JP2002307072A - Method and apparatus for disinfecting wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus capable of effectively disinfecting even a confluent sewerage overflow water containing a suspended matter without reducing the activity of a disinfectant. SOLUTION: The wastewater disinfection method includes, as its feature, a flocculant adding process for adding a flocculant to wastewater and a disinfectant adding process for adding a bromine or iodine type disinfectant to wastewater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for disinfecting wastewater, and more particularly to a method and an apparatus for disinfecting sewage including rainwater. The present invention is particularly suitable for use in disinfecting combined sewer overflows.

[0002]

2. Description of the Related Art At present, general household wastewater and industrial wastewater are usually sent to a sewage treatment plant together with rainwater, and then the sedimentation basin treatment (sand removal) and the solid-liquid separation treatment (suspension material (SS) removal) are sequentially performed. After being subjected to purification and disinfection treatments including activated sludge treatment (organic matter decomposition) and disinfection processes, they are discharged into public water bodies such as rivers, lakes, marshes, ports and coastal seas. The sewer system that collects general household wastewater and industrial wastewater and rainwater in the same pipe and sends it to a sewage treatment plant is called "merging sewerage" .Sewage containing rainwater flowing through this merging sewer is mixed with rainwater. That.

In this combined sewer system, when a large amount of rainfall occurs and a large amount of sewage mixed with rainwater exceeding the amount that can be treated in the sewage treatment plant may flow in, a part of the sewage mixed with rainwater is left untreated. Water is discharged from sewage drainage facilities, such as rainwater discharge rooms and pump stations, into public water bodies. Some of the sewage mixed with rainwater is discharged only to sand basins at sewage treatment plants and then to public water bodies. The rainwater-containing sewage that contains a large amount of rainwater and is discharged without being treated is referred to as “combined sewer overflow”.

[0004] This combined sewage overflow generally contains coliforms (tens of thousands to hundreds of thousands of CFU / mL) which greatly exceed the discharge regulation value (3,000 CFU / mL). Regarding the target oxygen demand (BOD) and the suspended solids (SS), the release regulation values are 160 mg / L and 200 mg / L, respectively, whereas several tens to several hundreds mg / and several tens to several thousands mg / L. May be very high with L. From the viewpoint of pollution load on public water bodies and sanitation, discharge of combined sewer overflow into untreated public water bodies must be avoided. In addition,
CFU means Colony Forming Unit.

Conventionally, as a disinfectant in sewage treatment,
Chlorine-based disinfectants are widely used, but when disinfecting combined sewer overflows using a chlorine-based disinfectant, suspended substances contained in combined sewer overflows (particularly organic suspended substances) )), The disinfecting effect of the chlorinated disinfectant is reduced; if ammonium ions are contained in the combined sewer overflow, active chlorine, which is the disinfecting active component of the chlorinated disinfectant, is reduced to ammonium ions. Reacting to form chloramine and reduce bactericidal activity; disinfection effect cannot be obtained if the contact time is short; active chlorine remains in the system when a large amount of disinfectant is added; There is a problem.

Accordingly, the present applicant has proposed a method of adding a bromine-based disinfectant or an iodine-based disinfectant to a sand basin and disinfecting the wastewater while the sand basin is still standing, as an effective disinfection method particularly for combined sewer overflow water. Proposed. Bromine-based or iodine-based disinfectants do not reduce the disinfecting effect even in the presence of ammonium ions, have a shorter time required for disinfection than chlorine-based disinfectants, and have an excellent effect of less residual disinfecting active components. Is shown. However, even with these disinfecting methods,
The problem of the reduction of the disinfection effect due to the coexistence of suspended substances has not been solved.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and, in particular, to provide a method and apparatus capable of effectively disinfecting combined sewer overflow water. In particular, it is an object of the present invention to provide a method and an apparatus capable of effectively disinfecting the combined sewer overflow water containing a suspended substance without reducing the activity of the disinfectant.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies, and before disinfecting the wastewater with a disinfectant, floculated suspended substances in the wastewater with a flocculant. It was found that the disinfectant could maintain its disinfecting effect.

That is, according to the present invention, there is provided a method for disinfecting wastewater, which comprises adding a bromine-based or iodine-based disinfectant after adding a flocculant to the wastewater. The wastewater treated by the wastewater disinfection method of the present invention is preferably wastewater containing suspended solids, particularly sewage containing a large amount of rainwater, and is particularly effective for disinfecting combined sewer overflow water that has been conventionally discharged untreated. It is.

[0010] In the present invention, by adding a flocculant to the wastewater to make the suspended matter in the wastewater into fine flocs, the contact efficiency between the suspended matter in the wastewater and the disinfectant is reduced,
As a result, the disinfecting effect of the disinfectant due to the suspended substance can be suppressed from being reduced, and the disinfecting effect of the disinfectant can be maintained.

In order to effectively reduce the contact efficiency between the suspended solids in the wastewater and the disinfectant, after adding a flocculant to the wastewater,
It is preferable to add the disinfectant after a lapse of time sufficient to form minute flocs in the wastewater. In general,
The flocs of the suspended substance are not formed immediately after the addition of the flocculant, but become fine flocs after a certain period of time from the addition, and grow into large flocs with the passage of time. The disinfectant is preferably added after the generation of the fine floc. In the present invention, the disinfectant is added at least 5 seconds, preferably 7 seconds, more preferably 10 seconds after the addition of the flocculant. It is desirable to do.

As the flocculant used in the present invention, a flocculant selected from the group consisting of an inorganic flocculant, a polymer flocculant and a combination thereof can be used. Specifically, FeCl _3, PAC (polyaluminum chloride), the band sulphate (aluminum sulphate), Poritetsu (ferric polysulfate), an inorganic coagulant such as ferrous sulfate, polyvinyl sulfonates, polyacrylamides hydrolyzed Preferred examples include anionic polymer flocculants such as decomposition products, nonionic polymer flocculants such as polyacrylamide and polyvinyl alcohol, and cationic polymer flocculants such as polydialkylaminoethyl methacrylate. .

The preferred amount of coagulant added to the wastewater is
It depends on the S concentration. Generally, from the viewpoint of reducing the amount of generated sludge, it is preferable to use only a polymer flocculant without using an inorganic flocculant, and the addition amount at this time is preferably 0.1 to 2 mg / L, 0.2-0.5 mg / L is more preferred. In the case of an inorganic coagulant, for example, FeC
In the case of adding l ₃ it is preferable amount is 0~100m
g / L.

The bromine or iodine disinfectant used in the present invention includes, for example, hydantoins, cyanuric acids, isothiazolones, ε-caprolactams,
Phthalimides, pyrrolidones, acridones, uracils, succinimides, barbiturs, creatinines, dioxopiperazines, urazoles, glycine anhydrides, ω-heptalactams, maleic hydrazides, maleic imides And octalactams and oxindoles. These structural formulas are shown below.

[0015]

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Hydantoins are, for example,
It is represented by Formula II. In the above formula II, X ¹ and X ² are the same or different and are each independently a chlorine atom, a bromine atom or an iodine atom, provided that any one of X ¹ and X ² is a bromine atom or an iodine atom. R ¹ and R ² are the same or different and are each independently a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, preferably a hydrogen atom or a lower alkyl group having 6 or less carbon atoms And more preferably a hydrogen atom or a lower alkyl group having 3 or less carbon atoms. Examples of hydantoins include 1-bromo-3-chloro-5,5-dimethylhydantoin (the above formula
Compounds represented by I: BCDMH). Bromochlorodimethylhydantoin has high stability,
Avoiding direct sunlight can maintain activity for several years. BCDMH is a solid, and when dissociated, hypobromite ion is generated to exhibit a high disinfecting effect.

Cyanuric acids are represented, for example, by the formula III above. In formula III, R ¹ , R ² and R
³ is the same or different and is independently a chlorine atom, a bromine atom, an iodine atom, a hydroxyl group, a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, provided that R ¹ , R ² and R ³ At least one is a bromine atom or an iodine atom. The lower alkyl group preferably has 6 or less carbon atoms, and more preferably 3 or less carbon atoms.

Isothiazolons are represented, for example, by the above formula IV. In formula IV, X is a bromine or iodine atom; R ¹ and R ² are each the same or different and are independently chlorine, bromine, iodine,
It is a hydrogen atom or a lower alkyl group having 10 or less carbon atoms.
The lower alkyl group preferably has 6 or less carbon atoms, and more preferably 3 or less carbon atoms. For example, 5-chloro-2-methyl-4-isothiazolin-3-one is preferred.

Ε-caprolactams
s) is represented, for example, by the above formula V. In the formula V, X is a bromine atom or an iodine atom. Phthalimides (phthali
mides) is represented, for example, by the above formula VI. In Formula VI, X is
It is a bromine atom or an iodine atom.

Pyrrolidones are, for example,
It is represented by the above formula VII. In Formula VII, X is a bromine atom or an iodine atom. Acridones (acrydones) are, for example,
It is represented by the above formula VIII. In the formula VIII, X is a bromine atom or an iodine atom.

Uracils are, for example, of the formula IX
Indicated by In the formula IX, X ¹ and X ² are the same or different and are each independently a chlorine atom, a bromine atom or an iodine atom, provided that any one of X ¹ and X ² is a bromine atom or an iodine atom R ¹ is a hydrogen atom, carbon number 10
The following are lower alkyl groups, amino groups or nitro groups.
The lower alkyl group preferably has 6 or less carbon atoms, and more preferably 3 or less carbon atoms. R ² and R ³ are the same or different and are each independently a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, preferably a hydrogen atom or a lower alkyl group having 6 or less carbon atoms, Preferably, it is a hydrogen atom or a lower alkyl group having 3 or less carbon atoms.

Succinimides are represented, for example, by the formula X above. In the formula X, X is a bromine atom or an iodine atom.

[0023]

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[0024] Barbituric acids are
For example, it is represented by the above formula XI. In the formula XI, X ¹ and X ² are the same or different and are each independently a chlorine atom, a bromine atom or an iodine atom, provided that any one of X ¹ and X ² is a bromine atom or an iodine atom R ¹ and R ² are
Each is the same or different and is independently a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, preferably
It is a hydrogen atom or a lower alkyl group having 6 or less carbon atoms, and more preferably a hydrogen atom or a lower alkyl group having 3 or less carbon atoms.

The creatinines are represented, for example, by the above formula XII. In the formula XII, X is a bromine atom or an iodine atom; R is a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, preferably a hydrogen atom or a lower alkyl group having 6 or less carbon atoms, Preferably,
It is a hydrogen atom or a lower alkyl group having 3 or less carbon atoms.

Dioxopiperazines
Is represented, for example, by the above formula XIII. In the formula XIII, X ¹ and X ² are the same or different and are each independently a chlorine atom, a bromine atom or an iodine atom, provided that any one of X ¹ and X ² is a bromine atom or an iodine atom It is.

Urazoles are, for example,
Indicated by XIV. In the formula XIV, R ¹ , R ² and R ³ are the same or different and are each independently a chlorine atom, a bromine atom, an iodine atom, a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, provided that Any of R ¹ , R ² and R ³ is a bromine atom or an iodine atom. The lower alkyl group preferably has 6 or less carbon atoms, and more preferably 3 or less carbon atoms.

Glycine anhydrides
Is represented, for example, by the above formula XV. In the formula XV, X ¹ and X
² is the same or different and is independently a chlorine atom, a bromine atom, an iodine atom, a hydrogen atom or a lower alkyl group having 10 or less carbon atoms, and any one of X ¹ and X ² is a bromine atom or It is an iodine atom. The lower alkyl group preferably has 6 or less carbon atoms, and more preferably 3 or less carbon atoms.

Ω-heptalactams
s) is represented, for example, by the above formula XVI. In Formula XVI, X is
It is a bromine atom or an iodine atom. Maleic acid hydrazides are represented, for example, by the above formula XVII. In the formula XVII, X ¹ and X ² are the same or different and are each independently a chlorine atom, a bromine atom or an iodine atom, provided that any one of X ¹ and X ² is a bromine atom or an iodine atom It is.

Maleimides are represented, for example, by the above formula XVIII. In the formula XVIII, X is a bromine atom or an iodine atom.

[0031]

Embedded image

Octalactams are represented, for example, by the above formula XIX. In the formula XIX, X is a bromine atom or an iodine atom. Oxindoles
Is represented, for example, by the above formula XX. In the formula XX, X is a bromine atom or an iodine atom.

The disinfectant which can be used in the present invention preferably contains a 4- to 10-membered heterocyclic ring containing a nitrogen atom or a sulfur atom, as shown in the above formulas (I) to (XX). More preferably, it contains a to 9-membered heterocyclic ring. The heterocycle preferably contains 1 to 4 heteroatoms,
More preferably, it contains three heteroatoms. Heteroatoms are nitrogen or sulfur atoms.

In the ring skeleton of the heterocyclic ring, a group represented by the formula -N (X)-(X is a chlorine atom, a bromine atom or an iodine atom, preferably a bromine atom or an iodine atom, more preferably Is a bromine atom.).

[0035]

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As shown in the above formula XXI, the ring skeleton of the heterocycle A has a group represented by the formula -N (X) -C (= O)-(wherein X is a bromine atom or an iodine atom). Is more preferable. This is because, in the case of this structure, hypohalous acid is particularly easily generated.

The heterocyclic ring may be condensed with another ring, for example, an aromatic ring such as a benzene ring, as shown by the above formulas VI, VIII and XX. In the method of the present invention, 1-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH) can be particularly preferably used as a disinfectant.

In the present invention, it is preferable to add the above-mentioned disinfectant to wastewater in a liquid state. It is not preferable to add a solid disinfectant directly to wastewater because undissolved solids are discharged together with the wastewater, which may adversely affect aquatic organisms in public water bodies. Therefore, when the above-mentioned disinfectant is solid at room temperature, it is preferable to sufficiently dissolve the disinfectant in water or a part of the wastewater to make the disinfectant water, and then to add the disinfectant to the wastewater.

The amount of the disinfectant added was SS content, COD,
Although it differs depending on the BOD, it is generally preferably 0.5 to 25 mg / L as Cl in terms of active chlorine concentration,
More preferably, it is 1 to 15 mg / L as Cl.

In the present invention, further, at or after the addition of the disinfectant, the wastewater to which the disinfectant has been added is stirred,
It is then desirable to separate the flocs formed in the wastewater. By stirring the wastewater after adding the disinfectant, the contact efficiency between the wastewater and the disinfectant is increased, and the disinfecting action can be enhanced.

In order to sufficiently exhibit the disinfecting effect, it is desirable that the waste water and the disinfectant are brought into contact with each other for at least 10 seconds, preferably 30 seconds or more. After the wastewater is sufficiently disinfected according to the method according to the present invention as described above, the suspended substances in a floc state are removed from the wastewater, and the treated water can be obtained and discharged to public water bodies. The floc can be removed by a method known in the art, such as sedimentation separation using a sedimentation tank and filtration using a filter medium.

[0042]

Preferred embodiments will be described below with reference to the accompanying drawings.
Preferred embodiments of the present invention will be described, but the present invention is not limited thereto.

FIG. 1 is a schematic sectional view of a waste water disinfection apparatus according to a first embodiment of the present invention. In this embodiment,
The disinfection device includes a wastewater supply line L1 and a flocculant supply line
A solid-liquid separation tank 1 including a coagulant addition section to which L2 is connected, a disinfectant addition section located downstream of the coagulant addition section, and a floc separation section located downstream of the disinfectant addition section.
It is configured as

The solid-liquid separation tank 1 has an outflow pipe 2 for treated water at the upper part, and an outflow pipe 3 for concentrated sludge (and separated floc) at the bottom. Inside the solid-liquid separation tank 1, a draft tube 4 extending from above to near the center is provided substantially at the center, and a drainage supply line L1 and a flocculant supply line L2 are connected to the draft tube 4 at the upper part. Inflow pipe 5
(Coagulant addition section) is connected. A rotary shaft 6 communicating with the lower portion of the solid-liquid separation tank 1 is provided along the center line of the draft tube 4, and the rotary shaft 6 is provided with a multi-stage stirring blade 7 at a lower portion in the draft tube 4. Is fixed,
Immediately below the draft tube 4, multi-stage stirring blades 9 are fixed. Further, a blocking plate 8 having a dimension longer than the inner diameter of the draft tube 4 is fixed to the rotating shaft 6 below the stirring blade 9. A picket fence and a scraper 10 are fixed to the rotating shaft 6 below the solid-liquid separation tank 1.

On the outer periphery of the draft tube 4 of the solid-liquid separation tank 1, the filter medium receiving screen 1
1. A stirring rod 12 fixed to the rotating shaft 6, a contact filter medium layer 13, and a filter medium outflow prevention screen 14 are sequentially provided (flock separation section).

A procedure for performing the wastewater disinfection method of the present invention using the solid-liquid separation tank 1 will be described. The coagulant is added from the coagulant supply line L2 to the drainage from the drainage supply line L1, and the mixed wastewater and coagulant are passed through the inflow pipe 5 and flow into the draft tube 4 in the solid-liquid separation tank 1. Let it. In the wastewater to which the flocculant has been added, the formation of fine flocs progresses due to the association between the suspended solids in the wastewater and the flocculant. Next, a disinfectant is added in a liquid state to wastewater containing fine flocs. The disinfectant should be added at a position after the generation of the fine floc, and may be at the point A in the inflow pipe 5, but preferably at the point B in the draft tube 4,
More preferably, a disinfectant is added at point C. The wastewater containing fine flocs and containing the disinfectant is stirred by the stirring blade 7 while flowing down the draft tube 4. Next, the drainage flowing down from the draft tube 4 collides with the blocking plate 8 and becomes an upward flow, which is further stirred by the stirring blade 9. Thus, the wastewater comes into full contact with the disinfectant, while some of the flocs formed from the suspended solids contained in the wastewater become dense pellets upon stirring. Pellets with a high sedimentation speed (densified pellets) settle at the lower part of the solid-liquid separation tank 1, and pellets with a low sedimentation speed and undensified flocs reach the contact filter layer 13 together with the drainage. The contact filter medium layer 13 separates and removes waste water and solids (pellets with slow sedimentation speed and undensified flocs),
The liquid component that has passed through the contact filter medium layer 13 is discharged as treated water into the public water area via the outflow pipe 2.

FIG. 2 is a schematic flow chart showing a waste water disinfection apparatus according to another embodiment of the present invention. In this embodiment,
The waste water disinfecting apparatus includes a coagulant addition tank 2 to which a waste water supply line L11 and coagulant supply lines L21 and L22 are connected.
0, 21 and a floc forming tank 22 connected in a fluid communication state to the downstream side of the flocculant addition tanks 20 and 21, and an inclined plate 23 connected in a fluid communication state to a downstream side of the floc forming tank 22. Separation tank 24 provided with an outlet pipe 26 for discharging the treated water from which the flocs have been separated and removed.
And. In the illustrated embodiment, the coagulant addition line includes a polymer coagulant addition line L21 and an inorganic coagulant addition line L22, and the coagulant addition tank includes a rapid stirring tank 20 and an injection stirring tank 21. Rapid stirring tank 2
At 0, a drainage supply line L11 is connected to the lower part, and an inorganic coagulant addition line L22 is connected to the upper part. On the downstream side of the rapid stirring tank 20, an injection stirring tank 21 is provided so as to be in fluid communication with the rapid stirring tank 20 at an upper part of the tank.
A polymer flocculant supply line L21
Is connected. A floc forming tank 22 is provided downstream of the pouring and stirring tank 21 so as to be in fluid communication with a lower part of the tank. A flock separation tank 24 is provided downstream of the flock forming tank 22 so as to be in fluid communication with the upper part of the tank. In the illustrated embodiment, the floc separation tank is configured as a sedimentation tank 24 having an inclined plate 23 at the top, a sludge sedimentation section 25 at the bottom, and a treated water outflow pipe 26 at the top of the tank downstream of the inclined plate 23. I have. The apparatus of the illustrated embodiment further includes a liquid cyclone 27 connected in fluid communication with the sedimentation tank 24 to separate and collect particulate matter such as sand from the sludge sediment and return the same to the injection and stirring tank 21. Are located in Further, each of the rapid stirring tank 20, the injection stirring tank 21 and the floc forming tank 22 is provided with a stirring blade at the center of the tank.

Next, a drainage disinfection procedure when the drainage disinfection apparatus shown in FIG. 2 is used will be described. First, the drainage supply line L
The wastewater is supplied to the rapid stirring tank 20 via the liquid 11 and the inorganic coagulant is added into the tank via the inorganic coagulant addition line L22. The liquid inside the rapid stirring tank 20 is stirred by a stirring blade in order to increase the contact efficiency with the drainage and the inorganic coagulant. Next, the wastewater containing the inorganic coagulant overflows into the pouring and stirring tank 21, where the polymer coagulant is added into the tank via the polymer coagulant supply line L21. Even in the injection stirring tank 21,
In order to increase the contact efficiency between the waste water and the flocculant, the liquid is stirred by stirring blades. Next, drainage containing an inorganic coagulant and a polymer coagulant is caused to flow out to the floc forming tank 22, where
The floc is formed and grown by the association between the suspended solids in the wastewater and the flocculant, and the dense pellets are formed by continuing the stirring. Since the disinfectant should be added after the formation of the fine floc, the floc forming tank 22
At point D, preferably point E, more preferably point F, the disinfectant is added in a liquid state, and the liquid is stirred by a stirring blade. By this stirring, the contact efficiency between the wastewater and the disinfectant is increased. Next, the drainage containing the disinfectant and the pellets and flocs is overflowed into the sedimentation tank 24 and passed through the inclined plate 23,
Separate into sludge containing pellets and flocs, and treated water. Sludge settles in the sludge settling section at the bottom of the settling tank 24. The treated water is discharged through a treated water outflow pipe 26 provided on the downstream side of the inclined plate 23.

The sludge collected in the sludge sedimentation section 25 is sent to the liquid cyclone 27 via the sludge delivery line L25, where it is separated into sludge and particulate matter (microsand) such as sand. Is done. Sludge is discharged from the hydrocyclone 27 and treated in a conventional procedure. The particulate matter (micro sand) is returned to the pouring and stirring tank 21. In this way, the microsand is injected into the stirring tank 2.
In addition to the coagulation and sedimentation treatment in step 1, microsand is taken into the floc and the sedimentation speed of the floc increases,
High-speed precipitation processing becomes possible. The sand is separated and recovered from the flocs in the cyclone and reused.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example, the results of a processing experiment of the wastewater disinfection method of the present invention performed using the wastewater disinfection apparatus shown in FIG. 1 will be described below. Simulated wastewater prepared by diluting sewage containing E. coli with pure water was used as the water to be treated. Table 1 shows the water quality of the simulated wastewater.

[0051]

[Table 1]

As a flocculant, a cationic polymer flocculant (manufactured by Ehara Seisakusho, trade name: Ebagrose CS280), and as a disinfectant, 1-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH) (manufactured by Ebara Seisakusho) Evasany 4400) was used. In Experiments 1 and 2, the bactericidal effect on the Escherichia coli group was observed by changing the amount of the disinfectant added and changing the amount of the polymer flocculant and the time from the addition of the flocculant to the addition of the disinfectant. Table 2 shows the experimental conditions and results.

[0053]

[Table 2]

From the above experimental results, it can be seen that the addition of the flocculant significantly reduced the number of remaining Escherichia coli to the emission regulation value (3000 CFU / mL) or less, compared to the case where only the disinfectant was added, and the disinfection was effectively performed. You can see that the processing was successful. Also, it can be seen that the longer the time from the addition of the flocculant to the addition of the disinfectant, the more effective the disinfection treatment.

[0055]

According to the present invention, wastewater containing suspended substances is provided,
In particular, sewage including rainwater, more preferably combined sewer overflow can be efficiently disinfected. In particular, according to the method of the present invention, it is possible to maintain the active state without impairing the disinfecting activity which was inhibited by the suspended substance in the conventional method, and as a result, the amount of disinfectant used is reduced. It is possible.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a disinfecting apparatus of the present invention suitable for performing a disinfecting method of the present invention.

FIG. 2 is a schematic flowchart showing another embodiment of the disinfecting apparatus of the present invention.

[Explanation of symbols]

1: Solid-liquid separation tank 2: Treated water outflow pipe 3: Sludge outflow pipe 4: Draft tube 5: Drainage / coagulant inflow pipe 7: Stirring blade 8: Blocking plate 9: Stirring blade L1; L11: Drainage supply line L2: Coagulant supply line L21: Polymer coagulant supply line L22: Inorganic coagulant supply line 20: Rapid stirring tank 21: Injection stirring tank 22: Flock forming tank 23: Inclined plate (flock separation site) 24: Precipitation tank 26: Treatment Water outflow pipe L25: Sludge delivery line 27: Liquid cyclone A, B, C, D, E, F: Disinfectant addition position

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 560 C02F 1/50 560Z A01N 43/36 A01N 43/36 C 43/38 43/38 43 / 42 43/42 43/46 43/46 43/50 43/50 Q 43/54 43/54 F 43/64 105 43/64 105 43/828 B01D 21/01 C B01D 21/01 21/02 E 21 / 02 21/08 B 21/08 C02F 1/52 E C02F 1/52 A01N 43/82 102 F term (reference) 4D015 BA19 BA23 DA04 DA05 DA13 DA16 DB07 DB08 DB14 DC02 FA02 FA11 4H011 AA02 BA01 BB09 BC18

Claims (5)

[Claims] 1. A method for disinfecting wastewater, comprising: a coagulant addition step of adding a coagulant to wastewater; and a disinfectant addition step of adding a bromine-based or iodine-based disinfectant to wastewater. A method comprising: 2. The method according to claim 1, wherein the coagulant is added to the wastewater, and the disinfectant is added after a lapse of time sufficient to form fine flocs in the wastewater. 3. The wastewater to which the disinfectant has been added is stirred at the time of or after the disinfectant addition step, and then the flocs formed in the wastewater are separated. the method of. 4. An apparatus for disinfecting wastewater, comprising: a coagulant addition section to which a drainage supply line and a coagulant supply line are connected; a disinfectant addition section located downstream of the coagulant addition section; A floc separating unit located downstream of the adding unit. 5. An apparatus for disinfecting wastewater, comprising: a flocculant addition tank to which a wastewater supply line and a flocculant supply line are connected; and a floc formed to be in fluid communication with a downstream side of the flocculant addition tank. An apparatus comprising: a tank; and a flock separation tank, which is connected to a downstream side of the flock forming tank in a fluid communication state and includes an inclined plate.