JPH0691141A - Recovering method of waste water from rice washing, and device therefor - Google Patents

Abstract

PURPOSE:To provide a method and a device to regenerate water used to wash rice so that the supply flow amt. of washing water for rice to a rice washing device can be maintained, pollution of washing water for rice is suppressed, rice can be washed in high quality, the amt. of water consumed can be decreased by circulation of water, regeneration can be performed in a small area at low cost, and the device is made inexpensive. CONSTITUTION:Waste water 12 of washing water for rice from a rice washing device is filtered with a filtering device 14 to obtain a liquid filtrate 16. The liquid filtrate 16 is filtered with ultrafilter membranes 17, 20 to obtain permeated water 19, 22. Pure water 27 is added to the permeated water 19, 22 to control BOD of the liquid not to exceed the specified value, and the water is supplied to the rice washing device as washing water 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for regenerating waste water discharged when washing polished rice.

[0002]

2. Description of the Related Art An apparatus for producing so-called "non-washed rice" that can be cooked without polishing has already been proposed by the present inventor (Japanese Patent Application No. 4-6363). This is to wash polished rice with water,
Immediately after that, remove the water adhering to the surface of the polished rice (dry)
By doing so, it is intended to obtain non-washed rice excellent in taste and storability.

Normally, about 3% by weight of polished rice is used for washing rice.
Rice bran, starch, proteins, fats and oils are removed by being dissolved or suspended in washing water as the substances to be removed. Since the non-washed rice manufacturing apparatus normally uses 1 to 3 times the weight of polished rice to be treated for washing water, the waste water for washing rice generated by this is BO.
When it becomes a high concentration of 10,000 to 30,000 PPM in D, and when treating a large amount of polished rice such as 1 t / hour or more, it is necessary to purify it by a wastewater treatment facility before discharging the wastewater into a river or a sewer. .
Most of the wastewater treatment facilities for washing rice installed for this purpose are biological treatment.

[0004]

However, since the above-mentioned system for washing and treating waste water of rice requires a large-area settling tank, biological treatment tank, sludge separation tank, etc., it is necessary to be located in an urban area where the population is concentrated. There is a problem in that it is not possible to secure a place for installing the rice in the rice mill, and thus it is not possible to install a non-washed rice manufacturing apparatus in the rice mill. Further, the conventional rice-washing wastewater treatment facility uses a large amount of water, and there is a problem that the equipment cost and operating cost thereof are high, and further, the water treated by the conventional rice-washing wastewater treatment facility is purified. However, it was not suitable to be used for washing rice again, and therefore it was very unlikely that the reuse of treated water would reduce the water consumption.

[0005] The idea of reusing the waste water for washing rice for washing rice in order to reduce the consumption of water is, for example, Japanese Patent Publication No.
-11968 and Japanese Patent Laid-Open No. 63-148940, these have existed in the past, but these can be reused as they are without filtering rice washing wastewater, or even if filtered, the turbidity of rice washing wastewater can be reduced at best. However, the BOD of the washing water becomes high, which makes the cooked rice have a bad odor when cooked as rice for cooking, even if it is processed into rice crackers. Was unavoidable.

In order to solve the above problems, the present invention secures a flow rate of the washing water to the washing machine and suppresses water contamination of the washing water to enable high quality washing, It is an object of the present invention to provide a method and apparatus for reclaiming rice-washing wastewater, which can reduce the amount of water consumption by recycling the water, can be processed in a small area, and have a low processing cost.

[0007]

In order to achieve the above object, the method for reclaiming washed rice effluent according to the present invention comprises the steps of separating the washed rice effluent from the rice washing device into a filter residue and a filtrate,
The filtrate is separated into a concentrated liquid and membrane permeated water by an ultrafiltration membrane, and a predetermined amount of fresh water is added to the membrane permeated water to adjust the BOD so as not to exceed a predetermined value. It is characterized in that it is supplied to the rice washing device as water.

[0008] Further, when the rice washing apparatus is out of operation, the washing water is
Cool to ~ 5 ° C and store, and during operation, heat this to around 25 ° C and supply it to the rice washing device, or evaporate the filter cake from the filter and the concentrated liquid from the ultrafiltration membrane to obtain a dry solid. Or to obtain the drainage water by condensing the steam generated when the filter cake from the filter and the concentrated liquid from the ultrafiltration membrane are evaporated.

Further, the apparatus for reclaiming washed rice sewage according to the present invention comprises a filter for separating the effluent from the washed rice from the rice rinsing apparatus into a filter residue and a filtrate, and a filtrate from the filter into a concentrate and a membrane permeate. A plurality of ultrafiltration membranes separated into, a heating drier for evaporating the filter cake from the filter and the concentrated liquid from the ultrafiltration membrane to obtain a dry solid, and the ultrafiltration membrane It is characterized in that a circulation circuit of the washing water for supplying the membrane-permeated water from (3) to the washing machine as washing water is formed again.

[0010]

In the present invention, first, the rice washing wastewater containing the substances to be polished rice removed from the rice washing apparatus is filtered by a filter to remove the large amount of SS substances from the substances to be polished rice floating in the rice washing drainage. It is separated into a filter cake containing a portion and a filtrate from which most of the SS substance is removed. Then, the filtrate is separated by an ultrafiltration membrane into a concentrated liquid containing a large amount of a polymer substance and a membrane-permeated water from which a polymer substance having a certain molecular weight or more is removed. A predetermined amount of fresh water is added to the membrane-permeated water, the BOD of which is adjusted, and then the water is again supplied to the rice washing apparatus as washing water. The filter residue from the filter and the concentrated liquid from the ultrafiltration membrane have a very high solid content and can be easily treated by various methods.

[0011]

Embodiments of the present invention will be described with reference to the drawings. A rice washing apparatus combined with the rice washing wastewater regeneration treatment apparatus of the present invention is, for example, a non-washed rice manufacturing apparatus as shown in FIG. This has almost the same structure as that proposed in Japanese Patent Application No. 4-6363, and reference numeral 1 generally indicates the device. The non-washed rice manufacturing apparatus 1 includes a raw material tank 2 and
A screw feeder 3 for quantitatively discharging the polished rice in the raw material tank 2, a primary washing unit 4 and a secondary washing unit 5 for washing the polished rice discharged from the raw material tank 2, and a drying unit for drying the polished rice after washing. 6 and 6. 7, 8 and 9 are water supply pipes for supplying washing water, and 10 and 1
Reference numeral 1 is a drainage pipe for discharging wastewater from washing rice.

The operation of the non-washed rice producing apparatus 1 is as follows. First, the milled rice stored in the raw material tank 2 is taken out at a constant flow rate by the screw feeder 3 and is introduced into the primary rice washing section 4, and the washing water from the water supply pipe 7 is added, and the rice is stirred and rubbed into particles. The product to be removed, such as bran, is removed from the polished rice, the washed rice drainage containing the removed product is discharged from the drain pipe 10, and the washed polished rice is fed to the secondary washing unit 5. In the secondary washing unit 5, first, the material to be removed attached to the polished rice is diluted with the washing water from the water supply pipe 8, and then the polished rice is poured into the washing water from the water supply pipe 9 while being centrifugally dehydrated. The material to be removed is rinsed and washed, and the washing water containing the material to be removed is drained 11
The milled rice that has been discharged from and dehydrated is put into the drying unit 6. In the drying unit 6, the water slightly remaining on the surface of the polished rice is dried by wind and discharged as unwashed rice.

Next, referring to FIG. 1, a rice-washed wastewater regeneration treatment device according to the present invention, which is combined with the above-mentioned unwashed rice manufacturing device 1, will be described. 13 is a drainage pipe 10 of the non-washed rice manufacturing apparatus 1
Reference numeral 14 denotes a drainage tank for storing the rice-washing wastewater 12 discharged from 11 and 11, and 14 denotes a filter for separating the rice-washing wastewater from the drainage tank 13 into a filter residue 15 and a filtrate 16. The filter 14 is required to be able to collect most of the SS substances in the rice sewage drainage and take it out as a filter residue 15,
Moreover, it is desirable that the water content of the filter cake 15 can be about 70% or less for the drying step described later, and for example, a filter press or the like is suitable.

Reference numeral 17 is a first ultrafiltration membrane which separates the filtrate 16 from which most of the SS substances have been removed by the filter 14 into a concentrate 18 and a membrane permeate 19 and has a molecular weight cutoff of 100.
About 00 is suitable. Reference numeral 20 is a second ultrafiltration membrane that further concentrates the concentrated liquid 18 by the first ultrafiltration membrane 17 and separates it into a concentrated liquid 21 and a membrane permeated water 22. This fractionated molecular weight is also the first ultrafiltration membrane. Similar to membrane 17. 23 is the membrane permeated water 1 from the first ultrafiltration membrane 17 and the second ultrafiltration membrane 20.
It is a washing water tank for storing 9 and 22. The water in the washing water tank 23 is washed by a pump (not shown).
4 is supplied to the water supply pipes 7, 8 and 9 of the non-washed rice manufacturing apparatus 1.

Reference numeral 25 is a cooler for lowering the temperature of the water in the washing water tank 23, and 26 is the washing water 2 stored at a low temperature.
It is a warmer that heats the temperature of 4 before use. Also, 27
Is fresh water from the tap water added to the washing water tank 23, 28 is overflow drainage water 28 discharged from the washing water tank 23, and 29 is dilution water (fresh water) added to the overflow drainage water 28.

Reference numeral 30 is a dryer for drying the filter residue 15 from the filter 14 and the concentrated liquid 21 from the second ultrafiltration membrane 20 to separate them into steam 31 and dry solids 32. Although the method of the dryer 30 is arbitrary, a heating dryer is generally suitable.

Next, the operation of the above embodiment will be described. Prior to the start of operation, fresh water 27 is poured into the washing water tank 23 up to a predetermined amount. Then, the water in the rice washing water tank 23 is supplied as the washing water 24 to the water supply pipes 7, 8 and 9 of the non-washed rice manufacturing apparatus 1 to start the operation of the non-washed rice manufacturing apparatus 1. The supply flow rate of the washing water 24 is preferably about 1 to 3 times (weight ratio) of the flow rate of the milled rice to be treated, and if it is less than this, stirring force, centrifugal force and wind force added to the milled rice should be strong. The rice cannot be washed sufficiently, and the quality and taste of rice are likely to deteriorate.

After the washing water 24 supplied to the water supply pipes 7, 8 and 9 is used for washing rice in the non-washed rice producing apparatus 1,
The material to be removed of the polished rice is discharged from the drain pipes 10 and 11, and is stored in the drain tank 13 as the washed rice drainage 12. BOD at this point is 10,000 to 30,000 PP
It is about M. The washed rice drainage 12 is then passed through a filter 14, and among the substances to be removed from the polished rice that are floating in the washed rice drainage 12, debris of rice grains, large starch particles, fibrin contained in the bran layer, etc. Most of SS substances are filter residue 15
And is supplied to the first ultrafiltration membrane 17 as the filtrate 16.

The molecular weight cutoff of the first ultrafiltration membrane 17 is 100.
Since it is about 00, the filtrate 16 is separated into a concentrated liquid 18 containing substances having a molecular weight of 10,000 or more, for example, fine starch particles, proteins, fats and oils, and the membrane permeated water 19 from which these substances have been removed. Subsequently, the concentrated liquid 18 is supplied to the second ultrafiltration membrane 20 and separated into a concentrated liquid 21 in which a substance having a molecular weight of 10,000 or more is further concentrated and a membrane permeated water 22.

The membrane-permeated water 19 and the membrane-permeated water 22 are combined and put into and stored in the washing water tank 23. At this point, the SS substance is zero and the BOD is also a very low value. Most of the bacteria have also been removed. And
The water in the rice washing water tank 23 is supplied again to the water supply pipes 7, 8 and 9 of the non-washed rice manufacturing apparatus 1 as the washing water 24. In the present embodiment, as described above, the non-washed rice producing apparatus 1 → drainage tank 13 → filter 14 → first ultrafiltration membrane 17 → (second ultrafiltration membrane 20) → rice washing water tank 23 → non-washed rice production apparatus 1 That is, a circulation circuit for washing water is formed.

Further, the filter residue 15 from the filter 14 and the concentrate 21 from the second ultrafiltration membrane 20 are mixed and dried.
0, where it is dried and separated into steam 31 and dry solids 32, which is released outdoors. The component of the dry solid 32 has a high nutritional value, mainly starch, and can be used for feed or the like.

The circulating washing water is lost as steam 31 and is evaporated in the drying section 6 of the non-washed rice manufacturing apparatus 1 or absorbed by the polished rice while passing through all the steps of the non-washed rice manufacturing apparatus 1. Then, it will decrease by a fixed amount. In order to prevent this, it seems that it is necessary to operate while supplying the same amount of water as the decreasing washing water, but then the substances with a molecular weight of 10,000 or less contained in the washing water gradually increase and the BOD rises. This is about 9
It has been found that if the amount exceeds 00 PPM, there is a high possibility that bran odor will remain on washed rice (non-washed rice).

From the above, in order to suppress the BOD of the washing water to 900 PPM or less, the fresh water 27 having a flow rate slightly larger than the weight of the washing water lost per unit time is supplied to the washing water tank 23. Further, as a result, the washing water exceeding the predetermined amount is discharged as overflow drainage 28. Diluted water 29 is added to the overflow drainage 28, and the BOD of the diluted drainage 29 is discharged to a value below the drainage standard value for discharge to a river or sewer before being discharged.

Actually, in order to release the BOD when it is discharged into a river or a sewer to 50 PPM or less, which is a general drainage standard value, the amount of fresh water 27 to be added is 15 to 20% by weight of polished rice. As a result, the BOD of washing water
Was balanced at 150 to 200 PPM, so the overflow drainage 28 to be discharged was diluted with 2 to 3 times its weight of dilution water 29.
I should have added. At this time, the total drainage amount of overflow drainage 28 and dilution water 29 is 3 of polished rice.
The amount of water consumed after the start of operation is 0 to 40% by weight, that is, the total flow rate of the fresh water 27 and the diluting water 29 is 3% of that of the polished rice.
It was 5 to 48% by weight. Conventionally, the non-washed rice manufacturing apparatus 1 alone consumes 1 to 3 times as much water as polished rice, and if a biological treatment system wastewater treatment facility is attached to this, it will consume several to several dozen times as much water. It can be said that the water-saving effect of the present invention is extremely large as compared with the case where the BOD could not be reduced to the drainage standard value or less without consumption.

In addition, since the present invention has a circulation circuit for washing water, it consumes a small amount of water, but is 1 to 3 times the weight of the flow rate of milled rice to be treated (if necessary, more than that). (Possible) rice washing water can be supplied, and the abundant amount of water makes it possible to wash rice without deteriorating the quality and taste of rice.

In the above embodiment, the filter residue 15 and the concentrated liquid 21 were dried by the dryer 30, but the dryer 30 is not always necessary. This is because the filter cake 15 and the concentrated liquid 21 have a very high solid content and a high nutritional value, and may be used as they are as feed for livestock such as pigs or as fertilizer for agricultural crops. Also,
In the above embodiment, an example using two ultrafiltration membranes is shown.
The number may be three or more, and details such as a place where the fresh water 27 is added are not limited to those in the above embodiment.

In the above embodiment, the non-washed rice producing apparatus 1 has been described as an example of the rice washing apparatus, but the combination with the present invention is not limited to the non-washed rice producing apparatus. Needless to say, any rice washing device may be used as long as it has a step of washing rice with water, and rice washing drainage from a conventional rice washing device used in a rice cooking plant or the like can be treated by the present invention. Absent.

In the conventional wastewater treatment equipment, the equipment cost and the installation area are major obstacles to the introduction of the equipment. However, in the present invention, the number of them is extremely small, so that it is impossible to have the wastewater treatment equipment in the past. It will also be possible for urban contractors and small and medium-sized contractors to install the equipment. In addition, in the conventional wastewater treatment facility, in addition to a large amount of water charge and sewerage charge, electricity cost, bacterial cost for biological treatment, sludge treatment cost, etc. are required, but the operating cost is high, but the operating cost in the present invention is Energy charges (electricity charges, gas charges or kerosene charges when using a heating dryer) and a small amount of water and sewerage charges are required, and the total operating cost is only about 1/2 or less of the conventional cost. Further, in the present invention, since no chemical such as a flocculant is used, it is safe and the operation and maintenance are easy because of its simple structure.

After the operation for one day, all the washing water existing in the apparatus may be discharged, but since it must be diluted before it is discharged, the water and sewer charges will be high. Become. Therefore, as shown in FIG.
And the warmer 26 is provided, and the cooler 2 is provided after the end of one day
When 5 is operated for an appropriate time, the temperature of the washing water in the washing water tank 23 is lowered to 0 to 5 ° C., the rice washing water is stored so as not to rot, and the next non-washing rice producing apparatus 1 is operated again. , Activate the warmer 26 to increase the temperature of the washing water 24 to 25
It may be supplied to the non-washed rice producing apparatus 1 while being raised to around 0 ° C. The heating by the warmer 26 is performed to improve the efficiency of rice washing and to improve the water permeability of the first ultrafiltration membrane 17 and the second ultrafiltration membrane 20. The water temperature need not be exactly 25 ° C. Of course, the warmer 26 may be stopped after the temperature of the washing water in the washing water tank 23 has risen sufficiently.

2 and 3 show an embodiment of the dryer 30, and the inside of the box-shaped main body frame 33 is divided into upper and lower parts by a partition plate 34 except for a part thereof. Below the partition plate 34, a drum 36 is provided which is driven to rotate by a motor 35. 37 is a conduit for introducing the filter residue 15 and the concentrated liquid 21 into the drum 36, and 38 is a nozzle hole formed in the conduit 37. Reference numeral 39 is a gas burner, 40 is a screw scraper inserted from the outside of the main body frame 33 so as to face the inner wall surface of the upper portion of the drum 36, and 41 is a motor for rotationally driving the screw scraper 40. 42 is a trough provided so as to surround the lower side of the screw scraper 40, and 43 is a discharge port opened on the bottom surface of the trough 42 on the motor 41 side. Reference numeral 44 denotes a heat pump. The heat pump 44 is provided above the compressor 45 and the partition plate 34 in the main body frame 33, and has a cooling fin 46 and a radiating fin having a passage for a refrigerant such as CFC therein. And 47. Reference numeral 48 is a water pan provided below the cooling fins 46, and 49 is a drain pipe connected to the water pan 48. Reference numeral 50 is an electric fan provided facing one end of the drum 36.

The drum 36 is rotated in the direction of arrow A by the motor 35, and its side wall is covered with a gas burner 39.
Is heated by. When the mixture of the filter residue 15 and the concentrated liquid 21 is sprayed from the nozzle hole 38 on the inner wall surface of the drum 36, the moisture of the mixture is evaporated by heat and the solid content is spread on the inner wall surface of the drum 36. . When the screw scraper 40 reaches a certain position by the rotation of the drum 36, the rotating screw scraper 4
It is scraped off by 0 and falls on the trough 42, is further transferred to the motor 41 side by the screw scraper 40, and is discharged from the discharge port 43.

Further, the electric fan 50 causes an air flow as indicated by an arrow B inside the main body frame 33,
The air containing the steam exits from the other end of the drum 36, goes around to the upper side of the partition plate 34, reaches the cooling fin 46, and the heat of vaporization of the refrigerant is removed inside the cooling fin 46. The water is condensed and condensed on the surface, flows down, drops on the water receiving tray 48, and is discharged as drain water from the drain pipe 49. The air thus dried by removing the water vapor reaches the radiating fins 47. Inside this, the refrigerant compressed by the compressor 45 condenses, so that the heat generated at that time heats the air, further lowering the relative humidity thereof, and the electric fan 50 causes the electric fan 50 to re-emit the inside of the drum 36 again. Sent to.

When a drier for drying the mixture of the filter cake 15 and the concentrated liquid 21 is provided, the water vapor generated from the drier has a slight odor, so that it is a problem to release it outdoors in a dense residential area. However, in this case, it is possible to prevent the odor from being emitted to the outside by using the dryer 30 as described above. The drain water has a low BOD and can be discharged as it is to a river or a sewer.

[0034]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, when it is used in combination with a rice washing device, it is possible to drastically reduce the consumption of water and secure a large amount of water for washing rice. Since it suppresses the pollution of the washing water, it enables high-quality rice washing, and does not require a large area for wastewater treatment,
The facility and operation costs of wastewater treatment can be greatly reduced compared to the conventional one, and it has an extremely useful effect.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of a rice washing wastewater recycling treatment apparatus according to the present invention.

FIG. 2 is a diagram illustrating an example of a dryer.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a cross-sectional view showing a non-washed rice producing apparatus.

[Explanation of symbols]

 1 Non-washed rice manufacturing device as an example of a rice washing device 12 Washed rice drainage 14 Filter 15 Filter residue 16 Filtered liquid 17 First ultrafiltration membrane 18 Concentrated liquid 19 Membrane permeated water 20 Second ultrafiltered membrane 21 Concentrated liquid 22 Membrane permeation Water 24 Washing water 27 Clean water 30 Dryer 49 Drain pipe

Claims (5)

[Claims] 1. A rice washing drainage from a rice washing apparatus is separated into a filter residue and a filtrate by a filter, and then the filtrate is separated by an ultrafiltration membrane into a concentrate and a membrane-permeated water. A method for reclaiming rice waste water, which comprises supplying a predetermined amount of fresh water to water so that the BOD of the water does not exceed a predetermined value and supplying the water as rice washing water to a rice washing apparatus. 2. The washing water is 0 to 5 when the operation of the washing machine is stopped.
The method for reclaiming rice-washing waste water according to claim 1, wherein the method is stored at a temperature of ℃, stored, and heated during operation to about 25 ° C and supplied to a rice-washing device. 3. The method for reclaiming washed rice sewage according to claim 1, wherein the filter cake from the filter and the concentrated liquid from the ultrafiltration membrane are evaporated to obtain a dry solid. 4. The washing effluent regeneration treatment according to claim 3, wherein steam generated when the filter residue from the filter and the concentrated liquid from the ultrafiltration membrane are evaporated is taken out as drain water. Method. 5. A filter for separating the waste water from the rice washing device into a filter residue and a filtrate, and a plurality of ultrafiltration membranes for separating the filtrate from the filter into a concentrate and a membrane-permeated water. A heating drier for evaporating the filter cake from the filter and the concentrated liquid from the ultrafiltration membrane to obtain a dried solid, and the membrane permeated water from the ultrafiltration membrane is used as washing water again. A rice-washing wastewater reclamation treatment device characterized in that a circulation circuit for washing water to be supplied to the rice-washing device is formed.