Modernisation of filter design with bulk dispersed media

. The object of research in this article is the design of the filter with bulk dispersed media; this type of device has a wide application within the framework of water treatment for technological needs of food enterprises. On the basis of the data of the previously obtained complex of theoretical and experimental studies of the process of bulk filtration of mechanically activated aqueous solutions, the main purpose of the work is to find effective options for modernisation of the filter design with bulk dispersed media, allowing one to improve the filtration process, namely to increase productivity and improve the quality of filtrate. The research methods included both theoretical (methods of analysis, comparison, etc.) and experimental measures aimed at studying vibromechanical activation of the initial solution in the process of filtration, studying the physical and chemical properties of the activated solution, and determining the rational modes of mechanical action. The results obtained in the course of the research are determined by the basis of the modernisation of the device, the changes made in the design had a positive effect on its operation, and the cycle time changed by 20-22 %. The achievements of the device modernisation are represented by: built-in vibromechanoactivators; washing and regeneration without the use of reagents; measurement by sensors of indicators in the device tanks before and after the filtering process; improved wear resistance and durability of the casing coating inside and outside. On this basis, further plans are focused on the realisation of the design ideas into an experimental industrial unit and subsequent research in laboratory and industrial conditions


Introduction
Comprehensive analysis of the study results of domestic and foreign scientists I.G.Bereza, M.A. Vashchenko, E.N. Kal'sina, V.A. Klyachko, G.A. Pankovskiy, V.V. Sapozhnikov, N.K. Khristoforova, N. Ueki, Z. Ikeda, etc., as well as the experience of processing of hydrobionts (of fish and non-fish origin) at fish processing enterprises of freshwater and sea type have shown that one of the most important stages is water treatment, which allows removing foreign impurities from water, representing suspended (roughly dispersed), colloidal and dissolved state (Table 1).The main mass of insoluble impurities (from coarse particulate matter to microheterogeneous colloidal dissolved substances and high-molecular humus compounds) are removed from water as a prerequisite for its preparation for technological needs of fish processing plants.At the same time such organoleptic indicators as turbidity and transparency are improved.At present, various methods and devices for filtering (as coarse and fine purification) are widely used by fish processing enterprises for water treatment.In practice, multilayer bulk filters with multidisperse filtering granular materials of natural and/or artificial origin (Figure 1), laid in layers on a separating partition, have proved their efficiency.They have a large contact surface with solutions and adsorb macromolecular structures [1].
The selection of bulk dispersed media is guided by the factors shown in Figure 2. The cycle time of one washing varies for different materials.Figure 3 shows a histogram with the filter cycle time of the most used granular materials.
Obtaining of filtrate of advisable quality, as well as the reliability of this type of filters, depends not only on the characteristics of the bulk dispersed medium, but also on a number of other factors that determine those or other envisaged design capabilities of the device.-characteristics of the filter case material (the material from which the case is made must be resistant to the influence of the processed media on it, neutral, strong, durable, etc.); -the method of regeneration, which should ensure qualitative washing of the filter medium from accumulated contaminants (during a certain period of time during filtration the disperse material loses its barrier property to retain contaminants and thus there is a need for regeneration); -inclusion in the design of additional elements effective in reducing the rate of overgrowth of pores of granular loading (for example: vibration, pneumatics, etc.).However, unbalanced modes of exposure can adversely affect the economic feasibility and lead to increased energy consumption, complicating and weighing the device and others.
Based on these and many other factors there is a need to search for new alternative solutions to improve the efficiency of filtering devices.The authors in the process of scientific research came to the conclusion that it is necessary to apply mechanoactivation (mechanical impact) on the initial water solutions during filtration: -bottled water "Berdovskaya taezhnaya"; -aqueous salt solution NaCl (3.33 %); -complex water-salt-flour solution (with addition to 3.33 % salt solution -1 % of wheat flour of the highest grade); -distilled water with CaCO3 addition; -seawater (with salinity S over 35%о) etc.Preliminary experiments have shown that pre-mechanoactivation of solutions gives an increase in productivity (P, m/s) for 52-55 %, reduced filtering time (τ, s) for 44-46 %, amount of impurities (TDS, ppm) for 11-13 % (Figure 4), density reduction (ρ, kg/m 3 ) for 0.1-0.19%, viscosities (μ, Pa•s) for 4-6 %, surface tension (σ, N/m) for 15-17 % etc. purification of sea water [7] was carried out and rational parameters of its operation were determined.

Methods and materials
A filtering unit [6] was used as an object of research, the circuit diagram is shown in Figure 5. Data [7] were taken into account in the design, Figure 6 shows the circuit diagram of the device for seawater purification.The proposed constructions have a cylindrical body, both have seawater inlet and outlet spigots, and symmetrical rinse water inlet spigots.However, despite the initial similarity of designs and principle of operation, the devices have significant differences: -filter unit [6] (Figure 5) is a multilayer device having a control panel with an inbuilt potentiometer that regulates the frequency of vibration of the transmitted mesh partition by eccentric vibration motors; it also has four viewing windows with LED illumination built between them, this design has a more ergonomic stand; -seawater purification device [7] (Figure 6) is single-layer, the design includes pneumatic cylinders, a barboter, which leads to increased air consumption, complicates it, makes it heavier; it also has a temperature converter with a special temperature probe (to regulate the temperature of filtrate).
Based on design analysis of the devices and in accordance with the set goal, the basis for the next stage -modernisation of the device -is the theoretical and experimental experience accumulated by the team of authors of previous developments in the improvement of the filtering process and equipment.

Results and discussion
Figure 7 shows the design of filtering device with integrated vibromechanoactivators, which is a modernised version of an already existing installation [7].The device includes a cylindrical body (1) with upper (2) and lower reservoirs (3).In the upper part of the device there are built-in vibromechanoactivators (4) in the form of plate knives (this form of knives was selected experimentally, showing its efficiency), providing layer-by-layer vibrodispersing of liquids fed for filtration (e.g., sea water) together with impurities in them, at a speed of 2000 min -1 (Figure 8).
Taking into account aggressive properties of sea water, the case was treated inside and outside with special anti-corrosion paint.
The filter provides a spigot for feed of initial seawater (5) and filtrate discharge (6), symmetrical spigots for washing water discharge (7).In the inner part of the device layers of granular materials (8, 9) are poured on a mesh separating partition (10), with a sealing rubber contour (11), resistant to the effects of aggressive media.The device is equipped with a pair of string piezometers connected to a display for monitoring measurements (13), TDS, temperature, pH sensors (14) for monitoring the values before and after the filtering process.A control panel (15) is fixed on the upper tank, the unit is equipped with a lighting function, having a corresponding activation button on the control panel (16).
When it is necessary to regenerate the filter load, water is supplied under pressure through the symmetrical connections of the rinse water inlet (17).
The unit includes four observation windows (18), made of plexiglass in two layers, between which is built in LED illumination.The device is located on an ergonomic support (19).
The changes made in the design had a positive effect on the operation of the device.The cycle time has changed by 20-22 %.Pneumocylidrons, barboter, which led to increased air consumption, complication and cluttering of the design, maintenance and repair were excluded from the device design.

Conclusions
Thus, the proposed and introduced changes in the design of the filtering device are aimed at improving the filtering process, namely, allow to increase the productivity and improve the quality of filtrate.The main advantages of the improved device include: -built-in vibromechanoactivators provide a change in the properties of the initial solution (shear deformations (flow) in the layers are created, which leads to the breakage of intermolecular bonds, the internal energy of the system increases, surface tension and viscosity decreases, etc.).
-availability of washing and regeneration without the use of reagents, which reduces the consumption of washing water and filter media; -periodic measurement by sensors of parameters in the device tanks before and after the filtering process for operative monitoring of values (TDS, t, pH); -more wear-resistant and durable coating of the casing inside and outside, aimed at protection against external environmental influences.
In the search for alternative ways to improve the efficiency of bulk filtration of aqueous solutions, attempts were made to apply mechanoactivation and hydrophobic granular materials together.Experiments have shown a negative result, the throughput decreased (by 32÷34%) in comparison with the throughput when filtering unactivated aqueous solutions through layers of ordinary granular materials (by 39-41%) and through layers of hydrophobic materials.Also, in the process of filtration it was noticed that the density of filtrate after preliminary vibro-, vibromechanical activation increased (by 0,47-0,49%).Additional treatment with hydrophobiser inside the filter chamber did not work, because impregnation is not provided for metal surfaces, and this composition assumes porosity of the treated surface.
The proposed improvements allow to apply this device at the sites of water treatment for technological needs of fish processing enterprises, using sea water from the nearest water area and maximum approximation of production conditions to natural ones.
The conducted researches are directed on embodiment of constructive ideas in the experimental industrial installation and the subsequent carrying out of researches in laboratory and industrial conditions.

Fig. 2 .
Fig. 2. Factors to be taken into account when selecting granular materials for bulk filtration

Fig. 4 .
Fig. 4. Change in the amount of impurities (TDS)Thus, according to the results of the study of devices with separating bulk dispersed media and the analysis of data obtained during a series of experimental works on the study of mechanoactivation in the process of filtration of aqueous solutions (in laboratory and industrial conditions)[6] the work on modernisation of the design of the device for

Fig. 8 .
Fig. 8. Vibromechanoactivator oscillation amplitude at 2000 min-1 measured by the applications: a -Smart Vibration Meter; b -Smart Meter Pro, Vibration Eccentric vibration motors (12), transmit vibrations of different amplitude and frequency to the mesh separating partition (10), providing vibration laying, vibration lacing (necessary during regeneration) or vibration compaction of the layer (reducing its porosity).The device is equipped with a pair of string piezometers connected to a display for monitoring measurements (13), TDS, temperature, pH sensors (14) for monitoring the values before and after the filtering process.A control panel (15) is fixed on the upper tank, the unit is equipped with a lighting function, having a corresponding activation button on the control panel (16).When it is necessary to regenerate the filter load, water is supplied under pressure through the symmetrical connections of the rinse water inlet (17).The unit includes four observation windows (18), made of plexiglass in two layers, between which is built in LED illumination.The device is located on an ergonomic support (19).The changes made in the design had a positive effect on the operation of the device.The cycle time has changed by 20-22 %.Pneumocylidrons, barboter, which led to increased air consumption, complication and cluttering of the design, maintenance and repair were excluded from the device design.

Table 1 .
Phase-disperse characterisation of impurities according to L.A. Kulskiy