JPH07308689A - Method for treating waste water containing fats and oils - Google Patents

Abstract

PURPOSE:To improve reduction efficiency of content of fats and oils by adding Candida famata US-238 to waste water containing fats and oils to culture it under aerobic conditions, thereby reducing content of the fats and oils. CONSTITUTION:Candida famata US-238 is added to waste water containing fats and oils to culture it in an aerobic conditions, at pH 4-9, at culturing temperature of 20-42 deg.C, thereby reducing content of fats and oils in the waste water. The Candida famata US-238 is a strain which is separated from soil of Inno Island, Hiroshima Prefecture, Japan and is isolated by a predetermined screening method. Fats and oils in waste water are extracted with n-hexane, as an extracting agent, and concentration of the fats and oils in the waste water is set in the range of about 200-500mg/l, whereby a preferable result can be obtained. That is, waste water having concentration of 200mg/l or less is processed by concentrating it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying domestic wastewater or industrial wastewater such as food processing plants, and more particularly to a method for treating oil-containing wastewater using microorganisms.

[0002]

2. Description of the Related Art Conventionally, an activated sludge method has been known as a biological wastewater treatment method. In this method, microorganisms are adhered to and proliferated on the flocs surface of activated sludge mainly composed of highly cohesive bacteria. Disassemble.

[0003]

However, in the conventional wastewater treatment by the above-mentioned activated sludge method, there is no problem in reducing the concentration of proteins and sugars among the organic substances in the wastewater, but domestic wastewater or foods. There is a problem in that it is difficult to efficiently treat wastewater containing fats and oils such as industrial wastewater at a processing factory in a relatively high concentration.

That is, in the conventional wastewater treatment method, the present situation is that the oil / fat-containing wastewater is passed through the oil / fat separation tank in advance, the oil / fat is separated and recovered, and the oil / fat is separately treated as industrial waste. , Such processing steps are complicated,
In addition to costs, transactions as waste are beginning to be shunned.

Therefore, an object of the present invention is to solve the above-mentioned problems and efficiently reduce the fat and oil content by a relatively simple treatment method which can reduce the cost of the fat and oil-containing wastewater. It is to let.

[0006]

The inventor of the present application has made extensive studies on a method for treating oil-and-fat-containing wastewater, and as a result, by utilizing a specific microorganism, namely Candida famata US-238, It was found that the content can be efficiently reduced, and the present invention has been completed.

In other words, in order to solve the above-mentioned problems, in the present invention, wastewater containing oil and fat is added to Candida Famata US-238 (FERM P-1397).
4) was added and cultured under aerobic conditions to reduce the fat and oil content in the waste water.

In the above means, it is preferable that the culture condition is pH 4-9 or the culture temperature condition is 20-42 ° C.

The details will be described below. Candida Famata US-238 (Cand used for this invention
idafamata US-238) was adopted by the inventor of the present application as the one that most efficiently achieves the object of the present invention as a result of separating microorganisms from soil collected in various parts of Japan and examining their assimilation ability for oils and fats. The isolated strain was isolated from the soil of Innoshima Island, Hiroshima Prefecture, and was isolated by the following screening method.

[Candida Famata US-238
Screening method] The soil separation sample was added to the medium A having the following composition, and the mixture was cultured at 30 ° C. for 2 to 3 days. Then, for those in which the growth of microorganisms was observed, the accumulation culture was performed in the same medium to obtain the oil and fat assimilation ability. Accumulated strong bacteria. And
Confirm the reduction amount of oil and fat in the upper layer by centrifuging the culture solution, apply the culture solution containing the bacteria with the highest oil and fat assimilation ability on a plate medium composed of the same composition, after culturing, colonies Was isolated and fractionated to obtain the target strain.

Composition of medium A: (pH 8.0) Fish oil 1 ml Glucose 3.5 mg Ammonium nitrate 35 mg Dipotassium hydrogen phosphate 14 mg Magnesium sulfate 7 mg Yeast extract 7 mg Tap water 7 ml Bacteria of the strain obtained above The scientific properties are as follows.

(1) Morphological properties Morphology Oval or globular cells are one or several in series Size (1-6) × (2-6) μ Budding multipolar budding Pseudohyphae Not developed in cornmeal medium Spontaneous mycelium formation is observed No ascospore formation is observed (2) Cultural properties (YM liquid medium) Precipitation and film formation are observed (3) Giant colony observation (YM agar medium) Good growth Upstanding trapezoid Surface condition Smooth tone Milky white (4) Physiological properties Growth pH 3-9 Optimum pH 5-7 Growth temperature Up to about 42 ℃ Optimum temperature 20-35 Nitrate assimilation-Growth in vitamin-deficient medium-Diazonium blue B Color reaction- [fermentability] glucose-galactose-sucrose-maltose-lactose-raffinose-inositol- [assimilation] glucose + galactose + sucrose + Maltose + cellobiose + trehalose + lactose-raffinose + melitithose + starch + D-xylose + L-arabinose-D-ribose + L-rhamnose + erythritol-ribitol + D-mannitol + succinate + citrate- + citrate. From the results, the isolated strain was identified as Candida famata, and this strain was designated as Candida famata US-238.
(Candida famata US-238).

This strain has been deposited at the Institute of Biotechnology, Institute of Biotechnology, Institute of Industrial Science and Technology as "Microbial Accession No. Life Research Institute No. 13974 (FERM P-13974)".

The oil / fat in the waste water in the present invention is a substance which is well known as an oil / fat extraction solvent and is extracted with n-hexane.

The content of fats and oils in the wastewater to be treated containing such fats and oils is not particularly limited, but good results have been obtained by treating wastewater having a fats and oils concentration of 200 to 5000 mg / l. . That is, wastewater having a relatively high fat concentration may be treated as it is,
Wastewater of low concentration such as less than mg / l concentrates fats and oils,
For example, if the oil and fat content is increased to about 5000 mg / l, the treatment amount is small and it is efficient.

In the case of wastewater containing fats and oils, as a pretreatment, a fats and oils separation tank for separating and removing fats and oils by a natural flotation device or a pressure flotation device is provided. In the present invention, the fats and oils separation tank is used as a culture tank. Required amount of Candida Famata U
S-238 is added, pH 4-9, preferably pH 6-
7. The oil and fat is decomposed and removed by aeration and stirring at a temperature of 20 to 42 ° C, preferably 30 to 35 ° C.

In this way, the activated sludge can be added to the treated water with reduced fat and oil and sent to the air race tank of the known activated sludge apparatus to decompose and remove organic substances other than fat and oil.

When the oil / fat content is relatively low, for example, with 200 mg / l of waste water, the above pretreatment is not carried out, and the present bacteria are added to the waste water discharged from the first settling tank together with the activated sludge, By treating with an aeration tank under appropriate pH and temperature conditions, fats and oils and other organic substances can be decomposed and removed at the same time. Then, the water treated in this way is sent to the second settling tank, and the supernatant water is discharged.

Normally, the fat-and-oil-containing wastewater also contains nitrogen, phosphorus, and micronutrients, so that the growth of Candida famata US-238 is maintained by these, but if necessary, vitamins, minerals, etc. Nutrients may be added. In particular, when the oil and fat content is reduced by the present bacterium alone as a pretreatment, in order to achieve efficient culture conditions,
It is desirable to adjust the nutritional conditions to maintain the sufficient growth of this bacterium.

[0020]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. [Examples 1 to 5] Rapeseed oil was contained as an oil and fat, and n
-A predetermined amount of Candida famata US-238 was added to a medium having the following composition containing 5000 mg / l (hereinafter, this concentration unit is referred to as ppm) as a hexane extract, and after culturing for 5 days under the following conditions: The amount of n-hexane extracted was examined, and the results are shown in Table 1.

[Medium] 0.5 g of rapeseed oil (5000 pp
m) Ammonium sulphate 0.5 g Magnesium sulphate 0.10 g Yeast extract 0.10 g 0.25 M phosphate buffer 100 ml [Experimental conditions] Sample to be tested Medium to be added to the medium 1 Platinum loop Culture method Shake culture Sample volume to be supplied 100 ml (Using a flask with a capacity of 500 ml) Culture temperature 30 ° C. pH 4, 6, 7, 8, 9 Culture days 5 days

[0022]

[Table 1]

As is clear from the results shown in Table 1, the treatment methods of Examples 1 to 5 have a fat and oil treating ability under the conditions of pH 4 to 9, and the optimum conditions are around pH 6 (Example 2). I understand.

[Examples 6 to 7] After culturing for 5 days under exactly the same conditions except that lard or palm oil was used as the oil and fat in place of rapeseed oil in Example 2, n of lard or palm oil in the medium was used. The amount of hexane extracted (ppm) was examined, and the results are shown in Table 2.

[0025]

[Table 2]

As is clear from the results shown in Table 2, when treating wastewater containing fats and oils that are solid at room temperature, compared to Examples 1 to 5 of the system to be treated that contains fats and oils that are liquid at room temperature, It can be seen that although the reduction efficiency is poor, it is a good wastewater treatment method.

[Examples 8 to 10, Comparative Example 1] Examples 8 to
For No. 10, the sample volume was 50 ml (100 ml volume flask was used), rapeseed oil, lard or palm oil was adopted as the fat and oil, and the culture temperature was 20 ° C, 30 ° C, 4 ° C.
After culturing for 5 days, the conditions were set to 0 ° C. and the stirring was carried out with a stirrer in exactly the same manner as in Example 2 in which the pH was 6 during the culturing, and then rapeseed oil, lard or palm oil in the medium was used. Extraction amount of n-hexane (ppm)
Was examined and the results are shown in Table 3.

In Comparative Example 1, the culturing temperature was set to 10 ° C., and the other conditions were cultivated in the same manner as in Example 8 to examine the extraction amount (ppm) of n-hexane, and the results are shown in Table 3. I also wrote it down.

[0029]

[Table 3]

As is clear from the results shown in Table 3, the treatment efficiency in the wastewater treatment method of the present invention was found to be good when the treatment temperature was 20 to 40 ° C, and the result was not good at 10 ° C.

[Examples 11 to 16] Example 2 (pH 6)
The treatment conditions are adopted, and the oil and fat concentration is 5 to 30% by volume (w /
V), when a system to be treated containing oil and fat at a very high concentration was treated, the amount of extracted n-hexane (g) after 5 days of treatment and the amount of oil and fat decomposed by this treatment (g) were examined,
The results are shown in Table 4.

[0032]

[Table 4]

As is clear from the results shown in Table 4, in the treatment methods of Examples 11 to 16, the fats and oils were stably reduced in spite of the high oil and fat concentration conditions, and were used in the present invention. It can be seen that the ability of microorganisms to assimilate fats and oils hardly deteriorates even in a high concentration of fats and oils.

Example 17 The treatment conditions of Example 2 (pH 6) were adopted, that is, rapeseed oil was adopted as the oil and fat, and the sample volume was 8 ml (using a 40 ml test tube),
Other than that, the treatment was carried out under the same conditions as in Example 2, and the extraction amount of n-hexane for each treatment day was examined, and the results are shown in Table 5.

[0035]

[Table 5]

As a result, it can be seen that the number of days of treatment is 1 to 2 days, and there is a sufficient effect of reducing the fat and oil content.

[Example 18] As an actual wastewater, the wastewater of our company (Ueda Oil Co., Ltd.) oil and fat factory containing 5300 mg / l of n-hexane extract was used as the wastewater to be treated, and after adjusting to pH 6, Treatment was carried out for 3 days under the treatment conditions exactly the same as in No. 17 (that is, the same as in Example 2), and the amount of extracted n-hexane after that was examined.

As a result, n contained in the wastewater after the above treatment
The amount of hexane-extracted substance was reduced to 150 mg / l, and it was confirmed that this treatment had a remarkable effect of reducing the fat and oil content.

[Comparative Examples 2 to 10] Using the treatment conditions of Example 17, instead of Candida famata US-238, the following nine kinds of typical microorganisms (strains) known as lipid-assimilating yeasts were used. ) Was used, and the other conditions were the same as in Example 17, and the amount of n-hexane extracted for each treatment day was examined. The results are also shown in Table 5.

[Microorganisms (Strains) Used as Comparative Examples] (1) Candida bombicola IFO 10243 (2) C.I. famata IFO 0664 (3) C.I. famata IFO 0856 (4) C.I. rugosa IFO 0750 (5) Pichia candensis IFO 0973 (6) P. kluyveri IFO 1165 (7) Rodotorula javanica IFO 10285 (8) Trichosporon pullulans IFO 1232 (9) Yarrowia lipolytica IFO 1548 As well as the results of Table 5, it is clear that the candida is 38. According to the method, the efficiency of assimilating fats and oils was not sufficient.

[Comparative Examples 11 to 19] Using the treatment conditions of Example 11 and treating a high-to-be-treated system having a fat and oil concentration of 5% by volume (w / V), the microorganisms (1) to Using (9), the amount of extracted n-hexane (g) after 5 days of treatment and the amount of fats and oils decomposed by this treatment (g) were examined, and the results are shown in Table 6.

[0042]

[Table 6]

As is clear from the results shown in Table 6, in the treatment methods of Comparative Examples 11 to 19, the amount of oil and fat decomposed was small, and in contrast to this, the above-mentioned Candida famata U was used.
It can be seen that the treatment method of Example 11 using the S-238 strain is extremely superior.

[0044]

[Effect] As described above, the present invention efficiently increases the oil content of oil-containing wastewater by a simple method of adding a predetermined strain of Candida famata to the oil-containing wastewater and culturing under aerobic conditions. There is an advantage that the oil / fat-containing wastewater treatment method that is well reduced and is low in cost and excellent in practical use can be provided.

Further, when the culture treatment is carried out under the prescribed pH and temperature conditions, the treatment can be carried out more efficiently, and when other useful microorganisms are used in combination, the treatment method becomes more advantageous. It can be said that this is a high-value invention.

Claims (3)

[Claims] 1. An oil and fat comprising adding Candida Famata US-238 (FERM P-13974) to waste water containing the oil and fat, and culturing under aerobic conditions to reduce the oil and fat content in the waste water. Treatment method of wastewater containing. 2. The method for treating oil-and-fat-containing wastewater according to claim 1, wherein the culture conditions are pH 4-9. 3. The method for treating waste oil-containing wastewater according to claim 1, wherein the temperature condition for culturing is 20 to 42 ° C.