing development, productivity and weight gain compared to lower values.

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Estudou-se atraves de um experimento em blocos ao acaso, os efeitos de quatro niveis de nitrogenio, em diferentes condicoes de umidade, sobre os estagios de crescimento, embonecamento, formacao de graos e prdutividade do milho (Zea mays L.) e as relacoes entre a produtividade e os tres primeiros estagios. Os fatores da resposta de producaobaseados na equacao de Doorenbos e Kassam variaram acentuadamente, nao so com os diferentes estatios de crescimento, mas tambem com diferentes niveis de nitrogenio e os diferentes niveis de agua. Assim, esta equacao nao pareceu ser valida para explicar a resposta de produtividade a niveis de agua. Sugeriu-se um equacao linear modificada. Nesta equacao, a intercessao K1 e inclinacao K2 sao os fatores da resposta de producao. Estes fatores para a cultura do milho foram desenvolvidos para todos os quatro estagios de crescimento e nveis de nitrogenio. Pode-se obter uma eficiencia media do uso de agua, em termos de produtividade, de, aproximadamente, 57,5 kg/ha-cm de agua, sendo, contudo, pequeno o incremento, em face dos niveis crescentes de nitrogenio aplicado ate 120 kg/ha. Os coeficientes de cutura (Kc) calculados estao muito abaixo da estimativa da FAO, para todos os niveis de nitrogenio. Por essa razao, deve haver consideravel economica de agua se estes coeficientes forem usados em lugar da estimativa da FAO. A informacao mostradapode imediatamente ser utilizada para turno de irrigacao e para projetos de irrigacao suplementar planejado para as condicoes doe Nordeste do Brasil.

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A recirculating system and a matching management schedule for small-scale freshwater prawn larviculture were described. The system comprised a 140 L larval culture tank in line with a 43 L biofilter filled with 24 L of calcareous substrate. Both the tank and biofilter were made of black colored fiberglass in a conical-cylindrical shape. The turnover rate of the water through the system was 24 times a day; water was pumped by airlift. Results of ten larvicultures showed that the system maintained temperature, dissolved oxygen, pH, salinity, ammonium and nitrite stable and suitable to Macrobrachium rosenbergii larvae. Survival and productivity varied from 60.5 to 72.4% and 37 to 72 post-larvae/L, respectively; both were compatible with results of commercial hatcheries. Therefore, this system may be very useful for research purposes or adapted for small-scale post-larvae production.

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This manuscript reports the overall development of a Ph.D. research project during the “Mechanics and advanced engineering sciences” course at the Department of Industrial Engineering of the University of Bologna. The project is focused on the development of a combustion control system for an innovative Spark Ignited engine layout. In details, the controller is oriented to manage a prototypal engine equipped with a Port Water Injection system. The water injection technology allows an increment of combustion efficiency due to the knock mitigation effect that permits to keep the combustion phasing closer to the optimal position with respect to the traditional layout. At the beginning of the project, the effects and the possible benefits achievable by water injection have been investigated by a focused experimental campaign. Then the data obtained by combustion analysis have been processed to design a control-oriented combustion model. The model identifies the correlation between Spark Advance, combustion phasing and injected water mass, and two different strategies are presented, both based on an analytic and semi-empirical approach and therefore compatible with a real-time application. The model has been implemented in a combustion controller that manages water injection to reach the best achievable combustion efficiency while keeping knock levels under a pre-established threshold. Three different versions of the algorithm are described in detail. This controller has been designed and pre-calibrated in a software-in-the-loop environment and later an experimental validation has been performed with a rapid control prototyping approach to highlight the performance of the system on real set-up. To further make the strategy implementable on an onboard application, an estimation algorithm of combustion phasing, necessary for the controller, has been developed during the last phase of the PhD Course, based on accelerometric signals.

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To change unadapted water governing systems, and water users’ traditional conducts in line with climate change, understanding of systems’ structures and users’ behaviors is necessary. To this aim, comprehensive and pragmatic research was designed and implemented in the Urmia Lake Basin where due to the severe droughts, and human-made influences, especially through the agricultural development, the lake has been shrunken drastically. To analyze the water governance and conservation issues in the basin, an innovative framework was developed based on mathematical physics concepts and pro-environmental behavior theories. Accordingly, in system level (macro/meso), the problem of fit of the early-shaped water governing system associating with the function of “political-security” and “political-economic” factors in the basin was identified through mean-field models. Furthermore, the effect of a “political-environmental” factor, the Urmia Lake Restoration Program (ULRP), on reforming the system structure and hence its fit was assessed. The analysis results revealed that by revising the provincial boundaries (horizontal alternation) for the entity of Kurdistan province to permit that interact with the headquarter of West Azerbaijan province for its water demand-supply initiatives, the system fit can increase. Also, the constitution of the ULRP (vertical arrangement) not only could increase the structural fit of the water governing system to the basin, but also significantly could enhance the system fit through its water-saving policy. Besides, in individual level (micro), the governing factors of water conservation behavior of the major users/farmers were identified through rational and moral socio-psychological models. In rational approach, incorporating PMT and TPB, the SEM results demonstrated that “Perceived Vulnerability”, “Self-Efficacy”, “Response Efficacy”, “Response Cost”, “Subjective Norms” and “Institutional Trust” significantly affect the water-saving intention/behavior. Likewise, NAM based analysis as a moral approach, uncovered the significant effects of “Awareness of Consequences”, “Appraisal of Responsibility”, “Personal Norms” as well as “Place Attachment” and “Emotions” on water-saving intention.

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Flaring has been widely used in the upstream operation of the oil and gas industry, both onshore and offshore. It is considered a safe and reliable way to protect assets from overpressure and the environment from toxic gas using combustion. However, there are drawbacks to using flares, such as vibration and thermal radiation. Excessive contact with thermal radiation is harmful to offshore personnel and equipment. Research organizations and companies have invested time and money to combat this. Many technologies have been developed so far to reduce the risk of thermal radiation, one of them being the water curtain system. Several tests were done to see the effectiveness of the water curtain system in mitigating thermal radiation in an offshore environment. Each test varied in the flare output, wind speed, and the size of water droplets size of the water curtain. Later, the results of each test were compared and analyzed. The results showed that a water curtain system could be a solution to excessive thermal radiation that comes from an offshore flare. Moreover, the water curtain with smaller water droplets diameter gives a more favorable result in reducing thermal radiation. These results suggest that, although it offers simplicity and efficiency, designing an efficient water curtain system requires deep study. Various conditions, such as wind speed, flare intensity, and the size of the water droplets, plays a vital role in the effectiveness of the water curtain system in attenuating thermal radiation.