JP7284598B2 - Anaerobic treatment system and control method for anaerobic treatment system - Google Patents

Description

TECHNICAL FIELD The present invention relates to an anaerobic treatment system for treating oil-containing wastewater and a control method for the anaerobic treatment system.

Biological treatment using various microorganisms is generally known as a method for treating waste water containing organic matter. In particular, biological treatment in an anaerobic environment (hereafter referred to as "anaerobic treatment") is widely used due to its advantages such as no need for aeration power and almost no excess sludge. .
On the other hand, in the biological treatment of oil-containing wastewater, poorly water-soluble substances such as oils and fats are difficult to be decomposed by microorganisms, and reactions do not readily proceed. In addition, free fatty acids such as higher fatty acids produced during the reaction are known to inhibit the metabolism of microorganisms. Therefore, in the biological treatment of oil-containing wastewater, it is necessary to reduce the amount of oil in the wastewater.

As a method for reducing fats and oils in fat-containing wastewater, it is known to use bacteria that are excellent in fat decomposition (hereinafter referred to as "oil-degrading bacteria").

In Patent Document 1, in the treatment of oil-containing wastewater, digested sludge collected from a methane fermentation tank is treated with an oil-containing medium to separate and culture anaerobic oil-degrading bacteria, and the cultured anaerobic oil-degrading bacteria are treated with oil-containing wastewater. A method for decomposing fats and oils in wastewater containing fats and oils, which is grown in a methane fermentation tank to be fed, is described.

JP-A-8-182998

In the treatment method described in Patent Document 1, there is a problem that the cost and time required for culture in the medium are enormous because the lipid-degrading bacteria are cultured once in the medium. Therefore, in order to improve the treatment efficiency of oil-containing wastewater, it is required to efficiently grow and maintain oil-degrading bacteria in the anaerobic treatment tank without relying on culture medium.

On the other hand, the concentration of fats and oils flowing into the anaerobic treatment tank is not constant due to fluctuations in production items and production volumes in factories, etc., which are sources of fat-containing wastewater. At this time, when low-concentration fats and oils flow in for a long period of time as fat-containing wastewater, the growth of bacteria that are excellent in decomposing other components contained in the wastewater is prioritized, and the fat-degrading bacteria are eliminated. In addition, when high-concentration fats and oils flow in as fat-containing wastewater after that, there is a problem that fat-decomposing bacteria cannot grow in time and fat-degrading performance deteriorates.

An object of the present invention is to suppress the reduction of fat-degrading bacteria in the anaerobic treatment tank against fluctuations in the fat concentration of fat-containing wastewater in the anaerobic treatment of fat-containing wastewater, and to stably maintain fat-degrading performance. An object of the present invention is to provide an anaerobic treatment system and a control method for the anaerobic treatment system.

As a result of intensive studies on the above-mentioned problems, the present inventors provided an oil-water separation tank for separating fats and oils in the fat-containing wastewater in the anaerobic treatment of fat-containing wastewater, adjusted the degree of separation of the fats and oils, and used the acid generation tank and methane By maintaining the concentration of fats and oils in the treated water introduced into an anaerobic treatment tank such as a fermenter, the selection of fat-degrading bacteria can be suppressed and the performance of fat-degrading can be maintained, and the present invention was completed.
That is, the present invention provides the following anaerobic treatment system and control method for the anaerobic treatment system.

The anaerobic treatment system of the present invention for solving the above problems is an anaerobic treatment system for anaerobicly treating oil-containing wastewater, comprising an acid production tank, a methane fermentation tank, and an oil-water separation tank for separating oil in the oil-containing wastewater. , and an adjustment function for adjusting the degree of oil separation in the oil-water separation tank.
According to the anaerobic treatment system of the present invention, an oil-water separation tank for separating fats and oils in wastewater containing fats and oils is provided, and the treated water in which the degree of separation of fats and oils is adjusted is introduced into an anaerobic treatment tank such as an acid production tank or a methane fermentation tank. By doing so, it is possible to maintain the oil concentration in the treated water for anaerobic treatment, suppress selection of oil-degrading bacteria in the anaerobic treatment tank, and stably maintain the oil-degrading performance.

Further, as one embodiment of the anaerobic treatment system of the present invention, a measurement unit for measuring the concentration of fats and oils in the treated water from which the fats and oils are separated in the oil-water separation tank, and based on the results measured by the measurement unit, the acid generation tank and methane It is characterized by having a control unit that controls the amount of treated water introduced into the fermentation tank and the degree of oil separation by the adjustment function.
According to this feature, two types of control are performed: the amount of treated water introduced into the acid generation tank and the methane fermentation tank, and the degree of separation of oil and fat, according to the oil and fat concentration of the treated water from which the oil and fat are separated in the oil-water separation tank. By doing so, it is possible to maintain the fat and oil concentration in the treated water to be subjected to anaerobic treatment, and to introduce the treated water into an anaerobic treatment tank (acidification tank or methane fermentation tank) suitable for each oil and fat concentration of the treated water. can. As a result, it is possible to maintain the fat-degrading bacteria in the anaerobic treatment tank, improve the performance of the fat-degrading bacteria, and improve the efficiency of the entire anaerobic treatment.

Further, a control method for an anaerobic treatment system of the present invention for solving the above problems is a control method for an anaerobic treatment system that anaerobicly treats oil-containing wastewater, including an oil-water separation step of separating the oil-containing wastewater into oil and treated water. , an oil-water separation adjustment step for adjusting the degree of separation of fats and oils separated in the oil-water separation step, and an anaerobic treatment step for acid production treatment and methane fermentation treatment of the treated water.
According to the method for controlling an anaerobic treatment system of the present invention, fats and oils are separated from wastewater containing fats and oils, and anaerobic treatment such as acid generation and methane fermentation is performed on the treated water in which the degree of separation of fats and oils is adjusted. By maintaining the concentration of fats and oils in the treated water to be treated, selection of fat-degrading bacteria can be suppressed, and the fat-degrading performance can be stably maintained.

Further, as one embodiment of the control method of the anaerobic treatment system of the present invention, it comprises a fat concentration measuring step of measuring the fat concentration in the treated water, and a control step based on the fat concentration measured in the fat concentration measuring step. The objects to be controlled in the step are characterized in that they are the amount of treated water introduced into the acid production process and the methane fermentation process, and the degree of separation of fats and oils.
According to this feature, according to the oil concentration of the treated water, anaerobic treatment is performed by controlling two types of control objects: the amount of treated water introduced into acid generation treatment and methane fermentation treatment, and the degree of oil separation. The oil and fat concentration in the treated water can be maintained, and the treated water can be introduced for an anaerobic treatment (acid formation treatment or methane fermentation treatment) suitable for each oil and fat concentration of the treated water. As a result, it is possible to maintain the concentration of fats and oils in the treated water for anaerobic treatment, suppress selection of fat-degrading bacteria, improve the performance of fat-decomposing bacteria by fat-degrading bacteria, and improve the efficiency of the entire anaerobic treatment. becomes possible.

According to the present invention, in anaerobic treatment of oil-containing wastewater, it is possible to suppress the decrease of oil-degrading bacteria in the anaerobic treatment tank due to fluctuations in the oil concentration of oil-containing wastewater, and to stably maintain the performance of oil-decomposing anaerobic. A method of controlling a treatment system and an anaerobic treatment system can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the anaerobic treatment system which concerns on the 1st embodiment of this invention. It is a schematic explanatory drawing of the anaerobic treatment system which concerns on the 2nd embodiment of this invention. FIG. 10 is a schematic explanatory diagram showing a process related to control of the anaerobic treatment system according to the second embodiment of the present invention; FIG. 5 is a schematic explanatory diagram showing another aspect of the process related to control of the anaerobic treatment system according to the second embodiment of the present invention; FIG. 5 is a schematic explanatory diagram showing another aspect of the process related to control of the anaerobic treatment system according to the second embodiment of the present invention; It is a schematic explanatory drawing of the anaerobic treatment system which concerns on the 3rd embodiment of this invention. It is a schematic explanatory drawing of the anaerobic treatment system which concerns on the 4th embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the anaerobic treatment system which concerns on the 4th embodiment of this invention.

INDUSTRIAL APPLICABILITY The anaerobic treatment system and the control method of the anaerobic treatment system of the present invention are suitably used in the anaerobic treatment of oil-containing wastewater.

The oil-containing wastewater to be treated refers to organic wastewater containing fats and oils in water, and includes mainly prepared food processing plant wastewater, sweets manufacturing plant wastewater, edible oil manufacturing plant wastewater, and the like. Any organic wastewater containing oil may be used, and sludge containing oil such as sewage wastewater and wastewater from livestock barns for cattle and pigs is also included.

The fats and oils contained in the wastewater are poorly soluble in water, and specific examples thereof include animal fats and oils, vegetable fats and oils, fatty acids, hydrocarbons, aromatic oils, higher alcohols, surfactants, and the like. These fats and oils may exist in a solid state as SS (Suspended Solid) in water, or may exist in a liquid state emulsified and dispersed in water or in a state separated from water.

Anaerobic treatment of oil-containing wastewater includes methane fermentation by acidogenic bacteria and methanogenic bacteria from the viewpoint of treatment cost and usefulness of generated gas.

EMBODIMENT OF THE INVENTION Hereinafter, the embodiment of the control method of the anaerobic treatment system which concerns on this invention, and an anaerobic treatment system is described in detail, referring drawings. It should be noted that the control method of the anaerobic treatment system of the present invention shall be replaced with the following description of the configuration and operation of the anaerobic treatment system. Moreover, this embodiment is merely an example for explaining the anaerobic treatment system and the control method of the anaerobic treatment system according to the present invention, and is not limited to this.

[First embodiment]
FIG. 1 is a schematic illustration of the anaerobic treatment system of the first embodiment of the present invention.
The anaerobic treatment system 1a according to this embodiment, as shown in FIG. and a methane fermentation tank 40 for performing a methane fermentation treatment on the treated water W2 that has undergone acid generation treatment. It has
In addition, a line L1 which is an introduction pipe for introducing the oil-containing waste water WO into the oil-water separation tank 10, and a line which is an introduction pipe for introducing the treated water W1 from the oil-water separation tank 10 to the acid generation tank 30 L2, a line L3 as an introduction pipe for introducing the treated water W2 from the acid generation tank 30 into the methane fermentation tank 40, and a line L3 for discharging the treated water W3 discharged from the methane fermentation tank 40 to the outside of the treatment system. It has a line L4 which is a discharge pipe.
The thick arrows in FIG. 1 indicate the flow of water.

The oil-water separation tank 10 separates the oil-containing waste water WO supplied through the line L1 into the oil O and the treated water W1.
The oil-water separation tank 10 is not particularly limited as long as it can separate the oil-containing waste water WO into the oil O and the treated water W1. For example, a grease trap that uses the difference in specific gravity between oil and water, a floc containing oil is formed by adding a flocculating agent, and pressure flotation is used to float and separate the floc with fine bubbles of pressurized water, and adsorption separation using a fat adsorbent is used. things, etc.

The oil-water separation tank 10 also has an adjustment function 20 for adjusting the degree of oil separation.
The adjustment mechanism 20 adjusts the degree of separation of the fats O and the treated water W1 in the oil-water separation tank 10, and adjusts the ratio of the fats O contained in the treated water W1. Although FIG. 1 illustrates that the adjustment mechanism 20 is provided in the vicinity of the oil O floating on the water surface of the oil-water separation tank 10, the arrangement position of the adjustment mechanism 20 is not limited to this. . For example, the adjustment mechanism 20 may be arranged on any of the ceiling, side, and bottom of the oil-water separation tank 10 , and can be appropriately selected according to the structure of the adjustment mechanism 20 .

Examples of the adjusting mechanism 20 include a mechanism for redispersing the once separated oil and fat O in the treated water W1, and a mechanism for adjusting the separation efficiency of the oil and fat O and the treated water W1.
Means for adjusting the degree of oil separation by the adjustment mechanism 20 include, for example, addition of a surfactant, ultrasonic treatment, UV irradiation, ozonation, heating, etc., as means for redispersing the once separated oil and fat O in the treated water W1. Examples include temperature, electric discharge, passage through pores, and the like. In addition, one of these adjusting means may be used, or a plurality thereof may be combined. In particular, considering the redispersion effect of fats and oils, it is preferable to combine the addition of a surfactant with other adjustment means. Another example of the adjustment mechanism 20 is to adjust the supply amount of pressurized water. This makes it possible to adjust the degree of separation of the oil O and the treated water W1 in the oil-water separation tank 10 by pressurized flotation.

The adjusting mechanism 20 is not particularly limited as long as it is for implementing the adjusting means described above. For example, an addition device for adding a surfactant, an ultrasonic treatment device, a UV irradiation device, an ozone supply device, a heating device, a discharge device, a device having fine pores and passage channels for passing oils and fats, and a supply control of pressurized water device and the like.

Further, the adjustment mechanism 20 may be any mechanism as long as it can adjust the concentration of fats and oils in the treated water W1 derived from the oil-water separation tank 10 by adjusting the degree of separation of fats and oils. It is not necessary to adjust the degree of separation. For example, a line for recovering the treated water W1 in which the oil concentration is locally increased by the adjustment mechanism 20 may be provided separately and joined to the line L2. As a result, the adjustment capability required for the adjustment mechanism 20 can be saved, and the equipment investment and running costs related to the adjustment mechanism 20 can be reduced.

The acid production tank 30 and the methane fermentation tank 40 are reaction tanks for anaerobically treating the treated water W1 introduced from the oil-water separation tank 10 . In the acid production tank 30 and the methane fermentation tank 40, the components contained in the treated water W1 are decomposed or reduced by microorganisms contained therein. The acid production tank 30 and the methane fermentation tank 40 preferably have a ceiling to form a closed space in order to maintain anaerobic conditions.

The acid-producing tank 30 decomposes solids such as sugars, proteins, and oils and macromolecular organic matter by acid-producing bacteria (mainly anaerobic acid-producing bacteria) contained therein in the treated water W1 supplied through the line L2. Then, an acid production treatment is performed to produce monosaccharides, amino acids, lower fatty acids and acetic acid. The treated water W2 treated in the acid production tank 30 is supplied to the methane fermentation tank 40 via the line L3.

The acid-producing tank 30 is provided with internal water temperature adjusting means, pH adjusting agent charging means, and means for adding metals such as nitrogen, phosphorus, cobalt and nickel, which are nutrients required by bacteria. (not shown).

The methane fermentation tank 40 performs a methane fermentation process to generate methane from monosaccharides, amino acids, lower fatty acids, acetic acid, etc. contained in the treated water W2 that is supplied through the line L3 and processed in the acid generation tank 30. Methane fermentation is performed in an anaerobic atmosphere without dissolved oxygen by methanogenic bacteria retained by the floating method, fixed bed method, fluidized bed method, UASB (Upflow Anaerobic Sludge Blanket) method, EGSB (Expanded Granular Sludge Bed) method, etc. It is something to do.

In the methane fermentation tank 40, as shown in FIG. 1, a granule layer 41 containing anaerobic bacteria suitable for anaerobic treatment is formed. Then, when the treated water W2 from the acid production tank 30 is introduced into the methane fermentation tank 40 through the line L3, the anaerobic bacteria contained in the granule layer 41 perform methane fermentation. As a result, in the methane fermentation tank 40, a gas mainly composed of methane and carbon dioxide is generated, and treated water W3 is produced. In addition, a settler 42 as a gas-solid-liquid separation means may be provided inside the methane fermentation tank 40 . The gas generated in the methane fermentation tank 40 is released or collected outside the tank (not shown). Also, the treated water W3 produced in the methane fermentation tank 40 is discharged out of the treatment system through the line L4.

In addition, the methane fermentation tank 40 can be further provided with various incidental equipment. For example, it may be provided with internal water temperature adjusting means, pH adjusting agent charging means, and means for adding metals such as nitrogen, phosphorus, cobalt and nickel, which are nutrients required by bacteria (not shown). . Moreover, it is preferable that the methane fermentation tank 40 be provided with means for collecting, purifying, and storing methane gas among the gases generated in the methane fermentation tank 40 . As a result, methane gas, which is a useful energy source, can be recovered from the oil-containing waste water WO and effectively used.

Hereinafter, anaerobic treatment of oil-containing wastewater WO by the anaerobic treatment system 1a of the present embodiment will be described.

In the anaerobic treatment system 1a of this embodiment, the oil-water separation tank 10 separates the oil-containing wastewater WO into the oil O and the treated water W1, and the treated water W1 is subjected to anaerobic treatment (acid formation treatment and methane fermentation treatment). be. As a result, it is possible to introduce the treated water W1 in which the oils and fats O that affect the anaerobic treatment have been reduced into the acid production tank 30 and the methane fermentation tank 40 . At this time, the fats O are not completely separated and removed from the treated water W1, and some of the fats O remain in the treated water W1.
This treated water W1 is introduced into the acid generation tank 30 and the methane fermentation tank 40, and the fats and oils are decomposed by the fat-decomposing bacteria. Note that the fat-degrading bacteria in the acid-producing tank 30 and the methane fermentation tank 40 may grow fat-degrading bacteria among the microorganisms accommodated in the acid-producing tank 30 and the methane fermentation tank 40. The oil-degrading bacteria may be supplied from the outside of the acid-producing tank 30 and the methane-fermenting tank 40. In addition, in the methane fermentation tank 40 using the granule layer 41, if the fats and oils O adhere to the granule layer 41, the efficiency of the methane fermentation process is significantly lowered. Therefore, it is preferable that the fats and oils O in the treated water W1 are mainly decomposed in the acid generation tank 30, and the fats and oils O to be treated in the methane fermentation tank 40 are reduced.

On the other hand, if the oil and fat concentration in the treated water W1 supplied from the oil-water separation tank 10 is maintained at a low concentration, bacteria that decompose other components in the treated water W1 preferentially proliferate, resulting in an acid generation tank. The oil-degrading bacteria housed inside 30 are eliminated and reduced. It is known that the growth rate of fat-degrading bacteria is slow, and once the fat-degrading bacteria are eliminated, it takes time to recover the efficiency of fat-degrading in the acid-producing tank 30 .

Therefore, the adjustment mechanism 20 provided in the oil-water separation tank 10 temporarily increases the concentration of fats and oils in the treated water W<b>1 and introduces the treated water W<b>1 into the acid generation tank 30 . That is, the oil-water separation tank 10 and the adjustment mechanism 20 in the anaerobic treatment system 1a of the present embodiment separate and treat the oil O in the oil-containing wastewater WO, and adjust the oil concentration of the treated water W1 to the oil decomposition in the acid generation tank 30. It functions to create a state suitable for maintaining bacteria and introduce it into the acid generation tank 30 . As a result, a certain amount of fat, which is a nutrient source (energy source and carbon source) for the fat-degrading bacteria housed in the acid generation tank 30, can be secured, suppressing the decrease of fat-degrading bacteria, It becomes possible to perform stable fats and oils decomposition.
Moreover, a part of the fats and oils O separated and treated in the oil-water separation tank 10 of the present embodiment is used for adjusting the fat and oil concentration in the treated water W1. Therefore, it is possible to reduce the amount of fats O recovered from the oil-water separation tank 10 and disposed of outside the treatment system.

As described above, by providing an oil-water separation tank and an adjustment mechanism for separating fats and oils in the fat-containing wastewater, and introducing the treated water after adjusting the degree of separation of fats and oils into an anaerobic treatment tank such as an acidification tank or a methane fermentation tank, It is possible to maintain the oil concentration in the treated water for anaerobic treatment, suppress the selection of oil-degrading bacteria in the anaerobic treatment tank, and stably maintain the oil-degrading performance.

In addition, in the anaerobic treatment system of this embodiment, part of the fats and oils separated in the oil-water separation tank is used to adjust the fat and oil concentration of the treated water, so the amount of fat and oil to be collected and disposed of is reduced, and the anaerobic treatment system is running. It also has the effect of reducing costs.

[Second embodiment]
FIG. 2 is a schematic illustration of the anaerobic treatment system 1b of the second embodiment of the present invention.
The anaerobic treatment system 1b according to this embodiment, as shown in FIG. and a control unit 60 for controlling the amount of treated water W1 introduced into the acid generation tank 30 and the methane fermentation tank 40 and the degree of oil separation by the adjustment mechanism 20 based on the results measured by the measurement unit 50 . In addition, the line L2 is branched to have a line L5 as an introduction pipe for directly introducing the treated water W1 from the oil-water separation tank 10 to the methane fermentation tank 40, and a flow path for switching between the line L2 and the line L5. It has a switching unit 61 .
In addition, the dashed-dotted line arrows in FIG. 2 indicate that they are connected so as to be controllable. Further, of the configuration of the anaerobic treatment system 1b in this embodiment, the description of the same configuration as that of the anaerobic treatment system 1a of the first embodiment will be omitted.

The measurement unit 50 is for measuring the concentration of fats and oils in the treated water W1 drawn out from the oil-water separation tank 10 . Moreover, the measurement part 50 is provided on the oil-water separation tank 10 or the line L2.
The measurement unit 50 is not particularly limited as long as it can measure the concentration of fats and oils in the treated water W1. As the measurement unit 50, for example, the treated water W1 in the oil-water separation tank 10 or the line L2 is sampled and measured through a known operation (extraction, etc.) related to the measurement of the oil-and-fat concentration, or the oil-water separation tank 10 or the line For example, L2 is provided with an oil concentration meter and directly measured.

The control unit 60 controls the amount of the treated water W1 introduced into the acid generation tank 30 and the methane fermentation tank 40 and the degree of oil separation by the adjustment mechanism 20 based on the results measured by the measurement unit 50 .

Here, to control the amount of treated water W1 introduced into the acid production tank 30 and the methane fermentation tank 40, for example, the line L2 for introducing the treated water W1 from the oil-water separation tank 10 to the acid production tank 30 is branched, and the methane For example, a line L5 for directly introducing the treated water W1 into the fermentation tank 40 is provided, and a channel switching unit 61 for switching between the line L2 and the line L5 is used. The flow path switching unit 61 may completely switch between the line L2 and the line L5, or may be capable of varying the flow rate ratio of the treated water W1 flowing through the line L2 and the line L5. Although FIG. 2 shows that the line L3 is introduced above the line L5 with respect to the methane fermentation tank 40, it is not limited to this. For example, the line L5 and the line L3 may be provided adjacent to the methane fermentation tank 40, and the like.

The control unit 60 is connected so as to be able to control the adjustment mechanism 20 and the flow path switching unit 61, as shown in FIG.
An example of control by the control unit 60 will be described below.

3 to 5 are schematic explanatory diagrams showing processes related to control in the anaerobic treatment system 1b of this embodiment. In FIGS. 3 to 5, the flow of treated water is indicated by bold arrows. 3 to 5, the configuration of the anaerobic treatment system 1b is the same as that of FIG. 2, and the description thereof is omitted. In addition, in FIGS. 3 to 5, locations where control is being performed are indicated by dashed-dotted line arrows.

When the fat concentration in the treated water W1 is equal to or higher than the predetermined value as a result of measurement by the measurement unit 50, the treated water W1 is introduced into the acid generation tank 30 and then processed in the methane fermentation tank 40 as shown in FIG. Water W2 is introduced and the process proceeds.
On the other hand, when the fat concentration in the treated water W1 is less than the predetermined value as a result of measurement by the measurement unit 50, the control unit 60 causes the adjustment mechanism 20 to separate the fats and oils in the oil-water separation tank 10 as shown in FIG. The degree is adjusted, and control is performed so that the concentration of fats and oils in the treated water W1 is increased to a certain extent.
Thereby, the adjustment mechanism 20 can be operated as needed, and the running cost of the anaerobic treatment system can be reduced.

In addition, when the concentration of fats and oils in the fat-containing wastewater WO continues to decrease for a long period of time, the amount of fats O separated in the oil-water separation tank 10 is also reduced. Even if the degree of oil separation is adjusted, the oil concentration in the treated water W1 cannot be increased. At this time, if the treated water W1 having a low fat concentration is introduced into the acid generator 30, there is a possibility that the fat-decomposing bacteria in the acid generator 30 will be eliminated.
Therefore, when the fat concentration in the treated water W1 measured by the measuring unit 50 is less than a predetermined value for a certain period of time, as shown in FIG. It is controlled so as to be introduced directly into the methane fermentation tank 40 . As a result, it is possible to suppress the reduction of fat-degrading bacteria housed in the acid-producing tank 30 and stably maintain the fat-degrading performance.

Further, as another example of control by the control unit 60, when the concentration of fats and oils in the treated water W1 measured by the measurement unit 50 is less than a predetermined value, the adjustment mechanism 20 adjusts the degree of separation of fats and oils, and the flow path is switched. For example, the flow rate ratio of the treated water W1 introduced into the line L2 and the line L5 is changed by the unit 61 . In this case, by directly introducing a portion of the treated water W1 into the methane fermentation tank 40 while the oil concentration in the treated water W1 is being adjusted, the treated water W1 with the low oil concentration introduced into the acid generation tank 30 decreases the amount of As a result, it is possible to suppress the weeding out of fat-decomposing bacteria in the acid generator tank 30 while the acid generator treatment in the acid generator tank 30 is continued.

The predetermined value of the oil concentration measured by the measurement unit 50, which is the reference for the control by the control unit 60, is determined by taking into consideration the properties of the oil-containing wastewater WO, the structure and processing capacity of the acid generation tank 30 and the methane fermentation tank 40. It can be set and is not particularly limited. For example, the predetermined value may be set to 30 mg/L of normal-hexane extraction substance amount. Thereby, it is possible to secure a nutrient source necessary for the growth of fat-degrading bacteria in the acid-producing tank 30 .

As described above, according to the anaerobic treatment system 1b of the present embodiment, the amount of treated water introduced into the acid production tank and the methane fermentation tank and the amount of oil and fat in accordance with the oil and fat concentration of the treated water from which the oil and fat are separated in the oil and water separation tank. By performing two types of control, the degree of separation, the oil concentration in the treated water for anaerobic treatment can be maintained, and the treatment tank (acidification tank or methane fermentation tank) suitable for each oil concentration in the treated water Treated water can be introduced into As a result, it is possible to maintain the fat-degrading bacteria in the anaerobic treatment tank, improve the performance of the fat-degrading bacteria, and improve the efficiency of the entire anaerobic treatment. In particular, even when the concentration of fats and oils in the fat-containing wastewater decreases for a long period of time, it is possible to maintain the fat-degrading bacteria in the anaerobic treatment tank.

[Third embodiment]
FIG. 6 is a schematic illustration of the anaerobic treatment system 1c of the third embodiment of the present invention.
As shown in FIG. 6, the anaerobic treatment system 1c according to this embodiment is the anaerobic treatment system 1a of the first embodiment, in which a plurality of layers with different concentrations of fats and oils are formed in the oil-water separation tank 10, and In addition to the line L2 and line L3 for introducing the treated water W11 to the acid production tank 30 and the methane fermentation tank 40, there is a line L6 for introducing the treated water W12 having a low fat concentration to the methane fermentation tank 40.
In addition, in the configuration of the anaerobic treatment system 1c in this embodiment, the description of the same configuration as that of the anaerobic treatment system 1a of the first embodiment will be omitted.

The oil-water separation tank 10 of this embodiment forms a plurality of layers having different concentrations of fats and oils in the oil-water separation tank 10 by means of the adjustment mechanism 20 . As the adjustment mechanism 20 at this time, for example, a mechanism that uses pressurized floatation and adjusts the supply amount of pressurized water to form a plurality of layers with different concentrations of fats and oils in the oil-water separation tank 10 can be mentioned. In addition, in FIG. 6, although the oil concentration of the upper part side of the oil-water separation tank 10 is shown, it is not limited to this. In addition, the layers with different fat and oil concentrations in the oil-water separation tank 10 may be clearly distinguished as shown in FIG. good.

As shown in FIG. 6, in the anaerobic treatment system 1c of the present embodiment, as the treated water W1 from the oil-water separation tank 10, the treated water W11 from the layer with high fat and oil concentration is introduced into the acid generation tank 30 through the line L2. On the other hand, the treated water W12 from the layer with low fat and oil concentration is introduced into the methane fermentation tank 40 via the line L6. As a result, the treated water W11 introduced into the acid-producing tank 30 can be kept in a state where the oil concentration is maintained at a certain level, and the selection of the oil-degrading bacteria contained in the acid-producing tank 30 can be suppressed. On the other hand, by directly introducing the treated water W12 having a low fat and oil concentration into the methane fermentation tank 40, it is possible to decompose fat and oil without interfering with the methane fermentation process. Although FIG. 6 shows that the line L3 is introduced above the line L6 with respect to the methane fermentation tank 40, it is not limited to this. For example, the line L6 and the line L3 may be provided adjacent to the methane fermentation tank 40, and the like.

With the anaerobic treatment system 1c of the present embodiment, treated water according to each anaerobic treatment tank (acid production tank 30 and methane fermentation tank 40) without measuring the oil and fat concentration of the treated water derived from the oil-water separation tank 10 (treated water W11 and W12) can be introduced.

[Fourth embodiment]
FIG. 7 is a schematic illustration of an anaerobic treatment system 1d according to the fourth embodiment of the present invention.
As shown in FIG. 7, the anaerobic treatment system 1d according to the present embodiment recovers the fats and oils O separated in the oil-water separation tank 10 in the anaerobic treatment system 1a of the first embodiment, and saponifies them under alkaline conditions. It is provided with an alkali tank 70 for carrying out. In addition, an alkaline solution after saponification treatment (hereinafter simply referred to as "solution SO") is introduced into the acid generation tank 30 from the line L7 for recovering fats and oils O from the oil-water separation tank 10 and introducing them into the alkali tank 70, and from the alkali tank 70. It has a line L8 to
The alkali tank 70 of this embodiment, as shown in FIG. 7, may replace the adjustment mechanism 20 provided in the oil-water separation tank 10 in the first embodiment. It may be used in combination.
It should be noted that, of the configuration of the anaerobic treatment system 1d of this embodiment, the description of the same configuration as that of the anaerobic treatment system 1a of the first embodiment will be omitted.

The alkali tank 70 of this embodiment recovers the oil O from the oil-water separation tank 10 through the line L7, saponifies the oil O under alkaline conditions, and stores the solution SO. At this time, the solution SO mainly contains glycerin and higher fatty acids, and the proteins causing putrefaction are hydrolyzed and various bacteria are lysed. Therefore, the solution SO can be suitably used as a nutrient source for fat-decomposing bacteria in the acid-producing tank 30 .
The solution SO in the alkali tank 70 is supplied to the acid generator tank 30 through the line L8. As a result, the concentration of fats and oils (in this case, the concentration of free fatty acids such as glycerin and higher fatty acids) in the acid generation tank 30 can be maintained at a certain level, and the fats and oils contained in the acid generation tank 30 can be decomposed. It can suppress selection of bacteria.
Further, since the solution SO is alkaline, it can also be used as a pH adjuster against the pH drop in the acid generation tank 30 accompanying the progress of the reaction in the acid generation tank 30 .

FIG. 8 is a schematic explanatory diagram showing another aspect of the anaerobic treatment system 1d of this embodiment. In addition, in FIG. 8, description of the same configuration as that of the anaerobic treatment system 1b of the second embodiment will be omitted.

As shown in FIG. 8, in the anaerobic treatment system 1d of the present embodiment, the measurement unit 50 in the second embodiment and the measurement result of the measurement unit 50 determine the concentration of the solution SO introduced from the alkali tank 70 into the acid generation tank 30. A controller 80 for controlling the amount of supply may be provided. The means for controlling the supply amount of the solution SO introduced from the alkali tank 70 to the acid generation tank 30 is not particularly limited. For example, as shown in FIG. 8, control of a flow control mechanism 90 such as a valve provided on line L8 can be mentioned. As a result, the concentration of fats and oils in the acid generation tank 30 can be maintained so as to be in a state suitable for maintaining the fat-degrading bacteria in the anaerobic treatment tank and improving the performance of fat-decomposing the fats and oils by the fat-degrading bacteria. It is possible to improve the efficiency of the entire process.

Further, as shown in FIG. 8, the anaerobic treatment system 1d of the present embodiment may be provided with the flow path switching section 61 of the second embodiment and controlled by the control section 80. FIG. For example, the concentration of fats and oils in the treated water W1 measured by the measurement unit 50 is less than a predetermined value for a certain period of time, and the concentration of fats and oils in the fat-containing wastewater WO continues to decrease for a long period of time. When the amount of fats and oils O in the methane fermentation tank 40 is reduced, the control unit 80 switches the flow path switching unit 61 so that the treated water W1 is introduced directly into the methane fermentation tank 40 . As a result, it is possible to suppress the reduction of fat-degrading bacteria housed in the acid-producing tank 30 and stably maintain the fat-degrading performance.

With the anaerobic treatment system 1d of the present embodiment, the oils and fats O separated in the oil-water separation tank 10 are saponified, and the solution SO after the saponification treatment is introduced into the acid generation tank 30 to perform anaerobic treatment. It is possible to maintain the oil concentration and suppress selection of oil-degrading bacteria in the anaerobic treatment tank, thereby stably maintaining the oil-degrading performance. In addition, by using the separated fat O as the solution SO, it is possible to reduce the cost of fat treatment.

In addition, the embodiment mentioned above shows an example of the control method of an anaerobic treatment system and an anaerobic treatment system. The anaerobic treatment system and the anaerobic treatment system control method according to the present invention are not limited to the above-described embodiments, and the anaerobic treatment system and the anaerobic treatment system according to the above-described embodiments are not limited to the scope of the claims. The control method of the processing system may be modified.

For example, in the anaerobic treatment system of this embodiment, a return line may be provided that branches from the line L2 and returns the treated water W1 to the oil-water separation tank. Further, when the oil concentration measured by the measurement unit indicates a range exceeding the oil decomposition in the acid generator tank, the line may be switched to the return line. As a result, when the concentration of fats and oils in the treated water W1 is in a range that inhibits the anaerobic treatment in the acid production tank and the methane fermentation tank, it is possible to separate the fats and oils again in the oil-water separation tank.
Further, in the anaerobic treatment system of this embodiment, a return line may be provided that branches from the line L3 and returns the treated water W2 to the oil-water separation tank. At this time, a measurement unit is also provided on the line L3 to measure the concentration of fats and oils, and when the concentration of fats and oils in the treated water W2 from the acid generation tank indicates a range that inhibits the treatment in the methane fermentation tank, It is also possible to switch to a return line branched from the line L3. As a result, when the concentration of fats and oils in the treated water W2 is in a range that inhibits the anaerobic treatment in the methane fermentation tank, it is possible to separate the fats and oils again in the oil-water separation tank.

In addition, in the anaerobic treatment system of this embodiment, the acid generator and the methane fermentation tank may be equipped with those capable of promoting the growth of fat-decomposing bacteria. Examples thereof include those in which a carrier or the like capable of retaining microorganisms is added. As a result, the fat-degrading bacteria are retained in the carrier, thereby promoting the growth of the fat-degrading bacteria and maintaining the fat-degrading performance in the acid generator tank and the methane fermentation tank.

The anaerobic treatment system of the present invention is used for anaerobic treatment of waste water containing fats and oils. In particular, the anaerobic treatment system of the present invention is suitably used for anaerobic treatment in which the concentration of fats and oils in wastewater containing fats and oils fluctuates.

1a, 1b, 1c, 1d anaerobic treatment system, 10 oil-water separation tank, 20 adjustment mechanism, 30 acid production tank, 40 methane fermentation tank, 41 granule layer, 42 settler, 50 measurement unit, 60 control unit, 61 flow path switching Part, 70 Alkaline tank, 80 Control unit, 90 Flow rate adjustment mechanism, L1 to L8 line, O Fats and oils, SO solution, WO Oil and fat-containing waste water, W1 to W3, W11, W12 Treated water

Claims (4)

In the anaerobic treatment system that anaerobicly treats oil-containing wastewater,
an acid generator;
a methane fermentation tank;
an oil-water separation tank for separating oil and fat in the oil-containing wastewater;
With an adjustment function for adjusting the degree of oil separation in the oil-water separation tank,
The oil-water separation tank is provided upstream of the acid production tank and the methane fermentation tank,
The adjustment function is to redisperse the fats and oils separated in the oil-water separation tank in the fat-containing wastewater, and adjust the degree of separation of the fats and oils so that the fat-decomposing performance in the acid-producing tank or the methane fermentation tank can be maintained. An anaerobic treatment system characterized by: a measuring unit for measuring the concentration of fats and oils in treated water from which fats and oils are separated in the oil-water separation tank;
A control unit for controlling the amount of treated water introduced into the acid production tank and the methane fermentation tank and the degree of oil separation by the adjustment function based on the results measured by the measurement unit. 1. The anaerobic treatment system according to 1 . In a control method for an anaerobic treatment system that anaerobicly treats oil-containing wastewater,
an oil-water separation step for separating oil-containing waste water into oil and treated water;
An oil-water separation adjustment step for adjusting the degree of separation of the oil and fat separated in the oil-water separation step;
An anaerobic treatment step of acid production treatment and methane fermentation treatment of the treated water,
The oil-water separation and adjustment step re-disperses the fats and oils separated in the oil-water separation step in the fat-containing wastewater, and adjusts the degree of separation of fats and oils so that the fat-decomposing performance in the anaerobic treatment step can be maintained. , the control method of the anaerobic treatment system. A fat concentration measuring step of measuring the fat concentration in the treated water;
Claim 3 , characterized by comprising a control step of controlling the amount of treated water introduced into the acid generation process and the methane fermentation process and the degree of separation of fats and oils based on the fat and oil concentration measured in the fat and oil concentration measuring step. Control method of the anaerobic treatment system according to.

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