JP4831323B2 - How to remove solid components from rice effluent and how to reuse solid components from rice effluent - Google Patents

Description

  The present invention relates to a method for removing a solid component of rice effluent without using a flocculant / precipitation agent, and a method for reusing the removed solid component.

  In sake brewing, food processing industries, etc., large amounts of washed rice wastewater are produced when rice is milled. Furthermore, in recent years, the demand for washed rice, which is referred to as non-washed rice, has increased mainly in the food and drink industry such as ordinary households and fast food and family restaurants. Washed rice wastewater contains organic matter, nitrogen, phosphorus, etc., which causes water pollution. In the washing-free rice production site, washing-free rice production machines have been introduced. As a result, the concentration of washed rice wastewater has increased, the amount of treatment has increased, and the burden of wastewater treatment costs has been increased.

  On the other hand, the rice bran component contained in the washed rice wastewater contains useful substances such as γ-aminobutyric acid (GABA) and its precursor useful amino acids (glutamic acid), phytic acid and inositol, and can be used as a functional food. I can expect. There have also been reports of attempts to positively use starch particles contained in washed rice wastewater as raw materials such as bioethanol and biodegradable plastics.

  For this reason, although various methods for treating washed rice wastewater have been disclosed, the treatment methods include a method of adding solid-liquid separation ability by adding a coagulating precipitant (for example, Patent Document 1), and a filter press. And the like (for example, Patent Document 2) using a filtration process such as the above.

  The invention disclosed in Patent Document 1 is a flocculant for washing wastewater treatment of food, which includes an ion exchange / adsorption component, a coagulation component, and a coprecipitation component. Artificial zeolite is used as an ion exchange / adsorption component, water-soluble aluminum or the like as a coagulation component, and calcium sulfate or the like as a coprecipitation component.

  By the ion exchange function and the adsorption function, the flocculation action on the washed rice waste water is promoted to form agglomerates and adsorb malodorous components generated at that time.

The invention disclosed in Patent Document 2 is a rice effluent treatment apparatus provided with filtering means and cleaning means. As a filtering means, two or more filters with a flexible filter medium and a flexible network are installed in parallel, and the filter is cleaned from one end to the other with a roller to prevent clogging of the filter. Yes.
JP 2002-225513 A JP-A-11-267411

  The flocculant of the invention described in Patent Document 1 contains chlorine, zeolite and the like, and naturally agglomerated precipitates also contain them. For this reason, there is a problem that it cannot be reused as a food material.

  Moreover, in order to prepare the flocculant, a plurality of substances are required, and there remains a problem that the preparation is complicated.

  The invention described in Patent Document 2 requires a filter medium, a cleaning device, and the like, and the device is complicated. In addition to the cost of the apparatus itself, there are disadvantages in that the cost increases due to operating costs, maintenance costs, etc. for treating the washed rice waste water.

  In view of the above matters, an object of the present invention is to remove a solid component of washed rice effluent by a simple method and reuse the removed solid component as a raw material for functional foods and the like.

  The present invention is characterized in that a protease-containing enzyme is added to the rice washing waste water, and the solid components contained in the rice washing waste water are aggregated and settled.

  The present invention is characterized in that an acidic protease is used as the protease-containing enzyme.

  Furthermore, the present invention is characterized in that protease M, protease A, or biozyme is used as the protease-containing enzyme.

  Furthermore, the present invention is characterized in that a metal cation is added to the washed rice waste water.

  Furthermore, the present invention removes the surface protein of the solid component contained in the rice washing wastewater with a protease-containing enzyme to expose the hydroxyl group, and the solid component is aggregated by the bond between the hydroxyl group and the metal ion contained in the rice washing wastewater. It is characterized by making it settle.

  Furthermore, the present invention is characterized in that an acidic protease is used as the protease-containing enzyme.

  Furthermore, the present invention is characterized in that protease M, protease A, or biozyme is used as the protease-containing enzyme.

  Furthermore, the present invention is characterized in that a metal cation is added to the washed rice waste water.

  Furthermore, the present invention adds a protease-containing enzyme to the rice washing waste water, removes the surface protein of the solid component contained in the rice washing waste water, exposes starchy hydroxyl groups to form a negative surface potential, The solid cation is agglomerated by binding metal cations contained in the rice sewage wastewater by electrostatic interaction, and the agglomerated solid component is precipitated by its own weight.

  Furthermore, the present invention is characterized in that the supernatant liquid from which the solid components settled by the solid component sedimentation method of the rice washing wastewater according to any one of claims 1 to 9 is removed is treated as wastewater as it is.

  Furthermore, this invention recycle | reuses the solid component settled by the removal method of the solid component of the rice washing waste water of any one of Claims 1-9 as a raw material of a functional food.

  According to the present invention, the solid components contained in the rice washing wastewater can be easily removed simply by adding the protease-containing enzyme to the rice washing wastewater. The protease-containing enzyme removes the surface protein of the solid component, and the starch-derived hydroxyl group is exposed, and the solid component aggregates due to electrostatic interaction between this hydroxyl group and the metal cation contained in the washed rice effluent. This is because of sedimentation.

  Moreover, the rice washing wastewater originally contains the metal cation involved in the coupling | bonding with a solid component. For this reason, there is an advantage that a solid component can be naturally aggregated and settled without adding a complicated operation or the like only by adding a protease-containing enzyme to the washed rice waste water.

  Furthermore, since an acidic protease having an active pH almost equal to the pH of the rice effluent is used, the surface protein of the solid component of the rice effluent can be efficiently removed, and the solid component can be efficiently aggregated and settled.

  Furthermore, as described above, the present invention has an advantage that a flocculant need not be used as in the prior art because the solid components of the rice effluent can be agglomerated only by adding the protease-containing enzyme to the rice effluent. For this reason, a complicated flocculant is unnecessary and a solid component can also be taken out as it is.

  Furthermore, in the present invention, since it is not necessary to use a filter medium or a cleaning device, an expensive device is not necessary, and an operation cost, a maintenance cost, etc. for treating washed rice waste water are unnecessary. For this reason, the processing of the rice washing waste water is realized at low cost.

  Further, by adding a metal cation, aggregation and sedimentation of the solid components of the washed rice wastewater can be further promoted. This is because if the amount of the metal cation is increased, the bonding with the hydroxyl group of the solid component is promoted.

  Furthermore, the prosthesis-containing enzyme can almost coagulate and settle the organic matter in the washed rice effluent as a solid component, and the supernatant liquid contains almost no organic matter, so the supernatant liquid from which the solid component has been removed from the washed rice effluent can be treated as it is. . Furthermore, the protease-containing enzyme is deactivated after a certain period of time, and no enzyme agent remains in the supernatant.

  Furthermore, the removed solid component can be used as a material for functional foods. In the present invention, a protease-containing enzyme is merely added to the washing waste water without using any flocculant. The protease-containing enzyme is deactivated after a certain period of time. And since no flocculant is used, naturally harmful substances that affect the body are not included. For this reason, only the rice bran component is contained in the removed solid component, and abundantly contained components such as γ-aminobutyric acid and useful amino acids can be effectively reused.

  FIG. 1 is a schematic diagram showing the coagulation and sedimentation mechanism of washed rice wastewater according to the present invention. FIG. 2 is an FT-IR analysis diagram of the solid components of the rice effluent treated according to the present invention. FIG. 3 is a surface potential measurement diagram of the solid components of the rice washing wastewater treated according to the present invention. FIG. 4 is a sedimentation constant measurement diagram showing the effect of addition of a chelating agent on the sedimentation properties of the washed rice wastewater component. FIG. 5 is an enlarged photograph showing the state of aggregation of the solid components of the rice washing wastewater by addition of the protease-containing enzyme of the present invention. FIG. 6 is a sedimentation constant measurement diagram showing the sedimentation property of the solid component of the rice effluent by addition of the protease-containing enzyme of the present invention. FIG. 7 is a sedimentation constant measurement chart showing the effect of the added amount of protease-containing enzyme on the sedimentation properties of the solid components of the washed rice waste water. FIG. 8 is a concentration measurement diagram showing the amount of carbon in the supernatant liquid after the solid component of the rice effluent is settled according to the present invention. FIG. 9 is a process diagram of the apparatus for aggregating and precipitating solid components of the rice washing wastewater according to the present invention.

  FIG. 1 is a schematic diagram showing the aggregation and sedimentation mechanism of solid components contained in the rice washing wastewater according to the present invention.

  In the present invention, the step of adding a protease-containing enzyme to the rice effluent (enzyme addition step) and the removal of the surface protein of the solid component contained in the rice effluent, exposing the starch-derived hydroxyl group to form a negative surface potential A step of forming a negative surface potential, a step of binding the hydroxyl group and the metal cation contained in the washed rice water wastewater by electrostatic interaction, aggregating the solid component, and precipitating the aggregated solid component by its own weight (Coagulation sedimentation step).

  The enzyme addition process will be described.

  Refined white residue, which is a solid component of the waste water for washing rice, contains 50% or more of starch, 10% or more of protein, and mineral content per dry weight. For this reason, the solid component of the rice effluent is fine particles whose surface is covered with protein. Minerals are present as metal cations in the washed rice effluent.

  In this example, the rice-washed wastewater obtained from the washing-free rice processing apparatus (SJR2A type, Satake Co., Ltd.) of the Naka Fukagawa rice mill, Co., Ltd. was used. This rice effluent was discharged when washing-free rice was produced under the conditions of a throughput of 2000 kg / h, an amount of water used (drainage) of 300 l / h, and an operating time of 8 h / day.

  Table 1 shows the basic components of the washed rice wastewater used in this example. The components of the washed rice waste water were analyzed according to the total organic carbon meter (TOC-500, Shimadzu Corporation), and the chemical oxygen demand (COD) was analyzed according to the potassium permanganate method (JIS 0K102). The sludge concentration (MLSS) was measured by the dry weight of the solid component after drying 100 ml of washed rice waste water and removing water.

  Since the total carbon concentration (TC) exceeds 100,000 mg / l and the sludge concentration (MLSS) is also high, it is clear that the waste water contains a large amount of solid components. In this example, TC is used as an index indicating whether or not the solid component in the washed rice wastewater has settled without being dissolved by the protease-containing enzyme.

  Moreover, the COD value of the wastewater normally treated by the activated sludge method is 5000 ppm or less, and this washed rice wastewater exceeds the amount of organic matter that can be decomposed by microorganisms. If treated by the activated sludge process as it is, the organic matter is discharged into the sea area and lakes without being decomposed, and the environment is deteriorated. Furthermore, this waste water is weakly acidic (pH 4.3 to 4.6). For this reason, stepwise pretreatment such as dilution, filtration, neutralization, and centrifugal separation is indispensable drainage before performing the activated sludge treatment method.

  Prepare 100 ml of washing waste water in a polypropylene 150 ml centrifuge tube 120 mm × 16φ (corning 430790, Corning), and add any protease-containing enzyme (0.01-2.0 mg) to acetate buffer (pH 5.0, 0.1 M). It was dissolved in 05 ml, added to the rice effluent, and stirred and mixed thoroughly with a vortex mixer. In the case of fresh rice washing wastewater, the pH is approximately 4.5, so pH adjustment with an acetate buffer is not necessary.

  In this example, as protease-containing enzymes, protease additives (3000 u / mg, Amano Enzyme), protease A (10,000 u / mg, Amano Enzyme), and biozyme, which are enzymes for food additives, are used. M (90 u / mg, Amano Enzyme Co., Ltd.) was subjected to enzyme treatment of washed rice wastewater.

  The enzyme reaction solution was shaken in a reciprocal shaking thermostatic bath (BW201 + BF400 type, Yamato Co., Ltd.) with a shaking speed of 100 rpm and reaction temperatures of 20, 30, 40, and 50 ° C. During the course of the reaction, a uniformly dispersed state was maintained.

The reaction time was 12, 24, 36 hours, the reaction solution after the reaction was allowed to stand for 60 minutes, 120 minutes, the boundary line between the solid component of the sample and the supernatant was measured, and the volume ratio of the solid component in the reaction solution was determined. The sedimentation constant was measured as SV (%). Note that the 60 minutes standing the reaction solution and _{SV 60,} to those allowed to stand for 120 minutes and _{SV 120.}

  In addition, in order to compare the sedimentation properties, a sample containing no protease-containing enzyme (control) was also performed in the same manner.

  Next, the negative surface potential forming step will be described.

  Protease-containing enzymes have the function of decomposing and removing proteins. When a protease-containing enzyme is added to the rice washing wastewater, the surface protein contained in the rice washing wastewater is removed.

  By removing the surface protein, starch such as amylopectin and amylose in the solid component appears on the surface. For this reason, the hydroxyl group which is a starch functional group appears. Since the hydroxyl group has a negative potential, it forms a negative potential on the surface of the solid component.

  FIG. 2 is an FT-IR analysis diagram of a reaction solution treated according to the present invention.

  0.1 g of each protease-containing enzyme was added to 100 ml of washed rice waste water, reacted at 30 ° C. for 24 hours, and then the reaction solution allowed to stand for 60 minutes was analyzed.

  2A is a reaction solution to which protease M is added, FIG. 2B is a reaction solution to which protease A is added, FIG. 2C is a reaction solution to which biozyme is added, and FIG. 2D is an enzyme. It is an analysis figure of the reaction solution (control) which was not added.

In the rice washing wastewater to which the protease-containing enzyme is added, the amount of absorption increases specifically in the vicinity of 3150 cm ⁻¹ . The absorption band near 3150 cm ^{−1 is} an absorption band derived from a hydroxyl group. On the other hand, there is no similar absorption in the control.

  Rice starch is composed of 15-30% amylose and 70-85% amylopectin, but the surface protein of the solid component is removed by a protease-containing enzyme, and the hydroxyl group derived from glucose contained in amylose and amylopectin is removed. It can be confirmed that the surface of the solid component is exposed.

  FIG. 3 shows the surface potential of the reaction solution sediment.

  The sediment component contained in the reaction solution (washed rice wastewater) was collected by centrifugation (11,000 × g, 4 ° C., 10 min), and the surface potential value of the sediment component resuspended and washed with pure water was measured. The surface zeta potential was measured using a microscopic electrophoresis zeta potential measuring device (Zeecom ZC-2000 type, Microtech Nichion Co., Ltd.).

  The negative surface potential of the particle surface of the reaction solution to which the protease-containing enzyme exhibiting sedimentation was added is high. In particular, the surface potential of the rice-washed particle surface layer after treatment with protease M is about -65 mV, while the control that did not show sedimentation is about -35 mV. By adding protease M, formation of a potential difference close to twice that of the control can be confirmed. From these, it can be seen that there is a high correlation (correlation coefficient: r = 0.848) between the sediment of the reaction solution and its surface potential.

  By treating with a protease-containing enzyme, the negative surface potential of the solid component surface layer increases, and the sedimentation volume of the solid component decreases accordingly. From this, it can be seen that the formation of negative charges on the surface layer of the washed rice particles is a direct cause of the acceleration of sedimentation of the solid component.

  The coagulation sedimentation process will be described.

  Polished residue which is a solid component of the rice effluent contains a large amount of metal cations such as silicon, potassium and magnesium. Crosslinking formation and electrostatic repulsion are eliminated by electrostatic interaction between the starch-derived hydroxyl group of the solid component and the metal cation contained in the washed rice effluent. As a result, the solid components aggregate to form macromolecules. The solid component settles due to the weight of the macromolecule.

  FIG. 4 shows the influence of the metal cation contained in the washed rice waste water on the sedimentation property.

  The metal chelating agent concentration in the rice effluent was adjusted to 0, 1, 10, 100, 1000 ppm, 0.1 g of protease-containing enzyme was added to 100 ml of each sample, the reaction was performed as described above, and the sedimentation constant was measured. .

  As metal chelating agents, ethylenediaminetetraacetic acid (EDTA), ethylene glycol bistetraacetic acid (EGTA), 1,10-phenantronium chloride (phenantronium chloride), and deferoxamine mesylate (DFMO) were used.

  EDTA is a chelating agent that forms a complex with various metal ions. EGTA is a chelating agent that selectively forms a complex with Ca ions, phenantronium chloride with Fe (divalent) ions, and DFMO with Fe (trivalent) ions.

  The metal chelating agent concentration of 0 is the washed rice wastewater itself, and the metal cation and solid components contained in the washed rice wastewater combine to show good sedimentation, but as the metal chelating agent concentration increases. In addition, deterioration of the sedimentation constant is observed.

  On the other hand, in the control, no change in sedimentation due to the concentration change of the metal chelating agent is observed.

  From these, it can be seen that the metal chelating agent forms a complex with the metal cation contained in the rice washing wastewater, which inhibits the binding between the solid component of the rice washing wastewater and the metal cation, leading to deterioration of the sedimentation constant.

  In particular, in the reaction solution to which chloride-phenantronium was added, the sedimentation constant increased remarkably as the chloride-phenanthronium concentration increased. This suggests that Fe (divalent) ions have a great influence on the aggregation of the solid components of the washed rice waste water.

  Refined lees contain a large amount of minerals such as silicon, potassium and magnesium. These cation mineral components remove surface layer proteins with protease-containing enzymes, and the solid components of the rice effluent from which the hydroxyl groups are exposed and the metal cations contained in the rice effluent are cross-linked by electrostatic interaction. Turn off electrostatic repulsion. It can be seen that this promotes aggregation and sedimentation.

  Further, when the amount of the metal cation involved in the binding with the solid component increases, aggregation of the solid component is promoted. If many metal cations are involved in the binding, the macromolecules due to the aggregation of the solid components will become larger and the density will also increase. For this reason, if a metal cation is added to the washing waste water and the reaction is carried out with a protease-containing enzyme, the aggregation and sedimentation of solid components can be further promoted.

  FIG. 5 is an enlarged view showing the aggregation state of the solid components of the rice washing wastewater by addition of the protease-containing enzyme of the present invention.

  5A is an enlarged photograph of the control, and FIG. 5B is an enlarged photograph of the reaction solution to which protease M is added. In FIG. 5A, it can be seen that the solid component is dispersed and in the form of fine particles, so that the sedimentation property is remarkably poor. On the other hand, in FIG. 5B, aggregation of solid components is observed. In this way, the solid components of the rice washing wastewater are aggregated to form macromolecules, and thus the sedimentation is promoted by its own weight.

  FIG. 6 is a sedimentation constant measurement diagram showing the sedimentation properties of the solid components of the rice effluent drained by the protease-containing enzyme addition.

  The reaction solution to which the protease-containing enzyme is added has improved sedimentation properties.

  In particular, the reaction solution reacted at 30 ° C. and 40 ° C. showed excellent sedimentation of solid components, and the reaction solution allowed to stand for 24 hours showed the highest sedimentation property.

  Among them, the reaction solution to which protease M was added showed the most favorable value of 43% for the sludge volume when left at a reaction temperature of 30 ° C. for 24 hours, even though the enzyme activity was not so high. It was. The SVI value (sludge capacity index) was 7.2 (ml / g). This value is about 1/7 of the value (56 ml / g) of the activated sludge treatment exhibiting good sedimentation properties, and indicates that the sedimentation performance is superior to that of the activated sludge treatment.

  Protease M is an acidic protease and exhibits high enzyme activity at pH 4.5. Since the pH of the washed rice wastewater is 4.5, which is the same as the active pH, the surface protein of the solid component can be effectively removed even though the number of active enzymes is not so large. For this reason, the outstanding sedimentation property is given.

  Protease A is an enzyme that exhibits a high enzyme activity under the condition of pH 7.0, and has an active pH different from that of washed rice waste water. However, since the number of active enzymes is as large as 10,000 u / mg, it is possible to remove the surface protein of the solid component contained in the washed rice wastewater, and promote aggregation and sedimentation.

  Biozyme M has 150 u / mg and a low number of active enzymes, but shows high sedimentation properties. Biozyme contains α-amylase. α-Amylase has the property of degrading sugar and also acts as a surfactant. For this reason, the bond between the surface protein and the starch is weakened, the surface protein is peeled off, the starch hydroxyl groups are exposed, and the solid components are aggregated and precipitated.

  On the other hand, in the control to which no enzyme was added, no precipitation of solid components was observed after any reaction temperature and reaction time. This also shows that the protease-containing enzyme promotes the precipitation of the solid components of the washed rice waste water.

  In addition, the sedimentation property of the reaction solution that was allowed to stand for 36 hours was worse than that of the reaction solution that was allowed to stand for 24 hours. This is because the rice effluent contains a particle component having starch particles as the core, and when the enzyme treatment is continued for a long time, the starch particles are swollen and solubilized, and the density of the particles becomes close to water. Therefore, it is preferable that the reaction solution is allowed to stand for about 24 hours.

  FIG. 7 shows the influence of the added amount of protease-containing enzyme on the sedimentation properties of the solid components of the washed rice waste water.

  Each sample in which 0.01, 0.05, 0.1, 1.0, and 2.0 g of protease M was added to 100 ml of washed rice waste water was reacted at 30 ° C. for 24 hours in the same manner as described above, and then 60, 120 minutes. The sedimentation constant was measured after standing. When the amount of protease M added is increased, sedimentation of the washed rice wastewater component is promoted. It is clear that the addition of protease M improves the sedimentation properties of the solid components of the washed rice waste water.

  When the amount of protease M added is 1.0 g and 2.0 g, there is not much difference in sedimentation. The amount of enzyme added to 100 ml of settled rice wastewater is preferably 0.1 to 1 mg (3000 u / ml) from the standpoint of sedimentation effect and cost. Moreover, since there is not much difference even if it compares the thing left still for 60 minutes and the thing left still for 120 minutes, if it leaves still for about 60 minutes, a solid component can fully settle.

  With reference to FIG. 8, the supernatant liquid after the solid component of the washed rice waste water has been settled will be described.

  When compared with the sample without the addition of protease M (stock sol), the total amount of carbon (TC) in the supernatant decreases with the amount of protease M added. It can be seen that almost no solid components are dissolved in the supernatant liquid by addition of protease M. From this, the solid components contained in the washing wastewater such as starch granules are settled almost without dissolution due to enzyme addition, and are aggregated and settled at the bottom.

  Moreover, the value is almost the same as the supernatant component (soluble TC component) separated by a centrifuge (11,000 × g, 4 ° C., 10 min), which is not treated with protease-containing enzyme.

  The COD of the supernatant of the reaction solution was 4000 to 5000 ppm. Since this is the amount of organic matter that can be decomposed by microorganisms by a normal activated sludge method, this supernatant can be treated by the activated sludge method. In addition, if it is not discharged into the sea area or lake, it is not subject to legal restrictions and can be discarded as wastewater.

  Protease-containing enzymes are deactivated after a certain period of time. Therefore, since the solid component of the rice washing wastewater removed in the present invention is the rice bran component itself, there is no problem even if it enters the body. Since the rice bran component contains useful components such as γ-aminobutyric acid, glutamic acid, phytic acid and inositol, the removed solid component can be reused as a raw material for functional foods and the like.

  Next, an embodiment of the present invention will be described with reference to FIG. FIG. 9 is a process diagram of the apparatus for aggregating and precipitating solid components of the rice washing wastewater according to the present invention. This apparatus includes a pH adjusting tank 3, an enzyme charging tank 4, and a coagulating sedimentation tank (enzyme reaction tank) 5. Reference numeral 1 generally indicates the present apparatus.

  The coagulation / sedimentation apparatus 1 for solid components contained in this rice effluent is as follows. The rice washing wastewater is introduced into the pH adjustment tank 3 from the rice washing wastewater inlet 2. Here, the pH is adjusted to the set pH by dropwise addition of an acid or alkali solution. After adjusting to a predetermined pH, it is put into the enzyme charging tank 4 and an enzyme agent is added simultaneously. After stirring so that the enzyme is uniformly dispersed in the washing rice wastewater, the rice washing wastewater containing the enzyme agent is poured from the enzyme charging tank to the coagulating sedimentation tank (enzyme reaction tank) 5. Here, the enzyme reaction (proteolysis reaction) and the aggregation / sedimentation of the solid components in the washed rice wastewater proceed simultaneously. Aggregated and settled solid components are collected from the collection valve 6.

  Further, it is discharged from the supernatant liquid discharge port 7. The supernatant liquid can be discarded as it is, but it may be treated and released by a biological treatment apparatus such as an activated sludge apparatus.

  As described above, according to the present embodiment, it is possible to easily settle and recover the solid components in the washed rice waste water without requiring a centrifugal separator or a filtration device.

  By simply adding protease-containing enzymes to the rice washing wastewater, the solid components contained in the rice washing wastewater can be easily removed. Moreover, the solid component contained in the removed rice effluent contains useful amino acids and can be reused for health foods. For this reason, use in washing-free rice manufacturing industry, wastewater treatment industry, food manufacturing industry, etc. can be expected.

It is a schematic diagram which shows the aggregation and sedimentation mechanism of the solid component of the rice washing waste_water | drain by this invention. It is a FT-IR analysis figure of the solid component of the rice washing wastewater processed by this invention. It is a surface potential measurement figure of the solid component of the rice washing wastewater processed by the present invention. It is a sedimentation constant measurement figure which shows the influence of the chelating agent addition on the sedimentation property of the rice washing wastewater component. It is an enlarged photograph which shows the aggregation state of the solid component of the rice washing waste_water | drain by addition of the protease containing enzyme of this invention. It is a sedimentation constant measurement figure which shows the sedimentation property of the solid component of the rice washing waste_water | drain by addition of the protease containing enzyme of this invention. It is a sedimentation constant measurement figure which shows the influence of the addition amount of the protease containing enzyme which affects the sedimentation property of the solid component of the rice washing waste_water | drain. It is a density | concentration measurement figure which shows the carbon content of the supernatant liquid after making the solid component of the rice washing waste_water | drain settle by this invention. It is process drawing which shows one Embodiment of the removal method of the solid component of the rice washing waste_water | drain by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coagulation sedimentation apparatus 2 Rice washing drainage inlet 3 pH adjustment tank 4 Enzyme introduction tank 5 Coagulation sedimentation tank (enzyme reaction tank)
6 Recovery valve 7 Supernatant discharge port

Claims (11)

  A method for removing solid components from rice washing wastewater, comprising adding a protease-containing enzyme to the rice washing wastewater, and aggregating and precipitating the solid components contained in the rice washing wastewater.   The method for removing solid components from washed rice effluent according to claim 1, wherein acidic protease is used as the protease-containing enzyme.   The method for removing a solid component of rice effluent according to claim 1, wherein protease M, protease A, or biozyme is used as the protease-containing enzyme.   2. The method for removing solid components from rice washing wastewater according to claim 1, wherein a metal cation is added to the rice washing wastewater. The protease-containing enzyme removes the surface protein of the solid component contained in the rice washing wastewater to expose the hydroxyl group,
A method for removing a solid component of rice effluent, wherein the solid component is aggregated and settled by a bond between the hydroxyl group and metal ions contained in the rice effluent.   6. The method for removing solid components from washed rice effluent according to claim 5, wherein acidic protease is used as the protease-containing enzyme.   The method for removing a solid component of rice effluent according to claim 5, wherein protease M, protease A, or biozyme is used as the protease-containing enzyme.   6. The method for removing solid components from rice washing wastewater according to claim 5, wherein metal cations are added to the rice washing wastewater. Add protease-containing enzyme to the washed rice effluent,
Removing the surface protein of the solid component contained in the rice effluent, exposing the starch-derived hydroxyl group to form a negative surface potential;
The solid component is aggregated by binding the hydroxyl group and the metal cation contained in the washed rice waste water by electrostatic interaction,
A method for removing a solid component from waste water for washing rice, wherein the aggregated solid component is settled by its own weight.   A method for removing a solid component of rice washing wastewater, wherein the supernatant liquid from which the solid component settled by the method for removing the solid component of rice washing wastewater according to any one of claims 1 to 9 is treated as wastewater as it is. .   A method for reusing a solid component of rice effluent, wherein the solid component precipitated by the method for removing a solid component of rice effluent according to any one of claims 1 to 9 is reused as a raw material for functional food. .

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