Magdalena Ryżak

Influence of the Sand Particle Shape on Particle Size Distribution Measured by Laser Diffraction Method

Abstract The aim of this paper was to show how the shape of sand particles affects the results of particle size distribution obtained by the laser diffraction method. On the basis of the results obtained one can conclude: the shape of the investigated particles influences particle size distribution obtained by the laser diffraction method. This phenomenon occurs in the sand fraction, as shown in our investigation. The importance of this effect depends on the type of the measured material and on the aim of the investigations. For most researchers in soil science and sedimentology who investigate sand fractions, this impact can be negligible. Further investigations with other soil and sediment fractions are needed.

MEASUREMENT OF ACTIVATED SLUDGE PARTICLE DIAMETERS USING LASER DIFFRACTION METHOD

Abstract The paper presents a study on the possibility of using the laser diffraction method for measuring the size of the activated sludge particles. Susceptibility of the particles to mechanical disintegration, dependent on the programmed value of stirring intensity, was observed (stirring was caused by required dynamic flow of analysed suspension through the measurement unit). According to the conclusions presented in this paper, it may be assumed that the laser diffraction method can be applied for measurement of activated sludge particle diameters under the following conditions: 1) the size of activated sludge particles measured by the laser diffraction method is not a real value, but after standardisation of measurement conditions can be treated as a parameter describing the sludge; 2) the particle diameters of activated sludge should be stabilised before the measurement, eg by mixing in the measurement unit or by ultrasound waves application. Abstrakt Praca dotyczy oceny możliwości wykorzystania dyfrakcji laserowej do badania rozmiarów kłaczków osadu czynnego. W czasie pomiarów zaobserwowano podatność analizowanych cząstek na zniszczenie mechaniczne zależną od zaprogramowanej intensywności mieszania (mieszanie i przepompowywanie jest wymagane w celu wymuszenia przepływu analizowanych zawiesin przez układ pomiarowy). Na podstawie wniosków opracowanych na podstawie prowadzonych badań można stwierdzić, iż metoda dyfrakcji laserowej może być stosowana do pomiarów rozmiarów kłaczków osadu czynnego pod następującymi warunkami: rozmiary kłaczków oraz pozostałych elementów osadu czynnego uzyskane w czasie pomiarów nie mogą być traktowane jako wartość bezpośrednia opisująca rozmiary kłaczka, lecz po standaryzacji warunków pomiarowych może być traktowana jako ilościowy parametr opisujący właściwości osadu czynnego. Przed pomiarem metodą dyfrakcji laserowej osad czynny powinien być uprzednio stabilizowany na przykład za pomocą mieszania w układzie pomiarowym bądź też za pomocą ultradźwięków.

Effect of Soil Moisture Content on the Splash Phenomenon Reproducibility

One of the methods for testing splash (the first phase of water erosion) may be an analysis of photos taken using so-called high-speed cameras. The aim of this study was to determine the reproducibility of measurements using a single drop splash of simulated precipitation. The height from which the drops fell resulted in a splash of 1.5 m. Tests were carried out using two types of soil: Eutric Cambisol (loamy silt) and Orthic Luvisol (sandy loam); three initial pressure heads were applied equal to 16 kPa, 3.1 kPa, and 0.1 kPa. Images for one, five, and 10 drops were recorded at a rate of 2000 frames per second. It was found that (i) the dispersion of soil caused by the striking of the 1st drop was significantly different from the splash impact caused by subsequent drops; (ii) with every drop, the splash phenomenon proceeded more reproducibly, that is, the number of particles of soil and/or water that splashed were increasingly close to each other; (iii) the number of particles that were detached during the splash were strongly correlated with its surface area; and (iv) the higher the water film was on the surface the smaller the width of the crown was.

Using the Image Analysis Method for Describing Soil Detachment by a Single Water Drop Impact

The aim of the present work was to develop a method based on image analysis for describing soil detachment caused by the impact of a single water drop. The method consisted of recording tracks made by splashed particles on blotting paper under an optical microscope. The analysis facilitated division of the recorded particle tracks on the paper into drops, “comets” and single particles. Additionally, the following relationships were determined: (i) the distances of splash; (ii) the surface areas of splash tracks into relation to distance; (iii) the surface areas of the solid phase transported over a given distance; and (iv) the ratio of the solid phase to the splash track area in relation to distance. Furthermore, the proposed method allowed estimation of the weight of soil transported by a single water drop splash in relation to the distance of the water drop impact. It was concluded that the method of image analysis of splashed particles facilitated analysing the results at very low water drop energy and generated by single water drops.

A System for Recording the Dynamics of the Water Drop’s Impact on a Surface

The splash phenomenon is the first stage of water erosion on the soil. It occurs when the water drops of the rain strike the surface. The impact of the water drop is fast. But if one has a fast enough measuring system, it can be considered as a temporally extended phenomenon. The aim of this paper is to describe a system for the measurement of the dynamic of the changing forces when a water drop interacts with the surface during impact. The constructive assumptions and validation of the measurement system, which has been based on piezoelectric sensors, are also presented. The system allows one to measure the changes of the force with the frequency of 150 kHz. The maximum force is 200 N, which is quite sufficient for all sizes of water drops which occur in nature and their maximum speeds. The results of test measurements, that is, the changes of the force obtained from water drops falling on the sensors, are also shown.

The differences in crown formation during the splash on the thin water layers formed on the saturated soil surface and model surface

Splash is the first stage of a negative phenomenon–soil erosion. The aim of this work was to describe the crown formation quantitatively (as part of the splash erosion) and compare the course of this phenomenon on the thin water film formed on a smooth glass surface and on the surface of saturated soil. The height of the falling water drop was 1.5 m. The observation of the crowns was carried out by high-speed cameras. The static and dynamic parameters of crown formation were analysed. It was found that the crowns formed on the water film covering the saturated soil surface were smaller and the time intervals of their existence were shorter. In addition, the shapes of the crowns were different from those created on the water layer covering the glass surface. These differences can be explained by the slightly different values of surface tension and viscosity of the soil solution, the greater roughness of the soil surface and the lower thickness of the water film on the soil surface.

Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing–most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon’s characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

The shape and dynamics of the generation of the splash forms in single-phase systems after drop hitting

The splash phenomenon is being increasingly explored with the use of modern measurement tools, including the high-speed cameras. Recording images at a rate of several thousand frames per second facilitates parameterization and description of the dynamics of splash phases. This paper describes the impact of a single drop of a liquid falling on the surface of the same liquid. Three single-phase liquid systems, i.e., water, petrol, and diesel fuel, were examined. The falling drops were characterized by different kinetic energy values depending on the height of the fall, which ranged from 0.1 to 7.0 m. Four forms, i.e., waves, crowns, semi-closed domes, and domes, were distinguished depending on the drop energy. The analysis of the recorded images facilitated determination of the static and dynamic parameters of each form, e.g., the maximum height of each splash form, the width of the splash form at its maximum height, and the rate of growth of the splash form. We, Re, Fr, and K numbers were determined for al...

Changes in Textural and Geo-Chemical Features of Alluvia in the Western Part of the Lublin Upland Over the Past 1000 Years

Changes in Textural and Geo-Chemical Features of Alluvia in the Western Part of the Lublin Upland Over the Past 1000 Years In the study the authors analysed the diversity of the textural indices and selected geo-chemical features of sediments that accumulated in the bottoms of valleys in the western part of the Lublin Upland over the past 1000 years. Detailed studies were performed for six profiles with known stratigraphy. The sediments studied varied little in terms of textural features, with a general trend for particle diameters to increase as the depth increased. The characteristics of the sediments indicate a significant role of material supply from the slope systems (mainly gullies) to the bottoms of river valleys. The heavy metal content was characterised by greater vertical variation. In most of the profiles, the youngest deposits were characterised by greater levels of Cd, Cu, Pb and Zn, with enrichment indexes at an average of 1.5-2.5. The observed diversity of the features of sediments, particularly the geo-chemical features, should be attributed to the effect of human activity in the area studied.