CN109219580B

CN109219580B - Sludge treatment device and sludge treatment method

Info

Publication number: CN109219580B
Application number: CN201780032712.3A
Authority: CN
Inventors: 黑木洋志; 平敷勇; 有马芳明; 古川诚司; 时盛孝一; 小原慎太郎; 大泉雅伸; 若村修; 臼井肇
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-06-08
Filing date: 2017-06-01
Publication date: 2020-12-22
Anticipated expiration: 2037-06-01
Also published as: WO2017213024A1; JP6334833B2; JPWO2017213024A1; CN109219580A; SG11201809834QA

Abstract

A sludge treatment device (100) is provided with: an ozone reaction tank (10) to which a sludge-containing liquid (X) is supplied and into which ozone gas (Q) is injected to generate bubble sludge (A1); and an addition tank (20) which is provided at the subsequent stage of the ozone reaction tank (10), and which adds a1 st flocculant (G1) to the foam sludge (A1) supplied from the ozone reaction tank (10), mixes the treated water (Z) to produce a mixed sludge solution (B), and coagulates the sludge solubilized by the ozone gas (Q) to produce a coagulated sludge having a large amount of organic matter.

Description

Sludge treatment device and sludge treatment method

Technical Field

The present invention relates to a sludge treatment apparatus and a sludge treatment method used for sludge treatment, and particularly to treatment of sludge solubilized (solubilized) by ozone gas.

Background

Conventionally, as a method for treating sewage, food wastewater, livestock wastewater, and the like containing organic sludge substances, an activated sludge method using microorganisms called activated sludge has been widely used. In the activated sludge process, a large amount of sludge containing microorganisms, called excess sludge, is produced during the treatment process. Therefore, the large amount of excess sludge is reduced in volume and then disposed of in landfills or incinerated.

In recent years, the excess sludge has been used as a fuel source to effectively utilize the excess sludge. In particular, the following should be done: methane gas is generated by anaerobic digestion of the generated excess sludge, and thermal energy and electric energy are recovered by burning the methane gas or utilizing the methane gas for gas power generation.

In order to increase the amount of energy recovered from excess sludge by anaerobic digestion treatment, it is necessary to increase the amount of methane gas generated. Therefore, the following method is used: methane gas is efficiently produced by subjecting excess sludge to anaerobic digestion treatment after the excess sludge is solubilized by a physical or chemical method. As conventional methods for solubilizing physical sludge, there are decomposition of organic substances using ozone gas, reduction of molecular weight using ultrasonic waves, and the like. As a method for solubilizing chemical sludge, there is a method of solubilizing sludge by acid, alkali, enzyme, or the like.

In the case of anaerobic digestion treatment of excess sludge, it is necessary to reduce the volume of excess sludge by previously concentrating the excess sludge in order to improve the treatment efficiency. This is because the anaerobic digestion treatment requires a retention time of about 20 days to 50 days, and therefore, if the anaerobic digestion treatment is performed without reducing the volume of the excess sludge, a large-sized anaerobic digestion treatment tank is required. As the concentration treatment for concentrating and reducing the volume of the excess sludge, a floating separation method, a coagulation sedimentation method, or the like is used.

Accordingly, the following sludge treatment apparatus and sludge treatment method are disclosed in which excess sludge is solubilized with ozone gas and the volume of the excess sludge is reduced.

Organic waste liquid such as sewage is once accumulated in a storage tank, then introduced into an aeration tank, and aerobically brought into contact with activated sludge in the aeration tank to perform aerobic biological treatment. And carrying out solid-liquid separation on the treatment liquid in a settling tank to obtain treatment water and excess sludge. The clear treated water is subjected to water quality adjustment in a water quality adjustment tank and discharged to the outside of the treatment system. Excess sludge is returned as a source of aerobic microorganisms to an aeration tank through a return path, and the other part is concentrated by a concentration device such as a centrifugal separator. Subsequently, the concentrated excess sludge after the concentration treatment is transferred to an ozone treatment tank to be subjected to ozone treatment. Ozone generated in the ozone generator is introduced into the ozone treatment tank to perform a solubilization treatment for concentrating excess sludge. Next, excess sludge solubilized in the ozone treatment tank is transferred to an anaerobic digestion treatment apparatus without being returned to the aerobic biological treatment, and is subjected to anaerobic digestion treatment, and the generated gas is recovered and recovered, thereby stabilizing and reducing the volume of the excess sludge (see, for example, patent document 1).

In order to reduce the volume of excess sludge in the final sedimentation tank of the sewage treatment plant, an excess sludge pipe is connected to the ozone treatment apparatus. The bubble recovery device is connected to the rear stage of the ozone treatment device via a sludge pipe. A bubble recovery pipe for connecting the chemical liquid supply device to the bubble recovery device. A sludge concentration treatment apparatus is connected to a rear stage of a chemical liquid supply apparatus via a chemical liquid treatment sludge pipe, and a concentrated sludge pipe is disposed in the sludge concentration treatment apparatus. The concentrated sludge pipe is connected to a phosphorus recovery processing device. The phosphorus recovery processing device is connected to a digestion processing device provided with a digested sludge pipe through a phosphorus removal sludge pipe.

If the bubbles (sludge) collected from the bubble recovery pipe are concentrated in the latter stage of the ozone treatment apparatus, the phosphorus recovery rate and the amount of generated digestion gas increase, and the amount of generated sludge can be reduced (see, for example, patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2002-1398 (paragraphs [0019] to [0021], FIG. 1)

Patent document 2: international publication No. WO2015/166784A1 (paragraphs [0011], [0016], FIG. 1)

Disclosure of Invention

Problems to be solved by the invention

In the conventional sludge treatment apparatus and sludge treatment method of patent document 1, excess sludge is concentrated before being transferred to the ozone treatment tank. The concentration of the solid matter of the excess sludge thus concentrated is in the range of 20g/L to 50 g/L. Since the excess sludge thus concentrated does not have fluidity, if ozone gas is injected, it is difficult to uniformly mix the ozone gas with the excess sludge. Thus, the ozone gas forms a gas reservoir in the concentrated excess sludge. Thereafter, the injected ozone gas is collected in the gas reservoir, and the volume of the gas reservoir increases.

If a gap is formed between the gas reservoir and the surface of the concentrated excess sludge, where gas leaks to the outside of the sludge, the gas flows out from the gas reservoir to the outside of the concentrated sludge. In such a large-volume gas reservoir, the contact efficiency between the concentrated excess sludge and the ozone gas is deteriorated, and therefore, a large amount of unreacted ozone gas is contained in the gas released from the gas reservoir. By stirring the concentrated surplus sludge, the contact efficiency between the ozone gas and the concentrated surplus sludge in the gas reservoir can be improved. However, the gas pool reaches the surface of the thickened surplus sludge by the agitation, and the possibility that the ozone gas in the gas pool escapes from the surface of the thickened surplus sludge is increased. Therefore, if ozone gas is injected into the concentrated excess sludge, unreacted ozone gas is generated, and therefore, there is a problem that the amount of ozone gas required for solubilizing the concentrated sludge increases, resulting in an increase in cost.

In addition, in the conventional sludge treatment apparatus and sludge treatment method of patent document 2, concentration treatment for reducing the volume of the excess sludge solubilized by ozone treatment is performed on the excess sludge having a high concentration. The flocculant used in such a concentration treatment is a highly viscous polymer flocculant. Therefore, if such a polymer flocculant is added to the high-concentration excess sludge solubilized by ozone treatment, the flocculant does not diffuse in the excess sludge, and the concentration efficiency is lowered. Therefore, a large amount of sludge remains in the water separated from the excess sludge, and the amount of organic matter in the concentrated excess sludge decreases.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a sludge treatment apparatus and a sludge treatment method that reduce the amount of ozone gas used and increase the amount of organic matter in flocculated sludge.

Means for solving the problems

The sludge treatment apparatus according to the present invention comprises: a1 st treatment unit to which a sludge-containing liquid is supplied and into which ozone gas is injected to generate a1 st sludge; and a2 nd treatment unit which is provided at a subsequent stage of the 1 st treatment unit, adds a1 st flocculant to the 1 st sludge supplied from the 1 st treatment unit, and mixes the 1 st sludge with treatment water to produce a2 nd sludge.

Further, a sludge treatment method according to the present invention includes: an ozone reaction step of injecting ozone gas into a sludge retention liquid and foaming the sludge retention liquid to separate the sludge retention liquid into a bubble-like 1 st sludge and a residue liquid; and a1 st addition step of taking out the 1 st sludge separated, adding a1 st flocculant, and mixing the 1 st sludge with treated water to produce a2 nd sludge.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the sludge treatment apparatus and the sludge treatment method of the present invention, since the 1 st sludge produced by solubilizing the sludge retention liquid with the ozone gas is coagulated by mixing the 1 st coagulant and the treatment water, the amount of ozone gas used can be reduced and the amount of organic matter in the coagulated sludge can be increased.

Drawings

Fig. 1 is a schematic configuration diagram showing a sludge treatment apparatus according to embodiment 1 of the present invention.

Fig. 2 is a flowchart showing steps of a sludge treatment apparatus and a sludge treatment method according to embodiment 1 of the present invention.

Fig. 3 is a diagram illustrating a process of coagulating sludge using the sludge treatment apparatus and the sludge treatment method according to embodiment 1 of the present invention.

Fig. 4 is a diagram illustrating a process of coagulating sludge using the sludge treatment apparatus and the sludge treatment method according to embodiment 1 of the present invention.

Fig. 5 is a diagram illustrating a process of coagulating sludge using the sludge treatment apparatus and the sludge treatment method according to embodiment 1 of the present invention.

Fig. 6 is a diagram showing the contents of an experiment in which the aggregation effect of sludge was confirmed by using the sludge treatment apparatus and the sludge treatment method according to embodiment 1 of the present invention.

Fig. 7 is a graph showing the experimental results of confirming the sludge flocculation effect using the sludge treatment apparatus and the sludge treatment method according to embodiment 1 of the present invention.

Fig. 8 is a schematic configuration diagram showing a sludge treatment apparatus according to embodiment 2 of the present invention.

Fig. 9 is a schematic configuration diagram showing a sludge treatment apparatus according to embodiment 3 of the present invention.

FIG. 10 is a schematic configuration diagram showing a sludge treatment apparatus according to embodiment 4 of the present invention.

FIG. 11 is a schematic configuration diagram showing a sludge treatment apparatus according to embodiment 5 of the present invention.

FIG. 12 is a schematic configuration diagram showing each treatment system of a sludge treatment apparatus according to embodiment 5 of the present invention.

Fig. 13 is a view showing the amount of liquid of digested sludge Y treated by the dehydrator of the sludge treatment apparatus according to embodiment 5 of the present invention.

Detailed Description

Embodiment 1.

Hereinafter, a sludge treatment apparatus 100 and a sludge treatment method according to embodiment 1 of the present invention will be described with reference to the drawings.

Fig. 1 is a schematic configuration diagram showing a sludge treatment apparatus 100 according to embodiment 1 of the present invention.

Fig. 2 is a flowchart showing steps of an embodiment of the sludge treatment apparatus 100 and the sludge treatment method according to embodiment 1 of the present invention.

FIG. 3 is a view for explaining a process of aggregating sludge in the sludge-containing liquid X.

Fig. 4 is a diagram illustrating a process of the latter stage of fig. 3.

Fig. 5 is a diagram illustrating a process of the latter stage of fig. 4.

Fig. 6 is a diagram showing the contents of an experiment in which the sludge flocculation effect was confirmed by using the sludge treatment apparatus 100 and the sludge treatment method according to embodiment 1 of the present invention.

Fig. 7 is a graph showing experimental results in which the sludge flocculation effect was confirmed by using the sludge treatment apparatus 100 and the sludge treatment method according to embodiment 1 of the present invention.

As shown in fig. 1, a sludge treatment apparatus 100 according to embodiment 1 includes: an ozone reaction tank 10 as a1 st treatment part, and an addition tank 20 as a2 nd treatment part provided at a later stage of the ozone reaction tank 10.

The ozone reaction tank 10 is connected to the bubble generator 1, and is configured to inject fine bubbles of the ozone gas Q into the solution or the like stored in the ozone reaction tank 10 through the bubble generator 1.

As the bubble generator 1, for example, a gas diffusion tube provided with fine holes, a gas diffusion plate, an ejector, or the like can be used. Further, an outlet 2 is provided at an upper portion of the ozone reaction tank 10, and the flow path 3 communicates with the outlet 2. Further, an outlet 4 is provided at the lower part of the ozone reaction tank 10, and a flow path 5 is connected to the outlet 4.

The addition tank 20 includes: a separation tank 21 as a1 st tank connected to the flow path 3, and a mixing tank 22 as a2 nd tank provided at the subsequent stage thereof. The separation tank 21 and the mixing tank 22 are connected by a pipe 23. In addition, a mixing tank 22 is connected to the flow path 5.

The 1 st reservoir 25 for storing the 1 st flocculant G1 as an inorganic flocculant is connected to the separation tank 21, and the 1 st flocculant G1 is added to the solution or the like in the separation tank 21. The separation tank 21 is provided with a stirrer 24 as a defoaming unit.

A concentration tank 30 as a 3 rd treatment section is provided at the subsequent stage of the addition tank 20. The mixing tank 22 and the concentrating tank 30 are connected by a flow path 26. The 2 nd reservoir 35 for storing the 2 nd flocculant G2 as an organic flocculant is connected to the concentration tank 30, and the 2 nd flocculant G2 is added to the solution or the like in the concentration tank 30.

In the concentration tank 30, a floating separation apparatus, a coagulation sedimentation apparatus, or the like is used.

In the latter stage of the concentration tank 30, an anaerobic digestion tank 40 for performing anaerobic treatment by anaerobic microorganisms is provided. The concentration tank 30 and the anaerobic digestion tank 40 are connected by a flow path 31.

Hereinafter, the sludge flocculation step using the sludge treatment apparatus 100 configured as described above will be described with reference to fig. 1 and 2.

An aerobic treatment tank, not shown in fig. 1, for performing aerobic treatment by aerobic microorganisms is provided in the front stage of the sludge treatment apparatus 100. The sludge-containing liquid X containing excess sludge generated in the aerobic treatment tank is supplied to the ozone reaction tank 10 of the sludge treatment apparatus 100 of the present embodiment and stored in the ozone reaction tank 10.

Next, the accumulated sludge-containing liquid X is injected into the ozone reaction tank 10 into the fine bubbles of the ozone gas Q generated by the bubble generator 1. The injected ozone gas Q dissolves organic components contained in the sludge-containing liquid X. The ozone gas Q foams at the interface between the sludge-containing liquid X and the bubbles of the ozone gas Q, and bubble sludge a1, which is bubble-like 1 st sludge in which dissolved organic components, i.e., sludge, adhere to the bubble membranes, is generated on the top of the sludge-containing liquid X. By continuously supplying the sludge-containing liquid X and the ozone gas Q into the ozone reaction tank 10, bubble sludge a1 is repeatedly generated above the sludge-containing liquid X. Therefore, the newly generated bubble sludge a1 pushes up the previously generated bubble sludge a1 to the upper portion of the ozone reaction tank 10, and the bubble sludge a1 rises inside the ozone reaction tank 10 to fill the inside of the ozone reaction tank 10.

When the bubble sludge a1 rises in the ozone reaction tank 10, the ozone gas Q present inside the bubble sludge a1 continues to dissolve the sludge attached to the bubble film of the bubble sludge a 1. When the foam sludge a1 rising in the ozone reaction tank 10 reaches the upper part of the ozone reaction tank 10, it flows out from the outflow port 2 to the flow path 3.

Further, in the lower part of the ozone reaction tank 10, a residue liquid Z composed of moisture of the sludge-containing liquid X which does not adhere to the bubble sludge a1 is accumulated.

In this way, the ozone reaction tank 10 solubilizes the sludge in the sludge-containing liquid X with the ozone gas Q, thereby separating the sludge-containing liquid X into the bubble sludge a1 in which the solubilized sludge adheres to the bubbles and the residue liquid Z (ozone reaction step, step S1).

The foam sludge a1 thus extracted from the sludge-containing liquid X is transferred to the separation tank 21 of the addition tank 20 provided at the subsequent stage of the ozone reaction tank 10 through the flow path 3.

The separation tank 21 crushes the bubbles contained in the supplied foamed sludge a1 by the agitator 24 (defoaming step, step S2). In this way, the separation tank 21 breaks up the bubbles of the bubble sludge a1, thereby separating the bubble sludge a1 into the exhaust gas H containing the residual gas contained in the bubble sludge a1 and the sludge solution a2 which is the 1 st sludge containing the solubilized sludge.

Next, the 1 st flocculant G1, which is the inorganic flocculant stored in the 1 st storage section 25, is added to the sludge solution a2 in the separation tank 21.

In the separation tank 21, the 1 st flocculant G1 is uniformly mixed with the sludge solution a2, and therefore the 1 st flocculant G1 is added while the sludge solution a2 is stirred by the stirrer 24. The sludge solution a2 to which the 1 st flocculant G1 was added was drawn out from the separation tank 21 and transferred to the mixing tank 22 through the pipe 23.

Next, the mixing tank 22 mixes the residual liquid Z accumulated in the lower portion of the ozone reaction tank 10 with the sludge solution a2 as the treated water to generate a mixed sludge solution B as the 2 nd sludge.

In this way, the separation tank 21 and the mixing tank 22 of the addition tank 20 add the 1 st flocculant G1 to the sludge solution a2 and mix the residue liquid Z to produce a mixed sludge solution B (the 1 st addition step, step S3).

The mixed sludge solution B thus produced in the addition tank 20 is transferred to the concentration tank 30 as the 3 rd treatment unit provided at the subsequent stage of the addition tank 20 through the flow path 26.

Next, the 2 nd flocculant G2, which is an organic polymer flocculant stored in the 2 nd storage unit 35, is added to the mixed sludge solution B supplied from the addition tank 20 in the concentration tank 30 (the 2 nd addition step, step S4). The sludge component in the mixed sludge solution B is coagulated by the 2 nd coagulant G2 and separated into the concentrated sludge C as the 3 rd sludge and the separated liquid N. The separation liquid N is drained through the flow path 32.

The generated concentrated sludge C is transferred to an anaerobic digestion tank 40 provided at a later stage of the mixing tank 22 through a flow path 31.

Next, the anaerobic digestion tank 40 performs anaerobic treatment with anaerobic microorganisms on the supplied concentrated sludge C (digestion step, step S5). The concentrated sludge C is decomposed by anaerobic microorganisms to produce methane gas T.

In the above description, the addition tank 20 includes 2 tanks, i.e., the separation tank 21 and the mixing tank 22, but the present invention is not limited thereto. For example, the addition tank 20 may be provided with only 1 tank, and the addition of the 1 st flocculant G1 and the mixing of the residue liquid Z may be performed in the 1 tank. In this case, the residue liquid Z may be first mixed with the sludge solution a2 and then the 1 st flocculant G1 may be added, or the residue liquid Z and the 1 st flocculant G1 may be mixed simultaneously.

Next, a process of efficiently aggregating sludge in the sludge-containing liquid X by the sludge treatment apparatus 100 and the sludge treatment method according to the present embodiment will be described in detail with reference to fig. 3, 4, and 5.

The sludge and water contained in the sludge-containing liquid X shown in fig. 3(a) are separated into bubble sludge a1 (fig. 3(b)) and residue liquid Z (fig. 3(c)) by the ozone gas Q.

As shown in fig. 3(b), the sludge adhering to the bubble film of the bubble sludge a1 is solubilized by the ozone gas Q and becomes fine particles.

Since most of the sludge contained in the sludge-containing liquid X adheres to the bubble membrane of the bubble sludge a1, no sludge remains in the residual liquid Z. Since the water in the sludge-containing liquid X is separated as the residue liquid Z, the foam sludge a1 becomes a high-concentration solubilized sludge solution.

Next, as shown in fig. 3(d), the bubbles of the foamed sludge a1 are broken, whereby the sludge solution with bubble membranes formed therein is accumulated in the lower portion of the separation tank 21, and a high-concentration sludge solution a2 is produced.

Next, as shown in fig. 4(e), if the 1 st flocculant G1 is added to the sludge solution a2, the 1 st flocculant G1 is combined with the particles of the sludge solution a2 to produce aggregated particles R1.

The efficiency of producing the aggregated particles R1 depends on the probability of contact between the first aggregating agent G1 and the particles of the sludge in the sludge solution a2, and the sludge solubilized with the ozone gas Q has a particle diameter of 1 μm or less and is made into fine particles. Therefore, the use of the inorganic first flocculant G1 having a small molecule improves the contact efficiency.

As the inorganic first flocculant G1 for flocculating the sludge having been atomized, for example, polyferric sulfate, polyaluminum chloride, or the like can be used.

In addition, since the inorganic coagulant generally has a positive charge, it is electrically attracted to the fine particles having a negative charge on the surface thereof to form a large coagulation nucleus. The sludge particles made finer by the ozone gas Q as shown in the present embodiment have a negative charge on the surface, and therefore tend to attract each other with the inorganic flocculant having a positive charge. Therefore, the addition of the inorganic flocculant can efficiently flocculate the sludge atomized with the ozone gas Q.

Further, since the 1 st flocculant G1 is added to the sludge solution a2 in a state where bubbles of the bubble sludge a1 are broken, the contact efficiency of the sludge particles with the 1 st flocculant G1 is higher than that when sludge in a state where bubbles remain. By improving the efficiency of the formation of the aggregated particles R1 in this way, the amount of the first aggregating agent G1 used can be reduced.

Next, as shown in fig. 4(f), the sludge solution a2 to which the 1 st flocculant G1 is added is mixed with the residue liquid Z to produce a mixed sludge solution B. The sludge solution a2 was added with water via the residue liquid Z, whereby the distance between the agglomerated particles R1 in the sludge solution a2 was increased.

Next, as shown in fig. 5(G), a2 nd flocculant G2, which is an organic polymer flocculant having a large molecular structure, is added. The 2 nd flocculant G2 as a polymer flocculant has a very high viscosity, but is uniformly dispersed in the mixed sludge solution B having a viscosity lowered by adding water to the residue solution Z.

In this way, the distance between the aggregated particles R1 was increased in the mixed sludge solution B, and the 2 nd aggregating agent G2 was uniformly dispersed. Therefore, the binding efficiency of the 2 nd flocculant G2 to the aggregated particles R1 is improved. Thus, the 2 nd flocculant G2 and the agglomerated particles R1 were efficiently bonded to form larger agglomerated particles R2.

Next, as shown in fig. 5(h) and (i), the mixed sludge solution B is separated into a concentrated sludge C formed of the aggregated particles R2 and a separated liquid N as moisture in the mixed sludge solution B. Thus, a concentrated sludge C having a sludge component coagulated is obtained.

Thus, the 2 nd coagulant G2 effectively forms the coagulated particles R2. Thus, the sludge (organic matter) remaining in the separated liquid N and not coagulated by the 2 nd coagulant G2 is reduced to a small amount, and the concentrated sludge C having a large amount of organic matter is obtained.

The following description will be made of the results of the following experiment with reference to fig. 6 and 7: this experiment verifies that the sludge (the amount of organic matter) remaining in the separated liquid N discharged from the concentration tank 30 is reduced by using the sludge treatment apparatus 100 and the sludge treatment method of the present embodiment, that is, the efficiency of sludge recovery by the flocculant is improved.

The sludge flocculation property was evaluated by the organic matter concentration (TVS concentration) in the separated liquid N discharged from the thickening tank 30. The lower the concentration of organic matter contained in the separated liquid N, the better the recovery rate of sludge (organic matter) by the flocculant, and the larger the amount of organic matter in the concentrated sludge C.

In the experiment, ozone gas Q was injected into the sludge-containing liquid X so that the ozone absorption amount became 60mgO3/gSS, using the sludge-containing liquid X having a suspended matter concentration (SS concentration) of 5 g/L.

As the 1 st flocculant G1, iron polysulfate was used.

Further, as the 2 nd flocculant, a cationic powdery polymer flocculant MP-184 available from ハイモ was used. The polymer flocculant MP-184 was dissolved in water to prepare a 0.3 wt% solution, and the sludge was concentrated in the concentration tank 30.

In addition, in the addition step 2 in the concentration tank 30, the flocculated sludge is concentrated, and therefore, the sludge is separated into the concentrated sludge C and the separated liquid N by filtration using a 75 μm mesh.

Fig. 6 shows the coagulation treatment conditions and the addition concentrations of the 1 st coagulant G1 and the 2 nd coagulant G2 for each condition number.

Fig. 7 shows the organic matter concentration (TVS concentration) in the separated liquid N discharged from the concentration tank 30 for each condition number.

The coagulation treatment conditions of condition No. 1 correspond to the conventional art, and are the case of concentrating the sludge-containing liquid X using only the polymer coagulant as the 2 nd coagulant.

As shown in FIG. 7, the TVS concentration of the separated liquid N was about 1.6 g/L.

The flocculation treatment condition of condition No. 2 corresponds to the conventional technique, and is a case where a mixed sludge in which a sludge solubilized with ozone gas Q and a residue liquid are mixed is concentrated using only a polymer flocculant as the 2 nd flocculant.

As shown in FIG. 7, the TVS concentration of the separated liquid N was increased to about 2.7g/L due to the contamination of the solubilized sludge.

The flocculation treatment condition of condition No. 3 corresponds to the sludge treatment apparatus 100 and the sludge treatment method of the present embodiment, and is a case where the 1 st flocculant G1 and the 2 nd flocculant G2 are added to the mixed sludge obtained by mixing the sludge solubilized with the ozone gas Q and the residue liquid Z, and the sludge is concentrated.

As shown in FIG. 7, the TVS concentration of the separated liquid N was reduced to slightly more than about 1.2g/L, and the flocculation property was improved as compared with the conditions of

flocculation numbers

1 and 2.

The flocculation treatment condition of condition No. 4 corresponds to the sludge treatment apparatus 100 and the sludge treatment method of the present embodiment, and is a case where the 1 st flocculant G1 is added to the sludge solubilized with the ozone gas Q, and then the 2 nd flocculant G2 is added to the mixed sludge mixed with the residue liquid Z to concentrate the sludge.

As shown in FIG. 7, the TVS concentration of the separated liquid N was reduced to about 1.2g/L, and the flocculation property was improved as compared with the condition No. 3.

The coagulation treatment conditions of condition No. 5 were the same as those of condition No. 4, except that the amount of the first coagulant G1 added was increased.

As shown in FIG. 7, the TVS concentration of the separated liquid N was reduced to about 1.1g/L, and the flocculation property was improved as compared with that under condition No. 4.

From the results of the experiment, it was found that the organic matter concentration in the separation liquid N was reduced and the flocculant was efficiently used by adding the inorganic coagulant G1 to the sludge solution A2 solubilized with the ozone gas Q, mixing the residue liquid Z, and further adding the organic polymer coagulant G2 of No. 2.

Further, from the comparison result of condition No. 3 and condition No. 4, it was found that the concentration of organic matter in the separated liquid N decreased in condition No. 4 in which the residue liquid Z was mixed after the addition of the 1 st flocculant G1.

This is because the aggregated particles R1, which are formed by the combination of the first aggregating agent G1 and the fine particles of the solubilized sludge, are kept in an aggregated state even when they are mixed with the residual liquid Z thereafter.

According to the sludge treatment apparatus 100 and the sludge treatment method of the present embodiment configured as described above, the sludge-containing liquid X is solubilized with the ozone gas Q in the ozone reaction step S1 to generate the bubble sludge a1 (sludge solution a 2). By thus solubilizing the sludge, an accelerating effect in the following anaerobic treatment can be obtained, and the amount of methane gas T produced can be increased.

Further, the sludge is not flocculated in the front stage of the ozone reaction tank 10, and the sludge is flocculated in the rear stage of the ozone reaction tank 10. Therefore, the sludge-containing liquid X in the ozone reaction tank 10 has fluidity, and therefore the ozone gas Q and the sludge-containing liquid X are in contact with each other at a high efficiency. This can reduce the amount of ozone gas Q used.

In the 1 st addition step, a1 st flocculant G1 (inorganic flocculant in the present embodiment) having a small molecule is added to the bubble sludge a1 (sludge solution a2) micronized by the ozone gas Q to coagulate the bubble sludge a 1. This can effectively agglomerate the micronized sludge.

In addition, in the 1 st addition step, the foam sludge a1 (sludge solution a2) was mixed with the residue liquid Z to produce a mixed sludge solution B. By adding the residue liquid Z in this manner, the coagulation efficiency of the 2 nd coagulant G2 added later can be improved.

The addition tank 20 includes: the separation tank 21 to which the 1 st flocculant G1 was added and the mixing tank 22 to which the residual liquid Z was added at the subsequent stage were added, and the residual liquid Z was mixed with the sludge solution A2 to which the 1 st flocculant G1 was added. The aggregated particles R1 in which the 1 st aggregating agent G1 is bound to the fine particles of the solubilized sludge maintain an aggregated state even when subsequently mixed with the residue liquid Z, and therefore, an aggregated sludge with a large amount of organic matter can be obtained.

In addition, bubbles of the bubble sludge a1 supplied from the ozone reaction tank 10 are broken, whereby the bubble sludge a1 is separated into the exhaust gas H and the sludge solution a 2. Further, the 1 st flocculant G1 was added to the sludge solution a2 in a deaerated state. Therefore, the contact efficiency between the sludge solution a2 and the 1 st flocculant G1 is high, and the amount of the 1 st flocculant G1 added can be reduced.

In addition, the mixing tank 22 uses the residual liquid Z accumulated in the ozone reaction tank 10 as the treated water to be added to the sludge solution a 2. By using the residue liquid Z in this manner, it is not necessary to separately prepare treated water, and thus cost reduction can be achieved.

Further, in the thickening tank 30, a2 nd flocculant G2 (organic polymer flocculant in the present embodiment) is added to the mixed sludge solution B produced by adding the residue liquid Z. This improves the coagulation efficiency of the 2 nd coagulant G2, and can produce the concentrated sludge C having a large amount of organic matter. As described above, since the amount of organic matter in the concentrated sludge C is large, the amount of methane gas generated in the anaerobic digestion tank 40 can be increased, and larger thermal energy and electric energy can be obtained.

While an example in which an inorganic coagulant is used as the 1 st coagulant G1 is shown, a polymer coagulant containing a polymer as a main component may be used.

The mixing tank 22 mixes the sludge solution a2 with the residue liquid Z stored in the lower portion of the ozone reaction tank 10 as treated water, but tap water or the like may be used as the residue liquid Z.

Further, although a sludge treatment apparatus including the ozone reaction tank 10 and the addition tank 20 is shown as the sludge treatment apparatus 100, a sludge treatment apparatus in which the concentration tank 30 is added to the ozone reaction tank 10 and the addition tank 20 may be used as the sludge treatment apparatus, and a sludge treatment apparatus in which the anaerobic digestion tank 40 is further added may be used as the sludge treatment apparatus.

When ozone gas Q is continuously added to the solubilized sludge, the molecular weight of the sludge is further reduced, and the sludge is decomposed into organic acids. The solubilized sludge thus decomposed to the molecular level is difficult to coagulate with a coagulant. The particle size of the solubilized sludge that can be coagulated by the coagulant is in the range of 1 micron to submicron. In order to maintain the solubilization up to this level, it is necessary to control the amount of ozone gas Q to be absorbed by the sludge. The amount of ozone gas Q absorbed by the sludge attached to the bubbles in the ozone reaction tank 10 is in the range of 30mg to 150mg, and most preferably in the range of 50mg to 100mg, relative to the SS concentration 1g/L of the sludge.

Embodiment 2.

Hereinafter, embodiment 2 of the present invention will be described with reference to the drawings, focusing on differences from embodiment 1 described above. The same portions as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

Fig. 8 is a schematic configuration diagram showing a sludge treatment apparatus 200 according to embodiment 2 of the present invention.

In embodiment 1, the 1 st reservoir 25 for storing the 1 st flocculant G1 as an inorganic flocculant is connected to the separation tank 21. In the present embodiment, the 1 st reservoir 25 is connected to the pipe 23 connecting the separation tank 21 and the mixing tank 22.

Further, in embodiment 1, the separation tank 21 is provided with the agitator 24 as a defoaming unit, but in the present embodiment, a defoaming agent addition tank 224 as a defoaming unit is provided.

In the defoaming step, the separation tank 21 of the present embodiment is configured such that a defoaming agent is added to the foamed sludge a1 via the defoaming agent addition tank 224 to break up bubbles contained in the foamed sludge a1, thereby producing the sludge solution a 2.

Then, in the 1 st addition step of the present embodiment, the 1 st flocculant G1 is added to the sludge solution a2 flowing through the pipe 23. Since the 1 st flocculant G1 is added to the sludge solution a2 in a flowing state in this way, the 1 st flocculant G1 can be efficiently mixed with the sludge solution a 2.

According to the sludge treatment apparatus 200 and the sludge treatment method of the present embodiment configured as described above, the same effects as those of embodiment 1 can be obtained, and the amount of the ozone gas Q used can be reduced, thereby increasing the amount of organic matter in the flocculated sludge.

Further, since the 1 st flocculant G1 is added to the sludge solution a2 flowing through the pipe 23, the 1 st flocculant G1 and the sludge solution a2 can be efficiently mixed. Therefore, the agitator 24 for mixing the 1 st coagulant G1 and the sludge solution a2 in the separation tank 21 is not required, and the cost of the apparatus becomes inexpensive.

Embodiment 3.

Hereinafter, embodiment 3 of the present invention will be described with reference to the drawings, focusing on differences from embodiment 2 described above. The same portions as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

Fig. 9 is a schematic configuration diagram showing a sludge treatment apparatus 300 according to embodiment 3 of the present invention.

In the present embodiment, the pipe 23 includes: a mixer 326 for mixing the sludge solution A2 and the 1 st flocculant G1 in the pipe 23. The 1 st reservoir 25 is connected to the pipe 23 via the mixer 326.

As the mixer 326, an ejector, a static mixer, or the like can be used.

The ejector has a structure in which a flow path is provided with a throttle portion to increase or decrease the pressure of the liquid. If another liquid or gas is injected into a flow path in which the pressure of the liquid abruptly fluctuates, the injected liquid or gas is mixed with the liquid flowing in the injector due to the abrupt pressure fluctuation.

Static mixers are provided with plates that divide or mix the flow path, and the stirring effect is produced by these plates.

According to the sludge treatment apparatus 300 and the sludge treatment method of the present embodiment configured as described above, the same effects as those of embodiment 2 described above can be obtained, and the amount of the ozone gas Q used can be reduced, thereby increasing the amount of organic matter in the flocculated sludge.

Further, since the 1 st flocculant G1 is added to the sludge solution a2 flowing in the pipe 23, the 1 st flocculant G1 and the sludge solution a2 can be efficiently mixed.

Note that if an ejector or a static mixer is used, power of a stirrer or the like is not required for mixing, and thus cost reduction can be achieved.

Embodiment 4.

Hereinafter, embodiment 4 of the present invention will be described with reference to the drawings, focusing on differences from embodiment 1 described above. The same portions as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

Fig. 10 is a schematic configuration diagram showing a sludge treatment apparatus 400 according to embodiment 4 of the present invention.

An aerobic treatment section 50 which is provided in the front stage of the sludge treatment apparatus 400 and performs aerobic treatment by aerobic microorganisms is shown together with the sludge treatment apparatus 400.

The aerobic treatment section 50 includes: a first settling tank 51 for storing a waste liquid such as sewage and settling solids in the waste liquid; an aerobic digestion tank 52 as a treatment tank for performing aerobic treatment on the waste liquid from which the solid matter has been removed; and a final settling tank 53 for storing a sludge-containing liquid X containing excess sludge generated in the aerobic digestion tank 52.

The sludge-containing liquid X containing excess sludge generated in the final sedimentation tank 53 is supplied to the ozone reaction tank 10 in the same manner as in embodiment 1. Further, the sludge-containing liquid X or the sludge-containing liquid P, which is the primary sludge generated in the primary sedimentation tank 51, is supplied to the mixing tank 22 through the storage tank 54.

Thus, the mixing tank 22 has the following configuration: sludge solution A2 in which sludge-containing liquid X is solubilized with ozone gas Q and sludge-containing liquid X, P in an unsolubilized state are simultaneously coagulated in mixing tank 22.

In the case where a large amount of sludge-containing liquid X requiring anaerobic digestion is present, if all of the sludge-containing liquid X supplied from the aerobic treatment section 50 is subjected to the solubilization treatment with the ozone gas Q, a long treatment time is required, and the treatment cost may increase. In this case, if the sludge treatment apparatus 400 of the present embodiment is applied, the sludge-containing liquid X in which a required amount of methane gas can be obtained in the anaerobic digestion tank 40 from the sludge-containing liquid X supplied from the aerobic treatment section 50 can be supplied to the ozone reaction tank 10 to be subjected to the solubilization treatment, and the remaining sludge-containing liquid X is not subjected to the solubilization treatment. Thus, it is possible to shorten the processing time and reduce the processing cost.

Embodiment 5.

Hereinafter, embodiment 5 of the present invention will be described with reference to the drawings, focusing on differences from embodiment 1 described above. The same portions as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

Fig. 11 is a schematic configuration diagram showing a sludge treatment apparatus 500 according to embodiment 5 of the present invention.

Fig. 12 is a block diagram showing a sludge treatment apparatus 500 according to embodiment 5 of the present invention, in which an ozone reaction system using the ozone reaction tank 10 and the addition tank 20, a concentration system using the concentration tank 30, an anaerobic digestion system using the anaerobic digestion tank 40, and a dewatering system using the dewatering machine 60 are provided, and further showing the amount of sludge to be treated in each treatment system.

In the present embodiment, a dehydrator 60 as a 4 th treatment section is provided at a later stage of the anaerobic digestion tank 40 shown in embodiment 1.

The sludge treatment apparatus 500 of the present embodiment includes: an ozone reaction tank 10, an addition tank 20, a concentration tank 30, an anaerobic digestion tank 40, a digested sludge extraction pipe 61 as a digested sludge pipe, and a digested sludge return pipe 62 as a digested sludge pipe.

The digested sludge extraction pipe 61 is used to extract the digested sludge Y generated in the anaerobic treatment in the anaerobic digestion tank 40 from the anaerobic digestion tank 40. One end of the digested sludge extraction pipe 61 is connected to the anaerobic digestion tank 40, and the other end is connected to the dehydrator 60. One end of a digested sludge return pipe 62 that branches the digested sludge Y flowing through the digested sludge extraction pipe 61 is connected to an intermediate portion of the digested sludge extraction pipe 61. The other end of the digested sludge return pipe 62 is connected to the ozone reaction tank 10. Further, a digested sludge pump 63 for transferring the digested sludge Y in the digested sludge return pipe 62 to the ozone reaction tank 10 is provided in the middle of the digested sludge return pipe 62.

In the sludge treatment apparatus 500 configured as described above, the concentrated sludge C is supplied to the anaerobic digestion tank 40 by the same treatment as that described in embodiment 1. Then, if the concentrated sludge C is anaerobically treated, a digested sludge Y containing a digested product of the concentrated sludge C and a liquid containing anaerobic microorganisms is generated in the anaerobic digestion tank 40. This increases the amount of the digested sludge Y stored in the anaerobic digestion tank 40.

In order to efficiently perform the anaerobic treatment while taking the capacity of the anaerobic digestion tank 40 into consideration, it is necessary to keep the amount of the liquid of the digested sludge Y stored in the anaerobic digestion tank 40 constant. Therefore, it is necessary to extract the digested sludge Y from the anaerobic digestion tank 40 in an amount equal to the amount of the concentrated sludge C fed from the concentration tank 30 to the anaerobic digestion tank 40. Therefore, the same amount of digested sludge Y as the concentrated sludge C charged into the anaerobic digestion tank 40 is drawn out from the anaerobic digestion tank 40 through the digested sludge draw-out pipe 61. A part of the extracted digested sludge Y is returned to the ozone reaction tank 10 as returned digested sludge YA by the digested sludge return pipe 62. The surplus digested sludge Y is extracted and supplied to the dehydrator 60 through the digested sludge extraction pipe 61.

The digested sludge Y supplied to the dehydrator 60 is dehydrated and then incinerated.

As described below, the returned digested sludge YA returned to the ozone reaction tank 10 is one in which organic components are dissolved by the ozone gas Q.

The ozone reaction tank 10 injects ozone gas Q into the sludge-containing liquid X and the returned digested sludge YA. The injected ozone gas Q dissolves organic components contained in the sludge-containing liquid X and organic components contained in the returned digested sludge YA.

The returned digested sludge YA withdrawn from the anaerobic digestion tank 40 contains organic matter decomposed and refined by anaerobic microorganisms and organic matter having larger particles than the refined organic matter. Organic matter having large particles contained in the returned digested sludge YA is dissolved by the ozone gas Q together with organic matter contained in the sludge-containing liquid X, and then attached to and further dissolved in the bubble sludge a1 which is the 1 st sludge to be generated.

As described above, the organic matter contained in the sludge-containing liquid X and the organic matter contained in the returned digested sludge YA and having large particles are transferred to the separation tank 21 of the addition tank 20 while adhering to and being dissolved in the foam sludge a 1.

In the same manner as in embodiment 1, the separation tank 21 breaks up bubbles in the bubble sludge a1 to separate the bubble sludge a1 into the exhaust gas H and the sludge solution a2 that is the solubilized 1 st sludge. Further, in the separation tank 21, the 1 st flocculant G1 was added to the sludge solution a 2.

On the other hand, the organic matter having fine particles contained in the returned digested sludge YA is dissolved by the injection of the ozone gas Q and then is fine, and therefore does not adhere to the bubble sludge a1 and is mixed into the residue liquid Z as the returned sludge YB. The residue liquid Z containing the returned sludge YB is supplied to the mixing tank 22 of the addition tank 20. The mixing tank 22 adds a1 st flocculant G1 to the residue liquid Z containing the returned sludge YB. The mixing tank 22 mixes the residue liquid Z containing the returned sludge YB as treated water with the sludge solution a2 supplied from the separation tank 21 to produce a mixed sludge solution B as the 2 nd sludge.

The thickening tank 30 is configured to add a2 nd flocculant G2, which is an organic polymer flocculant, to the mixed sludge solution B supplied from the addition tank 20, in the same manner as in embodiment 1. The mixed sludge solution B is separated into a concentrated sludge C, which is a 3 rd sludge having sludge components aggregated, and a separated liquid N.

In this way, both the large-particle organic matter and the fine-particle organic matter contained in the returned digested sludge YA are flocculated by the first flocculating agent G1 in the addition tank 20, and are mixed into the concentrated sludge C in the concentration tank 30.

The generated concentrated sludge C is transferred to the anaerobic digestion tank 40, and anaerobic treatment is performed by anaerobic microorganisms. A part of the digested sludge Y newly generated by the anaerobic treatment is returned to the ozone reaction tank 10, and the remainder is supplied to the dehydrator 60.

The returned digested sludge YA returned to the ozone reaction tank 10 is separated into the concentrated sludge C and the separated liquid N in the concentration tank 30, and therefore the concentrated sludge C is higher in solid concentration than the digested sludge Y. The solid concentration of the digested sludge Y in the anaerobic digestion tank 40 is in the range of 15g/L to 25 g/L. The concentration of solids in the concentrated sludge C obtained from the concentration tank 30 is in the range of 30g/L to 60 g/L.

Hereinafter, the liquid amount of the digested sludge Y charged into the dewatering machine 60 will be described with reference to fig. 12, in which the digested sludge Y is returned to the ozone reaction tank 10 and in which the sludge is not returned.

In fig. 12, the liquid amount of returned digested sludge YA returned to the ozone reaction system is V1, the liquid amount of digested sludge Y treated by dehydrator 60 is V2, and the liquid amount of sludge-containing liquid X is liquid amount X1.

Further, NX represents the amount of separated liquid containing sludge X separated in the thickening system, and NV represents the amount of separated liquid returning digested sludge YA.

The amount of the concentrated sludge obtained by concentrating the sludge-containing liquid X in the concentration system is CX, and the amount of the concentrated sludge of the returned digested sludge YA is CV.

As described above, in order to keep the amount of the liquid of the digested sludge Y stored in the anaerobic digestion tank 40 constant, the same amount of the digested sludge Y as the concentrated sludge C charged into the anaerobic digestion tank 40 is extracted from the anaerobic digestion tank 40.

In the case where the digested sludge Y is not returned to the ozone reaction tank 10 (V1 is 0 and CV is 0), the amount of concentrated sludge charged into the anaerobic digestion tank 40 becomes the concentrated sludge amount CX containing the sludge liquid X. Therefore, the liquid amount of the digested sludge Y extracted from the anaerobic digestion tank 40 becomes CX, and the liquid amount V2 of the digested sludge Y treated by the dehydrator 60 becomes equal to CX.

V2 ═ CX (formula 1, case where digested sludge Y is not returned)

On the other hand, when the digested sludge Y is returned to the ozone reaction tank 10, the amount of the concentrated sludge charged into the anaerobic digestion tank 40 is CV + CX. Therefore, the amount of the digested sludge Y extracted from the anaerobic digestion tank 40 is CV + CX.

Therefore, the liquid amount V2 of the digested sludge Y treated by the dewatering machine 60 is CV + CX-V1.

V2 (CV + CX-V1 (in the case of returning digested sludge Y, equation 2)

In the thickening system, the liquid amount V1 of the returned digested sludge YA is separated into the separated liquid amount NV and the thickened sludge amount CV, and thus V1 is CV + NV (expression 3).

The liquid amount V2 of the digested sludge Y treated by the dehydrator 60 in accordance with

equations

2 and 3 is as follows.

V2 (CX-NV) (formula 2A, case of returning digested sludge Y)

If V1 is increased, NV is also increased, and V2 is decreased.

Wherein CX > NV

From the above formula 1 and formula 2A, it follows: the amount V2 of the digested sludge Y charged into the dehydrator 60 is reduced by returning the digested sludge Y in the anaerobic digestion tank 40 to the ozone reaction tank 10.

The amounts of NV and CX that satisfy the above-mentioned condition CX > NV need to be determined in advance. That is, the concentration ratio in the concentration system is considered in advance so that the amount CX of the concentrated sludge obtained by concentrating the sludge-containing liquid X becomes larger than the amount NV of the separated liquid of the returned digested sludge YA in the concentration system.

Hereinafter, the liquid amount V2 of the digested sludge Y treated by the dewatering machine 60 in the case where the compression ratio in the concentration system is 2 times will be described.

Fig. 13 is a diagram showing a relationship between the liquid amount V1 of returned digested sludge YA and the liquid amount V2 of digested sludge Y treated by the dewatering machine 60 in the sludge treatment apparatus 500 according to embodiment 5.

The liquid amount V1 of the returned digested sludge YA was concentrated 2 times in the concentration system, and the separated liquid amount NV and the concentrated sludge amount CV were equal to each other.

Since the separated liquid amount NV of the returned digested sludge YA is equal to the concentrated sludge amount CV of the returned digested sludge YA, the liquid amount V1 of the returned digested sludge YA becomes V1 ═ 2 × NV (expression 4).

The amount of liquid V2 fed into the dehydrator 60 is defined by the above equations 2A and 4

V2 ═ V1/2+ CX (formula 2B).

In formula 2B, when V1 is 0, V2 is CX.

If the liquid amount V1 of the returned digested sludge YA is equal to the concentrated sludge amount CX, V2 is equal to CX/2 in V2, and the liquid amount V1 of the digested sludge Y fed to the dehydrator 60 is half.

According to the sludge treatment apparatus 500 and the sludge treatment method of the present embodiment configured as described above, the digested sludge Y generated in the anaerobic digestion tank 40 is sent back and forth to the ozone reaction tank 10 as the returned digested sludge YA, and the returned digested sludge YA is subjected to the compression treatment in the concentration tank 30 provided at the subsequent stage of the ozone reaction tank 10.

This can reduce the amount V2 of the digested sludge Y fed to the dehydrator 60. Therefore, the dehydrator 60 can be downsized to save space and reduce cost.

Further, in addition to the organic matter contained in the sludge-containing liquid X, the organic matter contained in the returned digested sludge YA is also solubilized with the ozone gas Q and subjected to anaerobic treatment. This can increase the amount of methane gas T produced in the anaerobic treatment.

Further, the fine organic substances contained in the digested sludge Y are dissolved by the ozone gas Q and then contained in the residue liquid Z as the returned sludge YB. Further, by adding the 1 st flocculant G1 to the residue liquid Z containing the returned sludge YB, fine organic substances can be flocculated to obtain a concentrated sludge C having a large amount of organic substances.

In the present invention, the respective embodiments may be freely combined or may be appropriately modified or omitted within the scope of the invention.

Claims

1. A sludge treatment apparatus is provided with:

a1 st treatment part which is continuously supplied with a sludge-containing liquid, injects ozone gas into the sludge-containing liquid and foams the ozone gas, thereby separating the sludge-containing liquid into a bubble-shaped 1 st sludge and a residue liquid, and continuously flows out the 1 st sludge from an upper part and the residue liquid from a lower part; and

a2 nd treatment unit which is provided at a stage subsequent to the 1 st treatment unit, and which is configured to add a1 st flocculant as an inorganic flocculant to the 1 st sludge supplied from the 1 st treatment unit, and then mix the 1 st sludge with treatment water to produce a2 nd sludge,

the 2 nd processing unit includes:

a1 st tank for supplying the 1 st sludge from the 1 st treatment part, breaking up bubbles contained in the 1 st sludge in a bubble form, solubilizing the 1 st sludge, and adding the 1 st flocculant; and

a2 nd tank provided at a stage subsequent to the 1 st tank and configured to mix the treated water with the 1 st sludge to which the 1 st flocculant has been added to generate the 2 nd sludge,

the treatment apparatus is provided with a 3 rd treatment unit which is provided at a subsequent stage of the 2 nd treatment unit and generates a 3 rd sludge by adding a2 nd flocculant which is an organic polymer flocculant to the 2 nd sludge supplied from the 2 nd treatment unit.

2. The sludge treatment apparatus according to claim 1, comprising: a1 st reservoir portion for storing the 1 st coagulant,

the 1 st storage unit is connected to the 1 st tank, and the 1 st flocculant is added to the 1 st sludge in the 1 st tank.

3. The sludge treatment apparatus according to claim 1, comprising:

a1 st reservoir portion for storing the 1 st coagulant; and

a pipe for connecting the 1 st tank and the 2 nd tank,

the 1 st storage unit is connected to the pipe, and the 1 st flocculant is added to the 1 st sludge in the pipe.

4. The sludge treatment apparatus according to any one of claims 1 to 3, wherein the 2 nd treatment unit mixes the residual liquid accumulated in the 1 st treatment unit with the 1 st sludge as the treatment water.

5. The sludge treatment apparatus according to any one of claims 1 to 3, wherein the 2 nd tank mixes the 1 st sludge with a residual liquid stored in the 1 st treatment section as the treatment water.

6. The sludge treatment apparatus according to claim 3, wherein the piping includes: a mixer for mixing said 1 st sludge with said 1 st flocculant in said piping.

7. The sludge treatment apparatus according to any one of claims 1 to 3, comprising an anaerobic digestion tank provided at a stage subsequent to the 3 rd treatment section, wherein the 3 rd sludge supplied from the 3 rd treatment section is subjected to anaerobic treatment by anaerobic microorganisms to generate methane gas.

8. The sludge treatment apparatus according to claim 7, comprising a digested sludge pipe which supplies digested sludge generated by the anaerobic treatment in the anaerobic digestion tank to a 4 th treatment unit provided at a subsequent stage of the anaerobic digestion tank and returns the digested sludge to the 1 st treatment unit as returned digested sludge,

the 1 st treatment unit injects the ozone gas into the sludge-containing liquid and the returned digested sludge to generate the 1 st sludge and the returned sludge contained in the residual liquid stored in the 1 st treatment unit.

9. The sludge treatment apparatus according to claim 8, wherein in the 2 nd treatment section,

the first flocculant 1 is added to the 1 st sludge and the return sludge-containing residual liquid supplied from the 1 st treatment unit, and the 1 st sludge is produced by mixing the 1 st sludge and the residual liquid containing the return sludge as the treatment water.

10. The sludge treatment apparatus according to any one of claims 1 to 3, comprising an aerobic treatment section for producing the sludge-containing liquid,

the aerobic treatment section supplies the sludge-containing liquid to the 1 st treatment section and the 2 nd tank.

11. A sludge treatment apparatus is provided with:

a1 st treatment part which is continuously supplied with a sludge-containing liquid, injects ozone gas into the sludge-containing liquid and foams the ozone gas, thereby separating the sludge-containing liquid into a bubble-shaped 1 st sludge and a residue liquid, and continuously flows out the 1 st sludge from an upper part and the residue liquid from a lower part;

a2 nd treatment section provided at a stage subsequent to the 1 st treatment section, for producing a2 nd sludge by crushing bubbles contained in the 1 st sludge in a bubble form, solubilizing the 1 st sludge by adding a1 st flocculant as an inorganic flocculant to the 1 st sludge supplied from the 1 st treatment section, and then mixing the 1 st sludge to which the 1 st flocculant is added and the residue liquid separated from the sludge-containing liquid as treatment water; and

and a 3 rd treatment unit which is provided at a subsequent stage of the 2 nd treatment unit and which generates a 3 rd sludge by adding a2 nd flocculant which is an organic polymer flocculant to the 2 nd sludge supplied from the 2 nd treatment unit.

12. A sludge treatment method comprising:

an ozone reaction step of injecting ozone gas into the sludge-containing liquid continuously supplied to the 1 st treatment section and foaming the ozone gas to separate the sludge-containing liquid into a bubble-like 1 st sludge and a residue liquid, and continuously discharging the 1 st sludge from the upper part of the 1 st treatment section and the residue liquid from the lower part of the 1 st treatment section;

supplying the 1 st sludge separated from the sludge-containing liquid to a1 st tank;

a1 st addition step of taking out the separated 1 st sludge, dissolving the 1 st sludge by breaking up bubbles contained in the 1 st sludge in a bubble state, adding a1 st flocculant which is an inorganic flocculant, and then mixing the 1 st sludge to which the 1 st flocculant is added with treated water to produce a2 nd sludge; and

a2 nd addition step of adding a2 nd flocculant which is an organic polymer flocculant to the 2 nd sludge,

in the 1 st addition step, the 1 st sludge in the 1 st tank is supplied to a2 nd tank provided at a later stage of the 1 st tank, and the treated water is mixed with the 1 st sludge in the 2 nd tank to generate the 2 nd sludge.

13. The sludge treatment method according to claim 12, comprising: a defoaming step of defoaming the foamed sludge 1 by crushing,

in the 1 st addition step, the 1 st flocculant is added to the defoamed 1 st sludge.

14. The sludge treatment method according to claim 12 or 13, wherein the 1 st addition step mixes the 1 st sludge with the residual liquid as the treatment water.

15. A sludge treatment method comprising:

an ozone reaction step of injecting ozone gas into the sludge-containing liquid continuously supplied to the 1 st treatment section and foaming the same, thereby separating the sludge-containing liquid into a bubble-like 1 st sludge and a residual liquid, and continuously discharging the 1 st sludge from the upper portion of the 1 st treatment section and the residual liquid from the lower portion of the 1 st treatment section;

a1 st addition step of taking out the separated 1 st sludge, dissolving the 1 st sludge by breaking up bubbles contained in the 1 st sludge in a bubble state, adding a1 st flocculant as an inorganic flocculant, and then mixing the 1 st sludge to which the 1 st flocculant is added and the residue liquid separated from the sludge-containing liquid as treatment water to produce a2 nd sludge; and

and a2 nd addition step of adding a2 nd flocculant which is an organic polymer flocculant to the 2 nd sludge.