JP3388293B2 - Biological nitrification and denitrification method for night soil - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological nitrification / denitrification treatment method for wastewater such as human waste, sewage, garbage, industrial wastewater and the like, and more particularly to nitrification under aerobic conditions in a single tank. By alternately repeating the process and the denitrification process under anaerobic conditions, nitrogen, phosphorus, etc. are removed from the sewage.

[0002]

2. Description of the Related Art Conventionally, when a nitrification process and a denitrification process are alternately performed in a single tank, both processes include an ORP (oxidation-reduction potential) meter and a DO (dissolved oxygen concentration) meter installed in the single tank. It was performed by making a comprehensive judgment of each measured value using a pH meter and the like.

[0003]

However, the above-mentioned O
When comprehensively determining RP, DO, pH, etc., each of the above measured values will change in the nitrification process and the denitrification process as the property of the inflowing sewage changes. It is practically difficult to make such a judgment and to appropriately advance both strokes at all times, and therefore, the nitrification and denitrification treatment is not performed efficiently.

The object of the present invention is to carry out the nitrification process and the denitrification process alternately in a single tank, based on one clear criterion, that is, the ORP (oxidation-reduction potential) inflection point, and to perform both processes at all times. It is an object of the present invention to provide a biological nitrification denitrification treatment method that can be appropriately advanced and can easily follow changes in the properties of inflowing wastewater.

[0005]

The present invention provides a single nitrification denitrification.
Allowed to flow into sewage human waste such as nitrogen tank, alternating rows that have a denitrification process by stirring the nitrification process by aeration, by the time ratio of the nitrification process and de窒行in a batch constant, de wastewater A biological nitrification / denitrification treatment method in which a nitrogen is introduced into a nitrification process , which is measured at a predetermined time in a nitrification / denitrification tank.
The ORP inflection point is detected from the RP (redox potential) value, and
The ORP inflection point appears 5 minutes before the start of the conversion process
In this case, increase the aeration volume and make the ORP inflection point appear.
If the nitrification process has started, reduce the aeration air volume.
Also, from 5 minutes before the nitrification process starts to immediately before
If the ORP inflection point appears, change the aeration volume
It is characterized in to Rukoto so as not.

That is, according to the present invention, the time for the nitrification process and the denitrification process are set to a fixed time in advance, and the ORP value increases in the nitrification process during the determined one cycle time, and the denitrification process is performed. In the denitrification process, paying attention to the fact that the ORP value decreases in the process, before the start of the next nitrification process, O
By increasing or decreasing the amount of aeration air so that the RP inflection point appears, efficient nitrification denitrification is possible.

From the standpoint of treatment efficiency, the increase or decrease in the amount of aeration air causes the ORP from 5 minutes before the nitrification process starts to immediately before it.
And performs as the inflection point appears.

Further, in the present invention, the inflow timing and inflow time of the sewage in the denitrification process are not particularly limited, and the sewage may be allowed to continuously flow in during the denitrification process, or only at a certain time in the denitrification process. Although it may be allowed to flow in only for a limited period of time, it is preferable from the viewpoint of treatment efficiency that the flow is carried out in a short time of about 5 minutes from the start of the denitrification process.

Further , according to the present invention, the increase / decrease of the aeration air volume is calculated by OR.
ORP value at a predetermined time in the nitrification denitrification tank by P meter
Is measured and the ORP value output (voltage, current, etc.
Value) is A / D converted by an A / D converter, and the
Change amount (ΔP) of the rule value (P), and the change amount (ΔP)
And the elapsed time (t) after the start of the denitrification process is entered, and nitrification is performed.
The ORP inflection point is present between 5 minutes before and immediately before the start of the process.
If the aeration amount is not changed, the nitrification process
If the ORP inflection point appears 5 minutes before the start,
The nitrification process has started without the ORP inflection point appearing.
If the ORP inflection point appears, after the denitrification process starts
Corresponding to the elapsed time (t) of the
Calculate the increase / decrease value (ΔQ) from the
In addition to the standard aeration volume (Q0), the optimum aeration volume (Q)
And the aeration air volume command value (A
Output as the analog value), and based on this, the ejector
It is characterized by automatically controlling the air volume of blowers and blowers.
It In the present specification, one batch means one batch of treating a fixed amount of wastewater, and one cycle means one combination of a nitrification process and a denitrification process. And usually 1
The batch processing is performed in one cycle, but the one batch processing may be performed in a plurality of cycles.

The time for one batch is preferably in the range of 20 minutes to 6 hours. When it is shorter than 20 minutes, sufficient nitrification denitrification cannot be performed in time, and when it exceeds 6 hours, it takes a long time to complete the nitrification denitrification, and the treatment efficiency is extremely low. Because it will be. Further, in order to perform sufficient nitrification and denitrification and maintain the treatment efficiency to some extent high, the time for one batch is preferably set within the range of 0.5 to 2 hours. Moreover, since the denitrification process usually takes longer than the nitrification process, the time for the denitrification process in one cycle should be equal to or longer than the time for the nitrification process.

In the present invention, the nitrification denitrification treatment in a single tank is a principle, but the treatment liquid discharged from the single tank is caused to flow into the secondary tank as necessary to perform the secondary nitrification denitrification. Sometimes.

As described above, the ORP (oxidation-reduction potential) value increases in the nitrification process and decreases in the denitrification process. However, the present invention is based on the ORP at the end of the denitrification process.
Since the amount of aeration air is increased / decreased with the inflection point as the only criterion, the nitrification process is started after a sufficient denitrification process is performed within one preset batch time. Efficient nitrification and denitrification is possible, and when the aeration air volume is increased or decreased so that the ORP inflection point appears between 5 minutes before and immediately before the start of the nitrification stroke, sufficient denitrification stroke is performed. After that, the nitrification process is started immediately, which enables more efficient nitrification and denitrification.

The ORP inflection point is usually recognized when the ORP value starts to suddenly decrease at the end of the denitrification process.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1] FIG. 1 is a flow sheet of the present embodiment, in which (1) is a single nitrification and denitrification tank, and (2) is a solid-liquid of treated water discharged from the nitrification and denitrification tank (1). Separation equipment, (3) is a coagulation sedimentation tank for injecting a coagulant into the separation liquid from the solid-liquid separation equipment (2) to obtain clear treated water by precipitation or floating separation, and (4) is an aggregation sedimentation tank (3 It is a sludge treatment facility that processes coagulation sludge from the bottom part of) and excess sludge from the solid-liquid separator (2). In addition, solid-liquid separator
Part of the sludge discharged from (2) is supplied to the nitrification denitrification tank (1) as return sludge.

FIG. 2 is an enlarged view of the nitrification denitrification tank (1). The nitrification denitrification tank (1) has an ORP (oxidation-reduction potential) meter.
(5), a DO meter (6) and a pH meter (7) are attached, and an ejector (8) for supplying air or oxygen is provided on the side of the nitrification denitrification tank (1). Then, air or the like is supplied at the time of aeration, and the supply of air or the like is stopped at the time of stirring, but a small amount of air may be supplied at the time of stirring in order to improve stirring efficiency.

In addition to the above, the nitrification denitrification tank (1) has an input pipe (9) for returning sludge or concentrated sludge and an inflow pipe (1) for sewage such as human waste.
1) and a discharge line (12) are provided.

In FIG. 3, instead of the ejector (8),
An underwater stirrer (13) is arranged at the bottom of the nitrification denitrification tank (1). The stirrer (13) stirs the inside of the tank, and aeration is performed by air supply by a blower (not shown). It is done like this.

Next, a method for treating wastewater containing human waste and septic tank sludge at a ratio of 8: 2 using each of the above-mentioned devices will be described. First, in the nitrification denitrification tank (1),
When injecting sewage and alternately performing the nitrification process by aeration and the denitrification process by stirring, the time for the nitrification denitrification process of 1 batch 1 cycle is set in advance to 1 hour.
5 minutes is a nitrification step, and the remaining 45 minutes is a denitrification step.
In addition, sewage is allowed to flow in within 5 minutes from the start of the denitrification process.

Table 1 shows the sewage containing human waste and septic tank sludge.
1 minute in nitrification and denitrification tank (1) for biological nitrification and denitrification
PH value, DO (dissolved oxygen concentration) value,
And ORP (oxidation-reduction potential) values. That
Fig. 4 shows the change of ORP value in the nitrification denitrification tank (1).
It is a graph which shows. These FIG. 4 graphs and Table 1
As shown in Figure 5, when sewage is introduced for 5 minutes from the start of the denitrification process in the nitrification denitrification tank (1), the ORP value is about 130.
After a rapid drop from mV to around 0 mV, followed by a slow decline, 5 minutes before the end of the denitrification process, the ORP inflection point (C)
Appears . In this embodiment, 40 times after the start of the denitrification process
The ORP value after the lapse of minutes is -34 mV, and the next 41 minutes
The ORP value after the passage is -170 mV, and changes greatly here.
And the ORP inflection point (C) appears. And O
It rapidly drops near the RP inflection point (C) , and drops to about -260 mV at the end of the denitrification process. During this period, nitrite nitrogen and nitrate nitrogen were converted to nitrogen gas and removed, and the DO at this time was 0 mg / l.

Next, when the nitrification process is started, the ORP value again rapidly rises to around 130 mV, and gradually increases before the end of the nitrification process. In this case, DO is 1 mg /
1 or more, ammoniacal nitrogen is removed, and nitrite nitrogen and nitrate nitrogen increase.

[0022]

[Table 1] As described above, in the present embodiment, the nitrification process starts for 4 minutes.
The ORP inflection point (C) has appeared in front . In this embodiment,
Thus, in the nitrification and denitrification tank (1), OR is performed every 1 minute.
The P (oxidation-reduction potential) value is measured, and the aeration volume is increased or decreased so that the ORP inflection point (C) appears between 5 minutes before and immediately before the start of the nitrification process.

Specifically , 1 minute in the nitrification denitrification tank (1)
ORP (oxidation-reduction potential) values measured every interval
Detecting the inflection point (C), as shown in the graph of FIG. 5, when the ORP inflection point until 5 minutes before the nitrification process begins (C) has appeared increases the aeration air quantity, and FIG. As shown in the graph of 6 , when the nitrification process has started without the ORP inflection point (C) appearing, the aeration air volume is reduced. Further, as shown in the graph of FIG. 4 , when the ORP inflection point (C) appears between 5 minutes before and immediately before the start of the nitrification process, the aeration air volume is not changed.

[0024] Adjustment of 曝 air flow rate, as shown in FIG. 7, O
For example, every 1 minute in the nitrification and denitrification tank (1) by RP meter
Etc., the ORP value is measured every predetermined time, and the output (analog value of voltage, current, etc.) of the ORP value is A / D converted by an A / D converter, and the digital value (P) Amount of change (Δ
P) is obtained, and the change amount (ΔP) and the elapsed time (t) after the start of the denitrification process are input . And shown in the graph of Figure 4.
As you can see, 5 minutes before the start of the nitrification process-just before
If the RP inflection point (C) appears, change the aeration air volume.
No, but as shown in the graph in Figure 5, the nitrification process begins.
If the ORP inflection point (C) appears 5 minutes before,
As shown in the graph of 6, the ORP inflection point (C) appears.
If the nitrification process has started, the ORP inflection
At the elapsed time (t) after the start of the denitrification process where point (C) appears
Correspondingly, increase / decrease value (ΔQ) by aeration air volume increase / decrease value calculator
Is calculated, and the increase / decrease value (ΔQ) is used as the reference aeration air volume (Q
In addition to 0), and optimum aeration air flow rate (Q), which the D /
It outputs as an aeration air volume command value (analog value) via the A converter, and automatically controls the air volume of the ejector (8) and the blower based on this.

[Embodiment 2] As shown in FIG. 8, in this embodiment, after nitrifying and denitrifying treatment is performed by the same nitrifying and denitrifying tank (1) as in Embodiment 1, the secondary nitrifying and denitrifying tank is further processed. By (21), secondary nitrification and denitrification treatment is performed. In the secondary nitrification and denitrification tank (21), first, aeration (nitrification) is carried out by air feeding, then denitrification is carried out by stirring while injecting alcohol, and finally the alcohol content is skipped by air feeding. It is a thing.

Since the present embodiment is the same as the first embodiment except for the treatment by the secondary nitrification and denitrification tank (21), the description will be given with the same reference numerals as in the first embodiment in FIG. Omit it.

[0027]

INDUSTRIAL APPLICABILITY As described above, the present invention is a single nitrification denitrification.
Allowed to flow into sewage human waste such as nitrogen tank, alternating rows that have a denitrification process by stirring the nitrification process by aeration, by the time ratio of the nitrification process and de窒行in a batch constant, de wastewater A biological nitrification / denitrification treatment method in which a nitrogen is introduced into a nitrification process , which is measured at a predetermined time in a nitrification / denitrification tank.
The ORP inflection point is detected from the RP (redox potential) value, and
The ORP inflection point appears 5 minutes before the start of the conversion process
In this case, increase the aeration volume and make the ORP inflection point appear.
If the nitrification process has started, reduce the aeration air volume.
Also, from 5 minutes before the nitrification process starts to immediately before
If the ORP inflection point appears, change the aeration volume
There is no way in you shall, ORP at the end of the more de-窒行
With the inflection point as the only criterion, the amount of aeration air is increased or decreased so that the inflection point appears before the next nitrification process starts. Therefore, a sufficient denitrification process can be performed within one preset batch time. After that, the nitrification process is started, which enables efficient nitrification and denitrification, and changes in the amount of aeration air can be changed from 5 minutes before the start of the nitrification process to immediately before. When the process is performed so that dots appear, the nitrification process is started immediately after a sufficient denitrification process is performed, so that more efficient nitrification denitrification is possible. Moreover, since there is no ambiguity as in the case of comprehensively judging the ORP value, the DO value and the pH as in the conventional case, the nitrification process and the denitrification process in a single tank can be performed based on an appropriate judgment. It can be carried out appropriately and easily by following changes in the properties of inflowing sewage.

In addition, the nitrification process under aerobic conditions and the denitrification process under anaerobic conditions are alternately and efficiently performed to remove phosphorus contained in wastewater such as human waste. Will be done promptly.

Further, according to the present invention, the increase / decrease of the aeration amount is calculated by OR
ORP value at a predetermined time in the nitrification denitrification tank by P meter
Is measured and the ORP value output (voltage, current, etc.
Value) is A / D converted by an A / D converter, and the
Change amount (ΔP) of the rule value (P), and the change amount (ΔP)
And the elapsed time (t) after the start of the denitrification process is entered, and nitrification is performed.
The ORP inflection point is present between 5 minutes before and immediately before the start of the process.
If the aeration amount is not changed, the nitrification process
If the ORP inflection point appears 5 minutes before the start,
The nitrification process has started without the ORP inflection point appearing.
If the ORP inflection point appears, after the denitrification process starts
Corresponding to the elapsed time (t) of the
Calculate the increase / decrease value (ΔQ) from the
In addition to the standard aeration volume (Q0), the optimum aeration volume (Q)
And the aeration air volume command value (A
Output as the analog value), and based on this, the ejector
It is also characterized by automatically controlling the air volume of the blower
Therefore, according to the method of the present invention, biological nitrification and denitrification treatment of human waste can be automatically performed.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a first embodiment.

FIG. 2 is an enlarged front view of a nitrification denitrification tank.

FIG. 3 is an enlarged front view showing another embodiment of the nitrification denitrification tank.

FIG. 4 is a graph showing a change in ORP when the amount of aeration air in the nitrification denitrification tank is appropriate.

FIG. 5 is a graph showing changes in ORP when the amount of aeration air is insufficient.

FIG. 6 is a graph showing changes in ORP when the amount of aeration air is excessive.

FIG. 7 is a flow sheet showing an example of an aeration air volume calculation process.

FIG. 8 is a flow sheet showing a second embodiment.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadahiko Hiramatsu 4-5-22 Doshumachi, Chuo-ku, Osaka City Yamada Industry Co., Ltd. (72) Koji Hasui 4-5-22 Doshomachi, Chuo-ku, Osaka No. Yamada Industry Co., Ltd. (56) Reference JP-A-6-238294 (JP, A) JP-A-9-108689 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/34 101 C02F 3/12

Claims (2)

(57) [Claims] 1. A allowed to flow into sewage human waste such as single nitrification denitrification tank, alternating rows that have a denitrification process by stirring the nitrification process by aeration, with nitrification process and de窒行in a batch by the time ratio constant, a biological nitrification denitrification treatment method for flowing sewage in degree de窒行, nitrification denitrification smell
ORP (oxidation-reduction potential) value measured every predetermined time
5 minutes before the nitrification process begins by detecting the ORP inflection point
If the ORP inflection point appears in the
Then, the nitrification process begins without the ORP inflection point appearing.
The aeration volume is decreased, and the nitrification process is
An ORP inflection point appeared between 5 minutes before and just before
And wherein to Rukoto it does not change the aeration amount in the case that, biological nitrification denitrification treatment methods night soil, and the like. 2. Nitrification with an ORP meter to increase or decrease the amount of aeration air
The ORP value is measured every predetermined time in the denitrification tank.
A / D output of ORP value (analog value such as voltage and current)
A / D conversion is performed by the converter, and the digital value (P) is changed.
The amount of change (ΔP) is calculated, and the amount of change (ΔP) and the denitrification process
Enter the elapsed time (t) after the start and start the nitrification process 5
When the ORP inflection point appears between minutes before and immediately before
Does not change the aeration volume, but 5 minutes before the nitrification process begins.
If the ORP inflection point appears in, or if the ORP inflection point
If the nitrification process has begun without appearing,
RP inflection point appears Elapsed time after denitrification process starts
Corresponding to (t), increase / decrease value by aeration air volume increase / decrease value calculator
(ΔQ) is calculated, and the increase / decrease value (ΔQ) is used as the standard aeration wind.
In addition to the volume (Q0), the optimum aeration air volume (Q)
Aeration air volume command value (analog value) via D / A converter
As the output of the ejector or blower based on this
A biological nitrification and denitrification treatment method for human waste, which is characterized by automatically controlling the air volume .