Study of the oil geopermeation patterns: A case study of ANSYS CFX software application for computer modeling.

Mathematical simulation of oil permeation through the porous media is the crucial topical problem in the framework of localization and liquidation of emergency oil spills. The main objective of this study was to establish the oil contamination level and oil contamination depth for different soil types which is of particular relevance from the standpoint of environmental safety. Four types of soils were taken for investigation as follows Cambisol with sand texture (No. 1), Luvisol (gray forest), with loamy sand texture (No. 2), Black Typical Chernozem with sandy loam texture (No. 3), Kastanozem (pine forest terrace under the pines) with sand texture (No. 4). The task of predicting the temporal-spatial indicators of oil permeation in the soil during accidental spills was solved using ANSYS CFX software allowing to simulate the absorption amount of oil into the ground. Visualization of oil concentration and velocity for studied soil samples was carried out. Determination of petroleum hydrocarbons concentration by the gravimetric method indicated a direct correlation between oil content in the soil and the porosity of the investigated soil samples. In order to determine the rate of hydrocarbon permeation through the dry and wet soil layer comparative experiments were carried out for the following systems: oil - dry soil and oil - wet soil. Permeation coefficients for dry samples from No. 1 to No. 4 were set at the rate 0.0073 m ∙ day-1, 0.0077 m ∙ day-1, 0.0083 m ∙ day-1, 0.0067 m ∙ day-1 respectively, and for wet soils 0.0083 m ∙ day-1, 0.0093 m ∙ day-1, 0.0093 m ∙ day-1, 0.0083 m ∙ day-1 consequently. The obtained hydrocarbon permeation coefficients for different systems allow calculating the depth of oil penetration for a given time after the spill, taking into account soil moisture. The dependence of oil concentration and permeation rate distribution through the soil fully reflects reliability of the experimental data, thereby confirming the verification of the adequacy of the computer model based on the ANSYS CFX software.

The Influence of Phosphogypsum Addition on Phosphorus Release in Biochemical Treatment of Sewage Sludge.

The paper is focused on the research of biochemical treatment of sewage sludge and phosphogypsum under sulphate-reducing conditions with a phosphorus release process. The theoretical foundations of the work were based on the biochemical formalization using the principles of autocatalysis of natural systems. During the experimental research for the control of physicochemical parameters of the process spectroquantic, X-ray fluorescence analysis and other techniques were used. A schematic model of the dephosphatation process under anaerobic stabilization of sewage sludge and phosphogypsum was developed. The increase of phosphogypsum dosage had a close correlation with the release of phosphate ions. At the stimulating action of the phosphogypsum additive, a 2.5⁻5.0-fold increase in soluble phosphate concentration was observed. The rational dose of phosphogypsum was determined. Along with an increase the ratio of COD (Chemical Oxygen Demand)/phosphogypsum to 0.1, an increase in the phosphate ions in solution was observed. A further increase in the ratio of COD/phosphogypsum did not affect the concentration of phosphate ions in solution.