Papers by Keyword: Aeration

Abstract: One major feature of a granary is the uneven distribution of temperature and airflow. Due to the large variability in the parameters to be considered in characterizing the feature, a pilot test serves as the better way to performing the experiment, which subsequently affects the airflow velocity distribution, and is very difficult to determine by natural experiment. This paper develops a model for uneven airflow and temperature distribution through the layers of stored grains, relative to the indicated parameters. The study aims at predicting the various thermo-physical properties of maize grains using the developed model with the incorporated several expressions obtained, and compare with the measured values through the deployed pilot mini silo. To validate the model, the bin was aerated with forced air at constant humidity and temperature. A mini cylindrical silo was also developed and deployed with bulk grains for a pilot test. The predicted results were compared with the measured values of the temperatures obtained in the various locations of the pilot silo. The two results were closely related, thereby establishing the validity of our model. The model provides information on the direction of flow and velocity in each location within the stored volume of grains, and data for grain cooling, airing and drying in the bin. The developed model is useful for predicting the temperature distribution, airflow and the cooling time for bulk grains under varying aeration conditions, and suitable for optimizing the design and operation of granary systems.

Abstract: This study was aimed to determine the effect of electro-assisted and oxygen injection system to improve the effectiveness of the copper and iron removal in wastewater by phytoremediation system. The electro-assisted phytoremediation (EAPR) system was run with Vetiver grass (Vetiveira zizanioides L) as accumulator plant and 2 V of constant DC power supply using 2D cathode-pot electrode and air diffuser configuration on the aeration by air flow rate of 10 L/min. The effectiveness of phytoremediation, phyto-aeration,and phytoremediation on the wastewater treatment was compared and evaluated by measuring the decreasing of heavy metal concentration in the wastewater and accumulated inthe plant. Plant stress was monitored by the observation of phytomorphology changed and measurement chlorophyll content using UV-Vis Spectroscopy after the acetone extraction and heavy metal concentration was measured by Flame-Atomic Absorption Spectroscopy (Flame-AAS). The results showed that the decreasing of Cu and Fe concentration in the wastewater as much as 86.5% and 99,3%, higher than that phyto-aeration (82.35% and 99.20%) and phytoremediation (15.0% and 56.0%). The uptake profiles of heavy metal by plant indicated the enhancement ability of electro-assisted and aeration system to the phytoremediation has different results. For example in the root part, the heavy metal absorption occurred most often as following in phytoremediation>phyto-aeration>EAPR-aeration. Contrary results show in the EAPR-aeration system that the metal concentration quiet high translocation from root to shoot part by enhancement of electro-assisted and aeration system. High chlorophyll content and chlorophyll ratio in the plant under the EAPR-aeration system shows higher tolerance of the plant to the heavy metal concentration.

Abstract: The high organic material contained in wastewater released into the environment asresults of various sources of human activities, such as phosphorus, can cause eutrophication. Thestruvite crystallization in an aerated fluidized bed reactor is one of the methods which able toimprove the efficiency of phosphorus removal. In this study, a mixture of synthetic wastewaters andthe MgCl2 solution was treated in a fluidized bed reactor equipped with aeration to produce thestruvite which can be utilized as a slow release fertilizer. Subsequently, the effect of aeration atdifference influent flow rate was investigated to correlate with the changing of phosphorusconcentration in the reactor effluent. The experiments were conducted for 240 minutes with thevariation of aeration are 0.5 L/min to 1.5 L/min; variation of influent flow rate of syntheticwastewater is 150 ml/min to 350 ml/min, with a constant influent flow rate of MgCl2 solution is 50ml/min. These solutions were maintained at the condition of pH 9. The results showed that theoptimal efficiency of phosphor removal which accounted for 82.5% occurred when the aeration rateof 1.5 L/min in the influent flow rate of 150 ml/min. From these findings, it is revealed that theefficiency of P removal in wastewater is obtained by a crystallization process which utilizing anaerated fluidized bed reactor and by increasing the aeration rate and the reactants contact time.

Abstract: Aerobic biological treatment of waters in artificial conditions is carried out by symbiotic algobacterial community of attached and free-floating organisms in various types of aerotank and biofilters. With the blowers and mixers of different designs, the biomass is saturated with oxygen. Controlled air supply provides the necessary concentration of dissolved oxygen and stimulates the oxidation of organic and inorganic water pollutants symbiotic community.

Abstract: In the present study the effect of various additives (silica sand, silica fume, zeolite and cenospheres) as well as the aeration on the properties (consistency, density, compressive and bending strength) of lightweight concrete was studied. Density, compressive and bending strength of the lightweight concrete were substantially reduced by replacing silica sand with censopheres or by adding air entraining agent to the grout used for the preparation of the samples. Silica fume and zeolite admixture improved mechanical properties of the samples. Specific compressive strength of the cenospheres containing samples is comparable or even higher than the ones made of the mixes without the cenospheres.

Abstract: Protected escape routes enable the rescuing of persons to the outside of a building on fire. They are characterized, in particular, by strict requirements relating to the aeration of such spaces. However, the fulfilling of these limits may impact the monitored thermal characteristics of the respective internal areas. The outlined dilemma will be illustrated by way of an example of a protected escape route aerated by positive-pressure ventilation.

Abstract: Aeration step, one of the major stages in the Becher process was carried out on reduced Hatinh (Vietnam) ilmenite in NH₄Cl solution and the effect of several processing parameters were thoroughly investigated including the temperature, time, liquid/solid weight ratio (L/S), air flow rate and concentration of NH₄Cl solution. The obtained results showed that longer rinsing time, higher liquid/solid ratio and air flow rate facilitated metallic iron rusting. The rusted iron amount increased when the temperature increased and reached the highest value at 70°C. Variation of NH₄Cl concentration showed similar impact as that of temperature. The highest amount of rusted iron achieved at 0.5% NH₄Cl. Chemical analysis and XRD results indicated that 98% of metallic iron in reduced ilmenite has been transformed to iron oxides at an aeration condition (70°C, 8 h, L/S=7/1, air flow rate = 4 l/min and 0.5% NH₄Cl). Consequently, TiO₂ content from approximately 60% in the reduced ilmenite increased up to approximately 80% in the aerated rutile.

Abstract: As a developing country and one of the tropical tourism industry leaders, Malaysia is faced with environmental problems, such as the conversion of municipal solid waste landfill leachate into hazardous wastewater in mega cities. High concentrations of pollutants, toxic refractory component, and complex composition of landfill leachate have serious environmental impact. This study investigated a novel rapid treatment method to remove turbidity, suspended solid, color, and ammonia nitrogen. Bentonite augmented sequencing batch reactor with miscellaneous aeration (0.5–7.5 L/min) and contact time (1–3 h) is applied via response surface methodology in 13 runs. Results of this study show that in optimum circumstances, 93.63% of turbidity, 90.42% of total suspended solid, 76.33% of ammonia nitrogen (AN), and 45.96% color were removed in only three hours. Furthermore, natural bentonite is a cost effective adsorbent for landfill leachate treatment.

Abstract: Hydrogen sulfide is a common composition of natural gas. It is an important problem to develop suitable natural gas desulfurization technology for the present situation of China. Now, a novel process of H₂S abatement from gas streams has been investigated for chemical absorption of H₂S using a weak alkaline solution followed by the oxidation of the absorbed sulfide to elemental sulfur by naturally occurring microorganisms and alkaline solution regeneration for recycle and reuse in the process. This method is currently attracting more and more interests of researchers, because it requires little equipment, is inexpensive and produces only elemental sulfur, thus minimizing the production of pollutants. The biological oxidation process of the absorbed sulfides to elemental sulfur by Thiobacillus thioparus TYY-1 was studied in an airlift-loop reactor (effective volume=20L).Two efficiency factors including hydraulic remain time and the air aeration quantity were inspected. The air aeration quantity is key influence factor of desulfuration rate and elemental sulfur production rate. The investigation demonstrated that the optimum hydraulic remain time was 4—6h under the influent concentration of S^2- for 200 mg/L, and the best treatment effect of aeration was obtained at 120 —160L/h. With these conditions after 20 days of operation, the result showed superior performance of the bioreactor for desulfuration rate and elemental sulfur production rate, the conversion products were mainly sulfur and the production rate of SO₄^2- was low. The removal efficiency of sulfide was more than 99.5% while the maximum yield of sulfur was 88% approximately.

Abstract: In order to solve the problems of uneven mixing and aerating in municipal solid waste composting, we present a structural design of mechanical agitation biological reactor. The biological reactor system is composed of cylinder tank, agitator, motivation and drive device. The agitator shaft of reactor is hollow and has 24 holes under agitator blade. The article not only introduces the structural design and check of main body, and rack of reactor, but also the selection of type of arranger. The design of agitator gives consideration to both agitation and aeration, which makes air and materials mixed sufficiently during agitation and the fermentation is more fully.