JP2011212622A - Apparatus and method for treating waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for treating waste water, capable of treating waste water without degrading the activity of methanation treatment with methanogen in an anaerobic treatment environment.SOLUTION: The apparatus and method for treating waste water includes: a sulfuric acid reduction reaction vessel 2 for performing anaerobic treatment of throwing-in sulfate-reducing bacteria, taking-in waste water to be treated and reducing sulfate ions in waste water with sulfate-reducing bacteria to decompose an organism and generate hydrogen sulfide; a methane fermentation vessel 3 for performing anaerobic treatment of throwing-in methanogen, taking-in waste water treated in the sulfuric acid reduction reaction vessel 2 and decomposing an organism in the waste water not decomposed in the sulfuric acid reduction reaction vessel 2 with methanogen; and biological desulfurization treatment vessel 4 for throwing-in sulfur oxidation bacteria, taking-in hydrogen sulfide generated in the sulfuric acid reduction reaction vessel and performing desulfurization treatment with sulfur oxidation bacteria to generate sulfuric acid and to feed water to the sulfuric acid reduction reaction vessel for use of the generated sulfuric acid in the reduction of sulfuric acid ions.

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method for removing organic substances from wastewater such as industrial wastewater and sewage.

  Conventionally, there is a technique for removing organic substances by biologically treating wastewater such as industrial wastewater and sewage. For example, there is a wastewater treatment apparatus described in Patent Document 1 that uses a technique for treating wastewater by biological treatment.

  As shown in FIG. 13, the wastewater treatment apparatus 100 described in Patent Document 1 is configured to remove hydrogen sulfide generated by the treatment in the anaerobic treatment tank 110 after the organic substance is decomposed in the anaerobic treatment tank 110. In the aerobic treatment tank 120 and the biological deodorization apparatus 130, the waste water is efficiently treated by desulfurization and returning to the anaerobic treatment tank 110.

Specifically, as shown in Chemical Formula 1, in the anaerobic treatment tank 110, as shown in the formula (1), first, high molecular organic substances (carbohydrates, proteins, lipids) in the waste water are decomposed into low molecular organic substances by hydrolyzing bacteria. After that, low molecular organic substances are decomposed into lower fatty acids (acetic acid, propionic acid, etc.) by acid producing bacteria as shown in formula (2), and finally, by methanogenic bacteria as shown in formula (3). It is decomposed from lower fatty acids such as acetic acid into methane (CH ₄ ) and carbon dioxide (CO ₂ ).

In the anaerobic treatment tank 110, as shown in the formula (4), the sulfate-reducing bacteria reduce the sulfate ions (SO ₄ ²⁻ ) returned from the aerobic treatment tank 120 and the biological deodorization device 130, so Are decomposed to produce hydrogen sulfide (H ₂ S), carbon dioxide, and water (H ₂ O).

  In the aerobic treatment tank, organic substances that could not be decomposed in the anaerobic treatment tank are decomposed by aerobic microorganisms containing sulfur-oxidizing bacteria.

Moreover, in an aerobic processing tank, as shown to Formula (5), a sulfur oxidation bacterium oxidizes hydrogen sulfide, and thereby a sulfate ion and a hydrogen ion (H ⁺ ) are generated. The produced sulfate ions are returned to the anaerobic treatment tank.

  In the biological deodorization apparatus 130, as in the aerobic treatment tank 120, sulfate ions and hydrogen ions are generated by sulfur-oxidizing bacteria oxidizing hydrogen sulfide. The produced sulfate ions are returned to the anaerobic treatment tank.

[Chemical 1]
High molecular organic substances (carbohydrates, proteins, lipids) + H ₂ O
→ Low molecular weight organic matter (1)
Low molecular weight organic compounds → Lower fatty acids (acetic acid, propionic acid, etc.) (2)
CH ₃ COOH → CH ₄ + CO ₂ (3)
SO ₄ ²⁻ + CH ₃ COOH + 2H ⁺ → H ₂ S + 2CO ₂ + 2H ₂ O
(4)
H ₂ S + 2O ₂ → SO ₄ ²⁻ + 2H ⁺ (5)
Thus, the hydrogen sulfide (H ₂ S) generated by the reaction shown in the formula (4) in the anaerobic treatment tank 110 is desulfurized in the aerobic treatment tank 120 and the biological deodorization apparatus 130 as shown in the formula (5). In this way, sulfate ions (SO ₄ ²⁻ ) are generated and returned to the anaerobic treatment tank 110, whereby a sulfur circulation is formed as shown in FIG.

  By the above-described treatment, organic substances such as high molecules, low molecules, and acetic acid are decomposed into methane and carbon dioxide, and the organic substances in the wastewater are reduced and discharged into public water bodies.

JP 2004-148242 A

  By the way, in the anaerobic treatment tank 110 described above, methane-producing bacteria and sulfate-reducing bacteria coexist, and methane production treatment by the methane-producing bacteria of the above formula (3) and hydrogen sulfide by the sulfate-reducing bacteria of the formula (4). Of these, hydrogen sulfide generation treatment with sulfate-reducing bacteria is faster than methane formation treatment with methanogens, so sulfate-reducing bacteria are more active than methanogens .

  In addition, the sulfate ions generated in the aerobic treatment tank 120 and the biological deodorization apparatus 130 are returned to the anaerobic treatment tank 110, and the concentration of sulfate ions as a substrate of the sulfate-reducing bacteria is increased. Get higher.

However, since hydrogen sulfide (H ₂ S) is toxic to the human body and causes corrosion of the duct in the waste water treatment apparatus 100, it is not preferable to accelerate the activity of sulfate-reducing bacteria. It is desired to increase the activity of methanogenic treatment by competing methanogens.

  The present invention has been made in view of the above circumstances, and provides a wastewater treatment apparatus and a wastewater treatment method capable of performing wastewater treatment in an anaerobic treatment environment without reducing the activity of methane production treatment by methanogens. The purpose is to provide.

  In order to achieve the above object, the wastewater treatment apparatus of the present invention is provided with sulfate-reducing bacteria, which takes in the wastewater to be treated and reduces sulfate ions in the wastewater by the sulfate-reducing bacteria, thereby decomposing organic matter and sulfide. A sulfuric acid reduction reaction tank that performs anaerobic treatment to generate hydrogen, and a wastewater treated with the sulfuric acid reduction reaction tank, into which methanogenic bacteria are introduced, and organic matter in the wastewater that has not been decomposed in the sulfuric acid reduction reaction tank. A methane fermenter that performs anaerobic treatment that decomposes by the methanogen, and a sulfur-oxidizing bacterium are added, and the sulfuric acid is removed by taking in the hydrogen sulfide generated in the sulfuric acid reduction reaction tank and performing a desulfurization treatment by the sulfur-oxidizing bacterium. And a biodesulfurization treatment tank that feeds water to the sulfuric acid reduction reaction tank in order to use the produced sulfuric acid for the reduction of the sulfate ions.

  In addition, the waste water treatment apparatus includes a first sulfur stripping means for performing sulfur stripping in the waste water by aeration of the hydrogen sulfide generated in the sulfuric acid reduction reaction tank into the waste water of the sulfuric acid reduction reaction tank, You may further provide the 2nd sulfur stripping means which performs the sulfur stripping in waste_water | drain by sprinkling the waste_water | drain processed in the said sulfuric acid reduction reaction tank in the gaseous phase of the said sulfuric acid reduction reaction tank.

  In addition, the wastewater treatment apparatus takes in the wastewater treated with the aerobic bacteria and treated with the methane fermentation tank, and removes organic matter in the wastewater that has not been decomposed with the sulfuric acid reduction reaction tank and the methane fermentation tank. You may further provide the aerobic processing tank which performs the aerobic process decomposed | disassembled by microbe.

  The waste water treatment apparatus may further include waste water supply means for supplying waste water treated in the methane fermentation tank to the biological desulfurization treatment tank.

  The wastewater treatment apparatus may further include a filtration means for removing suspended substances or a heat treatment means for decomposing proteins upstream of the sulfuric acid reduction reaction tank.

  The waste water treatment apparatus may further include a sulfur supply means for supplying sulfur to the sulfuric acid reduction reaction tank.

  In addition, a carrier to which sulfate-reducing bacteria are attached is introduced into the sulfuric acid reduction reaction tank of the wastewater treatment apparatus, a mass of methanogenic bacteria is introduced into the methane fermentation tank, and the biological desulfurization treatment tank is attached to the carrier. The sulfur-oxidizing bacteria that have been added may be introduced.

  In the wastewater treatment method of the present invention, the wastewater treatment apparatus takes the wastewater to be treated into the sulfuric acid reduction reaction tank and reduces sulfate ions in the wastewater by the sulfate reducing bacteria introduced into the sulfuric acid reduction reaction tank. Anaerobic treatment to decompose the organic matter and generate hydrogen sulfide is performed, and the wastewater treated in the sulfuric acid reduction reaction tank is taken into the methane fermentation tank, and the organic matter in the wastewater not decomposed in the sulfuric acid reduction reaction tank is Sulfur-oxidizing bacteria that are subjected to anaerobic treatment that is decomposed by the methane-producing bacteria charged in the methane fermentation tank, take in the hydrogen sulfide produced in the sulfuric acid reduction reaction tank to the biological desulfurization treatment tank, and are introduced into the biological desulfurization treatment tank In this method, sulfuric acid is generated by performing a desulfurization treatment by the above-described method, and water is sent to a sulfuric acid reduction reaction tank so that the generated sulfuric acid can be used for reduction of the sulfate ion.

  According to the waste water treatment apparatus and the waste water treatment method of the present invention, stable waste water treatment can be performed in an anaerobic treatment environment without reducing the activity of the methane production treatment by the methanogen.

It is explanatory drawing which shows the structure of the waste water treatment equipment by 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the sulfuric acid reduction reaction tank of the waste water treatment equipment by 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the methane fermenter of the waste water treatment apparatus by 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the biological desulfurization processing tank of the waste water treatment equipment by 1st Embodiment of this invention. It is a perspective view which shows the structure of the sulfur oxidation bacteria adhesion support | carrier of the biological desulfurization processing tank of the waste water treatment equipment by 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the waste water treatment equipment by 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of the sulfuric acid reduction reaction tank which provided the 1st sulfur stripping means of the waste water treatment equipment by 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of the sulfuric acid reduction reaction tank provided with the 2nd sulfur stripping means of the waste water treatment equipment by 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of the waste water treatment equipment by 3rd Embodiment of this invention. It is explanatory drawing which shows the structure of the waste water treatment equipment by 4th Embodiment of this invention. It is explanatory drawing which shows the structure of the waste water treatment equipment by 5th Embodiment of this invention. It is explanatory drawing which shows the structure of the waste water treatment equipment by 6th Embodiment of this invention. It is explanatory drawing which shows the structure of the conventional waste water treatment equipment. It is explanatory drawing which shows the content of the biodegradation performed by the conventional waste water treatment equipment.

<< First Embodiment >>
The configuration of the wastewater treatment apparatus 1A according to the first embodiment of the present invention will be described with reference to FIG.

  A wastewater treatment apparatus 1 </ b> A according to this embodiment includes a sulfuric acid reduction reaction tank 2, a methane fermentation tank 3, and a biological desulfurization treatment tank 4.

  The sulfuric acid reduction reaction tank 2 is connected to a pipe 11 for flowing in wastewater to be treated. Moreover, the sulfuric acid reduction reaction tank 2 and the methane fermentation tank 3 are connected by a pipe 12 for feeding waste water. The upper part of the sulfuric acid reduction reaction tank 2 and the lower part of the biological desulfurization treatment tank 4 are connected by a gas pipe 13 serving as a gas passage. In addition, a pipe 14 is connected to the methane fermentation tank 3 for allowing the drainage to flow into the sewer. The upper part of the methane fermentation tank 3 and the lower part of the biological desulfurization treatment tank 4 are connected by a gas pipe 15 serving as a gas passage. The biological desulfurization treatment tank 4 is connected to a pipe 16 for flowing water used for the reaction and a gas pipe 17 for flowing air. A gas pipe 18 for discharging the generated methane gas is connected to the upper part of the biological desulfurization treatment tank 4. Further, the biological desulfurization treatment tank 4 and the sulfuric acid reduction reaction tank 2 are connected by a pipe 19 for feeding treated water.

  In addition, in the sulfuric acid reduction reaction tank 2, a spherical plastic carrier 202 having a specific gravity of 1.5, to which the sulfuric acid reducing bacteria 201 are attached, as shown in FIG. In the sulfate reduction reaction tank 2, sulfate-reducing bacteria work preferentially, but in addition to sulfate-reducing bacteria, hydrolyzing bacteria, acid-producing bacteria, and the like are included.

  Moreover, in the methane fermentation tank 3, as shown in FIG. 3, granular sludge having a mass of methane producing bacteria as a lump and having a particle diameter of 1 to 10 mm and a sedimentation speed of 1 to 30 m / h is introduced. . In the methane fermenter 3, methanogens work preferentially, but in addition to methanogens, sulfate-reducing bacteria, hydrolyzing bacteria, acid-producing bacteria, and the like are included.

  The sulfuric acid reduction reaction tank 2 and the methane fermentation tank 3 are configured to perform anaerobic treatment using an upflow anaerobic sludge blanket method (UASB). This upward flow anaerobic sludge blanket method is based on the fact that anaerobic microorganisms self-granulate by upward flow to form granular sludge, and the granular sludge is used to increase the concentration in the anaerobic digester. This is a method for efficiently decomposing organic matter in wastewater by maintaining decomposing microorganisms.

  Moreover, in the biological desulfurization treatment tank 4, as shown in FIG. As shown in FIG. 5, the sulfur-oxidizing bacteria adherent carrier 401 is configured such that sulfur-oxidizing bacteria 401B are adhered to the outside or inside of a carrier 401A formed in a cylindrical shape.

  A treatment process when the wastewater to be treated is subjected to organic matter decomposition treatment by biological treatment by the wastewater treatment apparatus 1A according to the present embodiment will be described.

  First, wastewater to be treated is flowed from a pipe 11 connected in the sulfuric acid reduction reaction tank 2, and as shown in the following formula (1), first, macromolecular organic substances (carbohydrates, proteins, lipids) in the wastewater are hydrolyzed. After being decomposed into low molecular organic substances, as shown in the formula (2), the low molecular organic substances are decomposed into lower fatty acids (acetic acid, propionic acid, etc.) by acid producing bacteria.

Furthermore, in the sulfuric acid reduction reaction tank 2, as described later, sulfate ions (SO ₄ ²⁻ ) contained in the sulfuric acid solution (H ₂ SO ₄ (l)) fed from the biological desulfurization treatment tank 4 through the pipe 19 are, Organic substances such as acetic acid are decomposed by being reduced by sulfate-reducing bacteria attached to the plastic carrier 202, and as shown in formula (4), hydrogen sulfide (H ₂ S), carbon dioxide, and water (H ₂ O ) Is generated.

[Chemical 2]
High molecular organic substances (carbohydrates, proteins, lipids) + H ₂ O
→ Low molecular weight organic matter (1)
Low molecular organic matter → Lower fatty acids (acetic acid, propionic acid, etc.) (2)
CH ₃ COOH → CH ₄ + CO ₂ (3)
SO ₄ ²⁻ + CH ₃ COOH + 2H ⁺ → H ₂ S + 2CO ₂ + 2H ₂ O
(4)
H ₂ S + 2O ₂ → SO ₄ ²⁻ + 2H ⁺ (5)
The hydrogen sulfide generated by the reaction of the formula (4) is mainly released into the gas phase as hydrogen sulfide gas (H ₂ S (g)), or is dissociated by the pH of the waste water and sulfide ions (S ^2- ) Released into waste water.

Then, the hydrogen sulfide gas (H ₂ S (g)) released into the gas phase in the sulfuric acid reduction reaction tank 2 is sent to the biological desulfurization treatment tank 4 through the gas pipe 13 and sulfide ions (S ²⁻ ). The waste water containing organic matter that could not be decomposed in the sulfuric acid reduction reaction tank 2 is sent to the methane fermentation tank 3 through the pipe 12.

  In the methane fermentation tank 3, the wastewater that has been subjected to biological treatment with sulfate-reducing bacteria in the sulfuric acid reduction reaction tank 2 and sent is taken in, and the organic matter that could not be decomposed in the sulfuric acid reduction reaction tank 2 is expressed by the above formula (1). After the high-molecular organic substances (carbohydrate, protein, lipid) in the wastewater are decomposed into low-molecular-weight organic substances by hydrolyzing bacteria, the low-molecular-weight organic substances are converted into lower fatty acids (acetic acid, propion by the acid-producing bacteria as shown in formula (2). Acid).

Further, in the methane fermentation tank 3, as shown in the above formula (4), organic substances such as acetic acid are decomposed by sulfate-reducing bacteria in the methane fermentation tank 3, and hydrogen sulfide (H ₂ S), carbon dioxide, and water (H ₂ O) is produced, and lower fatty acids such as acetic acid are converted into methane gas (CH ₄ (g)) and carbon dioxide (CO ₂ ) as shown in the above formula (3) by the granules 301 in the methane fermentation tank 3. And decomposed.

The hydrogen sulfide gas (H ₂ S (g)) generated by the reaction of the formula (4) in the methane fermentation tank 3 and the methane gas (CH ₄ (g)) generated by the reaction of the formula (3) are in the gas phase. The gas is discharged into the biological desulfurization treatment tank 4 through the gas pipe 15.

  Further, the treated waste water in which the organic matter is decomposed in the methane fermentation tank 3 flows out to the sewer through the pipe 14.

Then the biological desulfurization treatment tank 4, the hydrogen sulfide gas delivered from the sulfate reduction reactor 2 and _{(H 2 S (g))} , hydrogen sulfide gas delivered from the methane fermentation tank _{3 (H 2 S (g)} ) And methane gas (CH ₄ (g)) are taken in, water is taken in from the pipe 16, and air for supplying oxygen necessary for desulfurization is taken in from the pipe 17, and sulfur oxidation in the biological desulfurization treatment tank 4 is performed. Desulfurization of hydrogen sulfide (H ₂ S) is performed by the sulfur-oxidizing bacteria 401 B of the bacterial adhesion carrier 401 as shown in the above formula (5), and a sulfuric acid solution (H ₂ SO ₄ ) containing sulfate ions (SO ₄ ²⁻ ). (L)) is generated.

The produced sulfuric acid solution (H ₂ SO ₄ (l)) is sent to the sulfuric acid reduction reaction tank 2 through the pipe 19 and used for the reduction reaction of acetic acid and the like by the sulfuric acid reducing bacteria.

Further, after desulfurization is performed in the biological desulfurization treatment tank 4, the taken-in methane gas (CH ₄ (g)) is discharged from the gas pipe 18.

  According to the first embodiment described above, wastewater treatment is performed by dividing the sulfate-reducing bacteria and methanogenic bacteria that perform organic matter decomposition treatment in an anaerobic treatment environment into a sulfuric acid reduction reaction tank and a methane fermentation tank that each work predominantly. By having comprised so that it may perform, it becomes possible to perform the stable waste water treatment, without reducing the activity of the methane production process by a methanogen.

  At this time, in the sulfate reduction reaction tank where sulfate-reducing bacteria predominate, a plastic carrier that attaches sulfate-reducing bacteria and has a large specific gravity is used. Therefore, the sedimentation rate of this plastic carrier becomes larger than the upward flow rate of the waste water. The sulfate-reducing bacteria can be prevented from flowing out of the tank. Thereby, the processing efficiency of the sulfuric acid reduction process in a sulfuric acid reduction reaction tank is stabilized.

  Also, in the methane fermentation tank where methanogens predominate, granule that is a mass of methanogens and has a large particle size and sedimentation rate is used, so the upward flow rate of the wastewater treated in the sulfuric acid reduction reactor is higher. The sedimentation rate of the granules is increased, and the outflow of methanogens out of the tank can be prevented. Thereby, the process efficiency of the methane fermentation process in a methane fermenter is stabilized.

In addition, in the biological desulfurization treatment tank, since the sulfur-oxidizing bacteria adhesion carrier to which sulfur-oxidizing bacteria are attached is used, hydrogen sulfide gas (H ₂ S (g)) taken from the sulfuric acid reduction reaction tank and the methane fermentation tank and sulfur oxidation are used. The contact efficiency with bacteria increases, and the desulfurization rate can be improved.

  In the present embodiment, the case where the plastic carrier used in the sulfuric acid reduction reaction vessel is spherical has been described. However, the present invention is not limited to this, and other shapes such as a string carrier may be used. In addition to granule, the methanogen used in the methane fermenter can also be used as an inexpensive digested sludge that exists in many sewage treatment plants in Japan. Moreover, although the case where the support | carrier used by the biological desulfurization processing tank was cylindrical was demonstrated, it is not limited to this, You may comprise in another shape.

<< Second Embodiment >>
The configuration of the wastewater treatment apparatus 1B according to the second embodiment of the present invention will be described with reference to FIGS.

As described in the first embodiment, sulfide ions (S ²⁻ ) are dissolved in the wastewater treated in the sulfuric acid reduction reaction tank 2 and the methane fermentation tank 3. ^2- ) inhibits the action of sulfate-reducing bacteria and methanogenic bacteria and delays the reaction rate of these bacteria.

Therefore, in the second embodiment, the wastewater treatment apparatus 1A of the first embodiment is further provided with means for performing sulfur stripping, whereby sulfide ions (S ²⁻ ) dissolved in the wastewater are converted into hydrogen sulfide gas (H ₂ S (g)) is released into the gas phase to increase the reaction efficiency.

As a first means for performing this sulfur stripping, a gas pipe 20 branched from the gas pipe 13 connecting the sulfuric acid reduction reaction tank 2 and the biological desulfurization treatment tank 4 and connected to the sulfuric acid reduction reaction tank 2, and a gas pipe 13 charged from the pump 21 to take in the hydrogen sulfide gas in the gas pipe _{20 (H 2 S (g)} ), the accepted hydrogen sulfide gas in the pump _{21 (H 2 S (g)} ) in the waste water in the sulfate reduction reactor 2 And a diffuser tube 22 that bubbles near the water surface above the plastic carrier.

The hydrogen sulfide gas (H ₂ S (g)) generated in the sulfuric acid reduction reaction tank 2 by the first sulfur stripping means formed in this way passes through the gas pipes 13 and 20 and the sulfuric acid reduction reaction tank 2. By returning to bubbling, sulfide ions (S ²⁻ ) in the waste water are expelled into the gas phase as hydrogen sulfide gas.

  Moreover, as a second means for performing sulfur stripping, a pipe 23 branched from the pipe 12 connecting the sulfuric acid reduction reaction tank 2 and the methane fermentation tank 3 and connected to the sulfuric acid reduction reaction tank 2, and a pipe 12 to the pipe 23 are connected. It has a pump 24 that takes in the waste water, and a watering device 25 that sprinkles the waste water taken in by the pump 24 into the gas phase in the sulfuric acid reduction reaction tank.

By the second sulfur stripping means formed in this way, the wastewater containing sulfide ions (S ²⁻ ) treated in the sulfuric acid reduction reaction tank 2 returns to the sulfuric acid reduction reaction tank 2 through the pipes 12 and 23. By being sprinkled, the sulfide ions (S ²⁻ ) in the wastewater are expelled into the gas phase as hydrogen sulfide gas.

Further, in the methane fermentation tank 3, as in the sulfuric acid reduction reaction tank 2, a gas pipe 26 for returning hydrogen sulfide gas (H ₂ S (g)) into the methane fermentation tank 3, and the treated waste water are supplied to the methane fermentation tank 3. By providing the first and second sulfur stripping means by the pipe 27 or the like for returning to the inside, sulfide ions (S ²⁻ ) in the waste water are expelled into the gas phase as hydrogen sulfide gas.

  Since the treatment in the wastewater treatment apparatus 1B other than the sulfur stripping is the same as the treatment in the wastewater treatment apparatus 1A in the first embodiment, detailed description thereof is omitted.

According to the second embodiment described above, in addition to the effects obtained in the first embodiment, by performing sulfur stripping in the sulfuric acid reduction reaction tank, the sulfur circulation efficiency in the waste water treatment apparatus is increased, and the sulfuric acid reduction reaction tank. Inhibition of the action (biological inhibition) of sulfate-reducing bacteria by sulfide ions (S ²⁻ ) can be prevented, and the efficiency of wastewater treatment can be increased.

In addition, by performing sulfur stripping also in the methane fermentation tank, the sulfur circulation efficiency in the wastewater treatment device is further increased, and the action of methane producing bacteria by sulfide ions (S ²⁻ ) in the methane fermentation tank ( Biological inhibition) can be prevented, and wastewater treatment efficiency can be further increased.

  Further, in the first sulfur stripping means, since the bubbling is performed at a position closer to the water surface above the carrier put in the tank, no disturbance is given to the flow of bacteria, and stable drainage treatment is performed. It can be carried out.

  Further, in the second sulfur stripping means, the sulfur stripping effect can be improved by sprinkling the waste water from a high vapor phase position in the tank.

In the present embodiment, putting back the in the first sulfur stripping means sulfate reduction reactor 2 and the methane fermentation tank 3, hydrogen sulfide gas generated in the respective bath _(H 2 _S (g)) However, bubbling may be performed by injecting a gas such as nitrogen that does not affect water treatment into the sulfuric acid reduction reaction tank 2 and the methane fermentation tank 3.

  In addition, in the first and second sulfur stripping means, an opening / closing valve is provided in each pipe instead of the pump, and by controlling this, gas and waste water are sent to the sulfuric acid reduction reaction tank 2 and the methane fermentation tank 3. It may be.

<< Third Embodiment >>
The configuration of the wastewater treatment apparatus 1C according to the third embodiment of the present invention will be described with reference to FIG.

  The wastewater treatment apparatus 1C according to the present embodiment has a configuration in which an aerobic treatment tank 5 is added downstream of the methane fermentation tank 3 of the wastewater treatment apparatus 1A of the first embodiment or the wastewater treatment apparatus 1B of the second embodiment. Yes.

  Since the processing performed in the sulfuric acid reduction reaction tank 2, the methane fermentation tank 3, and the biological desulfurization processing tank 4 of the wastewater treatment apparatus 1C is the same as that in the first embodiment or the second embodiment, detailed description thereof is omitted. .

  In the aerobic treatment tank 5, aerobic bacteria are introduced, the wastewater treated in the methane fermentation tank 3 is taken in, and the organic matter in the treated wastewater that could not be decomposed is further decomposed by the aerobic bacteria. To do.

  The decomposition process executed in the aerobic treatment tank 5 includes “(Japan) Sewerage Association, Advanced Treatment Facility Design Manual, 1994” and “(Japan) Sewerage Association, Sewerage Maintenance Guidelines, 2003 Edition”. It is conceivable to apply the “activated sludge method”, “anaerobic-aerobic activated sludge method”, “anaerobic-anoxic-aerobic method”, and the like.

  When this “activated sludge method” is applied, organic substances can be removed by aerobic microorganisms.

  In addition, when applying the “membrane separation activated sludge method”, in addition to organic matter removal, the suspended matter (SS) is removed by a microfiltration membrane (MF membrane) installed in the aerobic treatment tank 5, so that It is possible to sufficiently perform solid-liquid separation in the sedimentation basin. In the case of the “anaerobic-aerobic method”, phosphorus can be removed in addition to organic matter removal.

  In addition, when the “anaerobic-anoxic-aerobic method” is applied, it is possible to remove nitrogen and phosphorus in addition to organic matter removal.

  According to the above third embodiment, in addition to the effects obtained in the first embodiment and the second embodiment, the quality of the wastewater can be further improved by the treatment in the aerobic treatment tank. Even when the wastewater treated by the methane fermentation tank does not meet the effluent quality standard, it can be adapted by the treatment of the aerobic treatment tank.

<< 4th Embodiment >>
A configuration of a wastewater treatment apparatus 1D according to the fourth embodiment of the present invention will be described with reference to FIG.

  Since the processing performed in the sulfuric acid reduction reaction tank 2, the methane fermentation tank 3, and the biological desulfurization processing tank 4 of the wastewater treatment apparatus 1D according to the present embodiment is the same as in the first to third embodiments, detailed description thereof is omitted. Description is omitted.

  The wastewater treatment apparatus 1D according to the present embodiment is a methane fermentation tank 3 instead of the pipe 16 that flows water into the biological desulfurization treatment tank 4 of the wastewater treatment apparatus 1A of the first embodiment to the wastewater treatment apparatus 1C of the third embodiment. By connecting a pipe 28 branched from the pipe 14 for draining the wastewater treated in step 1, wastewater supply means for flowing wastewater with high alkalinity into the biological desulfurization treatment tank 4 is added.

  By providing the wastewater supply means in this manner, wastewater with high alkalinity treated in the methane fermentation tank 3 is supplied to the biological desulfurization treatment tank 4 and used for sulfuric acid generation treatment in the biological desulfurization treatment tank 4.

  According to the above 4th Embodiment, in addition to the effect acquired by 1st Embodiment-3rd Embodiment, by performing the desulfurization process in the biological desulfurization processing tank 4 using waste water with high alkalinity, hydrogen sulfide It is possible to increase the gas absorption to accelerate the desulfurization process and further increase the wastewater treatment efficiency.

<< 5th Embodiment >>
A configuration of a wastewater treatment apparatus 1E according to a fifth embodiment of the present invention will be described with reference to FIG.

  The wastewater treatment apparatus 1E according to the present embodiment has a configuration in which a pretreatment tank 6 is added upstream of the sulfuric acid reduction reaction tank 2 of the wastewater treatment apparatus 1A of the first embodiment to the wastewater treatment apparatus 1D of the fourth embodiment. Yes.

  About the process performed in the sulfuric acid reduction reaction tank 2, the methane fermentation tank 3, and the biological desulfurization processing tank 4 of the waste water treatment apparatus 1E, since it is the same as that of 1st Embodiment-4th Embodiment, detailed description is abbreviate | omitted. .

  In the pretreatment tank 6, pretreatment is performed before drainage flows into the sulfuric acid reduction reaction tank 2, and substances that adversely affect the sulfuric acid reduction treatment in the sulfuric acid reduction reaction tank 2 and the methane fermentation treatment in the methane fermentation tank 3 are removed in advance. .

  There are various methods for this pretreatment depending on the quality of raw water. For example, when a lot of sewage and suspended solids (SS) are contained, it is possible to apply filtration using a microfiltration membrane (MF membrane) or ultrafiltration membrane (UF membrane), sand filtration, or the like. Further, when a large amount of protein is contained, heat treatment or the like can be considered.

  When a microfiltration membrane (MF membrane) is used, substances of about 0.1 to 10 (μm) such as suspended substances, bacteria, and ultrafine particles can be removed. Moreover, when it is set as an ultrafiltration membrane (UF membrane), 1-100 (nm) substances, such as protein, oxygen, bacteria, and a virus, can be removed. Moreover, when it is set as sand filtration, the comparatively big suspended | floating matter more than mm order can be removed.

  In the case of heat treatment, the protein in the wastewater can be decomposed by heating it to about 70 (° C.) to solidify it and removing it.

  According to the above fifth embodiment, in addition to the effects obtained in the first to fourth embodiments, by removing in advance a substance that adversely affects the sulfuric acid reduction reaction tank and the methane fermentation tank in the pretreatment tank, It is possible to further increase the wastewater treatment efficiency, particularly the sulfuric acid reduction treatment efficiency in the sulfuric acid reduction reaction tank.

<< 6th Embodiment >>
The configuration of the wastewater treatment apparatus 1F according to the sixth embodiment of the present invention will be described with reference to FIG.

  In the wastewater treatment apparatus 1F according to the present embodiment, sulfur supply means for supplying sulfur from the pipe 29 is added to the sulfuric acid reduction reaction tank 2 of the wastewater treatment apparatus 1A of the first embodiment to the wastewater treatment apparatus 1E of the fifth embodiment. It has a configuration.

  About the process performed in the sulfuric acid reduction reaction tank 2, the methane fermentation tank 3, and the biological desulfurization processing tank 4 of the waste water treatment apparatus 1F, since it is the same as that of 1st Embodiment-5th Embodiment, detailed description is abbreviate | omitted. .

  In the present embodiment, sulfur is supplied from the pipe 29 to the sulfuric acid reduction reaction tank 2 by the sulfur supply means, and is used for the sulfuric acid reduction reaction in the sulfuric acid reduction reaction tank 2.

  According to the sixth embodiment described above, by providing the sulfur supply means for supplying sulfur to the sulfuric acid reduction reaction tank, even if sulfur is not contained in the waste water, the sulfur supply means once provides sulfur. By supplying, sulfur circulation is formed in the waste water treatment apparatus, and efficient waste water treatment can be performed.

DESCRIPTION OF SYMBOLS 1A-1F ... Waste water treatment apparatus 2 ... Sulfuric acid reduction reaction tank 3 ... Methane fermentation tank 4 ... Biological desulfurization treatment tank 5 ... Aerobic treatment tank 6 ... Pretreatment tank 11-20, 23, 26, 27-29 ... Pipe 21 ... Pump 22 ... Air diffuser 24 ... Pump 25 ... Water sprinkler 201 ... Sulfuric acid reducing bacteria 202 ... Plastic carrier 301 ... Granule 401 ... Sulfur oxidizing bacteria adherent carrier 401A ... Carrier 401B ... Sulfur oxidizing bacteria

Claims (8)

Sulfuric acid reduction bacteria are introduced, and the sulfuric acid reduction reaction tank that takes in the wastewater to be treated and performs anaerobic treatment to decompose organic substances by reducing sulfate ions in the wastewater by the sulfuric acid reducing bacteria and generate hydrogen sulfide,
A methane fermentation tank in which methanogenic bacteria are introduced and wastewater treated in the sulfuric acid reduction reaction tank is taken in and anaerobic treatment is performed in which the organic matter in the wastewater that has not been decomposed in the sulfuric acid reduction reaction tank is decomposed by the methanogenic bacteria When,
Sulfur oxidizing bacteria are introduced, hydrogen sulfide generated in the sulfuric acid reduction reaction tank is taken in, sulfuric acid is generated by performing desulfurization treatment with the sulfur oxidizing bacteria, and the generated sulfuric acid is used for the reduction of the sulfate ions A biological desulfurization treatment tank for sending water to the sulfuric acid reduction reaction tank,
A wastewater treatment apparatus comprising: First sulfur stripping means for performing sulfur stripping in the waste water by aeration of the hydrogen sulfide generated in the sulfuric acid reduction reaction tank into the waste water of the sulfuric acid reduction reaction tank;
A second sulfur stripping means for performing sulfur stripping in the waste water by sprinkling the waste water treated in the sulfuric acid reduction reaction tank into the gas phase of the sulfuric acid reduction reaction tank;
The wastewater treatment apparatus according to claim 1, further comprising: Aerobic treatment in which aerobic bacteria are introduced and wastewater treated in the methane fermentation tank is taken in, and organic substances in the wastewater not decomposed in the sulfuric acid reduction reaction tank and the methane fermentation tank are decomposed by the aerobic bacteria. The waste water treatment apparatus according to claim 1, further comprising an aerobic treatment tank for performing the above-described treatment. The wastewater treatment apparatus according to any one of claims 1 to 3, further comprising wastewater supply means for supplying wastewater treated in the methane fermentation tank to the biological desulfurization treatment tank. The wastewater treatment apparatus according to any one of claims 1 to 4, further comprising a filtration means for removing suspended substances or a heat treatment means for decomposing proteins upstream of the sulfuric acid reduction reaction tank. The wastewater treatment apparatus according to any one of claims 1 to 5, further comprising sulfur supply means for supplying sulfur to the sulfuric acid reduction reaction tank. The sulfate reduction reaction tank is loaded with a carrier with sulfate-reducing bacteria attached thereto, the methane fermentation tank is loaded with a mass of methanogenic bacteria, and the biological desulfurization treatment tank is filled with sulfur-oxidizing bacteria attached to the carrier. The waste water treatment apparatus according to claim 1, wherein the waste water treatment apparatus is introduced. Wastewater treatment equipment
The wastewater to be treated is taken into the sulfuric acid reduction reaction tank, and the sulfate ions in the wastewater are reduced by the sulfuric acid reducing bacteria introduced into the sulfuric acid reduction reaction tank to decompose the organic matter and perform anaerobic treatment to generate hydrogen sulfide. ,
An anaerobic treatment in which wastewater treated in the sulfuric acid reduction reaction tank is taken into a methane fermentation tank, and organic matter in the wastewater that has not been decomposed in the sulfuric acid reduction reaction tank is decomposed by the methane-producing bacteria introduced into the methane fermentation tank. And
Hydrogen sulfide produced in the sulfuric acid reduction reaction tank is taken into a biological desulfurization treatment tank, and sulfuric acid is produced by performing desulfurization treatment with sulfur-oxidizing bacteria introduced into the biological desulfurization treatment tank, and the produced sulfuric acid is converted into the sulfuric acid. A wastewater treatment method characterized by sending water to a sulfuric acid reduction reaction tank for use in ion reduction.

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