JPS60212286A - Treatment of rice washing water - Google Patents

Abstract

PURPOSE:To enhance treatment effect, by simple operation such that reverse osmosis treatment is applied to rice washing water by a tubular type membrane module to fractionate and concentrate suspended substances and org. substances contained in rice washing water. CONSTITUTION:Rice washing water (a) is stored in a storage tank 1 and sent to a membrane module 3 by a pressure pump 2 before returned to the storage tank 1 through a pressure valve 4. In the recirculation process reaching (d) from (a), when pressure to the membrane module 3 is raised by adjusting the opening degree of the pressure valve 4, the solvent (water) in the rice washing water transmits a RO membrane and discharged out of the system as clean water (c). When this operation is succeeded, the rice washing water stored in the storage tank 1 is steadily reduced in its quantity and conc. The concentrate remaining in the storage tank 1 at last is taken out of the system as a conc. liquid (b) by switching over a three-way vavle 5.

Description

[Detailed Description of the Invention] This invention provides 1! j, relates to a treatment method for fractionating and concentrating turbid substances and organic substances using a tubular RO membrane module or an ultrafiltration membrane module.

An object of the present invention is to provide a method for fractionating rice washing water that has a simple structure, requires less labor for operation, and has a high treatment effect.

Washing rice water is rice cake pieces. This rice cake piece contains a large amount of suspended solids and organic matter, and is characterized by being cloudy.

Currently, the activated sludge method is the main method used to treat washed rice water, and there are other methods such as the force υ pressure flotation method and the coagulation sedimentation method. There is a lot of room for improvement. The difficulty in treating rice washing water is due to the large amount of suspended organic matter. Therefore, we thought that if we could reduce these organic substances in some way, it would make subsequent treatment easier, and we investigated that method. As a result, we decided to utilize fractionation processing using an RO membrane module and an ultrafiltration membrane module.

The RO membrane module was developed in the United States about 30 years ago for the purpose of desalinating seawater. Since then, research has been carried out vigorously in the United States, Europe, and Japan to put this into practical use, and today large-scale water supply plants with a capacity of 100,000 or 17 days have been constructed.

RO membranes and ultrafiltration membranes are thin film-like substances that have countless extremely fine pores ranging from microns to angstroms in size, and various ions and molecules dissolved in the solution pass through these extremely fine pores. Alternatively, suspended fine substances are separated (referred to as fractionation) by pressure. These films have a thickness of around 100 to 200 μm,
The cross-section of the membrane consists of an extremely thin skin layer with a thickness of less than 1 μm, and this skin layer is supported by an outer sponge layer. ROIIU is usually 40-60kg/
cot G and ultrafiltration membrane is 5-10 kg/cm2
Used under pressure conditions of G. These membranes are weak in strength and cannot withstand high pressure as is. Therefore, these membranes are protected with a suitable support and housed in a hard case so that they can withstand high pressure conditions.The membrane protected with this support is called a membrane module. There are various shapes of membrane modules, and they can be roughly divided into tubular (tubular), capillary (hollow fiber), and spiral (
4 types: roll-shaped) and plate-and-frame (flat membrane)
There are different types. Capillary type module has a diameter of 0.2
Thousands of hollow, thread-like membranes about the size of ~2 dragons are bundled together and housed in a single cylindrical case. A spiral type module is a sheet-like membrane rolled up into a cylindrical case and housed in a cylindrical case. A plate-and-frame module is made by stacking dozens of flat membrane sheets and tightening them into a box shape. The tubular module is a tubular membrane housed in a pipe-shaped FRP case with a coin-sized diameter. Kibilary, Spiral,
Plate-and-frame modules have the advantage of being compact in terms of equipment because they have a large membrane area per unit volume, but on the other hand, the membrane is easily contaminated, especially if it contains large floating objects or suspended solids. The membrane becomes clogged and cannot withstand long-term use. In this regard, since the tubular type module has a tubular membrane with a coin-sized diameter, it will not become clogged even if suspended matter is contained, and dirt on the membrane can be easily removed. In particular, since the permeation treatment using the membrane module is a loss-flow type as shown in Figure 1, there is no accumulation of solids or cakes on the separation membrane compared to total filtration methods such as filter cloth or sand filtration. , it will not become clogged even if a large amount of suspended water passes through it.

The present inventor focused on the above-mentioned basic knowledge regarding membrane modules and the characteristics of tubular type modules that are difficult to block, and came up with the idea of fractionating rice washing water containing a lot of splitting substances using tubular type membrane modules. .

When treating rice washing water with a membrane module, we encountered the following problems.

The problem is blockage of the membrane module caused by suspended solids in the wastewater. As mentioned above, there are four types of RO membrane modules: millet, spiral, plate and frame, and tubular. The suitability of the module for water treatment was not well understood. Therefore, in order to examine this problem, we conducted experiments on various membrane modules and found the following.

As a result, ■ Capillary, spiral, and plate-and-frame type modules are unable to withstand long-term use due to the Q'l'FJ substance clogging between the membranes.

■The tubular module has two points: it does not get blocked and can withstand long-term use. The next issue concerns the pressure conditions for the membrane module. First, before explaining this problem, the reverse osmosis principle of membrane modules will be explained. Now, as shown in Figure 2, when salt water and pure water are introduced with a reverse osmosis membrane (semi-permeable membrane) as a boundary, the water passes through the RO membrane and moves to the salt water side (a). This movement of water creates a difference in the height of the liquid level on both sides, and when it reaches a certain height, the water stops moving (mouth). The phenomenon in which the solvent moves across the RO membrane from the side of low concentration to the side of high concentration is called an osmotic phenomenon, and the pressure corresponding to the difference in liquid level produced on both sides is called osmotic pressure. Therefore, when a pressure higher than the above-mentioned osmotic pressure is applied to the saline side, water moves from the saline side to the water side, and the saline solution becomes concentrated (c). This is called reverse osmosis.
Based on this principle, the operation of applying pressure to a solution to move the solvent is called reverse osmosis treatment or permeation treatment. Therefore, the pressure conditions applied to the reverse osmosis membrane depend on the osmotic pressure of the solution, and the higher the solute concentration, the higher the pressure required. Rice washing water contains various organic substances and suspended solids and has a high concentration, so it requires high pressure conditions.

Therefore, we considered using various membranes depending on the purpose of treating the washed rice water.

Membranes include reverse osmosis membranes (RO) depending on the size of the substances to be separated.
) and ultrafiltration membranes (UF).

RO membranes separate ions and molecules from several angstroms to hundreds of angstroms in size, while UF membranes separate molecules and particles from several tens of angstroms to several microns in size.

Normally the pressure condition of RO membrane is 20-60kg/+ffl
G, UF membranes are used at 10 kg/crAG or less.

First, when removing suspended solids from rice washing water, use an ultra-4 filtration membrane that has a rough membrane and can be processed at low pressure, and when fractionating both suspended solids and organic matter, use RO
We decided to use a membrane.

As described above, the purpose of this invention is to further improve the treatment effect by developing a method of treating rice washing water by reverse osmosis and a treatment method using a tubular RO membrane module.

That is, the gist of the configuration of the present invention is as follows.

A method for treating washed rice water, which comprises subjecting the washed rice water to reverse osmosis treatment using a tubular type RO membrane module to fractionate and concentrate suspended solids and organic matter contained in the washed rice water. and a method for treating washed rice water, which comprises permeating the washed rice water using a tubular type ultrafiltration membrane module to fractionate and concentrate U-layer substances (contained in the washed rice water).

The rice washing water referred to in this invention refers to rice powder and rice cake pieces discharged from the process of washing polished rice with water. Its concentration,
The degree of contamination is not particularly specified, and it may be in a dilute state by adding water. Various chemicals are used during processing (neutralizing agents, oxidizing agents, disinfectants, adsorbents, surfactants, etc.)
It is free to add, and heating and cooling are also free. Furthermore, it is also possible to freely combine coagulation-sedimentation, pressure flotation, screening, etc. as a pre-processing step.

Next, the configuration of the present invention will be explained using examples. Third
The figure shows the configuration of the present invention in a flow sheet manner. In the figure, A indicates the rice washing water that should be concentrated, and the opening indicates the concentrated rice washing water. In this series of processes from the mouth to the mouth,
First, rice washing water is stored in the storage tank 1, and then sent to the tank 11 by the pressure pump 2, and then the pressure valve 4 is connected to the storage tank 1.
Return to Qj71.

During the circulation process from A to II, when the pressure to the membrane module 3 is increased by adjusting the opening degree of the pressure valve 4, the solvent (water) in the rice washing water permeates the RO membrane, and the clear water is and is discharged from the system. As this operation continues, the rice washing water stored in storage tank 1 becomes more and more NIL and becomes concentrated. Finally, the concentrate remaining in the storage tank 1 is taken out of the system through the B condensation port by switching the three-way valve 5.

Examples of the present invention are given below.

Example 1 Rice washing water discharged from a sake brewery was collected and used at a working pressure of 35 kg/c using a tubular RO membrane module.
The rice was subjected to reverse osmosis treatment with taG, and the properties of the undiluted solution, permeated water, and concentrated solution were measured as shown in Table 1. Using membrane module, working pressure 8 k
Reverse osmosis treatment was performed using g/cot G, and the properties of the stock solution, permeated water, and concentrated solution were measured, and the results were as shown in Table 2.

The effects of this invention will be explained below. The purpose of this invention is to concentrate the rice washing water, and the purpose is to establish a method for treating the rice washing water that is simple in structure, requires little labor, and has high processing efficiency. First, Table 3 shows a comparison between this invention and conventional biochemical methods.
It is understood that the present invention is highly effective in terms of operability and economy.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a permeation model of a membrane module. FIG. 2 is an explanatory diagram showing the reverse osmosis principle of an RO membrane. FIG. 3 is an explanatory diagram illustrating an example of the method according to the present invention in the form of a flow sheet. A is raw water, mouth is concentrated water, C is clear water, 2 is circulating water, ■ is a storage tank, 2 is a pressure pump, 3 is a tubular type (RO, UF) membrane module, 4 is a pressure valve, 5 is a three-way valve, 6 is a flow meter, 7.8 is a pressure gauge. Table 3 Comparison between the method of the invention and the activated sludge method Figure 1
Difference between RO membrane filtration and total volume filtration method ◎ One type with one cross tube. . . . Permeate. . ◎Total filtration method % formula % () 1. Indication of incident Patent Application No. 69235 of 1982 2.
Title of the invention: 61c Rice water treatment method 3. Relationship with the case of the person making the amendment: Patent applicant 4. Date of amendment order: July 11, 1980 6. Contents of the amendment "As attached" 4. Brief drawings Explanation FIG. 1 is an explanatory diagram showing a permeation model of a membrane module. (A) is a cross-flow method, (B) is a total filtration method, A is the stock solution, the opening is the concentrated liquid, C is the permeate, the second is the cake, and the l is R.
O membrane, 2 is a filtration membrane. FIG. 2 is an explanatory diagram showing the reverse osmosis principle of an RO membrane. (A), (B), and (C) are phase diagrams of reverse osmosis, A is water, N is saline, 1 is the RO membrane, P is osmotic pressure, P2 is reverse osmotic pressure, and p is pressure. FIG. 3 is an explanatory diagram illustrating an example of the method according to the present invention in the form of a flow sheet. A is raw water, mouth is concentrated water, C is clear water, 2 is circulating water, ■ is a storage tank, 2 is a pressure pump, 3 is a tubular type (RO, UF) membrane module, 4 is a pressure valve, 5 is a three-way valve, 6 is a flow meter, 7.8 is a pressure gauge. Figure 1 (A),''. Figure 2 (A) (

Claims (1)

[Claims] (11 Contained in the rice washing water by subjecting it to reverse osmosis treatment using a tubular RO membrane module)
A method for treating washed rice water, which is characterized by fractionating and concentrating turbid substances and organic substances. (2) A method for treating washed rice water, which comprises permeating the washed rice water using a tubular type ultrafiltration membrane module to fractionate and concentrate suspended substances contained in the washed rice water.