JPH08103794A - Anaerobic treatment device - Google Patents

Abstract

PURPOSE: To provide an anaerobic treatment device which can takeout suspended sludge having been lifted up and crush it efficiently to restore its precipitating property, returns it to a reaction section, whereby the sludge can be prevented from flowing out and the concentration of the sludge in a reactor can be enhanced thereby to efficiently achieve an anaerobic processing. CONSTITUTION: A reaction zone 11 is formed, in an anaerobic treatment reactor 1 of UASB system, to have a solid-liquid separation section 9 inside the upper section of the reactor, a gas collecting section 10 outside the upper section, and a sludge blanket 13 in the lower section, the sections being separated by solid-liquid separation members 8a, 8b, and a suspended sludge takeout section 14 of the overflow type is provided near the upper part of a communicating passage 12 and a baffle is provided between the section 14 and a treated liquid takeout section 16 so that the suspended sludge taken out from the section 14 is crushed by a crushing device 21 to return it to the reaction zone 11.

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.

[0002]

2. Description of the Related Art 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 flowed to form a sludge blanket. The UASB method is employed in which the high-load and high-speed processing is performed by bringing them into contact with each other in the formed 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 granule-like sludge in which highly active anaerobic microorganisms are accumulated and has a large settling property, solid-liquid separation is improved even at high flow rates, and a large amount of sludge is retained in the tank. However, the sludge concentration in the tank can be maintained high, and thus the anaerobic treatment can be performed with high treatment efficiency, and the treatment can be efficiently performed 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 the UASB type anaerobic treatment apparatuses, a BOD load 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 even when the granular sludge floats up, the sludge is efficiently taken out and the sedimentation property is recovered and returned to the reaction section. An object of the present invention is to provide an anaerobic treatment device capable of maintaining high sludge concentration in a tank and performing treatment with high treatment efficiency.

[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. And a solid-gas separation member disposed on the upper part of the reaction part so as to be inclined so as to separate the solid-liquid separation part and the gas collection part, and a communication passage for connecting the lower part of the solid-liquid separation part and the reaction part. An overflow type floating sludge take-out section provided in the solid-liquid separation section near the upper part of this communication passage,
An overflow type treatment liquid take-out portion provided in a solid-liquid separation portion at a position apart from the upper part of the communication passage, and a baffle provided near the liquid surface between the treatment liquid take-out portion and the floating sludge take-out portion, An anaerobic treatment apparatus, comprising: a crushing device for crushing the granular sludge taken out from the floating sludge taking-out part and returning it to the reaction part.

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 low,
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 floating sludge is efficiently taken out and appropriately crushed to reduce the average particle size of the floating sludge, and at the same time, the cavitation inside is exposed to the outer surface to recover the sedimentation property. , It is configured to maintain a high sludge concentration in the tank. The anaerobic reaction tank in the UASB method, as a countermeasure against odorous gases such as organic acids and sulfur compounds generated,
Although it has a closed structure, in order to efficiently take out the floating sludge from the anaerobic reaction tank having such a closed structure, in the present invention, the overflow occurs in the solid-liquid separation section near the upper part of the communication passage between the solid-liquid separation section and the reaction section. The floating sludge take-out section is provided, the overflow-type processing liquid take-out section is provided in the solid-liquid separation section located away from the upper part of the communication passage, and the baffle is provided near the liquid surface between the take-out sections.

It is preferable that the floating sludge take-out part is opened at a position lower than the treatment liquid take-out part. As the crushing device, a pump having a crushing mechanism such as a grinder pump, a mixer or a homogenizer can be used. It is preferable that the crushing device is arranged at a position lower than the floating sludge take-out part, and the floating sludge is configured to move in a downflow type.

[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.

Under normal operating conditions when the load is comparatively 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 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. In the gas collection part, the liquid surface is disturbed by the generated gas, so that even if the specific gravity of the granulated sludge is small, it can be easily circulated to the reaction part as it is.

In the present invention, the anaerobic reaction is carried out while taking out the floating sludge floating in the solid-liquid separation section from the floating sludge take-out section, crushing it in the crushing apparatus and returning it to the reaction section. The floating sludge is blocked by the baffle and does not flow out from the treated liquid outlet. 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 easily flows out together with the treatment liquid, and if it exceeds 1 mm, the hollow portion is not exposed,
It is not preferable because the sedimentation property is often not recovered.

When crushing with a pump having a sludge crushing mechanism, a special pump having a vortex system or a foreign matter crushing mechanism is used to check the crushing degree in advance, and the rotation speed suitable for the appropriate crushing situation. It is preferable to operate at a flow rate of or. The proper crushing condition can be checked and adjusted by measuring the particle size of crushed sludge. Even when a mixer, a homogenizer or the like is used for crushing, it is preferable to adjust the stirring strength while checking the crushing condition.

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 100
It can be maintained at 00 mg / 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 reaction 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 according to an embodiment. In the figure, 1 is an anaerobic reaction tank,
It is composed of a rectangular parallelepiped container, and the liquid to be treated inflow portion 2 is uniformly provided at the bottom thereof and communicates with the liquid to be treated introducing passage 3. An upper part of the anaerobic reaction tank 1 is covered with a cover 4 to form a gas chamber 5 having a closed structure, and a gas extraction path 6 is connected to the top of the gas chamber 5.

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 path 12, and one lower end covers the lower side of the other lower end so that the floating gas can flow from the communicating path 12 into the solid-liquid separation section 9a. It is structured to prevent 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 floating sludge take-out section 14 is provided on the liquid surface portion of the upper part of the solid-liquid separation section 9 immediately above the communication passage 12, and is connected to the floating sludge take-out path 15. Further, an overflow-type processing liquid take-out portion 16 is provided on the solid-gas separation members 8a, 8b side of the solid-liquid separation portion 9 above the communication passage 12 immediately above.
It communicates with the processing liquid outlet 17. Flotation sludge removal unit 14
Is provided at a position 1 to 5 cm lower than the treatment liquid outlet 16, and a baffle 18 is provided near the treatment liquid outlet 16 near the liquid surface between the two outlets 14, 16.

Reference numeral 21 is a crushing device, which has a gas chamber 5a formed in the upper part and a liquid chamber 7a formed in the lower part, and a pressure equalizing pipe 22 is connected from the gas chamber 5 of the anaerobic reaction tank 1 to the gas chamber 5a. 7a
The flotation sludge take-out path 15 is in contact with. Also, the liquid chamber 7a
A crushing pump 23 is provided in the tank, and a sludge return passage 24 communicates with the liquid chamber 7 of the anaerobic reaction tank 1. The crushing pump 23 can adjust the crushing strength by adjusting the number of revolutions and the amount of liquid passing, and the particle size of the crushed sludge is adjusted to 0.3 to 0.7 mm. If the particle size of the is outside the above range, it can be corrected.

In the anaerobic treatment method using the above anaerobic treatment apparatus, first, the granular sludge containing the anaerobic microorganisms granulated by utilizing the self-granulating property of the anaerobic microorganisms is used as the 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 extraction unit 16 and is treated as a processing liquid extraction passage 17. 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.

Under normal operating conditions 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 buoyant sludge that has entered the solid-liquid separation section 9 from the communication passage 12 directly rises as it is, and is overflowed and taken out from the levitation sludge unloading section 14 located immediately above the communication passage 12 to remove the levitation sludge. It is introduced into the crushing device 21 from the take-out path 15.

Since the floating sludge is blocked by the baffle 18 and does not reach the treatment liquid extraction section 16, it does not flow out to the treatment liquid extraction passage 17. Since the gas chambers 5 and 5a are kept at a uniform pressure by the pressure equalizing pipe 22 and the floating sludge take-out part 14 is opened at a position lower than the treatment liquid take-out part 16, the floating sludge is transferred to the crushing device 21 at a substantially constant flow rate. To be done.

In the crushing device 21, the introduced floating sludge is crushed by the crushing pump 23 and returned to the reaction section 11 from the sludge returning passage 24. The floating sludge has a hollow portion inside, so by crushing it so that the hollow portion is exposed on the surface, it returns to its original high specific gravity state.
Settling property is restored. By thus crushing the floating sludge and performing the anaerobic reaction while returning the sludge to the reaction section 11, the sludge concentration in the tank is kept high and the treatment efficiency is kept high.

In the above apparatus, since the floating sludge take-out section 14 is provided in the vicinity of the upper part of the communication passage 12, the communication passage 1
The buoyant sludge that has passed through 2 is directly lifted up and taken out from the buoyant sludge take-out section 14. Further, the treatment liquid take-out section 16 is arranged at a position away from the upper part of the communication passage 12, and the baffle 18 is provided between the floating sludge take-out section 14 and the treatment liquid take-out section 16. It is prevented from flowing out.

The floating sludge take-out section 14 is the treated liquid take-out section 1.
Since the sludge is opened at a position lower than 6, it is possible to prevent the floating sludge from being taken out by a fixed amount and staying in the solid-liquid separation section 9.
Further, since the crushing device 21 crushes the floating sludge that flows in a fixed amount at a time, it can be easily crushed to a constant particle size, thereby recovering the sedimentation property of the sludge and performing an efficient anaerobic treatment. . The buoyant sludge floating on the gas collecting part 10 is easily circulated to the reaction part 11 by stirring due to the release of gas, and finally flows into the solid-liquid separation part 9 from the communication passage 12 and is taken out from the floating sludge unloading part 14. Gas collection part 1
The floating sludge extraction unit 14 may be provided at 0.

[0034]

As described above, according to the present invention, the floating sludge take-out portion is provided near the upper portion of the communication passage of the anaerobic reaction tank and the solid-liquid separation portion, and is located at a position away from the upper portion of the communication passage. Since the treatment liquid take-out section is provided and the baffle is provided between the two, the floating sludge is efficiently taken out and crushed, the sedimentation property is restored and returned to the reaction section, thereby preventing the sludge from flowing out and at the same time sludge in the tank. Anaerobic treatment can be efficiently performed by increasing the concentration.

[Brief description of drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anaerobic reaction tank 2 Treatment liquid inflow part 3 Treatment 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 Floating sludge take-out part 15 Floating sludge take-out route 16 Treated liquid take-out part 17 Treated liquid take-out route 18 Baffle 21 Crushing device 22 Pressure equalizing pipe 23 Crushing pump 24 Sludge return route

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Nakayama 3-4-7 Nishishinjuku, Shinjuku-ku, Tokyo Kurita Industry Co., Ltd.

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 arranged so as to be inclined so as to separate the solid-liquid separation part and the gas collection part, a communication path that connects the lower part of the solid-liquid separation part and the reaction part, and a solid part near the upper part of the communication path. An overflow-type floating sludge take-out unit provided in the liquid separation unit, an overflow-type treatment liquid take-out unit provided in the solid-liquid separation unit at a position apart from the upper portion of the communication passage, the treatment liquid take-out unit, and a floatation unit. An anaerobic treatment characterized by comprising a baffle provided near the liquid surface between the sludge taking-out parts and a crushing device for crushing the granular sludge taken out from the floating sludge taking-out part and returning it to the reaction part. apparatus.