JPS588318B2 - Treatment method for food manufacturing wastewater, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater generated during food production.

More specifically, the present invention aims to remove suspended solids (
The present invention relates to a method for removing or reducing SS (hereinafter referred to as SS) and BOD.

Generally, food manufacturing wastewater contains large amounts of sugars, proteins, etc.
If the water is released as is, the river will become highly nutrient-rich and polluted.

The present inventors conducted a wide-ranging search for practical microorganisms in order to effectively treat food manufacturing wastewater, and as a result, a large number of polysaccharide-assimilating yeasts were widely identified, and these yeasts were found to be useful in food products. I learned that it is surprisingly effective in treating manufacturing wastewater.

Then, they found that if the food production wastewater thus treated was further treated with activated sludge, COD could be reduced very efficiently, and the present invention was completed.

The present invention is a method of adding one or more types of polysaccharide-assimilating yeast to food manufacturing wastewater to assimilate and consume organic matter, and further, a method of treating this treated wastewater with activated sludge.

The wastewater treatment method of the present invention has a very wide range of applications.

For example, wastewater from the production of alcoholic beverages such as sake, shochu, wine, and beer, wastewater from the production of beverages such as fruit juice and soft drinks, wastewater from the production of yeast, wastewater from the production of bean paste, wastewater from the production of noodles, wastewater from the production of potato starch, fish meat, livestock meat, etc. It is extremely effective for wastewater from food-related manufacturing, such as processed wastewater, tofu manufacturing wastewater, and desizing processing wastewater.

The polysaccharide-assimilating yeast used in the present invention was newly discovered by the present inventors in an extremely wide range, but taxonomically, these yeasts belong to known strains. However, it is completely unknown that these yeasts have the ability to assimilate polysaccharides and purify them by decomposing and assimilating polysaccharides in wastewater.

The polysaccharide-assimilating yeast used in the present invention can be easily isolated and collected by the presence of polysaccharide-assimilating yeast, so it is not limited to a specific bacterial species; Exemplary bacterial strains and their deposit numbers are as follows.

Devariomyces hanzenii D-N
Baryomyces hansenii) No. 359
No. 2 Pihia Acacia AM-37W
chia acaciae) No. 3593 Hansenula anomala Y-1
anomala) No. 3594 Pihia Nakazawa LK
B-335 Pichia nakaza
wae) No. 3595 Pichia Dispora Pd-67
1 Pichia dispora No. 3596 Candida species AS-50 Candida species No. 359
No. 7 Endomycopsis platypodis AM-46 Endomycopsis platypodis
No. 3598 Satsukaromyces cerevisiae Br-1
Saccharomyces cerev
isiae) No. 3972 These isolated yeasts all belong to known species, and the mycological properties of these yeasts are as follows.

Debaryomyces hanzenii DN wort medium (cultured at 25°C for 2 days): Cells are spherical and short oval.

Produces a skin ring and sediment. Wort agar medium (17°, 1
Kezuki): Yellowish brown, smooth fungal moss.

Slide medium: No pseudohyphae formation.

Ascospore formation: Usually one spore is formed in the ascus produced by the fusion of two vegetative cells.

One oil droplet in the center of the spore Glucose fermentation: Weak nitrate assimilation: None Vitamin requirement: Yes Growth at 37℃: None Pichia acacia AM-37W Wort medium (25℃, 2 days culture): Cells Spherical, oblong and elongated shapes, producing sediment.

Wort agar medium (17°C, 1 month): Grayish brown, wrinkled fungal moss.

Slide culture: formation of pseudohyphae.

Two to three or many blastospores are branched.

Formation of ascospores; formation of 2 to 4 short-rimmed cap-shaped spores in an ascus produced by the conjugation of two vegetative cells.

Fermentability of sugars: glucose fermentation.

Assimilation: Assimilates nitrate, succinic acid, and citric acid.

Vitamin requirement: Yes Growth at 37°C: Yes Hansenula anomala Y-1 Wort medium (25°C, 3 days culture): Cells form spheres, elliptical and elongated shapes, films, and sediments.

Wort agar (17°C, 1 month): Forms fungal moss, smooth grayish white or dry white, with significant wrinkles.

Slide medium: elongated cells connect and form pseudohyphae.

Blastosphere is spherical, oval. Ascospore: A vegetative cell directly becomes an ascus, forming 1 to 4 cap-shaped spores.

Fermentability of sugars: glucose, sucrose, raffinose (1/3) fermentation.

Galactose and maltose are weak and are not fermented at all. stomach.

Nitrate assimilation: None Vitamin requirement: None Pihia Nakazawae LKB-335 Wort medium (25℃, 3 days culture): Oval, cylindrical,
Thin ring and sediment.

Wort agar medium (17°C, 1 month): Cream-colored, smooth fungal moss.

Slide medium: pseudohyphae, blastospores formation.

Ascospores: Postzygotic ascus formation, 2-4 cap-shaped spores.

Fermentability: Glucose, galactose fermentation.

Nitrate enrichment: None Vitamin requirement: None Growth at 37°C: None Pichia dispora Pd-671 Wort medium (25°C, cultured for 2 days): Cells form spheres, oblong ovals, rings, and sediment. .

Wort agar medium (17°C, 1 month): Cream-colored to brownish smooth, flat fungal moss formed.

Slide culture: No pseudohyphae formation.

Ascospore formation: Ascospore formation by sexual reproduction, rarely by unisexual reproduction.

Usually two spherical or oval spores (with a pair of short edges) form).

Fermentability: Glucose fermentation.

Assimilation ability: Assimilates dl-lactic acid and succinic acid, but does not assimilate nitrate.

Vitamin requirement: Yes Growth at 37℃: Yes Candida Species AS-50 Ascospore formation: none Wort medium (cultured at 25°C for 2 days): Cells are spherical and cylindrical.

Slide medium: pseudohyphal formation.

Endomycopsis plateipodis AM-46 wort (cultured at 25°C for 2 days): In addition to cells, spherical, oval, and elongated shapes, there are also pseudohyphal and true hyphal shapes.

Produces a skin ring and sediment.

Wort agar (17°C, 1 month): Orange-yellow, with prominently raised and reticulated fungal moss.

Slide medium: Good division formation of true and pseudohyphae.

The hyphae have a bulbous, oval blastospore at the tip.

Formation of ascospores: 2 to 4 cap-shaped spores are formed in the ascus and connected hyphal cells resulting from the conjugation of two vegetative cells.

Glucose fermentation: weak assimilation: assimilates dl-lactic acid, succinic acid, citric acid, and nitrate.

Vitamin requirement: Yes Growth at 37°C: None Satucharomyces cerevisiae Br-1 Wort medium (25°C, 2 days culture): Cells are spherical and short oval.

Produces sediment. Wort agar medium (17°C, 1 month): Cream-colored to brown-gray fungal moss formation.

Ascospore formation: 2-4 ascospores are formed.

Fermentability: Glucose, sucrose, maltose, galactose, raffinose (3/1) fermentation.

Requires vitamins.

Nitrate assimilation ability: None.

In the present invention, one or two types of polysaccharide assimilating yeast
It is possible to add seeds or more to food manufacturing wastewater to decompose and assimilate sugars and proteins, thereby rapidly reducing them.

Polysaccharide-assimilating yeast is initially cultured in a general medium, and the grown yeast is added to wastewater. However, during wastewater treatment, the yeast proliferates due to the sugars in the wastewater, so it cannot be treated under optimal conditions. Even if the wastewater is subjected to acid flow, there is no need to add new yeast, and food manufacturing wastewater can be added as is.

The food manufacturing wastewater to be treated in the present invention may be used as it is, but in order to make the polysaccharide assimilating yeast work more effectively, it is necessary to Processing to remove SS and reduce COD may be performed as a step.

This first stage treatment method includes, for example, ferric chloride,
A coagulation-sedimentation method using polyaluminum chloride and polyacrylamide in combination is effective.

In this coagulation-sedimentation method, ferric chloride is added to food manufacturing wastewater while stirring it.

This addition reduces the pH, so use an alkaline solution such as caustic soda to adjust the pH to 6.5 to 7.5, preferably 70.
Adjust to

This pH is a necessary condition for large floc formation.

Due to the increase in iron ions, the remaining amount of COD decreases.

However, adding a large amount is not economical and also causes iron ions to remain in the treatment solution, which is not preferable.

Preferably, ferric ions must be added at a concentration of 100 to 300 ppm.

Under the above pH adjustment, 10% polyaluminum chloride
Approximately 200 to 300 ml of liquid is added per 1 m3 of waste water, and approximately 10 ppm of polyacrylamide is added to enlarge the floc.

The constant sedimentation speed of the generated flocs is approximately 5 to 6 m/
It is possible to separate and remove flocs by coagulation and sedimentation.

Incidentally, excessive use of a flocculant such as polyaluminum chloride or polyacrylamide will actually reduce the flocculating effect.

The treated water after separating the flocs has iron content of 0.1 ppm or less and almost no SS.

COD is removed by 97-98%.

That is, COD of 4,000 ppm in raw wastewater is reduced to about 100 ppm.

Although the coagulation-sedimentation method is described above as a desirable method, the first step method for removing SS and reducing COD in the method of the present invention is not limited to this, and may be a centrifugation method. There is no problem.

One or more types of polysaccharide-assimilating yeasts are added to food manufacturing wastewater that has undergone the first stage treatment or directly without any treatment; The bacteria are inoculated at a rate of 107 to 1012 cells per liter of wastewater.

In this case, liquid stirring is necessary to improve air absorption and contact between the yeast and the wastewater to be treated, and to aid the action and growth of the yeast.

The liquid may be stirred by air blowing.

If necessary, a phosphorus source or a nitrogen source such as ammonium chloride is added as a yeast nutrient to the present yeast.

If the yeast inoculum is low, yeast growth will be affected by CO2 in the wastewater being treated.
If the COD of the wastewater is several hundred ppm or less, it will take about two days, but if the amount of yeast inoculation is sufficient and the COD of the wastewater is 500 ppm or more, the treatment will be completed within one day.

The COD removal rate by this yeast removal is generally 90-95%.
It is.

For example, it is possible to process wastewater with a COD of 750 ppm from which SS has been removed to obtain treated water with a COD of about 70 ppm.

The wastewater produced by food production wastewater treated with polysaccharide assimilating yeast is sent to the activated sludge treatment tank either as it is or after being mixed with COD-reduced wastewater, etc., to more effectively remove COD. Ru.

At this time, it is possible to separate the yeast present in large quantities in the waste liquid to some extent, but it is more convenient from the standpoint of wastewater treatment operations to send the yeast directly to the activated sludge treatment tank without separating it. The yeast sent into the activated sludge treatment tank becomes a nutrient source or a vitality source for the activated sludge, increasing the activity of the sludge, and there is no separation of sludge from the structure, which is extremely convenient for activated sludge treatment.

The activated sludge treatment tank may be of any commonly used type, such as a lagoon or a trickling filter, but an activated sludge treatment tank in which activated sludge is attached to a structure such as a honeycomb is convenient to use.

Activated sludge treatment is carried out by circulating the honeycomb activated sludge zone while still containing yeast while aerating with an aeration pipe.

A circulation residence time of about 10 to 30 hours is sufficient.

Through this treatment, the COD of yeast treatment wastewater was reduced to 200ppm.
(including yeast cells) is reduced to 20 to 50 ppm (after natural sedimentation of microorganisms).

At this time, the microorganisms can be forcibly separated by coagulation and sedimentation using a flocculant, centrifugation using a centrifuge, etc., without waiting for natural sedimentation.

As a method for treating coagulation and precipitate using a coagulant, for example, the above-mentioned coagulation and precipitation method using a combination of ferric chloride, polyaluminum chloride and polyacrylamide is effective.

In this coagulation-sedimentation method, ferric chloride is added to treated wastewater containing microorganisms while stirring.

This addition decreases the pH, so use an alkaline solution such as caustic soda to adjust the pH to 6.5 to 7.5, preferably 7.
Adjust to 0.

This pH is a necessary condition for large floc formation.

Due to the increase in iron ions, the remaining amount of COD decreases.

However, adding a large amount is not economical and also causes iron ions to remain in the treatment solution, which is not preferable.

Preferably, it is necessary to add ferric ions at a concentration of 100 to 300 ppm.

Under the above pH adjustment, 10% polyaluminum chloride
Approximately 200 to 300 ml of liquid is added per 1 m3 of waste water, and approximately 10 ppm of polyacrylamide is added to make the flocs larger.

The constant sedimentation speed of the generated flocs is approximately 5 to 6 m/
It is possible to separate and remove flocs by coagulation and sedimentation.

The resulting precipitate is easily separated by filtration.

This microbial separation process reduces the final COD of wastewater to 5 to 3.
It becomes 0 ppm and can be discharged as is.

As described above, the method of the present invention reduces the COD of food manufacturing wastewater from 5 to 5 by treating all kinds of food manufacturing wastewater with polysaccharide-assimilating yeast and subsequently treating it with activated sludge.
It has been successfully reduced to 30 ppm, and has great benefits for food manufacturing wastewater treatment.

Further, following the yeast treatment, the yeast can be separated from the treated water by a method such as centrifugation, and the bacterial cells can be used for feed, etc.

Next, test examples of the present invention will be shown.

Test Example 1 Potato starch manufacturing wastewater with pH = 6.27 and COD 4700 ppm (clarifier - 2-fold dilution of wastewater) 25
0 ml was placed in each 500 ml beaker.

On the other hand, one platinum loopful of each strain used was inoculated into 50 ml of koji juice medium, pre-cultured at 30°C for 16 hours with shaking, and after the cultivation was completed, the bacterial cells were centrifuged, and further physiological saline was added for washing. This was used as bacterial cells for inoculation.

These bacterial cells were inoculated into each of the above flasks and cultured with aeration at 30°C for 48 hours. The resulting treated solution was centrifuged at 3,000G, the supernatant was taken out, and each COD was measured.
D removal rate was obtained.

The results are shown in the following table.

Test Example 2 Each of the wastewaters of Experiment Nos. 1 to 5 treated in Test Example 1 was treated with activated sludge (MLSS 3000 ppm) for a residence time of 72 hours and at an aeration rate of 0.5 liters per minute, and then led to a settling tank. After standing for 3 hours, the COD (ppm) of the supernatant was measured.

The results are shown in the following table.

Test example 3 In the same manner as Test Example 1, each bacterial cell for inoculation was prepared.

Pour 250 ml of tofu production wastewater with COD 1250 ppm and total sugar 800 ppm into each 500 ml beaker, inoculate each bacterial cell into each beaker, culture with aeration at 30°C for 48 hours, and centrifuge the resulting treated liquid at 3,000 G. It was separated, the supernatant liquid was taken out, and each COD was measured to obtain the COD removal rate.

The results are shown in the table below. Test Example 4 Activated sludge (MNSS 3,000 ppm) was added to each wastewater of experiment numbers 11 to 15 treated in Test Example 3, and while aeration was carried out at 0.5 l/min from an aeration pipe. After treatment for 24 hours, this was introduced into a precipitation tank, and after being left for 3 hours, the COD (ppm
) was measured.

The results are shown in the following table.

Example 1 Wastewater was prepared by mixing rice washing wastewater and sake tank washing water at a COD ratio of 5:3 (COD approx.
00ppm) Pichia acacia AM-37W in 19l,
FERM-PA3593, Hansenula anomala Y-1
, FERM-PNo. After inoculating and culturing 3594 at 107/ml each, wastewater was injected at a rate of 10.8ml/min, and the treated water overflowing over a residence time of 28 hours was continuously injected at a rate of 10.8ml/min at 24-25°C. Then, it is added to the next activated sludge treatment tank.

The activated sludge treatment tank has a honeycomb structure (volume: 3820, mechanical surface area: 0.68 m2), activated sludge is attached to this structure, and 9.5 liters of wastewater is aerated through the aeration pipe at an aeration rate of 4 liters/min. It is designed to circulate throughout the honeycomb structure.

Here, two treatment tanks are provided, and the residence time is 28 hours through the two tanks, and the treated wastewater is transferred to a sedimentation tank (volume: 3 liters).
Alternatively, the cells are introduced into a coagulation sedimentation tank and the bacterial cells are separated by natural sedimentation or coagulation sedimentation.

For coagulation sedimentation, polyaluminum chloride (60 ppm),
Add polyacrylamide (5 ppm) and adjust pH to 7-7
．． The aggregation treatment was performed by adjusting the concentration to 5.

The results obtained are shown in Tables 1 and 2.

As is clear from Tables 1 and 2, the COD of discharged wastewater
was reduced to about 9 to 29 ppm, showing good results.

In Tables 1 and 2: (1) Use of 60 ppm of polyaluminum chloride and 5 ppm of polyacrylamide (Acofloc A-110) (2)
Inflow, value after 15 hours (3) SS 470 ppm *Temperature was room temperature in all experiments Example 2 Hansenula anomala Y-1,
FERM-PNo. 3594 was inoculated at 10 7 /ml and cultured at 24 to 25° C. with stirring for 24 hours.

Meanwhile, while keeping the pH of rice washing wastewater (COD approximately 2000 ppm) at 7.0 to 7.5 with a caustic soda solution, 20 ppm of polyaluminum chloride and 5 ppm of polyacrylamide (Acofloc A-110) were sequentially added and allowed to stand to form flocs. This is separated by filtration to obtain wastewater with reduced COD (about 450 ppm COD).

Next, this was combined with the above culture solution and passed through the same two activated sludge treatment tanks as in Example 1, where it remained for 24 hours.
The treated wastewater is led to a settling tank or a coagulant-sedimentation tank, and yeasts are separated by natural sedimentation or coagulation-sedimentation.

For coagulation sedimentation, polyaluminum chloride (60 ppm),
Add polyacrylamide (5 ppm) and adjust pH to 7-7
．． 5, and agglomeration treatment was performed.

The results obtained are shown in Table 3.

As is clear from Table 3, the COD of the discharged wastewater is 20 to 5.
It was reduced to about 0 ppm, showing good results.

Example 3 Potato starch manufacturing wastewater (clarifier wastewater COD
2000-12100ppm) into the treatment tank, and add Hansenula anomala Y-1, FERM-PN to it.
o. After inoculating 3594 at 107/ml and culturing, 1 m
Wastewater is injected at a rate of 1/min, and while stirring at 24-25°C, overflowing treated water is continuously added to the next activated sludge treatment tank after a residence time of 24 hours.

Aeration and agitation treatment (residence time: 72 hours) is performed, and yeast is separated from the treated wastewater by natural sedimentation.

The supernatant liquid was discharged, but the COD of the treated water was 165 to 320 ppm after 12 days of continuous treatment.

Claims (1)

[Claims] 1 Adding one or more types of polysaccharide-assimilating yeast to food manufacturing wastewater (excluding sake brewing wastewater) to assimilate and consume organic matter, and then treating the resulting treated wastewater with activated sludge treatment. Characteristic methods for treating food manufacturing wastewater (excluding sake brewing wastewater), etc.