Results 1 - 10 of 1583
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[en] The use of mineral membranes on metallic supports has provided a novel solution to the problem of filtration by the reverse osmosis process. A new reverse osmosis membrane is described which is capable of resisting high operational temperatures (1200C), fluctuations in pH(3 to 12) and high pressure (100 bar), as well as significant chlorine concentrations. In addition, the membrane can be regenerated in-situ on the same porous metal support. Numerous membranes can thus be used over the multi-year life of the porous support. Moreover, accidental damage to the membrane is of no great consequence as the membrane itself can be easily replaced. The life of the installation can thus be extended and the overall cost of filtration reduced. The membrane's various applications include water and effluent treatment in the nuclear power industry. (author)
[en] The aim of presented studies is to investigate of influence of ultrasonic assistance on both osmotic dehydration and convective drying. A wide range of different materials, as well as several osmotic agents were tested. The obtained results show that the use of ultrasound always accelerates the investigated processes. The application of ultrasound may reduce the energy consumption of drying. Qualitative studies of dried materials do not give a definite answer about the effect of ultrasound on the quality of the products. Mathematical modelling of the ultrasound assisted drying indicates that so named “vibration effect” plays the biggest role in convective drying acceleration. (Author)
[en] In this present work the diagnosis results of a reverse osmosis desalination unit are reported. Since 1997, the desalination unit was supplying a 1200 bed hotel. The feed water was driven from a well situated 300 m away form the sea. The water has an approximate salinity of 6gg.L-1. The unit was producing 600 m3 per day of desalinated water with a Total Dissolved Salts (TDS) of nearly 400 mg.L-1. The desalination unit has two stages with 67 pour cent and 42 pour cent yields respectively giving an average yield of 81 pour cent. The behavior of all water streams with respect to aggressiveness and scaling tendency was assessed. The 2nd stage reject water was shown to exhibit a very high scaling behavior with an instantaneous precipitation in the absence of feed water chemical treatment. The analyses have shown that the produced water was very aggressive. The second stage module autopsy has revealed a sharp decrease of the membrane performances because of mineral as well as organic fooling buildup. The inorganic scale was essentially made of coesite and calcite and kaolinite clay. The presence of silica and clay could be attributed to an inadequate filtration pre-treatment process that was not able to retain all the suspended matter in the feed water. Whereas the presence calcite crystals at the membrane surface, reveals that the chemical inhibition performed at the pre-treatment process without adjusting the water pH was not able to prevent calcium carbonate precipitation. A periodic acid wash of the 2nd stage membranes is then necessary to guarantee this stage desired objectives.
[en] The study was conducted to evaluate the effect of NaCl salinity on germination and emergence of Physalis ixocarpa and Physalis peruviana. Seeds of P. ixocarpa and P. peruviana were germinated by the use of 0, 30, 60, 90, 120 and 180 mM NaCl solutions in petri dishes. Final germination percentage (FGP) decreased with the increase in NaCl concentration. Both species germinated at the ranges of salinity. P. peruviana gave the greater germination percentages under salt stress than P. ixocarpa. NaCl salinity at different concentrations adversely affected germination rates. For seedling growth, seeds of both species were sown at 10 mm depth in plastic trays filled with peat to determine final emergence percentage (FEP). The trays were irrigated manually to saturation every day with 0, 30, 60, 90, 120, 150 or 180 mM NaCl solutions to maintain the level of salinity. Salinity affected seed emergence and seedlings growth more than seed germination. The study showed that no emergence of Physalis was observed at 90, 120 and 180 mM NaCl salinity. Fresh and dry weights of normal seedlings were also evaluated. Salt stress significantly decreased the plant fresh and dry weight of both species. Based on the results of the experiment, it can be concluded that seedling emergence and growth is more sensitive to salt stress than seed germination in Physalis. (author)
[en] Pervaportion is the selective evaporation and separation of one component of liquid stream by membrane, which is in direct contact with liquid mixture. This makes pervaporation more energy efficient process. For this study pervaporation apparatus was designed and developed in line with criteria presented in the literature on the subject. Polymeric membrane obtained from Shangai Megavision, China was used in the membrane cell. The membrane unit can also be used for reverse osmosis, gas separation, ultra and nano filteration by simply replacing membrane with other membrane compatible for the selected process. Experiments were performed to separate water from amixture of water/ ethanol. Change in concentration of retentate (feed stream going back to feed tank from membrane cell) with time at different temperatures 60 deg. C, 70 deg. C and 80 deg. C was observed. Moreover, effect of temperature on flux was also studied. (author)
[en] Osmotic dehydration of apple was modeled considering the mechanisms involved in the solutes transfer within the plant matrix: impregnation and diffusion. The model mathematical writing includes the impregnation layer thickness, the diffusion thickness, a water bulk flow and the convective resistance. Apple cylinders were dehydrated at 30, 50 ° C and 30, 50 ° Brix and a motion of 0.15 m/s. The Reynolds number was of 250 for 30°C-30°Bx and 500 for 50°C-50°Bx. Schmidt numbers was of 4000 for 30 ° C-30 ° Bx and 4200 for 50 ° C-50 ° Bx. (Author)
[en] The aim of this work was to evaluate the influence of vacuum application on the phenolic acid content of osmodehydrated eggplant, carrot and beetroot samples. The contents of catechins and chlorogenic acid were determined by HPLC analysis. Changes in the contents of phenolic acids after the osmotic processes were observed. It was found a reduction in catechins and chlorogenic acids, probable due to the migrationand degradation losses. In a general way, the vacuum reduced the catechin and chlorogenic acid contents, compared to the osmotic dehydration at atmospheric pressure. (Author)
[en] The desalination of seawater via reverse osmosis (RO) has shown promise as a technology for overcoming stress on water resources (Elimelech and Phillip, 2011; Darre and Toor, 2018). However, membrane fouling may be the main obstacle for wider implementation of membrane filtration since usually causes higher costs of energy, operation and maintenance (Gao et al., 2011). Of all types of fouling, biofouling is the most uncontrollable because it is caused by ungovernable growth of microorganisms and EPS production, leading to higher operating pressures, more frequent chemical cleanings and shorter membrane lifetimes (Boyce, 2011). Therefore, it can be concluded that membrane biofouling is a common problem resulting in a shortened lifespan of desalination system (Al-Ahmad, 2011).
[en] This paper presents an update of a dynamic library of reverse osmosis plants (ROSIM). This library has been developed in order to be used for optimization, simulation, controller testing or fault detection strategies and a simple fault tolerant control is tested. ROSIM is based in a set of components representing the different units of a typical reverse osmosis plant (as sand filters, cartridge filters, exchanger energy recoveries, pumps, membranes, storage tanks, control systems, valves, etc.). Different types of fouling (calcium carbonate, iron hydroxide, biofouling) have been added and the mathematical model of the reverse osmosis membranes, proposed in the original library, has been improved.
[en] Pirarucu (Arapaima gigas Schinz) farming has been encouraged and, among meat preservation techniques, the salting process is a relatively simple and low-cost method. The objective of this work was to study the sodium chloride diffusion kinetics in Pirarucu during wet salting. Limited volumes of brine (20% w/w) were employed with wet salting assays carried at 3, 4 and 5 brine/muscleratios, and brine temperatures of 10, 15 and 20oC. The analytical solution of Fick's second law considering one-dimensional diffusion through an infinite slab in contact with a well-stirred solution of limited volume was used to calculate the effective salt diffusion coefficients. Salt diffusivities in muscle were found to be in the range of 2.07 and 8.80 ×10-10 m2/s. The wet salting of Pirarucu is greatly influenced by temperature and by the brine/muscle ratio by volume. (Author)