JP2000210074A - Acclimation of degrading microorganism, obtaining of acclimated microorganism and degradation of organic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily obtain an acclimated degrading microorganism in a short time by adding a pH adjustor and an organic compound which is the object of degradation into a liquid so as to provide the pH within a prescribed range according to the fluctuation of the pH and acclimating a degrading microorganism capable of fluctuating the pH by the biodegradation of the organic compound in the liquid. SOLUTION: This method is to acclimate a degrading microorganism capable of degrading an organic compound in a liquid and fluctuate the pH of the system by biodegrading the organic compound with the degrading microorganism. A pH adjustor and the organic compound which is the object of the degradation are added into the liquid so as to provide a pH 6-8 as a prescribed range thereof during the acclimation to thereby readily afford the acclimated degrading microorganism in the shortest time. Furthermore, the method for acclimating the degrading microorganism comprises further installing a pH sensor 6 for measuring the pH and a pH controller 7 for feeding a culture medium 4 containing the pH adjustor and the organic compound which is the object of the degradation according to the fluctuation of the pH in a treating vessel 1 for the organism equipped with an aerating mechanism 2 and a circulating flow forming unit 3, then adding a spawn of the degrading microorganism to the treating vessel 1 for the organism, culturing the degrading microorganism while keeping the pH within the prescribed range and capturing the discharging degrading microorganism in a precipitation tank 5 and affording the acclimated degrading microorganism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for acclimating or decomposing organic compound-decomposing bacteria, and a method for decomposing organic compounds.

[0002]

2. Description of the Related Art There are several biological treatment methods for organic compounds contained in wastewater, and the most versatile method is the activated sludge method. This method is an aerobic treatment method, and includes a storage tank for storing raw water as the water to be treated, and a pH for adjusting the pH of the water to be treated supplied from the storage tank.
It is composed of an adjusting tank, a biological treatment tank for biologically treating the water to be treated, the pH of which is adjusted by the pH adjusting tank, and a sedimentation tank for supplying the treated water treated in the biological treatment tank. In the pH adjusting tank, a pH meter for measuring the pH in the pH adjusting tank, a pump for supplying a pH adjusting solution into the pH adjusting tank, and a pH measured by the pH meter are used. And a control device for controlling the supply amount of the pH adjusting liquid by the pump. In such a treatment apparatus, after the water to be treated is temporarily stored in a storage tank, a pH adjusting solution is added in the pH adjusting tank until the water reaches a predetermined pH value, and then supplied to the biological treatment tank. You. The water to be treated undergoes oxidative degradation by aerobic microorganisms present in the activated sludge in the biological treatment tank, and the oxygen required for this is sequentially supplied by an aeration device disposed in the biological treatment tank. The to-be-processed water treated in the biological treatment tank is then separated into sludge containing microorganisms and treated water in a sedimentation tank, and the sludge separated and separated is returned to the biological treatment tank or pulled out of the system. There are many types of aerobic microorganisms in activated sludge, and their composition differs depending on the composition of organic compounds in the water to be treated. This becomes the most suitable microbial composition for the water to be treated after long-term acclimation. As a result, activated sludge has the greatest feature of being able to treat various organic compounds at once, but on the other hand, has low treatment capacity per unit volume, cannot cope with rapid changes in the water to be treated, and has a high oxygen content. There are drawbacks such as increased supply power cost. In particular, the incorporation of a highly loaded compound may significantly amplify the disadvantage. Examples of such a compound include dimethyl sulfoxide having a sulfur atom in the molecule (hereinafter, DMSO). DMSO is difficult to decompose, and when oxygen supply is reduced, it is reduced to generate malodorous substances such as dimethyl sulfide. Therefore, in order to surely treat DMSO, it is necessary to increase the residence time and increase the oxygen supply amount, If the compound is treated simultaneously with other compounds by the method, the treatment cost will be further increased. In addition, in the case of DMSO or the like, if the substrate concentration exceeds a certain level, an inhibition of the organism occurs, which may cause a decrease in the decomposition rate of other organic compounds. Also DM
When SO is decomposed, it usually produces sulfuric acid.
Decreases, but the larger the biological treatment tank, the larger the p
It becomes difficult to supply the alkaline solution and maintain the pH stably while appropriately maintaining H. On the other hand, DMSO is easy to separate because it is used for special purposes such as cleaning of electronic materials such as semiconductors. Therefore, it may be more efficient to treat wastewater containing a compound having a high load and being separable from other wastewater individually. Some individual processing methods and processing systems for DMSO have been proposed so far. For example, a method of adjusting the pH of water to be treated containing an organic sulfur compound and then treating the treated water in a biological treatment tank (Japanese Patent Application Laid-Open No. 7-265890), a method of oxidizing and then performing a biological chemical treatment (Japanese Patent Application Laid-Open No. JP-A-8-238497), PV in which microorganisms acclimated in DMSO are comprehensively fixed.
A processing method using a gel mainly composed of A (JP-A-7-31)
No. 991).

[0003]

However, in the case of individual treatment, the concentration of the compound is naturally higher than in the activated sludge method, which causes problems such as the inhibition of the growth of ordinary degrading microorganisms. Only when these disadvantages are overcome, efficiency of the processing can be obtained. In other words, in order to efficiently decompose the compound, the most important factor is how to acclimate and acquire a microorganism having the highest ability that is most suitable for the decomposition conditions in a short time. Is currently relying on experience and intuition.

[0004]

That is, the present invention comprises the following constitutions.

[0005] This is a method of acclimating an organic compound-degrading decomposing bacterium in a liquid, wherein the degrading bacterium biodegrades the organic compound to change the pH of the system. A method for acclimating degrading bacteria, characterized by adding a pH adjuster and an organic compound to be decomposed to a liquid so as to be within a certain pH range. "," The pH range in the acclimated liquid is 6-8. " The method of acclimating degrading bacteria of the degrading bacteria, the method of acclimating any one of the preceding degrading bacteria, wherein the pH adjusting agent of the solution contains an alkali agent. The method for acclimating any of the degrading bacteria, wherein the organic compound to be decomposed by the degrading bacteria contains an organic sulfur compound. " A method for obtaining an acclimatized bacterium, which is characterized by being taken out. ", Method for decomposing organic compounds characterized by the addition of decomposed organic compound decomposing bacteria by the method described in the one after acclimatization, to a solution containing the decomposing bacteria. "
"A method for decomposing the organic compound, wherein the organic compound to be decomposed is an organic sulfur compound."

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As the organic compound to be decomposed in the wastewater on which the method of the present invention effectively acts, those whose pH significantly fluctuates to one side due to biodegradation are preferably used. Examples of the decrease in pH due to biodegradation include, in addition to DMSO, organic sulfur compounds such as dimethyl sulfone, and nitrogen compounds such as primary to tertiary amines and quaternary ammonium salts. Organic acid salts are mentioned.

The pH adjuster is used when the organic compound to be decomposed itself has a buffering action as an adjuster, for example, when the pH is lowered by biodegradation, or when it is an alkaline compound, or when the pH is increased by biodegradation. When it is an acidic compound, it is not particularly necessary to add it, but it does not have such an effect, that is, when it is neutral, various alkaline agents are used when the pH is reduced by biodegradation, and when it is increased, acids are used. . Either organic or inorganic can be used, but when it is not preferable to add a new load to decomposition, it is safe to use an inorganic agent. Inorganic alkali agents include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, etc.In the case of wastewater containing iron and other metal salts, strong alkali precipitates, If this affects the growth of the microorganism, it is preferable to add a weak acid such as sodium bicarbonate. In general, inorganic acids such as sulfuric acid and hydrochloric acid are used as the acids. It is important that the amount of addition is slightly smaller than the amount of a variable substance generated when the substance fluctuates by biodegradation, that is, an acid or an alkali. If the amount is the same or more, the compound in the treatment tank is completely decomposed and the pH no longer fluctuates.

[0008] As other additives, if substances necessary for the growth of microorganisms such as various nitrogen sources, phosphorus sources, sulfur sources and trace inorganic metal salts are not included in the organic compounds to be decomposed, they are added as necessary. Is preferred.

The conditions at the time of acclimation can be freely selected according to the situation in the wastewater of each organic compound to be decomposed.
With respect to organic sulfur compounds such as O, the pH to be adjusted is preferably pH 4-10, more preferably pH 6-8. The concentration of organic compounds to be decomposed at the time of habituation is 100p
It is preferably from pm to 10% (ppm and% mean weight basis unless otherwise specified), and more preferably from 300 ppm to 1%. The water temperature is preferably from 10 to 40C, more preferably from 25 to 35C. Since DMSO-degrading bacteria are usually aerobic microorganisms, it is necessary to supply oxygen. At this time, the dissolved oxygen concentration in water is preferably 1 ppm or more, more preferably 2 ppm or more. Decomposing bacteria are naturally generated only by aeration, but the acclimatization period of the decomposing bacteria can be shortened by adding seeds such as soil exudate and sludge at the start of acclimation.

[0010] As an apparatus used for acclimatization of the decomposing bacteria, an aeration mechanism for constantly aerating the wastewater retention region in the treatment tank, a pH sensor and a controller for adjusting pH, and a p-type device.
A device equipped with a pump for supplying an organic compound to be decomposed containing an H adjustor can be used. Further, by providing a sedimentation tank, sedimentable microorganisms or microbial aggregates can be concentrated in the treatment tank. The smaller the volume of the sedimentation tank, the better the sedimentation property of the concentrated microorganisms. Moreover, if it is small, it can be incorporated in the processing tank. If the sedimentation is good, the treatment can be carried out even with a shorter residence time, so that even a low-concentration organic compound to be decomposed can be treated without impairing the treatment amount per unit volume.

After acclimation by the method of the present invention, the organic compound can be decomposed by adding an organic compound to be decomposed to the solution containing the decomposing bacteria.

[0012]

Embodiments of the present invention will be described below.

In FIG. 1, a biological treatment tank 1 is for biological treatment of a pH adjusting agent and a culture medium 4 which is an organic compound to be decomposed, and an aeration mechanism for constantly aerating a drainage retention region in the biological treatment tank 1. 2 and a cylindrical circulation forming body 3 provided above the aeration point in the drainage retention area, and the flow rate is controlled by a flow meter (not shown). Further, a pH for measuring pH is set in the biological treatment tank 1.
A sensor 6 and a pH controller 7 serving as a supply unit for supplying the culture medium 4 into the biological treatment tank 1 in accordance with a change in pH are provided. Further, a sedimentation tank 5 for capturing the decomposing bacteria flowing out of the biological treatment tank is provided in the biological treatment tank 1.

Example 1 A processing apparatus having the form shown in FIG. 1 was prepared, and dimethyl sulfoxide 0.2% and NaHCO 3 were prepared.
₃ 0.36%, NH ₄ Cl 0.04%, K ₂ HPO ₄
A medium 4 composed of 0.02% and 0.02% of MgCl ₂ was prepared and charged into the treatment tank 1. DMS as the inoculum
The sludge of the activated sludge device in the factory that is treating the O-containing wastewater was added, and the culture was started at 25 ° C. The pH was adjusted to 7 and the pH controller 7
A part of the culture medium was supplied through. The DMSO concentration in the treatment tank was measured by gas chromatography. After 3 days, the processing volume per day with respect to the processing tank capacity (L) is 0.14 L, and the DMSO concentration of the processing solution is 1000 p.
pm (0.04 g-DMSO / L / day)
After 30 days, the sedimentation of the sludge in the treatment tank became good, the treatment amount was 1.8 L, and the DMSO concentration of the treatment liquid was 450 ppm (7 ppm).
g-DMSO / L / day). At this time, the dry weight (MLSS) of the sludge was 20 g / L.

Example 2 Condition of acclimation in Example 1 (7 g
(DMSO / L / day), the treatment was carried out by changing the pH to be adjusted to 6 to 8. As a result, the treatment amount was maximum at pH 6.5 to 7.5, 20% at pH 6.0, and 20% at pH 8. 4
5%.

[Embodiment 3] The acclimatized state of Embodiment 1 (7 g-
(DMSO / L / day), the pH to be adjusted was set to 7, and the concentration of the medium to be supplied was diluted to 2000 to 500 ppm. As a result, the treatment could be carried out at 2000 to 1000 ppm without impairing the treatment amount. %Met. The dry weight of the sludge at this time is 20 to 26.
g / L.

[0017]

According to the present invention, the pH in the biological treatment tank is adjusted.
The pH is continuously adjusted to be within a certain pH range with fluctuation.
Since the adjusting agent and the organic compound to be decomposed are supplied, the limit amount that can be processed in the acclimatized state at that time can always be supplied automatically. Therefore, the acclimatization of the decomposed bacteria can be performed in the shortest time, and thus, the acclimatized bacteria can be easily obtained. In addition, if the processing is performed by this method, the maximum processing amount is always maintained, so that the apparatus can be downsized.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a DMSO processing apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Biological treatment tank, 2 ... Aeration mechanism, 3 ... Circulating body, 4 ... Medium, 5 ... Settling tank, 6 ... pH sensor, 7
..PH controller

Claims (7)

[Claims] 1. A method of acclimating an organic compound-degrading decomposing bacterium in a liquid, wherein the degrading bacterium biodegrades an organic compound to change the pH of the system.
A method for acclimating a decomposing bacterium, comprising adding a pH adjuster and an organic compound to be decomposed to a liquid so as to fall within a certain pH range with the fluctuation of H. 2. The method according to claim 1, wherein the pH of the solution is in the range of 6 to 8. 3. The method for acclimating degrading bacteria according to claim 1, wherein an alkaline agent is contained in the pH adjuster of the acclimating liquid. 4. The method for acclimating a degrading bacterium according to claim 1, wherein the organic compound to be decomposed by the degrading bacterium contains an organic sulfur compound. 5. A method for obtaining a cultivated bacterium, which comprises removing the bacterium obtained after acclimation of the degrading bacterium according to any one of claims 1 to 4. 6. A method for decomposing an organic compound, comprising acclimating a degrading bacterium by the method according to any one of claims 1 to 4, and then adding an organic compound to be decomposed to a liquid containing the degrading bacterium. 7. The method for decomposing an organic compound according to claim 6, wherein the organic compound to be decomposed is an organic sulfur compound.