JP2018069145A - Method and device for biological treatment of oil and fat-containing wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for biological treatment of oil and fat-containing wastewater capable of decomposing oils and fats in the oil and fat-containing wastewater and suppressing generation of an oil ball.SOLUTION: The method for biological treatment of the oil and fat-containing wastewater comprises, in the biological treatment of the oil and fat-containing wastewater in which a concentration ratio of calcium to a normal hexane extract is equal to or larger than 0.02 in a biological treatment tank 12, adding an iron salt to the oil and fat-containing wastewater using an iron salt supplying equipment 14 so that a concentration ratio of iron to the calcium in the oil and fat-containing wastewater becomes equal to or larger than 0.1.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a biological treatment method and biological treatment apparatus for fat and oil-containing wastewater.

  In the biological treatment of wastewater containing a large amount of oil and fat, such as wastewater from food factories, the generation of oil balls causes oil balls to accumulate in the treatment system and increase sludge disposal costs, or the oil balls flow out together with the treated water. The water quality may deteriorate. The oil ball is a combination of a fatty acid produced by decomposition of fats and oils by lipase or the like, which is a degrading enzyme in microorganisms, and inorganic components such as calcium and magnesium. In particular, many of the oil balls generated from wastewater from food factories are calcium-bound fatty acid calcium (see, for example, Non-Patent Document 1).

“Water and Wastewater”, Vol. 56, no. 5, 2014

  Therefore, an object of the present invention is to provide a biological treatment method and biological treatment apparatus for fat and oil-containing wastewater that can decompose oil and fat in the fat and oil-containing wastewater and suppress the generation of oil balls.

  The present invention is a biological treatment method for fat-containing wastewater that biologically treats oil-containing wastewater having a calcium concentration ratio of 0.02 or more with respect to the normal hexane extract, wherein iron is contained in the fat-containing wastewater. It is a biological treatment method of fat and oil containing wastewater which adds an iron salt to the said fat and oil containing wastewater so that the density | concentration ratio may become 0.1 or more.

  Moreover, the biological treatment method of the oil-containing wastewater is suitable for the treatment of oil-containing wastewater having a calcium concentration of 10 mg / L or more in the oil-containing wastewater.

  Moreover, the biological treatment apparatus for fat and oil-containing wastewater according to the present invention comprises a biological treatment tank for biologically treating fat and oil-containing wastewater having a calcium concentration ratio of 0.02 or more with respect to a normal hexane extract material, and an iron salt in the fat and oil-containing wastewater. Iron salt addition means to be added, and the iron salt supply means includes an iron salt in the fat and oil containing waste water so that a concentration ratio of iron to the calcium in the fat and oil containing waste water is 0.1 or more. Is a biological treatment device for oil-containing wastewater to which is added.

  Moreover, the biological treatment apparatus of the said fat and oil containing wastewater is suitable for the treatment of the fat and oil containing wastewater whose calcium concentration in the said fat and oil containing wastewater is 10 mg / L or more.

  According to the present invention, the oil and fat in the oil and fat-containing waste water can be decomposed and the generation of oil balls can be suppressed.

It is a schematic diagram which shows an example of a structure of the fat and oil containing waste water treatment apparatus which concerns on this embodiment. It is a schematic diagram which shows another example of the structure of the fat-and-oils containing waste water treatment equipment which concerns on this embodiment. It is a figure which shows the result of the amount of oil balls which generate | occur | produced in Experimental example 1. FIG. It is a figure which shows the result of the fats-and-oils decomposition speed of Experimental example 2.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  Drawing 1 is a mimetic diagram showing an example of the composition of the oil-and-fat containing waste water treatment equipment concerning this embodiment. The oil-and-fat-containing wastewater treatment apparatus 1 shown in FIG. 1 includes an adjustment tank 10, a biological treatment tank 12, and an iron salt supply device 14 as an example of iron salt supply means. A drainage introduction pipe 16 is connected to the drainage inlet of the adjustment tank 10, one end of the drainage discharge pipe 18 is connected to the drainage outlet of the adjustment tank 10, and the other end of the drainage discharge pipe 18 is connected to the drainage inlet of the biological treatment tank 12. And a treated water discharge pipe 20 is connected to a treated water outlet (not shown) of the biological treatment tank 12.

  Although not shown in the figure, the adjustment tank 10 and the biological treatment tank 12 include a heating device (heating means) such as an electric heater that heats the water temperature in the tank, and an aeration device (aeration device) that aerates the inside of the tank. Means), a biopharmaceutical addition device (biological product addition means) that adds biologics to the tank to control the amount of organisms in the tank, and an acid or alkali added to the tank to control the pH in the tank It is desirable to appropriately install a pH adjusting device (pH adjusting means) or the like.

  The iron salt supply device 14 includes a storage tank 22 and an iron salt supply pipe 24. In the present embodiment, as shown in FIG. 1, one end of the iron salt supply pipe 24 is connected to the iron salt discharge port of the storage tank 22, and the other end of the iron salt supply pipe 24 is connected to the iron salt supply port of the adjustment tank 10. It is connected. The iron salt supply pipe 24 is provided with a valve (not shown) or a pump (not shown) for adjusting the amount of iron salt added.

  Next, the operation of the fat and oil-containing wastewater treatment apparatus 1 according to this embodiment will be described.

  Oil-containing wastewater having a calcium concentration ratio with respect to the normal hexane extract material of 0.02 or more is supplied to the adjustment tank 10 through the wastewater introduction pipe 16. Then, the iron salt passes through the iron salt supply pipe 24 from the storage tank 22 and is supplied to the adjustment tank 10. Here, the iron salt is added to the adjustment tank 10 so that the concentration ratio of iron to calcium in the fat and oil-containing wastewater is 0.1 or more. Specifically, the calcium concentration of the waste water in the adjustment tank 10 is measured by a Ca densitometer, and the iron salt supply pipe 24 valve, pump, or the like so that the iron concentration satisfies the above range with respect to the measured value. Is controlled and the supply amount of iron salt is adjusted.

  The oil-containing wastewater to which the iron salt is added so that the concentration ratio of iron to calcium is 0.1 or more is supplied from the drainage discharge pipe 18 to the biological treatment tank 12. The presence of an iron salt in the oil-containing wastewater above the predetermined amount not only has the effect of nutrients that promote the growth of oil-degrading microorganisms in the tank, but also the fatty acids produced by the oil-decomposition and calcium in the wastewater. It also has an effect of suppressing the binding of. Therefore, in the biological treatment tank 12, when the oil-containing wastewater and the oil-decomposing microorganism contact with each other in the presence of the iron salt, the oil-and-fat in the oil-containing wastewater is decomposed and oil balls generated by the oil-and-oil decomposition are generated. Can be effectively suppressed. In this way, the wastewater treated in the biological treatment tank 12 is discharged out of the system from the treated water discharge pipe 20 as treated water.

  Below, an example of the process conditions of the fat and oil containing waste water treatment equipment 1 which concerns on this embodiment is demonstrated.

  The oil and fat-containing wastewater may be drainage of any origin, and examples thereof include kitchen wastewater, edible oil production plant wastewater, meat processing plant wastewater, and confectionery production plant wastewater.

  In the fat-containing wastewater, when the concentration ratio of calcium to the normal hexane extract is 0.02 or more, the generation of oil balls due to the decomposition of fats and oils becomes remarkable in normal biological treatment. In particular, when the concentration ratio is satisfied and the calcium concentration in the oil-containing wastewater is 10 mg / L or more, the generation of oil balls becomes more remarkable. However, according to the treatment of this embodiment, even when the concentration ratio of calcium to the normal hexane extract material and the calcium concentration satisfy the above range, it is possible to effectively suppress the generation of oil balls due to oil decomposition. It becomes. The treatment of the present embodiment is particularly effective for oil-containing wastewater having a calcium concentration ratio of 0.02 to 0.1 and a calcium concentration of 10 mg / L to 100 mg / L.

  The oil / fat concentration in the oil / fat-containing wastewater to be treated is preferably in the range of 200 to 3000 mg / L in terms of the normal hexane extract substance concentration. When the normal hexane extract substance concentration in the oil-and-fat-containing wastewater exceeds 3000 mg / L, biological treatment will take a lot of time and may not be practical. Moreover, in this embodiment, since the pressurization floating process for removing fats and oils is not necessarily required beforehand, an installation can be simplified and processing cost can also be reduced. Furthermore, due to the action of nutrient salts of iron salts, oxidation catalysts, etc., expensive oil-degrading microorganisms and oil-degrading enzymes are not necessarily required for the decomposition of fats and oils, so that the processing cost can be further reduced.

  The normal hexane extractable substance is a component mainly composed of fats and oils extracted to the normal hexane side by mixing fat and oil-containing waste water and normal hexane. The normal hexane extract material is charged with an appropriate amount of fat and oil-containing wastewater into the separatory funnel (about 100 to 1000 ml depending on the fat and oil content of the wastewater), and after the methyl orange solution is added dropwise, the color of the solution changes to red. Hydrochloric acid was added dropwise until repeated, and 40 ml of normal hexane was added and shaken vigorously for 2 minutes twice. After separating only the normal hexane layer, filtration and dehydration were carried out. It is obtained by volatilization.

  The amount of iron salt added is not particularly limited as long as the concentration ratio of iron to calcium in the fat-containing wastewater is 0.1 or more, but the amount of oil balls generated can be further reduced. And preferably 0.2 or more. The amount of iron salt added in the treatment of the present embodiment is larger than the amount of iron salt added in the treatment considering only normal oil decomposition. For example, when the calcium concentration in the wastewater is 10 mg / L and the concentration ratio of calcium to the normal hexane extract is 0.02, the normal hexane extract in the wastewater is 500 mg / L. In such wastewater, when the treatment of the present embodiment is applied, the amount of iron salt added is 1 mg / L or more, but in the treatment considering only fat and oil decomposition, addition of iron salt of 1/2 or less than that The amount is sufficient. Thus, by adding a large amount of iron salt to the fat-and-water containing waste water, it becomes possible to decompose the fat and oil in the fat-and-oil containing waste water and to suppress the generation of oil balls.

  There is no restriction | limiting in particular as iron salt to add, Ferrous chloride, ferric chloride, poly ferric sulfate etc. can be used, and 1 type may be used individually or 2 or more types may be used together. These iron salts may be powder, slurry, solution, or the like.

  The pH of the oil-containing wastewater may be in the range of any of the acidic side (for example, pH 4 or lower), near neutral (for example, pH 7 to 8), or alkaline side (for example, pH 9 or higher) in terms of the effect of suppressing oil balls. From the point of further improving the growth of microorganisms in the presence of water, the point that the final treated water can be efficiently neutralized and discharged out of the system, etc. It is preferable to adjust to weak alkalinity, for example, it is preferable to adjust to pH 6-9, and it is more preferable to adjust to pH 6.5-7.5.

  The biological treatment in the biological treatment tank 12 may be either an aerobic treatment or an anaerobic treatment, and may be appropriately selected according to the properties of the waste water. When aerobic treatment is performed, an aeration apparatus is installed in the biological treatment tank 12 and oxygen is supplied so that the dissolved oxygen concentration in the biological treatment tank 12 is 0.5 mg / L or more. Preferably, oxygen is supplied so as to be 1.0 mg / L or more.

  The residence time of the fat-containing wastewater in the biological treatment tank 12 may be set as appropriate depending on the properties of the fat-containing wastewater, and is not particularly limited. For example, it is preferably in the range of 6 hours to 48 hours. .

  From the viewpoint of maintaining the amount of microorganisms in the biological treatment tank 12, it is preferable to put a commercially available microorganism preparation into the biological treatment tank 12. In addition, in order to maintain the amount of microorganisms in the biological treatment tank 12, a microorganism carrier such as a sponge carrier, a gel carrier, a hollow cylinder, or a fibrous carrier is introduced into the biological treatment tank 12 to immobilize the microorganisms. It is also preferable to use the method to do.

  In this embodiment, although it is the 2 tank structure of the adjustment tank 10 and the biological treatment tank 12, it is not limited to this tank structure, For example, a single tank structure may be sufficient. In the case of a single tank, for example, a predetermined amount of iron salt may be supplied to the biological treatment tank 12 and biological treatment may be performed in the biological treatment tank 12. However, from the viewpoint of more effectively suppressing the oil balls, a tank (for example, the adjustment tank 10 shown in FIG. 1) for contacting the fat-containing wastewater and the iron salt is provided in the previous stage of the biological treatment tank 12 from the single tank configuration. A two-tank configuration or a multiple-tank configuration is preferred.

  FIG. 2 is a schematic diagram illustrating another example of the configuration of the oil-and-fat-containing wastewater treatment apparatus according to the present embodiment. In the fat and oil-containing wastewater treatment apparatus 2 shown in FIG. 2, the same components as those in the fat and oil-containing wastewater treatment apparatus 1 shown in FIG.

  The oil-and-fat-containing wastewater treatment apparatus 2 shown in FIG. 2 includes a raw water tank 26 and a pressurized levitation tank 28. A drainage introduction pipe 16 a is connected to the drainage inlet of the raw water tank 26, one end of the drainage introduction pipe 16 b is connected to the drainage outlet of the raw water tank 26, and the drainage inlet pipe 16 b is connected to the drainage inlet of the pressurized levitation tank 28. The ends are connected. Further, one end of the oil / fat introduction pipe 16 c is connected to the oil / fat outlet of the pressurized levitation tank 28, and the other end of the oil / fat introduction pipe 16 c is connected to the oil / fat inlet of the adjustment tank 10. One end of a fat / oil discharge pipe 16 d is connected to the fat / oil outlet of the adjustment tank 10, and the other end of the fat / oil discharge pipe 16 d is connected to the fat / oil inlet of the biological treatment tank 12. One end of a drainage discharge pipe 16 e is connected to the drainage outlet of the pressurized levitation tank 28, and the other end of the drainage discharge pipe 16 e is connected to the drainage inlet of the biological treatment tank 12. A treated water discharge pipe 20 is connected to the.

  Next, operation | movement of the fat and oil containing waste water treatment equipment 2 which concerns on this embodiment is demonstrated.

  The fat and oil-containing wastewater is stored in the raw water tank 26 from the wastewater introduction pipe 16a. The fat and oil-containing wastewater in the raw water tank 26 is introduced into the pressurized levitation tank 28 from the drainage introduction pipe 16b, and a pressurized levitation process is performed. The floss containing fats and oils floats on the liquid surface in the pressure levitation tank 28 by the pressure levitation process. This fat and oil floss is introduced into the adjusting tank 10 from the fat and oil introduction pipe 16c, and the predetermined amount of iron salt described above is added. The fat and oil floss to which the iron salt is added is introduced into the biological treatment tank 12 from the fat and oil discharge pipe 16d, and the wastewater from which the fat and oil has been removed in the pressurized levitation tank 28 is transferred from the drainage discharge pipe 16e to the biological treatment tank 12. be introduced. And in the biological treatment tank 12, fats and oils are biologically treated in the presence of an iron salt. In addition, the above-described predetermined amount of iron salt suppresses the generation of oil balls caused by fat and oil decomposition. The treated water thus biologically treated is discharged from the treated water discharge pipe 20. Since suspended substances may remain in the treated water, a filter 30 is installed near the treated water outlet of the biological treatment tank 12 to remove suspended substances in the treated water, and then the treated water discharge pipe. It is desirable to discharge from 20.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Reference example>
For food factory wastewater 1 to 8 having different Ca concentration and normal hexane extractable substance concentration, biological treatment was carried out for 24 hours at a water temperature of 20 degrees and an initial pH of 7 to confirm the occurrence of oil balls. The results are shown in Table 1.

  As shown in Table 1, oil balls are generated even when the food factory wastewater 1 having a Ca / n-hexane extract (Ca / n-Hex) concentration ratio of 0.016 and a Ca concentration of 9 mg / L is biologically treated. I did not. However, when the food factory wastewaters 2 to 8 having a higher Ca / n-Hex concentration ratio and Ca concentration than the food factory wastewater 1 were biologically treated, oil balls were generated.

<Experimental example 1>
The wastewater from the sugar beet production factory was used as the fat and oil containing wastewater to be treated. Regarding the water quality of the wastewater, the CODcr concentration was 2000 mg / L, the normal hexane extract substance concentration was 400 mg / L, and the calcium concentration was 20 mg / L. The drainage and ferrous chloride were put into a sealed screw mouth glass bottle. The amount of ferrous chloride added was 0 (no iron salt added), 0.1, 0.2, 0.3, or 0.4 in terms of Fe / Ca concentration ratio.

  After the iron salt addition, biological treatment was performed for 72 hours at a water temperature of 20 ° C. and an initial pH of 7.2. After the biological treatment, an oil ball that floated on the liquid surface was collected and dried at 105 degrees, and the dry weight was defined as the amount of oil ball. Using the amount of oil balls generated when the Fe / Ca concentration ratio is 0 (no addition of iron salt) as the reference (100%), the Fe / Ca concentration ratio is 0.1, 0.2, 0.3, or 0.00. The amount of oil balls in case 4 was determined. The result is shown in FIG.

  As shown in FIG. 3, by adding ferrous chloride so that the Fe / Ca concentration ratio is 0.1, the amount of generated oil balls is 45% compared to the case where ferrous chloride is not added. It became possible to reduce. In particular, by adding ferrous chloride so that the Fe / Ca concentration ratio is 0.2 or more, the amount of generated oil balls is reduced by 63% or more compared to the case where ferrous chloride is not added. It became possible.

<Experimental example 2>
The wastewater from the sugar beet production factory was used as the fat and oil containing wastewater to be treated. Regarding the water quality of the wastewater, the CODcr concentration was 2000 mg / L, the normal hexane extract substance concentration was 400 mg / L, and the calcium concentration was 20 mg / L. The drainage and ferrous chloride were put into a sealed screw mouth glass bottle. The addition amount of ferrous chloride was not added (Fe / Ca: 0), 0.15 mg / L (Fe / Ca: 0.0075), 0.7 mg / L (Fe / Ca: 0.035), 1 4 mg / L (Fe / Ca: 0.07), 2.0 mg / L (Fe / Ca: 0.1), 4.0 mg / L (Fe / Ca: 0.2).

  After the iron salt addition, biological treatment was performed for 72 hours at a water temperature of 20 ° C. and an initial pH of 7.2. The amount of oxygen consumed as a result of fat / oil decomposition was recorded, and the amount of oxygen consumed per hour (oil / oil decomposition rate) was determined. The result is shown in FIG.

  As shown in FIG. 4, when ferrous chloride is added so that the iron concentration becomes 0.15 mg / L (Fe / Ca: 0.0075), compared to the case where ferrous chloride is not added, When adding ferrous chloride so that the oil and fat decomposition rate is about twice as high and the iron concentration is 0.7 mg / L (Fe / Ca: 0.035), compared to the case where ferrous chloride is not added. Thus, the oil and fat decomposition rate was about 3 times. However, even when ferrous chloride was added so that the iron concentration was 0.7 mg / L or more, an increase in the fat and oil decomposition rate was not confirmed. Moreover, when ferrous chloride was added so that it might become 0.7 mg / L (Fe / Ca: 0.035), the amount of oil balls equivalent to ferrous chloride non-addition had generate | occur | produced.

  From the above, by adding an iron salt so that the concentration ratio of iron to calcium is 0.1 or more, to the fat-containing wastewater whose concentration ratio of calcium to normal hexane extract is 0.02 or more, It can be said that fats and oils can be efficiently decomposed and generation of oil balls can be effectively suppressed.

  DESCRIPTION OF SYMBOLS 1, 2 Fat and oil containing waste water treatment apparatus, 10 adjustment tanks, 12 biological treatment tanks, 14 iron salt supply apparatus, 16, 16a, 16b drainage introduction pipe, 16c fats and oils introduction pipe, 16d fats and oils discharge pipe, 16e, 18 drainage discharge pipes, 20 treated water discharge pipe, 22 storage tank, 24 iron salt supply pipe, 26 raw water tank, 28 pressurized flotation tank, 30 filter.

Claims (4)

A biological treatment method for fat-containing wastewater for biologically treating fat-containing wastewater having a calcium concentration ratio of 0.02 or more to normal hexane extract,
A biological treatment method for fat and oil-containing wastewater, wherein iron salt is added to the fat and oil-containing wastewater so that the concentration ratio of iron to the calcium in the fat and oil-containing wastewater is 0.1 or more.   The biological treatment method of fat and oil containing wastewater according to claim 1, wherein the calcium concentration in the fat and oil containing wastewater is 10 mg / L or more. A biological treatment tank for biologically treating fat and oil-containing wastewater having a concentration ratio of calcium to normal hexane extract of 0.02 or more;
An iron salt addition means for adding an iron salt to the oil-containing wastewater,
The oil-containing wastewater characterized in that the iron salt supply means adds iron salt to the oil-and-fat-containing wastewater so that the concentration ratio of iron to the calcium in the oil-and-fat-containing wastewater is 0.1 or more. Biological treatment equipment. The biological treatment apparatus for fat and oil-containing wastewater according to claim 3, wherein the calcium concentration in the fat and oil-containing wastewater is 10 mg / L or more.