JP3832888B2 - Purification device operation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving method of the apparatus for removing the waste water from factories and households, and the like.
[0002]
[Prior art]
Waste water from factories and households contains a large amount of high-molecular organic substances such as fat and protein, and if this is washed away into rivers and the sea, it causes environmental pollution. Therefore, a purification apparatus that gasifies and removes nitrogen components and the like through a microorganism decomposition, nitrification, and denitrification process has been known.
[0003]
Here, the treatment with microorganisms is performed in an efficient cycle by repeating an aerobic treatment and an anaerobic treatment.
Ammonium nitrogen in the waste water in the aerobic treatment (NH ₄ ⁺⁾ and nitrate nitrogen (NO ₃ ^-) and nitrite nitrogen (NO ₂ ^-) and oxidative degradation to, and in anaerobic processes, anaerobic denitrifying bacteria Uses organic carbon to reduce nitrate nitrogen (NO ₃ ⁻ ) and nitrite nitrogen (NO ₂ ⁻ ) produced by aerobic treatment and convert them into nitrogen gas (N ₂ ).
In an anaerobic state, macromolecular organic substances such as fat and protein are decomposed into lower molecules such as acetic acid (CH ₃ COOH), and further decomposed into CO ₂ and CH ₄ by methanogens.
[0004]
In order to perform the aerobic treatment and the anaerobic treatment described above, the aerobic treatment and the anaerobic treatment are performed by intermittently performing the aeration operation in one aeration tank and a means for dividing the biological treatment tank into the aerobic treatment tank and the anaerobic treatment tank. There is a means for alternately performing sex treatment, and the former is easy to manage the fungus body, but the apparatus is enlarged and the latter is the opposite.
[0005]
As a guideline for switching the intermittent operation in the aeration tank, in addition to the DO value (dissolved oxygen concentration) and the pH value, a prior biological treatment is performed using the oxidation-reduction potential (ORP) as a control factor for the operation. Technology is known. For example, the above-mentioned JP-A 61-54295, JP-A 62-68594, JP-A 62-163798, JP-A 62-282694, JP-A 62-286597, etc. is there.
[0006]
Incidentally, as described above, a large amount of excess sludge is generated in an apparatus for biologically treating wastewater. Such surplus sludge is generally removed from the sedimentation tank and incinerated, but the processing cost increases. Therefore, Japanese Patent Publication No. 60-3873 proposes a treatment method in which a sludge storage tank is provided and surplus sludge is decomposed and gasified in this sludge storage tank.
[0007]
Further, as prior arts in which sludge is returned from the sludge storage tank to the aeration tank to increase the nitrification efficiency, there are those disclosed in Japanese Patent Application Laid-Open Nos. 61-54295 and 2-284695.
[0008]
[Problems to be solved by the invention]
As mentioned above, when sludge is stored in the sludge storage tank and the sludge is completely gasified in the sludge storage tank, a large amount of sludge cannot be treated, and periodic sludge removal is eliminated. Requires an extremely large sludge storage tank.
[0009]
In addition, if sludge is returned from the sludge storage tank to the aeration tank as a nutrient source for microorganisms, the capacity of the sludge storage tank can be reduced to some extent.
However, a shell-like oxide film is formed on the surface of the sludge, and the sludge cannot be easily decomposed even if it is returned to the aeration tank or the like in this state.
[0010]
The inventor does not easily destroy the oxide film formed on the sludge surface in a normal anaerobic state (reducing atmosphere), but the oxide film is reduced and softened by placing it in a more advanced anaerobic state (super anaerobic state). And gained the knowledge to be destroyed.
[0011]
Then, although it is possible to use the conventional sludge storage tank as a super-anaerobic tank, in order to make a sludge into a super-anaerobic state, it is necessary to leave still for a long period of time. Then, when left standing in a conventional sludge storage tank for a long period of time, there is a possibility that a carry-over may occur.
[0012]
[Means for Solving the Problems]
In order to solve the above problem, the operation method of the purification apparatus according to the present invention is to subject the wastewater to aerobic treatment and anaerobic treatment by microorganisms, solid-liquid separation of the wastewater that has been treated by the microorganisms, And the other part is stored in a super-anaerobic tank that is more anaerobic than the sludge storage tank. It returned to the tank of temper atmosphere .
[0015]
Here, in order to sufficiently destroy the oxide film on the sludge surface, it is preferable to perform a super anaerobic treatment until the oxidation-reduction potential (ORP) of the sludge becomes −190 mV or less, and the sludge in which the shell of the oxide film is broken. For effective aerobic treatment, the DO value (dissolved oxygen content) is preferably 2 ppm or more.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram for carrying out the operation method of the purification apparatus according to the present invention. The purification apparatus is in order from the upstream side: a stock solution tank 1, a flow rate adjustment tank 2, an aeration tank 3, a precipitation tank 4, a sand filter. A tank 5, an activated carbon tank 6 and a disinfection tank 7 are provided, and a sludge storage tank 8 and a super anaerobic tank 9 are further provided downstream of the precipitation tank 4.
[0017]
The stock solution tank 1 is provided with a filter 10 that removes large foreign matters such as wood chips, and waste water that has passed through the filter 10 is sent to the flow rate adjusting tank 2 by the pump 11, and the measuring rod 13 is sent from the flow rate adjusting tank 2 to the pump 12. Waste water is sent to the aeration tank 3 and a certain amount of waste water is supplied to the aeration tank 3 through the measuring tank 13 to perform aerobic treatment and anaerobic treatment.
[0018]
An aeration device 14 and an agitation device 15 are disposed at the bottom of the aeration tank 3, aerobic treatment is performed in the aeration tank 3 by supplying air from the aeration device 14, and aeration is performed by stopping the operation of the aeration device 14. Anaerobic treatment is performed in the tank 3. The agitator 15 is used for quickly switching the inside of the aeration tank to an aerobic atmosphere or an anaerobic atmosphere, and can be operated in both an aerobic treatment and an anaerobic treatment.
[0019]
In addition, the aerobic treatment and the anaerobic treatment in the aeration tank 3 can be switched based on the DO value and pH value of the wastewater in the aeration tank 3, but in order to perform stable treatment, the oxidation-reduction potential (ORP) ) Is preferably used as a reference for switching the operation of the aeration apparatus 14.
[0020]
Then, the waste water after the aerobic treatment and the anaerobic treatment in the aeration tank 3 is sent to the sedimentation tank 4 by the pump 16 and is solid-liquid separated by standing here, and the sludge 17 in the waste water is the sedimentation tank. Precipitate at the bottom of 4.
[0021]
The supernatant liquid in the settling tank 4 is discharged into the sewage or the like through the sand filtration tank 5, the activated carbon tank 6 and the disinfection tank 7 through the quantitative transfer device 18, and one of the sludge 17 that has settled at the bottom of the settling tank 4. The part is returned to the aeration tank 3 by a pump 19 as a nutrient source for microorganisms, and the other part is sent to the sludge storage tank 8 by a pump 20.
[0022]
In the sludge storage tank 8, the sludge 17 is left in an anaerobic state, the supernatant liquid is returned to the flow rate adjustment tank 2 via the quantitative transfer device 21, and a part of the sludge 17 in the sludge storage tank 8 is returned by the pump 25. 23 and the switching valve 24 are returned to the flow rate adjusting tank 2 or the aeration tank 3, and another part is sent to the super anaerobic tank 9 by the pump 22.
[0023]
In the super anaerobic tank 9, the sludge is kept in an anaerobic state until the oxidation-reduction potential (ORP) of sludge becomes −190 mV or less.
When the oxidation-reduction potential (ORP) is −190 mV or less, the surface oxide film 17a of the sludge 17 is sequentially destroyed as shown in FIG. FIG. 2 schematically shows the destruction of the surface oxide film 17a. Actually, the surface oxide film 17a may be thinned and disappear, and these are collectively referred to as destruction.
[0024]
Thus, the sludge 17 whose surface oxide film 17a has been destroyed is returned to the flow rate adjusting tank 2 or the operating aeration tank 3 via the pump 26, the sludge return pipe 23 and the switching valve 24. Since the flow rate adjusting tank 2 is in an aerobic state because waste water flows in, and the aeration tank 3 in the operating state is also in an aerobic state, the sludge 17 in which the surface oxide film 17a is destroyed is the flow rate adjusting tank 2. In the case of returning to, the aeration tank 3 is supplied to the aeration tank 3 in a state where it has been subjected to aerobic treatment to some extent and partially converted into nitrate nitrogen (NO ₃ -N) or nitrite nitrogen (NO ₂ -N). Moreover, when returning to the aeration tank 3, an aerobic process is performed immediately.
[0025]
The supernatant liquid of the super anaerobic tank 9 is returned to the flow rate adjusting tank 2 via the quantitative transfer device 27.
[0026]
FIG. 3 is an overall configuration diagram for carrying out the operation method of the purification apparatus according to another embodiment. In this embodiment, instead of providing one aeration tank as a biological treatment tank, air is constantly introduced. The anaerobic treatment tank 31 and the anaerobic treatment tank 32 in which the introduction of air is completely refused are provided. By adopting such a configuration, it is only necessary to manage the aerobic bacteria in the aerobic treatment tank 31 and only the management of the anaerobic bacteria in the anaerobic treatment tank 32, so the management becomes easy.
[0027]
【The invention's effect】
As described above, according to the present invention, the wastewater is subjected to aerobic treatment and anaerobic treatment with microorganisms in the intermittent aeration tank or aerobic treatment tank, and the wastewater that has been treated with microorganisms in the precipitation tank is solid-liquid separated. A part of the precipitated sludge is stored in the sludge storage tank and the other part is stored in a super anaerobic tank that is more anaerobic than the sludge storage tank, and the surface oxide film is destroyed by the super anaerobic treatment. The sludge was returned to an aerobic atmosphere tank such as an intermittent aeration tank, aerobic treatment tank or flow rate adjustment tank, so aerobic treatment of sludge particles was performed efficiently, and it is necessary to finally collect sludge Therefore, it is possible to provide a purification device that has little or no need.
[0028]
Moreover, even if sludge is allowed to stand for a long time in a super anaerobic tank, a sludge storage tank is provided separately from the super anaerobic tank. .
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram for carrying out a method of operating a purification apparatus according to the present invention. FIG. 2 is a diagram illustrating a state of destruction of a surface oxide film of sludge. Overall configuration diagram for implementing the operation method [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stock solution tank, 2 ... Flow control tank, 3 ... Aeration tank, 4 ... Precipitation tank, 5 ... Filtration tank, 8 ... Sludge storage tank, 9 ... Super-anaerobic tank, 14 ... Aeration apparatus, 15 ... Stirrer, 17 ... Sludge, 17a ... surface oxide film of sludge, 23 ... sludge return pipe, 31 ... aerobic treatment tank, 32 ... anaerobic treatment tank.

Claims (3)

  The wastewater is subjected to aerobic treatment and anaerobic treatment by microorganisms, the wastewater that has been treated by these microorganisms is solid-liquid separated, and a part of the precipitated sludge is stored in the sludge storage tank and the other part is the sludge storage tank. A purifying apparatus characterized in that it is stored in a super anaerobic tank that is more anaerobic than that, and the sludge whose surface oxide film is destroyed by the super anaerobic treatment is returned to the tank in the aerobic atmosphere. how to drive. 2. The operation method of the purification apparatus according to claim 1 , wherein the anaerobic treatment of the sludge is performed until an oxidation-reduction potential (ORP) of the sludge becomes -190 mV or less. The operation method of the purification apparatus according to claim 1 , wherein the aerobic atmosphere tank is an operating aeration tank, an aerobic treatment tank or a flow rate adjustment tank, and a DO value (dissolved oxygen amount) is 2 ppm or more. A method for operating a purification apparatus, comprising:

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