JPH10290905A - Method of filtering waste rice washing water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To meet the standards set for the discharge of waste rice washing water to sewerage by using a mesh filter of such a large mash that particles of maximum diameter of mixed particles in the waste water do not pass therethrough to filter the waste water. SOLUTION: Waste rice washing water containing mixed particles of 3 μto 1000 μ size is fed into a feed tank 1, and is drawn to an upper tank 3 through a pipe 3 by a drawing pump 2. In this state, the waste rice washing water in the upper tank 3 is sent into mesh filters 11 from a fall pipe 5. The waste rice washing water sent into the filters 11 is passed through meshes of the filters 7 and is returned to the feed tank 1. At the beginning, particles of large particle diameter mixed in the waste rice washing water are caught in the meshes of the filters 11. After that, however, by a capillary phenomenon in the particles, only water is passed through the filters 11 and is circulated as clean water. At this point of time, a switching cock 15 is switched so as to communicate with a drain pipe 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration method for draining rice sharpener drainage generated from a rice washing machine or the like to a public sewer so as to pass the drainage standard.

[0002]

2. Description of the Related Art Rice sharpening wastewater, which is the object of the present invention, generally has a very high BO of 3000-22000 ppm.
D (biological oxygen demand) and 70% of its wastewater
Up to 90% are SS components (suspended matter, mainly starch particles), the amount of dissolved BOD components is small, and most of them are rice starch particles of various sizes suspended and mixed in water. Furthermore, the specific gravity difference between the water in the waste water and the starch particles is small, and the precipitation alone cannot efficiently separate the starch particles from the water.

[0003] In order to discharge the rice juice drainage into public sewage, it must pass a drainage standard of 600 ppm BOD and 30 ppm normal-hexane extract, and when it comes to river discharge, 100 ppm BOD and 20 ppm normal-hexane extract. Wastewater standards and require secondary treatment.

Conventionally, rice sharpener wastewater is filtered by a centrifugal separator or a sedimentation filtration method in order to meet the above-mentioned wastewater standard, but it requires a large-scale apparatus, and is very expensive and uneconomical. There were difficulties.

[0005]

DISCLOSURE OF THE INVENTION The present invention proposes a filtration method which can economically drain rice sharpening water generated from a rice washing machine or the like with simple equipment, and which at least meets the criteria for discharging into public sewage. The purpose is to do.

[0006]

In order to achieve the above object, a method for filtering rice sharpening wastewater according to the first aspect of the present invention comprises:
A method for filtering rice sharpening wastewater containing mixed particles of 3 microns to 1000 microns in size, using a stitch filter having a large stitch size such that the largest particle of the mixed particles contained in the wastewater does not pass. And the waste water is filtered.

[0007] In the present invention, the reason that the particles mixed in the rice sharpening wastewater is limited to 1000 microns or less is that the sharpening juice comes out through a mesh of about 1 mm of the rice washing machine and is 1000 microns or more. Is not included in the rice sharpening wastewater. The reason for limiting the particles to 3 microns or more is that particles of 3 microns or less are hardly contained, and particles of 3 microns or less have almost no effect of increasing the BOD amount, which is the object of the present invention. Because.

According to the present invention, most of the rice sharpening drainage is S
S component (suspended matter, mainly starch particles), dissolved B
Focusing on the fact that rice starch particles of various sizes are suspended and mixed in water, with a small amount of OD components, and rice starch fine particles with a particle size of several microns to several hundreds of microns are selected. It is characterized by performing adsorption filtration with a stitch filter having a large size. That is, for example, the rice juice drainage is passed through a filtration filter having a mesh of about 100 microns, and particles having a particle diameter of 100 microns or more are caught in the stitches. Then, the large-diameter particles are caught by the filter of the smaller-diameter stitch, whereby the stitch is partially closed by the maximum-diameter particles, and then the smaller-diameter particles become the maximum-diameter particles. The gap formed between the particles and the filter stitch is partially closed, and thus the stitch filter advances the clogging by the particles having a small diameter one after another, and finally, the smallest particles having a size of, for example, 3 to 5 microns are removed. After that, the clogging occurs, and the rice cannot pass through the stitch filter due to the water permeability or the capillary action of the rice particles, but the water cannot pass through the filter. Thereby, a high filtering action can be exhibited.

[0009] The starch particles contained in the rice juice drainage are slightly heavier than the water, and have the property of sinking spontaneously if the rice juice drainage is kept stationary for a long time.
For this reason, larger particles are engaged with the mesh filter having a large mesh to close a part of the mesh, so that the area of the opening of the mesh is reduced, and the mesh having the small opening area is further closed. It is thought that the smaller particles close the mesh and the sharpening drainage is not filtered,
In reality, filtered water is drained regularly after a certain period of time. This is because during the filtration, the flow pressure of the rice sharpening drainage and the small particles once clogged the mesh, but settled down due to its own weight, and only water was drained or clogged from the small mesh opened. It is considered that the capillary action formed between the large and small particles causes only the water in the rice sharpener drainage to be filtered and drained.

Further, in the method for filtering rice juice drainage according to the second aspect of the present invention, the rice juice drainage is circulated through a circulation path for a predetermined time with a stitch filter interposed therebetween, whereby the rice stitch filter is clogged. The state is increased, and when the rice sharpener drainage is filtered into the required clear water by the stitch filter with the increased clogging, the rice sharpener drainage is switched from the circulation path to the drainage path, and A configuration is employed in which rice sharpening drainage is filtered and drained by a stitch filter with increased clogging.

According to the present invention, the stitch filter is positively clogged, whereby only the moisture is drained from the fine mesh, or formed by large and small particles closing the mesh. Due to the capillary phenomenon, only the water in the rice sharpening drainage is filtered and drained, whereby the filtration accuracy of the stitch filter is increased, and when the clarity reaches a predetermined clarity, the stitch filter has a higher filtration accuracy. Since the sharpening wastewater is filtered, it takes a long time to filter, but it can be filtered into highly clear water.

[0012] In a third aspect of the present invention, the method for filtering rice sharpener drainage employs the structure according to the first or second aspect, wherein the stitch filter is formed of a knitted cloth.

According to the present invention, the particles in the rice sharpening drainage uniformly mesh with the regular stitches of the knitted fabric to cause clogging, and the uneven surface for forming the stitches causes capillary action between the particles. Will effectively exhibit the effect of increasing the That is, the knitted fabric is rich in the uneven surface as compared with a plain-woven satin cloth or the like, and when the uneven surface is closed by the particles, the boundary portion of the unevenness, that is, the corner portion of the unevenness is closed by the particles. It is believed that very small openings are maintained, which promotes capillary action.

[0014] A method for filtering rice sharpening wastewater according to a fourth aspect of the present invention employs the structure according to the second aspect, wherein the knitted fabric is made of a knitted fabric.

According to the present invention, together with the above-mentioned effects, the filter cloth can be formed with a knitted cloth, which is the most uneven of knitted cloth, and is inexpensive. be able to.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a filtration apparatus for carrying out a filtration method of the present invention.
And a pump 2 for pumping up the rice juice drainage put into the tank upward. An upper tank 3 is provided on the upper side, and a pumping pipe 4 extending from the charging tank 1 is connected to the upper tank 3. The upper tank 3 is connected to a distribution pipe 7 provided in a filter box 6 by a drop pipe 5 extending from the tank. In addition, a flow rate adjusting cock 8 is appropriately provided on the falling pipe 5.

As shown in FIGS. 1 and 2, the distribution pipe 7 connected to the falling pipe 5 is provided with a large number of branch pipes 9 extending along the longitudinal direction thereof. The solenoid valve 10 is installed.

Then, as shown in FIG.
Is connected to a bag-shaped stitch filter 11.
The stitch filter 11 is, as shown in FIG. 1 or FIG.
The W-shaped bag body filter 11 is formed in a substantially W-shaped bag shape extending vertically and the W-shaped bag body filter 11 is held in a vertically elongated bag shape by a wire mesh type filter support spacer 12 along the outer peripheral surface. .

As shown in FIG. 4, the filter support spacer 12 is formed in a vertically elongated slender U-shape with a wire.
And vertical wire 12a that while the upper end portion 12a ₁ is to be slightly shorter, and a horizontal member 12b crossing each longitudinal wire made of assembled wire mesh form, as shown in FIG. 3, the pair filter Support spacers 12,12
Are arranged so that the short wires 12a1 at the upper end face _{each other, and} are detachably mounted in the filter box 6. The mesh filter 11 is substantially W-shaped in the pair of filter support spacers 12, 12. The upper end of each bag-shaped filter 11 is detachably locked to a needle or a hook 12c provided at the upper end of the filter support spacer 12.

As shown in FIG. 3, a pair of electrodes 13a and 13b are disposed near the upper end of the bag-like filter 11 by a suitable support member 14, and one of the electrodes 13a and 13b is connected to one of the electrodes 13a and 13b. The other electrode 13b extends shortly into the bag-shaped filter 11, and the other electrode 13b is short.
The tip of the electrode 13b is located at a position near the upper edge of the first electrode 13b. The pair of electrodes 13a and 13b are connected to the electromagnetic valve 10 and fill the bag-shaped filter 11 with the drainage to the upper end of the bag-shaped filter 11 by utilizing the conductivity of the rice sharpening drainage. Then, both electrodes 13a,
13b, both electrodes 13a, 13b
The solenoid valve 10 is turned on or off by energizing the valve to close the opening / closing section 10a, so that the drainage of rice sharpening juice is not sent into the bag-like filter 11, whereas the drainage of rice sharpening juice is supplied to the shorter one of the two electrodes 13a, 13b. When the pressure decreases below the electrode 13b, the electromagnetic valve 10 is opened to replenish the rice sharpener drainage into the filter 11.

As shown in FIG. 1, the filter box 6
A switching cock 15 is attached to the bottom of the tank, and a circulation pipe 16 and a discharge pipe 17 are connected to each other through the switching cock 15. The circulation pipe 16 is connected to the charging tank 1, and the discharge pipe 17 is connected to a public sewer or a secondary pipe. It is connected to a processing device 18.

In order to use the filtration device, rice drainage drained from a rice washing machine or the like is charged into an input tank 1 and the input rice drainage is passed through a pipe 4 by a pump 2 through an upper tank. Pumped to 3. When a certain amount is accumulated in the upper tank 3, the supply of the rice sharpening drainage to the charging tank 1 is temporarily stopped. The switching cock 15 at the bottom of the filter box 6 is switched so as to communicate with the circulation pipe 16.

In this state, the rice drainage in the upper tank 3 is sent from the falling pipe 5 through the distribution pipe 7 and the branch pipe 9 into the bag-shaped stitch filter 11. The rice sharpener drainage sent into the filter 11 passes through the mesh of the filter 11 and returns to the charging tank 1 via the switching cock 15 and the circulation pipe 16. The rice sharpener drainage returned to the input tank 1 is pumped by the pump 2 to the upper tank 3 and again the stitch filter 1.
1 and then circulated to the charging tank 1.
As the rice juice drainage passes through the above-described circulation path, as shown in FIG. 5A, the particles S1 having a large particle size initially mixed into the rice sharpener drainage are stitches 11a of the stitch filter 11.
Clogged up. As time passes, particles S2 having a medium size and particles S3 having a small particle size as shown in FIGS.
Are successively caught by the stitches 11a of the filter 11 and the clogging proceeds, and finally the starch particles S1 to S3 cover the entire inner surface of the filter 11 and cause clogging to such an extent that the particles are not allowed to pass. After that, only the moisture passes through the filter 11 due to the capillary action in these particles, and is circulated as clear water.

As described above, by circulating the rice sharpening wastewater in the circulation path with time, the switching cock 15 is visually inspected or when the wastewater inspection shows that the predetermined clarity has been reached. It is switched so as to communicate with the drain pipe 17 side, and thereafter, the rice sharpening drainage is charged into the input tank 1, the drainage is pumped up to the upper tank 3 by the pump 2, and filtered by the stitch filter 11. Continuous operation is performed while maintaining the liquid level in the filter 11 constant by the electrodes 13a and 13b facing the stitch filter 11 serving as a water level detecting means.

That is, FIG. 6 shows the amount of filtered water per 0.25 m ² and the filtration time of the stitch filter 11 made of a knitted cloth until rice sharpener drainage is drained as predetermined clear water. This is the initial stage of circulation when the filtered water volume of the stitch filter 11 is 4 liters, and shows a point in time when the particles S1 having a large particle size are clogged in the stitch filter 11. "b" indicates a point in time when the amount of filtered water is 3 liters and the particles S2 having a medium particle diameter are clogged. “c” indicates the point in time when the amount of filtered water is 3 to 2 liters and the small-sized particles S3 are clogged. At the time point d, the large, medium and small diameter particles S1 to S3 are completely clogged in the stitch filter 11, and the BOD value of water passing through the filter 11 can be drained to the public sewer.
It shows a state where it has dropped to 0 ppm.

Then, when the state of d is reached, the switching cock 15 is switched to communicate with the drain pipe 17 side as described above, and thereafter, the rice sharpening drainage is charged into the charging tank 1 and the mesh filter is provided. The filtered waste water is continuously discharged to the public sewer or the secondary treatment device 18 while keeping the liquid level in the liquid 11 constant.

According to this filtration method, space saving, energy saving and cost saving can be suppressed, and the total BO
D is 5000 to 22000 ppm of rice juice drainage, and the treated amount per day is 3 tons.
It can be less than 00 ppm.

It is preferable that a washing device for washing the upper tank 3 be attached after the work of the day is completed.

After the work is completed, the cover 6a of the filter box 6 shown in FIG. 1 is removed, and the mesh filter 11 together with the filter support spacer 12 or only the stitch filter 11 is removed by the hook 12c of the support spacer 12 to remove the filter box. 6 needs to be picked out and replaced with a new filter 11. For example, when 2,500-3000 liters of wastewater is discharged, 30 kg of a clay-like filtrate containing about 30% of water is generated by treating the wastewater.

The stitch filter 11 needs to be replaced every day at the end of each day's work. For this purpose, the stitch filter 11 must be of a low-cost disposable structure and have good filtering accuracy due to clogging. Moreover, the filter 11
Must withstand the weight of about 1.5 kg deposited on the Paper cannot meet the above conditions. A knitted fabric can be mentioned as one that meets the above purpose.

The filtration phenomenon of the knitted cloth by the filter 11 will be described with reference to FIG. 7. The starch particles contained in the rice sharpener drainage are slightly heavier than the water content. It has the property of sinking. For this reason, the mesh filter 11 having a large mesh and 11 in FIG. 7 show one thread of the filter. The mesh 11a formed by the single thread 11 is engaged with a mesh S1 larger than the mesh 11a. Part of the mesh 11a is closed, the area of the opening of the mesh 11a is reduced, and the particles S2 to S3 smaller in diameter are closed so as to also mesh the mesh 11a having the small opening area. It is considered that the juice drainage is not filtered, but in reality, the filtrate is drained regularly after a certain period of time. This is due to the flow pressure of the rice sharpener drainage during the filtration, and once the small-sized particles S2 to S3 block the mesh 11a, but sink downward due to its own weight, whereby only water is drained from the small mesh opened, Alternatively, it is considered that only the water in the rice sharpener drainage is filtered and drained due to the capillary phenomenon formed between the blocked large and small particles.

At this time, the particles in the rice sharpening drainage are uniformly entangled in the regular stitches of the knitted fabric to cause clogging, and the uneven surface for forming the stitches is formed as shown in FIG. The effect of effectively enhancing the capillary action between particles is exhibited. That is, knitted fabric, rich in uneven surface compared to satin cloth of plain weave, the boundary portion of the uneven when the uneven surface 11a is blocked by the particles, i.e. the unevenness of the corner portions in 11a ₁ particles S1~ It is considered that an extremely small opening is maintained without being blocked by S3, which promotes the capillary phenomenon.

Among them, as a result of the experiment, it was found that a filter made of knitted fabric was the best. In order to form a bag-shaped filter using the knitted fabric, as shown in FIGS.
9 is cut to an appropriate length and its cut end 19a is sewn,
The central portion 19b is cut open on one surface side and is folded in two around the opening portion 19b. As shown in FIG. 9, the branch pipe 9 is used so that the distal end of the branch pipe 9 faces the opening portion 19b. According to a trial calculation, a total cost of about 2,000 yen is required for a whole rice filter when washing with 2 tons of rice.

There is also a method in which the filter 11 picked up from the filter box 6 after the work is completed and the contents deposited thereon are incinerated as garbage.
The contents can be removed and reused.

Further, as shown in FIG. 10, a hot air drying device 20 may be provided inside the filter box 6 to dry the contents of the filter after the operation is completed. According to this method, the contents can be taken out from the filter 11 in a fluffy state by drying the contents, and can be directly processed as garbage, but can also be used as animal feed. is there. An exhaust pipe 21 is connected to the cover 6a, and is provided with an exhaust fan 22.

[0036]

According to the method for filtering rice juice drainage according to the first aspect of the present invention, rice juice drainage is mostly SS component (suspended matter, mainly starch particles) and dissolved BOD component is not. Focusing on the fact that rice starch particles of various sizes are suspended and mixed in water, rice starch fine particles with a particle size of several microns to several hundreds of microns are used. It is characterized by performing adsorption filtration with a filter. That is, the rice sharpener drainage is passed through a filter and the particles having the largest diameter are caught in the stitches. As the largest diameter particles are caught by the filter of the smaller diameter stitch, the stitch is partially closed by the largest diameter particles, and then the smaller diameter particles are filtered with the largest diameter particles. The gaps between the stitches are partially closed, and thus the stitch filters are progressively clogged by particles having a small diameter one after another, and finally clogging occurs in which the smallest size particles do not pass. Utilizing water permeability or capillary action of rice particles, particles cannot pass through the stitch filter, but water can pass through the filter, thereby exhibiting a high filtering action. .

According to this filtering method, it is only necessary to install a large number of mesh filters, tanks, and an automatic opening / closing mechanism, so that there is an advantage that the equipment cost is very small.

Further, according to the method for filtering rice sharpener drainage according to the second aspect of the present invention, the stitch filter is positively clogged, thereby increasing the filtration accuracy of the stitch filter to a predetermined clarity. Since the rice sharpener drainage is filtered by a stitch filter with improved filtration accuracy, it takes a long time to filter, but it can be surely filtered to a desired high degree of clear water.

According to the method for filtering rice juice drainage according to the third aspect of the present invention, the particles in the rice juice drainage uniformly mesh with the regular stitches of the knitted fabric, causing clogging and forming the stitches. The uneven surface for performing the function effectively enhances the capillary phenomenon between particles.

Further, according to the method for filtering rice sharpener drainage according to the fourth aspect of the present invention, the filter cloth can be formed with the cheapest knitted cloth among the knitted cloths together with the above operation, so that the filter cloth can be formed at a lower cost. can do.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a filtration device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the main part.

FIG. 3 is an enlarged sectional view of the main part.

FIG. 4 is a perspective view of the main part.

FIGS. 5a to 5c show the state of particles clogged with respect to a mesh filter over time.

FIG. 6 is a graph showing a change in the amount of filtered water.

FIG. 7 is a diagram illustrating a filtration phenomenon according to the present invention.

FIGS. 8A to 8D are diagrams illustrating a process of manufacturing a filter cloth according to an embodiment of the present invention.

FIG. 9 is a diagram showing an attached state of the filter cloth.

FIG. 10 is an explanatory view of a main part of a filtration device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input tank 2 Pumping pump 3 Upper tank 4 Pumping pipe 5 Dropping pipe 6 Filter box 7 Distribution pipe 8 Flow control cock 9 Branch pipe 10 Solenoid valve 11 Mesh filter 11a Mesh 12 Filter support spacer 13a Electrode 13b Electrode 14 Supporting cock 15 Switch cock 16 Circulation pipe 17 Drainage pipe 18 Public sewer

Claims (4)

[Claims] 1. A method for filtering rice sharpening wastewater containing mixed particles of 3 μm to 1000 μm in size, wherein the stitches of the mixed particles contained in the wastewater are such that the largest diameter particles do not pass through. A method for filtering rice sharpener drainage, wherein the drainage is filtered using a large stitch filter. 2. The rice sharpener drainage is circulated through a circulation path for a predetermined time with a stitch filter interposed therebetween.
When the clogged state is increased in the stitch filter, and the rice sharpening drainage is filtered to the required clear water by the stitched filter with the increased clogging, the rice sharpening drainage is removed from the circulation path. A method for filtering rice sharpener drainage by switching to a drainage path and filtering and draining the rice sharpener drainage by the stitch filter having the increased clogging. 3. The method according to claim 1, wherein the stitch filter is made of a knitted fabric. 4. The method according to claim 3, wherein the knitted fabric is a knitted fabric.