JPH02157097A - Bacteria flocculant and bulking control method - Google Patents

Abstract

PURPOSE:To prevent the bulking of activated sludge in a decomposition region by allowing flocculant producing bacteria belonging to the genus Rhodococcus or Nocardia and calcium chloide to be present in an org. waste water treatment system. CONSTITUTION:By allowing flocculant producing bacteria belonging to the genus Rhodococcus or Nocardia and calcium chloride to be present in an org. waste water treatment system using activated sludge, the bulking of activated sludge in the separation region of activated sludge and treated water is prevented. As a representative strain of flocculant producing bacteria belonging to the genus Rhodococcus or Nocardia, there is Rhodococcus erythropolice KR-256-2, FERM-PNo. 3923. When this org. waste water treatment method is used, the generation of filamentous fungi being a main cause of a bulking phenomenon is suppressed and the separation of activated sludge and treated water becomes efficient.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an organic wastewater treatment method, and more specifically, in an organic wastewater treatment method using an activated sludge method, flocculant-producing bacteria are used to prevent bulking of activated sludge. This invention relates to an organic wastewater treatment method that efficiently separates activated sludge and treated water.

(Prior Art and its Problems) Conventionally, activated sludge systems have been widely used as a method for treating wastewater containing various organic substances. This activated sludge method is a highly efficient treatment method and is the most widely used treatment method because it can economically obtain high-quality treated water.

1] The most important problem remaining in the two-part activated sludge system is the separation of treated water and activated sludge after treatment. Sedimentation separation 1 - Is it desirable that when the separation area is allowed to stand still, bulking and differential locking phenomena occur due to the growth of filamentous fungi, which reduces the flocculation effect of the activated sludge and makes the sedimentation separation of the activated sludge insufficient. This may cause the problem of activated sludge flowing out.

A known method for promoting the separation of activated sludge and treated water is to use polymer flocculants such as cationic polymers or inorganic flocculants such as polyvalent metal ions, but these flocculants cannot be biodegraded. Due to insufficient water quality, water is discharged together with treated water, leading to environmental pollution problems.

Therefore, an object of the present invention is to provide an organic υF water treatment method that can efficiently separate activated sludge without causing the activated sludge bulking phenomenon.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides an organic υ1 water treatment method using an activated sludge method, in which flocculant-producing bacteria belonging to the genus Rhodococcus or the genus Tucartia and calcium chloride are present in the treatment system, and in the separation area between activated sludge and treated water. The present invention is an organic wastewater treatment method characterized by preventing pulkinking of activated sludge, and a powdery hulkinking inhibitor obtained by freeze-drying a rhodococcus erythropolis nutrient solution.

(Effect) In the organic (J) water treatment method using flocculant-producing bacteria, by using calcium chloride together with flocculant-producing bacteria, the generation of filamentous fungi, which is the main cause of the hull kink phenomenon, is suppressed and active The separation of activated sludge and treated water becomes efficient, and furthermore, by setting the concentration of pH 1 flocculant-producing bacteria and calcium chloride in the range 11 to a specific range, the separation of activated sludge and treated water is significantly promoted.

In addition, the flocculant-producing bacteria used are Rhodococcus spp.
Erythropolis is the most preferred, and this flocculant-producing bacterium can be efficiently cultured in an open system in a fructose liquid medium, making industrialization possible in terms of cost.

Furthermore, even if the above-mentioned culture solution is freeze-dried and powdered, the number of viable bacteria will not decrease much, and if it is re-cultivated in condensed water, it will quickly proliferate, so there is no need for large-scale culture equipment for each processing facility, and it will not cause aggregation. It becomes possible to economically implement an organic wastewater treatment method using substance-producing bacteria.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The activated sludge organic wastewater treatment method used in the present invention is well known, and the present invention is not particularly limited and can be applied to any of these well-known organic wastewater treatment methods.

In addition, the flocculant-producing bacteria used in the present invention are
The flocculant-producing bacteria known in Japanese Patent Publication No. 29598, and which can be used in the present invention, may be any bacteria having activated sludge flocculation ability belonging to the genus Rhodococcus or the genus Tucartia, or a representative thereof. The strain is Rhodococcus erythropolis R-256-2,
FERM-P No. 3923 and Rhodococcus erythropolis KR-5-1, FERM-P No.

It is 3530. The 18 Nocardia erythropores were reorganized and reclassified as Rhodococcus erythropolis by the International Committee on Nomenclature of Microorganisms in 1980.

When inoculating and mixing Rhodococcus bacteria when used to prevent bulking of activated sludge, - For boat fishing, it is preferable to use bacteria that have been precultured (including !Ill culture) in the presence of the target wastewater substrate; There is no need for pre-incubation.

Although it is desirable to maintain the growth pH of the Rhodococcus bacteria inoculated and mixed in this way and to supply an appropriate nutrient source, it can be used for a certain period of time without adding any nutrient source. Examples of the nutrient include carbon sources, inorganic salts, inorganic nitrogen sources, organic nitrogen sources, vitamins, agricultural wastes, food industry wastes, fermentation waste liquids and residues, municipal garbage, and the like.

Wood fungi are particularly useful as they can be applied to all kinds of substrates, including general organic carbohydrates, urban sewage, industrial wastewater, hydrocarbons, filth, and environmental pollutants such as phthalates. The effect can be exerted simply by adding seed bacteria without culturing.

The culture medium for Rhodococcus bacteria includes carbon sources such as glucose, sucrose, blackstrap molasses, starch, and texturin, nitrogen sources such as ammonium sulfate, urea, greenhouse, peptone, and other nutritional sources such as inorganic salts, vitamins, and yeast extract. used. Culture may be liquid culture or solid culture. For liquid culture, pH = 4
Aeration and stirring are carried out at a temperature of 20 to 40°C at a temperature of about 8°C to 8°C.

After culturing for about several days, the culture is completed and a culture product is obtained.

When fishing by boat, the culture solution of the cultured bacterial cells obtained here can be directly added to the settling N tank of activated sludge method equipment. Alternatively, the culture solution may be concentrated or the bacterial cells may be suspended in the solution before addition.

Among the above flocculant-producing bacteria, Rhodococcus erythropolis is particularly preferred for the present invention, and Rhodococcus erythropolis will be described below as a representative example.

The first feature of the present invention is that calcium chloride is used in combination with the flocculant-producing bacteria (Rhodococcus erythropolis) described in "-", and the combination of calcium chloride and activated sludge and treated water in the organic wastewater treatment method The generation and proliferation of filamentous fungi, which are the main cause of bulking, can be suppressed in the separation area. Therefore, the present invention is particularly effective in treating wastewater where filamentous fungi are likely to occur in the treated water.

The second feature of the present invention is that the pH in the separation region where activated sludge and treated water are to be separated is preferably set to 8 to 9. In other words, when the pH is 8 or less, coagulation and separation of activated sludge is not promoted much even if calcium chloride is used in combination with flocculant-producing bacteria, and on the other hand, even when the pH is 9 or more, the flocculation and separation of activated sludge similarly increases depending on the pH. This is undesirable because it does not promote the activation of activated sludge and also reduces the activity of the activated sludge.

A third feature of the present invention is that the concentration of calcium chloride in the separation region is preferably 0.25% by weight or more, more preferably 0.25 to 1.0% by weight. If the concentration is less than 0.25%, the flocculation effect is insufficient even if the amount of flocculant-producing bacteria is increased, and even if it is 1.0% by weight or more, no increase in the flocculation effect depending on the concentration is observed. .

The fourth feature of the present invention is that the amount of flocculant-producing bacteria added to the culture solution is 0.5% by weight or more, preferably 0.5 to 10% by weight. The concentration of flocculant-producing bacteria is 0.5
If it was less than 10%, a sufficient flocculating effect could not be obtained, and even if it was added in excess of 10%, the flocculating effect could not be improved depending on the amount added.

It should be noted that the flocculating substance-producing bacteria used in the present invention is thought to produce flocculating substances and the product exerts the flocculating effect, but the culture solution can be filtered through a 0.45 membrane filter to remove bacterial bodies. A similar effect can be obtained by using a solution containing

Experiments were conducted to determine suitable pH, flocculant-producing bacteria, and calcium chloride concentration as described below, and the results are shown in FIGS. 1, 2, and 3.

It is well known that the above-mentioned flocculant-producing bacteria can be cultured in a sterilized pure culture system, but in order to industrially utilize these flocculant-producing bacteria, it is necessary to efficiently cultivate them in an open system where various bacteria are mixed. It is necessary to be able to cultivate it.

The present inventor investigated these points and found that it is possible to efficiently culture in an open system in a specific liquid medium.

As a culture method, flocculant-producing bacteria (Rhodococcus spp.
Erythropolis) was precultured by shaking culture in the following liquid medium and was investigated as a test microorganism.

Toshu dark roasted reduced fructose 10g/uK211PO,
+ 5 g / I'K112
PO42g/11 Mg5O40,2g/fl (NH4)2504 0,5g
/ R-yeast extract 0.5g/fiN
aCI O, Ig/u Next, 150 mfi of the above liquid medium was placed in a 500 mM square flask, and 5 mJZ of seed bacteria was inoculated and cultured with shaking at a temperature of 30°C. The titer and bacterial growth of the culture solution were 5,000 mg kaolin/
fL solution 80m, C 10% CaCl2 solution 10m11. After adding 05 ml of culture solution, stir well by inverting with a 100+nJ1 measuring cylinder, and adjust the pH of the reaction solution to NaO.
Adjust the pH to 8 with H, then stir the whole thing well again and let it stand, and measure the turbidity (OD550) of the clear water after 5 minutes.
The amount of bacterial growth was determined by 0D660. In addition, as a comparative example, ○I) iso
and OD ar,o were calculated. As a result, the results shown in Figure 4 were obtained.

From the results shown in Figure 4, the titer of the known phthalate-based medium is 26% of that of the pure culture system, while the titer of the fructose medium open culture system is 88%. It was found that it was possible to proliferate for 7 minutes even in an open system using a system culture medium. In addition, the best results were obtained when the pH of the medium was 8 to 9, especially 8.5. Further, a culture time of about 5 days is sufficient.

Furthermore, in order to make the flocculant-producing bacteria as described above easier to use industrially, it is preferable that the flocculant-producing bacteria can be handled as a powder rather than as a culture solution. In the present invention, an attempt was made to powderize the culture solution of flocculant-producing bacteria using a freeze-drying method. That is, the culture solution cultured in the fructose liquid medium at 200 m°C was placed in an IJl freeze-drying container, and freeze-dried and powdered using a freeze dryer (manufactured by Taihei Kagaku).

The obtained powder was condensed by adding sterile distilled water to the same weight as before freeze-drying, and the percentage of viable particles was examined: 57.1% after storage for 11 months and 32.3% after storage for 1 month. , a result of 30.6% was obtained after storage for 6 months. In addition, 5mM of the above condensed sample was added to 100m2 of fructose liquid medium and cultured with shaking at 30°C.The amount of bacterial growth was examined. The cells proliferated to a certain degree, and the aggregation activity became the same.

Therefore, according to the present invention, the flocculant-producing bacteria can be sufficiently handled as a powder, and the flocculant-producing bacteria can be restored with simple culture equipment. Industrialization is possible.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

By applying flocculant-producing bacteria to artificially generated bulking sludge in a continuous mixed culture tank,
The bulking suppression effect was investigated by varying the amount and method of addition of calcium chloride and flocculant-producing bacteria.

Experimental method (a) In the sample raw water experiment, BOD 100g/J with the composition shown in Table 1 below.
1 of concentrated raw water was prepared, diluted with tap water to a concentration suitable for the treatment conditions, and used.

and 1 - (Substrate composition of synthetic υF water) Glucose 720 7.3 280 450 480
Starch 400 7.7 145 260 220 Peptone 3207.315511030042 Urea
16---8 Phosphoric acid-potassium 40---9 Synthetic wastewater -
8,158082010005010 (The units of numerical values in the table are mg/x except for p11) It has been verified that the above synthetic wastewater has a substrate composition that is extremely likely to cause filamentous bulking, and it was selected based on the results. There are things.

(b) In the activated sludge experiment, activated sludge that had been acclimatized in a batch-type mixing culture tank was used as the activated sludge using the synthetic wastewater shown in Table 1 above.

This activated sludge has good settling properties.

When this activated sludge is continuously cultured under treatment conditions not shown in Table 2 below, the BOD load (g/u-El
) o, a Water amount (fl / El
) 8BODfi degrees (mg/u
) 8o.

7. 5RT of sludge (['') s Sedimentation @MRT (1lr) 6. False branching is often seen in filamentous microorganisms in activated sludge, and cell diameter is 0.8
1.2 μm to 1.2 μm, the cell shape is oval and Crumb staining is (-), and according to the classification method of Eikclboom and Jenkins, Spl + oeroj, i Iusn a j
: Classified as a II S.

(c) Experimental equipment For experiments, the aeration tank capacity is 8 degrees and the sedimentation amount is as shown in Figure 6.
A continuous mixing culture tank 21 made of transparent PVC was used. The sample raw water was continuously supplied to the aeration tank at a predetermined concentration and volume using a metering pump. Aeration is always carried out in the aeration tank by air.
I used an air stone to make it stand up. The water temperature was at room temperature and was between 22 and 25° C. during the experiment.

(d) Addition conditions Activated sludge is in a bulking state from the start of water flow (SVI400
m, Q/g or more), calcium chloride and a culture solution of flocculant-producing bacteria were added under the addition conditions shown in Table 3 below, and the palkink suppression effect was examined from the oral change in SVI of activated sludge.

The addition method was to mix a 25% calcium chloride solution and a flocculant-producing bacterial culture solution in an amount that matched the addition conditions, put it into an aeration tank, and adjust the pH to 8.5 to 90 with INNa0t. The culture solution was cultured with shaking in a fructose liquid medium for 5 days.The titer of this culture solution was 2.2 to 25.

”3-1 (addition conditions) γ7 4-1 0.062 0 Addition for 5 days 2
0.25 0 Added for 5 days 3
0.62 0 Added for 5 days 4
0.62 2 Added once 5 0.6
2 5 Added once 6 0.62
10 Added once 7 0.62
0 *8
0.62 2 *9
0.62 5
*10 0.62 10
**After adding the amount shown on the left once, 0.25% calcium chloride was added for 5 days from the next day.

(e) Analysis The items shown in Table 4 below were measured.

Sample Analysis items Sludge MLSS, 5V3o, micrograph Treated water pH, TOC Results and discussion (a) Examination of the amount of calcium chloride added The amount of calcium chloride added was 0.062.0.25.06
2% was added once a day for 5 days, and the bulking suppressing effect was examined. Figure 7 shows 5V30. MLSS,S
This shows oral changes in VI.

No improvement effect on the sedimentation compaction of activated sludge was observed under the addition conditions of 0.062 to 0.25% calcium chloride, but under the addition conditions of 0.62%, the SV began to decrease from the 31st addition, and sedimentation continued until the 9th day. The patient's sex improved, and the SV increased again. Furthermore, as the SV decreases, microscopic observation shows that filamentous microorganisms (Sphoerotilus na.
1, ans) decreased, it seems that the addition of a large amount of calcium chloride has the effect of inhibiting the growth of filamentous microorganisms.

(I+) Effect on inhibiting bulking caused by flocculant-producing bacteria The amount of calcium chloride added was kept constant at 0.62%, and the amount of flocculant-producing bacteria culture solution was changed to 2.5.10%. It was investigated. The results are shown in FIG.

A sustained effect of improving sedimentation compaction and inhibiting bulking was shown depending on the amount of culture solution added.

FIG. 9 shows the results of a comparison of changes in SVI over time when 0.62% calcium chloride and 5% culture medium were added, with continuous flow of raw water, and with air aeration.

Immediately after addition, the SVI was 500ml due to the aggregation effect of the culture solution.
/g to 100ml/g.

After that, the coagulation effect persists even after 24 hours in the air aeration state, or the cohesive force decreases over time when raw water is injected, resulting in an SVI of 400 m11 at 24 tlrJ and 4.
/g, the sedimentation property of the sludge returns to near its original state. The pH also decreased from 8.8 immediately after addition to 7.6 after 241+r. The reasons why the flocculation effect decreases when raw water flows in are as follows: Proliferation of filamentous bacteria 2) Disintegration of flocs by air 3 Decrease in pH 4) Outflow of calcium ions to the outside of the aeration tank system 5) Coagulation culture solution This is thought to be due to dilution and leakage out of the system.

Figure 10 shows the change over time in the concentration of residual calcium ions in the aeration tank when 062% calcium chloride and 5% culture solution were added.

It was found that about 25% was accumulated in the sludge, and the remaining 75% was discharged to the outside of the system together with the treated water. In a continuous mixed culture tank, in order to sustain the effect of flocculant-producing bacteria, it is necessary that calcium ions exist in the system and the pH is 8.0 or higher. The effect of suppressing the bulking of flocculant-producing bacteria was investigated under conditions where calcium chloride was supplemented. Figure 11 and 1
Figure 2 shows that the amount of calcium chloride added was fixed at 0.62%, and the culture solution of flocculant producing bacteria was added once at 0 to 10%, and then only 0.25% of calcium chloride was added for 5 days to obtain the bulking suppressing effect. This is the result of consideration.

No sustained suppressive effect was observed under the condition of adding 2% culture solution (titer 2.2 to 25), but under the condition of adding 5.10%, the SV began to decrease 5 days after addition, and after that, the SV of the sludge was reduced for more than 20 days. Good sedimentation continued and a sustained effect was observed.

However, it goes without saying that the amount of culture solution added largely depends on the agglutination titer of the culture solution. Therefore, it goes without saying that the amount of culture solution added does not necessarily need to be 5% or more. Regarding the influence on the treatment function shown in FIG. 12, the reason why the treatment performance deteriorates when the flocculant-producing bacteria is added at 2% or less is due to the decrease in the MLSS concentration due to the outflow of sludge. Therefore, when the sedimentation properties of sludge were improved by adding 5% or more of flocculant-producing bacteria, the treatability was maintained in a good state. However, as mentioned above, the amount of culture solution added is not limited to 5% or more.

The above results indicate that the sedimentation compaction of bulking sludge was improved due to the synergistic effect of calcium chloride's growth-inhibiting effect on filamentous microorganisms and flocculant-producing bacteria's aggregation-promoting effect.

(Effects) According to the present invention as described below, in the method for treating wastewater from a battering machine using flocculant-producing bacteria, by using calcium chloride together with the flocculant-producing bacteria, filamentous bacteria, which is the main cause of the hull kink phenomenon, can be eliminated. The generation of activated sludge and treated water is suppressed, and the separation of activated sludge and treated water becomes efficient. Furthermore, the separation of activated sludge and treated water is made possible by controlling the pH of the separation area, the concentration of flocculant-producing bacteria, and calcium chloride within specific ranges. is promoted even more significantly.

In addition, the flocculant-producing bacteria used are Rhodococcus spp.
Erythropolis is the most preferred, and this flocculant-producing bacterium can be efficiently cultured in an open system in a fructose liquid medium, making industrialization possible in terms of cost.

Furthermore, even if the above-mentioned culture solution is freeze-dried and powdered, there is little decrease in the number of viable bacteria, and by re-cultivating it in condensed water, it quickly proliferates and exhibits agglutinating potency. No culture equipment is required, and it becomes possible to economically implement the organic υ1 water treatment method using flocculant-producing bacteria.

[Brief explanation of the drawing]

1 to 5 and 7 to 12 are diagrams showing the results of examples of the present invention, and FIG. 6 is a diagram showing the apparatus used in the present invention. Applicant Yuki Iizuka, Director General of the Agency of Industrial Science and Technology

Claims (6)

[Claims] (1) In an organic wastewater treatment method using the activated sludge method, flocculant-producing bacteria belonging to the genus Rhodococcus or the genus Nocardia and calcium chloride are present in the treatment system, and activated sludge is An organic wastewater treatment method characterized by preventing bulking. (2) Maintaining the pH of the activated sludge separation area at 8 to 9;
The concentration of the culture solution of flocculant-producing bacteria is 0.5 to 10% by weight, and the concentration of calcium chloride (CaCl_2) is 0.
．． The organic wastewater treatment method according to claim 1, wherein the amount is 25 to 1.0% by weight. (3) The organic wastewater treatment method according to claim 1, wherein the wastewater to be treated is wastewater that is likely to generate filamentous fungi. (4) The organic wastewater treatment method according to claim 1, wherein the flocculant-producing bacteria is Rhodococcus erythropolis. (5) The organic wastewater treatment method according to claim 1, wherein the culture solution of Rhodococcus erythropolis is cultured in an open system in a fructose liquid medium. (6) Powdered anti-bulking agent obtained by freeze-drying a culture solution of Rhodococcus erythropolis.