JPH02139008A - Cleaning method for filter - Google Patents

Abstract

PURPOSE:To clean a filter, even when washing fluid is introduced with small flow velocity, in a short period of time almost completely by introducing a grain material into a filter layer fixed to a filter together with the washing fluid and cleaning the same. CONSTITUTION:A filter 1 is formed by disposing a filter layer 3 fixed in a filter main body 2, and a filter medium of large void content is filled in the filter layer 3. A grain material 4 is stored in a bottom section of the filter main body 2 during filtering operation, and washing fluid 7 is introduced from the lower section of the filter main body when a filter layer 3 is cleaned. The grain material 4 is flown up by the upward flow of the fluid 7 to be cleaned and fluidized in a filter main body 2 including the filter layer 3, and the fluid 7 only forms cleaning drain 8 to be drained out of the front section of the main body 2. The grain material 4 is collided with the filter medium filled in the filter layer 3 to peel off suspended solids of the filter layer 3.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a four-layer cleaning method for a filter having a fixed filter layer, and particularly to the filter for treating organic wastewater such as urban sewage and industrial wastewater. A method suitable for cleaning four layers of.

[Prior Art] When removing suspended solids (hereinafter referred to as ss) from water or wastewater, the water to be treated is filtered using a filter filled with a filter material to form a filter layer. is being carried out. In this filter, the filter layer becomes clogged due to the capture of SS, so it is necessary to wash the filter layer every time a certain filtration time elapses. To wash the filter layer, use water and water from below the filter layer.
Cleaning fluid such as water and air is supplied, and the 5
This is carried out by a method in which St- is peeled off, suspended in a cleaning fluid, and discharged together with the cleaning fluid.

[Problem to be solved by the invention] When cleaning a filter layer, if the filled filter medium is a granular filter medium, the filter medium particles move or flow due to the upward flow of the cleaning fluid, and the filter medium particles become separated from each other. SS adhering to the filter medium is easily peeled off due to repeated rubbing and collision. However, if the filter layer filled with filter media is fixed,
Even when cleaning fluid is supplied, the filter media does not move substantially.
Therefore, cleaning of the filter medium in this case is performed only by the energy of the cleaning fluid.

Therefore, if the filter layer is fixed, cleaning the filter layer requires a long time. Further, since cleaning is performed using only the energy of the cleaning fluid, the flow rate of the cleaning fluid must be increased, and therefore a large amount of cleaning fluid is required. Furthermore, in such washing, the filter layer may sometimes be insufficiently washed. If the filter layer is not washed sufficiently, the attached SS will stick and become difficult to remove later.
Partial blockage of the filter layer may cause a biased flow of the water to be treated, reducing filtration efficiency. Furthermore, SS stuck to the filter medium may ferment and generate gas, reducing the SS removal rate. This may cause corrosion of the equipment and generation of bad odors.

The present invention solves the problems of the prior art in filters with a fixed filter layer, reduces the cleaning time of the filter layer, uses less cleaning fluid, and almost completely cleans the filter layer. The purpose of the present invention is to provide a filter cleaning method that enables the cleaning of filters.

[Means and effects for solving the problem] In order to achieve the above object, in the method of the present invention, in a method for cleaning a filter layer in a filter having a fixed filter layer, particulate particles are added to the filter layer together with a cleaning fluid. to wash the filter layer.

At this time, the introduced particulates may be allowed to flow while remaining in the filter layer to wash the filter layer, or the introduced particulates may be passed through the filter layer together with the cleaning fluid and discharged from the filter body. The filter layer may be washed while collecting the discharged particulate matter and circulating it within the filter main body.

The cleaning method of the present invention is applied to a filter in which a filter layer is formed by filling a filter medium with a larger porosity than a general filter medium, and the filter layer is fixed. Then, particles are caused to collide with the filled filter medium, and SS adhering to the filter medium is peeled off by this collision energy. The flow rate of the cleaning fluid passing through the filter body during this cleaning is approximately 40 to 100 m/hour when the cleaning fluid is water only, and when air and water are supplied separately and cleaning is performed in the order of air and water. The flow rates of air and water are approximately 30 to 100 m/hour and approximately 30 to 100 m/hour, respectively. In addition, when water and air are supplied at the same time, the flow rate is approximately 50 to 200 m/hour.

Granular materials such as natural materials such as sand and anthracite, inorganic composite materials such as metal powder and ceramics, and synthetic resin grains have abrasion resistance and do not change in quality due to the water being treated. Select one that does not contain eluted components.

The type, specific gravity, particle size, etc. of the granular material are determined as appropriate depending on the cleaning conditions. Among these, the particle size of the granules is determined by the flow rate of the cleaning fluid, and is usually set to the size shown in Table 1.

The particle sizes listed in Table 1 indicate the values in which the flow velocity of the cleaning fluid is within the following range.
/hour, when water and air are supplied at the same time, the flow rate based on the total amount is 70 to 100 m/hour, and when air and water are supplied separately and the air and water are washed in that order, the flow rate is 30 to 70 m/hour.
/It is time.

Table 1 Example of particle size of granular material (Dragon) The amount of granular material introduced into the filter layer is 1 to 10% of the filter layer volume.
The amount is appropriate, preferably about 3 to 7%.

[Example] FIGS. 8 to 10 are diagrams schematically showing a part of a filter medium filled in a filter to which the cleaning method of the present invention can be applied.

The filter medium 20 in FIG. 8 is made of vinylidene chloride, polyethylene,
Water-resistant fibers 21 such as synthetic fibers such as vinyl chloride or metal wires such as stainless steel are coated and bonded with a binder to form a non-woven structure into a rectangular parallelepiped or cube having a three-dimensional mesh-like structure. The diameter of the water-resistant fibers 21 constituting the filter medium 20 is in the range of 100 denier (approximately 0.091 mm) to 10,000 denier (approximately 0-0-91 a), and the porosity of the filter medium 20 is 90% to 99. The porosity is in the range of 5%. This porosity is within a range where particulates can easily pass through or flow during cleaning of the filter, and the removal rate of SS does not decrease. This filter medium 20 forms a filter layer. The method is to fill a filtration tower so as to cover it all over to form a fixed bed.

Each filter medium 20 in FIG. 9 is formed from various filter medium materials into a cylindrical shape. As the filter medium material, the la1 diagram shows the 7th
Like the filter medium shown in the figure, it is made of non-woven water-resistant fibers, and the figure (b) is made of metal wire or single fibers of synthetic resin woven into a woven form. Further, IC1 diagram shows a metal plate or a synthetic resin plate provided with a large number of pores. These filter media are used by being packed regularly or irregularly in a filtration tower.

The filter material in Figure 10 is the filter material 2 in the fat diagram and fb1 diagram.
2 is assembled as shown in the IC1 diagram. The filter material 22 in the figure (a) is a woven metal wire or single fiber of synthetic resin, and the filter material 22 in the tbt figure is a metal plate or a synthetic resin plate provided with a large number of pores. (
C) The figure shows a cross section of the assembled filter medium, 22 is the above-mentioned filter medium material, 23 is a holding frame for the filter medium material, and holding frame 2
3 forms the filter medium 20 by sandwiching the filter medium material 22, and the thickness of the filter medium 22.
It plays the role of a spacer that determines the distance between 22. By changing the thickness of this holding frame 23, filter media 20 with different porosity can be obtained. This filter medium 20 is spread and packed inside the filter tower.

Hereinafter, a method for cleaning a filter filled with a filter medium having a very high porosity as described above will be described.

FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1, 1 is a filter equipped with a filter M3 fixed in the filter body 2, and the filter layer 3 has a filter medium with a large porosity as shown in FIGS. 8 to 10. Filled. 4 indicates granular materials such as sand, anthracite, and synthetic resin particles, 5 indicates water to be treated, 6 indicates filtered water, 7 indicates cleaning fluid (water or water and air), and 8 indicates cleaning wastewater. is the state in which the filtration operation is being performed, lb1 is the state in which the filter layer is being washed, f
Figure c1 shows a state in which cleaning of the filter layer has been completed. In Figure (a), particulate matter 4 is stored at the bottom of the filter body 2 during the filtration operation. (b) In the figure, when the cleaning fluid 7 is introduced from the lower part of the filter body 2, the particulate matter 4 is removed by the cleaning fluid 7.
The cleaning fluid 7 is blown up by the upward flow and flows inside the filter body 2 including the filter layer 3, and only the cleaning fluid 7 becomes cleaning waste water 8 and is discharged from the upper part of the filter body 2. Due to this flow, the particulate matter 4 collides with the filter material filled in the filter layer 3, and the S of the filter layer
S peels off. The peeled SS is suspended in cleaning waste water 8 and discharged. In the figure (C), when the introduction of the cleaning fluid is stopped, the particulate matter 4 settles to the bottom of the filter body 2, and the filtering operation can be started. This method uses granules that have a relatively high settling velocity. In addition, cleaning drainage 8
Some particulate matter will be mixed in, so this particulate matter will be collected separately and the particulate matter equivalent to the amount lost will be replenished.

FIG. 2 shows a second embodiment of the invention, in which the method of FIG.
FIG. 3 is a diagram showing a method with additional steps.

In the description of this embodiment, the same reference numerals will be given to the parts already explained in FIG. 1, and the explanation will be omitted. In FIG. 2, (a) is a state in which a filtration operation is being performed, a TBT diagram is a state in which the filter layer is being washed with only cleaning fluid, and an IC1 diagram is a state in which particulate matter is introduced and the filter layer is being washed. Figure Ta2 shows the state in which cleaning of the filter layer has been completed.The process added to the method in Figure 1 is the process in Figure b1.
The cleaning fluid (Mizushima or water and air) 7 is introduced from the bottom of the filter body 2 located above the storage part of the particulate matter 4 while the water is stored at the bottom of the filter body 2. The cleaning fluid 7 cleans the filter layer 3 without causing the particulate matter 7 to flow, and is discharged as a cleaning waste water 8 containing the separated SS. It is relatively easy to wash the filter layer in the early stages of washing, and the effect of introducing a single particulate material is noticeable in the intermediate or final stages of washing.

Therefore, SS can be peeled off to a certain extent in a relatively short time using only the cleaning fluid. For this reason, the step shown in Figure tb1 above is added. The method including this step is suitable for cleaning a filter layer to which a large amount of SS has adhered.

FIG. 3 shows a third embodiment of the present invention, and is a diagram showing a method in which two more steps are added to the method of FIG. 2 and the cleaning fluid in one step is changed.6 In the description of this embodiment, , the parts already explained in FIG. 2 are designated by the same reference numerals and the explanation thereof will be omitted. In Fig. 3, (a) shows a state in which the filtration operation is being performed, and tb1 shows a state in which the filter layer is being washed with only the washing fluid.
+C1 figure is the state where particulate matter is introduced and the filter layer is being washed, td
Figure 1 shows the state where the filter layer is left standing, tel shows the state where the filter layer is being washed with only cleaning fluid, and ffl shows the state where the filter layer has been washed. [2
This is the process shown in Figure 1, and the process in which the cleaning fluid was changed is the process shown in Figure fc1.

In Figure Ic1, while the particulate matter 4 is stored at the bottom of the filter body 2, only air is introduced as the cleaning fluid 7 from the bottom of the filter body 2 located above the storage part of the particulate matter 4, and in Figure fb1. The SS that could not be removed in step 2 is peeled off from the filter layer. In this case, since the introduced cleaning fluid 7 is only air, the 2SS remains in the filter body 2. In the figure (d), the introduction of the cleaning fluid is stopped and the filter is allowed to stand still, allowing the particulate matter 4 to settle to the bottom of the filter body 2. At this time, the SS separated from the filter layer 3 remains in a floating state. In the figure (e), only water is introduced as the cleaning fluid 7, and the SS peeled off mainly in the step of Figure Ic1 is suspended in the cleaning waste water 8 and discharged. The cleaning fluid 7 cleans the filter layer 3 without causing the particulate matter 7 to flow, and is discharged as a cleaning waste water 8 containing the separated SS. It is relatively easy to wash the filter layer in the initial stages of washing, and the effect of introducing a single particulate material is noticeable in the intermediate or final stages of washing. Therefore, SS can be peeled off to a certain extent in a relatively short time using only the cleaning fluid. For this reason, the step shown in the +bJ diagram above is added. The method including this step is suitable for cleaning a filter layer to which a large amount of SS has adhered. According to this method, the cleaning waste water is not discharged with the particulate matter still flowing, so there is no outflow of the particulate matter, and operations such as collection and replenishment of the particulate matter are not necessary.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.1 In the explanation of this embodiment, the same reference numerals are given to the parts already explained in FIG. 1, and the explanation will be omitted.0 This embodiment The filter 1 is provided with a particulate material circulation means 9 consisting of a particulate material separator 10, a particulate material storage tank 11, and an accompanying flow path.

(a) Figure shows the state in which the filtration operation is being performed, Figure fb1 shows the state in which the filter layer is being washed, and Figure Ic1 shows the state in which the cleaning of the filter layer has been completed. 4 are stored in a storage tank 11 of the particulate circulation means 9. (b) In the figure, the valve 12 of the particulate matter circulation means 9 is opened and the particulate matter 4 is removed.
is caused to flow into the filter body 2, and at the same time, the 1 filter body 2
The particulate matter 4 passes through the four layer 3 together with the cleaning fluid 7 and enters the separator 10 while the particulate matter 4 and the cleaning fluid 7 pass through the filter layer 3. The particulate matter 4 collides with the filter medium filled in the filter layer 3, and the SS of the filter layer is separated.In the separator 10, the particulate matter 4 is sedimented and separated and sent to the storage tank 11, while the water of the cleaning fluid 7 is separated from the SS of the filter layer. is discharged as cleaning wastewater 8 containing In the figure (C), at the end of cleaning, the valve 12 is closed while the cleaning fluid continues to flow, and the particulate matter 4 is collected and stored in the storage tank 11. This method uses granules that have a relatively low settling rate.

FIG. 5 shows a fifth embodiment of the present invention, in which the method of FIG.
FIG. 3 is a diagram showing a method with additional steps.

In the description of this embodiment, the same reference numerals are given to the parts already explained in FIG. 4, and the explanation will be omitted. In Figure 5, the fat diagram shows the state in which the filtration operation is being performed, the tb1 diagram shows the state in which the filter layer is being washed with only cleaning fluid, the +C1 diagram shows the state in which the filter layer is being washed by introducing particulate matter, and the td1 diagram 1 shows the state in which the cleaning of the wave layer has been completed. The step added to the method of FIG. 4 is the step of lb1.

In Figure lb1, a cleaning fluid 7 is introduced from the bottom of the filter main body 2 while the granules 4 are stored in the storage tank 1. The cleaning fluid 7 cleans the wave layer 3 and is discharged as a cleaning waste water 8 containing SS separated by i11. This method, like the methods shown in FIGS. 2 and 3, is suitable for cleaning a wave layer to which a large amount of SS has adhered.

Next, the results of cleaning a filter using the method of the present invention will be explained.

(Example) A filter having a diameter of 10 cIl and a height of 2.5 m was filled with the filter medium shown in FIG. 7. The conditions for the filled wave layer were as shown in Table 2. 5S165~ for this filter
Filter raw sewage containing 200 lIg/II at a filtration rate of 120
Water was continuously passed for 24 hours at a rate of m/day for filtration. The SS removal rate in this filtration was on average 85%, and the amount of SS trapped in the wave layer was approximately 19 kg/m''.

Conditions for the second surface wave layer Table 3 Cleaning conditions The wave layer to which SS was attached was cleaned under the conditions shown in Table 3. Note that sand was used for cleaning in which the granules were made to flow in the filter layer, and synthetic resin particles were used in the cleaning in which the granules passed through the wave layer. The results of this experiment are shown in Figures 6 and 7.
In Figures and Figure 7, 0 indicates when the granules are sand and are washed by flowing in a fluid bed, Δ is when the granules are synthetic resin particles and are washed by passing through a wave layer, and . is when no granules are added. This is the case.

FIG. 6 shows a case where the flow velocity of the cleaning fluid is 40 m/hour. As is clear from Figure 6, when granules were added, 99% of the SS adhering to the filter layer was peeled off and recovered within 10 minutes of washing, whereas when no granules were added. Even after 20 minutes, only about 93% of the amount was recovered, and it would take a longer time to administer the wave layer intravenously. As described above, according to the method of the present invention, the wave layer can be cleaned in an extremely short time. In addition, as in this experiment, even if the cleaning fluid is introduced at a small flow rate, the cleaning can be completed in a short time.There is a case where 0 particulates are washed by flowing in the filter layer, and a case where it is washed by passing through a wave layer. There was no difference between the two.

FIG. 7 shows a case where the flow velocity of the cleaning fluid is 50 m/hour. As shown in Figure 7, the difference between the method of the present invention and the method without the addition of particulate matter was remarkable. In the method of the present invention, the time required to recover 99% of the SS attached to the filter layer was 8 minutes. On the other hand, the method without the addition of particulates required 20 minutes, which was more than double the cleaning time.

[Effects of the Invention] The present invention is a method in which particulate matter is introduced together with a cleaning fluid when cleaning a filter to which a wave layer is fixed, and the SS attached to the filter medium of the wave layer is peeled off due to the collision of the particulate matter. Therefore, even if the cleaning fluid is introduced at a small flow rate, the wave layer can be cleaned in a very short time and can be almost completely cleaned.

Therefore, the amount of water and compressed air used as cleaning fluids is reduced, the processing cost for filtration is reduced, and the operating rate of the filter is improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a first embodiment of the present invention, Fig. 2 is a diagram showing a second embodiment of the invention, Fig. 3 is a diagram showing a third embodiment of the invention, and Fig. 4 is a diagram showing a third embodiment of the invention. FIG. 5 is a diagram showing a fifth embodiment of the present invention, FIGS. 6 and 7 are explanatory diagrams of the results of a cleaning experiment using the method of the present invention, and FIGS. 8 to 10 1 is a diagram schematically showing a part of a filter medium filled in a filter to which the cleaning method of the present invention can be applied. 1... Filter, 2 Filter body, 3... Filter layer, 4-...
... Granular matter, 5... Water to be treated, 6... Filtered water, 8.
...Washing waste water, 9.. Particulate matter circulation means, 10.. Separator, 11.. Storage tank, 20.. Filter medium.

Claims (3)

[Claims] (1) A method for cleaning a filter layer in a filter having a fixed filter layer, characterized in that the filter layer is washed by introducing particulate matter into the filter layer together with a cleaning fluid. (2) The method for cleaning a filter according to claim 1, characterized in that the particulate matter introduced into the filter layer is made to flow in the filter layer. (3) In the method for cleaning a filter according to claim 1, the particulate matter introduced into the filter layer is passed through the filter layer together with the cleaning fluid and discharged from the filter body, and the discharged particulate matter is collected and removed from the filter body. A method for cleaning a filter, characterized by circulating the air within the main body.