JP2001137889A - Method and device for anaerobic treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anaerobic treating method and device capable of efficiently executing an anaerobic treatment by propagating granule sludge even in the case of the treatment under conditions under which the granule sludge is liable to decay. SOLUTION: In the method for executing the anaerobic treatment by passing liquid 4 to be treated in upward stream in a reaction chamber 1 and bringing this liquid into contact with a blanket 14 of the granule sludge, the anaerobic treatment is executed by injecting a flocculating agent 19 into the chamber 1 from a flocculating agent tank 17 when the granule sludge is liable to be destroyed, for example, when the liquid to be treated is low in the base concentration of acid forming bacteria.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for anaerobic treatment by bringing a liquid to be treated into contact with granulated sludge, and particularly to an anaerobic treatment method and apparatus suitable for anaerobic treatment under conditions in which granulated sludge is likely to collapse. It is about.

[0002]

2. Description of the Related Art As an anaerobic treatment method for organic wastewater, a high-density, large sedimentable granular sludge is formed, and an organic wastewater containing soluble BOD is circulated upward to form a sludge blanket. UASB (Upflow Anaerobic) that performs high-load, high-speed processing by contacting the formed state
Sludge Blanket: Upflow anaerobic sludge blanket) is employed. This method is a method of separating solid organic substances having a low digestion rate and separately treating them, and treating only soluble organic substances having a high digestion rate at a high load by anaerobic treatment using granule sludge having a high anaerobic microorganism density. It is. In addition, as a development of this UASB, liquid is passed at a higher flow rate using a high reaction tank, and a sludge blanket is developed at a high development rate.
EGSB (Expan) that performs anaerobic treatment at higher load
deed Granule Sludge Blanke
t) is also performed.

[0003] Anaerobic treatment using granulated sludge such as UASB and EGSB is a method of treating and maintaining sludge containing anaerobic microorganisms in the form of granules. This method can achieve a high sludge retention concentration compared to a fixed bed or a fluidized bed that holds sludge on a carrier, enabling high-load operation.In addition, by procuring surplus sludge from a treatment system that is already operating, short-term operation is possible. And is generally recognized as the most efficient anaerobic treatment method. The most important point of this method is to maintain and proliferate the granular sludge. If this is not possible, the treatment performance will gradually decrease, and the treatment will eventually become impossible. Such granule sludge can be spontaneously formed by passing an ordinary organic wastewater in an upward flow to perform anaerobic treatment.

[0004] Granular sludge in usual UASB, EGSB, etc. is acetic acid-utilizable Methanosaeta.
The microorganisms of the genus form a skeleton, and hydrogen-assimilating methane bacteria, acetic acid-producing bacteria, and acid-producing bacteria coexist, forming a kind of ecosystem. In addition, acid-producing bacteria that degrade carbohydrates, lipids, proteins, etc., produce mucilage and work to strengthen the binding force between bacteria, and when sugar substrates are used, the strongest granular sludge is formed. Is done. Normal sewage and other organic wastewater contain saccharides and other high-molecular organic substances, and when they are anaerobically treated, the above-mentioned microorganisms generate organic acids, which are successively reduced in molecular weight to acetic acid. Is further decomposed into methane and carbon dioxide. For this reason, the above-mentioned various microorganisms proliferate, and granular sludge with high strength is formed.

However, unlike such ordinary organic wastewater, when a liquid to be treated having a low substrate concentration of acid-producing bacteria, for example, a liquid to be treated containing a lower organic substance having 4 or less carbon atoms discharged from a chemical factory or the like, is treated. Granule sludge is likely to collapse. In particular, an organic substance having 2 or less carbon atoms such as acetic acid, ethanol, acetaldehyde or the like as a main component (90% by weight of all organic substances)
Meth)
The genus anosaeta becomes the main microorganism, and the production of sticky substances is reduced. Therefore, the growth of granular sludge is not good, and the strength is insufficient. Therefore, if the operation is continued for a long period of time, the granular sludge will be dismantled and reduced in particle size, and the amount of sludge will decrease. In particular, when a substrate having 1 carbon atom, that is, methanol, formic acid, formaldehyde, or the like is a main component, the above-mentioned genus Methanosaeta cannot assimilate these substrates.
It becomes a situation in which methane bacteria of the genus rcina or Methanobacterium grow and grow more difficult to granulate. For example, if the operation of the UASB is continued for a long time using methanol as a single substrate, the granules are dismantled, miniaturized, and the amount of sludge drastically decreases. For this reason, it has been difficult to perform anaerobic treatment of the liquid to be treated mainly containing a low-molecular organic substance as described above using granule sludge.

[0006] By the way, at the start of anaerobic treatment using granular sludge such as UASB, there is known a method of promoting the formation of granular sludge by adding a flocculant to dispersed sludge (for example, Japanese Patent Application Laid-Open No. Hei 4 (1994)). −3269
No. 95). This method aims at promoting granulation by coagulating sludge present in a dispersed state with a coagulant, and starting up anaerobic treatment using granule sludge at an early stage. However, the granular sludge formed by this method has a granular-like shape in order to agglomerate the dispersed sludge, but is not dense because the water is embraced in the sludge during the granulation process using a flocculant. Accordingly, there is a problem that air bubbles accumulate in a water portion and sludge is reduced in weight and floats. Therefore, in this method, anaerobic treatment using granular sludge can be started up at an early stage, but it is difficult to perform stable operation for a long period of time without disintegrating the granular sludge.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for treating granulated sludge under conditions in which the sludge tends to collapse.
An object of the present invention is to propose an anaerobic treatment method and apparatus capable of efficiently performing anaerobic treatment by growing granule sludge.

[0008]

The present invention relates to the following anaerobic treatment method and apparatus. (1) In a method in which a liquid to be treated is introduced into a reaction tank holding granule sludge and brought into contact with the granular sludge to perform anaerobic treatment, the liquid to be treated is added while adding a flocculant to the reaction tank after startup. An anaerobic treatment method characterized by performing anaerobic treatment by contacting with granular sludge. (2) The method according to the above (1), wherein the liquid to be treated mainly contains an organic substance having 4 or less carbon atoms. (3) The method according to the above (1) or (2), wherein the liquid to be treated contains at least one of a chelating agent, a scale dispersant, and a bactericide. (4) The method according to any one of the above (1) to (3), wherein the coagulant is a polymer coagulant. (5) A reaction tank that holds granule sludge and performs anaerobic treatment by bringing it into contact with the liquid to be treated, a liquid supply path that introduces the liquid to be treated into the reaction tank, and a coagulant that injects a coagulant into the liquid to be treated. An anaerobic treatment apparatus including an injection passage and a treatment liquid passage for discharging a treatment liquid from a reaction tank.

The liquid to be treated in the present invention may be a liquid containing an organic substance which can be treated by anaerobic treatment by bringing it into contact with granule sludge. It is suitable for treating liquids that are easily broken. Examples of the liquid to be treated in which granule sludge is liable to disintegrate include a liquid containing an organic substance having a low substrate content of an acid-producing bacterium composed of an organic substance having 5 or more carbon atoms such as carbohydrates, fats, and proteins. Those having a content of not more than 30% by weight, particularly not more than 20% by weight of the whole organic matter are mentioned. Specifically, a liquid to be treated mainly containing a lower organic substance (for example, 70% by weight or more, particularly 80% by weight or more of the whole organic substance) is exemplified. Here, examples of the lower organic substances include organic substances having 4 or less carbon atoms, particularly 2 or less carbon atoms. Granular sludge is apt to be disintegrated as the amount of organic substances having a small carbon number is increased.

In addition, the substrate of the acid-producing bacterium is sufficiently contained in the liquid to be treated.
Even if it is present in the liquid to be treated,
If a scale dispersant, disinfectant, etc.
In such a case, the Nile sludge is likely to collapse.
The method of the present invention may be applied to the method. In particular, EDTA
Range amine tetraacetic acid) and NTA (nitrile triacetic acid)
The chelating agent is contained in the liquid to be treated at a concentration of 3 mg / l or more.
In such cases, granule sludge tends to collapse. Another kill
Granules are especially useful as a fungicide for dithiocarbamate
It tends to break up sludge. In addition, the liquid to be treated
Has no cause to disrupt granulated sludge,
Granular sludge can easily break down depending on the treatment conditions
May be. Such cases include, for example, sludge
Examples include a case where the load is high and a case where the liquid passing speed is high.
For example, in the case of UASB, the sludge load is 0.6 kg-
COD_cr/ Kg-VSS / d or
When the liquid velocity exceeds 1 m / h, sludge is used for EGSB.
Load is 0.7kg-COD _cr/ Kg-VSS / d, liquid flow
When the speed exceeds 5m / h, the liquid to be treated
Granule sludge is easy to collapse even if there is no problem in itself
Therefore, according to the present invention, by adding a flocculant to the liquid to be treated
Prevent granule sludge from collapsing.

The granule sludge in the present invention is sludge in which sludge containing anaerobic microorganisms is granulated by the self-granulating action of the microorganisms to form sedimentable granules. UA
Although the growth process of granular sludge in the SB method is not clear, anaerobic microorganisms adhere to the surface of minute inorganic SS with a particle size of about 0.1 mm and the surface of scale components containing calcium and magnesium, New anaerobic microorganisms grow and adhere in the form of annual rings with the tiny SS and scale as nuclei.
It is said to grow into granular sludge of mm. It is said that the grown granular sludge is crushed by a flow caused by the flow of water or gas in the reaction tank, and the crushed fine particles and debris become nuclei to grow the next granular sludge.

As described above, such granular sludge grows without disintegration when anaerobic treatment is applied to ordinary organic wastewater such as beer wastewater or beet sugar production wastewater. The anaerobic treatment of the treatment liquid, particularly the liquid to be treated mainly containing a lower organic substance, the case where the treatment liquid contains a chelating agent or the like, and the condition of the anaerobic treatment facilitates the disintegration. Here, the disintegration of the granular sludge means a phenomenon in which the formed granular sludge disintegrates with the continuation of the anaerobic treatment.

[0013] As described above, granule sludge in ordinary UASB, EGSB, etc., is acetic acid-utilizing Methanan.
A microorganism of the genus osaeta forms a skeleton, and hydrogen assimilating methane bacteria, acetic acid producing bacteria, acid producing bacteria, and the like coexist. Of these, acid-producing bacteria that degrade carbohydrates, lipids, proteins, etc., produce slime, which acts as a binder to strengthen the binding force between bacteria to form granular sludge. Therefore, when there is no acid-producing bacterium that decomposes these substrates, it becomes difficult to produce a mucilage, and the granular sludge will collapse. Such a system in which no acid-producing bacteria are present is a system in which a substrate of acid-producing bacteria does not exist.
In an anaerobic treatment of a liquid to be treated having a weight percentage of not more than 20% by weight, in particular, the amount of acid-producing bacteria is reduced, and the granular sludge is easily disintegrated. For this reason, in the anaerobic treatment of the liquid to be treated containing a lower organic substance as a main component, ordinary granular sludge gradually collapses. Further, when the liquid to be treated contains a chelating agent or the like, or when the sludge load or the liquid passing rate is high, the binding strength of the granules tends to be weak even when a large number of acid-producing bacteria are present.

According to the present invention, the granule sludge is subjected to anaerobic treatment by bringing the liquid to be treated into contact with the granule sludge while adding a coagulant to the reaction tank during the treatment under the condition in which the granule sludge is likely to collapse. Prevents sludge collapse and proliferates granular sludge in the reaction tank to efficiently perform anaerobic treatment. The coagulant to be added may be any as long as it can prevent the disintegration of the granular sludge. However, the use of a polymer coagulant is preferable because the microorganisms can be held in the granules at a high density with a small amount of addition.

As the coagulant, nonionic, cationic,
Those suitable for the treatment system such as an anionic system and an amphoteric system can be used. Preferred polymer flocculants include the following. Nonionic: polyacrylamide, polyethylene oxide, etc. Cationic: polyaminoalkyl methacrylate, polyethyleneimine, polydiallylammonium halide, chitosan, urea-formalin resin and the like. Anionic: sodium polyacrylate, polyacrylamide partial hydrolyzate, partially sulfomethylated polyacrylamide, poly (2-acrylamide) -2-methylpropane sulfate, and the like. Amphoteric: Copolymer of acrylamide, aminoalkyl methacrylate and sodium acrylate.

In the treatment apparatus of the present invention, a supply liquid for introducing a treatment liquid and a treatment liquid passage for discharging the treatment liquid are connected to a reaction tank for holding the granular sludge, and a coagulant is injected into the treatment liquid. A coagulant injection path is provided. The reaction tank is structured to contact the liquid to be treated with the granular sludge.
It is preferable to form a sludge blanket such as EGSB in which the liquid passage to be treated is connected to the lower part of the reaction tank and the treatment liquid path is connected to the upper part of the reaction tank, and the liquid is passed in an upward flow to spread the granulated sludge. In this case, a gas-liquid-solid separation device can be provided at the upper part of the reaction tank, and the gas extraction path can be connected to the top.

In the treatment of the present invention, anaerobic treatment is performed by holding granular sludge in a reaction tank, introducing a liquid to be treated while adding a coagulant to the reaction tank, and bringing the liquid into contact with the granular sludge. Granular sludge may be formed spontaneously by subjecting the liquid to be treated to anaerobic treatment. However, since it takes time to form, granular sludge discharged as surplus sludge from existing UASB and EGSB facilities is used. When used, processing can be started up in a short time.

The method of treatment is as follows. When the liquid to be treated is passed in an upward flow like UASB and EGSB to develop the granular sludge and form a sludge blanket, the contact efficiency between the liquid to be treated and the granular sludge is reduced. It is preferable because it becomes high.
In the case of UASB, the average particle size of granulated sludge is 0.5-3.
mm, preferably 0.8-1.5 mm, and the sludge load is 0.3 mm.
1-1 kg-COD _cr / kg-VSS / d, preferably 0.2-0.6 kg-COD _cr / kg-VSS / d, upward flow rate of the liquid to be treated 0.3-1.5 m / hr, preferably It can be 0.5 to 1.0 m / hr. EGSB
In the case of granule sludge average particle size 0.8-3mm,
Preferably 1-1.5 mm, sludge load 0.1-1 kg
-COD _cr / kg-VSS / d, preferably 0.2 to
0.7 kg-COD _cr / kg-VSS / d, the upward flow velocity of the liquid to be treated is 3 to 10 m / hr, preferably 2 to 5 m / hr.

The liquid to be treated is an organic substance concentration of COD.
_Cr 500 to 30,000 mg / l, preferably 1000
It is suitable to process up to 20,000 mg / l. The load can be 5 to 30 kg-COD _cr / m ³ / d, preferably 8 to 20 kg-COD _cr / m ³ / d, and the temperature in the reaction vessel can be 25 to 40 ° C., preferably 30 to 38 ° C. .

The coagulant is preferably added to the liquid to be treated and brought into contact with the granular sludge in a uniformly dissolved state, so that the coagulant can be uniformly contacted with the granular sludge at a concentration suitable for coagulation. When a pH adjusting tank is provided before the reaction tank, it may be added to the pH adjusting tank. The addition concentration of the flocculant is 0.1 to 2 mg / l in the case of the polymer flocculant,
Preferably, it is about 0.1 to 1 mg / l. The coagulant is added continuously or intermittently after the start of the reaction tank.

The solution to be treated having a low acid-producing bacterium concentration is UA
When the anaerobic treatment is performed using SB, EGSB, or the like, the acid-producing bacteria do not proliferate, so that the production of mucilage is reduced, and the granular sludge has low strength and is easily disintegrated. Especially carbon number 4
In the case of treating the water to be treated mainly containing the following lower organic substances, the granules are of the genus Methanosaricina, which assimilates acetic acid, methanol, methylamine, etc.
ethanosaeta genus (= Methanothri
(genus x). Since these bacteria hardly form granules, it is necessary to increase the granule strength. Also, when a chelating agent or the like is contained in the liquid to be treated, or when the sludge load or the liquid passing speed is large, the granules are easily disintegrated. When a flocculant is added to such a system, the flocculant binds the suspended cells to the granular sludge, increases the strength and grows the granules,
Granule sludge multiplies.

As described above, the flocculant acts as a binder similarly to the mucilage produced by the acid-producing bacterium, and thereby retains the granule sludge even in a system in which the granule is easily disintegrated because the mucilage is small. Propagation can increase the efficiency of anaerobic treatment. JP-A-4-3
In the method of adding a flocculant at the start of treatment as in No. 26995, the dispersed sludge is flocculated with the flocculant, so that it is not possible to generate dense granular sludge by embracing water. This is not the case because the granulated sludge is used, and the dense and strong granulated sludge is maintained and formed. When the addition amount of the coagulant increases, the biogas generated by the anaerobic treatment is taken into the granules and lightened.
It is preferable to add at a concentration that does not take in biogas.

[0023]

According to the present invention, the anaerobic treatment is performed while adding the coagulant to the reaction tank after the start of the anaerobic treatment using the granular sludge, so that the granular sludge is easily disintegrated. Even in the case of the treatment under the condition, the anaerobic treatment can be efficiently performed by growing the granular sludge.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a UASB type anaerobic treatment device of the embodiment. In FIG. 1, reference numeral 1 denotes a reaction tank, which is formed of a rectangular parallelepiped container, has a processing liquid inflow portion 2 provided uniformly at the bottom thereof, and has a processing liquid passage 4 having a pump 3.
Contact The upper part of the anaerobic reaction tank 1 is covered with a cover 5 to form a gas chamber 6 having a closed structure, and a gas transfer path 7 communicates with the top.

A liquid chamber 8 is formed below the gas chamber 6 in the reaction tank 1, and a solid-gas separation member comprising first and second partition plates inclined in opposite directions is formed above the liquid chamber 8. 9a and 9b are arranged, and a solid-liquid separation unit 10 is defined inside the upper part, a gas collection part 11 is defined outside the upper part, and a reaction part 12 is defined below. The lower ends of the solid-gas separation members 9a and 9b are separated to form a communication path 13, and one lower end covers the lower side of the other lower end. It is designed to prevent entry.

The liquid to be treated is introduced into the liquid chamber 8 in the reaction tank 1, and a sludge blanket 14 is formed in the reaction section 12. Above the solid-liquid separation unit 10, an overflow type processing liquid take-out unit 15 is provided.
Contact Reference numeral 17 denotes a coagulant tank, and a coagulant injection path 19 having a valve 18 is connected to the liquid passage 4 from below. Reference numeral 20 denotes a gas holder, which communicates so as to introduce generated gas from the gas transfer path 7 and take it out from the gas extraction path 21.

In the anaerobic treatment method using the above-described anaerobic treatment apparatus, first, granular sludge containing anaerobic microorganisms granulated by utilizing the self-granulating property of anaerobic microorganisms is charged into the reaction section 12 of the reaction tank 1. I do. Then, the pump 3 is driven, and the liquid to be treated is introduced from the liquid passage 4 to be treated into the liquid inflow section 2 provided at the bottom of the reaction tank 1, and the sludge blanket 14 is formed by flowing the liquid upward. Anaerobic reaction by contact under anaerobic condition. Thereby, the soluble organic matter in the liquid to be treated is decomposed into methane and carbon dioxide by the action of the anaerobic microorganism.

Since the granular sludge has a high density and an excellent sedimentation property, a uniform sludge blanket 14 is formed by passing the wastewater in an upward flow, and the sludge blanket 14 is held in the reaction section 12. The organic effluent that has passed through the sludge blanket 14 enters the solid-liquid separation unit 10 through the communication path 13, where it is separated into solid and liquid. The separated liquid overflows from the processing liquid extraction unit 15 and flows into the processing liquid path 16 as a processing liquid. Be taken out.
The sludge separated in the solid-liquid separation section 10 is settled, and the
Then, the process returns to the reaction section 12. Gas such as methane generated in the reaction section 12 rises in the reaction section 12, but the gas-solid separation member 9a,
9b, the gas does not flow into the solid-liquid separation unit 10, but is collected in the gas collection unit 11, transferred from the gas chamber 6 to the gas holder 20 via the gas transfer path 7, stored and taken out from the gas extraction path 21. It is.

In the above-mentioned treatment, for example, when a liquid to be treated having a low substrate content of an acid-producing bacterium is treated as a liquid to be treated, the growth of the acid-producing bacterium does not proceed, and the production of exudates is reduced. Lower and easier to decompose. Then, the valve 18 is opened, the coagulant is continuously or intermittently injected into the liquid to be treated from the coagulant tank 17 through the coagulant injection path 19, and is introduced into the reaction tank 1 in a mixed state.

The coagulant binds the anaerobic microorganisms to the granular sludge while the liquid to be treated flows upward, and acts as a binder. Therefore, the granular sludge is given strength and the anaerobic microorganisms are granulated. Proliferate in annual rings on the sludge. Thereby, granular sludge with high density and high strength is obtained, and the anaerobic treatment is continuously performed efficiently.

[0031]

Embodiments of the present invention will be described below. Example 1, Comparative Example 1 Acetic acid of 2,000 mg / l, yeast extract of 20 mg / l
Synthetic wastewater (N = 20 mg / l, P = 4 mg / l with NH
₄ Cl, added with KH ₂ PO ₄ ) as a liquid to be treated, a small UA having an inner diameter of 10 cm, a height of about 120 cm, and a capacity of 9 liter.
The anaerobic treatment was performed by passing water through the SB reaction tank, and the granular sludge was grown, and the average particle size was tracked over a period of 4 months. In the system A of Comparative Example 1, a coagulant was not added, and in the system B of the example, a polyaminoalkyl acrylate-based cationic polymer was added as a coagulant to the liquid to be treated at a concentration of 0.5 mg / l. Granule sludge is used for wastewater treatment in beer factories.
It was collected from ASB and had an average particle size of 1.4 mm. Water flow conditions are organic substance load 15-18 kg-COD _cr
/ M ₃ / day, sludge load 0.4-0.5 kg-COD
_cr / kg-VSS / d, rising velocity 3 m / hr, temperature 35
C, pH is 6.8-7.5. Sludge outflow was small in both the A and B systems, and the COD _cr removal rate in both the treatment and the loading system was smoothly performed at about 95%. In the case of the system B of Example 1, the sludge interface continuously and stably increased, and sludge multiplication was confirmed. On the other hand, in the system A of Comparative Example 1, almost no increase in the sludge interface was observed, and no sludge multiplication was observed. The average particle size of the A-type granule sludge stayed inside and outside 1.3 mm, and the growth per granule was small. FIG. 2A shows a change in the sludge interface height, and FIG. 2B shows a change in the average particle size of the granular sludge.

Example 2, Comparative Example 2 In the same apparatus as in Example 1, water was passed instead of acetic acid and methanol (2,000 mg / l of methanol, and other substrate conditions were the same as in Example). Load is 15-18kg
−COD _cr / m ³ / day. The treatment was stable in both systems until about the 100th day. However, after 110 days, the outflow of the sludge of the A system of Comparative Example 2 became remarkable, and the treated water deteriorated.
The COD _cr removal rate of the A system decreased from 95% to about 80%. On the other hand, in the system B of Example 2, the treatment was stable, and the COD _cr removal rate was continuously maintained at 95%. In the A system, sludge runoff on the 110th day was due to sludge dismantling, which is supported by the decrease in average particle size. Since the particle diameter of the B-series sludge also tends to increase and the sludge interface has risen steadily, it is clear that the sludge multiplication has been stably maintained. FIG. 3A shows a change in sludge interface height, and FIG. 3B shows a change in average particle size of the granular sludge.

From the above results, when the liquid to be treated having a low substrate content of acid-producing bacteria and mainly containing lower organic substances is treated,
Granular sludge is easily disintegrated, but when such a liquid to be treated is treated, it can be seen that granule sludge can be retained and multiplied by adding a coagulant.

[Brief description of the drawings]

FIG. 1 is a flowchart of an anaerobic treatment device of an embodiment.

FIGS. 2A and 2B are graphs showing the results of Example 1 and Comparative Example 1. FIGS.

FIGS. 3A and 3B are graphs showing the results of Example 2 and Comparative Example 2. FIGS.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reaction tank 2 liquid to be treated 3 pump 4 liquid to be treated 5 cover 6 gas chamber 7 gas transfer path 8 liquid chamber 9 a, 9 b solid-gas separation member 10 solid-liquid separation unit 11 gas collection unit 12 reaction unit 13 communication path 14 Sludge blanket 15 Processing liquid outlet 16 Processing liquid path 17 Coagulant tank 18 Valve 19 Coagulant injection path 20 Gas holder 21 Gas extraction path

Claims (5)

[Claims] 1. A reactor for holding granulated sludge,
In the method of introducing the liquid to be treated and bringing it into contact with the granular sludge for anaerobic treatment, the anaerobic treatment is carried out by bringing the liquid to be treated into contact with the granular sludge while adding a flocculant to the reactor after startup. An anaerobic treatment method characterized by the following. 2. The method according to claim 1, wherein the liquid to be treated mainly contains an organic substance having 4 or less carbon atoms. 3. The method according to claim 1, wherein the liquid to be treated contains at least one of a chelating agent, a scale dispersant, and a bactericide. 4. The method according to claim 1, wherein the flocculant is a polymer flocculant. 5. A reactor for holding anaerobic treatment by holding granule sludge and contacting it with a liquid to be treated, a liquid supply passage for introducing the liquid to be treated into the reaction tank, and injecting a flocculant into the liquid to be treated. An anaerobic treatment apparatus including a coagulant injection passage and a treatment liquid passage for discharging a treatment liquid from a reaction tank.