JPS5910399A - Biological treatment of waste water containing organic material - Google Patents

Abstract

PURPOSE:To treat efficiently waste water contg. org. material by subjecting the waste water to aeration and agitation suited for propagation of anaerobic bacteria in an anaeration tank, drawing out part of the waste and subjecting the same to control of a C/N ratio, etc. then returning the water to the anaeration tank. CONSTITUTION:Waste water is collected in a control tank 1 to control pH, etc., and is fed into an anaeration tank 2. The water is lightly aerated by the air fed from a fan 5 in the tank 2 to propagate faculative anaerobic bacteria. The waste water in the anaeration tank wherein the anerobic bacteria cont. the facultative anaerobic bacteria live is conducted by a pump 6 into an activation tank 7, where the water is subjected to the control of a C/N ratio and the addition of an inorg. material and is also subjected to the aeration and agitation under the same condition as the condition in the tank 2 by the air fed from the fan 5 for a prescribed time; thereafter the waste water in the tank 7 is returned to the anaeration tank. The capacity of the tank 7 may be about 1/100-1/1,000 of the capacity of the tank 2.

Description

DETAILED DESCRIPTION OF THE INVENTION This issue 8A relates to a method for biologically treating wastewater containing organic substances, such as raw water from fisheries processing, raw wastewater from human and livestock processing, and wastewater from agricultural processing.

As is well known, as a biological treatment method for this type of wastewater, the activated sludge method, which consists of the steps shown in FIG. 1, has been used for a long time. In this method, wastewater is temporarily stored in the adjustment tank A, and as necessary, the liquid quality is made uniform, nutrients are added, and P.
After performing work such as H adjustment, water is continuously supplied to the aeration tank B during a certain period of time.While the wastewater remains in the aeration tank B for a certain period of time, organic substances in the wastewater are removed by the air sent from the blower C. Active aerobic cells! ll' is oxidized and decomposed to form activated sludge (floracne), and the wastewater is sent to the sedimentation separation tank together with this activated sludge.In the sedimentation separation tank Dvc, it is also allowed to stay for a certain period of time to separate the activated sludge and supernatant. The clear liquid is separated and the supernatant liquid is discharged as treated water.On the other hand, a part of the settled activated sludge is returned to the aeration tank B by the sludge pump EK and used for circulation. It maintains the sludge concentration and makes it useful for oxidative decomposition by aerobic bacteria (C).The remaining activated sludge returned to the aeration tank B1, the excess sludge, is pulled out of the 1111 circulation system and sent to the sludge dehydrator I?, etc. The liquid is broken down into 71 bodies.
○ In such activated sludge method, solids must be disposed of by landfill, dumping, etc.1, Wastewater BOI) #
When IW is high at t-1, oxidative decomposition by aerobic bacteria does not progress satisfactorily, so when treating wastewater with a BOD concentration of tW or higher using the activated sludge method, diluted water must be used. In addition to the volume of sound, it is necessary to completely reduce the BOD concentration. As the amount of wastewater due to this diluted water increases, aeration tank B etc. becomes larger and operation management becomes more complicated. This is accompanied by various drawbacks such as an increase in the power cost of the blower C due to the increase in the amount of wastewater.
However, if there is a change in the composition or concentration of wastewater, changes in weather conditions, or other physical and chemical conditions, the survival conditions for bacteria in the treatment system will change accordingly. Another drawback is that smooth wastewater treatment cannot be carried out, and therefore a great deal of effort is required to stabilize the treatment system.

This invention was made in consideration of the above-mentioned (g) circumstances; regardless of the degree of BOD of wastewater, it can be treated extremely efficiently, thereby reducing operating costs, downsizing the equipment,
The purpose is to simplify operation management and ensure the stability of the treatment system to ensure smooth wastewater treatment.

The feature of this invention is that wastewater containing 11M organic substances is sequentially sent from the adjustment tank to the anaerobic tank and then to the coagulation separation device, and in the coagulation separation device, the sludge is coagulated by adding all the flocculant to purify the wastewater. In the method, in the anaerobic tank, aeration and agitation suitable for the growth of anaerobic bacteria including facultative anaerobic bacteria is performed, and a part of the wastewater is separately collected in VC to adjust the C/N ratio; After adding inorganic substances and performing aeration and agitation, the wastewater is returned to the anaerobic tank and the bacteria in the wastewater are activated in steps 1 to 1 to ensure the stability of the wastewater treatment system. I will explain in detail below.

This departure I! In method J, wastewater is purified through an adjustment tank 1, an anaerobic tank 2, a coagulation separation device @3, and, if necessary, a higher treatment step 4.

Some of the anaerobic bacteria that act in this wastewater treatment system are S tr
epLococc4) genus, Bacillus
s) Any anaerobic bacterial group containing icM bacteria such as the genus icM may be used. Such anaerobic bacteria are placed in advance into the anaerobic tank 2 before the operation of the wastewater treatment system starts and allowed to die, and from then on, those that naturally proliferate in this tank 2 are used. 0 Wastewater includes seafood processing wastewater, stocked raw wastewater, agricultural processing wastewater,
Any wastewater containing other organic substances can be treated by the method of this invention, regardless of its type. Works such as oxidation, addition of nutrients, and pH adjustment are performed. Then, after being allowed to stay for a predetermined period of time, a certain amount of water is continuously or all at once supplied to the anaerobic tank 2.

In the anaerobic tank 2KL, all of the waste water supplied from the adjustment tank 1 is retained and aerated and stirred by air sent from the blower 5. This aeration provides a small amount of eζ dissolved oxygen in the wastewater in order to proliferate facultative anaerobic bacteria, which are the main group of anaerobic bacteria living in the wastewater in the anaerobic tank 2, and
Since the purpose is to evenly distribute this dissolved oxygen in the wastewater, experience shows that weak aeration, usually about one-tenth or less of the amount of aeration in the aeration tank in the conventional activated sludge method, is sufficient.

It has been experimentally proven. This is because if a larger amount of aeration is performed, although the wastewater is sufficiently agitated, the living conditions for facultative anaerobic bacteria will be impaired.

By performing aeration suitable for these conditions, facultative anaerobic bacteria introduced before the start of operation of the wastewater treatment system can be removed in the anaerobic tank 2 even though wastewater is continuously supplied and discharged. The microorganisms containing m-type bacteria proliferate and remain inhabited at all times.

The wastewater in the anaerobic tank 2, where anaerobic bacteria including such facultative anaerobic bacteria live, is guided to the activation tank 7 by the pump 6, and the C/N ratio is adjusted and inorganic substances are added. At the same time, aeration and agitation under the same conditions are performed in the anaerobic tank 2 for a predetermined period of time using air sent from the blower 5, and then the wastewater in the activation tank 7 is returned to the anaerobic tank 2. The size of each side of the activation tank 7 may normally be about 1/100 to 1/10 of the total capacity of the 2-capacity anaerobic tank. Further, the C/N ratio is appropriately selected and adjusted within the range of IO to 25 depending on the pollutant components of the wastewater.

This adjustment of the C/N ratio is performed in order to activate the anaerobic bacteria contained in the wastewater and increase their growth rate, but if the C/N ratio is high, nitrogen components such as urea may be added. If the C/N ratio is low, the addition of carbon components such as blackstrap molasses and other additives can reduce the anaerobic bacteria contained in the wastewater, as well as adjusting the C/N ratio. This is done to activate the cells and speed up their proliferation, but it is usually done using active silicic acid 5.
Based on about 0 coefficient, add a solution containing about 50% of other necessary salts to about 1/300 to 10 liters of the capacity of the activation tank 7. The standard time for the wastewater to remain in the activation tank 7 is about 10 times the division time of facultative anaerobic bacteria present in the wastewater, specifically 2 hours and 30 degrees, but depending on the conditions of the wastewater and other conditions. Extend or shorten the residence time as necessary for these reasons. The wastewater in the anaerobic tank 2 is supplied to the activation tank 7 after the predetermined amount described above is supplied all at once and subjected to the above-mentioned treatment, and then the wastewater in the activation tank 7 is again supplied all at once to the anaerobic tank 2. A so-called batch process, in which the waste water is recycled back into the atmosphere, is standard, but if the wastewater composition is not particularly suitable for the growth of anaerobic bacteria, a fixed amount may be fed continuously. As mentioned above, the anaerobic bacteria contained in the wastewater treated in the activation tank 7 have been activated, and the wastewater is in the most suitable state for promoting microbial decomposition of organic matter. By returning the wastewater to the anaerobic tank 2, the wastewater in the anaerobic tank 2 is brought into a state suitable for promoting microbial decomposition of organic matter, similar to the wastewater returned from the activation tank 7, that is, a state in which the anaerobic bacteria in the wastewater are activated. It becomes. Batch treatment of the wastewater in the activation tank 7 may be performed continuously depending on the wastewater composition, but only when there is a possibility that the treatment system will not be able to operate smoothly due to changes in the various conditions of the wastewater. It may be performed continuously. The temperature of the wastewater in the activation tank 7 must be within ±10°C of the temperature of the wastewater in the anaerobic tank 2, but the most desirable temperature is 30°C or more and 32°C or less. It is.

Incidentally, depending on the nature of the waste water or various circumstances, the regulating tank 1 and the anaerobic tank 2 may be combined into one A to form a regulating anaerobic tank that also serves as these two tanks 1 and 2. However, this is included within the technical scope of the method of this invention.

In the flocculation separation device 3, the wastewater in the anaerobic tank 2 and the flocculant are mixed to produce sludge.The flocculant is added during the water supply process immediately before the wastewater is introduced into the flocculation separation device 3. For example, since the waste water is well mixed, operations such as stirring within the coagulation separation device 3 can be omitted. The best flocculant is an effective combination of inorganic and organic flocculants.
Adjust the combination depending on the wastewater conditions. The generated sludge is separated from the liquid part. In the embodiment shown in FIG. 2, this separation is performed using a settling tank, but is not limited to this, and other mechanical, A separation method using physical means can also be included in this coagulation separation device 3. The remaining liquid part, which has been separated from the sludge and the sludge is passed through the sludge dehydrator 8 and the solid part is discharged outside the treatment system, is used as treated water in the treatment system if its pollution concentration is below the regulation value. Although it is discharged outside, the amount exceeds the regulation value.
In this case, the water is treated in a higher-level treatment process 4 such as sand filtration and rotating disks so as to be below the regulation value, and then discharged as treated water to the outside of the treatment system. The sludge components generated in this higher-level treatment step 4 are mixed with wastewater from the adjustment tank 1 and returned to the anaerobic tank 2. In addition, if the water content of the sludge separated from the liquid part in the coagulation separation device 3 is high In this case, the sludge may be passed through a sludge thickening device (not shown) before being applied to the sludge dehydrator 8.Also, the aeration in the anaerobic tank 2 and the activation tank 7 may be carried out by other methods instead of being sent from the blower 5. Of course, aeration may be performed by other means.

As is clear from the above explanation, unlike the conventional activated sludge method, this method adds a coagulant to the wastewater inhabited by facultative anaerobic bacteria in the anaerobic tank 2. As long as sludge (floc) can be generated in the coagulation separation device 3 simply by doing this, the wastewater can be treated regardless of its concentration. Therefore, since there is no need for dilution water to dilute wastewater, it is possible to downsize various devices, simplify operation management, eliminate the need for dilution water supply facilities, etc., and reduce the amount of aeration. It is possible to reduce operating costs because only a small amount is required.0 Furthermore, even if the conditions of wastewater suddenly change and abnormalities occur in the wastewater treatment system, it is possible to reduce the operating cost. By returning the wastewater adjusted in the anaerobic tank 7 to the anaerobic tank 2, the microorganisms contained in the wastewater in the anaerobic tank 2 are brought into an activated state, that is, a state suitable for decomposing organic matter in the wastewater. This makes it possible to stabilize the wastewater treatment system. Therefore, compared to the conventional method, it is possible to greatly reduce the labor required to stabilize the system.Furthermore, when all bacteria belonging to the genus Lactobacillus are placed in facultative anaerobic bacteria, By the action of the bacteria belonging to the genus Lactic Acid Bacteria, it is possible to prevent the generation of bad odors in the wastewater treatment system and the sludge separated by the sludge dehydrator 8.

Examples of the method of this invention will be described below.

Wastewater/Sage. Process wastewater such as sardine thawing water O25 old/day, COD concentration 300 ppm, BOD concentration 900 ppm Anaerobic tank - Air volume by blower is 0-781 Tl" 7 minutes.

The blower required for this air volume is 1.5KW x 1 unit.

The required air volume in the conventional activated sludge method is! )50♂/B
As ODKg, 2sot/day x 0.9Kg x 50rn” ÷ 24 hours ÷ 6
0 min = 7.8r11s/min The blower required for this air volume is I
IKWXI unit 0 flocculation separation equipment - COD at the outlet of this equipment
The concentration is 60ppm.

Since the BOD concentration was 135 ppm, it was subjected to sand filtration as a higher-level treatment step to reduce it to below the regulatory value, and then released as treated water.

In addition, as a flocculant, liquid sulfate band 7.5% solution 10
ppm, medium anionic polymer 0.3 pp+n (r added).

Next, the wastewater from the anaerobic tank is supplied to an activation tank with a capacity of 1/300 of the anaerobic tank capacity, and aerated under the same conditions as the anaerobic tank.
Adjust the CZN ratio to 15, add all of the inorganic solution that meets the above conditions to 1/400 of the capacity of the activation tank, and heat at a temperature of 30°C, which is 7°C higher than the temperature of the anaerobic tank. The wastewater that has been retained in the activation tank for approximately 2 hours and 30 minutes is collected once a day.
As a result, compared to the case without this treatment, the sludge production rate in the flocculation separation device increased by about 20 inches, and the required air flow rate in the anaerobic tank increased by about 10%.
At the same time, the opening time of each tank was shortened by 15 inches.

[Brief explanation of the drawing]

Figure 1 shows a general flow sheet for the conventional activated sludge method. Figure 2 shows a flow sheet for this invention method. ,
7...Activation tank. Patent applicant: Agent for Oshinozu Food Industry Co., Ltd.
Mihiko Watanabe volunteered to write the procedural amendments) 1. Case Description 1982 Patent Application No. 120067 2 Title of Invention Biological Treatment Method for Wastewater Containing Organic Substances 3.1ili
Relationship with the person who corrects the case Patent applicant name: Oshinozu Foods Industry Co., Ltd. 4, Agent: 530 Telephone: Osaka 06 (361) 38
31 Address: 2-21 ill, Tayu-cho, Kita-ku, Osaka City Claims column 6, Contents of amendments Claims (amended) as per the attached sheet 1. Waste water containing organic substances is transferred from the adjustment tank to the anaerobic tank, A biological treatment method for wastewater containing organic substances, in which the wastewater is sequentially sent to a coagulation separation device, and in the coagulation separation device, the sludge is coagulated by adding a coagulant to purify the wastewater, and in the anaerobic tank, , perform aeration and agitation suitable for the growth of anaerobic bacteria, including facultative anaerobic bacteria, and use a part of the wastewater in the anaerobic tank where anaerobic bacteria, including facultative anaerobic bacteria, live in an activation tank. The wastewater in the activation tank is returned to the anaerobic tank after being taken out, the C/N ratio is adjusted and inorganic substances are added, and aeration and agitation 112 under the same conditions at 11mMJ is performed for a predetermined time. Biological treatment method for wastewater containing organic substances. 2. The method for biological treatment of wastewater containing organic substances according to claim 1, wherein the facultative anaerobic IIl bacteria are facultative anaerobic bacteria including bacteria of the genus Lactobacillus.

Claims (1)

[Claims] 1. Sending wastewater containing organic substances from the adjustment tank to the anaerobic tank and to the flocculation separation device, and the flocculation separation device: 'c/I
``i'' is a biological treatment method for wastewater containing organic substances in which sludge is flocculated by adding a flocculant to purify the wastewater, and in the anaerobic 4v, anaerobic bacteria including oily anaerobic bacteria are At the same time, a part of the wastewater in the anaerobic tank where anaerobic bacteria including facultative anaerobic bacteria inhabit is collected into an activation tank to increase C.
Wastewater containing organic substances characterized by adjusting the lN ratio, adding inorganic substances, and opening aeration stirring under the same conditions in the aeration tank at a predetermined time, and then returning the wastewater in the activation tank to the anaerobic tank. biological treatment methods. 2. The facultative anaerobic bacteria are milk 11! Biological treatment method for wastewater containing organic substances as claimed in claim 1, which are oily anaerobic bacteria including bacteria of the genus Fungi.