JPS62132597A - Method and device for treating waste water - Google Patents

Abstract

PURPOSE:To obtain a high denitrification effect by firstly carrying out aerobic treatment, supplying an org. material as a hydrogen donor into waste water, conducting anaerobic treatment, and then again performing aerobic treatment. CONSTITUTION:Waste water is supplied into the liq. mixture of activated sludge in the treating vessel 1 by a waste water supply part 2, and then the inside of the vessel 1 is aerated by an aerating means 3 and an agitating means 4. Then after aeration is stopped, a hydrogen donor soln. contg. org. materials is supplied from a feed part 5 to remove nitrogen in the supernatant liq. by the respiration of denitrifying bacteria, the soln. is mixed with sludge and the supernatant liq., and aeration is again carried out. Then aeration is stopped, solid is separated from liq., the deposited sludge is extracted by a pump P1, and the supernatant liq. is discharged as treated water by a drain mechanism consisting of a buoyancy body 6, a flexible pipe 7, a drainage pump P2, etc. Consequently, a high denitrification effect is obtained, and the supernatant liq. can be discharged without being mixed with solid components.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Applications The present invention relates to a wastewater treatment method and apparatus for decomposing organic matter in wastewater by microbial treatment.

B. Summary of the Invention The method of the present invention is a method for treating organic wastewater in a batch method using activated sludge, in which aerobic treatment is first performed;
Next, anaerobic treatment is performed by supplying organic matter as a hydrogen donor into the wastewater under anaerobic conditions, and then aerobic treatment is performed again to obtain a high denitrification effect.

The device of the present invention is a device for carrying out the method of the present invention, which uses a discharge mechanism that combines a floating body and a flexible pipe to discharge treated water suitable for a batch method.

C0 Prior Art and Problems to be Solved by the Invention Recently, the batch activated sludge method has been attracting attention mainly in small-scale wastewater treatment facilities. This method is a method in which wastewater flows into a mixed solution of activated sludge in a treatment tank, where aeration, solid-liquid separation, and supernatant water discharge are performed. ■ No bulking occurs. ■ Energy saving. ■ It has the advantage of not requiring advanced driving skills. Furthermore, compared to normal continuous operation, it is said that the denitrification and dephosphorization effects are higher because aeration and precipitation are repeated.

However, even though the batch activated sludge method has a high denitrification effect, this is based on empirical evidence, and there is no guarantee that a good denitrification effect will always be obtained when it is actually used. . Regarding the structure of the machine, an appropriate mechanism is required because it is not possible to use an overflow system like in normal continuous operation to discharge supernatant water.

The present invention has been made based on these circumstances, and aims to provide a batch-type wastewater treatment method with high denitrification effects while taking advantage of the advantages of conventional batch-type methods. .

Furthermore, the present invention provides a wastewater treatment method that allows such a wastewater treatment method to be carried out suitably, provides a high denitrification effect, and allows the supernatant liquid after treatment to be discharged without contamination with solid matter. The purpose is to provide a processing device.

Means and operation for solving problem D1 Before explaining the present invention in detail, first, FIG. 3 shows how an organic nitrogen compound such as protein is decomposed through nitrification reaction and denitrification reaction.

The bacteria circled in the figure are heterotrophic bacteria,
Other bacteria are autotrophic. Further, the reaction corresponding to the dotted line arrow is a nitrification reaction that proceeds under aerobic conditions, and the reaction corresponding to the chain line arrow is a ventricular reaction that proceeds under anaerobic conditions. The denitrification reaction can be expressed stoichiometrically as shown in the following equation.

2NO2-+ 3(H2)→N2 +20H-+2H2
0...(1)2NO3'-+ 5(H2)→N2+
2011″-+4) 120 ... (2) However, 11, (Equation 21 corresponds to nitrite respiration and nitrate respiration, respectively. (H2) of these reactions passes through the respiratory enzyme system in bacteria. However, most denitrifying bacteria use organic substances as hydrogen donors.

The present invention has been made with attention to these points, and involves aerobic treatment of wastewater in a treatment tank, and then anaerobic treatment by introducing a hydrogen donor liquid containing organic matter into the treatment tank. Then, by performing aerobic treatment again, the remaining organic matter is decomposed.

Specifically, the method of the present invention includes an inflow step of flowing wastewater into a mixed solution of activated sludge in a treatment tank, a first aeration step of aerating the inside of the treatment tank after this inflow step, and then aeration. After stopping, there is a mixing process in which a hydrogen donor liquid containing organic matter is mixed with the sludge and supernatant liquid in order to remove nitrogen in the supernatant liquid through the respiration of denitrifying bacteria in the sludge. a second aeration step in which the mixed liquid is aerated, a precipitation step in which the aeration is stopped and solid-liquid separation is performed, a sludge drawing step in which the sludge precipitated in this precipitation step is drawn out, and sludge separated in the precipitation step. and a discharge step of discharging the upper fjLi as total Li water.

The apparatus of the present invention also includes a treatment tank in which a mixed solution of activated sludge is stored, and a wastewater supply section that supplies wastewater from the treatment tank.
an aeration means and a stirring means each provided in the treatment tank;
A hydrogen donor fluid supply unit that supplies a hydrogen donor fluid containing organic matter to the treatment tank, a withdrawal pump that pulls out settled sludge from the treatment tank, and a discharge mechanism that discharges treated water in the treatment tank, the discharge mechanism consists of a buoyant body floating on the liquid surface of the treatment tank, a flexible pipe with one end provided with a water suction port attached to the buoyant body, and a filter section provided at the water suction port to remove all solid matter. and a water suction pump and a drainage valve connected to the other end of the flexible pipe.

E. Examples Examples of the method of the present invention will now be described together with an apparatus for carrying out the method. FIG. 1 is a longitudinal sectional view showing the device of the embodiment;
FIG. 2 is a process diagram showing the method of the example. 1 in Figure 1
is a treatment tank, 2 is a wastewater supply unit, B is a blower, 3 is an aeration means, 4 is a stirring means, and M is a motor. In the treatment tank 1, a mixed solution of activated sludge is preliminarily set at base water levels B, W, It accommodates up to L. In the embodiment, first, high-strength organic wastewater (hereinafter referred to as "raw water"), such as livestock barn wastewater, which has been previously diluted or anaerobically treated is allowed to flow into the treatment tank 1 to a predetermined water level, Stirring is carried out by the stirring means 4 to thoroughly mix the industrial wastewater and activated sludge. Note that the stirring step is not necessary if sufficient mixing is performed during the inflow step. Next, the blower B is fully driven to discharge air from the aeration means 3, thereby aerating the inside of the processing tank 1 for a predetermined period of time. In this example, the blower B and the aeration means 3 constitute an aeration means.

Through this aeration process, aerobic treatment is performed by aerobic bacteria in the activated sludge, organic matter in the wastewater is decomposed, and the nitrification reaction progresses. After sufficient aeration, organic matter has been sufficiently removed and nitrification has been sufficiently achieved, aeration is stopped and sludge is removed. Precipitate. After the settled sludge is brought under anaerobic conditions through this settling step, an appropriate amount of raw water, for example, is intermittently flowed into the treatment tank 1 from the hydrogen supply unit 5, and a mixing step is performed, for example, a step of stirring with the stirring means 4. The organic matter in the raw water, sludge, and supernatant liquid are completely mixed. The reason why raw water is introduced here is to replenish organic matter as a hydrogen donor, which will be described next. The denitrifying bacteria in the sludge extract hydrogen from the organic matter via the respiratory enzyme thread during the stirring process, and react this hydrogen with the nitrogen in the nitric acid and nitrous acid produced in the aeration process. is reduced to nitrogen gas and removed.

After that, aeration is performed again, and the remaining organic matter is removed by the aerobic bacteria group, and the ammonia component is nitrified.
Next, aeration is stopped and the sludge is allowed to settle.

In FIG. 1, Pl is a drawing pump as a sludge drawing means, and is installed in a sludge drawing pipe extending from the bottom of the treatment tank 1 to the outside. This drawing pump P1 draws out the sludge that has settled after the second aeration as surplus sludge, and then the supernatant water is discharged by the discharge mechanism described below.

Regarding sludge removal, the sludge retention time (SRT)
) is approximately 30 to 50 days.

As shown in FIG. 4, the discharge mechanism includes a buoyant body 6 floating on the liquid surface of the processing tank 1, and a part of a cover that is attached to the buoyant body 6 and serves as a cylindrical filter portion that is open at the bottom. , a flexible pipe 7 whose one end with a water inlet is inserted into the cover part 6 and whose outer diameter is slightly smaller than the inner diameter of the cover part 61; A drainage pump P2 connected to the other end of the flexible pipe 7 via a discharge pipe 71 so as to suck treated water from the water intake port, and a drainage pump P2 provided before and after the drainage pump P2, respectively. Manual valve 8 and electric valve 9 as discharge valves
It consists of In such a discharge mechanism, the flexible pipe 7 is always filled with treated water except during the discharge process, and by driving the drain pump P2 during the discharge process, supernatant water flows through the opening of the cover part 61. The water is sucked up from the flexible pipe 7 through the water intake port and is discharged to the outside as treated water. If the discharge mechanism shown in the figure is used, the supernatant liquid will be sucked in at a position lower than the liquid level, so scum floating on the liquid level will not get in, and the cover part 61 and flexible pipe There is a point 1j in which solid matter such as sludge is removed because water is absorbed through the gap between the pipes 9 and 7, and therefore no clogging of pipes 9 occurs. Further, the discharge speed of supernatant water can be adjusted by valves 8 and 9. H in the figure,
W and L are upper limit water levels.

In the above, organic substances such as methanol, acetic acid, or ethanol may be used as the hydrogen donor, but since these require running costs, it is preferable to use raw water because it is the cheapest. When using raw water, it is necessary to select it appropriately according to the composition of the raw water. Moreover, the amount of raw water supplied may be determined as follows.

In nitric acid respiration, the theoretical oxygen demand (Thop) corresponding to 5 (H2) hydrogen donors is stoichiometrically 5.
(0), 12.5 of Th and OD can be calculated as the theoretically donated hydrogen i. Considering Th0D Ki BOD5, BOD52.86 is required for No5-NIKyk denitrification.
K9 is required. Therefore, the supply amount can be determined from the raw water and treatment status.

In the present invention, although the control of each process shown in FIG. 2 may be performed using Silkens control with a predetermined time, each process may be controlled based on index values of water quality indicators such as oxidation-reduction potential (ORP) and pH. It is also possible to use control that determines the timing of , and more effective processing can be expected with the latter method.

F1 Application example of the present invention Although the present invention can be applied directly to relatively low-concentration organic wastewater, including domestic gray water, it can be appropriately treated. There are some aspects that are difficult to deal with regarding drainage. For this reason, it is desirable to subject wastewater to anaerobic or aerobic treatment before applying the present invention.
As shown in the figure. To briefly describe the system shown in the figure, highly concentrated organic waste water (flK water) from a livestock barn (1 oz +) is passed through a vibrating sieve 11 to remove impurities therein, and then stored in a raw water storage tank 12. The raw water from the raw water storage tank 12 is sent to the anaerobic tank 14 via the metering tank 13 at a constant flow rate, or by overflow at a flow rate depending on the amount of inflow into the raw water storage tank 12. . In this anaerobic tank 14, anaerobic treatment is performed using the sludge from the seed sludge culture tank 15, and methane fermentation treatment is performed using methane bacteria, and methane gas is recovered in the gas holder 16.

18 is an aerobic tank adapted to the wastewater treatment device of the present invention,
The waste water from the anaerobic tank 14 is sent continuously through the bypass or intermittently through the adjustment tank 17. Aerobic tank 1
Raw water is used as the hydrogen donor liquid used in step 8. The sludge settled in the aerobic tank 18 is pulled out and disposed of as surplus sludge, and is also transferred to the seed sludge culture tank 1 as seed sludge.
Sent to 5. Raw water is used as the culture solution for this type of sludge culture tank 15. Further, a portion of the treated water from the aerobic tank 18 is returned to the anaerobic tank 14 in order to enhance the denitrification effect.

G0 Effects of the Invention As described above, according to the present invention, aerobic treatment is first performed, then organic matter as a hydrogen donor is supplied to the wastewater under anaerobic conditions to perform the entire anaerobic treatment, and then aerobic treatment is performed again. Since we use a two-stage batch method that performs all treatments, the nitrogen in nitric acid and nitrite generated by aerobic treatment is sufficiently removed by anaerobic treatment, and the organic matter remaining after anaerobic treatment is removed. Since it is decomposed in the next step of aerobic treatment, it is possible to perform good wastewater treatment. Therefore, raw water can be used as the hydrogen donor fluid during anaerobic treatment, thereby reducing running costs. Further, according to the device of the present invention, the method of the present invention can be carried out suitably, and since a discharge mechanism that combines a buoyant body and a flexible pipe is used, water can always be absorbed from near the liquid level with a simple mechanism. Therefore, only the supernatant water can be taken out, and since the water suction pressure is constant regardless of the liquid level, the treated water from the aerobic tank can be smoothly discharged. There is no clogging in the filter section.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of the apparatus of the present invention, Fig. 2 is a process diagram showing an embodiment of the method of the invention, Fig. 3 is a schematic diagram of the nitrification/denitrification reaction, and Fig. 4 is a discharge machine. FIG. 5 is a vertical sectional view showing a part of the grip, and is a configuration diagram of an application of the present invention. DESCRIPTION OF SYMBOLS 1... Treatment tank, 2... Wastewater supply part, 3... Aeration means, B... Blower, 4... Stirring means, 5... Hydrogen donor body fluid supply part, 6...・Floating body, 7...Flexible pipe, P;...Drainage pump. Figure 1 Real money begging 3. . 2. Just... r good 1...
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7... Fushikishi Blue, -S Total °・Flore
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Claims (1)

[Claims] 1) An inflow step of flowing wastewater into the activated sludge mixture in the treatment tank, a first aeration step of aerating the inside of the treatment tank after this inflow step, and then stopping the aeration. A mixing process in which a hydrogen donor liquid containing organic matter is mixed with the sludge and supernatant liquid in order to remove nitrogen in the supernatant liquid through the respiration of denitrifying bacteria in the sludge, and a mixed liquid mixed by this mixing process. a second aeration step in which the aeration is aerated; a precipitation step in which the aeration is then stopped and solid-liquid separation is carried out; a sludge drawing step in which the sludge precipitated by this precipitation step is drawn out; and a supernatant liquid separated in the precipitation step. A wastewater treatment method characterized by comprising a discharge step of discharging as treated water. 2) A treatment tank in which a mixed solution of activated sludge is stored, a wastewater supply section that supplies wastewater to this treatment tank, an aeration means and a stirring means provided in the treatment tank, and hydrogen containing organic matter in the treatment tank. A hydrogen donor fluid supply unit that supplies a donor fluid, a withdrawal pump that withdraws settled sludge from the treatment tank, and a discharge mechanism that discharges treated water in the treatment tank, the discharge mechanism being configured to lower the liquid level of the treatment tank. a buoyant body floating on the buoyant body; a flexible pipe with one end provided with a water intake port attached to the buoyant body; a filter portion provided at the water intake port for removing solid matter; and the other end of the flexible pipe. A wastewater treatment device comprising a drain pump and a drain valve connected to each other.