JP5139033B2 - Waste water treatment method and waste water treatment equipment - Google Patents

Description

  The present invention relates to a wastewater treatment method and a wastewater treatment apparatus for performing wastewater treatment by intermittently aeration of an aeration tank every predetermined time.

Conventionally, an intermittent aeration method is known as a wastewater treatment method. This intermittent aeration method is a method of performing nitrification denitrification by alternately creating an aerobic state and an anaerobic state by repeating aeration and non-aeration (aeration stop) in the same tank.
As a conventional technique related to such an intermittent aeration method, the applicant of the present invention disclosed in Patent Documents 1 and 2 is an aerobic treatment method using an activated sludge method for anaerobic wastewater (anaerobic treatment water), which is anaerobic. Activated sludge treated water by guiding the treated water to the activated sludge tank, intermittently aeration of the activated sludge tank, forming an oxygen-free state at the time of aeration stop, performing nitric acid respiration, and promoting activated sludge floc formation The water quality of the activated sludge tank is improved and filamentous bacteria and actinomycetes are prevented from predominating in the activated sludge tank. Further, the scum of the inflow portion to the settling tank provided downstream of the activated sludge tank, and the levitation by denitrification A waste water treatment method for preventing scum is disclosed.

  In patent documents 1 and 2, in an aerobic treatment (activated sludge treatment) performed on anaerobic treated water, when only anaerobic treated water is treated while intermittently performing aeration (Example 1), aeration is always performed. Compare the effects of treating only anaerobic treated water (Comparative Example 1) and treating a mixture of anaerobic treated water and general wastewater (drained water that has not been anaerobically treated) while performing aeration (Comparative Example 2) Then, the change with time of the drainage transparency after the aerobic treatment in each example was examined and described in paragraph [0017] as follows.

  The transparency after the fifth day of operation (February 25) is the same as in Example 1 at both appropriate load (0.12 kgBOD / kgMLVSS · day) and low load (0.06 kgBOD / kgMLVSS · day)> Comparative Example 2> Higher in the order of Comparative Example 1. In particular, at the time of low load, a remarkable difference is observed in the degree of transparency between Example 1 and Comparative Examples 1 and 2. Therefore, the degree of transparency does not decrease even under a low load under the conditions of Example 1. I understood. Further, in Example 1, the operation was completely stopped during the holidays (2 to 3 days), but the transparency after the third day after the restart was stable at 80 to 100 cm. However, although the degree of transparency once decreased on the second day after re-startup, the extent of the decrease became smaller as the number of operating days passed.

JP 2004-174411 A JP 2006-88158 A

  As described in the cited references 1 and 2 mentioned above, in the intermittent aeration method, when the wastewater treatment is stopped for a long time during a holiday and then restarted, the transparency may be deteriorated. There's a problem.

  The present invention has been made in view of the above points, and even when the wastewater treatment is completely stopped and restarted, the T-P value is suppressed without affecting the transparency. An object of the present invention is to provide a wastewater treatment method and a wastewater treatment apparatus capable of performing stable wastewater treatment while reducing the number of working days of the tertiary treatment facility.

In order to achieve the above object, the wastewater treatment method of the present invention includes an adjustment tank for receiving wastewater, an acid generation tank for anaerobically treating the wastewater supplied from the adjustment tank, and promoting acid fermentation, and the acid generation An anaerobic reaction tank that converts alcohol and organic acid produced by acid fermentation contained in the wastewater supplied from the tank into acetic acid and hydrogen and then converts it to methane, and drains the wastewater by contacting it with sludge and intermittently aeration The wastewater treatment facility is equipped with an aeration tank that biochemically decomposes organic matter in the tank and a sedimentation tank that separates the sludge mixed solution supplied from the aeration tank into sludge and supernatant liquid. When the wastewater treatment is resumed from the state where there is drainage in the aeration tank with the wastewater treatment stopped, the inflow of wastewater into the aeration tank and the start of aeration in the aeration tank substantially simultaneously performed, the Upon resumption of water treatment, and wherein the substantially be started simultaneously and BOD uptake by sludge by uptake and drainage inflow of phosphorus into the sludge by the aeration in the aeration tank.
According to the present invention, phosphorus is taken into sludge by carrying out aeration. By simultaneously performing drainage input, BOD uptake by sludge is started at the same time. Therefore, temporary self-nitrification can be avoided and pin flocs are reduced. Due to the decrease in pin floc, the rise in TP in the treated water is suppressed, and stable waste water treatment can be performed without affecting the transparency.

In order to achieve the above object, the wastewater treatment apparatus of the present invention includes an adjustment tank for receiving wastewater, an acid generation tank for anaerobically treating the wastewater supplied from the adjustment tank and promoting acid fermentation, and the acid generation An anaerobic reaction tank that converts alcohol and organic acid produced by acid fermentation contained in the wastewater supplied from the tank into acetic acid and hydrogen and then converts it to methane, and drains the wastewater by contacting it with sludge and intermittently aeration The wastewater treatment facility is equipped with an aeration tank that biochemically decomposes organic matter in the tank and a sedimentation tank that separates the sludge mixed solution supplied from the aeration tank into sludge and supernatant liquid. a waste water treatment apparatus in the case of raising, the aeration means for aerating the wastewater in the aeration tank, the dosing means for introducing wastewater into the aeration tank, the aeration starts at the inflow and aeration tanks of waste water into the aeration tank and a control unit for controlling, When the wastewater treatment is resumed from the state where there is drainage in the aeration tank while the wastewater treatment is stopped, the control device performs the inflow of wastewater into the aeration tank and the start of aeration in the aeration tank almost simultaneously, When the wastewater treatment is resumed, the uptake of phosphorus into the sludge by aeration and the uptake of BOD by the sludge by inflow of wastewater are started substantially simultaneously in the aeration tank .
According to the present invention, phosphorus is taken into sludge by carrying out aeration. By simultaneously performing drainage input, BOD uptake by sludge is started at the same time. Therefore, temporary self-nitrification can be avoided and pin flocs are reduced. Due to the decrease in pin floc, the rise in TP in the treated water is suppressed, and stable waste water treatment can be performed without affecting the transparency.

  According to the present invention, even when the wastewater treatment is restarted from the state where the wastewater treatment is stopped, or even when the wastewater load is switched from the low load state to the high load state, the transparency is affected. It is possible to stably treat the waste water without any problems. Further, the TP value can be suppressed, and the number of working days of the tertiary processing facility can be reduced.

Hereinafter, embodiments of the wastewater treatment method and apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a wastewater treatment facility equipped with the wastewater treatment apparatus of the present invention.
As shown in FIG. 1, the wastewater treatment facility performs an acid fermentation by anaerobically treating the effluent supplied from the adjustment tank 1 and the adjustment tank 1 for receiving the wastewater generated in a beverage manufacturing process such as a beer factory. The acid generation tank 2 to be advanced, the anaerobic reaction tank 3 that converts the alcohol and organic acid produced by the acid fermentation contained in the wastewater supplied from the acid generation tank 2 into acetic acid and hydrogen, and then converts them into methane, and the wastewater as sludge An aeration tank 4 in which the organic matter in the waste water is biochemically decomposed by being aerated intermittently, a precipitation tank 5 for separating the sludge mixed solution supplied from the aeration tank 4 into sludge and a supernatant, and a precipitation And a pressurized flotation separation tank 6 for separating the sludge agglomerated in the tank 5 by flotation under pressure.

  As shown in FIG. 1, two systems of the adjustment tank 1, the anaerobic reaction tank 3, the aeration tank 4, the precipitation tank 5, and the pressurized flotation separation tank 6 are provided.

  In addition, the waste water in the adjustment tank 1 can be supplied to the aeration tank 4 without passing through the acid generation tank 2 and the anaerobic reaction tank 3 by the first bypass pipe BP1. In addition, the second bypass pipe BP2 is installed so that the final treatment in the sedimentation tank 5 does not require the treatment in the pressurized flotation separation tank 6.

  In the wastewater treatment facility configured as shown in FIG. 1, factory wastewater is once received in the adjustment tank 1, and the adjustment tank 1 performs flow rate adjustment and water quality homogenization. Although the amount of wastewater generated varies depending on the time zone, in principle, the wastewater is injected into each downstream tank at a constant flow rate as much as possible. In the acid production tank 2, acid fermentation is advanced by anaerobically treating the wastewater supplied from the adjustment tank 1 at a constant flow rate. That is, macromolecular organic substances (carbohydrates, proteins, lipids) in the wastewater are decomposed into sugar, alcohol, organic acid, carbon dioxide and the like by hydrolysis and acid generation. Material conversion proceeds until the stage of acid generation, but the COD (chemical oxygen demand) of the wastewater does not decrease. In the anaerobic reaction tank 3, after the alcohol or organic acid produced in the acid generation tank 2 is decomposed into acetic acid and hydrogen, finally, acetic acid and hydrogen are converted into methane. If there is sulfate, the reduction to hydrogen sulfide proceeds in parallel. By this conversion to methane gas, organic substances are removed from the wastewater, and the COD of the wastewater is reduced.

  The aeration tank 4 is a facility that forms the center of a treatment facility based on the activated sludge process. The aeration tank 4 is sufficiently brought into contact with sludge by drainage, and is aerated to supply oxygen necessary for metabolism of organic matter, thereby creating a turbulent state in the tank. . Under such conditions, organic matter is biochemically decomposed to purify wastewater. The activated sludge method is a method in which aerobic microorganisms process the organic matter in the wastewater. At this time, the microorganisms require oxygen, so an aeration tube is installed at the bottom of the aeration tank, and air is finely discharged from the aeration tube. Oxygen is dissolved in the waste water in the aeration tank by ejecting it into the tank as a simple bubble.

  In the aeration tank, a mass of several tens of μm to several mm containing a large amount of aerobic microorganisms floats at a concentration of 3500 to 5000 mg / l. This lump is called activated sludge floc, and the microorganisms contained here are mainly composed of many kinds of bacteria such as Zooglea, Pseudomonas, and Bacillus, and also include protozoa such as worms and rotifers.

  The settling tank 5 connected to the aeration tank 4 has a role of separating the treated water obtained by decomposing the organic matter in the aeration tank 4 and the floc of activated sludge by natural sedimentation. That is, in the settling tank 5, the sludge mixed liquid is allowed to stand for a predetermined time, the floc of activated sludge is allowed to settle, and the supernatant liquid is discharged as treated water. A part of the activated sludge accumulated in the settling tank 5 is returned to the aeration tank 4 by a sludge pump (not shown) and again used as a seed sludge for the treatment. A part of the activated sludge accumulated in the settling tank 5 is taken out of the system as surplus sludge.

  The pressurized flotation separation tank 6 raises the agglomerated sludge under pressure and separates it from water. In the pressurized levitation method, the suspended solids are wrapped with fine air contained in pressurized water, and the floc is made lighter than water to be separated by levitation.

  FIG. 2 is a schematic diagram showing details of the waste water treatment apparatus including the aeration tank 4 and its peripheral devices. As shown in FIG. 2, the aeration tank 4 has a three-pass configuration, and the wastewater flowing into the aeration tank 4 flows in the order of one pass, two passes, and three passes. Each path in the aeration tank 4 is provided with a number of aeration pipes 11, and each of the aeration pipes 11 is connected to the aeration blower 12 via a conduit 21 and opening / closing valves V <b> 1 and V <b> 2. The air diffuser 11 and the aeration blower 12 constitute an aeration means for aerating the waste water in the aeration tank 4. A large number of stirrers 13 are provided in the first pass and the second pass in the aeration tank 4.

The aeration tank 4 is provided with a number of input ports 14 for supplying drainage (raw water) to each path in the aeration tank 4. In addition, drainage (raw water) is supplied to each input port 14 via a pipeline 22 and an inflow valve _VIN- 1 and _VIN- 2. The input port 14 and the inflow valves V _IN −1 and V _IN −2 constitute an input unit that inputs waste water into the aeration tank 4. The operation of the aeration blower 12, the stirrer 13, the on-off valves V 1 and V 2 and the inflow valves V _IN −1 and V _IN −2 is controlled by the control device 15. In FIG. 2, the diffuser tube 11, the stirrer 13, and the inlet 14 that are operating are indicated by solid lines, and the stopped diffuser tube 11, the agitator 13, and the inlet 14 are indicated by dotted lines.

In the waste water treatment apparatus configured as shown in FIG. 2, the control device 15 performs control so that the opening operation of the inflow valve V _IN −1 or V _IN −2 and the start of the aeration blower 12 are performed simultaneously or substantially simultaneously. To do. By this control, the inflow of waste water into the aeration tank 4 and the start of aeration in the aeration tank 4 can be performed simultaneously or substantially simultaneously. This control is effective when the wastewater treatment is restarted from the state where the wastewater treatment is stopped. That is, when the wastewater treatment is resumed from the state where the wastewater treatment is stopped, the control device 15 performs the opening operation of the inflow valve V _IN -1 or V _IN -2 and the start of the aeration blower 12 simultaneously or substantially simultaneously. Thus, the inflow of wastewater into the aeration tank 4 and the start of aeration in the aeration tank 4 are performed simultaneously or substantially simultaneously.

Next, the case where the wastewater treatment is restarted from the state where the wastewater treatment is stopped will be described by comparing the conventional treatment method and the present invention.
In the wastewater treatment facility shown in FIG. 1 and FIG. 2, the quality of the discharged water did not change during normal continuous treatment, but TP (total phosphorous) increased during startup after intermittent treatment. The tendency to do was seen.
Initially, at the time of start-up, aeration was preceded and wastewater (raw water) was introduced when the target DO (dissolved oxygen) was reached.
When various tests were conducted, aeration and raw water input (drainage input) were performed simultaneously (input of raw water before DO was not at the target value), thereby suppressing an increase in TP and tertiary treatment equipment. (Pressurized flotation separation tank) is not required. In addition, during the current total amount anaerobic treatment test, the transparency was stable while suppressing the TP of the discharged water, and the treatment condition was good.

It is thought that the following sludge mechanism is the reason why the increase in TP was suppressed by carrying out aeration and raw water input simultaneously.
That is, during normal processing (aerobic state), phosphorus is taken into sludge. When the treatment is stopped (anaerobic state), phosphorus that has been taken into sludge is released.

  In the conventional treatment method, phosphorus is taken into sludge by performing aeration. Since raw water is not input until there is a target DO value (no load), sludge self-nitrification occurs temporarily. As a result, sludge is dismantled and pin flocs increase. Since phosphorus is taken into the pin floc, the TP of the treated water rises.

  On the other hand, in this invention, phosphorus is taken in into sludge by implementing aeration. By introducing raw water at the same time, BOD uptake by sludge is started at the same time. Therefore, temporary self-nitrification can be avoided and pin flocs are reduced. Due to the decrease in pin floc, the rise in TP in the treated water is suppressed, and stable waste water treatment can be performed without affecting the transparency.

The above-described control is effective when the drainage load is switched from a low load state to a high load. That is, when the drainage load is switched from the low load state to the high load, the control device 15 performs the opening operation of the inflow valve _VIN- 1 or _VIN- 2 and the start of the aeration blower 12 simultaneously or substantially simultaneously. To control. By this control, the inflow of waste water into the aeration tank 4 and the start of aeration in the aeration tank 4 are performed simultaneously or substantially simultaneously. Also in this case, as described above, an increase in TP in the treated water is suppressed, and stable drainage treatment can be performed without affecting the transparency.

表１に示されるように、放流水の月平均Ｔ−Ｐ（ｐｐｍ）は、１０月を除き０．９ｐｐｍから１．５ｐｐｍの範囲に入っており、処理水中の総リン量の上昇が抑えられている。３次処理設備（加圧浮上装置）の稼働タイミングは、比較例である３月から７月の間は４月を除き、週初めの立上げ時にはほとんど稼働させた。一方、実施例である８月から１２月の間は、設備を保護するための暖機目的で稼働する時及び処理状況が悪化した時のみ３次処理設備を稼働させた。また透視度（月平均）の数値も比較的安定した透視度が得られた。立上げ時の透視度も、月平均の透視度と比較してみるとほぼ同様の数値が得られ、排水処理を完全に停止した後に再度立上げても透視度が落ちなかった。
実施例中の１０月のデータに関しては、良好な結果が得られなかったが、これは春、秋に水温の変化などにより汚泥菌相が変化したためと考えられる。図３に、上記のものと同様の設備で２００５年及び２００６年に実施された排水処理の際の透視度の変化をグラフで示す。２００５年は、上記比較例とほぼ同様の立上げ方法で実施した。図３の２００５年（破線で示す）、２００６年（実線で示す）の年間の透視度変化を表すグラフから明らかであるように、春先また秋、特に１０月の透視度が低くなる傾向があった。 (Examples and Comparative Examples)
The average TP (total phosphorus) amount in the effluent after drainage treatment in this example and the comparative example, the tertiary treatment amount, the working days of the tertiary treatment equipment (pressurization flotation device), the transparency, and the startup time The transparency data is shown in Table 1. This comparative test was conducted from March to December 2006.
In the example, at the time of start-up in the intermittent treatment, aeration and raw water were simultaneously introduced into the aeration tank, that is, raw water was introduced before the DO value reached the target value (implemented from August to December).
In the comparative example, when the intermittent treatment was started, aeration was performed in advance, and raw water was added when the target DO value was reached (from March to July).
Here, two aeration tanks having a volume of 3,550 m ³ were used, and precipitation tanks having an area of 754 m ² and 452 m ² were used. Incidentally, the volume of the adjustment tank 9,800M ³ the sum of two systems, the volume of the acid generating tank 3,500m ^3, anaerobic reaction vessel and the volume of the two systems use with one system was 1,500 m ^3. A pressurized flotation separation tank was used as the tertiary treatment facility.

As shown in Table 1, the monthly average TP (ppm) of the discharged water is in the range of 0.9 ppm to 1.5 ppm except for October, and the increase in the total phosphorus amount in the treated water can be suppressed. ing. The operation timing of the tertiary treatment equipment (pressure levitation device) was almost in operation at the beginning of the week except for April between March and July, which is a comparative example. On the other hand, during the period from August to December, which is an example, the tertiary processing equipment was operated only when it was operated for warm-up purposes to protect the equipment and when the processing status deteriorated. In addition, the degree of transparency (monthly average) was also relatively stable. Compared with the monthly average transparency, the same degree of transparency was obtained at the time of startup, and the transparency did not drop even when the wastewater treatment was stopped completely and started up again.
Regarding the October data in the examples, good results were not obtained, but this is considered to be due to changes in the sludge microflora due to changes in the water temperature in spring and autumn. FIG. 3 is a graph showing changes in the degree of transparency during wastewater treatment carried out in 2005 and 2006 using the same equipment as described above. In 2005, the start-up method was almost the same as the comparative example. As is apparent from the graph showing the change in the transparency of the year 2005 (shown by a broken line) and 2006 (shown by the solid line) in FIG. It was.

FIG. 1 is a schematic view showing a wastewater treatment facility equipped with the wastewater treatment apparatus of the present invention. FIG. 2 is a schematic diagram showing details of a wastewater treatment apparatus including an aeration tank and its peripheral devices. FIG. 3 is a graph showing a year-round change in transparency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Adjustment tank 2 Acid production tank 3 Anaerobic reaction tank 4 Aeration tank 5 Precipitation tank 6 Pressurization flotation separation tank 11 Aeration pipe 12 Aeration blower 13 Stirrer 14 Inlet 15 Controllers 21 and 22 Lines V1 and V2 Open / close valve V _IN -1, V _IN -2 Inlet valve

Claims (2)

An adjustment tank for receiving waste water, an acid generation tank for anaerobically treating the waste water supplied from the adjustment tank to advance acid fermentation, and acid fermentation contained in the waste water supplied from the acid generation tank An anaerobic reaction tank that converts alcohol or organic acid into acetic acid and hydrogen and then converts to methane; an aeration tank that contacts wastewater with sludge and aerated intermittently to biochemically decompose organic matter in the wastewater; and A wastewater treatment method for stopping and re-starting wastewater treatment in a wastewater treatment facility comprising a sedimentation tank that separates sludge mixed liquid supplied from an aeration tank into sludge and supernatant liquid ,
When the wastewater treatment is resumed from the state in which there is drainage in the aeration tank with the wastewater treatment stopped, the inflow of wastewater into the aeration tank and the start of aeration in the aeration tank are performed substantially simultaneously, and when the wastewater treatment is resumed In the aeration tank, the wastewater treatment method is characterized in that the uptake of phosphorus into the sludge by aeration and the uptake of BOD by the sludge by inflow of wastewater are started substantially simultaneously . An adjustment tank for receiving waste water, an acid generation tank for anaerobically treating the waste water supplied from the adjustment tank to advance acid fermentation, and acid fermentation contained in the waste water supplied from the acid generation tank An anaerobic reaction tank that converts alcohol or organic acid into acetic acid and hydrogen and then converts to methane; an aeration tank that contacts wastewater with sludge and aerated intermittently to biochemically decompose organic matter in the wastewater; and A wastewater treatment apparatus for stopping and restarting wastewater treatment in a wastewater treatment facility equipped with a sedimentation tank that separates sludge mixed liquid supplied from an aeration tank into sludge and supernatant liquid,
Comprising a aeration means for aerating the wastewater in the aeration tank, the dosing means for introducing wastewater into the aeration tank, and a control device for controlling the aeration initiation at the inflow and aeration tanks of waste water into the aeration tank,
When the wastewater treatment is resumed from the state where there is drainage in the aeration tank with the wastewater treatment stopped, the control device performs the inflow of wastewater into the aeration tank and the start of aeration in the aeration tank almost simultaneously, The wastewater treatment apparatus, wherein when the wastewater treatment is resumed, the uptake of phosphorus into the sludge by aeration and the uptake of BOD by the sludge by inflow of wastewater are started substantially simultaneously in the aeration tank .

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