JP2020157278A - Anaerobic treatment apparatus and anaerobic treatment method - Google Patents

Abstract

To provide an anaerobic treatment apparatus and an anaerobic treatment method that make it possible to grasp with high accuracy changes in pH during anaerobic treatment of treated water from acid production treatment, so as to suppress decrease in efficiency of the anaerobic treatment.SOLUTION: An anaerobic treatment apparatus comprising a reaction unit that anaerobically treats wastewater having passed through an acid generation tank; a pH measuring unit that measures the pH in the reaction unit; and a pH adjustment unit that performs pH adjustment treatment to the wastewater in the reaction unit, based on the pH value measured in the reaction unit, to adjust the pH of the wastewater in the reaction unit. The changes of pH in the reaction unit can be grasped with high accuracy by measuring pH of the wastewater in the reaction unit, and by performing pH adjustment treatment to the wastewater in the reaction unit, it is possible to maintain an appropriate range of pH for anaerobic treatment in the reaction unit, thereby suppressing reduction in the efficiency of the anaerobic treatment.SELECTED DRAWING: Figure 1

Description

The present invention relates to an anaerobic treatment apparatus and an anaerobic treatment method.

In general, biological treatment using various microorganisms is known as a method for treating wastewater containing organic substances. In particular, biological treatment in an anaerobic environment (hereinafter referred to as "anaerobic treatment") does not require aeration power and hardly generates excess sludge, and has high merits related to introduction.

As such an anaerobic treatment, a methane fermentation treatment is known. Methane fermentation treatment is an anaerobic treatment that decomposes organic matter in wastewater into methane and carbon dioxide by the action of anaerobic microorganisms in an anaerobic environment, and is an anaerobic treatment from the viewpoint of treatment cost and usefulness of produced gas. Widely used.

The methane fermentation treatment includes an acid production step in which acid-producing bacteria are brought into contact with organic matter in wastewater to generate acid, and a methane-producing step in which methanogens are brought into contact with a treatment liquid produced by acid to produce methane. Is done. Since the acid production step and the methane production step have different suitable progress conditions, they are usually carried out in separate treatment tanks (acid generation tank and methane fermentation tank).

For example, Patent Document 1 describes an anaerobic treatment apparatus provided with an acid generation tank and a methane fermentation tank as anaerobic treatment of wastewater containing organic substances. Further, Patent Document 1 describes a process of returning by a return step in an anaerobic treatment method including an acid production step, a methane production step, and a return step of returning a part of the treatment liquid of the methane production step to the acid generation step. It is described that by specifying the amount of liquid, it is possible to suppress a decrease in pH in the acid production step and reduce the amount of alkali added.

Japanese Unexamined Patent Publication No. 9-1178

Generally, in the anaerobic treatment by the acid production step and the methane fermentation step, there is a suitable pH range for each step.
In the acid production step, an organic acid is produced, so that the pH in the acid generation tank is lowered. At this time, the activity of the acid-producing bacteria may be inhibited by the decrease in pH.
Here, as described in Patent Document 1, it is already known that pH measurement and pH adjustment are performed in an acid-producing tank in order to maintain high activity of acid-producing bacteria. Further, as described in Patent Document 1, a method for reducing the amount of alkali added to the acid generation tank is also being studied.

On the other hand, Patent Document 1 does not describe that pH measurement and pH adjustment in a methane fermentation tank are performed. In the anaerobic treatment apparatus described in Patent Document 1, a treatment liquid whose pH is measured and adjusted in an acid generation tank provided in front of the methane fermentation tank is supplied to the methane fermentation tank. Therefore, it is considered that the pH value of the supplied treatment liquid is maintained even in the methane fermentation tank, and it is presumed that the pH measurement and pH adjustment in the methane fermentation tank are not positively performed.

However, the pH in the methane fermenter where the methane production step is performed is not always kept constant. Therefore, there is a problem that the pH fluctuation in the methane fermentation tank cannot be grasped only by measuring the pH and adjusting the pH in the acid generation tank, which leads to a decrease in anaerobic treatment efficiency.

An object of the present invention is to provide an anaerobic treatment apparatus and an anaerobic treatment method capable of grasping the fluctuation of pH at the time of anaerobic treatment of treated water after acid production treatment with high accuracy and suppressing a decrease in anaerobic treatment efficiency. That is.

As a result of diligent studies on the above problems, the present inventor reduced the anaerobic treatment efficiency by measuring the pH of the wastewater in the reaction section for anaerobically treating the treated water after the acid production treatment and adjusting the pH in the anaerobic treatment. The present invention has been completed by finding that it can be suppressed.
That is, the present invention is the following anaerobic treatment apparatus and anaerobic treatment method.

The anaerobic treatment apparatus of the present invention for solving the above problems has a reaction unit for anaerobic treatment of wastewater passing through an acid generation tank, a pH measurement unit for measuring the pH of the reaction unit, and a pH measurement unit for measuring pH. It is characterized by including a pH adjusting unit that adjusts the pH of the wastewater in the reaction unit by performing a pH adjusting treatment on the wastewater in the reaction unit based on the value.
The anaerobic treatment apparatus of the present invention can grasp the pH fluctuation in the reaction part with high accuracy by measuring the pH of the wastewater in the reaction part, and directly adjusts the pH of the wastewater in the reaction part. Therefore, it is possible to maintain a pH range suitable for anaerobic treatment in the reaction section. This makes it possible to suppress a decrease in anaerobic treatment efficiency.

Further, as one embodiment of the anaerobic treatment apparatus of the present invention, the reaction section is provided with a circulation section for circulating wastewater in the reaction section, and the circulation section is provided with a pH measuring section and a pH adjusting section.
According to this feature, since the effect of stirring the wastewater in the reaction part can be obtained, the wastewater in the reaction part can be homogenized and the pH in the reaction part can be grasped with higher accuracy. In addition, the stirring effect of the circulating portion improves the contact efficiency between the components in the wastewater and the anaerobic microorganisms in the reaction portion, and makes it possible to increase the anaerobic treatment efficiency.

Further, as the anaerobic treatment apparatus of the present invention for solving the above-mentioned problems, a reaction unit that anaerobically treats wastewater that has passed through an acid generation tank, a pH measurement unit that measures the pH of the reaction unit, and a pH measurement unit measure the pH. It is characterized by including a pH adjusting unit that adjusts the pH of wastewater in the reaction unit based on the pH value.
The anaerobic treatment apparatus of the present invention can grasp the pH fluctuation in the reaction part with high accuracy by measuring the pH of the wastewater in the reaction part, and can perform the pH adjustment treatment on the wastewater in the reaction part. , It becomes possible to maintain a pH range suitable for anaerobic treatment in the reaction part. This makes it possible to suppress a decrease in anaerobic treatment efficiency.

Further, in one embodiment of the anaerobic treatment apparatus of the present invention, the pH adjusting unit performs a pH adjusting treatment on the wastewater in the acid generation tank based on the pH value measured by the pH measuring unit, and in the reaction unit. It has the feature of adjusting the pH of wastewater.
According to this feature, by performing the pH adjusting treatment of the wastewater in the acid generation tank according to the pH of the reaction part, it is possible to indirectly perform the pH adjusting treatment on the wastewater in the reaction part. As a result, the pH of the acid generation tank and the reaction unit can be adjusted by one pH adjusting unit, and the pH range can be controlled to be suitable for each treatment step.

Further, as the anaerobic treatment method of the present invention for solving the above-mentioned problems, a reaction step of anaerobically treating the wastewater passing through the acid generation tank in the reaction section, a pH measurement step of measuring the pH of the reaction section, and pH measurement It is characterized by including a pH adjusting step for adjusting the pH of wastewater in the reaction section based on the pH value measured in the step.
In the anaerobic treatment method of the present invention, by measuring the pH of waste water in the reaction part, the pH fluctuation in the reaction part can be grasped with high accuracy, and the pH of the wastewater in the reaction part is adjusted directly or indirectly. By performing the treatment, it is possible to maintain a pH range suitable for the anaerobic treatment in the reaction part. This makes it possible to suppress a decrease in anaerobic treatment efficiency.

According to the present invention, there is provided an anaerobic treatment apparatus and an anaerobic treatment method capable of grasping the fluctuation of pH at the time of anaerobic treatment of treated water after acid production treatment with high accuracy and suppressing a decrease in anaerobic treatment efficiency. be able to.

It is the schematic explanatory drawing of the anaerobic treatment apparatus in the 1st Embodiment of this invention. It is the schematic explanatory drawing of the anaerobic treatment apparatus in the 2nd Embodiment of this invention. It is the schematic explanatory drawing of the anaerobic treatment apparatus in the 3rd Embodiment of this invention.

The anaerobic treatment apparatus and the anaerobic treatment method of the present invention are suitably used in the anaerobic treatment of wastewater.

The wastewater to be treated in the present invention includes industrial wastewater discharged from various factories such as food factories and chemical factories. Further, from the viewpoint of more exerting the effect of the present invention, the wastewater to be treated of the present invention is preferably wastewater containing a lower alcohol or an organic acid, and particularly wastewater containing a high concentration of a lower alcohol or an organic acid. Is more preferable. The lower alcohol preferably has 6 or less carbon atoms, and particularly preferably has 3 or less carbon atoms. Examples of such wastewater include kraft pulp wastewater generated during pulp production, factory wastewater related to the production of electronic parts such as semiconductors, and factory wastewater related to resin production. The wastewater to be treated according to the present invention is not limited to this, and any wastewater containing an organic substance that can be biologically treated under anaerobic conditions is the subject of the treatment of the present invention.

Hereinafter, embodiments of the anaerobic treatment apparatus and the anaerobic treatment method according to the present invention will be described in detail with reference to the drawings. The anaerobic treatment device described in the embodiment is merely exemplified for the purpose of explaining the anaerobic treatment device according to the present invention, and is not limited thereto. Further, the anaerobic treatment method described in the present embodiment is merely exemplified for explaining the anaerobic treatment method using the anaerobic treatment device according to the present invention, and is not limited thereto.

[First Embodiment]
FIG. 1 is a schematic explanatory view of an anaerobic treatment device according to the first embodiment of the present invention.
As shown in FIG. 1, the anaerobic treatment apparatus 1a according to the present invention includes an acid generation tank 2 for introducing wastewater WO from various factories and a reaction unit 3 for anaerobic treatment of water W1 to be treated from the acid generation tank 2. A pH measuring unit 4 for measuring the pH of the reaction unit 3 and a pH adjusting unit 5 for adjusting the pH of the water to be treated W1 in the reaction unit 3 are provided. Further, a line L1 which is an introduction pipe for introducing the waste water WO into the acid generation tank 2, a line L2 which introduces the water to be treated W1 discharged from the acid generation tank 2 into the reaction unit 3, and the reaction unit 3 It has a line L3 which is a discharge pipe for discharging the treated water W discharged from the system to the outside of the system. The thick arrow in FIG. 1 indicates the flow of water, and the dashed arrow at one point indicates that the connection is controllable.

The acid generation tank 2 is for performing an acid production step of decomposing organic substances in wastewater WO by acid-producing bacteria, which are absolutely anaerobic bacteria, to generate organic acids in an anaerobic atmosphere without dissolved oxygen. .. As shown in FIG. 1, the drainage WO is supplied to the acid generation tank 2 via the line L1 provided in the lower part of the acid generation tank 2. In the acid-producing tank 2, the components contained in the wastewater WO are decomposed by the acid-producing bacteria contained therein. The water W1 to be treated after the acid generation treatment is discharged from the acid generation tank 2 via the line L2 provided in the upper part of the acid generation tank 2. It is essential that the acid generation tank 2 is a closed system and maintains an anaerobic environment.

As the acid-producing bacteria housed in the acid-producing tank 2, the cells contained in the treated water W circulated to the acid-producing tank 2 by the line L4 are used. When methane fermentation is performed only by a reaction that does not go through acid production, it is not necessary to replenish the line L4 and other acid generation tanks with bacteria.

The acid generation tank 2 in the present embodiment may be further provided with various incidental facilities. For example, the acid generation tank 2 may be provided with an internal water temperature adjusting means and a means for adding metals such as nitrogen, phosphorus, cobalt and nickel which are nutrient sources required by the acid producing bacteria. Further, in the acid generation tank 2, a carrier holding an acid-producing bacterium may be used.

The reaction unit 3 is for performing a reaction step of anaerobically treating the water to be treated W1 treated in the acid generation tank 2. As shown in FIG. 1, the reaction unit 3 includes a methane fermentation tank 31 and a separation device 32 for separating methane gas, treated water W, and solids in the upper part of the methane fermentation tank 31.

The methane fermentation tank 31 is for performing a methane fermentation step of producing methane from a carbon source contained in the water to be treated W1 treated in the acid generation tank 2. The methane fermentation step is carried out in an anaerobic atmosphere without dissolved oxygen by methanogens held in the methane fermentation tank 31 by a floating bed method, a fixed bed method, a fluidized bed method, a UASB method, an EGSB method or the like. It is essential that the methane fermentation tank 31 be a closed system and maintain an anaerobic environment.

The methanogen retained in the methane fermenter 31 is not particularly limited. For example, an isolated microorganism may be used, or seed sludge from another anaerobic treatment facility or the like may be used. Further, the anaerobic microorganisms contained in the wastewater WO may be utilized.

The form of the methanogen is not particularly limited, and examples thereof include the use of granules of microorganisms having a diameter of about 0.3 to 3 mm called granules. Granules are microbial masses that utilize self-immobilization and are capable of maintaining high cell concentrations. Therefore, by using granules, a layer in which the methanogen is maintained at a high concentration is formed in the methane fermentation tank 31.
Further, in the methane fermentation tank 31, a carrier holding a methanogen may be used.
Hereinafter, a layer made of methanogens, such as a granule layer and a carrier layer holding methanogens, is referred to as an anaerobic microbial layer M.

It is preferable to provide means for recovering or reusing the methane gas, the treated water W and the solid content separated by the separation device 32. For example, methane gas is preferably provided with means for recovering, purifying and storing it in order to use it as biogas. In addition to being discharged to the outside of the system via the line L3, the treated water W is partially used as circulating water WR and returned to the acid generation tank 2 via the line L4 branched from the line L3 to generate acid. It may be used for adjusting the pH or diluting the waste water WO in the tank 2. Further, since the solid content contains methanogens, it is preferable to hold it in the methane fermentation tank 31 using a separation device 32 so that it does not flow out of the system. Further, a part of the solid component may be supplied to the acid producing tank 2 and used as seed sludge for acid producing bacteria.

The reaction unit 3 in the present embodiment may be further provided with various incidental equipment. For example, the reaction unit 3 may be provided with an internal water temperature adjusting means and a means for adding metals such as nitrogen, phosphorus, cobalt and nickel which are nutrient sources required by methanogens.

The pH measuring unit 4 performs a pH measuring step of measuring the pH of the reaction unit 3, and more specifically, measuring the pH of the water to be treated W1 in the methane fermentation tank 31 can be mentioned.
The pH measuring unit 4 is not particularly limited as long as it can measure the pH of the water to be treated W1, and a known pH meter can be used. Further, in order to grasp the pH fluctuation of the water to be treated W1 in the methane fermentation tank 31 with high accuracy, the pH measuring unit 4 continuously measures the pH while the water to be treated W1 is present in the methane fermentation tank 31. It is preferable to perform this and monitor the information related to the fluctuation of pH.

The location where the pH measuring unit 4 is provided is not particularly limited. For example, the pH measuring unit 4 may be provided so that the water W1 to be treated in the methane fermentation tank 31 can be directly measured, and the pH can be measured with respect to the water W1 to be treated extracted from the methane fermentation tank 31. The pH measuring unit 4 may be provided as described above.
Further, as will be described later, a plurality of pH measuring units 4 may be provided.

In the methane fermentation tank 31 forming the anaerobic microbial layer M, the pH may fluctuate locally depending on the active state of the methanogen. Therefore, in order to grasp the pH in the reaction unit 3 with high accuracy, it is preferable to measure the pH in a state where the water to be treated W1 in the reaction unit 3 is homogenized.

As the homogenizing means in the reaction unit 3, stirring in the methane fermentation tank 31 can be mentioned.
Specifically, for example, as shown in FIG. 1, a circulation unit 6 for circulating the water to be treated W1 in the reaction unit 3 is provided, and a pH measurement unit 4 is provided on the circulation unit 6.
The circulation unit 6 includes a return line 61 and a pump 62 for extracting a part of the water to be treated W1 in the methane fermentation tank 31 and returning it to the line L2 side. Since the circulation unit 6 circulates the water to be treated W1 in the methane fermentation tank 31 by the pump 62, it becomes easy to form a water flow having a stirring effect in the methane fermentation tank 31. As a result, the inside of the methane fermentation tank 31 can be agitated to homogenize the water to be treated W1, and the accuracy of pH measurement in the pH measuring unit 4 can be improved.
Further, since the inside of the methane fermentation tank 31 is agitated by the circulation unit 6, the contact efficiency between the water to be treated W1 and the anaerobic microbial layer M is improved, and the methane fermentation process can be promoted.

Further, the position where the water to be treated W1 is extracted by the circulation unit 6 is preferably the upper part of the anaerobic microbial layer M housed in the methane fermentation tank 31. As a result, solid matter such as methanogens in the methane fermentation tank 31 can be prevented from flowing into the circulation unit 6, and the pH measurement accuracy in the pH measurement unit 4 can be improved.

The pH adjusting unit 5 performs a pH adjusting step of adjusting the pH of the water to be treated W1 in the reaction unit 3 based on the pH value measured by the pH measuring unit 4. Further, the pH adjusting unit 5 of the present embodiment directly performs the pH adjusting treatment on the water W1 to be treated in the reaction unit 3.

Further, the pH adjusting unit 5 is for setting the pH range of the water to be treated W1 in the reaction unit 3 to be suitable for anaerobic treatment (methane fermentation treatment). It is preferable that the water to be treated W1 in the reaction section 3 is near neutral. Specifically, the lower limit of pH is preferably 6.0. The upper limit of pH is preferably 7.5. This makes it possible to suppress a decrease in processing efficiency related to the methane fermentation step due to methanogens.

Examples of the pH adjusting unit 5 include a pH adjusting agent adding unit 52 to which a pH adjusting agent 51 is added in order to adjust the pH of the water to be treated W1 in the reaction unit 3.
The pH adjuster addition unit 52 includes, for example, a storage tank for storing the pH adjuster 51 and a pipe connected to the storage tank, and the pH adjuster 51 is added by an addition amount control mechanism such as a valve provided in the pipe. There are things to do. Further, as another example, an inlet is provided in the target to which the pH adjusting agent 51 is added, and a preset amount of the pH adjusting agent 51 is added.

Further, it is preferable that the pH adjusting unit 5 controls the amount of the pH adjusting agent 51 added from the pH adjusting agent adding unit 52 based on the measurement result of the pH measuring unit 4.
The control means in the pH adjusting unit 5 is not particularly limited. For example, as shown in FIG. 1, it is possible to directly input the measurement result of the pH measuring unit 4 and provide a control unit 53 for controlling the pH adjusting agent adding unit 52. At this time, the control unit 53 calculates the amount of the pH adjuster 51 added based on the measurement result of the pH measurement unit 4, and makes it possible to control the amount of the pH adjuster 51 added from the pH adjuster addition unit 52. Can be mentioned. As another control means, the operator determines the amount of the pH adjuster 51 to be added based on the measurement result of the pH measurement unit 4, and adds the pH adjuster 51 via the pH adjuster addition unit 52. And so on. In consideration of work efficiency, it is preferable to provide a control unit 53 in the pH adjusting unit 5 to automate the calculation of the amount of the pH adjusting agent 51 added and the addition of the pH adjusting agent 51.

As the pH adjuster 51, known substances are used for both acids and alkalis. For example, when the measurement result by the pH measuring unit 4 is on the acidic side (pH less than 6.0), sodium hydroxide is used as the pH adjusting agent 51, and the pH of the water to be treated W1 is set to 6.0 or more. When the measurement result by the pH measuring unit 4 is on the alkaline side (greater than pH 7.5), hydrochloric acid is used as the pH adjusting agent 51, and the pH of the water to be treated W1 is set to 8.5 or less. When the measurement result of the pH measuring unit 4 is in the range of pH 6.0 to 7.5, it is not necessary to add the pH adjusting agent 51.

The location where the pH adjuster 51 is added to the water W1 to be treated by the pH adjuster 5 is not particularly limited. For example, the pH adjusting agent 51 may be added directly into the methane fermentation tank 31, or the pH adjusting agent 51 may be added to the water to be treated W1 extracted from the methane fermentation tank 31.

For example, as shown in FIG. 1, a pH adjuster addition unit 52 is provided on the circulation unit 6 to adjust the pH of the water to be treated W1. As a result, the stirring effect in the methane fermentation tank 31 by the circulation unit 6 can be obtained, so that the pH in the reaction unit 3 can be homogenized and the methane fermentation step can be promoted.

Further, when the pH adjuster 51 is added on the circulation unit 6, the positional relationship between the installation location of the pH measurement unit 4 and the installation location of the pH adjuster addition unit 52 is not particularly limited. For example, as shown in FIG. 1, a pH adjuster addition unit 52 may be provided on the upstream side of the pH measurement unit 4. Thereby, it is possible to grasp with high accuracy whether or not the water to be treated W1 returned to the methane fermentation tank 31 satisfies a predetermined pH. Further, the pH adjuster addition unit 52 may be provided on the downstream side of the pH measurement unit 4. As a result, it becomes easy to calculate the required amount of the pH adjuster 51 added, and the amount of the pH adjuster 51 added can be set to an appropriate amount, so that the cost can be reduced.

The anaerobic treatment device 1a of the present embodiment may be provided with a plurality of pH measuring units 4.
At this time, as an example of the location where the plurality of pH measuring units 4 are provided, it can be mentioned that they are provided before and after the pH adjusting agent adding unit 52 provided on the circulation unit 6. Thereby, the amount of the pH adjusting agent 51 added can be easily calculated based on the pH of the water to be treated W1 introduced into the circulation unit 6, and the pH of the water to be treated W1 to which the pH adjusting agent 51 is added can be adjusted. It is possible to confirm whether or not it is within a predetermined range.

Further, as another example of the location where the plurality of pH measuring units 4 are provided, it can be mentioned that the pH measuring units 4 are provided in the methane fermentation tank 31 and in the circulation unit 6, respectively. At this time, the stirring efficiency in the methane fermentation tank 31 is controlled by controlling the flow rate of the water to be treated W1 introduced from the circulation unit 6 based on the measurement results of each pH measuring unit 4, and the inside of the methane fermentation tank 31. The pH of the water to be treated W1 may be homogenized.
Further, as another example of the location where the plurality of pH measuring units 4 are provided, they are provided in or near the anaerobic microbial layer M in the methane fermentation tank 31 and in the upper part (near the separation device 32) in the methane fermentation tank 31. Can be mentioned. As a result, the pH in the methane fermentation tank 31 can be grasped with higher accuracy. At this time, the circulation unit 6 may be provided to obtain the stirring effect in the methane fermentation tank 31, or the pH adjustment unit 5 may perform the pH adjustment treatment without providing the circulation unit 6. This makes it possible to simplify the structure of the reaction unit 3.

A methane fermentation treatment will be described as an anaerobic treatment method using the anaerobic treatment device in the present embodiment. The anaerobic treatment apparatus is described based on the structure shown in FIG. 1, but is not limited thereto.

When the methanogenic treatment is performed in the acid-producing tank 2 and the reaction unit 3, the acid-producing bacteria contained in the acid-producing tank 2 decompose high-molecular organic substances such as sugars and proteins in the waste WO to decompose monosaccharides and amino acids. , Methanogenesis that produces methane from carbon sources such as monosaccharides, amino acids, lower fatty acids and acetic acid in the waste WO by the acid production step that produces lower fatty acids and acetic acid and the methanogenic bacteria housed inside the methane fermenter 31. Depending on the process, methane fermentation proceeds (reaction step).

At this time, when the component contained in the wastewater WO is a high-concentration lower alcohol or an organic acid, there are few targets for decomposition by the acid-producing bacteria, and the acid-producing step in the acid-producing tank 2 hardly proceeds. Therefore, the fluctuation of pH with the progress of the acid production step in the acid generation tank 2 is reduced. Therefore, the pH adjustment in the acid generation tank 2 is unnecessary except when the pH of the waste water WO is a strong acid or a strong alkali. On the other hand, in the methane fermenter 31, the pH in the methane fermenter 31 decreases due to the progress of the methanogenic step by the methanogen, the organic acid production by the decomposition of the lower alcohol, and the carbon dioxide production by the decomposition of the organic acid. To go. As described above, it is known that the preferable pH of the methane production step in the methane fermentation tank 31 is near neutral. Here, the pH of the water to be treated W1 in the methane fermentation tank 31 is measured by the pH measuring unit 4 provided in the methane fermentation tank 31 (pH measurement step), and when the measurement result does not satisfy the suitable pH range, The pH adjusting unit 5 adjusts the pH of the water to be treated W1 in the methane fermentation tank 31 (pH adjusting step). As a result, the inside of the reaction unit 3 can be maintained under conditions suitable for the methane fermentation step, and a decrease in anaerobic treatment efficiency can be suppressed.

As described above, by using the anaerobic treatment apparatus and the anaerobic treatment method of the present embodiment, the pH fluctuation in the methane fermentation step can be grasped with high accuracy, and the pH of the water to be treated used in the methane fermentation step can be adjusted. This makes it possible to maintain conditions suitable for the methane fermentation process. This makes it possible to suppress a decrease in the anaerobic treatment efficiency in the anaerobic treatment apparatus and the anaerobic treatment method that perform the anaerobic treatment.

Further, in the present embodiment, as the wastewater WO to be treated, the wastewater WO containing a large amount of lower alcohol, acetic acid, etc. in the wastewater WO and having few treatment targets in the acid generation step has been described, but the wastewater WO is not limited to this. Absent. The anaerobic treatment apparatus and anaerobic treatment method of the present embodiment are preferably used for wastewater containing other components that require high-precision pH fluctuations and pH adjustment in the methane fermentation step as treatment targets. be able to.

[Second Embodiment]
FIG. 2 is a schematic explanatory view of the anaerobic treatment device 1b according to the second embodiment of the present invention.
As shown in FIG. 2, the anaerobic treatment device 1b according to the present embodiment is provided with the pH adjusting unit 5 in the anaerobic treatment device 1a of the first embodiment on the acid generation tank 2 side, and the water to be treated in the reaction unit 3 is provided. The pH adjustment treatment is indirectly performed on W1.
Of the configurations of the anaerobic treatment device 1b in the present embodiment, the same as the configuration of the anaerobic treatment device 1a in the first embodiment will be omitted. Further, in FIG. 2, the description of the circulating water WR and the line L4 is omitted.

In the anaerobic treatment apparatus 1b of the present embodiment, the pH of the reaction unit 3 is measured by the pH measuring unit 4, and the pH adjusting agent adding unit 52 provided in the acid generation tank 2 is controlled based on the measurement result to control the acid generation tank. A pH adjusting agent 51 is added to the wastewater WO in 2 to perform a pH adjusting treatment.

In the anaerobic treatment apparatus 1b of the present embodiment, the pH-adjusted wastewater WO is subjected to an acid generation step and then introduced into the reaction unit 3 as water to be treated W1 via the line L. At this time, the amount of the pH adjuster 51 added is controlled so that the pH of the water to be treated W1 is in the pH range suitable for the methane fermentation step. This makes it possible to adjust the pH of the water to be treated W1 in the reaction unit 3.

The pH adjusting unit 5 provided on the acid generation tank 2 side adjusts the pH of the water to be treated W1 in the reaction unit 3 so as to be in the pH range suitable for the methane fermentation step, and as a result, the inside of the acid generation tank 2 The waste WO is neutralized to meet the pH range suitable for the acid production process. Therefore, in the anaerobic treatment apparatus 1b of the present embodiment, the pH of the waste water WO in the acid generation tank 2 and the pH of the water to be treated W1 in the methane fermentation tank 31 can be adjusted by one pH adjusting unit 5. It will be possible. As a result, the structure of the anaerobic treatment apparatus 1b can be simplified, and control for a plurality of steps related to the anaerobic treatment can be executed more easily.

The anaerobic treatment apparatus 1b in the present embodiment grasps the pH fluctuation in the methane fermentation step with high accuracy, and adjusts the pH of the wastewater in the acid generation tank based on the pH in the methane fermentation step to generate acid. It is possible to maintain conditions suitable for the process and the methane fermentation process.
Further, using the anaerobic treatment device 1b of the present embodiment, the anaerobic treatment can be performed based on the same steps as the anaerobic treatment method described in the first embodiment.
This makes it possible to suppress a decrease in the anaerobic treatment efficiency in the anaerobic treatment apparatus and the anaerobic treatment method that perform the anaerobic treatment.

[Third Embodiment]
FIG. 3 is a schematic explanatory view of the anaerobic treatment device 1c according to the third embodiment of the present invention.
As shown in FIG. 3, the anaerobic treatment device 1c according to the present embodiment does not provide the circulation unit 6 in the anaerobic treatment device 1b of the second embodiment, but provides the pH measurement unit 4 in the methane fermenter 31. is there.
Of the configurations of the anaerobic treatment device 1c in the present embodiment, the same configurations as those of the anaerobic treatment device 1b of the second embodiment will be omitted. Further, in FIG. 3, the description of the circulating water WR and the line L4 is omitted.

The anaerobic treatment device 1c of the present embodiment directly measures the pH of the water to be treated W1 by providing the pH measuring unit 4 in the methane fermentation tank 31. This makes it possible to further simplify the structure of the reaction unit 3.

The location of the pH measuring unit 4 in the anaerobic treatment apparatus 1c of the present embodiment is not particularly limited as long as it is in the methane fermenter 31.
For example, a pH measuring unit 4 may be provided in or near the anaerobic microbial layer M, and the pH adjusting unit 5 may perform a pH adjusting process based on the measurement results. This makes it possible to maintain a suitable pH range related to the methane production step in the anaerobic microbial layer M.
Further, a pH measuring unit 4 is provided in the upper part (near the separation device 32) in the methane fermentation tank 31, and the pH adjusting unit 5 performs a pH adjusting process based on the measurement result. As a result, it is possible to determine whether or not the pH of the water to be treated W1 immediately before being discharged from the line L is of appropriate water quality as the treated water W, and the pH is adjusted so that the methane production step proceeds. By doing so, treated water W satisfying an appropriate water quality (pH) can be obtained.

Further, a plurality of pH measuring units 4 may be provided. For example, it may be provided in or near the anaerobic microbial layer M in the methane fermentation tank 31 and in the upper part (near the separation device 32) in the methane fermentation tank 31. As a result, the pH in the methane fermentation tank 31 can be grasped with higher accuracy.

The anaerobic treatment device 1c of the present embodiment simplifies the structure of the device, grasps the pH fluctuation in the methane fermentation process with high accuracy, and adjusts the pH of the wastewater in the acid generation tank based on the pH in the methane fermentation process. By performing the above, it becomes possible to maintain the conditions suitable for the acid production step and the methane fermentation step.
Further, using the anaerobic treatment device 1c of the present embodiment, the anaerobic treatment can be performed based on the same steps as the anaerobic treatment method described in the first embodiment.
This makes it possible to suppress a decrease in the anaerobic treatment efficiency in the anaerobic treatment apparatus and the anaerobic treatment method that perform the anaerobic treatment.

The above-described embodiment shows an example of an anaerobic treatment apparatus and an anaerobic treatment method. The anaerobic treatment device and the anaerobic treatment method according to the present invention are not limited to the above-described embodiment, and the anaerobic treatment device and the anaerobic treatment method according to the above-described embodiment are used without changing the gist described in the claims. It may be deformed.

For example, in the anaerobic treatment apparatus of this embodiment, a pH measuring unit for measuring the pH of the acid generation tank may be separately provided. Further, a pH adjusting unit for adjusting the pH of the wastewater in the acid producing tank may be separately provided based on the measurement result of the pH of the acid producing tank. Even if the pH measuring unit and the pH adjusting unit provided on the reaction unit side and the pH measuring unit and the pH adjusting unit provided on the acid generation tank side each perform the pH adjusting treatment independently. Often, the pH adjusting unit may be controlled by referring to the measurement results of the respective pH measuring units. Thereby, by adjusting not only the pH of the reaction part but also the pH in the acid generation tank, the pH range suitable for the acid generation step can be set, and the decrease in anaerobic treatment efficiency can be suppressed.

Further, in the anaerobic treatment apparatus of the first embodiment, when the pH adjusting agent addition section is provided on the upstream side of the pH measuring section with respect to the circulating section, a flow rate adjusting function is provided on the circulating section on the downstream side of the pH measuring section. , Only the water to be treated whose measurement result of the pH measuring unit satisfies a predetermined pH may be circulated. Examples of the flow rate adjusting function include providing a flow rate adjusting valve on the return line of the circulation section and providing a temporary storage tank for temporarily storing the water to be treated. At this time, a pH adjusting unit is also provided on the acid generation tank side, and the pH of the water to be treated supplied from the acid generation tank is adjusted based on the measurement result of the pH measuring unit of the reaction unit and introduced into the reaction unit. It is preferable that the pH of the water to be treated is within a predetermined range. This makes it possible to control the pH in the reaction section with higher accuracy.

The anaerobic treatment apparatus and anaerobic treatment method of the present invention are used for anaerobic treatment of wastewater containing organic substances. In particular, the anaerobic treatment apparatus and anaerobic treatment method of the present invention are suitably used for anaerobic treatment of wastewater containing lower alcohols and organic acids.

1a, 1b, 1c Anaerobic treatment equipment, 2 acid generation tank, 3 reaction parts, 31 methane fermentation tank, 32 separation equipment, 4 pH measurement part, 5 pH adjustment part, 51 pH adjuster, 52 pH adjuster addition part, 53 Control unit, 6 circulation unit, 61 return line, 62 pump, L1 to L3 line, M anaerobic microbial layer, WO wastewater, W1 treated water, W treated water

Claims (5)

A reaction part that anaerobicizes the wastewater that has passed through the acid generation tank,
A pH measuring unit for measuring the pH of the reaction unit and
It is characterized by comprising a pH adjusting unit for adjusting the pH of the wastewater in the reaction unit by performing a pH adjusting treatment on the wastewater in the reaction unit based on the pH value measured by the pH measuring unit. Anaerobic treatment device. The reaction unit includes a circulation unit that circulates wastewater in the reaction unit.
The anaerobic treatment apparatus according to claim 1, wherein the pH measuring unit and the pH adjusting unit are provided in the circulation unit. A reaction part that anaerobicizes the wastewater that has passed through the acid generation tank,
A pH measuring unit for measuring the pH of the reaction unit and
An anaerobic treatment apparatus comprising: a pH adjusting unit for adjusting the pH of waste water in the reaction unit based on a pH value measured by the pH measuring unit. The pH adjusting unit is characterized in that the wastewater in the acid generation tank is subjected to a pH adjusting treatment based on the pH value measured by the pH measuring unit to adjust the pH of the wastewater in the reaction unit. , The anaerobic treatment apparatus according to claim 3. A reaction step in which the wastewater that has passed through the acid generation tank is anaerobically treated in the reaction section,
A pH measurement step for measuring the pH of the reaction part, and
An anaerobic treatment method comprising: a pH adjusting step for adjusting the pH of waste water in the reaction section based on the pH value measured in the pH measuring step.