JPH08267051A - Method for recovering bran component from waste water of rice washing and device for recovering bran component therefrom - Google Patents

Abstract

PURPOSE: To recover a bran-component which is reusable from waste water of rise washing and to efficiently purify the waste water of rice washing. CONSTITUTION: While flocs are formed by mixing a flocculating agent with the waste water of washing rice in a flocculating tank 1, the high-pressure water dissolved with air in a high concn. by pressurization in a fine air bubble forming device 2 is reduced in pressure and fine air bubbles are generated in a dissolving liquid to form fine air bubbles. These two liquids are mixed to adsorb the fine air bubbles in the flocs. The flocs are floated in a flotation vessel 3. Scum 30 formed by sepn. of solid from the liquid without modification is recovered. The release of the cleaned waste water is made possible.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention collects a waste liquid of rice washing work, which is generated in association with sake brewing and non-washed rice production, that is, a rice powder component called reusable rice bran drainage, and purifies the rice wash drainage. The present invention relates to a method for recovering bran content from waste water of washing rice and a bran content recovery apparatus used for the implementation.

[0002]

2. Description of the Related Art Conventionally, waste water for washing rice has been purified by a waste water treatment apparatus comprising an aeration tank 40 and a sedimentation tank 50 shown in FIG. 3, and discharged to a public sewer or the like. That is, the rice washing wastewater from the rice washing workshop is sent to the aeration tank 40 which holds the microorganism mixed culture as activated sludge, where the organic matter in the rice washing wastewater is due to the food chain reaction of the microorganisms in the activated sludge,
It is coagulated, adsorbed, oxidatively decomposed, reduced in weight, and modified into sludge that easily precipitates. Subsequently, the wastewater treated with microorganisms in the aeration tank 11 is sent to a settling tank 50, where sludge is precipitated and removed, and then discharged to a public sewer or the like as purified treated water. The sludge that has settled is continuously or regularly collected, dehydrated, and discarded.

[0003]

As described above, the above wastewater treatment device is intended only for purifying the wastewater for washing rice, and the originally usable bran in the wastewater for washing rice is recovered and reused. Didn't. Therefore, useful resources were wasted.

Further, since this wastewater treatment equipment utilizes biological reaction such as food chain of microorganisms, there is a problem that the purification treatment requires a long time and the treatment equipment becomes large and requires a vast installation space.

Furthermore, in order to maintain the apparatus, it is troublesome that the amount of organic matter necessary for the survival of the microorganisms has to be periodically replenished.

[0006] The present invention solves the above-mentioned problems of the prior art, recovers reusable bran content from rice rinsing wastewater, and efficiently recovers the rice rinsing wastewater from the rice rinsing wastewater and recovers the bran content. The purpose is to provide a device.

[0007]

In order to solve the above problems, the method for collecting bran fraction of the present invention comprises a step of mixing an aggregating agent with waste water of washing rice to produce an agglomerate, and a high concentration air by pressurization. The process of decompressing the solution to generate fine bubbles in the solution, mixing the washing water from which the agglomerate was generated with the solution in which the fine bubbles were generated, and floating the agglomerates for solid-liquid separation It is characterized by including a step and a step of collecting the floated aggregate. Further, the bran fraction recovery device of the present invention, a coagulation tank that mixes a flocculant in the rice rinsing wastewater to generate coagulates,
From the mixture of two liquids supplied from the fine bubble liquid generator that decompresses the high-concentration air dissolved liquid by pressurization to generate fine bubbles in the dissolved liquid, and the aggregation tank and the fine bubble liquid generator,
The present invention is characterized by comprising a flotation separation tank that floats aggregates to perform solid-liquid separation. Chitosan is preferable as the aggregating agent.

[0008]

[Function] When the solution containing fine bubbles is mixed with the rice washing water in which the aggregates are aggregated, the bubbles are adsorbed to the aggregates. Therefore, since buoyancy acts on the aggregate, the aggregate floats in the floating separation layer and solid-liquid separation is performed. That is, aggregates are collected in the surface layer portion of the mixed liquid in the floating separation layer. Therefore, the aggregates can be easily collected. Moreover,
According to this solid-liquid separation, there is no possibility that the bran fraction in the agglomerate is denatured due to a biological reaction. Therefore, the bran can be collected in a usable state. Therefore, it can be used as a raw material for organic fertilizers and biodegradable / biodegradable plastics. In addition, the wastewater that has been solid-liquid separated is automatically cleaned. Therefore, it will not cause environmental problems even if it is directly discharged to public sewers. When chitosan is used as the coagulant, chitosan is edible, so the collected bran is a raw material for biodegradable / biodegradable plastics such as tableware, feed, and Japanese sweets. It can be used for food materials such as. Furthermore, by utilizing the functional food properties of chitosan, it can also be used as a high value-added health food material.

[0009]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic front view showing an example of a bran fraction collecting apparatus used for carrying out the method of the present invention. This bran content recovery device includes a flocculation tank 1, a fine bubble liquid generation device 2 and a floating separation tank 3.
It has.

A stirring device 10 is arranged in the flocculation tank 1. To the bottom surface of the flocculation tank 1 is connected one end of a pipe 11 for feeding and washing rice drainage. The other end of the pipe 11 is the pipe 20 for mixing two liquids.
Connected in the middle of. One end of the pipe 20 is connected to the fine bubble liquid generation device 2, and the other end is connected to the bottom surface of the floating separation tank 3. The floating separation tank 3 is connected to public sewage or the like via a pipe 31. A valve for controlling the flow rate is provided in the middle of each pipe.

Next, the processing of each unit will be described. The waste liquid flowing out from the rice washing work site, that is, the rice washing waste water, flows into the flocculation tank 1 and is agitated and mixed by the agitation device 10 with the aggregating agent charged according to the inflow amount. As the coagulant, for example, chitosan is used. The bran components present as suspended matter (hereinafter referred to as SS) in the rice rinsing waste water are aggregated by this operation,
Form flocs.

In the fine bubble liquid generator 2, water containing air is pressurized by a pressure pump to dissolve air in water at a high concentration, and the high-concentration air-dissolved high-pressure water is decompressed into the liquid. Fine bubbles are generated and become fine bubble liquid.
As the above-mentioned fine bubble liquid generation device 2, other devices such as those disclosed in, for example, JP-A-5-317847 and JP-A-6-285344 can be used.

In the pipe 20, the fine bubble liquid from the fine bubble liquid generating device 2 is mixed with the rice rinsing wastewater in which the flocs are formed. As a result, air bubbles are adsorbed on the flocs in the waste water after washing and flow into the flotation separation tank 3. In the flotation tank 3,
The flocs are floated by the buoyancy of the bubbles and separated from the liquid to form scum (aggregate solid-liquid separated) 30 on the liquid surface. The scum 30 can be easily collected by a scraper or the like and can be reused as bran.

Next, a description will be given of the results of the implementation of collecting the bran content in the waste water of washing rice by using the above-mentioned bran content recovery device. As the raw water to be treated, rice washing wastewater (SS concentration 900 ppm) generated in the sake brewing process was used. In addition, the processing conditions are as follows. Example A Raw water amount: 5 liters Coagulant: None Coagulant concentration (raw water ratio):-Raw water / bubble liquid mixing ratio: 1/1 Example B Raw water amount: 5 liters Coagulant: Sulfate band ( Flocculant concentration (raw water ratio): 30 ppm Raw water / bubble liquid mixing ratio: 1/2 Example C Raw water amount: 5 liters Coagulant: chitosan (chitosan 0.1%,
Used as an aqueous solution of 0.2% acetic acid) Flocculant concentration (raw water ratio): 30 ppm Raw water / bubble liquid mixing ratio: 1/2 Example D Raw water amount: 5 liter Coagulant: chitosan (chitosan 0.1
%, Used as an aqueous solution of 0.2% acetic acid) Alginic acid Flocculant concentration (raw water ratio): 20 ppm 20 ppm Raw water / bubble liquid mixing ratio: 1/2

Under the above-mentioned processing conditions, the bran content having the values shown below could be collected. Example A: 0.2 g Example B: 3.2 g Example C: 4.2 g Example D: 4.2 g

From the results of the above-mentioned Examples B, C and D,
According to the present invention, it can be seen that the bran content, which could not be collected conventionally, can be collected efficiently.

Further, in the case of Example A in which the coagulant is not mixed with the rice rinsing waste water, the recovered amount of bran is 0.2 g, whereas in the case of Example B in which the coagulant is mixed, 3.2 g is obtained. And the recovery amount is 16 times. Similarly, the recovery amount in each of Examples C and D is 4.2 g, which is 21 times that in Example A. In this way, according to the method of the present invention in which the coagulant is mixed with the rice sewage wastewater to form an agglomerate, and the agglomerates are adsorbed by air bubbles to cause solid-liquid separation, the bran content in the rice sewage wastewater is increased. It can be seen that the recovery rate of can be significantly improved.

FIG. 2 shows the SS of the rice sewage discharged by the above treatment.
The change in concentration is shown. The dotted line in the figure is the upper limit value of general wastewater that can be discharged into public sewage without restriction, and it is possible to purify the rice washing wastewater to below this value in Example C and Example D and to a level close to this value in Example B as well. Recognize.

The acetic acid used in Examples C and D has the effect of solubilizing chitosan. Also,
Example D shows that the use of alginic acid (which controls the size of flocs) to regulate the flocculating action of chitosan does not interfere with the action of the present invention, and to other rice washing effluents requiring adjustment of the flocculating action. This shows that it is possible to cope.

Here, chitosan is an edible flocculant, and acetic acid and alginic acid are edible flocculants. Further, chitosan and alginic acid are added to health foods and the like. Then, when a small amount of the collected bran in Example C and Example D was sampled, it was confirmed that there was no oral irritation and no physical abnormality occurred. Therefore, when such flocculants and coagulant aids are used, the recovered bran is required to be highly safe, as raw materials for biodegradable / biodegradable plastics, feeds, food ingredients, and health food ingredients with high added value. Can be used as.

[0021]

As described above, according to the present invention, it is possible to recover the bran content in the waste water for washing rice, which has not been used conventionally, and reuse it for organic fertilizer, for example. In particular, when chitosan is used as the coagulant, it can be used as a raw material for biodegradable / biodegradable plastics that require high safety for tableware and the like, and as a raw material for foods such as feed and Japanese sweets.
Furthermore, by utilizing the functional food properties of chitosan, it can also be used as a high value-added health food raw material. Moreover, in the present invention, since the bran content in the rice rinsing wastewater is recovered by physicochemical treatment, the treatment time can be markedly shortened as compared with the one utilizing a biological reaction. Moreover, there is no need to bother with the regular supply of microorganisms. Furthermore, since there is no need for an aeration tank or a settling layer for retaining the waste water for washing rice for a long time, there is an advantage that the device configuration can be small.

[Brief description of drawings]

FIG. 1 is a schematic front view showing an example of a bran fraction recovery device used for carrying out the method of the present invention.

FIG. 2 is a graph showing an example of changes in the SS concentration of rice washing wastewater.

FIG. 3 is a schematic front view showing a conventional example of a rice washing wastewater treatment device.

[Explanation of symbols]

 1 Coagulation tank 2 Micro bubble liquid generator 3 Floating separation tank 20 2 Liquid mixing pipe 30 Scum

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C02F 9/00 502 C02F 9/00 502P 502Z

Claims (4)

[Claims] 1. A step of mixing an aggregating agent with the washing rice effluent to form an agglomerate; a step of depressurizing a high-concentration air-dissolved solution by pressurization to generate fine bubbles in the solution; A rice washing wastewater characterized by including a step of mixing the generated washing rice drainage and a solution in which fine air bubbles are generated, floating the aggregates to perform solid-liquid separation, and a step of collecting the floated aggregates 30. Bran recovery method from. 2. A chitosan is used as a flocculant.
The method for collecting bran from the drained rice water. 3. A flocculation tank 1 for producing a flocculate by mixing a flocculant in the washed rice sewage, and depressurizing a high-concentration air-dissolved solution by pressurization to generate fine bubble liquid in the solution. A bran fraction comprising an apparatus 2 and a flotation separation tank 3 that floats an aggregate and separates it into solid and liquid from a mixed liquid of two liquids supplied from the flocculation tank 1 and the fine bubble liquid generation apparatus 2. Recovery device. 4. Chitosan is used as the flocculant.
The bran recovery device described.