JPH0394898A - Treatment of oil-containing waste water - Google Patents

Abstract

PURPOSE:To obtain the method for treating oil-contg. waste water which simplifies stages and operations, improves a treating effect and attains the saving of energy by directly treating the oil-contg. waste water with aerobic lipid metabolizing bacteria which have a high lipid metabolizing power and allow easy handling. CONSTITUTION:The aerobic lipid metabolizing bacteria are inoculated in the oil-contg. medium and are cultured in a large amt. in accordance with the conventional method under aerobic conditions. The resulted premedium is introduced into a culture treating tank A in which water is previously filled. The oil-contg. waste water A is thereafter introduced into the tank and is mixed with the liquid. This liquid mixture is circulated in the tank under the aerobic conditions, i.e., under the supply of a large volume of air (oxygen) to bring the bacteria and the fats and oils into sufficient contact with each other, by which the bacteria are cultured and the lipid in the waste water is decomposed and metabolized. The culture treated liquid obtd. by treating the oil- contg. waste water in the culture treating tank A is put into the aeration tank A and is treated by activated sludge under the aerobic conditions and is thereafter separated to the treated water T and the sludge S in a settling tank A. The sludge S is circulated from the settling tank A to the aeration tank A and is reutilized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the meat shop F! ! place, cafeteria, seafood processing factory, kitchen,
Wastewater containing animal and vegetable oils and fats discharged from combined septic tanks, oil refineries, hair washing factories, leather l'K factories, etc. (7) Concerning biological treatment method J.

(Conventional pinching technique) Conventionally, the most common treatment method for organic wastewater containing animal and vegetable oils and fats (hereinafter referred to as oil-containing wastewater) has been to separate most of the oils and fats using natural flotation (oil bits) or pressurized flotation equipment. After doing that,
Activated sludge method, water sprinkling method, bed method,
This method uses biological treatment methods such as sludge digestion.

However, with conventional treatment methods, separated oils and fats are incinerated, dumped,
In addition to the need for final disposal by landfilling, etc., the conventional biological treatment method described above has a low lipid assimilation ability of the bacteria contained in the sludge7 and the floating of fats and oils causes the sludge to become contaminated with bacteria. Because there was insufficient contact with the plants, sufficient assimilation effects could not be obtained. On the other hand, there is a method in which oil-containing wastewater is directly treated with lipid-assimilating bacteria, Kouhei Bacteria (for example, Japanese Patent Publication No. 51-4. 3 3 1.
1, No. 53-16226) and a method of direct treatment using a chemical reaction (for example, JP-A-57-1.97087) is also known. These treatment methods have the advantage of simplifying the process because they do not require an oil and fat separation step, but the former method has difficulties in handling bacteria and lipid assimilation ability, and requires light energy (electricity). In addition, the latter method requires complicated operations such as pH adjustment, and the treatment effect cannot be sufficiently obtained.

[Problem to be solved by the invention]

The purpose of this invention is to eliminate the above-mentioned drawbacks of the conventional technology, and to simplify processes and operations by directly treating oil-containing wastewater with aerobic lipid-assimilating bacteria that have high lipid-assimilating ability and are easy to handle. The object of the present invention is to provide a method for treating oil-containing wastewater that is simplified, has improved treatment effects, and achieves energy savings. [Means for solving the problem] The purpose is to assimilate lipids in wastewater by culturing aerobic lipid-assimilating bacteria under aerobic conditions in a culture treatment tank containing oil-containing wastewater. This can be achieved using a unique oil-containing wastewater treatment method. An overview of the method of the present invention will be explained with reference to Figure 1. First, aerobic lipid-assimilating bacteria collected (separated from miscellaneous bacteria) by the method described below are inoculated into an oil-containing medium, and then cultured in large quantities under aerobic conditions according to a conventional method.

After introducing the obtained preculture solution into culture treatment tank A filled with water in advance, oil-containing wastewater A is introduced and mixed, and this mixed solution is heated under aerobic conditions, that is, under the supply of a large amount of air (oxygen). The bacteria are cultured by circulating the waste water in the tank to bring the bacteria into sufficient contact with the oil and fat, thereby decomposing and disassimilating the lipids in the wastewater. The amount of pre-culture solution is generally 1.0% of the culture treatment tank capacity.
/100~I. / l O is appropriate.
It is preferable to introduce wastewater in batch mode at first, then gradually increase the amount introduced as the number of bacteria increases, and finally in continuous mode. The culture treatment tank becomes high temperature due to heat generated by biological reactions, so as shown in Figure 1, the liquid in the tank is introduced into a heat exchanger, cooled, and then returned to the tank again. It is necessary to cool and maintain the temperature (usually about 30-45°C). It should be noted that oil-containing wastewater can be used with either high or low lipid concentration, and generally a concentration of about 50 to 5,000 mg/Q is used. Also, does oil-containing wastewater support the growth of microorganisms?
Basically, according to the usual method, the BOD:N:P ratio is 100.
:521, if necessary in advance (N!■■)2
Adjust with CO and/or K2HPO4.

The culture solution obtained as described above can be disposed of as is if the residual lipid content and other organic substances meet environmental standards, but especially when using highly concentrated oil-containing wastewater, it is necessary to further increase the assimilation treatment effect. Subsequently, it is preferable to subject the culture-treated solution to a conventional aerobic biological treatment such as activated sludge treatment or watering hearth treatment. For example, in the case of activated sludge treatment, as shown in Figure 1, the culture solution obtained by completely treating oil-containing wastewater in culture treatment tank A is put into aeration tank A and treated with activated sludge under aerobic conditions. The treated water T and sludge S are separated in a settling tank A. The sludge S is circulated from the settling tank A to the aeration tank A and reused.

In addition, in the present invention, in order to effectively utilize the aerobic lipid-assimilating bacteria contained in the culture treatment solution, at least a portion of the culture treatment solution is added to other oil-containing wastewater B, and this Aerobic biological treatment can be applied. However, the other oil-containing waste water B used in the process is preferably one with a low lipid concentration of 200 μ/Q or less. When the activated sludge treatment method is used as a normal aerobic biological treatment method, as shown in Figure 1, at least a part of the culture treated liquid core from the culture treatment tank A and oil-containing wastewater B are transferred to the aeration tank ■3. After treatment with activated sludge under aerobic conditions as described above, the treated water T and sludge S are separated in the sedimentation tank [3]. tt According to the Okono Yoyo treatment method, it is possible to omit the usual pre-treatment of oil-containing wastewater, such as oil cleaning 1. and a pressurized flotation device. The culture treatment tank used in the present invention may be one that can cultivate aerobic lipid-assimilating bacteria in oil-containing wastewater under aerobic conditions. However, in a culture treatment tank that does not have a liquid circulation mechanism like a conventional jar fermenter, during operation, lipids tend to become liquid or lumps and float to the surface, which prevents sufficient contact between lipids and bacteria. As a result, the culture of bacteria becomes insufficient and a high assimilation treatment effect cannot be expected.

Therefore, in the present invention, it is preferable to use a culture treatment tank equipped with a liquid circulation mechanism as shown in FIGS. 2 and 3.

Culture treatment tank A shown in FIG. 2 is composed of an outer tank 2a and an inner tank 3a, and the inner tank 3a is fixed and placed above the outer tank with a support 4. A liquid circulation line L2 extending to the bottom of the outer tank 2a is connected to the bottom of the inner tank 3a, and a pump 5 for circulating a mixed liquid of preculture liquid and oil-containing wastewater is connected to the line L2. An air pump 6 for supplying air to the liquid is connected to a line L3,
11, I-1 is a wastewater supply line, and L4 is a culture treatment liquid discharge line, which is located above the outer tank 2a and connected to the inner tank 3a.
It is attached at a slightly higher position than the two end faces of the . To explain an example in which the method of the present invention is carried out continuously using the culture treatment tank 1A shown in FIG. Line L2-・Bottom part of outer tank 2a 1i2a upper side→
It is circulated through the upper path of the inner tank 3a. At the same time, air is supplied from the air supply line L3 into the liquid circulation line L2 by the air bomb 6. Fresh oil-containing wastewater is continuously introduced into the bottom of the inner tank 3a from the wastewater supply line L1. The oil-containing wastewater introduced into the inner tank 3a descends at a predetermined speed by the circulation bomb 5 while mixing with the previous mixed liquid, and enters the liquid circulation line L2, and is further mixed with a large amount of air supplied from the air supply line L3. It is discharged to the bottom of the outer tank 2a.

During this time, the aerobic lipid-assimilating bacteria in the mixture are in contact with the lipids under aerobic conditions, and are therefore cultured to decompose and assimilate the lipids. Further, the discharged new mixed liquid rises in the outer tank 2a while being continuously subjected to the culture treatment, and most of it overflows into the inner tank from the upper end surface of the inner tank 3a, and enters the line L2 again to repeat the circulation. On the other hand, only the amount of newly supplied oil-containing wastewater is used as a culture solution in the culture solution discharge line L.
4 to the outside of the outer tank 2a.

In both continuous and batch systems, in order to introduce all the lipids supplied into the inner tank 3a into the liquid circulation line L2, the lowering speed of the inner tank 3a at night must be approximately 0.5 m/sec.
It was found that it was necessary to control the temperature more than c.

The first characteristic of the culture treatment tank 1A in FIG.
The aerobic lipid-assimilating bacteria and air already existing in this line V1 are sufficiently stirred and mixed at 9 by the circulation bomb, and are thus discharged to the bottom of the outer tank 2 while being affected by the bacteria. Is Rukoto.

The second feature is that the unutilized lipid discharged to the bottom of the outer tank 2a rises while being similarly affected by aerobic lipid assimilation, and flows from the periphery to the center on the upper surface of the outer tank 2a. Inner tank 3a
Since the microorganism overflows and circulates within the microorganism, it is constantly exposed to the action of the bacteria during operation.

The culture treatment tank 1B shown in FIG. 3 is shown in FIG. Convert A's inner tank 2a to draft 1, Q'+I, and t.
5 things. That is, the culture treatment tank 1B in FIG. 3 is the outer tank 2.
This tube 3b extends from the upper part of the outer tank 2b to near the bottom, and is loaded and fixed on a support stand 7. Also draft tube 3
A submersible mixer 8 is placed above the space b, and a diffuser 9 is placed directly below it. The underwater mixer 8 is a device for lowering the liquid introduced into the draft tube 3b at a predetermined speed, and the diffuser 9 is a device for supplying air to the liquid. Note that IO is a screw blade attached to the mixer 8, 12 is a narrow chamber, L5 is a liquid (preculture solution, oil-containing waste water, etc.) supply line, and L6 is an air supply line. The width (diameter) of the narrowed portion 12 may be determined according to the diameter of the screw blade 10 so that the screw blade 10 can function as a pump to efficiently circulate the liquid in the tube 3b. The narrowed part 12 can be omitted by increasing the diameter of the narrowed part 12 to the diameter of the tube 3b itself, and increasing the diameter of the screw blade 10 accordingly.
To explain the culture processing method using the culture processing tank shown in Fig. 3 using a batch type example, first fill the culture processing tank IB with water through the flattening solution supply line L5, and then add the preculture solution through the same route. The upper part of the draft E tube 3b and the bottom part of the outer tank 21 of the tube 3b]
The water is circulated through the inner bottom part and the upper part of the outer tank 2b.
At the same time, air is supplied from the diffuser 9 to the upper part of the draft soup soup 3b through the air supply line L6. The oil-containing wastewater passes through line L5 to tube 3, similar to the preculture solution.
A certain amount is introduced above b. The oil-containing wastewater introduced into the meat in the tube 3b is mixed with the pre-culture solution and is lowered at a predetermined speed by the submersible mixer 8 together with a large amount of air supplied from the diffuser 9, from the bottom of the tube 3b into the outer tank 2b. It enters the bottom, rises further inside the outer tank 2b, and overflows into the tube 3b again from the upper surface of the outer tank, repeating the cycle. During this time, the aerobic lipid-assimilating bacteria in the mixed solution are in contact with the lipids under aerobic conditions, as in the case of the culture treatment tank shown in FIG. 2, and are therefore cultured to decompose and assimilate the lipids. Note that the rate of descent of the liquid in the tube 3b is also 0.5rn as described above.
/s1 or higher.

The characteristics of the culture treatment tank IB in Figure 3 are also the same as those in the culture treatment tank I in Figure 2.
Similar to case A, the oil-containing wastewater supplied into the second tube 3b is lowered and circulated at a predetermined speed by the submersible mixer 8, so that all the lipids in the wastewater have already been removed by the submersible mixer 8 located above the tube. It is thoroughly stirred and mixed with the supplied aerobic lipid-assimilating bacteria and air, and thus during circulation,
It is constantly exposed to the action of the bacteria mentioned above. The aerobic lipid-assimilating bacteria used in the present one-chicken method are oil-containing wastewater (or sludge) discharged from slaughterhouses, cafeterias, seafood processing plants, flour bunches, combined septic tanks, oil refineries, hair washing plants, leather factories, etc. ). In reality, aerobic lipid-utilizing bacteria are included in these wastewaters along with other bacteria, so in order to collect aerobic lipid-utilizing bacteria, it is necessary to selectively isolate and culture these aerobic bacteria from among the various bacteria. be. An example of this separation method is as follows. Isolation method for aerobic lipid-utilizing bacteria: l) Add an appropriate amount of wastewater to the following isolation medium containing olive oil as the only carbon source, and culture with shaking at 30°C for 17 hours to isolate aerobic lipid-utilizing bacteria. Enrich culture.

2) After diluting the culture solution appropriately, culture it on a plate separation medium containing 1.5% agar to obtain a single colony.

3) Purely isolate aerobic lipid-assimilating bacteria using the following LB plate medium.

4) Confirm the lipid assimilation ability of the isolated bacteria using the isolation medium. Separation medium (in 1Q tap water): (NHJ)2SO4 K2HPO4 KH2PO, Mg So4.7H20 CaC Q2 =6H20 FeSO, -7H20 Yeast extract 2.0 g o. 9g 0.6g O,2g O,075g O,02g O,1g Olive oil 10.08 (pH adjusted to HC)
(adjusted to 7.0 with Q or NaOH) LB plate medium (in tap water IQ): Boli K Buton Bog yeast extract 5g NaC Q 5g cold
Ten 15g (pH adjusted to HC)
Q. (or adjusted to 7.0 with NaOH) For comparison, an example of a conventionally used isolation method for photosynthetic lipid-assimilating bacteria is shown.

Isolation method for photosynthetic lipid-assimilating bacteria: 1) Add an appropriate amount of wastewater to the same isolation medium as above,
Culture at 0°C for 40 hours under anaerobic light conditions (sealed with liquid paraffin) to enrich the photosynthetic lipid-assimilating bacteria. 2) After diluting the culture solution appropriately, culture in the following G5 plate medium containing 1.5% agar under anaerobic light conditions. 3) Purely culture the grown photosynthetic lipid-assimilating bacteria, and confirm the lipid-assimilating ability using the above-mentioned isolation medium.

G5 plate medium (in tap water Q): Polybeptone 5G Yeast extract 58 D,L-Na malate 3.5gD,
L-glutamate Na 4gKH,,PO
40, 12 g κ2HPO4, 0. 1
8 g (p}l adjusted to 7.0 with l{CQ or NaOH) There were 5 strains of aerobic lipid-assimilating bacteria and 4 strains of photosynthetic lipid-assimilating bacteria isolated as described above. Next, in order to investigate the lipid assimilation ability of these bacteria, we added 5QOOmg/Q of olive oil to an artificial wastewater base containing polybebutone as a protein to create an artificial oil-containing wastewater that was similar to the actual one, and added each of the above bacteria to this. is added to obtain O. which indicates the amount of bacterial growth. D, 660 (a method to determine the growth amount by measuring the amount of turbidity caused by the bacterial strain using absorbance at a wavelength of 660 mμ; for details, see "Experimental Agricultural Chemistry", Vol. 1, p. 212, published by Asakura Shoten on 4Jl 36, 1960). , a blank (see Human Studies, Vol. 1, p. 212) was measured and compared with a blank (artificial wastewater base).

Artificial wastewater base (in tap water IQ)': Polybeptone 2.5g (Ni{n)2 SO42. 5 gK,28PO4
2.5 g (pH adjusted to 7.0 with HCflI or Na041) The results are shown in Table 1.

(Leaving space below) Table 1 From the results shown in Table 1, it can be seen that all aerobic bacteria used in the present invention have significantly superior lipid assimilation performance compared to photosynthetic bacteria. This trend was similar to Chihoji for other fats such as beef tallow, lard, and kitchen waste oil. On the other hand, the above 5
The ability of the aerobic bacteria of the species to assimilate various lipids was as shown in Table-2. In addition, in this test, 1 d of the solution obtained by pre-cultivating each bacteria in the above-mentioned isolation medium was mixed with 4 ml containing each lipid shown in Table 2.
Artificial oil-containing wastewater of seeds (each oil and fat was added in the indicated amount to 100% of the artificial wastewater) and 100% of pig viscera washing wastewater (wastewater discharged from a slaughterhouse). Each was added and cultured with shaking at 30°C for 24 hours.

(Left below) As is clear from the results in Table 2, sample NQA-1, A-2 and A-3 strains are particularly concerned about their ability to assimilate various lipids. The identification was carried out by BERGEY'S MAN.
UAL OF SYSTEMATIC BACTERIO
I followed LOGY VoL2. The results are shown in Table-3.

(Left space below) As shown in Table-3, 1 A-4, A-2. and A-13 were aerobic Durum-positive short rods, and because they produced spores, they were identified as belonging to the genus Bacillus. Furthermore, we compared the species of the genus Bacillus described by Burge.

The results are shown in Table 4, and as can be seen from this table,
None of these aerobic strains matched the characteristics of the species described by Bergier.

〔Example〕

Next, the method of the present invention will be explained in more detail with reference to an example in which the above-mentioned aerobic lipid-assimilating bacteria were used.8Example 1 is a batch type example, and Example 2 is a continuous type example. It is. In any of the examples, the second culture treatment tank is
I used the one shown in the figure. However, the catch processing liquid discharge line was set 1 cm higher than the upper end surface of the inner tank. In Example 1, 1) When oil-containing wastewater is treated only in the culture treatment tank (Example), 2
) When the culture treatment solution discharged from the culture treatment tank in l) above is further treated by the activated sludge method at a slaughterhouse (Example),
3) The culture solution was centrifuged to remove aerobic lipid-assimilating bacteria, and this was further treated by Shokuhin Center's activated sludge method (comparative example), and 4) the oil-containing solution used in l) above. A case (comparative example) in which wastewater is directly treated using the activated mud method at a slaughterhouse was explained. FIG. 4 shows its outline.

Example 1 A preculture solution (2) containing aerobic lipid-assimilating bacteria was prepared by culturing A-13 strain on the above-mentioned isolation medium 1 at 30° C. for 17 hours with shaking. Oil-containing wastewater ■ is wastewater from washing pig internal organs in hot water discharged from a slaughterhouse, and the BOD:PXN ratio of the liquid is 100:
(NH2)2Co and K21{E' so that the ratio is 5:1
O. I fixed it. The size of the culture treatment tank is as follows.

Outer tank: Volume approximately 5Q (inner diameter approximately 10aa, height 65 Cl)
l1) Inner tank: Volume approximately 200m Q (Inner diameter 4cm,
(Height: 16 cm) First, preculture solution (0.5Q) and oil-containing wastewater (2) 4.5Q are placed in the culture treatment tank IA in a conventional manner, and these are circulated by the liquid circulation pump 5 at a flow rate of approximately 402/min. At the same time, air was supplied from the air supply line L3 into the liquid circulation line L2 at a flow rate of about 200 mQ/min, and culture processing was performed for 2.4 hours. This is called processing system l. The liquid temperature was maintained at about 30°C by a heat exchanger (not shown). The descending speed of the liquid in the inner tank 3a at this time was 0.5 m/sec.

Next, the aeration tank 13a, l. 3b and 13e, the following activated sludge method treatment was performed. Each aeration tank consists of a transparent container made of acrylic resin with a capacity of 3Q, and air is pumped into the bottom at a rate of 100mQ by an air pump (not shown).
It is equipped with a means (called an air stone) 14 for supplying air at a flow rate of /min. ．． The aeration tank 13a contains oil-containing wastewater ■1
, 012 and activated sludge from slaughterhouse ■I. ．． OQ was added and aeration was performed at approximately 30°C for 24 hours. Processing system for this
Suppose that As the activated sludge (■), a shrinkage surplus sludge from a slaughterhouse (MLSS9840■/Q) was used. aeration fil
3b contains the culture treatment solution from treatment system I. OQ and the above activated sludge I, (112) were added and aerated at about 30°C for 24 hours. This was designated as treatment system (2).

In addition, the aeration tank +3e contains the culture treatment solution ■3 from the treatment system I.
, OQ was centrifuged at 12.00 Orpm for 10 minutes to remove bacteria and the resulting supernatant liquid ■1. OQ and the activated sludge (1,012) were added and aerated at 30°C for 24 hours. This is called processing system (■).

The appearance of the mixed liquids of the treatment systems ①, ②, and ② subjected to the above treatment was approximately as shown in FIG. 4 after being allowed to stand for 30 minutes. That is, in treatment system Ⅰ, lipids adhere to activated sludge and sludge S floats to the surface, in treatment system ③, sludge S settles normally, and in treatment system 1v, sludge S settles but expands. It was a state. Regarding treatment system n, it was determined that the treatment liquid and sludge could not be separated, and the hexane extracted substance was quantified using the entire amount (◎ liquid). For processing systems ■ and ■, the total amount is 12. Centrifugation was carried out at 00 rpm for 10 minutes, and the sludge division (■, ■, respectively) and the treated liquid division (■, respectively) were separated.
, ■) was obtained. For each of the treated liquids and sludge categories described above, quantification of octoxane extracted substances and BOD analysis were performed. The results are shown in Table-5.

Based on the results shown in Table 5, the assimilation rate of IJ in the valley treatment system was investigated. After 24 hours of treatment, the results are shown in Table 6. (Left below) From the results shown in Table 6, the lipid assimilation rate of treatment system I is +08
01Ilg/Q/day, which is clearly very superior compared to other treatment systems. In treatment system ■, which is an activated sludge method in a slaughterhouse that does not use aerobic lipid-assimilating bacteria, the lipid assimilation rate is very slow at 4 tny,/Q/day, and as mentioned above, lipids adhere to activated sludge. This indicates that activated sludge treatment is not possible because the sludge floats to the surface. In the treatment system ■, in which the culture solution containing aerobic lipid-assimilating bacteria and non-assimilated bacteria was treated with activated sludge, the lipid assimilation rate was 132 mg/Q/IE
The treatment system ■ is obtained by removing the lipid-assimilating bacteria from the treatment system ■.
The lipid assimilation rate was approximately 4 times faster than that of 36 mg/Q/day. From the above results, we found that culture treatment using aerobic lipid-assimilating bacteria can assimilate lipids very efficiently, and that by treating the culture solution with activated sludge, the lipid assimilation ability of activated sludge can be improved. As shown in Table 5, both the hexane extract and BOD in the treated water (liquid ■) can be treated to low concentrations. Next, what should be done when oil-containing wastewater is treated continuously? About C
explain. FIG. 5 shows its outline.

Example 2 In FIG. 5, reference numeral 15 denotes an oil-containing wastewater storage tank consisting of a constant temperature bath equipped with a stirrer 16. The lipids in the +73'S oil wastewater in this storage barrel are emulsified by ultrasonic oscillation 11117 (18 is an oscillator) to prevent floating. The oil-containing wastewater used was of two types: pig visceral washing wastewater used in the batch process (hereinafter referred to as oil-containing wastewater I) and low-concentration cafeteria wastewater (hereinafter referred to as oil-containing wastewater ■), both of which had a BOD: N: P of 100. :5:1 (NH2)2CO and K2
Adjusted with HPO4.

The culture treatment tank was the same as in Example 1. In the treatment system for oil-containing wastewater I, the liquid temperature in the storage tank 15 is set to 45°C, and the inner tank 3a of the culture treatment tank IA (container 5Q) is transferred by the wastewater transfer bomb 19.
(volume 200 d) was transferred and introduced oil-containing wastewater I at a flow rate of 5 OQ/day. On the other hand, air is supplied to the liquid circulation line L2 in the Aoi treatment tank IA at a flow rate of 200 d/min by an air pump 6, and the liquid in this tank is circulated by a liquid circulation bomb 5 at a flow rate of 40 Q/min. Ta. Inner tank 3 at this time
The descending speed of the liquid in a was 0.5 m/sec.

The culture treatment liquid discharged from the culture treatment tank IA is stirred by a stirrer 20.
After receiving the culture treatment liquid Bisol 1-21 (volume (1,5Q)), it is transferred to the aeration tank 13 (volume 3Q) by the culture treatment liquid transfer bomb 22 at a flow rate of 3,0Q/day, and the excess The culture solution was received and stored in the culture solution storage tank 23 (volume 20Q).The aeration tank 13 was previously filled with activated sludge from a slaughterhouse at a volume of 3.0Q/.

Aeration in the aeration tank 13 is performed using the air pump 24 of the air stone l4! This was done by introducing into the bottom of the tank at a flow rate of 00 d/min. The treated liquid discharged from the aeration tank 13 was transferred to the sedimentation tank 25 (volume 1.0Q), where it was separated into solid and liquid to obtain the final treated liquid and sludge. This sludge is transferred to the aeration tank 13 by the sludge transfer bomb 26 for 3.0Ql.
It is returned and circulated at the daily flow rate. On the other hand, in the treatment system for oil-containing wastewater H, the liquid temperature in storage tank 15 is
℃, and directly transfer the oil-containing wastewater from the wastewater transfer pump 19.
At the same time, the culture treatment liquid obtained by treating the oil-containing wastewater 1 in culture treatment tank A is transferred into the aeration tank 13 at a flow rate of 5,000 Q/IE.
The same treatment as in the case of oil-containing wastewater I was carried out. The average values for one week of the treatment results on jfi are shown in Table-7. 78
50mg#l to 266mg/Q. and 27
BOD 18.3mg/Q
It can be seen that continuous treatment is possible until it can be discharged into rivers. Especially in the culture treatment system, the BOD load is 7.85 kg BOD/+Mura/D and the normal 1-2 kg BOD/rr? The fact that it can be processed with a much higher load compared to /D is that the culture treatment tank with a circulation system as shown in Figure 2 has a high air (oxygen) supply capacity and a mixing system that allows sufficient contact between lipids and lipid-utilizing bacteria. Demonstrates superior ability. In addition, the BOD removal rate in the culture treatment system was slightly worse at 65.5% compared to the lipid removal rate of 75.9%, but by performing two-stage treatment with activated sludge, which has excellent BOD removal ability, , which ultimately indicates that the BOD processing was sufficiently performed.

Next, we will look at the treatment results for oil-containing wastewater (■). Since this wastewater has a relatively low concentration for an oil-containing wastewater, we used a culture-treated solution containing aerobic lipid-assimilating bacteria obtained from a completely different system in an amount of 1% of the wastewater. Good results were obtained even though the treatment was carried out only by adding it. i.e. lipid before treatment 165 ILlg/L
BOD 738mg/f1 after processing lipid 1.5mg
/L BOD 11.6mg/D. The level has reached a level where it is possible to discharge water into rivers. This result shows that for low-concentration oil-containing wastewater, such as cafeteria wastewater, activated sludge treatment is possible without conventional pre-treatments such as oil extraction or coagulation flotation by adding a small amount of aerobic lipid-assimilating bacteria to the aeration tank. It shows.

[Function and effect of the invention]

The method of the present invention directly treats oil-containing wastewater with aerobic lipid-assimilating bacteria that have a high lipid-assimilating ability and are easy to handle, so it simplifies the process and operation, prevents the assimilation treatment effect, and saves money. It is possible to achieve five-energy conversion.

This treatment effect can be avoided by further applying conventional aerobic biological treatment to the culture solution after oil-containing wastewater treatment. In addition, by introducing at least a portion of the culture-treated liquid into another low concentration oil-containing wastewater and performing a normal aerobic biological treatment, the wastewater can be further processed compared to a simple normal biological treatment. It is possible to effectively carry out the assimilation process 4'' and also to perform oil biting, thereby omitting preliminary treatment using a pressurized flotation device or the like.

Furthermore, by carrying out the method of the present invention using a culture treatment tank with a circulation system as shown in Figs. 2 and 3, it is possible to further improve the effectiveness of the assimilation treatment of Naruyu wastewater compared to the conventional culture treatment tank. can.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of the method of the present invention, FIGS. 2 and 3 are schematic diagrams of an example of a culture treatment tank used in the method of the present invention, and FIGS. It is an explanatory diagram of a batch processing method and a continuous processing method. IA...Culture treatment tank 1B consisting of outer pi'2a and inner tank 3a...Culture treatment tank 4 consisting of outer tank 2b and draft tube 3b...Support 5...Liquid circulation pump 6...・Dish Arbonp 7...Support stand 8...
- Submersible mixer 9 with screw blade 10...Diff user 12...Narrow chamber portion 13, 13a,
13b, 13e-Aeration tank 1 4-:n Earth tone l5...Oil-containing wastewater storage tank 16, 20...
・Agitator 17...Ultrasonic oscillator 19 with oscillator 18・
・・Wastewater transfer bomb 21・・Culture treatment liquid bottle meter ・22・・Culture treatment liquid transfer bomb 23・・Culture treatment liquid storage tank 24・・Air bomb 25・・
-Settling tank 26...Sludge transfer pump L1...Wastewater supply line L2...Liquid circulation line L3, L6...Air supply line

Claims (1)

[Scope of Claims] 1. The method is characterized in that lipids in wastewater are assimilated by culturing aerobic lipid-assimilating bacteria under aerobic conditions in a culture treatment tank containing wastewater containing animal and vegetable oils and fats. A method for treating oil-containing wastewater. 2. The method according to claim 1, wherein the culture solution discharged from the culture treatment tank is further subjected to a conventional aerobic biological treatment. 3. Add at least a portion of the culture treatment liquid discharged from the culture treatment tank to other wastewater containing animal and vegetable oils and fats, and subject it to normal aerobic biological treatment to assimilate the lipids in the other wastewater. 2. The method of claim 1. 4. The culture treatment tank consists of an outer tank and an inner tank installed above the outer tank, and the bottom of the inner tank has a liquid circulation line that extends to near the bottom of the outer tank. 4. The method according to claim 1, wherein a pump for lowering and circulating the liquid in the inner tank at a predetermined speed is connected to a line for supplying air to the liquid in the line. 5. The culture treatment tank consists of an outer tank and a draft tube extending from the upper part of the outer tank to near the bottom, and above the tube there is an underwater mixer and the mixer for lowering the liquid introduced into the tube. 4. The method according to claim 1, wherein a diffuser for supplying air to the liquid is arranged directly below the liquid. 6. Bacillus as an aerobic lipid-assimilating bacterium
6. The method according to claim 1, wherein a strain belonging to the genus s) is used.