JP7060407B2 - Water treatment equipment and water treatment method - Google Patents

Description

The present invention relates to a water treatment apparatus and a water treatment method. More specifically, the present invention relates to a water treatment apparatus and a water treatment method for treating water to be treated in which a sulfur compound that emits an odor is generated in the process of treatment.

Dimethyl sulfoxide (hereinafter referred to as DMSO) has a high function as a solvent and is used in various industrial fields such as cleaning in the manufacture of semiconductors and liquid crystal panels and spinning of chemical fibers, and is finally discharged as industrial wastewater. Has been done.
Treatment of DMSO-containing wastewater has been carried out by incineration or distillation, but there are many problems such as high treatment costs and air pollution, so it cannot be said to be an effective treatment method. .. On the other hand, as a treatment of DMSO-containing wastewater, a treatment method by an activated sludge method using microorganisms is being studied.

For example, Patent Document 1 describes that DMSO-containing wastewater is treated under aerobic conditions by aeration using a DMSO-conditioned microorganism that is comprehensively fixed in a gel.

Japanese Unexamined Patent Publication No. 7-031991

As in Patent Document 1, when DMSO is treated by biological treatment under aerobic conditions, it is known that it is mineralized through a plurality of decomposition reactions. However, if the reaction rate of any of the decomposition reactions decreases for some reason, methyl sulfide (hereinafter referred to as DMS) and methyl mercaptan (hereinafter referred to as MM), which are intermediate products of the biodegradation reaction of DMSO, are accumulated. There is a problem that a strong odor is generated in the aeration tank.
Further, since the generation of odor and the deterioration of water quality of the treated water are linked, it is required to perform stable treatment of DMSO-containing wastewater without generating odor.

For example, once DMS accumulates in the aeration tank, the decomposition reaction from DMSO to DMS is suppressed, and untreated DMSO flows out into the treated water. However, by reducing the DMS produced from DMSO, the decomposition reaction of DMSO proceeds again, and the water quality of the treated water is improved. As described above, in the treatment of DMSO, deterioration of water quality may occur periodically, and it is required to carry out the treatment so as not to cause the accumulation of DMS, which is a factor of deterioration of water quality.
It is possible to sense the odor of the aeration tank due to the accumulation of DMS by the human sense of smell. However, at this point, a large amount of DMS has already accumulated, resulting in deterioration of water quality.

Therefore, the subject of the present invention is water for preventing deterioration of water quality and enabling stable treatment when treating water to be treated, which generates sulfur compounds that emit odor in the process of treatment, such as DMSO. It is to provide a treatment apparatus and a water treatment method.

As a result of diligent studies on the above problems, the present inventor measured the odor concentration with an odor measuring device when treating the water to be treated, which generates an odor-generating sulfur compound in the process of treatment, and the measured odor concentration. It has been found that by controlling the treatment rate of the water to be treated, the generation of intermediate products that emit odors can be suppressed and stable treatment becomes possible when the amount of water is increasing.
That is, the present invention is the following water treatment apparatus, water treatment system and water treatment method.

The water treatment apparatus of the present invention for solving the above-mentioned problems is a water treatment apparatus for treating water to be treated in which a sulfur compound that emits an odor is generated in the process of treatment, and has an odor measuring unit for detecting the sulfur compound and an odor measuring unit. A control unit for controlling the treatment speed of the water to be treated is provided, and the control unit reduces the treatment speed of the water to be treated or stops the treatment when the value obtained by the odor measuring unit tends to increase. It is characterized by that.

According to this water treatment apparatus, the progress state of the treatment reaction can be determined by observing the increasing / decreasing tendency of the value measured by the odor measuring unit. Here, when the value obtained by the odor measuring unit tends to increase, it is determined that the treatment reaction does not proceed completely and the sulfur compound, which is an intermediate product, is accumulated, and the treatment is performed by the control unit. By reducing the treatment rate of water or stopping the treatment, the formation and accumulation of intermediate products can be suppressed. This enables stable processing of the entire processing system.

Further, one embodiment of the water treatment system of the present invention is characterized in that the control unit controls to reduce the treatment speed of the water to be treated or to release the treatment stop.
According to this feature, by reducing or stopping the treatment of the water to be treated, the generation and accumulation of intermediate products are suppressed to a predetermined amount or less, and then the control unit controls the treatment speed of the water to be treated again. The processing efficiency can be restored by canceling the decrease or the processing stop.

Further, the water treatment method of the present invention is a water treatment method for treating water to be treated in which a sulfur compound that emits an odor is generated in the process of treatment, and is an odor measuring step for detecting the sulfur compound and treatment of the water to be treated. A control step for controlling the speed is provided, and when the value obtained in the odor measuring step tends to increase, the treatment speed of the water to be treated is reduced or the treatment is stopped in the control step.
According to this water treatment method, when the value detected in the odor measurement step tends to increase, it is determined that the sulfur compound, which is an intermediate product in the treatment process, has accumulated, and the water to be treated is controlled by the control step. By reducing the processing speed or stopping the processing, it is possible to suppress the generation and accumulation of intermediate products. This has the effect of stabilizing the treated water quality.

According to the present invention, when treating water to be treated in which a sulfur compound that emits odor is generated in the process of treatment, the odor concentration is measured by an odor measuring device, and the measured odor concentration tends to increase. By controlling the treatment rate of treated water, it is possible to provide a water treatment device and a water treatment method for suppressing the generation of intermediate products that emit odor, preventing deterioration of water quality, and enabling stable treatment. can.
Further, the present invention can be particularly suitably used for water treatment including a plurality of decomposition steps, such as biological treatment of DMSO-containing wastewater.

It is a schematic diagram which shows the structure of the water treatment apparatus of 1st Embodiment of this invention. It is an image diagram of the measurement result of the odor measuring part in the water treatment apparatus of 1st Embodiment of this invention. It is a figure which shows the control flow of the water treatment apparatus of 1st Embodiment of this invention. It is an image diagram of the measurement result of the odor measuring part in the water treatment apparatus of the 2nd Embodiment of this invention. It is a figure which shows the control flow of the water treatment apparatus of the 2nd Embodiment of this invention.

The water treatment apparatus of the present invention is intended to be used for biological treatment of water to be treated, in which sulfur compounds that emit odors are generated in the process of treatment.

The type of water to be treated by the water treatment apparatus of the present invention is not particularly limited as long as it is water to be treated that generates a sulfur compound that emits an odor in the process of treatment, but it is particularly preferable to target DMSO-containing wastewater. ..
Hereinafter, a case where the water to be treated is DMSO-containing wastewater will be described.

It is known that when DMSO-containing wastewater is subjected to biological treatment by microorganisms, the biodegradation reaction as shown below proceeds and is decomposed into hydrogen sulfide and sulfuric acid as intermediate products via DMS and MM. ..
(CH ₃ ) ₂ SO → (CH ₃ ) ₂ S → CH ₃ SH → H ₂ S → H ₂ SO ₄
(DMSO) (DMS) (MM) (Hydrogen Sulfide) (Sulfuric Acid)

Here, DMS and MM, which are intermediate products of the biodegradation reaction of DMSO, are odorous substances and are the objects of odor measurement in the present invention.

In the above biodegradation reaction, it is considered that the decomposition rate from DMS to MM is lower than the decomposition rate from DMSO to DMS. Therefore, if DMSO is continuously supplied in a constant amount, the amount of DMS produced is larger than the amount of DMS being produced due to the progress of the decomposition reaction of DMS, and the accumulation of DMS occurs. As a result, the decomposition reaction from DMS to MM becomes the rate-determining step, and even if DMSO is continuously supplied, the decomposition reaction from DMSO to DMS does not proceed, which leads to deterioration of the treated water quality.

In the water treatment apparatus of the present invention, the progress state of the biodegradation reaction of DMSO can be determined by measuring the concentration of DMS or MM, which is an odorous substance, and observing the increasing / decreasing tendency of the measured value. Here, when the value of the concentration of the obtained odorous substance tends to increase, it is determined that the biodegradation reaction of DMSO has not completely proceeded and the accumulation of DMS, which is an intermediate product, has occurred.
At this time, by controlling the supply of the water to be treated to the water treatment apparatus to be reduced or stopped, the treatment rate of the water to be treated (decomposition reaction rate from DMSO to DMS) can be reduced or the treatment can be stopped. It is possible to suppress the generation and accumulation of DMS. This enables stable treatment of DMSO-containing wastewater.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The water treatment method of the present invention shall be replaced with the following description of the configuration and operation of the water treatment device. Moreover, this embodiment does not limit the present invention.

[First Embodiment]
FIG. 1 is a schematic view showing the configuration of the water treatment apparatus according to the first embodiment of the present invention.
The water treatment apparatus 1 of the present embodiment treats the water to be treated W in which a sulfur compound that emits an odor is generated in the process of treatment, and as shown in FIG. 1, the raw water tank 2 and the biological treatment tank 3 , The odor measuring unit 4, the control unit 5, and the lines L1 to L4 are provided.

The raw water tank 2 is a tank for storing the treated water W discharged from various factories and the like, and includes a raw water supply pump 21 for controlling the supply amount of the treated water W on the line L2 on the downstream side.
The raw water supply pump 21 is connected so as to enable drive control by the control unit 5, which will be described later, and changes the supply amount of the water to be treated W to the biological treatment tank 3 by a signal from the control unit 5. Is.

The water to be treated W stored in the raw water tank 21 is supplied to the biological treatment tank 3 via the raw water supply pump 21 and the line L2.

The biological treatment tank 3 is a tank for treating the water to be treated W with activated sludge under aerobic conditions, and includes an aeration tank 31 and an aeration blower B.
The aeration blower B is not particularly limited as long as it is for making the inside of the aeration tank 31 aerobic conditions. For example, it may be an air diffuser connected to a plurality of nozzles, or it may be a microbubble supply device that supplies microbubbles that are bubbles of 100 μm or less. In particular, by using the micro-bubble supply device, the activity of the sulfur-oxidizing bacteria in the biological treatment tank 3 is increased, and the physical oxidation is promoted, so that the treatment can be performed in a short time. This makes it possible to effectively treat hydrogen sulfide and the like produced by the biodegradation reaction.
As the biological treatment tank 3, a known aerobic treatment tank can be used. For example, microorganisms acclimatized to the treatment target may be added to the activated sludge, or a plurality of aeration tanks may be provided.
Further, the biological treatment tank 3 may be provided with ancillary equipment such as a stirring device for stirring the water to be treated in the tank and a chemical addition device for adding a chemical such as a pH adjuster.

The treated water W1 treated in the biological treatment tank 3 is discharged through the line L3.
In addition, other water treatment equipment such as a solid-liquid separation equipment may be provided after the biological treatment tank 3. Examples of the solid-liquid separation equipment include a membrane separation tank and a coagulation sedimentation tank. This makes it possible to separate and treat the excess sludge and the treated water generated in the biological treatment tank 3. At this time, the separated excess sludge may be returned to the biological treatment tank 3.
Further, the other water treatment equipment provided after the biological treatment tank 3 is not limited to the solid-liquid separation equipment. For example, it may be provided with a water treatment facility for treating the substance to be treated existing in the water to be treated W. This makes it possible to improve the treatment efficiency of the entire water treatment device.

The odor measuring unit 4 is for measuring the odorous substance (sulfur compound) contained in the gas G generated in the biological treatment tank 3, and as shown in FIG. 1, the odor sensor 41 is used in the biological treatment tank 3. It is provided on the line L4 connected to. Further, as shown in FIG. 1, a deodorizing fan F may be provided in the line L4 to draw the gas G generated in the biological treatment tank 3 into the line L4 and at the same time treat and discharge the gas G.
Further, the odor measuring unit 4 is provided with a timer T1 and measures the odor at predetermined time (sampling interval) set by the timer T1, and the measurement result is input to the control unit 5.
The odor sensor 41 may be any as long as it can detect the sulfur compound with a sensitivity at least higher than that of the human sense of smell and can send the measurement result as an electric signal to the control unit 5. For example, an indium-based heat ray type sintered semiconductor sensor, a tin-based heat ray type sintered semiconductor sensor, and the like can be mentioned.

The control unit 5 is for controlling the treatment speed of the water to be treated W based on the measurement result of the odor measurement unit 4. As shown in FIG. 1, the control unit 5 records the measurement results input from the odor measurement unit 4 and analyzes them as changes over time, and the control unit 5 from the raw water tank 2 based on the analysis results of the analysis unit 51. In order to control the amount of raw water supplied, a drive unit 52 for driving the raw water supply pump 21 is provided.
When the analysis unit 51 determines that the value obtained by the odor measuring unit 4 tends to increase, the raw water supply pump 21 is driven via the driving unit 52 so that the raw water supply amount decreases.
Further, the control unit 5 is provided with a timer T2, and after a predetermined time has elapsed, the raw water supply pump 21 is driven again to control the raw water supply amount to be restored.

FIG. 2 is an image diagram showing changes over time in the concentration of odorous substances measured by the odor measuring unit of the water treatment apparatus of the present embodiment. Further, FIG. 3 shows a control flow of the water treatment apparatus of this embodiment.

In the water treatment apparatus of the present embodiment, as shown in FIG. 2, the value of the slope of the graph when the odorous substance concentration S measured by the odor measuring unit 4 is plotted against the time t, that is, the odorous substance concentration S. The amount of change (ΔS / Δt) obtained by differentiating the change with time is used as a parameter.

As shown in FIG. 3, in the control flow in the water treatment apparatus of the present embodiment, first, the odor substance concentration S is measured by the odor measuring unit 4 (step 1). In the analysis unit 51 of the control unit 5, the change amount (ΔS / Δt) of the odorous substance concentration S with respect to time t is obtained by differentiating the change with time of the measured value (step 2). When it is determined that the amount of change in the odorous substance concentration S becomes a positive value and exceeds a predetermined value, the control unit 5 limits the amount of raw water supply to 1/2 (step 3-1). If the amount of change in the odorous substance concentration S does not exceed a predetermined value or becomes zero or a negative value, the process returns to step 1 after the predetermined time set by the timer T1 elapses, and the odorous substance concentration S is measured. (Step 3-2). On the other hand, after step 3-1 and after a predetermined time set by the timer T2 elapses, the control unit 5 releases the restriction on the amount of raw water supplied and returns to step 1 (step 4).

If the biodegradation reaction of DMSO is proceeding without any problem according to the above control flow, steps 1, 2 and 3-2 are circulated. On the other hand, when any of the decomposition reaction rates in the biodegradation reaction of DMSO decreases, the process proceeds from step 1 and step 2 to step 3-1 to reduce the supply amount of DMSO and reduce the processing rate of DMSO. This makes it possible to create an environment in which the decomposition reaction of DMS easily proceeds. After that, the process proceeds to step 4, and after securing the time set by the timer T2, that is, the time sufficient for the decomposition reaction of DMS to proceed, the supply amount of DMSO is restored. This enables stable processing of the entire system.

Further, in the water treatment apparatus of the first embodiment, assuming a time when the amount of water to be treated is small, the odor in the water treatment apparatus may hardly be generated due to the suspension of raw water supply for one day or the like. When the raw water supply is started under this condition, the value of the odorous substance concentration S starts from the vicinity of zero, so that the amount of change in the odorous substance concentration S may increase sharply. In this case, when the water treatment apparatus is started, the operation via steps 3-1 and 4 in the control flow frequently occurs, and the control flow may not converge due to repeated starting and stopping.
Therefore, an absolute threshold value is set as the odorous substance concentration S, and as step 1, a step of comparing the measured odorous substance concentration S value with the set threshold value is added, and the case where the odorous substance concentration S value is equal to or less than the threshold value. , The process may be continued without performing the following control flow, and when the value of the odorous substance concentration S exceeds the threshold value, the control flow after step 2 may be advanced.

[Second Embodiment]
The water treatment apparatus of the second embodiment controls by changing the parameters used in the control unit 5 of the first embodiment. The configuration of the device is the same as that of the water treatment device of the first embodiment.

FIG. 4 is an image diagram showing changes over time in the amount of change in the concentration of odorous substances used in the control unit of the water treatment apparatus of the present embodiment. Further, FIG. 5 shows a control flow of the water treatment apparatus of this embodiment.

In the water treatment apparatus of the present embodiment, as shown in FIG. 4, the amount of change in the odorous substance concentration S (ΔS ₁ / Δt ₁ ) is compared with the previous result (ΔS ₀ / Δt ₀ ). This is for determining the tendency of DMS accumulation in the biological treatment tank 3. If ΔS ₁ / Δt ₁ is larger than or has the same value as ΔS ₀ / Δt ₀ , it is determined that DMS accumulation has occurred.

As shown in FIG. 5, in the control flow in the water treatment apparatus of the present embodiment, first, the odor substance concentration S is measured by the odor measuring unit 4 (step 1). In the analysis unit 51 of the control unit 5, the amount of change in the odorous substance concentration S (ΔS ₁ / Δt ₁ ) is obtained and compared with the previous value (ΔS ₀ / Δt ₀ ) (step 2). When ΔS ₁ / Δt ₁ is larger than ΔS ₀ / Δt ₀ , the control unit 5 stops the raw water supply (step 3-1). If ΔS ₁ / Δt ₁ is smaller than or has the same value as ΔS ₀ / Δt ₀ , the process returns to step 1 after a predetermined time set by the timer T1 elapses, and the odorous substance concentration S is measured (step). 3-2). On the other hand, after the lapse of a predetermined time set by the timer T1 after step 3-1 the odor substance concentration S is measured by the odor measuring unit 4 to obtain the amount of change (ΔS ₂ / Δt ₂ ) in the odor substance concentration S (ΔS 2 / Δt 2). Step 4). If ΔS ₂ / Δt ₂ is larger than or equal to ΔS ₁ / Δt ₁ , the process returns to step 3-1 and the raw water supply is continuously stopped. On the other hand, when ΔS ₂ / Δt ₂ is smaller than ΔS ₁ / Δt ₁ , the control unit 5 releases the suspension of the raw water supply and returns to step 1 (step 5).

When the process proceeds from step 3-1 to step 4 and then returns to step 3-1 the change amount (ΔS _n / Δt _n ) of the odorous substance concentration S measured in the next step 4 is the previous step. Steps 4 and 3-1 are repeated until the change amount (ΔS _n-1 / Δt _n-1 ) of the odorous substance concentration S measured in 4 becomes smaller than the value.

If the biodegradation reaction of DMSO is proceeding without any problem according to the above control flow, steps 1, 2 and 3-2 are circulated. On the other hand, when any of the decomposition reaction rates decreases in the biodegradation reaction of DMSO, the process proceeds from step 1 and step 2 to step 3-1 to stop the supply of DMSO and set the processing speed of DMSO to zero. This makes it possible to create an environment in which the decomposition reaction of DMS easily proceeds. Then, the process proceeds to step 4, and after the time set by the timer T1, the odorous substance concentration S is measured again, and it is determined whether the amount of change in the odorous substance concentration S tends to increase or decrease. As a result, when the amount of change in the odorous substance concentration S is reduced and it is determined that the decomposition reaction of DMS has sufficiently proceeded, the process proceeds to step 5 to restore the supply amount of DMSO. On the other hand, if the amount of change in the odorous substance concentration S tends to increase or does not change, it is determined that the accumulation of DMS has not been eliminated, and the supply of DMSO is continuously stopped.
As a result, the accumulation state of DMS in the biological treatment tank 3 can be grasped more accurately, the DMSO processing is not restarted while the DMS is accumulated in the system, and the DMS in the system is already accumulated. It is possible to avoid the situation where the DMSO processing is continuously stopped even though the problem has been solved.

The above-described embodiment shows an example of a water treatment device. The water treatment apparatus according to the present invention is not limited to the above-described embodiment, and the water treatment apparatus according to the above-described embodiment may be modified without changing the gist described in the claims.

For example, in the water treatment apparatus of the present embodiment, in the determination that the value obtained by the odor measuring unit tends to increase, another analysis using the change amount of the odor substance concentration and the change amount of the odor substance concentration are not included. The analysis may be performed using another parameter of.

Further, the water treatment device in the present embodiment may be provided with an advanced treatment device for treating the treated water in the subsequent stage. The advanced treatment device may be any device for treating substances that cannot be completely treated by biological treatment, and examples thereof include an activated carbon adsorption tower and a chelate adsorption tower for collecting heavy metals.

The water treatment apparatus and water treatment method of the present invention can be used for treating water to be treated in which sulfur compounds that emit odors are generated in the process of treatment. For example, it is suitably used for biological treatment of wastewater containing DMSO.

1 ... Water treatment system, 2 ... Raw water tank, 3 ... Biological treatment tank, 4 ... Odor measurement unit, 5 ... Control unit, 21 ... Raw water supply pump, 31 ... Aeration tank, 41 ... Odor sensor, 51 ... Analysis unit, 52 ... Drive unit, B ... Aeration blower, F ... Deodorizing fan, G ... Gas, L1 to L4 ... Line, T1, T2 ... Timer, W ... Treated water, W1 ... Treated water

Claims (3)

A water treatment device that treats water to be treated, which generates odorous sulfur compounds in the process of treatment.
Biological treatment tank and
An odor measuring unit that detects sulfur compounds,
It is equipped with a control unit that controls the treatment speed of the water to be treated.
The control unit is characterized in that the supply of water to be treated to the biological treatment tank is reduced or stopped based on the amount of change in the concentration of the odorous substance obtained by the odor measuring unit. Water treatment equipment. The water treatment apparatus according to claim 1, wherein the control unit controls to reduce the supply of the water to be treated to the biological treatment tank or cancel the supply suspension. It is a water treatment method for treating water to be treated, which generates odorous sulfur compounds in the process of treatment.
Odor measurement process to detect sulfur compounds and
It is equipped with a control process that controls the treatment speed of the water to be treated.
Water treatment, which is characterized in that the supply of water to be treated to the biological treatment tank is reduced or stopped in the control step based on the amount of change in the concentration of the odorous substance obtained in the odor measurement step. Method.

Images