JP3020456B2 - Organic wastewater treatment method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating organic wastewater, and more particularly to a method for measuring a biochemical oxygen demand (hereinafter referred to as BOD) and a chemical oxygen demand (hereinafter referred to as COD). The present invention relates to a method and an apparatus for treating activated sludge. The organic wastewater treatment method and apparatus of the present invention, conventionally, food industry wastewater treated with activated sludge represented by a standard activated sludge treatment method or long-time aeration treatment method, slaughtering, livestock wastewater, fishery processing wastewater, It can be used for the treatment of almost all organic wastewater such as leather wastewater, paint wastewater and human waste.

[0002]

2. Description of the Related Art As a method for treating organic wastewater, a method utilizing the activity of microorganisms in water is extremely effective, and known methods include an aeration lagoon method, a trickling filter method, a rotating disk method, and a contact aeration method. Have been. Among these, the standard activated sludge method is applied to sewage treatment and industrial wastewater treatment that discharges a large amount of organic wastewater. The activated sludge method uses the purification function of living organisms, so it can be adopted relatively easily because difficult operations and the use of dangerous chemicals are not required. On the other hand, the activated sludge ability maintains stable activated sludge capacity using living organisms. Some skill is required in operation management.

[0003]

Among organic wastewaters, there are many wastewaters which are apt to cause bulking (sludge swelling phenomenon) like food factory wastewaters. Activated sludge is discharged out of the system together with the treated water because solid-liquid separation of the sludge cannot be performed, and it is difficult to return the activated sludge.The activated sludge concentration in the aeration tank and the treatment performance often decrease significantly. At present, it is hindering operation management.

[0004] In addition, the wastewater from the food industry has many fluctuations in the quality, quantity, and season of the wastewater, which makes it difficult to operate the wastewater treatment apparatus. Therefore, during normal operation, in order to cope with these fluctuations, the BOD volume load is set to 0.5 to 1 kg-BO.
It must be operated at about D / m ³ · day, and there is a limit to the amount of organic matter decomposed and removed, so that the capacity and installation space of the activated sludge treatment tank are naturally large.

In a recently developed high-load activated sludge treatment apparatus, activated sludge treatment of a biofiltration system by a biofilm method typified by a fixed-bed treatment apparatus is carried out to obtain 2 to 5 kg / m ^3.
・ Processing is carried out with a daily BOD volume load. However, these are not suitable for packing equipment such as plastics, ceramics, etc. (filter medium), which is complicated due to the complexity of the apparatus, sludge blockage at the filter medium, generation of offensive odor, etc. It causes stable processing and makes operation management difficult.

[0006] On the other hand, activated sludge is usually protected by flocs, and it was naturally considered that the destruction of the flocs would impede the solid-liquid separation of the treated supernatant water due to the dispersion of the sludge. In addition, in order to perform stable high-load treatment, a sufficient amount of sludge and the amount of oxygen supply required for its maintenance and decomposition of organic matter are necessary, but the blowing method using a blower, compressor, etc. limits oxygen supply and oxygen dissolution efficiency. There is.

Accordingly, the present invention eliminates problems such as a reduction in the treatment capacity of organic wastewater treatment due to the formation of activated sludge flocs, difficulty in operation management, and an increase in the volume and setting space of a treatment tank, and the like. It is an object of the present invention to provide a method and an apparatus for effectively and efficiently treating odors.

[0008]

According to the present invention, in the activated sludge treatment of organic wastewater using a reactor having an inner cylinder therein, bacteria that do not form flocs in flocs formed by the bacteria in the sludge. Activated sludge flocs formed by entrapped or adsorbed are in a reactor liquid together with wastewater and air at a flow rate of 0.5 to 2.5 m ³ / m ² · sec by a solid-liquid mixing nozzle. By supplying it into the inner cylinder and once subdividing it into a dispersed state, it increases the gas-liquid contact efficiency of wastewater treatment and the contact efficiency between activated sludge and wastewater, and activates by supplying oxygen to activated sludge smoothly. Provided is a method for decomposing and removing organic matter in wastewater, wherein high-load wastewater treatment by sludge is enabled.

According to the present invention, a part of the sludge of the activated sludge reactor is drawn out by the activated sludge circulation pump, and is poured into the liquid in the reactor inner cylinder through the solid-gas-liquid mixing nozzle.
The inner cylinder and its inner cylinder are supplied inside the reactor so that high-load wastewater treatment with activated sludge excellent in solid-liquid separation can be performed by supplying the wastewater and air at a flow rate of about ^2.5 m ³ / m ² · sec. A wastewater treatment apparatus is provided, wherein a solid-gas-liquid mixing nozzle is provided at a position located in the liquid at the upper part.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a view showing a high-load activated sludge reactor having a gas-liquid mixing nozzle 1 according to the present invention.

According to the present invention, the organic wastewater to be treated flows in from the suction side of the reactor activated sludge circulation line 12 of the circulation pump 11 by the wastewater pump 13 and is returned from the circulating activated sludge and the direct sludge supply pump 14. The sludge flows into the inner cylinder 5 from the upper part of the reactor through the solid-liquid mixing nozzle 1 together with the sludge. The wastewater flowing down in the inner cylinder 5 comes into contact with activated sludge supplied with sufficient oxygen,
In the lower part of the reactor, organic substances are decomposed while rising outside the inner cylinder 5.

The treated water of the reactor flows into a sedimentation tank after removing bubbles in the activated sludge by gentle stirring in a degassing tank (not shown) in a later step. In the sedimentation tank, a firmer floc is formed and is separated into activated sludge and supernatant water, and then only the supernatant water (treated water) is discharged out of the system. on the other hand,
After the sludge deposited in the settling tank is concentrated, it is returned to the reactor by the pump 14 and flows into the activated sludge circulation line 12 on the suction side of the circulation pump 11.

The solid-gas-liquid mixing nozzle 1 has an air pipe 2 inside the nozzle, and wastewater and circulating activated sludge flow outside the air pipe 2. The tip 3 of the solid-gas-liquid mixing nozzle 1 may be tapered as shown in FIG. 2A schematically showing the structure of the solid-gas-liquid mixing nozzle, or may have a shape as it is as shown in FIG. Further, the tip 3 of the solid-gas-liquid mixing nozzle is submerged below the liquid level of the high-load activated sludge reactor (FIG. 1), and as shown in FIG. 1 and FIG. Located in. However, the position of the solid-gas-liquid mixing nozzle tip 3 may be any position above, at the same position as, or below the upper end 6 of the inner cylinder 5, and can be arbitrarily set and installed.
Similarly, the upper end 6 of the inner cylinder 5 is located below the liquid surface of the high-load activated sludge reactor, and can be arbitrarily set together with the lower end 7 of the inner cylinder 5.

The wastewater and activated sludge flowing through the solid-gas-liquid mixing nozzle 1 are introduced into the inner cylinder 5 in an extremely strong jet state together with air. At this time, the floc of the activated sludge is subdivided into a dispersed state, whereby the gas-liquid contact efficiency is extremely improved, and the supply of oxygen to the activated sludge is made smooth. The activated sludge of the downflow of the inner cylinder 5 is 0.5 to 2.5
It descends at a flow rate of m ³ / m ² · sec. This descending velocity is B
It can be arbitrarily set depending on the OD processing amount and the amount of air required accordingly.

Further, the activated sludge is supplied to the inner cylinder 5 as indicated by an arrow 9 in the mirror structure 8 at the lower part of the high-load activated sludge reactor (FIG. 1).
Rises on the outside, this time with a relatively gentle updraft. The activated sludge in the dispersed state undergoes self-granulation in this gentle state, forms firm flocs again, and becomes an activated sludge excellent in solid-liquid separation in the subsequent settling tank.

On the other hand, the activated sludge and a part of the air flowing in the ascending flow are caused by the descending flow from the solid-gas-liquid mixing nozzle 1 as indicated by arrows 1.
It is drawn in the direction of 0. Due to this action, a part of the air is reused as oxygen supplied to the activated sludge again without being emitted from the reactor. In addition, the activated sludge circulation pump 11 in the high-load activated sludge reactor draws the activated circulation sludge from the circulation activated sludge discharge line 15, and the wastewater supply pump 13 and the settling tank return sludge supply pump 14 from the suction side of the circulation pump 11. Waste water and return sludge are combined and solid-gas-liquid mixing nozzle 1 again
Through the inner cylinder 5.

The organic components in the wastewater are rapidly decomposed by these series of actions, and the treated water and activated sludge are reduced to 14%.
Then, the water flows into a precipitation tank via a deaeration tank at a later stage, and the treated supernatant water separated into solid and liquid is discharged there.

As described above, according to the present invention, the finely divided activated sludge flows downward at an extremely high flow rate while keeping the inside of the inner cylinder in a dispersed state, and then the activated sludge has a mirror surface structure. From the lower part of the reactor, the ascending flow flows outside the inner cylinder, and the activated sludge on the ascending flow forms a solid floc again by self-coagulation in a relatively gentle flow condition. Part of the activated sludge and air that has been drawn is drawn into the inner cylinder again by a strong downward flow from the solid-gas-liquid mixing nozzle, and the floc-shaped activated sludge is again subdivided, and at the same time, the air is reused as supply oxygen. Thus, a method for decomposing and removing organic substances in wastewater can be achieved.

As described above, according to the treatment apparatus and the treatment method of the present invention, the oxygen dissolving efficiency can be maintained at 2 to 5 times as high as that of the standard activated sludge treatment method. High load processing with a load of 20 to 30 kg / m ³ · day is possible.

On the other hand, in the processing apparatus according to the present invention, an extremely high oxygen dissolving efficiency can be obtained, and a load region (BOD volume load; 1-2 kg / m ^3.
Day) BOD volume load much more than 20-30 kg / m
^Since it can be operated in ³ days, it is possible to operate the device with high efficiency and the device capacity is compact,
Installation space is small. In addition, since there is no packing inside the reactor that induces clogging, the stability of the treatment can be improved and no odor is generated.

[0021]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples.

Example 1 In Example 1, wastewater from a food factory prepared food production process was used as the organic wastewater. First, a screen as a pre-processing step,
After removing contaminants in the wastewater and oil in the oil / water separation tank, 2,000 mg / L of BOD wastewater is supplied to the suction side of the reactor circulating pump by a pump, and the 270 liter high-load activated sludge treatment device is circulated together with the circulated activated sludge. To decompose organic matter in the wastewater. The activated sludge treated water was subjected to solid-liquid separation into activated sludge and supernatant water in a sedimentation tank after bubbles were removed in a degassing tank at a later stage to obtain treated water.

The BOD concentration of the treated water obtained as described above was measured and its removability was confirmed. In Example 1, the wastewater having a BOD concentration of 2,000 mg / liter had a BOD volume load of 5 to 20 kg. The treatment was carried out with an increased load by increasing the water flow rate up to / m ³ · day. The results are shown in FIG. 4 as the relationship between BOD volume load and BOD processability. FIG.
As described above, according to the method of the present invention, a removability of 90% or more was achieved in the processing property at a BOD volume load of 20 kg / m ³ · day.

Example 2 In Example 2, the treatment was carried out in the same manner as in Example 1 except that the type of organic wastewater was changed to wastewater from a slaughtering process for pigs and cattle whose main component was blood. After removing contaminants with a screen as a pretreatment step, a wastewater with a BOD of 1,500 mg / liter was supplied by a pump. In Example 2, a high-load activated sludge treatment apparatus 720 was used.
The treatment was performed in the same manner as in Example 1 using liters.

The BOD concentration of the treated water thus obtained was measured, and the removability was confirmed. In the second embodiment, the BOD
The wastewater having a concentration of 1,500 mg / liter was treated by increasing the load by increasing the flow rate until the BOD volume load reached 5 to ³⁰ kg / m ³ · day. The results are shown in FIG. 5 as the relationship between the BOD volume load and the BOD processability. According to the method of the present invention, as shown in FIG.
A removal rate of 85% or more was obtained in m ³ · day.

[0026]

As described above, according to the present invention, activated sludge treatment with stable treatment performance and easy operation management can be performed with an unprecedented high load treatment, and at the same time, equipment cost and installation space. Can be reduced. Further, the apparatus of the present invention can directly discharge treated water depending on the wastewater BOD depending on the wastewater BOD, so that there is no need to use unnecessary operation costs, and the post-treatment (standard activated sludge) depends on the discharge standard. Or coagulation treatment, and further tertiary treatment such as sand filtration and activated carbon), it is possible to purify to a river discharge level.

[Brief description of the drawings]

FIG. 1 is a view showing a high-load activated sludge reactor according to the present invention, in which a solid-gas-liquid mixing nozzle is installed above the reactor.

FIG. 2 is a view showing a solid-gas-liquid mixing nozzle according to the present invention, which has a double structure having an air nozzle inside the nozzle, and activated sludge flowing from a circulation pump flows outside the air nozzle; It is mixed at the nozzle tip.

FIG. 3 is a view showing a flow of activated sludge in a high-load activated sludge reactor according to the present invention.

FIG. 4 shows BOD volume load and B in Example 1 of the present invention.
It is a graph which shows the relationship of OD processability.

FIG. 5 shows BOD volume load and B in Example 2 of the present invention.
It is a graph which shows the relationship of OD processability.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Solid-gas-liquid mixing nozzle 2 ... Air pipe inside solid-gas-liquid mixing nozzle 3 ... Solid-gas-liquid mixing nozzle tip 4 ... Solid-gas-liquid mixing nozzle with a different tip shape 5 ... Inner cylinder inside reactor 6 ... Inner cylinder Upper end 7: Lower end of inner cylinder 8: Mirror structure at the lower part of high-load activated sludge reactor 9: Flow of activated sludge at the lower part of high-load activated sludge reactor 10: Flow of rising activated sludge 11: Activated sludge Circulation pump 12 ... Activated sludge circulation line 13 ... Waste water supply pump 14 ... Return sludge supply pump 15 ... Circulation activated sludge discharge line 16 ... Treatment water discharge line

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C02F 3/12 C02F 3/22

Claims (2)

(57) [Claims] In the activated sludge treatment of an organic wastewater using a reactor having an inner cylinder therein, bacteria that do not form flocs are entangled or adsorbed in flocs formed by bacteria in the sludge. The activated sludge floc formed as described above is mixed with a solid-gas-liquid mixing nozzle for 0.5-2.5.
Reactor with wastewater and air at flow rate of m ³ / m ² · sec
By supplying it to the inner cylinder in the liquid of the wastewater and once subdividing it into a dispersed state, thereby improving the gas-liquid contact efficiency of wastewater treatment and the contact efficiency between activated sludge and wastewater, and smoothing the supply of oxygen to activated sludge. A method for decomposing and removing organic matter in wastewater, wherein high-load wastewater treatment by activated sludge is enabled by performing the treatment. 2. A part of the sludge of the activated sludge reactor is drawn out by an activated sludge circulation pump, and is introduced into the liquid in the reactor inner cylinder through a solid-gas-liquid mixing nozzle in an amount of 0.5 to 2.5 m ³ / m ^2.
The inner cylinder and the liquid in the upper part of the inner cylinder are supplied inside the reactor so that they can be supplied together with the wastewater and air at a flow rate of sec.
A solid-gas-liquid mixing nozzle is provided at a position located in the wastewater treatment apparatus.