JPH08132091A - Anaerobic treating device - Google Patents

Abstract

PURPOSE: To obtain an anaerobic treating device capable of efficient anaerobic treatment by efficiently collecting the sludge floated up in an anaerobic reaction tank and crushing the sludge to restore its settling property. CONSTITUTION: The inside of a UASB-type anaerobic reaction tank 1 is separated by solid-gas separation membranes 8a and 8b into a solid-liq. separation part 9 on the upper inside, a gas collecting part 10 on the upper outside and a reaction part 11 having a sludge blanket 13 at the lower part. The sludge 32 floated up to the solid-liq. separation part 9 and/or the gas collecting part 10 is sucked by a crusher 16 with the switch part 17 opened upward in the vicinity of the liq. surface and crushed, and the crushed sludge is returned to the reaction part 11 due to its restored settling property.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention uses organic waste liquid UASB.
The present invention relates to an anaerobic treatment device for anaerobic treatment by the (upstream sludge blanket) method.

As a method of anaerobic treatment of organic waste liquid, a granular sludge having a high density and a large sedimentation property is formed, and an organic waste liquid containing soluble BOD is upwardly circulated to form a sludge blanket. The UASB method is employed in which high-load and high-speed processing is performed by contacting each other in a state. In this method, solid organic matter with a slow digestion rate is separated and treated separately, and only soluble organic matter with a fast digestion rate is treated at high speed with high load by anaerobic treatment using granulated sludge with high anaerobic microorganism density. It is a method and is distinguished from the traditional anaerobic treatment.

The conventional anaerobic digestion method is a method in which an organic waste liquid containing a solid organic matter and a soluble organic matter is directly introduced into a digestion tank for anaerobic digestion, which is a long process in the step of solubilizing the solid organic matter. Since it takes time, 20-4 as a whole
A long residence time of 0 days is required, and a large processing device is required. On the other hand, since the UASB method uses a granular sludge in which highly active anaerobic microorganisms are accumulated and has a large sedimentation property, solid-liquid separation is improved even at a high flow rate, and a large amount of sludge is stored in the tank. By holding it and maintaining the sludge concentration in the tank at a high level, anaerobic treatment can be performed with high treatment efficiency, and treatment can be performed efficiently using a small apparatus.

[0004] In the anaerobic digestion method, sludge is fine and light, and thus the generated gas adheres and floats to form scum on the liquid surface, but when the scum is crushed by stirring and the sludge and gas are separated, Sludge settles and scum formation is prevented. On the other hand, in the UASB method, since the sludge that is granulated and has a good sedimentation property is used, the sludge usually does not float up with the digested gas to form scum unlike the anaerobic digestion method, and therefore scum is not generated. It is said that there is no need to perform the operation of crushing and returning to the reaction section, and the operation operation is simple.

However, among UASB type anaerobic treatment apparatuses, a BOD load amount of 10 kg / m ³ ·
In a device that performs high-load treatment of d or more, a phenomenon in which the granular sludge floats up to form scum, the floating sludge flows out into the treated water, and the sludge holding amount in the anaerobic reaction tank decreases is observed. . When this sludge floats or flows out, the treatment becomes insufficient, making it difficult to perform high-load operation, which is a characteristic of the UASB system, and anaerobic sludge flows into the activated sludge treatment device that is the post-treatment of the UASB system. The DO of the aeration tank is significantly reduced, and the treatment performance of the activated sludge treatment device is reduced. The above-mentioned sludge flotation is similar in phenomenon to that of the scum in the conventional anaerobic digestion method, but unlike the flocculation that accompanies the adhered gas like scum, it does not This is because the specific gravity is small, and just by removing the gas adhering to the outside like a conventional scum breaker, the sedimentation property cannot be recovered.

Most of the granular sludge floating in the UASB type anaerobic reaction tank has a small specific gravity because the gas generated by the anaerobic reaction is contained inside the granular sludge. There are many cases where Therefore, by crushing the granular sludge enclosing the gas, it is possible to release the gas in the encapsulated state and form a blanket, which is the original existing form of the granular sludge. Therefore, in a UASB-type anaerobic treatment device, the granular sludge floating in the reaction tank is appropriately discharged to the outside of the reaction tank, and the discharged sludge is crushed using a crushable pump, mixer, homogenizer, etc. Attempts have been made to return the film to the reaction tank in an exposed state (for example, JP-A-6-182382).

[0007]

However, the recent anaerobic treatment device has a completely closed structure from the viewpoint of odor control, and it is difficult to efficiently collect the sludge floating in the reaction tank. In many cases, the floating granulated sludge is left in the reaction tank for a long period of time. Therefore, the floating sludge flows out together with the treatment liquid, and the retained amount of the granulated sludge forming a good blanket in the reaction tank gradually decreases, which makes normal anaerobic treatment difficult. Even when a sludge collecting device such as a gas injection nozzle on the liquid surface of the solid-liquid separation unit is provided as in the above publication, it is difficult to efficiently take out the floating sludge because the operating condition cannot be confirmed in the reaction tank having a closed structure. There is a problem that is.

The object of the present invention is to solve the above-mentioned problems in the UASB method and to efficiently collect and crush the sludge in the reaction tank even when the granulated sludge floats, thereby improving the sedimentation property. An object of the present invention is to provide an anaerobic treatment device capable of performing treatment with high treatment efficiency by recovering and returning to the reaction section, thereby maintaining a high sludge concentration in the tank.

[0009]

DISCLOSURE OF THE INVENTION The present invention has an anaerobic reaction tank having a reaction section in which a sludge blanket made of granulated sludge containing anaerobic microorganisms is formed, and having a treated liquid inflow section at the bottom. A solid-gas separation member that is installed at an upper portion of the reaction section so as to separate the solid-liquid separation section and the gas collection section, and a communication path that connects the lower section of the solid-liquid separation section and the reaction section. The processing liquid outlet is provided near the liquid surface of the solid-liquid separation unit, and the suction unit is attached to the gas collection unit and / or near the liquid surface of the solid-liquid separation unit so as to open upward, and sucks from the suction unit. An anaerobic treatment device comprising: a crushing device for crushing the floating sludge and returning it to the reaction section.

Although the growth process of the granulated sludge in the UASB method is not clear, anaerobic microorganisms are present on the surface of fine inorganic SS having a particle diameter of about 0.1 mm and the surface of scale components containing calcium and magnesium. When attached, new anaerobic microorganisms grow and attach in an annual ring shape with the minute SS and scale as the nucleus, and when it takes several months or more to grow into granular sludge with a particle size of 0.5 to 1 mm. Has been done. It is said that the grown granular sludge is crushed by the flow of water and gas generated in the reaction tank, and the crushed fine particles and fragments serve as nuclei to grow the next granular sludge.

When the grown granular sludge is not crushed, or when the crushed ratio or degree is small, as the sludge continues to grow and the particle size becomes 1 mm or more, the inside of the granular sludge becomes larger. Anaerobic microorganisms and organic SS components self-decompose. Then, after self-decomposition, it becomes hollow, and the gas generated by the methanogenic reaction is accumulated in the hollow, and the specific gravity of the granulated sludge is reduced by the enclosed gas, and as a result, the granular sludge floats up and flows out. Conceivable.

When the load amount in the UASB method is large,
The growth of granulated sludge and the rate of crushing of the grown sludge are balanced, so the proportion of granulated sludge that grows to a large particle size and contains gas is small, and the sludge floats, The outflow phenomenon is not remarkable. On the other hand, when the treatment is performed at a high BOD load of 10 to 15 kg / m ³ · d, the growth rate of the granulated sludge is
The rate is much higher than the rate of shredding, and sludge floating and runoff phenomena increase. Therefore, when the UASB system operates under high load, scale components with a high specific gravity and inorganic SS
Unless sludge is constantly supplied, the floating phenomenon of granulated sludge occurs.

Therefore, in the present invention, the flotation sludge is efficiently collected in the reaction tank and appropriately crushed to reduce the average particle size of the flotation sludge, and at the same time, the hollow portion inside is exposed to the outer surface. In order to recover the settling property and maintain the sludge concentration in the tank at a high level, a crushing device is provided in the gas collection section and / or the solid-liquid separation section so that the suction section opens upward near the liquid surface. It is configured to crush the floating sludge sucked in from and return it to the reaction section. The anaerobic reaction tank in the UASB method has a closed structure as a countermeasure against odorous gases such as organic acids and sulfur compounds that are generated. In order to efficiently collect floating sludge from the anaerobic reaction tank having such a closed structure, In the present invention, the floating sludge is sucked and crushed by utilizing the suction force of the crusher. In this case, the crushing device is installed at a position slightly lower than the liquid surface so that the suction part opens upward.

A pump having a crushing mechanism such as a grinder pump can be used as the crushing device. Such a crushing device may be provided in both the gas collecting part and the solid-liquid separating part of the anaerobic reaction tank, or may be provided in either one. When the crushing device is provided in the gas collection part, it is preferable to collect the floating sludge in the solid-liquid separation part, transfer it to the gas collection part by a pump, a gas lift or the like and crush it. If a crushing device is installed in the solid-liquid separation unit, the floating sludge in the gas collection unit is in a fluid state and may eventually enter the solid-liquid separation unit. However, when transferring, it is preferable to directly introduce the crushing device.

[0015]

In the method for anaerobic treatment using the anaerobic treatment apparatus of the present invention, first, the granulated sludge containing anaerobic microorganisms granulated by utilizing the self-granulating property of the anaerobic microorganisms is stored in the anaerobic reaction tank. It is charged into the reaction part, and the organic drainage is introduced from the treated liquid inflow part provided in the bottom part, and is passed in the upward flow to form a sludge blanket, which is contacted under anaerobic conditions. As a result, the soluble organic matter in the effluent is decomposed into methane and carbon dioxide by the action of the anaerobic microorganisms through the acid producing step and the methane producing step.

Since the granular sludge has a high density and an excellent settling property, a uniform sludge blanket is formed by passing the waste liquid in an upward flow and retained in the reaction section. The waste liquid that has passed through the sludge blanket enters the solid-liquid separation portion from the communication passage, is separated into the solid-liquid portion there, and the separated liquid is taken out as the processing liquid from the processing liquid take-out portion. The separated sludge settles and returns from the communication passage to the reaction section. Gas such as methane generated in the reaction section rises in the reaction section, but is blocked by the solid-gas separation member and does not flow into the solid-liquid separation section, but is taken out from the gas collection section.

In a normal operating condition when the load is relatively low, the granulated sludge does not float up, and the sludge that has flowed into the solid-liquid separation section settles as it is and returns to the reaction section, but when operating under a high load Alternatively, when the operation is continued for a long period of time, the apparent specific gravity of the granulated sludge becomes small and floats, and then floats on the liquid surface of the gas collection part or the solid-liquid separation part. Therefore, in the present invention, the floating sludge that has floated in the gas collection section and / or the solid-liquid separation section is sucked by the crushing device and collected and crushed. In this case, since the suction part of the crushing device is open upwards near the liquid surface, the floating sludge moves on the liquid surface and is collected and sucked into the suction part of the crushing device and crushed to the reaction part. Will be returned.

In the present invention, the anaerobic reaction is performed while the floating sludge is collected by the crushing device, crushed and returned to the reaction section in this way. The floating sludge has a hollow portion inside, so if you crush it so that the hollow portion is exposed on the surface,
The granulated sludge returns to its original state of high specific gravity, and the sedimentation property is restored. Regarding the degree of crushing at this time, most of the crushed sludge has a particle size of 0.2 to 1 mm, preferably 0.3 to 0.
It is suitable to set it to about 7 mm. If the particle size of the crushed sludge is less than 0.2 mm, it tends to flow out together with the treatment liquid, and if it exceeds 1 mm, it is not preferable because the hollow portion is not exposed and the sedimentation property is not recovered in many cases.

In the case of crushing with a grinder pump having a sludge crushing mechanism, the crushing degree according to the number of rotations and the amount of liquid passing must be confirmed beforehand, and the number of rotations and the amount of liquid passing must be suitable for the appropriate crushing situation. It is preferable to drive. The proper crushing condition can be checked and adjusted by measuring the particle size of crushed sludge.

If the treatment is continued without crushing the floating sludge as described above, the floating sludge flows out together with the treated water, and the sludge amount decreases and the treatment efficiency decreases, but the sludge is crushed to the reaction section. By returning, sludge concentration in tank (amount of sludge in tank /
The reaction volume) remains high. Sludge concentration in the tank is 300
It can be maintained at 00 mg-VSS / l or more. The organic waste liquid to be treated in the present invention is a waste liquid containing a soluble organic substance, and may contain some solid organic substance.
When a large amount of solid organic matter is contained, the solid organic matter removed in advance by solid-liquid separation is subjected to treatment.

Although the present invention is applied to a high load anaerobic treatment apparatus by the UASB method, it does not depend on the operating temperature of the UASB apparatus, and the treatable temperature is from 20 ° C to 45 ° C.
The present invention can be applied to either the intermediate temperature treatment which is between 0 ° C or the high temperature treatment which has a temperature range capable of being treated at 45 ° C or higher. The upward flow velocity of the drainage in the anaerobic treatment tank is 0.5 to
2 m / hr, preferably 1 to 1.5 m / hr, and a residence time of 4 to 48 hours, preferably 6 to 24 hours are suitable.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments of the drawings. FIG. 1 is a sectional view of a UASB type anaerobic treatment apparatus of the embodiment, and FIG. 2 is a sectional view of a crushing apparatus. In FIG.
1 is an anaerobic reaction tank, which is composed of a rectangular parallelepiped container,
A liquid to be treated inflow portion 2 is uniformly provided on the bottom portion and communicates with a liquid to be treated introducing passage 3. The upper part of the anaerobic reaction tank 1 is covered with a cover 4 to form a gas chamber 5 having a closed structure,
The gas extraction path 6 is connected to the top thereof.

A liquid chamber 7 is formed below the gas chamber 5 in the anaerobic reaction tank 1, and a solid gas composed of first and second partition plates inclined in opposite directions is formed above the liquid chamber 7. Separation members 8a, 8
b is arranged, and a solid-liquid separating section 9 is partitioned inside the upper part, a gas collecting section 10 is partitioned outside the upper part, and a reaction section 11 is partitioned below. The lower ends of the solid-gas separating members 8a and 8b are isolated from each other to form a communication passage 12, and one lower end covers the lower side of the other lower end so that the floating gas flows from the communicating passage 12 to the solid-liquid separation unit 9. It has a structure that prevents entry.

The organic waste liquid is introduced into the liquid chamber 7 in the anaerobic reaction tank 1, and the sludge blanket 13 is formed in the reaction section 11. An overflow type treatment liquid take-out portion 14 is provided in the liquid surface portion near the upper portion of the communication passage 12 above the solid-liquid separation portion 9 and communicates with the treatment liquid take-out passage 15. A crushing device 16 is provided in the vicinity of the liquid surface of the gas collecting portion 10, the suction portion 17 thereof opens upward to a portion slightly below the liquid surface, and the crushed sludge discharge portion 18 opens into the liquid, It is arranged to return the crushed sludge to the section 11.

The crushing device 16 is, as shown in the figure, a suction unit 1
On the 7 side, a grinder disk 20 having a fixed blade 19 is opposed to a grinder impeller 22 having a rotary blade 21 to form a crushing section 23, and a casing 24 communicating with the crushing section 23 and the crushed sludge discharge section 18 is provided. An impeller 25 is provided inside and a pump portion 26 is formed. A rotary shaft 27 that penetrates the grinder impeller 22 and the impeller 25 is sealed by a shaft sealing device 28 and is connected to be rotated by a motor 29. A support leg 30 projects from the casing 24 in the opening direction of the suction portion 17, and is suspended from the cover 4 by a suspension member 31.

This crushing device 16 is generally commercially available, and is normally supported below the surface of the water by the support legs 30, and the suction unit 1
7 is used so that sludge or the like is sucked downward and crushed to discharge the crushed sludge upward from the crushed sludge discharge portion 18. In the present invention, the crushed sludge is arranged upside down and used. To enable efficient suction and crushing of floating sludge.

In the anaerobic treatment method using the above anaerobic treatment apparatus, first, a granular sludge containing anaerobic microorganisms granulated by utilizing the self-granulating property of anaerobic microorganisms is used as a reaction part of the anaerobic reaction tank 1. Put in 11. Then, the organic waste liquid is introduced from the liquid to be treated introduction passage 3 into the liquid to be treated 2 provided at the bottom of the anaerobic reaction tank 1, and the sludge blanket 13 is formed by passing the liquid in an upward flow to form an anaerobic gas. The anaerobic reaction is carried out by contacting under sex. As a result, the soluble organic matter in the effluent is decomposed into methane and carbon dioxide by the action of the anaerobic microorganisms through the acid producing step and the methane producing step.

Since the granular sludge has a high density and an excellent settling property, a uniform sludge blanket 13 is formed by passing the waste liquid in an upward flow, and is retained in the reaction section 11. The organic waste liquid that has passed through the sludge blanket 13 enters the solid-liquid separation unit 9 from the communication passage 12, and is separated into solid-liquid there, and the separated liquid overflows from the processing liquid take-out unit 14 and becomes a processing liquid take-out path 15 as a processing liquid. Taken out. The separated sludge settles down, and the reaction passage 1 passes through the communication passage 12.
Return to 1. Gas such as methane generated in the reaction section 11 rises in the reaction section 11, but is blocked by the solid-gas separation members 8a and 8b and does not flow into the solid-liquid separation section 9, but is collected in the gas collection section 10. It is taken out from the gas chamber 5 to the gas take-out path 6.

In a normal operating condition with a low load, the granulated sludge does not float on the liquid surface, and the sludge flowing into the solid-liquid separation section 9 settles as it is and returns to the reaction section 11.
When the operation is performed under a high load, or when the operation is continued for a long time, the apparent specific gravity of the granulated sludge becomes small and floats, and floats on the liquid surface of the solid-liquid separation section 9.

In this case, the floating sludge in the reaction section 11 rises as it is and floats on the liquid surface of the gas collecting section. The floating sludge 32 thus floated is sucked from the suction part 17 by the rotation of the motor 29 of the crushing device 16 and crushed by the crushing part 23,
Centrifugal force is applied to the crushed sludge by the pump unit 26, the crushed sludge discharge unit 18 discharges the crushed sludge into the liquid, and the crushed sludge is returned to the reaction unit 11.

Since the levitation sludge has a hollow portion formed inside, by crushing so that the hollow portion is exposed on the surface, the original sludge is returned to a state where the specific gravity is large and the sedimentation property is recovered. In this way, by performing the anaerobic reaction while crushing the floating sludge and returning it to the reaction section 11, the sludge concentration in the tank is kept high and the treatment efficiency is kept high.

Since the floating sludge mainly floats on the gas collecting section 10, when the gas collecting section 10 is crushed, the amount of floating sludge entering the solid-liquid separating section 9 decreases, but it floats on the solid-liquid separating section 9. When sludge floats up, the floating sludge take-out section is provided on the liquid surface of the solid-liquid separation section and transferred to the gas collection section 10 by a pump, or when transferred to the gas collection section by a gas lift that uses the generated gas. The sludge can be crushed by the crushing device. Of course, the solid-liquid separation unit 9 may be provided with the crushing device 16 to crush the floating sludge.

[0033]

As described above, according to the present invention, the floating sludge that has floated in the anaerobic reaction tank is sucked into the crushing device whose suction portion opens upward near the liquid surface, crushed, and returned to the reaction portion. Therefore, the floating sludge can be efficiently collected and crushed in the reaction tank to recover the sedimentation property and efficiently perform the anaerobic treatment.

[Brief description of drawings]

FIG. 1 is a sectional view of an anaerobic treatment apparatus according to an embodiment.

FIG. 2 is a cross-sectional view of a crushing device according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anaerobic reaction tank 2 Processed liquid inflow part 3 Processed liquid introduction path 4 Cover 5, 5a Gas chamber 6 Gas extraction path 7, 7a Liquid chamber 8a, 8b Solid-gas separation member 9 Solid-liquid separation part 10 Gas collection part 11 Reaction part 12 Communication passage 13 Sludge blanket 14 Treatment liquid take-out part 15 Treatment liquid take-out route 16 Crushing device 17 Suction part 18 Crushing sludge discharge part 19 Fixed blade 20 Grinder disk 21 Rotating blade 22 Grinder impeller 23 Crushing part 24 Casing 25 Impeller 26 Pump unit 27 Rotating shaft 28 Shaft sealing device 29 Motor 30 Support leg 31 Hanging member 32 Floating sludge

Claims (1)

[Claims] 1. An anaerobic reaction tank having a reaction part in which a sludge blanket made of granulated sludge containing anaerobic microorganisms is formed, and an inflow part for liquid to be treated at the bottom, and an upper part of the reaction part. A solid-gas separation member that is installed so as to separate the solid-liquid separation unit and the gas collection unit, a communication passage that connects the lower part of the solid-liquid separation unit and the reaction unit, and the vicinity of the liquid surface of the solid-liquid separation unit Is installed so that the suction part opens upward near the liquid surface of the gas collection part and / or the solid-liquid separation part, and the sludge sucked from the suction part is crushed and reacted. An anaerobic treatment device comprising: a crushing device for returning to a part.