SU1114439A1 - Method of regenerating filtering layer made of elastic porous material - Google Patents

Abstract

1. METHOD FOR REGENERATING A FILTER STRUCTURE FROM A ELASTIC POROUS MATERIAL, including the expansion of the layer and the supply of air into it from the bottom-up and the washing water, characterized in that, in order to improve the quality of regeneration and reduce the consumption of wash water, the washing water is fed before filling the filter layer and then a pulsed air supply with an intensity of 100-200 l / cMf is carried out. 2. The method according to Claim 1 is also characterized in that the air is supplied with a frequency of 4-15 minutes. (L with

Description

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The invention relates to oil and water from suspended substances of products and can be used in the treatment of industrial wastewater and polluted rainwater runoff from cities and industrial enterprises. Filtration through porous elastic polymeric materials is one of the promising areas of natural and wastewater treatment. At present, the use of flexible polyurethane foams is most effective in filtration purification of water containing suspended solids and petroleum products. Polyurethane foam filters are much better than filters with a load of sand, gravel, anthracite in terms of productivity, capacity, achieved quality of filtrate. However, the regeneration of the filter charge, i.e. restoration of its filtering ability. The choice of the method of regeneration of the filtering material largely determines the effectiveness of the use of polyurethane foam filters. The regeneration of elastic materials is especially complicated when there is a high content of both suspended substances and oil products in the water being treated. There is a known method of regenerating a polyurethane foam load by backwashing it with hot water in combination with periodic mechanical compression of the charge. This method allows to achieve a rather high effect of washing the load from the delayed impurities of the SP. However, with this method of regeneration, there is no possibility of expanding the filter charge and mixing it, which causes a significant duration of soil removal and a large consumption of rinse water. The closest to the invention is a method of regenerating a filtering load from crushed polyurethane foam, including pre-expansion of the load twice, blowing air at a flow rate of 14-16 l / cm for 5 minutes and subsequent water-flushing for 12-15 minutes at 391 air is supplied from below with the same intensity, and water from above with intensity of 1214 l / cm. This method is relatively simple and is used to flush a load of 4-6 mm in size in filters designed for the purification of biochemically treated wastewater containing 15-35 mg / l of flocculent suspensions. Under such filtering conditions, the contamination is retained mainly on the rough surface of the loading particles, the soil capacity of which in this case is 6.8-9.6 kg / m, and the method used for regenerating the raw material is quite effective C2. The disadvantage of the known method is that even with a significant specific consumption of wash water, there is no noticeable effect of washing the polyurethane foam load used in other filtering conditions, for example, after purification of industrial and rainwater that has undergone mechanical cleaning and containing 100-300 mg / l and more dispersible granular impurities, as well as petroleum products. The low effect of flushing the load is due to the fact that polyurethane foam in such filters is used in the form of relatively large particles (10-20 mm). The dispersed impurities of the treated water are retained mainly in the pores of these particles. a rather solid sediment accumulating in a significant amount (the loading capacity is 50 kg / m or more). When these filters are rinsed with the existing method, the filter material remains stationary, and a noticeable effect of washing the soil is not achieved (does not exceed 20-30%). The purpose of the invention is to improve the quality of regeneration and reduce the consumption of wash water. % This goal is achieved by the fact that according to the method of regenerating the filtering layer of elastic porous material, including the expansion of the layer and the supply of air into it from the bottom upwards and the washing water, the washing water is supplied until the filtering layer is filled with an intensity of 100 200 l / cmH 3 In addition, the ray air supply is carried out at a frequency of A-15 min. The proposed method differs from that known in the air intake mode. In the known method of regenerating a polyurethane foam load, air is supplied continuously with the intensity normally used in sand filters (14-16 l / cm). In this mode of introducing air, the filter layer during the washing process remains stationary, and the removal of sediment from the depth of the pores of the particles of filter material practically does not occur. A significant increase in the intensity of the continuous supply of air (5-7 times) provides the necessary expansion of the filtering load. Moreover, with a continuous supply of air, the expansion of the load occurs in the first seconds, then its volume stabilizes, air barbates through the load, providing noticeably mixing of the load particles and improving their lifting conditions only in the upper zone 0.2-0.5 m high. With further increase The intensity of the continuous air supply is established by the jet mode of the air distribution system, the air is released in the form of large bubbles that occupy almost the entire cross section of the filter, which creates a piston-like mode. or download. According to the proposed method of introducing air with high intensity (more than 100 l / cm) short pulses lasting 0.53 seconds with a pause the mezscu they leads to a sharp pulsating expansion of the filter layer of 0.2-0.5 m in height, which leads to intensive to the displacement and impact of the particles of the charge, ensures the destruction and transition to the liquid phase of the sediment accumulated in the pores of these particles during filtration. The duration of the movement of the particles of the charge after each air supply pulse is determined by the duration of the ascent, forming the pshhs large bubbles in the filter layer. The lifting speed of such bulls in the water-filled polyurethane foam load is 94 average 0.2 m / s. With a height of 0.5–2.5 m advanced in the process of regeneration of the filtering layer, the duration of the blasting of bubbles through the loading and its mixing at the same time after the next air supply pulse is completed within 3–12 s. Taking into account the duration of the air supply pulses and the damping of its effects on the loading, the interval between the pulses is taken within 4-15 seconds, and the frequency is within 415 minutes. In this mode of mixing, the maximum concentration of impurities in the wash water, depending on their content in the filter loading, within 1-2 minutes At such intervals, the wash water in the filter should be replaced. The drawing shows the filter in which the regeneration of the loading is carried out. The filter consists of a housing 1, equipped with a lower 2 and an upper 3 with perforated horizontal fixed partitions, a movable horizontal perforated partition 4 with a drive for its vertical movement 5, an annular tray 6 for collecting purified water, a cone-shaped bottom 7. Between the partitions 2 and 3 there is crushed elastic porous material 8 (for example, polyurethane foam with a particle size of 10-20 mm). Pipeline 9c is connected to housing t with valves 10 and 11 for supplying the liquid to be cleaned to the filter, pipeline 12 for discharging purified water; piping 13c with a valve 14 for discharging wash water; pipeline 15c with valve 16 and automatic pneumatic distributor 17 for pulsed delivery of compressed air. On the upper planes of partitions 2 and 4 there are accommodations for distributing compressed air, respectively, 18 and 19, while fixture 18 is directly connected to the compressed air supply pipe 15, and fixture 19 - using vertical telescopically articulated nozzles 20. Partitions 2 and 3 connected by vertical rods 21, which serve as guides for the movable partition 4. The movable partition of the dream is bounding the lowermost 22 and KpaftHefo of the upper 23 position for which can be used types of limit switches. The guide rods are made with perforated floors below the extreme upper position of the movable partition and also serve as air pipes for venting air from the lower cavity of the filter during its regeneration. Example. Sewage water with a dispersion of 500 l / h and a content of dispersed impurities of 100 mg / l is piped by conduit 9 with open valve 10 and fed to a filter model loaded with crushed polyurethane foam with a particle size of 10 mm. The diameter of the filter is 0.2 m, the height of the filter layer is 1.5 m, the loading weight is 2, 4 kg (1.2 kg each in the upper and lower cavities of the filter). The movable n partition 4 is set 10 cm above the middle position, which ensures a reduction in the pore size in the filter material in the direction of filtration. After the completion of the filter-cycle, determined according to the analysis of purified water, the valve 10 is closed, the filter is emptied through line 13 with the valve 14 open and the filter charge is regenerated. To do this, the movable partition 4 is transferred to the lowest position (shown in the bottom dotted line) by the actuator 5 until the limiter 22 triggers. After that, the filter layer in the upper cavity of the filter is filled with purified water through pipeline 9 with the valves 10 and 11, then the valves 10 and 11 are closed, the valve 16 is opened and, by means of the pneumatic distributor 17, air is pulsed through the connections 20 into the device; 19. The duration of the air supply pulse is 1.5 s, the intensity is 200 l / cm, the duration of mixing the load with air is 1, 5 minutes, the frequency of the spirit supply pulses is equal to 7.5 minutes. Such air bubbles formed at the air intake impulse at a given height of the expanded filtering layer had time to sit on the loading surface before the next air supply impulse. After washing the load in the upper cavity of the filter, the valve 16 is closed, and the movable partition 4 is moved to the uppermost position (in the figure shown by the upper dotted line) until the limiter 23 is pressed and the washing water is pressed. from laundered download. Wash water is removed through conduit 13 with open valves 11 and 14. After that, valve 11 and 14 is closed and through pipe 9 with open valve 10, the filter layer of the lower cavity of the filter is filled with water to be cleaned. The valve 16 is opened and, with a pulsed air supply to the device 18, the load is washed in the lower cavity of the filter for its distribution. Next, the valve 16 is closed, and the valve 14 is opened, the partition 4 is moved to the lower position, pressing the wash water from the load in the lower cavity of the filter. Thereafter, the wash cycle of the loading in the upper and lower cavities of the filter is repeated. The regeneration is stopped when the concentration of impurities in the wash water becomes close to that in the treated water. Limiters 2-2 and 23, associated with the vertical movement drive of the movable partition 4, are set from the condition of compressing the filter charge to a density of 200-250 kg / m. The vertical movement drive of the movable partition 4 is selected so that its vertical speed does not exceed 0.05 m / s. At higher speeds and compression ratio, the required drive power increases, the washing water is difficult to remove from the load, the loss is accelerated elasticity and porosity of polyurethane foam particles. In order to obtain comparable data on the filter models of the proposed design, the filtering conditions are the same in all experiments (water feed rate, initial impurity concentration in the water being cleaned, filter duration), which provides almost the same gravity load for

7 .1

filter cycle A series of experiments to establish the optimal parameters for the regeneration of the load and the comparison of the proposed and known methods are carried out in model filters when the filter media is filled with one (lower) filter cavity, which allows for comparative experiments on regeneration using both methods under the same conditions (in the same filter). The duration of one cycle of washing the load by the proposed method (filling the filter bed with cleaned water, mixing; air, removing the wash water) is about 5 minutes.

A series of experiments on the regeneration of loading under optimal conditions is also carried out in the filter model of the proposed design when the filter material is filled with both filter cavities.

The quality of regeneration or washing of the load in experiments is characterized by the number of residual contaminants and is expressed as a percentage of the total number of impurities retained for the filter cycle.

Experimental data are given in table. 1-4. The dependence of the quality of washing the load by the proposed method on the intensity of air supply at different durations of recovery, determined by the number of filter washing cycles, is presented in Table 1 (The load per filter cycle in the experiments was taken about 60 kg / m).

As follows from the above data, when the air supply intensity is less than 100 l / cm, the quality of the washing load is low, even with a significant regeneration time and increases dramatically with increasing intensity to 100 l / cm or more, when the effect is

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mixing load. At the same time, the air supply with an intensity of more than 200 l / cm practically does not lead to a further increase in

5 regeneration quality, but requires a more powerful source of compressed air. In this connection, the upper limit of the intensity of the air supply during the regeneration of porous elastic

10 filter loading is advisable to take no more than 200 l / cm.

The dependence of the quality of the washing load on the duration of mixing at various stages of regeneration is presented in Table 2.

The data obtained show that the duration of the mixing of the load of air in each cycle is about; washes. the proposed method should take 20 minutes at least 1 min.

Comparative data on the quality of regeneration of the known and proposed methods are presented in table 3.

As follows from the above data, the application of the proposed method allows to achieve a significantly higher effect of regeneration of the filter charge with approximately the same specific air flow rate and less than 2-3 times the flow of flush water.

Data on the regeneration of filter loading in the filter proposed

35 constructions (with two cavities) are listed in Table 4.

Thus, the use of the proposed method of air

The Q flushing of filters with porous elastic loading allows an increase in the duration of the filter cycle and, consequently, filter performance, due to an increase in quality.

45 washing of the load from the retained contaminants, and reduce the consumption of wash water.

ten

1114439

T a 5 l and c a 1

C regeneration duration, min

The intensity of the air supply, l / cm2

Table .3

20

20 16

200

Regeneration Process Indicators

Regular regeneration, min

Intensity

air supply

l / cm2

Washing effect

load%

Air flow

on 1 l of loading, l

Water flow

1 liter of load, l

Table 4

Value of parameters

r2

Claims (2)

1. METHOD FOR REGENERATING A FILTER LAYER FROM AN ELASTIC POROUS MATERIAL, including expanding the layer and supplying air in it from the bottom up and rinsing water, characterized in that, in order to improve the quality of regeneration and reduce the flow rate of rinsing water, the rinsing water is supplied before filling filter layer and then carry out a pulsed air supply with an intensity of 100-200 l / s And *. 2. The method according to claim 1, on behalf of the fact that the pulse air supply is carried out with a frequency of 4-15 minutes ”!