Влияние гранулометрического состава песка на глубину проникновения дизельного топлива

Deployment of tanks for temporary storage of fuel on sand layer (a sand blanket) is an effective method to protect the soil from process-related spills. Asessment of the required thickness of the sand layer is important in practice, as it determines the layer’s protective properties when oil droplets fall on the surface. This paper investigates the dependences of the speed and depth of ingress of DT-Z-K5 diesel fuel on the grain size composition of the sand used as a protective layer. Substantiation has been given for the approach to the evaluation of the kinetics and to the depth of ingress of petroleum products into the sand, such approach being based upon the probabilistic movement of the fluid flow boundaries in the protective layer. It is proposed to describe the ingress of fuel into the sand layer in the coordinate system of the square root of the process time. Based on the results of the study, there have been established the dependences of the speed and depth of ingress of DT-Z-K5 fuel into the protective layer on the sand grain size and on the quantity of petroleum product leaked on the surface. It has been established that to create a protective layer preventing the ingress of fuel into the soil in the event of process-related leaks in temporary fuel storage tanks, it is optimal to use sand with 0.8 mm grain. Размещение резервуаров для временного хранения горючего на слое песка (песчаной подушке) является эффективным способом защиты грунта от технологических проливов. Практическое значение имеет оценка необходимой толщины песчаного слоя, которая определяет его защитные свойства при попадании на поверхность капель нефтепродукта. В настоящей работе исследованы зависимости скорости и глубины проникновения дизельного топлива ДТ-З-К5 от гранулометрического состава частиц песка, используемого в качестве защитного слоя. Обоснован подход к оценке кинетики и глубины проникновения нефтепродукта в песок, основу которого составляет вероятностное движение границ потока жидкости в защитном слое. Предложено описывать проникновение топлива в слой песка в системе координат корня квадратного из времени процесса. По результатам исследования установлены зависимости скорости и глубины проникновения ДТ-З-К5 в защитный слой от размера частиц песка и количества вносимого на поверхность нефтепродукта. Определено, что для создания защитного слоя, исключающего проникновение топлива в почву при возникновении технологических протечек резервуаров временного хранения горючего, оптимально использовать песок с размером частиц от 0,8 мм. Предложенный подход по получению зависимостей глубины проникновения топлива от условного времени можно использовать для оценки распределения топлива в слоях песка с различными размерами частиц.

Parameters for effective sand filtration of Schistosoma mansoni cercariae from water

Schistosomiasis is a water-based neglected tropical disease that is prevalent in over 78 countries. It affects communities that are reliant on freshwater bodies contaminated with schistosome cercariae for their daily water activities. Whilst treatment with the drug praziquantel is relatively effective, it does not prevent reinfection. One option for reducing schistosomiasis infection is providing at-risk communities with treated water, thereby reducing contact with cercaria-infested water for activities such as bathing or doing laundry. This study aims to establish design guidance for sand filtration to remove schistosome cercariae from water. Four sand filters were tested, varying from 300 to 2,000 μm in sand grain size. Each filter was tested with a sand depth of 20 cm, which was increased until no cercariae were detected in the effluent. The required filter depth to remove 100% of cercariae ranged between 40 and 70 cm depending on sand grain size. Cercaria removal was more effective in filters with smaller sand grain size and larger filter depth. These results are valid for intermittent flow, for up to six cycle flushes. While more rigorous testing is needed, these initial results suggest that sand filters can be an effective way to treat cercaria-contaminated water in low-income settings.

Effect of Sand Grain Size on Spontaneous Imbibition of Surfactant Solution

<em><span>In spontaneous imbibition researches, surfactant has been employed to control interfacial tension (IFT) and wettability. In this paper, the evaluation of grain size effect on spontaneous imbibition of surfactant solution is presented. In this work, the synthetic porous media (sand packs) with uniform and non-uniform grain size from 30 mesh to 100 mesh were made. The porous media were initially saturated by oil. Then they were immersed in brine with salinity of 62 to 40,000 ppm for 24 hours. After that, the porous media were immersed in surfactant solution with concentration of 0.2% for another 24 hours. The total oil recovery during these treatments was measured. The experiment was separated into three parts in order to investigate the effect of uniform grains, non-uniform grains, and salinity in spontaneous imbibition. The results show that grain size and porosity were proportional to oil recovery. In the case of porous media with uniform grain size, the effect of grain size on recovery factor is stronger than that of porosity. Meanwhile the salinity has an the optimum condition for </span><span lang="EN-US">a maximum </span><span>recovery factor. In this study, it happened at salinity of 20,000 ppm.</span><span> <span lang="EN-US">Oil recovery factors observed in this study ranged from 66.7% to 91.1%.</span></span></em>

Abrasive Wear Behavior of Cryogenically Treated Boron Steel (30MnCrB4) Used for Rotavator Blades

Rotavator blades are prone to significant wear because of the abrasive nature of sand particles. The aim of this research work is to investigate the effect of cryogenic treatment and post tempering on abrasive wear behavior, in the presence of angular quartz sand (grain size of 212–425 μm), of rotavator blade material of boron steel (30MnCrB4). Cryogenic treatment has caused an improvement in the abrasive wear resistance and microhardness of 30MnCrB4 by 60% and 260.73%, respectively, compared to untreated material due to enhancement in hardness, the conversion of retained austenite into martensite, and the precipitation of secondary carbides in boron steel after exposure to cryogenic temperature. Economic analysis justifies the additional cost of cryogenic treatment.