JP2000126792A - Method of and apparatus for purifying highly concentrated organic sewage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a color from remaining in treated water, to almost dispense with the control of a sewage treatment apparatus, to suppress running cost and to perform stable purifying treatment in the purifying treatment of highly cone. org. sewage like barn sewage by activated sludge. SOLUTION: Highly cone. org. sewage 11 is charged in an oxidation trough type aeration tank 1. Photosynthetic bacteria 17 are added to the charged sewage 11 from a photosynthetic bacteria culture tank 2 and dilution water 16 is further supplied thereto from a dilution water tank 3 in order to set the concn. of sewage 11 to concn. to be treated suitable for activated sludge. Diluted sewage 11b is decomposed by activated sludge constituting bacteria and photosynthetic bacteria 17. The aeration tank 1 is allowed to stand in a batch to sediment activated sludge constituting bacteria and photosynthetic bacteria 17 and the supernatant liquid 20 is pumped up and sterilized in a disinfection tank 5 to be discharged as treated water 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method for purifying high-concentration organic wastewater such as livestock sewage and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art The treatment of organic sewage is generally performed by a purification treatment technique called an activated sludge method.

[0003] The activated sludge method, as shown in Fig. 3, comprises an aeration tank for decomposing organic wastewater by activated sludge microorganisms, and a settling tank for separating activated sludge and discharging treated water. In this method, generally, the operation of continuously feeding sludge into the aeration tank, discharging treated water from the sedimentation tank, and returning activated sludge from the sedimentation tank to the aeration tank (returned sludge) is performed for 24 hours. The aeration tank is a deep rectangular tank, and the air sent from the high pressure blower is made into fine bubbles by a diffuser and released from the bottom of the aeration tank (aeration type aeration system). Oxygen is supplied to the aeration tank.

However, the activated sludge method has a BOD concentration of several hundred to
This technology treats sewage with a relatively low concentration of about several thousand ppm, and is used for high-concentration organic sewage such as livestock sewage with a BOD concentration of thousands to tens of thousands of ppm, and organic sewage with a sharp change in concentration. On the other hand, there is a problem that the purification function becomes unstable and a color remains in the treated water after purification.

[0005] To solve such a problem, wastewater B
Specialized management is required such as management of OD concentration, adjustment of sewage input amount, adjustment of returned sludge amount, maintenance of high-pressure blower in rectangular water tank and cleaning of diffuser pipe.

However, it is a fact that livestock farmers, especially small-scale family-owned livestock farmers, cannot employ specialists in sewage treatment equipment management. Also, the most expensive running cost of the sewage treatment equipment in the activated sludge method is aeration of the aeration tank, but the electricity cost consumed by the high-pressure blower for this aeration puts a heavy burden on the operation of the livestock farmers. ing. As a result, the current situation is that the sewage treatment equipment cannot be adequately managed and the purification function is reduced or almost lost, and in the worst case, livestock sewage is discharged untreated. May even be.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention solves the problem that high-concentration organic wastewater such as livestock sewage is stably purified by activated sludge, and the color of the treated water remains. It is an object of the present invention to provide a sewage treatment method and a sewage treatment apparatus that require little management of the sewage treatment apparatus and have low running costs.

[0008]

The method for purifying high-concentration organic sewage according to the present invention comprises the steps of: charging high-concentration organic sewage into a batch-type oxidation ditch type aeration tank; adding photosynthetic bacteria to the sewage; And purifying the sewage with activated sludge and discharging the purified water.

In the method for purifying high-concentration organic sewage of the present invention, the sewage may be diluted so that the concentration of the sewage is such that the activity of bacteria constituting the activated sludge is high. it can.

The high-concentration organic sewage purification treatment apparatus according to the present invention is a high-concentration organic sewage treatment apparatus using activated sludge. A tank for culturing photosynthetic bacteria and adding the photosynthetic bacteria to the aeration tank.

Further, the purification apparatus for high-concentration organic sewage of the present invention may be configured such that a dilution water tank for supplying dilution water to the aeration tank is further provided.

The term "high-concentration organic sewage" refers to sewage having a high concentration of organic pollutants (high BOD concentration), such as sewage from cattle pens such as cows and pigs, or human waste.

The "batch type" is for a continuous type,
The aeration tank is stopped and the aeration tank is used as a sedimentation tank. Here, the aeration of the aeration tank is stopped about once a day, for example, about 1 to 4 hours, preferably about 3 hours, and activated sludge can be precipitated in the aeration tank. The continuous activated sludge method is a method that can reliably perform sewage treatment and is expected to have the most effective sewage treatment effect. is there. However, in the present invention, such a problem does not occur because the aeration tank is also used as a precipitation tank. Specifically, for example, aeration of the aeration tank is stopped at a predetermined time every day, the activated aeration tank is allowed to stand still, and activated sludge is settled, a predetermined amount of treated water is discharged, and the treated water is discharged. The wastewater from which solids have been removed by a sieve is put into an aeration tank, and aeration is continued again until a predetermined time on the next day. The amount of sewage to be charged is preferably one day in order to save the work of adjusting the amount of sewage to be charged.

The "oxidation groove type aeration tank" is a so-called oxidation ditch. The style of the oxidation groove type aeration tank is
Preferably, grooves having a depth of about 2 m and a width of about 3 to 4 m can be connected in an annular, elliptical, or strip shape. In the case of an aeration tank with a shallow depth of water, the aeration tank using a high-pressure blower and an aeration device has poor stirring efficiency and oxygen dissolving efficiency in the aeration tank. It is preferable to supply oxygen from. At the same time, it is preferable to use a tank capable of maintaining the horizontal flow rate of the sewage at about 30 cm / sec so that the sludge does not settle. It is more preferable that the groove is formed in an annular or elliptical shape so that the sewage flows by inertia.

The term "photosynthetic bacteria" refers to bacteria that grow by photoinorganic nutrition or photoorganism using light energy. Photosynthetic bacteria, in a narrow sense, have a single type of photochemical reaction system and do not have the ability to oxidize water to generate oxygen, Rhodospirillaceae (Rhodospirillaceae; Rhodospir
illum, Rhodopseudomonas, etc., Chromatium (Ch
romatiaceae; Chromatium, Ectothiorhodospira, etc.), but in the present invention, two kinds of photochemical systems operate in the photosynthetic reaction, and algae such as blue-green algae that perform green plant-type photosynthesis that oxidize water to generate oxygen. Means a photosynthetic bacterium in a broad sense, and is not particularly limited as long as it is suitable for purification treatment of high-concentration organic wastewater. It is preferable that the photosynthetic bacteria be cultured in a photosynthetic bacteria culture tank into which light enters, using the wastewater to be purified and the treated water.

The phrase "the concentration of the sewage is a concentration at which the activity of the bacteria constituting the activated sludge is increased" means that the bacteria constituting the activated sludge (hereinafter referred to as activated sludge bacterium) multiply and the organic sewage is efficiently treated. It means adjusting the concentration of sewage that can be decomposed. In other words, the activated sludge method is a purification treatment technology suitable for treating relatively low-concentration sewage. Therefore, if high-concentration livestock sewage is to be treated as raw water, the purification treatment function is reduced or the activated sludge composition is reduced. Since the bacteria may be killed and the purification process cannot be performed, it means that the sewage is diluted by supplying dilution water to the sewage having a high activity of the activated sludge constituent bacteria. In addition, in the case of livestock sewage, the concentration of sewage decreases in summer because the amount of sewage increases due to the water sprinkled by the heat of livestock in summer, but the amount of sewage decreases and the concentration of sewage increases in winter. Depending on the season,
Or the concentration of sewage fluctuates drastically due to the change in the number of livestock. Therefore, it means that the concentration change is absorbed and the concentration of the sewage to be subjected to the purification treatment is made constant at a concentration at which the activity of the bacteria constituting the activated sludge is increased. The concentration of the wastewater can be adjusted by supplying dilution water to the aeration tank. The amount of dilution water does not need to be determined each time by strict concentration control, and the concentration of wastewater is controlled by a control switch that automatically stops the supply of dilution water when the water level in the aeration tank becomes constant. It is simpler and preferable to adjust the concentration so that the activity is increased. The water level of the aeration tank after supplying the dilution water depends on the size of the aeration tank, but is preferably about 80 to 90% of the depth of the aeration tank.

[0017]

The photosynthetic bacterium added in the present invention is a bacterium that can inhabit sewage with a higher concentration than the activated sludge-constituting bacteria, and the photosynthetic bacterium absorbs such a high concentration load, The activated sludge constituent bacteria are inhabited, and the photosynthetic bacteria themselves are in a symbiotic relationship, being assisted by the activated sludge constituent bacteria.

Accordingly, the method and apparatus for purifying high-concentration organic wastewater of the present invention add a photosynthetic bacterium suitable for the treatment of high-concentration sewage and perform the purification treatment together with the bacteria constituting the activated sludge. The purification treatment function in treating high-concentration sewage such as livestock sewage and the like, in which the concentration changes drastically, can be remarkably stabilized as compared with the single treatment with the activated sludge constituent bacteria.

Further, the activated sludge-constituting bacteria alone cannot solve the problem of the color remaining in the treated water due to the inorganic salts, but the photosynthetic bacteria are excellent in assimilating the inorganic salts and are therefore transparent to the treated water. Can be achieved.

When the photosynthetic bacteria are self-cultured in the wastewater to be treated and the treated water, assimilation corresponding to each treatment facility can be obtained, so that a more stable purification function and color of the treated water can be obtained. The removal function is exhibited.

Since the method and apparatus for purifying high-concentration organic sewage of the present invention are of a batch type, the simple operation of leaving the aeration tank, discharging the treated water, and charging the sewage is repeated. Automatic operation can be easily performed using a switch or the like. Further, since it is not necessary to add a sedimentation tank, the management of returned sludge is not required, the construction cost is reduced, and the maintenance and management of the sewage treatment apparatus is simplified without oppressing the management of the livestock farmers.

The method and apparatus for purifying high-concentration organic sewage of the present invention use an oxidation-groove type aeration tank, so that the inside of the aeration tank has a horizontal water flow with little resistance to the sewage. Compared with a rectangular aeration tank in which the flow is a vertical water flow, the amount of power used to generate the water flow can be reduced. Further, the surface aeration device usually used in the oxidation groove type aeration tank does not need to pump air to the deep part of the aeration tank, so that electric power required for the pumping is not required. This makes it possible to reduce the electric power consumption to half or less as compared with a rectangular aeration tank having the same volume of aeration type aeration.

Further, since the surface aeration device does not require a high-pressure blower or a diffuser, there is no occurrence of a decrease in wind pressure due to aging of the high-pressure blower and a lack of oxygen in the aeration tank due to clogging of the diffuser. In addition, a stable purification treatment function is always exhibited, and further, these maintenances become unnecessary, and the maintenance and management of the sewage purification treatment device becomes easy.

The present invention combines the above-mentioned batch type, oxidized ditch type aeration tank, and photosynthetic bacteria to stably purify high-concentration organic wastewater such as livestock sewage with activated sludge, and to color the treated water. It is possible to provide a sewage treatment method and a sewage treatment apparatus which prevent the remaining sewage treatment apparatus and which requires little management of the sewage treatment apparatus and which has a low running cost.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart of a wastewater treatment process showing one embodiment of the present invention, and FIG. 2 is a schematic plan view of a wastewater treatment device showing one embodiment of the present invention.

An apparatus for treating high-concentration organic sewage according to an embodiment of the present invention is an apparatus for culturing photosynthetic bacteria 17 and an oxidizing groove type aeration tank 1 in which sewage 11 is charged and treated water 10 is discharged in a batchwise manner. Tank 2 for adding photosynthetic bacteria to aeration tank 1
It is provided with.

The aeration tank 1 has a depth of about 2.5 m and a width of about 3 m.
The amount of sewage storage is about 200 m ^{3 in} an elliptical oxidation groove type aeration tank, which is also used as a settling tank in batch mode. The photosynthetic bacteria culturing tank 2 is provided so as to be exposed to light, and the photosynthetic bacteria 17 are self-cultured in the sewage 11a and the treated water 10a. Thus, photosynthetic bacteria 17 suitable for each processing facility can be obtained.

The high-concentration organic wastewater will be described below by taking wastewater from a piggery as an example. Sewage 1 from pig house 6
1 is temporarily stored in the sewage pit 7 to be pumped up by a pump. The retention time of the sewage 11 in the sewage pit 7 is desirably about 10 minutes because if the sewage pit 7 is retained for a long time, solids accumulate below the sewage pit 7 and the pump for pumping the sewage 11 becomes clogged. The pumped sewage 11 is separated into a liquid component and sieved solids 15 by passing through a vibrating sieve 9. The sewage 11 a from which the sieved solids 15 have been removed is stored in the charging tank 4. One day's worth of sewage 11a is stored in the charging tank 4. BOD of sewage 11a here
The concentration depends on conditions such as the number of pigs and the season.
It is about 10,000 ppm.

The accumulated sewage 11a for one day is supplied to the charging tank 4
And pumped into the oxidation groove type aeration tank 1. When the introduction of the wastewater 11a is completed, the photosynthetic bacteria 17 that have been self-cultured are added from the photosynthetic bacteria culture tank 2 to the aeration tank 1. The amount of the photosynthetic bacterium 17 added is sewage 11a, 1
m ³ is about 1000mg about per.

Subsequently, the dilution water 16 is supplied from the dilution water tank 3 until the water level in the aeration tank 1 reaches a predetermined water level. The predetermined water level is about 2 m in depth of the aeration tank 1. Dilution water 16
Is automatically turned off by the water level control switch. The amount of sewage 11a from the pig house 6 varies depending on the season and the number of pigs. Therefore, the BOD concentration of the sewage 11 varies depending on the season and day, but the dilution water 16 is supplied to supply the water level in the aeration tank 1. This constant change can be absorbed by constantly keeping the wastewater 11a at a BOD concentration at which the activated sludge-constituting bacteria become active. That is, when the BOD concentration is high, the amount of the sewage 11a is small. Therefore, a large amount of the diluting water 16 is required to keep the aeration tank 1 at a constant water level. Conversely, when the BOD concentration is low, the amount of the sewage 11a is large. The amount of the dilution water 16 is reduced. The concentration of the wastewater 11a can be controlled by such a simple method. The concentration of the diluted sewage 11b diluted with the dilution water is approximately 1500 ppm or less. Note that the photosynthetic bacteria 17 may be added to the diluted sewage 11b diluted with the dilution water 16.

The surface of the aeration tank 1 is aerated by an aerator 18, the flow is regulated by a flow straightening plate 19 in the aeration tank 1, and a water flow occurs in the arrow X direction. The flow in the direction of the arrow X is smaller than the flow in the vertical direction of the rectangular aeration tank in that the flow does not stop even if the aerator 18 is stopped. It is a thing. Aeration is performed for 21 hours, and the contaminants in the diluted sewage 11b are decomposed by the activated sludge constituting bacteria and photosynthetic bacteria.

After the completion of the aeration, the aeration tank 1 is allowed to stand still for about one hour to precipitate the activated sludge and the photosynthetic bacteria 17, and the supernatant 20 which is about one third of the depth of the aeration tank 1 is disinfected by a pump. After being transferred to the tank 5 and sterilized with chlorine or the like, it is discharged as treated water 10. If there is any concern about the quality of the treated water 10, the diluted water 16a may be mixed and discharged in a 0.5-fold amount.

Excess activated sludge 13 generated in aeration tank 1
Is transferred to the sludge filter bed 8 when it is necessary to remove the sludge, where the excess water is removed. I do. The extraction of the surplus activated sludge 13 is preferably performed about once a month, depending on the scale of the apparatus and the degree of sewage.

It is preferable that all operation operations required for daily operation of the present sewage treatment apparatus be fully automatic operation using a control box.

[Brief description of the drawings]

FIG. 1 is a flowchart of a wastewater treatment process according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a sewage treatment apparatus showing an embodiment of the present invention.

FIG. 3 is a general flowchart of the activated sludge method.

[Description of Signs] 1 Oxidation groove type aeration tank 2 Photosynthetic bacteria culture tank 3 Dilution water tank 10 Treated water 11 High-concentration organic wastewater 16 Dilution water 17 Photosynthetic bacteria

Claims (4)

[Claims] Claims 1. A high-concentration organic wastewater is charged into a batch-type oxidation ditch-type aeration tank, photosynthetic bacteria are added to the wastewater, and the wastewater is purified by activated sludge. A method for treating sewage, characterized by discharging. 2. The treatment method according to claim 1, wherein the sewage is diluted to a concentration at which the activity of bacteria constituting the activated sludge is increased. 3. An apparatus for treating high-concentration organic sewage using activated sludge, comprising: an oxidizing groove type aeration tank for batchwise charging and discharging the wastewater; and an aeration tank for culturing photosynthetic bacteria. And a photosynthetic bacterium culture tank to be added to the processing device. 4. The processing apparatus according to claim 3, further comprising a dilution water tank for supplying dilution water to the aeration tank.