Results 1 - 10 of 511
Results 1 - 10 of 511. Search took: 0.02 seconds
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[en] The one-piece garement in flexible airtight material includes an air feeding device (valve or pressure reducing valve) and a nonreturn valve air outlet, a branched network of pipes integral with the clothing from the inlet up to the different parts where air is needed
[fr]Combinaison protectrice comportant une peau realisee en un materiau etanche souple, caracterisee en ce qu'elle comporte, d'une part au moins un dispositif d'alimentation en gaz (robinet et/ou detendeur) et au moins un dispositif de sortie de gaz a clapet anti-retour et, d'autre part, un reseau ramifie de conduites solidaire de la peau de la combinaison et s'etandant depuis le dispositif d'alimentation jusque dans les differentes parties de la combinaison ou l'amenee de gaz est desiree
[en] Microorganisms play an important role in leaching and accumulation of uranium and other heavy metals. Some parameters which affect the efficiency of microoganisms in recovering uranium were previously studied. In this study, the effect of aeration, culture filtrate and size of inoculum of five Iraqi iron oxidizing bacteria, on leaching of uranium from claystone were studied. As a results of experimentation conducted, no significant increase in uranium leached was detected as a function of increasing in the size of inoculum for all isolates
[en] This study investigates the alkaline oxidation pretreatment process of Zarshuran refractory gold ore. Taguchi method-orthogonal array design (OAD) is applied to evaluate and optimize the influence of five main factors including solution pH, aeration rate, agitation speed, temperature, and oxidation time. In order to establish relationship between the gold dissolution rate and influential factors, a linear regression model with R2 of 0.9706 is fitted to experimental data. The results indicated that in the range studied, the agitation speed does not have any significant impact on the gold recovery, while oxidation time and temperature were the most significant factors. Au recovery increased with increasing the aeration rate, pretreatment time, and temperature as well as decreasing the solution pH. Using Taguchi orthogonal array optimization technique (OAOT), the maximum gold recovery was about 96.72%. Also, the optimal conditions were 11 for solution pH, 150 ml min−1 for aeration rate, 240 rpm for agitation rate, 50 °C for temperature, and 24 h for oxidation time. (paper)
[en] In this paper the effect of aeration on gamma irradiation of sewage sludge was investigated to examine the potential solubilization of solids in sewage sludge to ultimately reduce the solids volume for disposal. Results showed that aeration increased the effectiveness of gamma radiation. The efficiency of sludge solubilization with aeration was increased by around 25% compared to that without aeration at an irradiation dose of 2.5-9 kGy. The soluble protein, polysaccharide and humic (like) substance concentrations were higher under aerated conditions. With aeration the overall reaction appears to be oxidative as evidenced by the higher nitrate and nitrite ion concentrations in solution.
[en] A parallel, bench-scale study was undertaken to study the effect of grinding/blending biological solids followed by subsequent aeration for 24-hours on overall sludge production. This was compared to a completely-mixed system from which solids were wasted directly back to the aeration basin. In essence, both treatment trains employed total recycle of the waste biological solids, except that the solids from Train 2 were ground and aerated prior to re-introduction. The bench-scale reactors were continuously operated from November through December 2000 and from January through April 2001. Temperature of the wastewater during the first and second runs was maintained at 14o C and 25o C, respectively. Each parallel train was fed synthetic wastewater at a flow rate of approximately 2.25 gallons per day resulting in a hydraulic detention time of approximately 13 hours. Samples of the influent, effluent, and mixed liquor were collected weekly and the following analyses were performed: COD, pH, temperature, total solids, suspended solids, volatile suspended solids, dissolved solids, and oxygen uptake rate (OUR). Results of the study indicate that the system in which the solids were ground and re-aerated produced less sludge than the conventional system. Substrate removal rates were the same for both systems. Statistical analyses using the analysis of variance indicated the results were significant at the 95 % confidence level. (author)
[en] Research highlights: → There is an optimum aeration rate in the MBMBR process compartments. → Optimum aeration rate maximizes nutrients removal. → Optimum aeration rate minimizes membrane fouling. → Both aeration rates in MBBR and membrane compartment can affect on membrane permeability. - Abstract: In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 and 85 L h-1 and a specific aeration demand per membrane area (SADm) of 1.2 and 0.4mair3 m-2 h-1, respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SADm significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SADm were 151 L h-1 and 0.8-1.2mair3mmembrane-2 h-1, respectively.
[en] Radon removal can, with a good effect, be used to remove radon from well water. For installations based on aeration only the radon gas is removed, not the radon progeny. The aim of the study is to get an indication of the effect on short-lived progeny and possibly of implications for the effective dose. The short-lived radon progeny have been investigated in the raw and the cleaned water from six private wells where radon aerator systems based on aeration and recirculating of the water have been installed. The results from this pilot study indicate that the short-lived radon progeny in some cases follow the water to the tap for consumption to such an extent that the problem with the remaining short-lived progeny should be considered. The extent of the study is not sufficient for general conclusions. However, it is important to stress that the effective dose from the short-lived progeny is always lower than it would have been from the radon, when no radon removal is used. (author)
[en] Physical mechanism of compression pulse generation by steam bubble collapse, when actual cavitation cannot take place, is considered. Evaluation formula describing this event is obtained. Combined experiments, the results of which are in fair agreement with the theory proposed are presented
[en] The ore is ground and mixed with sulphuric acid to give a moist ore containing a sulphuric acid concentration of less than 4N without forming a continuous liquid phase. The moist ore is cured at from 500 to 1000 while passing an oxidising gas through it. Using this method it is possible to achieve uranium extractions of % or better in 24 hours or less. This invention provides an improved method for acid leaching of uranium from its ores and especially from those ores which contain uranium as a finely-diaseminated refractory material, such as brannerite or uraninite. (LL)