JP2002224696A - Method for treating organic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic waste treating method in which an excess of sludge can be prevented from being generated by restraining activated sludge from propagating, drawing-out and retreating of sludge are unnecessary and organic waste can be treated with extremely high efficiency. SOLUTION: This organic waste treating method in which sludge is not withdrawn to the outside is carried out by adding the organic waste from a raw water tank 4 to activated sludge water in an aeration tank 12 so that the concentration of propagating nitrifying bacteria is not lowered, adding a pH adjusting agent from a pH adjusting agent tank 10 to the activated sludge water in the tank 12 so that the pH of the activated sludge water in the tank 12 is kept to be >=5, supplying oxygen of the amount equal to or more than the oxygen requirement to biodegradation of organic carbon in the activated sludge water, endogenous respiration of a microbe, nitrification of ammonia nitrogen and auto-oxidation of the microbe to the activated sludge water from a Roots blower 20 through an air diffusing pipe 18 and discharging the activated sludge water to the outside of the tank 12 so that the concentration of propagating nitrifying bacteria is not lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating organic waste, and more particularly, to a method for biodegrading organic waste such as garbage, shochu waste, livestock manure, and excess activated sludge. About.

[0002]

2. Description of the Related Art In recent years, industries have rapidly developed, populations have been concentrated in cities, and lifestyles and agricultural forms have changed. As a result, wastes have been generated in large amounts and intensively.

[0003] When the amount of wastewater and waste generated from industry and daily life exceeds the purification ability of nature, various problems on human health and environmental preservation arise, and for that purpose, wastewater treatment and waste treatment are performed. It became so.

Among these, for example, in the wastewater treatment including organic waste such as garbage, shochu waste liquid, livestock manure, etc., biodegradation treatment by microorganisms is generally performed.

[0005] As a typical treatment method in which the above wastewater containing organic waste is treated by microorganisms, there is an activated sludge method.

In urban sewage treatment, rural settlement wastewater treatment, fishing village settlement wastewater treatment, etc., the BOD of raw water introduced into activated sludge water in an aeration tank at a treatment plant is approximately 200 p.
pm and the concentration of ammonia nitrogen are 50 ppm or less.

[0007] The amount of input raw water depends on the scale of settlements in rural settlement drainage treatment and fishing village settlement drainage treatment.
00m ³ / day, it will reach tens of thousands of m ³ / day in urban sewage.

As described above, the amount of organic waste to be treated for wastewater is enormous.

However, when the above-mentioned organic waste is treated using the conventional activated sludge method, 40 to 70% of the organic waste contained in the wastewater is converted into sludge. There is a problem that a large amount of excess sludge is generated as secondary waste.

[0010] The amount of excess sludge generated as secondary waste is
In recent years, the amount of excess sludge generated in Japan has reached tens of millions of tons per year. Various methods have been proposed to treat this excess sludge. For example, there are a long-time aeration method, an oxygen aeration method, a method of pretreatment with ozone, and the like.

The long-time aeration method and the oxygen aeration method are treatment methods for reducing the amount of sludge by the auto-oxidation of the sludge. The ozone pretreatment method is a method in which surplus sludge is sterilized with ozone, the surplus sludge is changed into a form that can be easily treated, and then treated by an activated sludge method. Other methods too. This is a method in which the excess sludge is sterilized by some physicochemical method, the excess sludge is changed into a form that can be easily treated, and then the activated sludge is treated.

However, these conventional methods for treating excess sludge require complicated facilities such as an oxygen supply facility and an ozone supply facility, require a long operation, and require enormous facility and operation costs. And has problems in equipment and operation.

Therefore, it is an urgent task to reduce or preferably eliminate the excess activated sludge which has reached a huge amount.

Further, in the treatment of organic waste with the above-mentioned activated sludge, there is a problem that the treatment of ammonia nitrogen is not completely performed.

[0015]

As a result of various studies to solve the above problems, the present inventors have found that activated sludge water nitrate nitrogen and nitrite nitrogen in the aeration tank are capable of treating excess sludge. Has not always been affected.

As a result of further studies, the present inventors added organic waste and a pH adjuster to the activated sludge water in the aeration tank, and introduced a sufficient amount of air bubbles into the activated sludge water. By maintaining the pH of the activated sludge water in the aeration tank at 5 or more, preferably at 7 or more, and keeping the concentration of nitrifying bacteria high, it is possible to treat ammonia nitrogen in organic waste and organic carbon at the same time. In addition, the present inventors have learned that the growth of excess activated sludge can be suppressed, and have completed the present invention.

Accordingly, it is an object of the present invention to provide a method for treating organic waste which has solved the above-mentioned problems.

[0018]

The present invention to achieve the above object is as described below.

[1] A method for treating organic waste by adding organic waste to activated sludge water in an aeration tank and introducing air bubbles into the activated sludge water. And a pH adjuster, and activates the activated sludge water to release more oxygen than is required for biodegradation of organic carbon in the activated sludge water, endogenous respiration of microorganisms, nitrification of ammonia nitrogen, and autooxidation of microorganisms. To maintain the pH of the activated sludge water in the aeration tank at 5 or more, simultaneously treat the carbon and nitrogen in the same tank, and add organic waste to the activated sludge water in the aeration tank and Discharge of activated sludge water outside the aeration tank is performed within a range that does not reduce the concentration of the growing nitrifying bacteria, thereby suppressing the growth of sludge and, as a result, a method of treating organic waste that does not take sludge outside. .

[2] Adjust the pH of the activated sludge water in the aeration tank to 7
The method for treating organic waste according to [1], which is maintained as described above.

[3] The method for treating organic waste according to [1], wherein the organic waste is excess sludge.

[4] The method for treating organic waste according to [1], wherein the organic waste is garbage or livestock manure.

[5] The addition of organic waste to the activated sludge water in the aeration tank and the discharge of the activated sludge water out of the aeration tank when necessary are performed in a batch mode, and the number of nitrifying bacteria at the end of the previous batch is determined. The method for treating organic waste according to [1], wherein the organic waste is added to the activated sludge water in the aeration tank and the activated sludge water is discharged out of the aeration tank while maintaining the number of nitrifying bacteria or more.

[6] The treatment of organic waste according to [5], wherein the amount of activated sludge discharged to the outside of the aeration tank in each batch is 1/7 or less of the total amount of activated sludge in the aeration tank. Method.

[0025]

The operation of the method for treating organic waste according to the present invention is considered as follows.

In the activated sludge water in the aeration tank, the treatment of organic carbon is also performed simultaneously in the same tank under aerobic conditions for treating ammonia nitrogen. At the same time, the amount of oxygen necessary for the auto-oxidation of microorganisms is supplied while treating ammonia nitrogen and organic carbon.

As described above, the method of the present invention suppresses the growth of activated sludge and eliminates the excess sludge taken out to the outside by performing the treatment for securing the amount of oxygen necessary for the autooxidation of microorganisms.

On the other hand, in the conventional method, since activated sludge multiplies, it is necessary to take out excess sludge generated in large quantities to the outside.

Therefore, in the method of the present invention, it is necessary to ensure the amount of oxygen necessary for the auto-oxidation of the microorganism as compared with the conventional method. On the other hand, since no excess sludge is generated, it is not necessary to take out the excess sludge and aggregate it.

Hereinafter, the present invention will be described in detail.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradation treatment of organic waste is performed, for example, according to the flow shown in FIG. Hereinafter, the method for treating organic waste according to the present invention will be described along these flows.

The organic waste to be treated in the present invention includes, for example, excess sludge generated in wastewater treatment facilities such as urban sewage, rural village wastewater, and fishing village wastewater.
Food factory and brewing industry waste such as shochu waste liquid, livestock manure,
Garbage discharged from home kitchens and restaurant kitchens,
The present invention can be applied to food waste discharged from supermarkets, plants and the like discharged by lawn mowing or planting.

In the organic waste treatment flow shown in FIG. 1, excess sludge generated in the wastewater treatment equipment (activated sludge method) 2 is treated as organic waste.

Excess sludge (organic waste) generated by treating the raw water stored in the raw water tank 4 is supplied to the adjusting tank 6. Into the adjusting tank 6, sediment sludge separated and settled in the sedimentation tank 8 is returned, and a pH adjusting agent tank 10 is set.
Is charged with a pH adjuster.

In the conditioning tank 6, air sent from the roots blower 16 to the activated sludge water containing organic waste in the conditioning tank 6 from the air diffuser 14 at the bottom of the conditioning tank 6 for aerobic pretreatment. Is introduced as air bubbles to perform aeration.

Organic waste and a pH adjuster are charged in the adjusting tank 6, and the activated sludge water subjected to aeration is transferred to the aeration tank 12. As a method of putting the organic waste in the adjusting tank 6 into the aeration tank 12, a batch method is more preferable from the viewpoint of nitrogen treatment.

The method of charging the organic waste and the pH adjuster into the aeration tank 12 may be performed through the adjustment tank 6 as described above.
2 may be directly charged.

In the aeration tank 12, air from the roots blower 20 is introduced as air bubbles from the air diffuser 18 at the bottom of the aeration tank 12, and the activated sludge water sent from the adjustment tank 6 is aerated and, if necessary, turned off. Aeration tank 1 from foam showering 22
It is preferable to spray activated sludge water of No. 2.

The total organic carbon concentration in the activated sludge water in the aeration tank 12 is preferably 2000 ppm or more.
~ 200000 ppm is more preferred.

The pH of the activated sludge water in the aeration tank 12 is preferably 5 or more, more preferably 7 to 9, and particularly preferably 7 to 8.

When the organic waste is charged into the aeration tank 12 via the adjusting tank 6 in a batch system, the activated sludge water immediately after the organic waste is charged into the aeration tank 12 in each batch. The pH is preferably 7 to 9, and the pH of the activated sludge water after aeration treatment in each batch is preferably 5 or more.

In order to maintain the pH of the activated sludge water in the aeration tank 12 within the above range, the pH may be adjusted by directly adding the pH adjuster from the pH adjuster tank 10 to the aeration tank 12. It is easy to maintain the pH of the activated sludge water in the aeration tank 12 in the above range by adjusting the pH in the adjustment tank 6. For this purpose, it is preferable to measure the pH of the activated sludge water in the aeration tank 12 and feed the value back to the pH adjustment in the adjustment tank 6.

Further, the pH of the activated sludge water in the aeration tank 12 is adjusted to the above range by taking the pH of the activated sludge water in the aeration tank 12 into a computer and feeding it back to the amount of the pH adjuster added to the activated sludge water. Maintaining is also preferred.

It is necessary to sufficiently aerate the activated sludge water.
The supply of oxygen to activated sludge water by aeration exceeds the amount of oxygen required for biodegradation of organic carbon in activated sludge water, endogenous respiration of microorganisms, nitrification of ammonia nitrogen, and autooxidation of microorganisms There is a need.

The required amount of oxygen can be calculated by empirical values and stoichiometric calculations. Generally, it is easy to maintain the amount of dissolved oxygen in the activated sludge water at a value of 3 mg / L or more, preferably 5 mg / L or more, at least from 5 hours before the input of the organic waste to the input. Can be achieved.

If the oxygen supply is insufficient, the oxidation of ammonia nitrogen to nitrate nitrogen is inhibited, and
An increase in sludge occurs. When the oxygen supply exceeds the above amount sufficiently, the ammonia nitrogen is changed to nitrate nitrogen, and the sludge is surely reduced.

In the present invention, the amount of nitrifying bacteria in the activated sludge water in the aeration tank 12 needs to be sufficiently high. In order to maintain the concentration of the nitrifying bacteria growing in the aeration tank 12, the amount of activated sludge water discharged to the outside of the aeration tank caused by the addition of the activated sludge water containing organic waste to be introduced into the aeration tank 12 is controlled. That is, in the case of batch processing, it is necessary to end the next batch processing while keeping the number of nitrifying bacteria equal to or greater than the number of nitrifying bacteria in the activated sludge water at the end of the previous batch processing.

When the number of nitrifying bacteria is repeatedly reduced at the end of the next batch process as compared with the end of the previous batch process,
The number of nitrifying bacteria decreases. As a result, the ammonia nitrogen remains in the activated sludge water without being nitrified, and the organic waste and the sludge in the activated sludge water are not sufficiently reduced, and the excess sludge increases.

In the case where the system for charging the organic waste into the aeration tank 12 via the adjustment tank 6 is a batch system, the aeration tank 1
When the organic waste is put into the aeration tank 2, the organic waste in the aeration tank 12 is subjected to biodegradation treatment to reduce the weight thereof.
Activated sludge water below the input amount is discharged to the outside.

The activated sludge discharged out of the aeration tank 12 is
It is transferred to the sedimentation tank 8 and settled and separated into a supernatant liquid and sedimentation sludge (excess sludge).

The supernatant is discharged out of the system as treated water. On the other hand, the settled sludge is returned to the adjustment tank 6,
In the next batch of excess sludge (raw water).

According to the method for treating organic waste of the present invention, the growth of activated sludge is suppressed, and the amount of precipitated sludge generated is small. Therefore, the whole amount of the settled sludge is
It can be returned as activated sludge water for input, and there is usually no need to withdraw and reprocess a part of the settled sludge.

In the case of batch treatment, the amount of activated sludge water that can be discharged out of the aeration tank 12 in each batch without reducing nitrifying bacteria is preferably 1/7 or less of the total amount of activated sludge water in the aeration tank 12. . In order to treat ammonia nitrogen by not adding the organic waste to the activated sludge water in the aeration tank and discharging the activated sludge water out of the aeration tank beyond the growth rate of nitrifying bacteria as described above. A sufficient amount of nitrifying bacteria can be maintained in the aeration tank 12.

In the above description, the case where excess sludge is treated as organic waste has been described. However, the present invention is not limited to this, and in the case of garbage, livestock manure, etc., the same applies to the case of using excess sludge instead of or together with excess sludge. Can be processed.

When the organic waste is the above-mentioned garbage, it is preferable to perform pretreatment such as pulverization using a crusher such as a disposer or a fine crusher (mill).

[0056]

EXAMPLES Hereinafter, the present invention will be described specifically and in detail with reference to examples, but the present invention is not limited to the examples.

Each physical property value was measured by the following method.

Total organic carbon concentration (TOC): Measured using TOC-5000 manufactured by Shimadzu Corporation.

Dissolved oxygen content (DO): Measured using KDS-25 manufactured by Daisek Corporation.

PH: Measured using GRT-1 manufactured by Daisek Corporation.

Ammonia nitrogen concentration (NH ₄ -N):
(ATI) The measurement was performed using a composite electrode type 9307BN manufactured by Orion.

Nitrate nitrogen concentration (NO ₃ -N): (AT
I) Measurement was performed using a membrane electrode 95-12BN manufactured by Orion.

Examples 1 and 2 and Comparative Examples 1 and 2 Using the treatment flow of organic waste shown in FIG. 1, the waste was generated in waste water treatment equipment (activated sludge method) 2 and stored in raw water tank 4. Regarding the excess sludge (organic waste), the treatment period of 188 days was changed to the first period of 0 to 70 days (Example 1), 71 to 71 days.
It is divided into four periods of a 2-1 period of 116 days (Comparative Example 1), a 2-2 period of 117 to 147 days (Comparative Example 2), and a third period of 148 to 188 days (Example 2), Organic waste (raw water) was treated under different treatment conditions in each period.

In the treatment of the raw water, the activated organic sludge, which is excess sludge being treated in the aeration tank 12, is subjected to a predetermined treatment every day, and the total organic carbon concentration, pH, ammonia nitrogen concentration, and nitrate nitrogen concentration are changed. It was measured.

FIGS. 2 to 6 show the results of measurement of the activated sludge water in the aeration tank 12 and the cumulative carbon amount (cumulative input carbon amount) of the input excess sludge, with the number of treatment days as a horizontal axis. It is a graph shown.

As individual graphs, FIG. 2 is a graph showing the transition of the cumulative input carbon amount and the total organic carbon amount of the activated sludge water in the aeration tank 12 (carbon amount in the aeration tank). FIG. 3 shows the amount of carbon in the aeration tank and the pH of the activated sludge water in the aeration tank 12.
It is a graph which shows transition of (pH in an aeration tank). FIG.
Amount of carbon in aeration tank and ammonia nitrogen concentration of activated sludge water in aeration tank 12 (ammonia nitrogen concentration in aeration tank)
5 is a graph showing the transition of. FIG. 5 is a graph showing changes in the concentration of ammonia nitrogen in the aeration tank and the concentration of nitrate in activated sludge water in the aeration tank 12 (the concentration of nitrate nitrogen in the aeration tank). FIG. 6 is a graph showing changes in the ammonia nitrogen concentration in the aeration tank and the pH in the aeration tank.

Example 1 (Phase 1) Raw water tank 4 generated in wastewater treatment facility (activated sludge method) 2
4 m ³ of excess sludge (raw water) stored in the aeration tank 12, a pH adjuster is added, air bubbles are introduced, and p
H was adjusted to 6.5 and activated sludge water having an ammonia nitrogen concentration of 5 mg / L or less. Thereafter, the surplus sludge (raw water) was charged into the aeration tank 12 through the adjustment tank 6 in a batch manner every predetermined number of treatment days as described below.

In each batch, 0.03 m ³ of raw water was charged into the adjusting tank 6. Raw water 0.0
The value obtained by accumulating the total amount of organic carbon in ³ m ³ for each batch is shown in FIG. 2 as the accumulated input carbon amount.

To the raw water in the adjusting tank 6, the sludge returned from the sedimentation tank 8 described later is put, and the pH adjusting agent tank 1
From 0, a predetermined amount of the pH adjuster was added. In the first stage of the treatment period, the amount of the pH adjuster added was adjusted so that the pH of the activated sludge water in the aeration tank 12 did not become 5 or less as shown in FIGS.

In order to perform aerobic pretreatment in the adjusting tank 6, air from the roots blower 16 was introduced as air bubbles from the air diffuser 14 at the bottom of the adjusting tank 6, and aeration was performed. Excess sludge (raw water) in the adjusting tank 6 after the aeration treatment was transferred to the aeration tank 12 and merged with the activated sludge water in the aeration tank 12.

In the aeration tank 12, the air of the roots blower 20 is introduced as air bubbles from the air diffuser 18 at the bottom of the aeration tank 12 to perform aeration, and if necessary, from the defoaming showering 22 to the inside of the aeration tank 12. Activated sludge was sprayed.

The amount of aeration is 0.5 m ³ / min. From the measurement of dissolved oxygen, this aeration is sufficient for biodegradation of organic carbon, endogenous respiration of microorganisms, auto-oxidation of microorganisms, and nitrification of ammonia nitrogen. Supply was assured.

In each batch, regarding the activated sludge water after the aeration treatment in the aeration tank 12, the amount of activated sludge water in the aeration tank 12 before transfer of the excess sludge from the adjustment tank 6 to the aeration tank 12 was 4 m ³ . The increased amount is transferred to the sedimentation tank 8
And settled and separated into a supernatant and a settled sludge.

The supernatant was discharged out of the system as treated water, and the settled sludge was returned to the adjusting tank 6.

In the first stage of the processing period, the above batch operation was repeated for a period of 0 to 70 days. The results are shown in FIGS.

Comparative Example 1 (Phase 2-1) The feed amount of raw water to the adjusting tank 6 in each batch was 0.06
０．１0.1 m ^3, and the introduction of the pH adjuster to the raw water in the adjusting tank 6 was stopped. As a result, as shown in FIGS. 3 and 6, the pH of the activated sludge water in the aeration tank 12 was 5 to 4.2. , And the same batch operation as in Example 1 (first phase) was performed except that this batch operation was repeated for a period of 71 to 116 days. The results are shown in FIGS.

Comparative Example 2 (Phase 2-2) The amount of raw water charged to the adjusting tank 6 in each batch was 0.03
and m ^3, following the operation of Comparative Example 1 (2-1 phase),
Stop supplying the pH adjusting agent to the raw water in the adjusting tank 6,
As a result, as shown in FIGS. 3 and 6, the pH of the activated sludge in the aeration tank 12 changed from 4.2 to 3.8, and this batch operation was repeated for a period of 117 to 147 days. The same batch operation as in Example 1 (first phase) was performed. The results are shown in FIGS.

Example 2 (Third Phase) Following the operation of Comparative Example 1 (2-2nd phase), the input amount of raw water to the adjusting tank 6 in each batch was set to 0.03 m ³ ,
On the other hand, the supply of the pH adjuster to the raw water in the adjusting tank 6 was restarted. Next, as shown in FIGS. 3 and 6, the pH of the activated sludge water in the aeration tank 12, which was reduced to 3.8 in the second to second stages of the treatment period, was increased, and a pH adjuster was added so that the pH became 7 or more. The amount was adjusted, and the same batch operation as in Example 1 (the first phase) was performed.
Repeated for a period of ~ 188 days. The results are shown in FIGS.

[0079]

[Table 1]

In Table 1, the input carbon amount indicates the accumulated total organic carbon amount of the input excess sludge in each treatment period.

The increase in the amount of carbon in the aeration tank (kg) indicates the amount of increase in the amount of carbon in the aeration tank during each treatment period.

The sludge treatment rate (unit: mass%) in each treatment period is [1- (increase in the amount of carbon in the aeration tank in each treatment period / accumulated carbon amount in each treatment period)] × 1
The numerical value obtained by the formula of 00 is shown.

The NH ₄ —N concentration is the ammonia nitrogen concentration of the activated sludge in the aeration tank 12 (the ammonia nitrogen concentration in the aeration tank), and is N times in the processing period for which the NH ₄ —N concentration is to be determined. If the batch operation of
Shows the average of the times.

The NH ₄ -N treatment rate (unit: mass%)
When performing the N times of batch operation in the processing period of the target seeking H ₄ -N treatment rate, indicating the value of the ammonia nitrogen treatment ratio obtained by the following equation.

[0085]

(Equation 1)

As shown in FIG. 2 and Table 1, the total amount of organic carbon (the amount of aerated water) in the activated sludge water in the aeration tank 12 despite the introduction of excess sludge for the first 70 days (first period) It can be seen that the amount of carbon in the tank did not change (straight line 1). Thus, the sludge treatment rate in the first treatment period was 100% by mass.

The following 76 days (and) (phase 2-1: 71)
The changes in the amount of carbon in the aeration tank during the period from the 116th day to the 116th and the 2-2nd period from the 117th to the 147th day are straight lines rising to the right as shown by the straight line 2, and the sludge treatment rate is 52.8, respectively. % And 60.6% by mass.

The last 40 days (third period: 148 to 188
The change in the amount of carbon in the aeration tank on day 3) hardly increased as indicated by the straight line 3. As described above, the sludge treatment rate in the third treatment period was 99% by mass.

As shown in FIG. 3 and Table 1, when the sludge treatment rate is low at 65% by mass or less, the pH of the activated sludge water in the aeration tank 12 is less than 5.

Therefore, in order to eliminate the total organic carbon in the surplus sludge that has been introduced, it is necessary to maintain the pH of the activated sludge water in the aeration tank 12 at 5 or more.

When the excess sludge is transferred from the adjusting tank 6 to the aeration tank 12 and the excess sludge is to be treated in the aeration tank 12, if the pH of the activated sludge water in the aeration tank 12 becomes less than 5 (in line 2) During the corresponding period, the total organic carbon content of the activated sludge water in the aeration tank 12 increases, and the sludge treatment rate deteriorates.

On the 138th day of the treatment, sodium hydrogen carbonate as a pH adjuster was added to the activated sludge water in the aeration tank 12,
The next day (139 days of treatment), the pH was measured to be 7
That's all. However, after the next day (139 days of treatment), the conditions were returned to the condition of not adding the pH adjuster of Comparative Example 2 (2nd stage) again, and the treatment was continued.
The pH of 5 could not be maintained, and the pH dropped to less than 5 on the 142th day of the treatment, which was the medium 2 days.

The activated sludge water in the aeration tank 12 and the adjustment tank 6
When the pH of the aeration tank 12 is adjusted by adding sodium hydrogencarbonate as an H adjuster (after 143 days), the aeration tank 12
Became 7 or more, and the sludge treatment rate in the aeration tank 12 increased.

As shown in FIG. 4 and Table 1, when the sludge treatment rate is low at 65% by mass or less, the ammonia nitrogen concentration of the activated sludge water in the aeration tank 12 exceeds 70 mg / L.

Therefore, in order to extinguish the total organic carbon in the surplus sludge introduced, it is effective to maintain the ammonia nitrogen concentration of the activated sludge water in the aeration tank 12 at 70 mg / L or less.

In the first stage, the concentration of the ammonia nitrogen in the activated sludge water in the aeration tank 12 is 50 mg / L or less and has not increased. In this first treatment period, the sludge treatment rate is 1
It was 00% by mass.

In the 2-1 and 2-2 periods, in which the ammonia nitrogen concentration of the activated sludge water in the aeration tank 12 was increased to more than 70 mg / L, the sludge treatment rate was reduced,
It was as low as 2.8% by mass and 60.6% by mass and 65% by mass or less.

The pH of the aeration tank 1 is adjusted by adjusting the pH in the adjustment tank 6.
In the third stage in which the pH of the activated sludge water in 2 was adjusted, the ammonia nitrogen concentration of the activated sludge water in the aeration tank 12 could be dramatically reduced, and the sludge treatment rate was restored to 99% by mass.

Therefore, the treatment of ammonia nitrogen is important for improving the treatment rate of activated sludge.

As shown in FIG. 5 and Table 1, regarding the activated sludge water in the aeration tank 12 in the first stage, not only the ammonia nitrogen concentration is as low as 0 to 60 mg / L, but also the nitrate nitrogen concentration is 0. ３００300 mg / L, not so high.

Regarding the activated sludge water in the aeration tank 12 in the 2-1 and 2-2 periods, the average concentration of ammonia nitrogen during the treatment period was 80 in the 2-1 period.
mg / L and 140 mg / L in the 2-2 stage, and the average concentration of nitrate nitrogen during the treatment period was 350 mg / L in the 2-1 stage and 500 m in the 2-2 stage, respectively.
g / L, which is higher than the first period.

Until the 2-2 period, the relationship between the transition of the nitrate nitrogen concentration of the activated sludge water in the aeration tank 12 and the sludge treatment rate is determined by the relationship between the ammonia nitrogen concentration and the sludge treatment rate. The relationship is almost the same.

However, in the activated sludge in the aeration tank 12 in the third stage, the concentration of ammonia nitrogen is decreased, but the concentration of nitrate nitrogen is high and gradually increased.

Incidentally, nitrate nitrogen can be easily reduced by intermittent aeration or the like, but the sludge treatment rate cannot be improved by itself.

From this, it is presumed that the nitrate nitrogen concentration of the activated sludge water in the aeration tank 12 is not a direct cause of the sludge treatment rate.

FIG. 6 summarizes FIG. 3 and FIG.
It is a graph which shows the relationship between pH and ammonia nitrogen concentration about activated sludge water in the inside.

As shown in FIG. 6 and Table 1, the activated sludge water in the aeration tank 12 in the first stage has a pH of 5 or more. On the other hand, although the ammonia nitrogen concentration is gradually increasing, it is not unilaterally increasing, and is as low as 70 mg / L or less even at the time of the increase.

The pH of the activated sludge water in the aeration tank 12 in the 2-1 and 2-2 stages is less than 5. On the other hand, the average concentration of ammonia nitrogen was 80 mg / L in the second stage and 140 mg / L in the second stage.
And increased monotonically.

In the activated sludge in the aeration tank 12 in the third stage, the pH becomes 7 or more, the ammonia nitrogen concentration is drastically reduced, and the ammonia nitrogen is reduced to approximately 10%.
0% treatment.

The following can be mentioned from these results.

In order to reduce or preferably eliminate the excess sludge by aeration, the pH of the aeration tank should be 5 or more, preferably 7 to
9, more preferably 7-8.

In order to reduce or preferably eliminate excess sludge in the aeration tank, it is necessary to oxidize and treat ammonia nitrogen generated in the aeration tank.

To maintain the pH of the aeration tank in the above range,
The pH may be adjusted in the aeration tank, but it is convenient to maintain the pH in the aeration tank in the above range by adjusting the pH in the adjustment tank. For this purpose, it is preferable to measure the pH of the aeration tank and feed that value back to the pH adjustment of the adjustment tank.

Example 3 and Comparative Example 3 As shown in Table 2, except that the aeration tank capacity and the like were different, an organic waste treatment facility having the same treatment flow as in FIG. Regarding the reference numerals of the parts and the respective members, the corresponding reference numerals of the respective parts and the respective members in FIG. 1 are used instead), and the excess sludge (organic waste) for the processing conditions of Example 3 and Comparative Example 3 shown in Table 2. ) Was used as raw water for microbial treatment, and the results are shown in Table 2.

[0115]

[Table 2]

In the case of Comparative Example 3, the pH of the activated sludge in the aeration tank 12 became 5 or less, and as shown in Table 2, the ammonia nitrogen concentration of the activated sludge in the aeration tank 12 was 150 mg / L. 57. Carbon treatment rate (sludge treatment rate)
It is 0% by mass, which indicates that neither ammonia nitrogen treatment nor organic carbon treatment can be performed.

On the other hand, in the case of Example 3, as shown in Table 2, the ammonia nitrogen concentration of the activated sludge water in the aeration tank 12 was 1.0 mg / L, and the carbon treatment rate was 100.
It is 0% by mass, indicating that organic carbon and ammonia nitrogen can be simultaneously treated in the same treatment tank.

Next, the results of Examples and Comparative Examples in which various organic wastes other than excess sludge were treated with microorganisms are shown below.

Examples 4 to 6 and Comparative Examples 4 and 5 As shown in Tables 3 and 4, an organic waste treatment facility having a treatment flow similar to that of FIG. (Hereinafter, the reference numerals of the corresponding parts, the respective members, etc. in the processing flow will be replaced with the corresponding reference numerals of the respective parts, the respective members, etc. in FIG. 1). Regarding the treatment conditions of Comparative Examples 4 and 5, microbial treatment was performed using livestock urine or livestock manure (organic waste) as raw water, and the results are shown in Tables 3 and 4.

[0120]

[Table 3]

[0121]

[Table 4]

In the case of Comparative Examples 4 and 5, the pH of the activated sludge water in the aeration tank 12 became 5 or less, and as shown in Table 4, the concentration of ammonia nitrogen in the activated sludge water in the aeration tank 12 decreased. 390 mg / L and 900 mg / L
L and carbon treatment rates are 62.0 mass% and 55.
It is 0% by mass, which indicates that neither ammonia nitrogen treatment nor organic carbon treatment can be performed.

On the other hand, in Examples 4, 5 and 6, as shown in Table 3, the activated sludge aqueous ammonia concentration in the aeration tank 12 was 13 mg / L and 3 mg / L, respectively.
mg / L and 1.3 mg / L, the carbon treatment rates are 90.0% by mass, 94.0% by mass, and 92.0% by mass, respectively, and organic carbon and ammonia nitrogen are simultaneously treated in the same treatment tank. You can see that it has been processed.

Example 7 As shown in Table 5, an organic waste treatment facility provided with a treatment flow similar to that of FIG. 1 except that the aeration tank capacity and the like were different (hereinafter, each part and each member in the treatment flow) was used. For the reference numerals, etc., the corresponding parts in FIG. 1 and the reference numerals for the respective members are used instead), and garbage (organic waste) is used as raw water for microbial treatment under the conditions shown in Table 5, and the results are shown in a table. It is shown in FIG.

[0125]

[Table 5]

In Example 7, the garbage of the organic waste to be treated is a few meters by a disposer as a pretreatment.
After being crushed to a size of m, the material is further refined to a size of several tens of μm by a fine crusher (mill).

As shown in Table 5, the activated sludge aqueous ammonia concentration in the aeration tank 42 was 11.1 mg / L,
The carbon treatment rate was 100.0% by mass.
It can be seen that even when the organic waste to be treated is garbage as described above, organic carbon and ammonia nitrogen can be treated simultaneously in the same treatment tank.

Further, as shown in Table 5, the total organic carbon concentration of garbage, which is an organic waste to be treated, is 6000.
Since the concentration is as high as 0 mg / L, many components evaporate as carbon dioxide gas, nitrogen gas, water vapor and the like by biodegradation. As a result, in the next batch operation, the activated sludge water in the aeration tank 42 was not discharged out of the aeration tank 42, and even the supernatant liquid of the precipitation tank 38 discharged out of the system as treated water could be eliminated.

[0129]

According to the method for treating organic waste of the present invention, the treatment of ammonia nitrogen can be carried out simultaneously and rapidly with the treatment of organic carbon, suppressing the growth of activated sludge and generating excess sludge. Can be prevented. Therefore, there is no need to extract and reprocess sludge.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an organic waste treatment method of the present invention.

FIG. 2 In Examples 1 and 2 and Comparative Examples 1 and 2, the horizontal axis represents the number of treatment days for the cumulative input carbon amount and the total organic carbon amount of activated sludge water in the aeration tank (carbon amount in the aeration tank). It is a graph which shows the change made.

FIG. 3 shows the changes in the amount of carbon in the aeration tank and the pH of the activated sludge water in the aeration tank (pH in the aeration tank) in Examples 1 and 2 and Comparative Examples 1 and 2, with the number of treatment days on the horizontal axis. FIG.

FIG. 4 shows the number of treatment days in Examples 1 and 2 and Comparative Examples 1 and 2 for the amount of carbon in the aeration tank and the ammonia nitrogen concentration of the activated sludge in the aeration tank (the ammonia nitrogen concentration in the aeration tank). 7 is a graph showing the transition with the horizontal axis as.

FIG. 5 shows the ammonia nitrogen concentration in the aeration tank and the nitrogen nitrate concentration in the activated sludge water in the aeration tank (Nitrate nitrogen concentration in the aeration tank) in Examples 1 and 2 and Comparative Examples 1 and 2.
5 is a graph showing the transition of the number of processing days on the horizontal axis.

FIG. 6 is a graph showing the transition of the ammonia nitrogen concentration in the aeration tank and the pH in the aeration tank with the number of treatment days on the horizontal axis in Examples 1 and 2 and Comparative Examples 1 and 2.

[Explanation of symbols]

 2 wastewater treatment equipment 4 raw water tank 6 adjustment tank 8 sedimentation tank 10 pH adjuster tank 12 aeration tank 14 air diffuser 16 roots blower 18 air diffuser 20 roots blower 22 defoaming showering

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiro Kamogawa 11-2 Kamibahakodatemachi, Minami-ku, Kyoto-shi, Kyoto Kyoto B-3 11-2, Kyotoba Hakodatemachi, Minami-ku, Kyoto-shi, Kyoto City B-3 City Support Center B-3 Inside the Toyo Environmental Technology Research Institute Co., Ltd. (72) Inventor Shu Nakajima 11-2, Kyotoba Hokodate-cho, Minami-ku, Kyoto, Kyoto City Business Supporting Plant B-3 Inside the Toyo Environmental Technology Research Institute Co., Ltd. (72) Inventor Nakatani Creative Kyoto City Business Supporting Plant B-3 Kyoto Toyo Environmental Technology Research Co., Ltd. In-house (72) Inventor Hidehiko Kinoshita Kyoto Metropolitan Foundation for Business Establishment 11-2 Kamibahakodatemachi, Minami-ku, Kyoto, Kyoto F-3 (Reference) 4D004 AA02 AA03 CA19 CB03 CC02 CC07 4D040 BB01 BB91 4D059 AA01 AA03 AA07 BA03 BA22 BF13 BF14 BK12 DA01 EB05

Claims (6)

[Claims] 1. A method for treating organic waste, wherein organic waste is added to activated sludge water in an aeration tank and air bubbles are introduced into the activated sludge water. And a pH adjuster, as well as biodegradation of organic carbon in activated sludge water, endogenous respiration of microorganisms, nitrification of ammonia nitrogen, and oxygen more than the amount of oxygen required for autooxidation of microorganisms into activated sludge water. Supply, maintain the pH of the activated sludge water in the aeration tank at 5 or more, simultaneously treat the carbon and nitrogen in the same tank, and add and aerate the organic waste to the activated sludge water in the aeration tank. A method for treating organic waste, wherein the activated sludge water is discharged to the outside of the tank within a range that does not reduce the concentration of the proliferating nitrifying bacteria. 2. The method for treating organic waste according to claim 1, wherein the pH of the activated sludge water in the aeration tank is maintained at 7 or more. 3. The organic waste is excess sludge.
3. The method for treating organic waste according to claim 1. 4. The method for treating organic waste according to claim 1, wherein the organic waste is garbage or livestock manure. 5. The addition of organic waste to the activated sludge water in the aeration tank and the discharge of the activated sludge water out of the aeration tank when necessary in a batch mode, and the number of nitrifying bacteria is determined by nitrification at the end of the previous batch. The method for treating organic waste according to claim 1, wherein the organic waste is added to the activated sludge water in the aeration tank and the activated sludge water is discharged out of the aeration tank while maintaining the number of bacteria or more. 6. The method for treating organic waste according to claim 5, wherein the amount of activated sludge discharged to the outside of the aeration tank in each batch is not more than one seventh of the total amount of activated sludge in the aeration tank. .