JP2010012446A - Fat and oil containing waste water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste water treatment apparatus capable of degrading fat and oil contained in organic waste water at a high degree and satisfactorily treating the organic waste water. <P>SOLUTION: The waste water treatment apparatus 10 for treating fat and oil containing waste water includes: a fat and oil separating means 3 which separates fat and oil from the waste water and obtains separation water having the reduced content of fat and oil; an upper counterflow anaerobic treatment tank 8 for methane-fermenting organic material contained in the separation water; a fat and oil decomposition tank 5 which stores the fat and oil separated by the fat and oil separating means 3 and fungus body for decomposing the fat and oil and decomposes the fat and oil; a precipitation tank (solid-liquid separation means) 6 for separating treatment liquid discharged from the fat and oil decomposition tank 5 into a solid content 6a and a liquid content 6b; and a solid content return line L7 for returning the solid content 6a to the fat and oil decomposition tank 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for treating organic wastewater containing fats and oils.

  As wastewater treatment methods using microorganisms, an aerobic treatment method using an aerobic bacterium and a methane fermentation treatment method (anaerobic treatment method) using an anaerobic bacterium are generally known. The aerobic treatment method requires energy for blowing air into the water to be treated, whereas the methane fermentation treatment method consumes less energy and can also obtain biogas mainly composed of methane. For this reason, the methane fermentation treatment method is said to be advantageous in terms of energy efficiency over the aerobic treatment method. One of the advantages of the methane fermentation treatment method is that the amount of excess sludge generated is small.

  Various types of upward flow anaerobic treatment tanks have been developed to treat high-load wastewater containing organic substances at high concentrations by the methane fermentation treatment method. For example, a processing tank using a UASB (Upflow Anaerobic Sludge Blanket) method or an improved EGSB (Expanded Glanular Sludge Bed) method is known. These upward-flow anaerobic treatment tanks can store granular sludge called granular sludge in the tank, and the organic matter is made efficient by flowing the treated water upward while in contact with the granular sludge. Is broken down.

  By the way, when treating organic wastewater containing fats and oils with granule sludge, the fats and oils adhere to the granule sludge, which tends to reduce the contact efficiency between the wastewater and the granule sludge, resulting in insufficient treatment of organic matter. . As means for solving such a problem, in Patent Document 1 below, prior to introducing the water to be treated into the upward flow type anaerobic treatment tank, oil is separated from the water to be treated, and this is separated by lipase producing bacteria. An anaerobic treatment device that decomposes is described.

Patent Document 2 below describes that higher fatty acids produced by the decomposition of fats and oils become an inhibiting factor for methane fermentation. From the viewpoint of preventing this, the concentration of higher fatty acids in the anaerobic treatment tank is controlled. A method for treating fat and oil-containing wastewater is described.
JP 2005-270862 A JP 2001-321792 A

  According to the anaerobic treatment apparatus described in Patent Document 1, since oil and fat can be separated in the upstream stage of the upward flow type anaerobic treatment tank, the contact efficiency caused by the fat and oil being introduced into the upward flow type anaerobic treatment tank. Can be prevented in advance. However, the anaerobic treatment apparatus still has room for improvement in terms of further decomposing oil and fat.

  In other words, bacterial cells that produce enzymes that degrade fats and oils (hereinafter referred to as “enzyme-producing bacteria”) generally have poor self-aggregation properties and sedimentation properties, and therefore have the property of easily flowing out of the decomposition tank together with the treated water. If the concentration of the enzyme-producing bacteria in the tank falls below a certain level, the fats and oils are not decomposed and flow into the subsequent anaerobic treatment tank, or the methane fermentation treatment is inhibited in the anaerobic treatment tank. There is a possibility that the higher fatty acid concentration which may be a factor becomes high.

  This invention is made | formed in order to solve the said subject, and it aims at providing the waste water treatment apparatus which decomposes | disassembles the fats and oils contained in organic waste water highly, and can fully process organic waste water.

  The fat and oil-containing wastewater treatment apparatus according to the present invention is for treating organic wastewater containing fats and oils, and separates fats and oils from the organic wastewater and obtains separated water in which the content of fats and oils is reduced. Oil and fat separation means, an upflow anaerobic treatment tank for methane fermentation treatment of organic matter contained in the separated water, oil and fat separated by the oil and fat separation means and cells for decomposing this are contained, An oil and fat decomposition tank for decomposing, a solid-liquid separation means for separating the treatment liquid discharged from the oil and fat decomposition tank into a solid content and a liquid content, and a solid content return line for returning the solid content to the oil and fat decomposition tank.

  According to the wastewater treatment apparatus having the above-described configuration, the enzyme-producing bacteria that have flowed out together with the treatment liquid from the fat and oil decomposition tank can be returned to the fat and oil decomposition tank by the solid-liquid separation means and the solid content return line. Since the concentration of enzyme-producing bacteria can be sufficiently maintained in the oil and fat decomposition tank, the oil and fat can be decomposed to a sufficiently high degree.

  As described above, since the fat and oil can be highly decomposed by the treatment in the fat and oil decomposition tank, the water to be treated in which the content of the fat and oil is sufficiently reduced can be supplied to the upward flow type anaerobic treatment tank. Thereby, in the upward flow type anaerobic treatment tank, problems caused by oils and fats adhering to biological sludge can be prevented in advance. Therefore, the upward flow type anaerobic treatment tank can sufficiently exhibit its treatment capacity and can be operated at a high load.

  Moreover, it is preferable that the oil-and-fat-containing wastewater treatment apparatus according to the present invention further includes a first liquid transfer line that transfers the liquid separated by the solid-liquid separation unit to the upstream side of the oil-separation unit. Since the liquid component separated by the solid-liquid separation means is transferred to the upstream side of the oil separation means by the first liquid content transfer line, the oil remaining in the liquid is separated by the oil separation means and sent to the oil decomposition tank. And will be supplied again. By going through such a process, the fats and oils contained in the water to be treated can be decomposed sufficiently sufficiently.

  The oil and fat-containing wastewater treatment apparatus according to the present invention is a second liquid component that transfers the liquid separated by the solid-liquid separation means to the downstream side of the oil and fat separation means and to the upstream side of the upward flow type anaerobic treatment tank. It may be provided with a transfer line. The wastewater treatment apparatus is suitable for treating organic wastewater with a relatively small content of fats and oils. The second liquid transfer line provided in the wastewater treatment apparatus is for supplying the liquid to the upward flow anaerobic treatment tank, whereas the first liquid provided in the wastewater treatment apparatus described above. The minute transfer line is for supplying the liquid component to the oil separation means. The structure and effect of the wastewater treatment apparatus are the same as those of the above-described wastewater treatment apparatus, except that the transfer destination of the liquid component separated by the solid-liquid separation means is different.

  In this invention, it is preferable that an oil-fat decomposition tank is equipped with the means to add an alkali with respect to the to-be-processed liquid in a tank. By adding an alkali to the liquid to be treated, the fats and oils are easily dispersed in the liquid to be treated, the contact efficiency between the enzymes and fats produced by the enzyme-producing bacteria is improved, and the decomposition rate of the fats and oils is improved.

The alkali added to the liquid to be treated in the oil / fat decomposition tank is preferably calcium hydroxide. By adding calcium hydroxide to the liquid to be treated, in addition to the effect of improving the dispersibility of fats and oils, there is an effect that the activity of the fat-degrading enzyme is enhanced by Ca ²⁺ generated by the ionization of calcium hydroxide.

In addition, by adding calcium hydroxide to the liquid to be treated, carbon dioxide in the fat and oil decomposition tank reacts with Ca ²⁺ to produce insoluble calcium carbonate. When this calcium carbonate adheres to the enzyme-producing bacteria, the specific gravity of the enzyme-producing bacteria increases. If it does so, it will become difficult to flow out an enzyme production microbe from an oil-and-oil decomposition tank. Moreover, since the sedimentation property of the outflowing enzyme-producing bacteria is also improved, a sedimentation tank or the like can be adopted as a solid-liquid separation means, and the separation and recovery can be performed efficiently. Furthermore, calcium carbonate produced by the reaction between carbon dioxide and Ca ²⁺ in the upward flow type anaerobic treatment tank is generated and adheres to the biological sludge in the tank. This makes it difficult for the biological sludge to float and flow out, and enables a more stable methane fermentation process.

  According to the oil and fat-containing wastewater treatment apparatus, organic wastewater containing fats and oils can be treated by the following method. That is, the apparatus separates fats and oils from organic wastewater, and at the same time, separates the fats and oils to obtain separated water with a reduced content of fats and oils, and the methane fermentation treatment of the organic matter contained in the separated water. An anaerobic treatment step performed in the treatment tank, and an oil and fat decomposition step in which the fat and oil separated in the fat and oil separation step are introduced into the fat and oil decomposition tank containing the cells for decomposing the fat and oil, and the fat and oil decomposition treatment is performed. A solid-liquid separation process that separates the treatment liquid discharged from the fat and oil decomposition tank into a solid content and a liquid content, a solid content return process that returns the solid content to the fat and oil decomposition tank, and a liquid content that is transferred through a liquid content transfer line. The wastewater treatment method comprising the liquid component and the liquid component transfer step of mixing the organic wastewater before the oil separation step or the separated water after the oil separation step can be carried out.

  According to said waste water treatment method, the enzyme producing microbe which flowed out with the process liquid from the fats and oils decomposition tank can be returned in the said tank by passing through a solid-liquid separation process and a solid content return process. Since the concentration of enzyme-producing bacteria can be sufficiently maintained in the oil and fat decomposition tank, the oil and fat can be decomposed to a sufficiently high degree.

  As described above, since the fats and oils can be highly decomposed by the treatment in the fat and oil decomposition tank, the water to be treated whose oil content is sufficiently reduced can be supplied to the upward flow anaerobic treatment tank. Thereby, in the upward flow type anaerobic treatment tank, problems caused by oils and fats adhering to biological sludge can be prevented in advance. Therefore, the upward flow type anaerobic treatment tank can sufficiently exhibit its treatment capacity and can be operated at a high load.

  The destination of the liquid component separated in the solid-liquid separation step, that is, whether the liquid component is mixed with the organic waste water before the fat separation step or the separated water after the fat separation step is the fat concentration contained in the raw water It can be appropriately selected according to the above.

  According to the present invention, fats and oils contained in organic waste water can be highly decomposed to sufficiently treat organic waste water.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

(Oil containing wastewater treatment equipment)
FIG. 1 is a diagram showing a configuration of a wastewater treatment apparatus according to a preferred embodiment of the present invention. The wastewater treatment apparatus 10 includes a front-stage oil / fat pretreatment unit 10a and a rear-stage anaerobic treatment unit 10b. The oil pretreatment unit 10 a includes an adjustment tank 2, an oil separation means 3, an oil decomposition tank 5, and a precipitation tank (solid-liquid separation means) 6. On the other hand, the anaerobic treatment unit 10 b includes an acid generation tank 7 and an upward flow type anaerobic treatment tank 8. Hereinafter, each component will be described.

  The adjustment tank 2 of the fat pretreatment unit 10a is for temporarily storing oil-containing wastewater (hereinafter, simply referred to as “drainage” in some cases) and adjusting the amount of water transferred to the oil separation means 3. The adjustment tank 2 is connected to a line L1 for introducing wastewater (raw water) and a line L2 for transferring the wastewater to the oil separation means 3. The amount of waste water transferred from the adjustment tank 2 to the oil separation means 3 is adjusted according to the treatment capacity of the waste water treatment apparatus 10. The adjustment tank 2 may have a function of removing impurities contained in the waste water.

  The oil / fat separation means 3 is for separating the oil / fat contained in the wastewater supplied through the line L2. Devices applicable as the oil separation means 3 are, for example, a pressure levitation device, a normal pressure levitation device, an oil / water separator, an oil trap, and the like. The oil separation means 3 is connected to a line L3 for transferring the separated water in which the oil content is reduced to the oil decomposition tank 5 and a line L4 for transferring the separated oil to the acid generation tank 7.

  The fat and oil decomposition tank 5 is for decomposing oil and fat supplied through the line L3. The oil / fat decomposition tank 5 can accommodate the liquid to be treated and the enzyme-producing bacteria in the tank. The fat and oil decomposition tank 5 includes an alkali storage tank 5a that contains alkali (for example, calcium hydroxide aqueous solution) to be added to the liquid to be treated in the tank, and a line L5 that transfers the alkali in the alkali storage tank 5a to the fat and oil decomposition tank 5. Is provided. In this embodiment, an alkali addition means is comprised by the alkali storage tank 5a and the line L5. In addition, what is necessary is just to adjust the addition amount of an alkali with the pump (not shown) etc. with which the line L5 is provided in the middle.

  Moreover, the fat and oil decomposition tank 5 includes a circulation pump 5b for returning the liquid to be treated near the water surface into the line L3 and supplying it into the liquid phase. There is an advantage that the fats and oils can be efficiently decomposed by supplying the fats and oils easily floating on the water surface repeatedly into the liquid tank in the tank by the circulation pump 5b. Further, the oil and fat decomposition tank 5 includes a diffuser plate 5c for supplying air into the tank and a blower 5d for supplying air to the diffuser plate 5c. A line L6 for transferring the treatment liquid to the precipitation tank 6 is connected to the fat and oil decomposition tank 5.

  The settling tank 6 is for separating the treatment liquid from the fat and oil decomposition tank 5 into a solid content 6a and a liquid content 6b. The sedimentation tank 6 has a structure that allows solids to settle by gravity and concentrate the solids 6a at the bottom of the tank. The solid content 6a separated by the settling tank 6 can be returned to the fat and oil decomposition tank 5 through a line (solid content return line) L7. Thereby, the enzyme production microbe of the fats-and-oils decomposition tank 5 is maintained at high density. On the other hand, the liquid part 6b discharged from the settling tank 6 is transferred to the upstream side of the oil separation means 3 through a line (liquid part transfer line) L8. The liquid component transferred to the upstream side of the fat separation means 3 is again introduced into the fat separation means 3. In addition, the line L7a is branched in the middle of the line L7, so that an excess of enzyme-producing bacteria and the like can be discharged appropriately.

  The separated water that has undergone the treatment in the oil pretreatment unit 10a is discharged from the oil separation unit 3 and transferred to the anaerobic treatment unit 10b through the line L4.

  The acid generation tank 7 of the anaerobic treatment unit 10b is for converting an organic substance contained in the separated water discharged from the oil separation means 3 into an organic acid. The organic substance contained in the separated water is an organic substance such as a fatty acid generated by the treatment in the fat pretreatment unit 10a, or an organic substance other than the fat contained in the raw water. The acid production tank 7 can accommodate separated water and acid-fermenting bacteria. The acid generation tank 7 is connected to a line L9 that supplies the separated water that has been subjected to the acid fermentation process to the upward flow anaerobic treatment tank 8.

  The upward flow anaerobic treatment tank 8 (hereinafter simply referred to as “treatment tank 8”) is for subjecting the organic acid obtained by the treatment in the acid generation tank 7 to methane fermentation. Examples of the treatment tank applicable as the treatment tank 8 include a UASB type reaction tank and an EGSB type reaction tank. The treatment tank 8 can accommodate water to be treated and granule sludge 8a. A line L9 is connected to the lower part of the treatment tank 8, and the water to be treated flows upward while contacting the granule sludge 8a in the tank.

  Near the liquid surface of the treatment tank 8, a line L10 for discharging the treatment liquid that has undergone the methane fermentation treatment is connected. On the other hand, a line L11 for discharging biogas containing methane gas generated by the methane fermentation process is connected to the upper part of the processing tank 8.

(Treatment method for oil-containing wastewater)
Next, a method for treating fat and oil-containing wastewater using the wastewater treatment apparatus 10 will be described.

  First, fat and oil containing waste water (raw water) is introduced into the adjustment tank 2 through the line L1. Once drainage is stored in the adjustment tank 2, a predetermined amount of drainage is introduced into the oil separation means 3 through the line L <b> 2. In addition, the fat and oil containing waste water from the adjustment tank 2 and the liquid component from the line L8 are introduced into the fat and oil separation means 3 through the line L2.

  In the oil separation means 3, oil and fat are separated from the organic waste water, and separated water having a reduced content of oil and fat is obtained (oil separation process). In order to efficiently perform the oil and fat decomposition treatment in the oil and fat decomposition tank 5 at the subsequent stage, it is preferable to concentrate the oil and fat in the oil and fat separation means 3 to a high concentration. From this point of view, the ratio (A / B) between the flow rate A of the oil containing fat discharged from the line L3 and the flow rate B of separated water discharged from the line L4 is about 1/5 to 1/20. preferable.

  The liquid containing the fats and oils separated by the fats and oils separating means 3 is introduced into the fats and oils decomposition tank 5, while the separated water in which the content of fats and oils is reduced is introduced into the acid generation tank 7.

  In the fat and oil decomposition tank 5, the fats and oils are decomposed (oil and fat decomposition step). It introduce | transduces into the fat-and-oil decomposition tank 5 which accommodated the enzyme producing microbe through the line L3, and the enzyme and fats and oils which an enzyme producing microbe contacts by contacting with the circulation pump 5b, and decomposes fats and oils. By blowing air from the diffuser plate 5c into the tank, the enzyme-producing bacteria can easily grow, and the effect of improving the decomposition rate of fats and oils can be obtained. It is preferable to break down fats and oils into glycerol and fatty acids (about 16 to 18 carbon atoms) by treatment in the fat and oil decomposition tank 5. The fatty acids are not limited to those having about 16 to 18 carbon atoms, but may include those lower than this (15 or less carbon atoms).

  It is preferable that the concentration of the enzyme-producing bacteria in the liquid to be treated stored in the oil / fat decomposition tank 5 is 2000 to 5000 mg / L. By maintaining the concentration of the enzyme-producing bacteria within the above range, a lipase necessary for the decomposition of fats and oils can be sufficiently generated. In this case, the fat concentration (n-hexane extract substance concentration) of the liquid to be treated is preferably about 1000 to 20000 mg / L.

  In the fat and oil decomposition step, calcium hydroxide (alkali) is added to the liquid to be treated in the fat and oil decomposition tank 5 through the line L5. From the viewpoint of increasing the decomposition efficiency of fats and oils, the pH of the liquid to be treated is preferably 6.0 to 9.5, more preferably 7.0 to 9.0 by adding calcium hydroxide. .

  The treatment liquid that has undergone the treatment in the fat and oil decomposition tank 5 is introduced into the precipitation tank 6 through a line L6. In the settling tank 6, the processing liquid discharged from the fat and oil decomposition tank 5 is separated into a solid content and a liquid content (solid-liquid separation step). The solid content 6a containing the enzyme-producing bacteria at a high concentration is returned to the fat and oil decomposition tank 5 through the line L7 (solid content returning step). By returning the enzyme-producing bacteria contained in the solid content 6a, the enzyme-producing bacteria in the oil decomposing tank 5 can be held at a high density.

  On the other hand, the liquid component 6b discharged from the settling tank 6 is transferred through the line L8, and the liquid component 6b and the waste water in the line L2 are mixed (liquid component transfer process). By transferring the liquid component 6b to the upstream side of the oil separation means 3, the oil remaining in the liquid component 6b can be supplied again to the oil separation means 3 and the oil decomposition tank 5, and the oil and fat can be further enhanced. Can be disassembled.

Moreover, according to this embodiment, the following effects A to E can be obtained.
A. By returning the solid content 6a to the fat and oil decomposition tank 5 through the line L7, the enzyme-producing bacteria in the fat and oil decomposition tank 5 can be maintained at a high concentration.
B. When the liquid to be treated is made weakly alkaline, the fats and oils are easily transferred to the emulsification system, and an emulsion state in which the fats and oils are dispersed in the liquid to be treated can be easily formed. As a result, the contact efficiency between the oil and fat and the oil-degrading enzyme is increased, and the oil and fat decomposition rate is improved.
C. In an emulsified system in which fats and oils are emulsified, it is said that the activity of lipase is higher than in non-emulsified systems, and the degradation rate of fats and oils is improved.
D. Since Ca ²⁺ generated by ionization of calcium hydroxide has a function of enhancing the activity of lipase, the decomposition of fats and oils in the fat and oil decomposition tank 5 is promoted.
E. In the fat and oil decomposition tank 5, it reacts with Ca ²⁺ and carbon dioxide to produce insoluble calcium carbonate. When this calcium carbonate adheres to an enzyme-producing bacterium, the specific gravity of the enzyme-producing bacterium floc increases. As a result, the enzyme-producing bacteria are less likely to flow out from the fat and oil decomposition tank 5, and the outflowed enzyme-producing bacteria can be efficiently separated and recovered by the precipitation tank 6. Therefore, it becomes easier to keep the enzyme-producing bacteria in the oil / fat decomposition tank 5 at a high concentration.

  The separated water discharged from the fat and oil separation means 3 through the treatment in the fat and oil pretreatment unit 10a is supplied to the anaerobic treatment unit 10b in the subsequent stage, and the organic matter contained in the separated water is decomposed.

  First, the separated water discharged from the oil separation means 3 is introduced into the acid generation tank 7 through the line L4. The separated water contains glycerin and fatty acids generated by the decomposition of fats and oils, or organic substances other than the fats and oils contained in the raw water. In the acid generation tank 7, the organic matter is decomposed into an organic acid such as a fatty acid having 6 or less carbon atoms by acid fermentation treatment.

  In addition, also in the acid production | generation tank 7, the following effects are show | played by adding calcium hydroxide (alkali) in the oil-and-oil decomposition tank 5 of the front | former stage, and adjusting pH to the alkaline side. That is, when weakly alkaline separation water is supplied to the acid generation tank 7, higher fatty acids that are difficult to disperse in water are easily transferred to the emulsification system, and an emulsion state in which higher fatty acids are dispersed in water to be treated can be easily formed. Therefore, the contact efficiency between the higher fatty acid and the acid-fermenting bacterium is increased, the higher fatty acid is decomposed into the intermediate fatty acid, and the middle-lower fatty acid is further lowered.

  Next, the separated water that has undergone the acid fermentation treatment in the acid production tank 7 is introduced into the treatment tank 8 through the line L9. In the treatment tank 8, an organic matter contained in the water to be treated is subjected to methane fermentation treatment (anaerobic treatment step). While the water to be treated rises from the lower part to the upper part of the tank, it comes into contact with the granular sludge 8a, and organic acids such as intermediate fatty acids are decomposed by methane fermentation. In the treatment tank 8, problems caused by oil and fat adhering to the granular sludge 8a can be prevented in advance. Therefore, the processing tank 8 can fully exhibit its processing capacity, and high load operation is also possible.

  The water to be treated in the treatment tank 8 preferably has a pH of 6 to 9, more preferably 6.5 to 8.5, from the viewpoint of suitably performing a decomposition treatment with a methanogen.

In addition, also in the processing tank 8, the following effects by having added calcium hydroxide in the oil-and-oil decomposition tank 5 of the front | former stage are show | played. That is, in the treatment tank 8, Ca ²⁺ and carbon dioxide contained in the separated water supplied through the line L4 react to produce insoluble calcium carbonate. The calcium carbonate adheres to the granular sludge 8a, whereby the specific gravity of the granular sludge 8a increases. As a result, the granule sludge 8a is less likely to float and flow out, and a more stable methane fermentation process is possible.

  Further, the treatment in the treatment tank 8 tends to be unstable when the water to be treated contains a lot of suspended solids. In this regard, since the separated water supplied to the treatment tank 8 through the line L4 has been subjected to the treatment in the oil separation means 3 and the precipitation tank 6, the SS flowing into the treatment tank 8 has a sufficiently low concentration. Therefore, the anaerobic treatment can be stably performed in the treatment tank 8.

  The treated water discharged from the treatment tank 8 through the line L10 is discharged after being subjected to a necessary treatment according to the water quality standard or application of the discharge destination. The biogas discharged through the line L11 can be used as energy through a desulfurization process or the like.

  According to this embodiment, the fats and oils contained in organic waste water can be decomposed | disassembled highly by the process in the fat pre-processing part 10a. For this reason, the separated water in which the content of fats and oils is sufficiently reduced can be supplied to the subsequent anaerobic treatment unit 10b. Therefore, the processing tank 8 of the anaerobic processing unit 10b can sufficiently exhibit its processing capability, and can sufficiently decompose organic substances.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment. For example, the structure shown in FIG. 2 may be sufficient as the waste water treatment apparatus which concerns on this invention.

  FIG. 2 is a block diagram showing another embodiment of the waste water treatment apparatus according to the present invention. The waste water treatment apparatus 20 shown in the figure has the above-described waste water in that the liquid component 6b separated in the sedimentation tank 6 is transferred to the downstream side of the oil separation means 3 and the upstream side of the treatment tank 8 through the line L18. It differs from the processing apparatus 10.

  The destination of the liquid component 6b, that is, whether the liquid component 6b is mixed with the organic waste water before the fat separation step or the separated water after the fat separation step is appropriately selected according to the fat concentration in the raw water. What is necessary is just to be able to switch a transfer destination suitably. As shown in FIGS. 1 and 2, the lines L8 and L18 for transferring the liquid components communicate with the settling tank 6 and the lines L2 and L4, respectively, but the liquid transferred through the line L8 or the line L18. The portion may be directly supplied to the fat separation means 3 or the acid generation tank 7.

  Moreover, in the said embodiment, although the case where the precipitation tank 6 was used as a solid-liquid separation means was illustrated, you may use a centrifuge etc. instead of this. However, it is more advantageous in terms of energy consumption and cost to use the sedimentation tank 6 than to use a centrifuge.

  Furthermore, the alkali added to the liquid to be treated in the fat and oil decomposition tank 5 is not limited to calcium hydroxide, and magnesium hydroxide, sodium hydroxide, potassium hydroxide and the like may be used. And calcium hydroxide may be used in combination. Further, a part of the treated water discharged from the treatment tank 8 may be returned to the acid generation tank 7. Depending on the degree of decomposition in the fat and oil decomposition tank 5 and the properties of the raw water, the acid generation tank 7 may not necessarily be installed. In this case, the separated water from the oil separation means 3 may be directly introduced into the treatment tank 8.

[Decomposition experiment of oil-containing water]
Synthetic waste water having the composition shown in Table 1 was prepared, and the synthetic waste water was decomposed.

(Experimental example 1)
The synthetic waste water 0.1L and the microorganism preparation (manufactured by Gate Co., Ltd., trade name: GS-I) were put into a container having a capacity of 0.5L. Then, decomposition | disassembly experiment of oil-containing water was done by stirring over 24 hours at the temperature of 30 degreeC. During the experiment, calcium hydroxide was appropriately added so that the pH of the water to be treated in the container was 9. When the inside of the container after the decomposition experiment was visually observed, no oil film remained, and as a result of measuring the fat content by the normal hexane extraction method, the fat content that was initially 3000 mg / L became 300 mg / L, The fat was fully decomposed.

(Experimental example 2)
The synthetic waste water was decomposed in the same manner as in Experimental Example 1 except that calcium hydroxide was appropriately added so that the pH of the water to be treated was 7. When the inside of the container after the decomposition experiment was visually observed, no oil film remained, and the fats and oils were sufficiently decomposed.

(Experimental example 3)
The synthetic waste water was decomposed in the same manner as in Experimental Example 1, except that calcium hydroxide or hydrochloric acid was appropriately added so that the pH of the water to be treated was 5. When the inside of the container after the decomposition experiment was visually observed, residual oil was observed.

(Experimental example 4)
The synthetic waste water was decomposed in the same manner as in Experimental Example 1 except that sodium hydroxide was added instead of calcium hydroxide so that the pH of the water to be treated was adjusted to 9. When the inside of the container after the decomposition experiment was visually observed, no oil film remained, and as a result of measuring the fat content by the normal hexane extraction method, the fat content that was initially 3000 mg / L was 500 mg / L, The fat was fully decomposed.

  From the above experiment, it can be confirmed that calcium hydroxide is more suitable as an alkali to be added than sodium hydroxide.

It is a block diagram which shows suitable embodiment of the waste water treatment equipment which concerns on this invention. It is a block diagram which shows other suitable embodiment of the waste water treatment equipment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Oil separation means, 5 ... Oil decomposition tank, 6 ... Precipitation tank (solid-liquid separation means), 6a ... Solid content, 6b ... Liquid content, 7 ... Acid production tank, 8 ... Upflow anaerobic processing tank, DESCRIPTION OF SYMBOLS 10,20 ... Waste water treatment apparatus, 10a ... Oil pretreatment part, 10b ... Anaerobic treatment part, L7 ... Solid content return line, L8 ... Liquid content transfer line.

Claims (4)

A wastewater treatment device for treating organic wastewater containing fats and oils,
While separating fats and oils from the organic waste water, fats and oils separating means for obtaining separated water in which the content of fats and oils is reduced,
An upward flow type anaerobic treatment tank for methane fermentation treatment of organic matter contained in the separated water;
Containing an oil and fat separated by the oil and fat separating means and a fungus body for decomposing the oil and fat, and an oil and fat decomposition tank for decomposing the oil and fat;
Solid-liquid separation means for separating the treatment liquid discharged from the fat and oil decomposition tank into a solid content and a liquid content;
A solid content return line for returning the solid content to the fat decomposition tank;
An oil-containing wastewater treatment apparatus comprising:   The oil / fat-containing wastewater treatment apparatus according to claim 1, further comprising a liquid part transfer line for transferring the liquid part to the upstream side of the oil / fat separation means.   The oil-and-fat-containing wastewater treatment apparatus according to claim 1 or 2, wherein the oil / fat decomposition tank includes means for adding alkali to the liquid to be treated in the tank.   The fat and oil-containing wastewater treatment apparatus according to claim 3, wherein the alkali is calcium hydroxide.

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