JP4564204B2 - Wastewater treatment method for wastewater treatment equipment - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a wastewater treatment apparatus for treating industrial wastewater, and more particularly to a wastewater treatment method for efficiently removing organic substances and nitrogen compounds.
[0002]
[Prior art]
A conventional wastewater treatment method for a wastewater treatment apparatus containing wastewater containing organic substances and nitrogen compounds will be described with reference to FIG. A wastewater treatment device 1 for industrial wastewater 13 includes a wastewater storage tank 8 to which a water supply device 9 is attached, a treatment water tank 2 to which a stirring device 3 is attached, an aeration device 4 and a drainage device 6 connected to the treatment water tank 2. The surplus sludge discharge device 10 connected to the treated water tank 2 and the control device 5 are included.
[0003]
The waste water 13 stored in the waste water storage tank 8 is sent to the treated water tank 2 by the water supply device 9. In the treated water tank 2, the waste water 13 is aerated by the aeration device 4, and at the same time, the waste water 13 is agitated by the agitation device 3. Remove.
[0004]
Some agitators 3 have an aeration function, such as an underwater agitation pump, that performs intake and aeration of air by rotation of an impeller. After stirring and aeration for a predetermined time, the stirring device 3 and the aeration device 4 are stopped and allowed to stand to precipitate activated sludge, and the treated water 11 and sludge are separated. The treated water 11 in the treated water tank 2 is discharged from the treated water tank 2 by the discharge device 6. Excess sludge 12, which is a surplus of activated sludge grown in the treated water tank 2, is discharged from the treated water tank 2 by the surplus sludge discharging device 10.
[0005]
Unlike industrial sewage, industrial wastewater is treated not by a continuous system but by rotation, and the amount of wastewater is very large and fluctuates over time. Therefore, the wastewater treatment apparatus 1 uses a wastewater storage tank 8 to absorb fluctuations in the amount of wastewater. have.
[0006]
The control device 5 controls the water supply device 9, the drainage device 6, the stirring device 3, the excess sludge discharge device 10, and the aeration device 4 so that a predetermined amount of waste water 13 is appropriately purified. The water feeding device 9 and the drainage device 6 have a structure using the natural flow of water by opening or closing a pump or an electric valve. A submersible agitation pump is used as the agitator 3, and a combination of a compressor and an aeration device is used as the aeration device 4. The agitator 3 and the aeration device 4 are submerged in a specification that performs aeration by rotating the pump. A pump may be used.
[0007]
In addition to the components shown in FIG. 2, the actual wastewater treatment apparatus 1 has advanced water treatment mechanisms such as a screen filter dust removal device, a sand removal device, a scum removal device, an ozone treatment device, a membrane treatment device, and a coagulation sedimentation device. Although it may accompany, there is no direct connection with the present invention, so the description is omitted.
[0008]
In recent years, removal of not only organic substances contained in wastewater but also nitrogen compounds has become an important issue. In the wastewater treatment apparatus 1 having the above-described configuration, nitrogen compounds are removed using activated sludge using a nitrification reaction and a denitrification reaction. In general, nitrogen compounds contained in wastewater are classified into organic nitrogen, ammoniacal nitrogen (NH ₄ -N), nitrate nitrogen (NO ₃ -N), and nitrite nitrogen (NO ₂ -N). Sexual nitrogen is mainly composed of proteins. When this protein is degraded by microorganisms, ammoniacal nitrogen (NH ₄ —N) is produced.
[0009]
The nitrification reaction is an oxidation reaction of ammoniacal nitrogen (NH ₄ -N) by nitrifying bacteria. As oxygen is consumed, the PH value in the wastewater decreases.
[0010]
By the way, in order to efficiently cause the nitrification reaction, it is necessary to grow nitrifying bacteria in the activated sludge.
[0011]
Since the growth rate of nitrifying bacteria is slower than that of other microorganisms, it is necessary to increase the residence time (SRT) in the activated sludge of nitrifying bacteria. The growth rate of nitrifying bacteria is greatly influenced by the waste water temperature and the DO (dissolved oxygen amount) value. The lower the both values, the slower the growth rate.
[0012]
In the denitrification reaction, when the DO value in the wastewater becomes low, the denitrifying bacteria in the activated sludge are bound oxygen contained in nitrate nitrogen (NO ₃ -N) and nitrite nitrogen (NO ₂ -N). Is a reaction for decomposing organic matter, that is, a reduction reaction of nitrate nitrogen (NO ₃ -N) and nitrite nitrogen (NO ₂ -N) using organic matter by denitrifying bacteria. Nitrogen denitrified from nitrate nitrogen (NO ₃ —N) and nitrite nitrogen (NO ₂ —N) is released into the atmosphere as nitrogen gas. Therefore, the denitrification reaction requires a low DO value and the presence of organic substances to be oxidized.
[0013]
As described above, by causing the nitrification reaction and the denitrification reaction at the same time, organic substances and nitrogen compounds in the wastewater are effectively removed.
[0014]
As described above, in the nitrification reaction, the oxygen amount, SRT, waste water temperature, and DO value in wastewater are closely related, and in the denitrification reaction, the DO value of wastewater and the content of organic matter are closely related. Of these, oxygen is supplied as aeration to the wastewater in the treated water tank by the aeration apparatus, and the DO value is adjusted by the aeration amount and the aeration time. SRT is adjusted by the amount of surplus sludge extracted by the surplus sludge discharger. The content of organic matter in the wastewater can be measured as a BOD (Biological Oxygen Demand) value and is present in the wastewater but is oxidized by aeration, and its amount decreases in a relatively short time.
[0015]
[Problems to be solved by the invention]
Thus, the adjustment of the amount of aeration by the aeration apparatus is important not only for removing organic substances but also for removing nitrogen. And the DO value and ORP (oxidation reduction potential) value in a processing water tank are used as a measured value for adjusting this aeration amount, and it measures with a DO meter and an ORP meter, respectively. However, the relationship between the amount of aeration by the aeration device and the content of organic substances and nitrogen compounds in the wastewater is only qualitatively understood, and the above relationship is taken quantitatively, and the aeration device is based on the quantitative results. The current situation is that there is no need to adjust the amount of aeration.
[0016]
The present invention has been made in consideration of such points, and clarifies the relationship between the aeration amount by the aeration apparatus and the contents of organic matter and nitrogen compounds in the wastewater, and adjusts the aeration amount and the aeration time. An object of the present invention is to provide a wastewater treatment method for a wastewater treatment apparatus that can efficiently remove organic substances and nitrogen compounds contained in wastewater.
[0017]
[Means for Solving the Problems]
The present invention relates to a wastewater treatment method using a wastewater treatment apparatus that removes organic matter and nitrogen compounds in treated wastewater by activated sludge, and agitating and aeration steps in which the wastewater in the treatment water tank is aerated by an aeration apparatus and stirred at the same time. Stopping the equipment, precipitating the activated sludge contained in the wastewater in the treated water tank, separating the wastewater into treated water and activated sludge, and a discharging process for discharging the treated water by the discharge device, and stirring In the aeration process, the aeration apparatus is controlled by the control device so that the nitrification reaction and the denitrification reaction occur simultaneously in the wastewater in the treatment water tank, and the aeration amount and the aeration time supplied to the treatment water tank are adjusted. This is a wastewater treatment method for a wastewater treatment apparatus.
[0018]
ADVANTAGE OF THE INVENTION According to this invention, the relationship between the aeration amount by an aeration apparatus and the content of the organic substance and nitrogen compound in wastewater is clarified, and the organic substance and nitrogen compound contained in wastewater can be removed efficiently.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a diagram showing an embodiment of a wastewater treatment method for a discharge device according to the present invention.
[0021]
As shown in FIG. 1, a wastewater treatment apparatus 1 includes a treatment water tank 2 for treating waste water containing organic substances and nitrogen compounds, a stirring device 3 installed in the treatment water tank 2 and stirring waste water in the treatment water tank 2, and a treatment Aeration device 4 for aeration in water tank 2, drainage device 6 for discharging waste water treated in treatment water tank 2 from treatment water tank 2, and aeration amount and aeration supplied to treatment water tank 2 by controlling aeration device 4 And a control device 5 for adjusting the time.
[0022]
The treated water tank 2 of the waste water treatment apparatus 1 includes a water temperature meter 7 a that measures the temperature of the waste water in the treated water tank 2, a PH meter 7 b that measures the PH value of the waste water in the treated water tank 2, and the waste water in the treated water tank 2. An ORP meter 7c that measures the ORP value and a DO meter 7d that measures the DO value of the wastewater in the treatment water tank 2 are provided. Each measured value is sent to the recorder 7e and continuously recorded by the recorder 7e. Is possible.
[0023]
As shown in FIG. 1, a water supply device 9 is installed in the wastewater storage tank 8, and an excess sludge discharge device (excess sludge pump) 10 that extracts excess sludge is connected to the treated water tank 2.
[0024]
In FIG. 1, the control device 5 controls not only the aeration device 4 but also the water supply device 9, the stirring device 3, the discharge device 6, and the excess sludge discharge device 10.
[0025]
Further, the water supply device 9 and the drainage device 6 have a structure that utilizes the natural flow of water by opening and closing of a pump or an electric valve. A submersible agitation pump is used as the agitator 3, and a combination of a compressor and an aeration device is used as the aeration device 4. The agitator 3 and the aeration device 4 are submerged in a specification that performs aeration by rotating the pump. A pump may be used.
[0026]
Next, the operation of the embodiment having such a configuration, that is, a wastewater treatment method will be described.
[0027]
First, as shown in FIG. 3, waste water (raw water) is supplied from the waste water storage tank 8 to the treated water tank 2 by the water feeding device 9 (raw water supply process E).
[0028]
Next, the wastewater in the treated water tank 2 is aerated by the aeration device 4 and at the same time, the wastewater is stirred by the stirring device 3 (stirring aeration step A). Thereafter, the aeration device 4 and the stirring device 3 are stopped, the activated sludge contained in the waste water in the treated water tank 2 is precipitated, and the waste water is separated into treated water and activated sludge (precipitation step B). Thereafter, the treated water in the treated water tank 2 is discharged by the drainage device 6 (discharge process C). Next, the raw water supply process E is repeated. FIG. 3 shows one cycle G, and the horizontal axis indicates the elapsed time (h) of each process.
[0029]
In the wastewater treatment method described above, the water supply device 9, the stirring device 3, the aeration device 4, and the discharge device 6 are each driven and controlled by the control device 5.
[0030]
Next, the wastewater treatment method by the control device 5 will be described in further detail. The control device 5 performs wastewater treatment control as follows based on the results of a wastewater treatment experiment performed in advance.
[0031]
First, in order to derive the relationship between the amount of aeration by the aeration device 4 and the contents of organic matter and nitrogen compounds in the wastewater in the treatment water tank 2 using the wastewater treatment device 1, a wastewater treatment experiment was performed with the settings described below. went.
[0032]
The wastewater treatment experiment was conducted under the following initial setting conditions: 1) Aeration amount 28 L / min, DO maximum value 2 to 4 mg / L, 2) Aeration amount 35 L / min, DO maximum value 4 to 6 mg / L, 3) Aeration amount 40 L / Min, with a maximum value of DO of 6 mg / L or more, continuous operation was performed for 2 weeks by batch processing for 12 hours per cycle, and water quality analysis was performed for the last one cycle operation. In the above water quality analysis, waste water is collected from the treated water tank 2 every hour from 10 minutes after the start of aeration, and ammonia nitrogen (NH ₄ -N), nitrite nitrogen (NO ₂ -N) in the waste water, The content of nitrate nitrogen (NO ₃ —N) was analyzed. Moreover, the reason why the maximum DO value is given a range as the initial setting condition is that there is a slight variation in the quality of the wastewater over time. Fig. 4 shows the quality of wastewater at the beginning of the experiment.
[0033]
In addition, in the water quality analysis, in the precipitation process B and the drainage process C, the activated sludge was separately collected and analyzed for the precipitated sludge and the supernatant obtained by sedimentation in the wastewater. A water sampler was used to collect the precipitated sludge. In the analysis of the precipitated sludge, centrifugation and filtration were performed as pretreatment. In addition to the waste water in the treated water tank 2, the treated water discharged from the treated water tank 2 is also BOD, SS, ammonia nitrogen (NH ₄ -N), nitrite nitrogen (NO ₂ -N) in the treated water. ) And nitrate nitrogen (NO ₃ —N) content were analyzed.
[0034]
Next, the initial setting conditions 1), 2) and 3) of the wastewater treatment experiment will be described with reference to FIGS.
[0035]
5 to 7 show that the initial setting conditions are 1) aeration amount 28 L / min, maximum DO value 2 to 4 mg / L (FIG. 5), 2) aeration amount 35 L / min, maximum DO value In the case of 4 to 6 mg / L (FIG. 6), 3) 40 L / min, the case where the maximum DO value is 6 mg / L or more (FIG. 7) is shown. In each of FIGS. 5 to 7, the horizontal axis represents elapsed time (h), and the vertical axis represents PH value or ammonia nitrogen (NH ₄ -N) and nitrite nitrogen (NO ₂ − in wastewater). N) content (mg / L) is shown. In each of FIGS. 5 to 7, (b) shows the elapsed time (h) on the horizontal axis, the ORP value (mV) on the vertical axis, or ammoniacal nitrogen (NH ₄ -N) and nitrite nitrogen (NO) in the wastewater. _2- N) content (mg / L). In each of FIGS. 5 to 7, (c) shows elapsed time (h) on the horizontal axis, DO value (mg / L) on the vertical axis, or ammoniacal nitrogen (NH ₄ -N) and nitrite nitrogen in the wastewater. indicating the content of the _{(NO 2 -N) (mg /} L).
[0036]
5 to 7, the solid line (1) is the result of water quality analysis on the supernatant, and shows the content (mg / L) of ammoniacal nitrogen (NH ₄ -N) in wastewater per unit volume. Yes. 5 to 7, the solid line (2) is the result of water quality analysis of the supernatant, and the content (mg / L) of nitrite nitrogen (NO ₂ -N) in the wastewater per unit volume is shown. Show. Dashed line (3) in addition 5 to 7 for precipitation sludge, shows the content of ammonia nitrogen (NH ₄ -N) per unit volume (mg / L). Dashed line (4) also in FIGS. 5-7 for the settled sludge, shows the content of nitrite nitrogen _(NO 2 -N) per unit volume (mg / L).
[0037]
The solid line (5) in FIG. 5 indicates the PH value, the solid line (5) in FIG. 6 indicates the ORP value, and the solid line (5) in FIG. 7 indicates the DO value. Further, each of (d) in FIG. 5 to FIG. 7 shows the result of water quality analysis in the last one-cycle operation of the wastewater treatment apparatus continuously operated for 2 weeks under each initial setting condition.
[0038]
Next, the wastewater treatment experiment results common to FIGS. 5 to 7 will be described.
[0039]
Immediately after the start of the stirring and aeration process, the PH value, ORP value, and DO value of each figure (a), (b), and (c) are unstable due to the influence of the wastewater injected into the treated water tank, but the aeration time As an initial tendency, the PH value decreases with the passage of time, the ORP value increases in a negative region, and the DO value takes a constant value of 0. Further, when the ORP value changes from a negative value to a positive value after a certain time has elapsed, the decrease rate of the PH value decreases, and then the PH value starts to increase. At the same time, the DO value starts to increase from the constant value 0.
[0040]
In addition, the aeration amount by the aeration apparatus 4 is set to be large in the order of FIG. 5, FIG. 6, and FIG. 7, but the time until the ORP value changes from a negative value to a positive value becomes shorter as the aeration amount increases. It has become. In addition, although the continuous analysis of the BOD value of the wastewater in the treated water tank 2 was not performed, in the stirring aeration process A, the BOD value of the wastewater in the treated water tank 2 immediately after the wastewater was charged was about 370 mg (the BOD value of the introduced wastewater) Is estimated to be reduced to the BOD value of the treated water quality shown in FIG. 5 to FIG. 7 (d) from 12,000 mg / L, wastewater input / cycle of 115L, and treated water tank volume of 3700L) Is done.
[0041]
In the precipitation process B and the drainage process C, the PH value gradually increases, the ORP value tends to decrease, and the DO value takes a constant value of 0 after a certain time has elapsed. In the precipitation step B, the nitrite nitrogen (NO ₂ -N) (FIGS. 5 to 7 (4)) in the precipitated sludge is reduced to 0 within 1 hour after the start of the precipitation step B. Ammonia nitrogen (NH ₄ —N) is not significantly changed in both the supernatant (FIGS. 5 to 7 (1)) and the precipitated sludge (FIGS. 5 to 7 (3)). As can be seen from FIGS. 5 to 7 (d), nitrate nitrogen (NO ₃ —N) was 0 mg / L in all experiments, so the notation in FIGS. 5 to 7 was omitted. ing.
[0042]
The reason why nitrate nitrogen (NO ₃ -N) is 0 mg / L in the water quality test of all experiments is as follows. That is, the nitrogen compound changes in the order of organic nitrogen, ammonia nitrogen (NH ₄ -N), nitrite nitrogen (NO ₂ -N), and nitrogen gas, and nitrate nitrogen is generated in the course of each change. This is because is not done.
[0043]
Next, the experimental results of FIGS. 5 to 7 will be described individually.
[0044]
FIGS. 8 to 10 show the individual experimental results of FIGS. 5 to 7, respectively, for one cycle G for each time period, DO value, BOD value, ammonia nitrogen (NH ₄ -N), nitrite nitrogen (NO ₂ − 11 is a chart summarizing features of N).
[0045]
In each of the above-mentioned time zones, the ORP value becomes approximately 0 from the start of the stirring / aeration process A until the start of the stirring / aeration process A (-0.5 to 0.0 h) from 30 minutes before the introduction of the wastewater in one cycle G. Until the time, the ORP value is divided into the period from the time when the ORP value becomes about 0 to the end of the stirring aeration process A and the time from the start of the precipitation process B to the end of the drainage process C (6.0 to 11.5 h). Yes.
[0046]
First, the case where the aeration amount is set to 28 L / min (FIG. 5) will be described.
[0047]
In the precipitation step B with an aeration amount of 28 L / min, the precipitation sludge was observed to float. Since the precipitation sludge floats as low as 28 L / min, the BOD value cannot be reduced in the stirring aeration process A. Therefore, in the precipitation process B, nitrite nitrogen (NO ₂ -N) is denitrified. It is thought that the precipitated sludge was floated by the generated nitrogen gas bubbles. Due to the sludge floating, the SS value of the treated water is increased as compared with the case where the aeration amount is set to 35 L / min (FIG. 6D) and 40 L / min (FIG. 7D).
[0048]
Waste water treatment experiment results BOD: 140 mg / L and SS: 180 mg / L (FIG. 5 (d)) with an aeration amount of 28 L / min are BOD: 120 mg / L and SS: 150 mg / L, which are the daily average values of Japanese emission standards. The value exceeds L (reference value).
[0049]
Next, the case where the aeration amount is set to 40 L / min (FIG. 7) and the aeration amount is set to 35 L / min (FIG. 6) will be compared.
[0050]
The BOD value at an aeration amount of 40 L / min is kept low compared to the BOD value at an aeration amount of 35 L / min. However, since the DO value is high on average, the denitrification reaction is difficult to proceed, and the nitrogen compound Exists in the state of nitrite nitrogen (NO ₂ -N), which is in the process of denitrification reaction, and the nitrite nitrogen (NO ₂ -N) concentration is high, so the progress of nitrification reaction is also suppressed Is done. Further, in the case of an aeration amount of 40 L / min, the ammoniacal nitrogen (NH ₄ —N) concentration is high compared with the aeration amounts of 28 L / min and 35 L / min, although the aeration amount is large.
[0051]
Although the BOD value (Fig. 6 (d)) at an aeration amount of 35 L / min is larger than that at an aeration amount of 40 L / min (Fig. 7 (d)), it is below Japan's emission standards and sludge floats. Not. Further, when the aeration amount is set to 35 L / min, since the DO value is lower than that at 40 L / min on average, the progress of the denitrification reaction is quick and the concentration of nitrite nitrogen (NO ₂ -N) is low. Therefore, the nitrification reaction proceeds quickly.
[0052]
Therefore, when the initial setting conditions 1), 2) and 3) are compared, 2) When the aeration amount is set to 35 L / min, the organic substances and nitrogen compounds contained in the wastewater can be removed most efficiently. Further, as is clear from FIG. 6 showing the experimental results when the aeration amount is set to 35 L / min, the sublimation is performed for about 30 minutes before the completion of the stirring aeration step A so that the nitrification reaction and the denitrification reaction proceed simultaneously. When the amount of aeration is adjusted so that the nitrate nitrogen concentration is increased to a range of about 0 to 10 mg / L, organic substances and nitrogen compounds contained in the wastewater can be removed most efficiently.
[0053]
FIG. 11 shows a modification of the wastewater treatment method of the wastewater treatment apparatus 1 according to the present invention.
[0054]
A nitrite nitrogen ion concentration meter 7f is installed in the treated water tank 2, and the control device 5 determines the amount of nitrite nitrogen (about 30 minutes before the end of the stirring and aeration step A based on the information from the nitrite ion concentration meter 7f. The aeration amount and the aeration time are adjusted so that the concentration of NO ₂ -N) increases to a range of about 0 to 10 mg / L.
[0055]
In FIG. 11, the nitrite nitrogen (NO ₂ —N) concentration is within a range of about 0 to 10 mg / L for about 30 minutes before the completion of the stirring and aeration step A so that the nitrification reaction and the denitrification reaction proceed simultaneously. By adjusting the amount of aeration so that it increases, the progress of the denitrification reaction is fast, and the nitrite nitrogen (NO ₂ -N) concentration is low, so the progress of the nitrification reaction is fast, and the nitrification reaction and denitrification reaction are used. Thus, organic substances and nitrogen compounds in wastewater can be efficiently removed.
[0056]
Second embodiment Figs. 12 and 13 are diagrams showing a second embodiment of the present invention. As shown in FIG. 12 and FIG. 13, a nitrification reaction and a denitrification reaction occur simultaneously in the wastewater in the treated water tank 2 between the agitating aeration process A and the precipitation process B to prevent the activated sludge from rising in the wastewater. Thus, only the stirring device 3 is operated by the control device 5 (stirring step D). 12 and 13, the same parts as those of the first embodiment shown in FIGS. 1 and 3 to 11 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0057]
From the experimental results of FIGS. 5 to 7, it is presumed that in each precipitation step B, denitrification of nitrite nitrogen (NO ₂ —N) proceeds using the organic matter in the activated sludge. Therefore, by providing the stirring step D (FIG. 12) that operates only the stirring device 3 between the stirring aeration step A and the precipitation step B, denitrification of nitrite nitrogen (NO ₂ -N) by stirring the activated sludge. The reaction can be promoted, and the precipitation sludge in the precipitation step B, which has become a problem when the aeration amount is set to 28 L / min (FIG. 5), can also be prevented.
[0058]
That is, in the stirring aeration process A, the amount of aeration from the aeration apparatus 4 is small, and the nitrite nitrogen (NO ₂ -N) concentration is increased to a range of 0 to 10 mg / L for about 30 minutes before the completion of the stirring aeration process A. In the case where it remains at 0 mg / L, the denitrification reaction can be further promoted and the precipitation sludge can be prevented from rising by providing the stirring step D after the completion of the stirring and aeration step A.
[0059]
FIG. 13 shows experimental results in which the stirring step D is provided between the stirring and aeration step A and the precipitation step B at a setting of an aeration amount of 28 L / min. In the stirring step D, the wastewater in the treated water tank 2 was stirred by a stirring device for about 1 hour.
[0060]
In the experimental result of FIG. 13, it can be seen that the provision of the stirring step D promotes the denitrification reaction and can prevent the precipitation sludge from floating. Furthermore, it was confirmed that not only the BOD value but also the SS value can be significantly reduced, as can be seen from the result of comparing FIG. 5 (d) and FIG. 13 (d).
[0061]
Thus, between the stirring aeration process A and the precipitation process B, by providing the stirring process D which stirs the wastewater in the treated water tank 2 by the stirring apparatus for about 1 hour, the inside of the treated water tank 2 is efficiently provided. It can be seen that the nitrification reaction and the denitrification reaction can occur simultaneously in the wastewater to remove organic substances and nitrogen compounds.
[0062]
【The invention's effect】
As described above, according to the present invention, in the wastewater treatment method for a wastewater treatment apparatus that removes organic matter and nitrogen compounds in wastewater with activated sludge, the amount of aeration by the aeration apparatus determined in advance and the organic matter and nitrogen compounds in the wastewater. By adjusting the aeration amount and aeration time of the aeration device so that the nitrification reaction and the denitrification reaction occur simultaneously based on the relationship between the nitrogen content and the nitrogen content, the nitrogen compounds and organic substances contained in the wastewater can be efficiently Can be removed.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a first embodiment of a wastewater treatment method for a discharge device according to the present invention. FIG. 2 is a diagram showing a conventional wastewater treatment device. FIG. 3 is a wastewater treatment method for a discharge device according to the present invention. FIG. 4 is a diagram showing the quality of wastewater at the start of the experiment. FIG. 5 is a diagram showing the experimental result of the aeration amount of 28 L / min. FIG. 6 is a diagram showing the experimental result of the aeration amount of 35 L / min. FIG. 7 is a diagram showing experimental results for an aeration amount of 40 L / min. FIG. 8 is a diagram showing characteristics of experimental results for an aeration amount of 28 L / min. FIG. 9 is a diagram showing features of experimental results for an aeration amount of 35 L / min. FIG. 10 is a chart showing the characteristics of the experimental results with an aeration rate of 40 L / min. FIG. 11 is a view showing a wastewater treatment apparatus equipped with a nitrite nitrogen ion concentration meter. FIG. 12 is a diagram of a second embodiment of the present invention. Fig. 13 shows each step of the waste water treatment method. Fig. 13 shows waste water treatment shown in Fig. 12. It shows the experimental results using the law [Description of symbols]
DESCRIPTION OF SYMBOLS 1 Wastewater treatment apparatus 2 Treated water tank 3 Stirring apparatus 4 Aeration apparatus 5 Control apparatus 6 Drainage apparatus 7a Water temperature meter 7b PH meter 7c ORP meter 7d DO meter 7e Record meter 7f Nitrite ion concentration meter 8 Wastewater storage tank 9 Water supply device 10 Excess sludge Discharge device A Stirring aeration process B Precipitation process C Drainage process D Stirring process E Raw water supply process

Claims (2)

In a wastewater treatment method using a wastewater treatment device that removes organic matter and nitrogen compounds in wastewater with activated sludge,
A step of supplying wastewater containing organic matter and a nitrogen compound and not containing nitrate nitrogen into the treated water tank;
An aeration process in which waste water in the treated water tank is aerated by an aeration apparatus and is agitated by an agitator at the same time;
A precipitation step of stopping the aeration device and the stirring device, precipitating the activated sludge contained in the wastewater in the treated water tank, and separating the wastewater into treated water and activated sludge;
A discharge step of discharging treated water by a discharge device,
In the wastewater supplied into the treated water tank, the concentration of nitrate nitrogen is maintained at 0 mg / L during each step of the wastewater treatment,
In the agitation aeration process, the nitrite nitrogen concentration continues to increase for 30 minutes before the agitation aeration process is completed by the control device in the wastewater in the treated water tank, and the nitrite nitrogen concentration is 10 mg / L at the end of the agitation aeration process. A wastewater treatment method for a wastewater treatment apparatus, wherein the aeration amount of the aeration apparatus is adjusted so as not to exceed, and thereby a nitrification reaction and a denitrification reaction occur simultaneously. In a wastewater treatment method using a wastewater treatment device that removes organic matter and nitrogen compounds in wastewater with activated sludge,
A step of supplying wastewater before treatment of wastewater containing organic matter and nitrogen compounds and not containing nitrate nitrogen into the treated water tank;
An aeration process in which waste water in the treated water tank is aerated by an aeration apparatus and is agitated by an agitator at the same time;
A stirring step of stopping the aeration apparatus and stirring the waste water in the treated water tank with a stirring device;
A precipitation step of stopping the agitator, precipitating the activated sludge contained in the wastewater in the treated water tank, and separating the wastewater into treated water and activated sludge;
A discharge step of discharging treated water by a discharge device,
In the wastewater supplied into the treated water tank, the concentration of nitrate nitrogen is maintained at 0 mg / L during each step of the wastewater treatment,
In the agitation process, the nitrite nitrogen concentration continues to increase for 30 minutes before the end of the agitation process in the wastewater in the treated water tank, and the nitrite nitrogen concentration does not exceed 10 mg / L at the end of the agitation process A wastewater treatment method for a wastewater treatment apparatus, wherein the stirring of the stirring apparatus is adjusted so that a nitrification reaction and a denitrification reaction occur simultaneously.

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