Search

The paper proposes an engineering calculation method, on the basis of which it was proposed to use three ultrafiltration units connected in series for the ultrafiltration separation of cheese whey components. These installations operated in a continuous cycle, which contained membrane devices with the calculated parameters. This paper describes a scheme for obtaining whey protein concentrate from cheese whey formed during the processing of milk into rennet cheese. The scheme works on a tubular ultrafiltration apparatus - it was accepted for development at ChS VERO LLC. In our proposed scheme, an electrodialysis unit is used, since this unit has more advantages than others. The advantage of the electrodialysis unit is the demineralization of technological solutions with a high dry matter content (concentrated whey, gelatin, sugar syrup, chicory syrup, glycerin) and tolerance. The productivity of the selected electrodialysis plant allows the concentrated volume to be brought to a demineralization level of 80% in about 1 hour. The work describes in detail the scheme of the concentration line for LLC "VEKSHA" and LLC "ChS" VERO "with obtaining dry whey concentrate, including a tube-type ultrafiltration apparatus. Also substantiated is the value determined by the ratio of the results of production and labor costs and funds for the production of cheese whey for LLC "ChS" VERO "and LLC" VEKSHA ". The expected economic effect from the introduction of the line will be 4200 thousand rubles. for LLC "VEKSHA" and 980 thousand rubles. for LLC "ChS" VERO "per year in prices of 2021.

For the qualitative application of ultrafiltration processes for the concentration and purification of food solutions, both experimental studies and a mathematical description of the processes of the membrane separation process of solutions from the standpoint of the development of computational mathematical models are required. In this work, by analytical solution of equations, that is, by the method of finite differences, mathematical equations are solved. To obtain the system, the flow continuity equations, convective diffusion equations, Navier-Stokes equations and flow equations with boundary conditions were solved in order to build a mathematical model of the process of ultrafiltration protein concentration in cheese whey in the production of rennet cheeses. As a result of the analytical solution of the equations, a system of mathematical equations was obtained that allows one to construct a profile of changes in the flow rates of the solution along the cross-section of the intermembrane channel and to determine the protein concentration in cheese whey along the length of the tubular ultrafiltration element BTU 05/2 of industrial type. The obtained mathematical model makes it possible to theoretically describe the process of ultrafiltration protein concentration in cheese whey along the entire length of the membrane channel of the tubular element under laminar and transient regimes of solution flow. The resulting system of mathematical equations makes it possible to find the numerical values of the mass flow rate of cheese whey, make it possible to calculate the specific output flow when the transmembrane pressure changes and to calculate the concentration of solutes in the secondary milk raw materials on the left and right ultrafiltration membrane of the intermembrane channel. The adequacy of the developed mathematical model was carried out by comparing the calculated and experimental data on the specific output flow when the transmembrane pressure in the intermembrane channel changes from 0.1 to 0.25 MPa with ultrafiltration concentration of cheese whey. The deviation of the calculated data found by the mathematical model from experimental studies obtained on a semi-industrial tubular ultrafiltration plant BTU 05/2 using semipermeable membranes, in which the active layer is made of fluoroplastic, hemisulphone and polyethersulfone, did not exceed 10%.

The paper presents the results of experimental data on the kinetic characteristics of ultrafiltration tubular elements, such as the output specific flow, retention coefficient, diffusion permeability coefficient, distribution coefficient. To study the purification of milk whey, we used tubular ultrafilters BTU 05/2 with membrane material fluoroplast (F), polyethersulfone (PESF), polysulfone (PS). For theoretical calculation of the retention coefficient, output specific flux, diffusion permeability coefficient, distribution coefficient, mathematical expressions were developed and empirical coefficients were obtained. The developed mathematical expression describes the experimental data with good reliability. The obtained experimental and calculated data can be used with high reliability in calculating mass-transfer fluxes of substances through a semi-permeable membrane, as well as in engineering methods for calculating and predicting efficiency, and using membrane processes for concentrating serum. The protein concentration in real milk whey was determined by formol titration. On the basis of the studies carried out, the dependence of the growth of the output specific flow on pressure was established, that the optimal pressure for concentrating milk whey on the ultrafiltration membranes we have chosen is 0.25 MPa. For three types of ultrafilters, the experimental value of the coefficient was within 99% for protein. For the theoretical calculation of the retention coefficient, a program in the MAXIMA language was developed and registered. Due to the method of applying the membrane to the reinforcing element, the membrane material polyethersulfone (PESF) and polysulfone (PS) have a substrate, due to which they sorb more substances on themselves, because of this, the diffusion permeability coefficient and the distribution coefficient are much higher than that of a filter element with membrane made of fluoroplastic (F), which does not have a substrate.

Experimental data on the retention coefficient and the output specific flow are obtained. The test solutions were goat and cow's milk whey after obtaining cheese. The description, general view and technological scheme of a pilot installation of a tubular type are given. The studies were carried out on semipermeable tubular type ultrafiltration membranes manufactured by AO "ZAVKOM". Based on the studies, graphical dependences of the retention coefficient on the specific output stream were constructed and analyzed. During the analysis, it was noted that with an increase in the output specific flow of the solvent, the retention coefficient decreases. The reason for this is the boundary layers of fat and protein formed in the near-membrane layers, which prevents the passage of protein molecules through the pores of the membrane. Also during the experiment, it was noted that goat milk serum has a more oily structure and requires prior separation. For the theoretical calculation of the retention coefficient and specific output stream, mathematical expressions are developed and numerical values of the values of empirical coefficients are obtained. The developed mathematical expressions describe the experimental data with good confidence. The obtained experimental and calculated data can be used with great reliability in the calculations of mass-transported flows of substances through semipermeable membranes, as well as in engineering methods for calculating and predicting the effectiveness of the use of membrane processes for the concentration of whey.

The paper examines the specific output stream and the rate of detention of a semi-permeable ultrafiltration membranes, UPM, UAM150, UAM200 in the separation process, waste starch and syrup production JSC., the company "Krakhmaloprodukt" low-pressure baromembrane method. As a result of the analysis of experimental data, the dependence of the retention factor of ultrafiltration membranes UPM-K, UAM150, UAM20 at different concentrations of the dissolved substance was obtained and analyzed. For the theoretical calculation of the process of ultrafiltration separation technology solutions of starch and syrup production modified mathematical expression for the factor of detention and the specific output stream and the numerical values of the empirical coefficients. Ultrafiltration for the separation of waste starch and syrup production the technological scheme of purification, separating the main elements of which was the pre-filter, biofilter, cascade ultrafiltration apparatus, centrifugal and plunger pumps, as well as the adsorption column.The application expediency of the selected apparatus with flat chambers lies in the simplicity of their production technology and in the self-selection possibility of optimum type membranes. It is possible in the presented apparatuses to usemembranes of different types and in the course of the evaluation experiment to establish to what extent they correspond to the most important technological parameters of the process, such as specific output flow, retention factor and resistance to pollution. It is noted that the specific output flow of ultrafiltration membranes decreases with the increase of the initial concentration of the dissolved substance, as the viscosity of the solution increases and its osmotic pressure increases, and the decrease in the retention factor of ultrafiltration membranes is caused by the formation of diffusion boundary layers on the active layer of membranes.

This work is devoted to the study of specific solvent stream in baro membrane separation processes in the biochemical industry. The main indicators, which characterize baromembranes technology, are productivity and quality division. Performance of baromembrane separation is estimated by the specific output or specific solvent stream, which is equal to the permeate flow per unit working area of the membrane per unit of time, and also determines the speed of the process of baromembrane division. This parameter depends on the material of the membrane, the nature of the solutes and their concentrations in the solution, the operating pressure, temperature and hydrodynamic processes. The article analyzed the specific solvent flow, which mathematically described by the equation based on Darcy's Law. This law establishes proportional dependence on the driving force of the process, the concentration and type of membrane. For the research was used following technique. The initial stage was to preliminary cleaning of membranes from impurities, checking the integrity of individual units, launching in work mode for a time period of 18 hours. Then there was a preliminary experience for the establishment of a permanent performance with a factor of retention membranes. After that was done a series of basic experiments, the results of which were used for calculate of specific solvent stream. As a result of investigations made certain conclusions. Specific solvent stream decreases with increasing concentration. In ultrafiltration membranes the specific solvent stream is higher than in reverse osmosis membranes. This phenomenon depends on the type of membrane. When the pressure increases the flow of the solvent and performance of baromembrane separation of solutions increases too. Specific solvent stream are influenced by concentrating polarization, gelation and sedimentation, which are formed as a result of increasing pressure and adsorption on the membrane surface.

Retained on a membrane solute in reverse osmosis separation of biological fluids at the surface of the membrane gradually accumulates and forms a boundary layer, where its concentration is higher than in the bulk. Increased concentration of solute in the solution at the membrane surface causes a diffusive flow of solids from the membrane surface into the bulk solution. After some time in the system t is a stationary state. A convective flow of solute to the membrane surface will be balanced by the sum of the fluxes of solute through the membrane and from the membrane surface into the bulk solution, i.e. in the case of concentration polarization is formed an edge of the diffusion layer. It is established that the concentration-polarization in reverse osmosis separation of the aqueous biological fluids biochemical production is influenced by the flow rate of solvent and the mass transfer coefficient. Experimental study allowed to characterize that by using the process of reverse osmosis can effectively divided, clear, and contaravati industrial solutions biochemical industries. Data at a rate of detention allow to evaluate the influence of concentration polarization on the efficiency of the reverse osmosis separation of industrial solutions. As a result of systematization and evaluation of experimental data and dependencies at a rate of detention found that with increasing the concentration, the rate of detention of solutes decreases. Based on the analysis and modification of the proposed equation for theoretical calculation of detention. Theoretical description of the coefficient detention accurately adequately calculated the modified equation N. V. Churaev, B. V. Deryaguin and V. M. Starov. The numerical values of the empirical coefficients, to calculate and predict the odds of arrest for a similar membrane separation processes industrial solutions. Values obtained correlation coefficients. The correlation coefficients specify that the rate of detention has a strong inverse dependence on the concentration of the dissolved substance, which confirms the influence of concentration polarization on the coefficient detention membranes.

In this paper, we describe the results of the study of an MGA-95 semipermeable composite membrane with amorphous and crystalline regions, considering the effect of the three processes migration, diffusion and fluid convection of solute and solvent. It was found that during swelling the supramolecular structure of the membrane material undergoes changes caused by deformation of the crystalline and amorphous regions of the membrane sample. The data on the amorphous regions for air-dry, water-saturated and working semipermeable membrane samples were analyzed. The comparative analysis of the diffraction patterns of an MGA-95 membrane showed that the external impact does not change the intramolecular structure of the membrane. Using the experimental data and the method of small-angle X-ray scattering we calculated the size of pores for MGA-95 and ESPA composite membranes. The findings led to the conclusion about the relative uniformity of the pore distribution in the thickness of the active layer of the membrane, and made it possible to determine their configuration. The data on the pore structure morphology of semipermeable membranes indicated that sorption region of MGA-95 and ESPA membranes was formed by pores of different types with varied surface morphology; smaller radius pores had a smoother surface, while larger pores had a rough surface. The number of larger radius pores -12.9 and 16.8 nm were equal to 20 and 35.6 % for MGA-95 and ESPA, respectively. Specific surface values for MGA-95 was S sp = 9.15 × 107 m-1 and for ESPA it was S sp = 5.95 × 107 m-1.

The paper presents experimental study of physical water condition and mass transfer in cellulose acetate and dynamic semipermeable membranes by infrared spectrometric and hydrodynamic methods. The authors found that OH-groups of cellulose acetate form a nonequilibrium grid of hydrogen bonds between molecules and their fragments in the amorphous phase of the semipermeable membrane in the air-dried sample. The water molecules adsorbed on active —OH and —C = O groups, particularly in the amorphous phase, create additional negative charge on the molecules of cellulose acetate resulting from the orientation of the water dipoles, which leads to electrostatic repulsion of broken, stranded molecule fragments and straightening of polymer molecule while breaking intermolecular hydrogen bonds. Thermogravimetric studies to find out the structural organization of hydrogen bonds and water condition in the samples of the semipermeable polymeric MGA-95 membrane showed that at temperatures in the air-dry and water-saturated samples the membrane degradation process starts and ends with mass loss and endothermic effect. The research proves the fact of dynamic membranes formation on the ultrafilters from water starch solutions. Due to the changes in condition and volume of water in the dynamic layer of the membrane, it is possible to change kinetic coefficients, i.e. to regulate the process of baromembrane separation of industrial water solutions. Electro-kinetic characteristics of reverse osmosis semipermeable membranes were studied. The experimental curves of the potential depending on sorption of sodium bicarbonate by MGA-95 and LSA-100 membranes were obtained. The discrepancy between the calculated and experimental data did not exceed 10 %. The method devised for determining the membrane potential in the process of sorption of sodium bicarbonate can be used as a testing methodology of polymeric semipermeable membranes.