JP2017047398A - Anaerobic fluidized bed wastewater treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anaerobic fluidized bed wastewater treatment apparatus capable of stably removing organic matter contained in water to be treated with a high removal rate even when the concentration of the organic matter is lowered.SOLUTION: An anaerobic fluidized bed waste water treatment apparatus of an embodiment has a raw water tank, an organic matter concentration meter, a fluidized bed type reaction vessel, a treated water tank, a treated water supply part, and a control part. The raw water tank stores water to be treated containing organic matter. The organic matter concentration meter is disposed in the raw water tank. The fluidized bed type reaction vessel is provided with a water introduction port for the water to be treated at a lower part thereof, and a water discharge port for treated water from which the organic matter has been removed by bringing the water to be treated and a carrier into contact with each other. The treated water tank stores the treated water. The treated water supply part supplies the treated water to the fluidized bed type reaction vessel. The control part controls the amount of the treat water supplied to the fluidized bed type reaction vessel by the treated water supply part on the basis of the organic matter concentration of the water to be treated measured by the organic matter concentration meter and the amount of the water to be treated supplied to the fluidized bed type reaction vessel.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to an anaerobic fluidized bed wastewater treatment apparatus.

  Anaerobic fluidized bed wastewater treatment equipment and UASB (Upflow Anaerobic Sludge Blanket: Upflow Anaerobic Sludge) Floor) Wastewater treatment equipment is known. Anaerobic fluidized bed wastewater treatment equipment uses a fluidized bed type reaction vessel as a reaction vessel for organic matter removal, and adheres anaerobic microorganisms to the surface of the carrier forming the fluidized bed, thereby increasing the concentration of anaerobic microorganisms. Hold on. On the other hand, the UASB wastewater treatment apparatus keeps the anaerobic microorganisms at a high concentration by causing the anaerobic microorganisms to self-granulate in the reaction tank and forming granules with high sedimentation properties.

  In the anaerobic fluidized bed wastewater treatment device and the UASB wastewater treatment device, it is possible to efficiently treat the organic matter in the wastewater even at a very high load by keeping the anaerobic microorganisms in the reaction tank at a high concentration. In the UASB wastewater treatment apparatus, granules that are self-granulated products of anaerobic microorganisms are used, so that a carrier used in the anaerobic fluidized bed wastewater treatment apparatus is unnecessary. However, in the UASB wastewater treatment equipment, in the case of low-concentration wastewater, the wastewater flow rate increases, so that microorganisms easily flow out of the reaction tank, and the formation of granules is hindered, or the granules are maintained depending on the type of wastewater. In some cases, the processing performance may deteriorate due to dismantling and outflowing from the reaction vessel.

  In contrast, anaerobic fluidized bed wastewater treatment equipment can prevent the outflow of the carrier by controlling the specific gravity of the carrier even in the case of low-concentration wastewater, and is suitable for the type of wastewater by controlling the material and shape. It is possible to increase the adherence of microorganisms. For this reason, the anaerobic fluidized bed wastewater treatment device is an advantageous device for treating organic substances in low-concentration wastewater.

  In general, a fluidized bed type reaction vessel used in an anaerobic fluidized bed wastewater treatment apparatus is filled with a carrier having anaerobic microorganisms attached to the inside, and a carrier (anaerobic microorganism) forming a fluidized bed and a coating. Treated water from which organic substances have been removed is produced by contact with the treated water. The lower part of the fluidized bed type reaction tank is provided with a water inlet for introducing the water to be treated inside, and the upper part is provided with a water outlet for releasing the treated water to the outside. In addition, anaerobic structure in which a part of the treated water discharged from the water outlet of the fluidized bed type reaction tank is supplied to the water inlet of the fluidized bed type reaction tank as water for causing the carrier to flow to form a fluidized bed. Fluidized bed wastewater treatment equipment is known.

  As described above, the anaerobic fluidized bed wastewater treatment device is an advantageous device for treating organic substances in low-concentration wastewater. However, in order to remove low-concentration organic substances with a high removal rate using an anaerobic fluidized bed wastewater treatment device, the processing conditions such as the BOD volume load of the reaction tank and the expansion ratio of the fluidized bed are strictly optimized. There is a need to. When the treatment conditions are different, especially when the concentration of organic matter in the wastewater is reduced, the organic matter removal rate may be greatly reduced. For example, when wastewater with an organic matter concentration of 1000 mg / L flows into an anaerobic fluidized bed wastewater treatment device with optimized treatment conditions for wastewater with an organic matter concentration of 2000 mg / L, the removal rate of organic matter is greatly reduced. was there. In this way, in anaerobic fluidized bed wastewater treatment equipment, when the concentration of organic matter in the wastewater fluctuates due to the operating conditions of the factory from which the wastewater is discharged and the surrounding conditions such as the incorporation of rainwater into the wastewater, especially the organic matter in the wastewater When the concentration is lowered, there is a concern that the processing performance is lowered.

Japanese Patent Laid-Open No. 3-154694

  The problem to be solved by the present invention is to stably remove organic matter contained in wastewater (treated water) such as sewage and industrial wastewater at a high removal rate even when the concentration of the organic matter is reduced. It is to provide an anaerobic fluidized bed wastewater treatment device capable of performing the above.

The anaerobic fluidized bed wastewater treatment apparatus of the embodiment includes a raw water tank, an organic substance concentration meter, a fluidized bed type reaction tank, a treated water tank, a treated water supply unit, and a control unit.
The raw water tank stores water to be treated containing organic matter. The organic substance concentration meter is installed in the raw water tank. The fluidized bed type reaction tank is filled with a carrier having anaerobic microorganisms attached inside, and has a water inlet for the treated water at the lower part, and the treated water and the carrier are in contact at the upper part. An outlet for treated water from which organic substances have been removed is provided. The treated water tank is connected to the water outlet of the fluidized bed type reaction tank and stores treated water discharged from the water outlet. The treated water supply unit is connected to the treated water tank and supplies the treated water to the water inlet of the fluidized bed type reaction tank. The control unit supplies the treated water based on the organic matter concentration of the treated water measured by the organic matter concentration meter and the amount of the treated water supplied to the water inlet of the fluidized bed type reaction tank. The section controls the amount of the treated water supplied to the water inlet of the fluidized bed reactor.

The block diagram which shows the structure of the anaerobic fluidized bed waste water treatment equipment of embodiment. The graph which shows the relationship between the upward flow velocity LV of the water introduce | transduced into the fluidized bed type | mold reaction tank used for the anaerobic fluidized bed wastewater treatment equipment of embodiment, and the expansion ratio of a fluidized bed.

  Hereinafter, the anaerobic fluidized bed waste water treatment equipment of an embodiment is explained with reference to drawings.

  Drawing 1 is a block diagram showing the composition of the anaerobic fluidized bed waste water treatment equipment of an embodiment. In FIG. 1, an anaerobic fluidized bed wastewater treatment apparatus includes a raw water tank 10, a fluidized bed type reaction tank 20, a treated water tank 30, a first pump (treated water supply unit) 40, and a second pump (treated water). Supply unit) 50 and a control unit 60.

The raw water tank 10 is a tank for storing treated water containing organic matter. Examples of water to be treated containing organic substances include sewage, industrial wastewater generated in facilities such as food factories and livestock farms.
The raw water tank 10 is provided with an organic substance concentration meter 11 for water to be treated. The organic matter concentration meter 11 for treated water measures the organic matter concentration of the treated water in the raw water tank 10. As an example of the organic substance concentration meter 11 for to-be-processed water, a TOC (total organic carbon) meter can be mentioned. The organic substance concentration measured by the organic substance concentration meter 11 for water to be treated is sent to the control unit 60.

  The fluidized bed type reaction tank 20 is filled with a carrier 21 having anaerobic microorganisms attached to the inside thereof. A water inlet 23 is provided in the lower part of the fluidized bed reaction tank 20. The water to be treated in the raw water tank 10 and the treated water in the treated water tank 30 are supplied to the water inlet 23. A water outlet 24 is provided in the upper part of the fluidized bed reaction tank 20. The treated water from which the organic matter is removed is discharged to the outside through the water outlet 24 when the water to be treated and the carrier 21 (anaerobic microorganism) come into contact with each other.

  The treated water tank 30 is a tank for storing treated water taken out from the water outlet 24 of the fluidized bed type reaction tank 20. The treated water tank 30 is provided with a treated water organic matter concentration meter 31 for measuring the treated matter organic matter concentration. The organic matter concentration measured by the treated water organic matter concentration meter 31 is sent to the control unit 60. The treated water tank 30 is also provided with an outlet 32 for taking out treated water that has reached a predetermined water level to the outside.

  The first pump (treated water supply unit) 40 is a pump that supplies the treated water stored in the raw water tank 10 to the water inlet 23 of the fluidized bed type reaction tank 20. The amount of water to be treated supplied by the first pump 40 is sent to the control unit 60.

The second pump (treated water supply unit) 50 is a pump that supplies the treated water stored in the treated water tank 30 to the water inlet 23 of the fluidized bed type reaction tank 20. The treated water supplied to the water inlet 23 of the fluidized bed reaction tank 20 acts as water for causing the carrier 21 to flow to form the fluidized bed 22. The supply amount of water to be treated by the second pump 50 is usually an amount in which the expansion ratio of the fluidized bed 22 formed by the carrier 21 of the fluidized bed type reaction tank 20 is larger than 1 and smaller than 2. Here, the expansion ratio of the fluidized bed 22 is the ratio H between the height H ₀ when the carrier 21 does not form the fluidized bed and the height H when the carrier 21 forms the fluidized bed 22. / H means ₀ .

  The expansion ratio of the fluidized bed 22 increases as the upward flow rate of the water introduced into the fluidized bed reaction tank 20 increases. The degree to which the expansion ratio increases depends on the physical properties such as the specific gravity and shape of the carrier 21. Different. The results of measuring the relationship between the upward flow velocity LV of water and the expansion ratio of the fluidized bed for carrier A and carrier B having different physical properties are shown in FIG. From the graph of FIG. 2, it can be seen that the degree to which the expansion ratio of the fluidized bed 22 increases depends on the physical properties of the carrier 21. Therefore, the supply amount of the water to be treated by the second pump 50 is determined in advance by measuring the relationship between the upward flow rate LV of water and the expansion ratio of the fluidized bed for each type of carrier 21 filled in the fluidized bed type reaction tank 20. Therefore, it is preferable to determine in consideration of the measurement result.

  The water to be treated and the treated water may be mixed and supplied to the water inlet 23 of the fluidized bed type reaction tank 20 as mixed water, or separately supplied to the water inlet 23 of the fluidized bed type reaction tank 20. May be.

  The control unit 60 uses the organic matter concentration of the treated water measured by the treated water organic matter concentration meter 11 and the amount of treated water supplied to the water inlet 23 of the fluidized bed type reaction tank 20 by the first pump 40. Based on the above, the amount of treated water supplied to the water inlet 23 of the fluidized bed type reaction tank 20 by the second pump 50 is controlled. However, the amount of the treated water needs to be an amount in which the expansion ratio of the fluidized bed 22 formed by the carrier 21 of the fluidized bed reaction tank 20 is larger than 1 and smaller than 2.

The control unit 60 is further provided with a measurement unit (not shown) that measures the organic substance removal rate. The measuring unit calculates the organic matter removal rate from the following equation from the organic matter concentration of the treated water measured by the treated water organic matter concentration meter 11 and the treated water organic matter concentration measured by the treated water organic matter concentration meter 31. Is calculated.
Organic substance removal rate (%) = (organic substance concentration of treated water−organic substance concentration of treated water) / organic substance concentration of treated water × 100

  When the organic substance removal rate measured by the measurement unit is lower than a predetermined value, the control unit 60 determines the amount of treated water supplied to the water inlet 23 of the fluidized bed reaction tank 20 by the second pump 50. Reduce.

The reason why the organic matter removal rate is improved by reducing the supply amount of the treated water is that the concentration of the organic matter contained in the water (treated water and treated water) introduced into the fluidized bed reactor 20 is increased. This is considered to be because the substrate utilization rate (dS / dt) of the anaerobic microorganisms adhering to the surface of the carrier 21 is increased. That is, when the wastewater treatment by anaerobic microorganisms is studied from the viewpoint of the kinetics of the anaerobic microorganisms, the substrate utilization rate (dS / dt) of the anaerobic microorganisms is expressed by the following equation (1) according to the Monad equation. The
dS / dt = k _max SX / (Ks ⁺ S) (1)
here,
k _max : Maximum specific substrate utilization rate S: Growth rate limiting substrate concentration X: Biomass concentration Ks ⁺ : Half-saturation constant

In Equation (1), k _max and Ks ⁺ are constants. According to equation (1), the substrate utilization rate (dS / dt) of the microorganism correlates with the growth-limiting substrate concentration (S) and the biomass concentration (X). The biomass concentration (X) means the amount of anaerobic microorganisms adhering to the carrier, and this value is considered not to change. On the other hand, the growth rate-limiting substrate concentration (S) means the concentration of organic substances contained in the water introduced into the fluidized bed type reaction tank 20, so that the amount of treated water introduced into the fluidized bed type reaction tank 20 is reduced. To make it bigger. Therefore, according to the formula (1), by reducing the supply amount of the treated water, the growth rate-limiting substrate concentration (S) is increased, and the substrate utilization rate (dS / dt) of the anaerobic microorganisms is increased. It is thought that the removal rate of the is improved.

  The removal processing of the organic matter in the water to be treated by the anaerobic fluidized bed wastewater treatment apparatus of the present embodiment is performed as follows. First, water to be treated is stored in the raw water tank 10, and water that does not substantially contain organic substances is stored in the treated water tank 30. Next, the water stored in the treated water tank 30 is supplied to the water inlet 23 of the fluidized bed type reaction tank 20 using the second pump 50, and the fluidized bed 22 is formed on the carrier 21. After the fluidized bed 21 is formed, the treated water stored in the raw water tank 10 is supplied to the water inlet 23 of the fluidized bed type reaction tank 20 using the first pump 40. The treated water introduced into the fluidized bed reaction tank 20 comes into contact with the carrier 21 (anaerobic microorganisms) to remove organic substances and produce treated water. The treated water is discharged to the outside through the water outlet 24. The treated water released to the outside is stored in the treated water tank 30. When the level of the treated water in the treated water tank 30 reaches the outlet 32, a part of the treated water is taken out through the outlet 32. On the other hand, the treated water stored in the treated water tank 30 is supplied to the water inlet 23 of the fluidized bed reaction tank 20 by the second pump.

  The control unit 60 controls the organic matter concentration in the raw water tank 10, the organic matter removal rate calculated from the organic matter concentration in the treated water and the organic matter concentration in the treated water tank 30, and the first pump 40. The supply amount of the water to be treated sent to the water inlet 23 of the fluidized bed reactor 20 is monitored. And when these values are abnormal, the supply amount of the treated water sent to the water inlet 23 of the fluidized bed type reaction tank 20 by the second pump 50 is controlled. For example, when the concentration of treated water is lower than normal, when the organic matter removal rate is lowered, or when the supply amount of treated water is increased, the control unit 60 normally sets the supply amount of treated water. The second pump 50 is controlled so as to reduce the time. Thereafter, when the concentration of the treated water and the supply amount of the treated water return to the normal time, the control unit 60 controls the second pump 50 to return the supplied amount of the treated water to the normal amount.

  According to the anaerobic fluidized bed wastewater treatment apparatus of the embodiment, the fluidized bed reaction tank 20 is based on the organic matter concentration of the treated water and the amount of treated water supplied to the water inlet 23 of the fluidized bed reaction tank 20. Since the amount of treated water supplied to the water inlet 23 is controlled, the organic matter contained in the water to be treated (drainage such as sewage and industrial wastewater) can be stably removed even when the concentration of the organic matter is reduced. A removal process can be performed.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

[Example 1]
An anaerobic fluidized bed wastewater treatment apparatus having the configuration shown in FIG. 1 was prepared. This anaerobic fluidized bed wastewater treatment apparatus had an organic matter removal rate of 95% when treated water having an organic matter concentration of 2000 mg / L was treated under the following treatment conditions.

(Processing conditions)
Organic matter concentration of treated water in raw water tank 10: 2000 mg / L
BOD volumetric load of fluidized bed reactor 20: 30 kg / m ³ / day Amount of treated water supplied by first pump 40: 10.3 L / day Amount of treated water supplied by second pump 50: 650 L / day Fluidized bed Flow rate of water introduced into the reaction tank 20: 20 m / h
Expansion ratio of fluidized bed 22: 1.2
Residence time of treated water in fluidized bed reactor 20: 1.6h

[Comparative Example 1]
Assuming that the water to be treated treated in Example 1 is diluted with rainwater by a factor of 1/2 and the amount is doubled, the organic matter concentration in the raw water tank 10 is 1000 mg / L. And the removal processing of the organic substance in to-be-processed water was performed like Example 1 except having supplied the amount of to-be-processed water by the 1st pump 40 to 20.6 L / day. As a result, the organic matter removal rate was 85% or less. The processing conditions are shown below.

(Processing conditions)
Organic matter concentration of treated water in raw water tank 10: 1000 mg / L
BOD volumetric load of fluidized bed reactor 20: 30 kg / m ³ / day Amount of treated water supplied by first pump 40: 20.6 L / day Amount of treated water supplied by second pump 50: 650 L / day Fluidized bed Flow rate of water introduced into the reaction tank 20: 20 m / h
Expansion ratio of fluidized bed 22: 1.2
Residence time of water to be treated in the fluidized bed reactor 20: 0.8h

[Example 2]
In the treatment conditions of Comparative Example 1, except that the amount of treated water supplied by the second pump 50 is 288 L / day and the upward flow rate of water introduced into the fluidized bed type reaction tank 20 is 10 m / h, Waste water treatment was performed in the same manner as in Comparative Example 1. As a result, the organic matter removal rate was 90% or more. The processing conditions are shown below.

(Processing conditions)
Organic matter concentration of treated water in raw water tank 10: 1000 mg / L
BOD volumetric load of fluidized bed reactor 20: 30 kg / m ³ / day Amount of treated water supplied by first pump 40: 20.6 L / day Amount of treated water supplied by second pump 50: 288 L / day Fluidized bed Flow rate of water introduced into the reaction tank 20: 10 m / h
The expansion ratio of the fluidized bed 22 slightly exceeds 1: Residence time of water to be treated in the fluidized bed reactor 20: 0.8 h

In Example 1, the organic substance concentration of water (treated water + treated water) introduced into the fluidized bed reactor 20 is about 31 mg / L = 2000 × 10.3 ÷ (10.3 + 650).
In Comparative Example 1, the organic concentration of water introduced into the fluidized bed reactor 20 is about 31 mg / L = 1000 × 20.6 ÷ (20.6 + 650). The reason why the organic matter removal rate in Comparative Example 1 was reduced to 85% or less in Comparative Example 1 was the same as Example 1 and Comparative Example 1 in which the organic matter concentration of water introduced into the fluidized bed reaction vessel 20 was the same. This is probably because the retention time of the water to be treated in the tank 20 was shortened from 1.6 h to 0.8 h.
In Example 2, the organic substance concentration of water introduced into the fluidized bed reactor 20 is approximately 67 mg / L = 1000 × 20.6 ÷ (20.6 + 288). The reason why the organic matter removal rate was improved to 90% or more in Example 2 was the same as in Comparative Example 1 and Example 2 while the residence time of the water to be treated in the fluidized bed type reaction tank 20 was the same. This is probably because the organic substance concentration of the mixed water introduced into the mold reaction tank 20 increased about twice as compared with Comparative Example 1.

  DESCRIPTION OF SYMBOLS 10 ... Raw water tank, 11 ... Organic substance concentration meter for to-be-treated water, 20 ... Fluidized bed type reaction tank, 21 ... Carrier, 22 ... Fluidized bed, 23 ... Water inlet, 24 ... Water outlet, 30 ... Treated water tank, 31 ... Treatment Organic concentration meter for water, 32 ... take-out port, 40 ... first pump (treated water supply part), 50 ... second pump (treated water supply part), 60 ... control part

Claims (3)

A raw water tank for storing treated water containing organic matter;
An organic matter concentration meter installed in the raw water tank;
Treated water filled with a carrier having anaerobic microorganisms attached inside, provided with a water inlet for the treated water at the bottom, and organic matter removed by contacting the treated water with the carrier at the top A fluidized bed reactor equipped with a water outlet,
A treated water tank connected to the water outlet of the fluidized bed reaction tank and storing treated water discharged from the water outlet;
A treated water supply unit connected to the treated water tank and supplying the treated water to the water inlet of the fluidized bed type reaction tank;
Based on the organic matter concentration of the treated water measured by the organic matter concentration meter and the amount of the treated water supplied to the water inlet of the fluidized bed type reaction tank, the treated water supply unit is configured to flow the fluid. An anaerobic fluidized bed wastewater treatment apparatus having a control unit for controlling the amount of the treated water supplied to the water inlet of the bed type reaction tank. The control unit is further provided with a measurement unit that measures an organic matter removal rate of the water to be treated.
The said control part is the said treated water supplied to the said water inlet of the said fluidized bed reaction tank by the said treated water supply part, when the removal rate of the said organic substance measured in the said measurement part is lower than predetermined value. The anaerobic fluidized bed waste water treatment equipment according to claim 1 which reduces quantity.   The control unit is configured such that the amount of the treated water supplied to the water inlet of the fluidized bed type reaction tank by the treated water supply unit is larger than 1 when the expansion ratio of the fluidized bed formed by the carrier is larger than 1. The anaerobic fluidized bed wastewater treatment apparatus according to claim 1 or 2, wherein the anaerobic fluidized bed wastewater treatment apparatus is controlled to a smaller amount.

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