JP2891850B2 - Wastewater treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for treating wastewater of various low-molecular and high-molecular substances, including organic substances. More specifically, at the start-up operation of the wastewater treatment device,
The present invention relates to a method for treating wastewater that can cope with temporary fluctuations of inflow wastewater during steady operation and has a deodorizing effect.

[0002]

2. Description of the Related Art Conventionally, for example, there is an activated sludge method as a typical method of treating organic wastewater, and a number of modified methods have been reported and implemented according to the type and composition of organic substances.

[0003] The basis of this method is the oxidation of organic matter by the respiration and growth of microorganisms. A large amount of air is supplied to maximize the treatment speed, and at the same time, a large amount of microorganisms generated are removed as sludge, and wastewater is removed. It is released as water that does not contain organic matter dissolved in water.

[0004]

In the biological treatment method represented by the activated sludge method, when starting the operation of the apparatus,
A seed fungus, generally called "seed sludge", is transplanted. This uses sludge generated from a similar treatment generator, depending on the nature of the wastewater. When a particular microorganism is determined to be effective, a culture of that microorganism is used.

[0005] However, in the organic wastewater, other microorganisms already compatible with the environment of the wastewater predominantly dominate, so that the inoculum microorganisms are inhibited from growing and die in this new environment. Many. Therefore, conventionally, in order to make the inoculum dominant in such an environment, the inoculation of the inoculant has a great disadvantage that it takes a long period of time, for example, about one month. Further, when sludge is used, it is necessary to activate the sludge by giving it an adsorptivity to organic pollutants, so that it has been necessary to sufficiently pass oxygen for a long time to form flocs. That is, in the conventional activated sludge method, in order to start the operation of the organic wastewater treatment apparatus, it takes time for the propagation of inoculum and the formation of flocs, which has been a serious problem in terms of wastewater treatment workability and treatment efficiency.

[0006] Also, during normal operation of the wastewater treatment apparatus, the growth of microorganisms is inhibited by the external environment such as temperature, light, and various germs, and the required amount of cells cannot be obtained. This was unfavorable in terms of supply. Conventionally, in this case, a breeding tank was installed at the site, culture was performed using a culture medium in this tank, and liquid cells were produced, and this was dealt with by injecting the cells weekly or daily. There is a problem in terms of stable supply of refuse, and the operation in the breeding tank takes time and labor as in the case of starting the operation of the processing apparatus, and there is a problem in terms of workability. In the activated sludge flocks,
It is not easy to insert the liquid cells, and most of them are discharged as supernatant, which is inefficient and requires a large amount of cells to restore the normal growth of microorganisms. There was.

[0007] Furthermore, during normal operation of the wastewater treatment apparatus, the inflow rate, components,
Water quality often changes considerably due to fluctuations in temperature and concentration, as well as seasonal fluctuations. Water quality changes
This greatly affects microorganisms in the treatment equipment, causing a situation such as a decrease in treatment capacity and an abnormality in treated water.

As a means for recovering this, conventionally,
Various measures have been taken, such as stopping the inflow of wastewater, increasing the amount of aeration, removing sludge, introducing a large amount of liquid bacterial cells, and sequentially subculturing them. In many cases, it cannot be recovered, and when a large amount of liquid cells are used, a large amount of medium is required, and a large culture tank is required, which is a problem. In addition, the operation of the wastewater source may be stopped, but it is often difficult to actually stop the operation of the machine. Therefore, conventionally, when the water quality changes during the normal operation of the wastewater treatment apparatus, there is no excellent method that can effectively cope with the change.

Further, in the conventional method, microorganisms are predominantly hard to exist, so that low-molecular substances, sulfur compounds,
It has been difficult to biologically decompose amine substances, butyric acid, mixed substances of acetic acid and alcohol, and the like with the microorganism.
Therefore, deodorization measures are based on the concealment method and the adsorption method,
Therefore, the deodorizing effect was not always satisfactory.

SUMMARY OF THE INVENTION It is an object of the present invention to greatly improve the workability and efficiency of wastewater treatment during a start-up operation or a normal operation of a wastewater treatment apparatus, and to provide an abnormal treatment capacity when water quality changes. An object of the present invention is to provide a method for treating wastewater that can effectively cope with the decrease and is excellent in deodorizing effect.

[0011]

As described above, the cause of poor workability and treatment efficiency in conventional wastewater treatment is that microorganisms existing in the wastewater treatment tank hydrolyze macromolecules, This is presumed to be dominant and predominantly present, which is to suppress the growth of microorganisms having wastewater treatment capacity. Furthermore, when the culture solution of the microorganisms is added to the wastewater treatment tank and mixed, the dilution solution is diluted and discharged as a supernatant before entering the floc. Therefore, under the environment of such wastewater, the amount of low-molecular organic acids is increasing more and more.

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, during the start-up operation or steady-state operation of the wastewater treatment apparatus, or when the water quality changes due to fluctuations in the treatment capacity, A non-fluid water-soluble gel mass transplanted with microorganisms having a wastewater treatment ability is brought into contact with wastewater containing organic matter, and the microorganisms grow inside the water-soluble gel mass in a state where the microorganisms are shielded from the external environment of the wastewater. At the same time, by adopting a treatment method in which the microorganisms inside the gel mass are gradually released into wastewater through dissolution from the outer surface of the water-soluble gel mass, the water quality can be quickly restored. The inventors have found that the problem can be solved by returning to the state, and have completed the present invention.

In the treatment method of the present invention, the wastewater treatment apparatus is preferably used in any one of a filtration method, an activated sludge method and a trickling filter method, or a combination thereof, but is not limited thereto. In addition, the water-soluble gel mass in which the microorganisms are transplanted may be placed in a wastewater treatment tank, a treatment pond, a filter bed, a filtration tank, a pipe, or the like so as to appropriately contact the wastewater, and the contact method is not particularly limited. When the contact is made in the wastewater treatment tank, the water-soluble gel mass does not need to be distributed throughout the treatment layer. .

[0014] When the wastewater treatment apparatus is provided with a sludge settling tank, the sludge settling tank is provided with the sludge settled in or on the sludge surface.
It is desirable to install this water-soluble gel mass transplanted with microorganisms having a wastewater treatment capability.

The microorganism used in the present invention can be applied to any microorganisms that can grow as an organic substance as a carbon source and a hydrogen donor. In particular, at least one of the genus Rhodobacter, Rhodopseudomonas, Rhodospirillium and Chromium is used. Microorganisms containing one or more are preferred.

The water-soluble gel mass is preferably a water-soluble polymer such as polyvinyl alcohol or water-soluble silicic acid, but is not particularly limited. However, the water-soluble gel mass used in the present invention is not limited to any water-soluble gel mass, but may be a gel mass that dissolves immediately in wastewater or, conversely, a sparingly water-soluble gel mass. must not. If it dissolves immediately in the wastewater, dissolution in the wastewater precedes the growth of the microorganisms and loses the opportunity for the microorganisms to grow in the gel mass, while it is insoluble or hardly soluble or excessively dissolved. This is because, in a delayed gel mass, the growth in the gel mass proceeds, but the grown microorganisms are hardly released into the wastewater and diffused. In short, the microorganisms are brought into contact with the wastewater and grown inside the water-soluble gel mass while being shielded from the external environment of the wastewater, and at the same time, the microorganisms inside the gel mass are exposed to the outer surface of the water-soluble gel mass. It must be a non-flowable, water-soluble gel mass that can be slowly released into wastewater through dissolution from the wastewater. In order to obtain such a non-fluid water-soluble gel mass, for example, in the case of a water-soluble polymer such as polyvinyl alcohol, it can be achieved by adjusting the number and molecular weight of hydroxyl groups.

[0017]

According to the present invention, at the time of start-up operation of a wastewater treatment apparatus, a non-fluid water-soluble gel mass transplanted with microorganisms having a wastewater treatment ability is brought into contact with wastewater containing organic substances, and the microorganisms are dissolved in the water. At the same time as growing in a state in which the wastewater is shielded from the external environment inside the water-soluble gel mass, and gradually releasing the microorganisms inside the gel mass into the wastewater through dissolution from the outer surface of the water-soluble gel mass. Since it is a wastewater treatment method, it is not necessary to multiply inoculum in advance in the start-up operation of the wastewater treatment apparatus as in the past, and the wastewater can be treated immediately without forming sludge floc. , Greatly improves workability.

Further, according to the present invention, during the steady operation of the wastewater treatment apparatus, the immobilized water-soluble gel mass transplanted with microorganisms having a wastewater treatment capability is brought into contact with the wastewater treatment device, and the microorganisms are brought into contact with the wastewater inside the water-soluble gel mass. This is a treatment method in which the water-soluble gel mass is propagated in a state of being cut off from the external environment and gradually released into wastewater through dissolution from the outer surface of the water-soluble gel mass. Also,
If this method is used, as in the past, a breeding tank is installed at the site to produce a liquid bacterial cell, and it is not necessary to supply it every week or every day. There is an advantage that the amount of cells can be supplied stably. Also, as in the start-up operation of the wastewater treatment device, the microorganisms can be expanded in self-propagation without suppressing growth from other microorganisms present in the wastewater, and can easily enter the sludge floc. Since it is possible, the yield of the amount of bacteria is extremely high without being discharged as a supernatant unlike the conventional case, and the effect is exhibited with a small amount as compared with the conventional case.

Further, the present invention provides a method for controlling the occurrence of an abnormal situation such as a change in water quality during a normal operation of a wastewater treatment apparatus.
The wastewater is brought into contact with a non-fluid water-soluble gel mass transplanted with microorganisms having a wastewater treatment ability, and the microorganisms are grown inside the water-soluble gel mass in a state of being shielded from the external environment of the wastewater. At the same time, since the water-soluble gel mass is gradually released into the wastewater through dissolution from the outer surface of the water-soluble gel mass, the inflow of the wastewater is stopped, the aeration amount is increased, sludge is removed, etc. Even without it, it can self-proliferate in altered water quality and achieve effective biological degradation for organic matter. In addition, there is no need to introduce a large amount of liquid cells as in the past, and there is no need to install a large cultivation apparatus, so that the amount of cells can be significantly reduced, and workability and economic efficiency are good with a small amount of use. is there.

Further, according to the method of the present invention, unlike the conventional deodorizing method using a masking method or an adsorption method, a low-molecular substance that emits an odor, a sulfur compound, an amine substance, a mixed substance of butyric acid, acetic acid and alcohol, and the like are used. It can be effectively degraded by predominant microorganisms.

[0021]

FIG. 1 is a process diagram showing one embodiment of a method for treating organic wastewater according to the present invention. In the figure, 1 is a raw water tank, 2 is a screen, 3 is an organic nutrient microorganism tank, 4 is a measuring tank, 5 is a wastewater treatment tank, 6 is a sludge sedimentation tank, and 7 is a sludge storage tank.

Wastewater from a factory plant is first received in a raw water tank 1, then pumped by a pump, and passed through a filter cloth type screen 2 to remove coarse suspended substances. Next, the wastewater passing through the screen is sent to the organic nutrient microbial tank 3, where the high molecular organic matter contained in the raw wastewater is aerated and aerobic heterotrophic bacteria convert starch into sugars and protein into amino acids. The fat is decomposed into acetic acid, propionic acid, etc., so that the microorganism can be easily treated. Next, the treated wastewater is pumped from the organic nutrient microorganism tank 3 by a pump, weighed in the measuring tank 4, and then sent to the wastewater treatment tank 5.

In the wastewater treatment tank 5, aeration is performed by a blower using sludge, and a biochemical reaction such as adsorption and absorption of organic substances, formation of bacteria, oxidation of cytoplasm, etc. is caused under aerobic conditions. In particular, in this example, a culture solution consisting of Rhodopseudomonas capsuletatus, a microorganism having wastewater treatment ability, was transplanted to a non-flowable water-soluble gel mass containing polyvinyl alcohol as a main component, and these microorganisms were included. Since the water-soluble gel mass 8 is placed in the sludge in the wastewater treatment tank 5, the microorganisms having the wastewater treatment ability are isolated from the external environment of the wastewater in the water-soluble gel mass. While proliferating, it gradually releases and diffuses into wastewater through dissolution from the outer surface of the water-soluble gel mass, so it is superior to the number of other microorganisms around the water-soluble gel mass. Occupy the area, and an area that is easy to proliferate appears. Therefore, the growth of the microorganisms occurs more and more, and the growth area expands.

Therefore, during the start-up operation of the wastewater treatment apparatus,
When the water-soluble gel mass filled with the microorganisms is charged,
Microorganisms that immediately become inoculum self-proliferate in the water-soluble gel mass, and the inoculum becomes dominant early in the wastewater. In addition, since the inoculum microorganisms self-proliferate in the water-soluble gel mass, biological treatment has already progressed in an aerobic atmosphere by aeration before sludge flocs are completely formed. After the formation of the flocs, the organic compounds easily enter the flocs and biologically decompose the adsorbed organic substances under an aerobic atmosphere.

The waste liquid thus treated in the wastewater treatment tank 5 is pumped as sludge to a sludge settling tank 6, where a large amount of microorganisms generated in the wastewater treatment tank 5 are settled as sludge. Remove and drain the supernatant.

The sludge accumulated in the sludge settling tank 6 is returned to the wastewater treatment tank 5 as returned sludge by the pump 9 or stored in the sludge storage tank 7 as drawn sludge.

When the processing capacity of the microorganisms in the wastewater treatment tank 5 decreases during the operation of this apparatus, the microorganisms having the wastewater treatment capacity are transplanted into the wastewater treatment tank 5 as in the start-up operation. If the non-fluid water-soluble gel mass is placed and microorganisms are allowed to proliferate inside the water-soluble gel mass and gradually released from the outer surface of the water-soluble gel mass to the wastewater, the microorganism is present in the wastewater. It is possible to expand self-proliferation without suppressing growth from other microorganisms. When the water-soluble gel mass is completely dissolved in the wastewater, the supply of microorganisms is stopped, so if a new water-soluble gel mass is added as necessary,
A position to start a new activity is immediately established, and it can be dealt with simply by existing as a so-called satellite-like state.

Next, using the wastewater treatment apparatus described above, the treatment method according to the present invention and a conventional treatment method using liquid cells were tested under the same conditions. During the start-up operation, the liquid cells were initially used at a volume of 1 liter of liquid cells / m ³ tank volume, multiplied up to 500 times on site, and then trained with wastewater for trial operation. In the present invention, a water-soluble gel mass having a capacity of 200 g / m ³ was implanted with photosynthetic bacteria, and was acclimated with wastewater for trial operation. Sludge in the wastewater is 1000 ppm.

As a result, in the conventional treatment method using liquid cells, it took about one month to grow the cells in the field and about two weeks to form flocs. In the examples, it was recognized that the wastewater treatment could be started immediately independently of the growth period and floc formation independently, and the treatment period was shortened for about 45 days.

Next, with respect to the raw water in the raw water tank 1, the waste water in the organic nutrient microorganism tank 3, and the treated water discharged from the sludge sedimentation tank 6, the daily changes in the start-up operation of the waste water treatment apparatus over 21 days are shown. Tracked. FIG. 2 shows the biochemical oxygen demand C of the treated water discharged from the sludge settling tank 6.
FIG. 3 is a graph showing the daily change in OD (ppm), FIG. 3 is a graph showing the daily change in the biochemical oxygen demand COD removal rate (%) of the treated water, and FIG. (P
pm), FIG. 5 is a graph showing the daily change in the amount of suspended solids SS (ppm) of the raw water and the wastewater in the organic nutrient microorganism tank 3, and FIG. 6 is a graph showing the wastewater in the wastewater treatment tank 5. FIG. 7 is a graph showing the daily change of the average dissolved oxygen amount DO (ppm), and FIG. 7 is a graph showing the daily change of the visibility (cm) in the wastewater of the tank.

The COD removal rate (%) is defined as the difference between the COD of the treated water discharged from the sludge settling tank 6 from the wastewater in the organic nutrient microorganism tank 3 and the COD of the wastewater in the organic nutrient microorganism tank 3. The higher the removal rate, the better.

As shown in FIG. 2, the COD of the treated water gradually decreases from the first day of the test run, and it is recognized that the effect of the method using the water-soluble gel mass of the present invention has appeared. However, at this time, since no effective sludge floc was formed in the wastewater treatment tank, the COD sharply increased on the fourth day. Then, the same amount of the same water-soluble gel mass was again placed in the wastewater treatment tank. As a result, as shown in FIG. 2, the COD continued to decrease over a long period of time.

Although not shown, flocs of sludge started to form in the wastewater treatment tank after about two weeks.
Accordingly, at the time of steady operation, the same amount of water-soluble gel mass of about 2 g / m ³ tank volume was installed every week. as a result,
At the time of steady operation, it was found that wastewater treatment can be effectively performed with a water-soluble gel mass having a volume of about 2 g / m ³ .

Further, as a result of observing the odor, it was confirmed that the deodorizing effect was remarkably exhibited.

The present invention is not limited to the above embodiment.

[0036]

As described above, according to the present invention, microorganisms having a wastewater treatment ability are transplanted to the wastewater during the start-up operation of the wastewater treatment apparatus, during the steady operation of the wastewater treatment apparatus or when the water quality of the wastewater treatment apparatus changes. Contacting the non-fluid, water-soluble gel mass
At the same time as allowing the microorganisms to grow inside the water-soluble gel mass while being shielded from the external environment of the wastewater,
Since it is a method of releasing slowly into wastewater through dissolution from the outer surface of the water-soluble gel mass, unlike the conventional method,
The workability and efficiency of the wastewater treatment are greatly improved, and even if the treatment capacity is reduced, it can be effectively dealt with, and the original performance can be restored.

Since the transplanting capacity of the microorganism is very small,
In addition to being able to reduce the amount of bacterial cells, it is extremely easy to transport and handle, and because it is not diluted with wastewater, it can be easily applied to start growth and achieve stable supply. In addition, since there is no need to install a large culture device, the present invention is also excellent in terms of economy.

Further, according to the method of the present invention, unlike the conventional deodorizing method using the concealing method or the adsorption method, a low-molecular substance that emits an odor, a sulfur compound, an amine substance, a mixed substance of butyric acid, acetic acid and an alcohol, etc. The effect of effectively decomposing microorganisms that predominantly exist is also remarkably exerted, and therefore, it greatly contributes to the technical field.

Although the present invention is a method capable of effectively dealing with wastewater containing organic matter, it is not necessarily limited to the wastewater, and even wastewater containing other components can be effectively treated by selecting microorganisms. Can deal with.

[Brief description of the drawings]

FIG. 1 is a process diagram showing one embodiment of a method for treating wastewater according to the present invention.

FIG. 2 is a graph showing COD of treated water over time.

FIG. 3 is a graph showing the change over time in the COD removal rate of treated water.

FIG. 4 is a graph showing a daily change of a suspended solids amount SS of treated water.

FIG. 5 is a graph showing a daily change of a suspended solids amount SS of raw water.

FIG. 6 is a graph showing the daily change of the suspended solids amount SS of the wastewater in the organic nutrient microorganism tank.

FIG. 7: Average dissolved oxygen amount D of wastewater in a wastewater treatment tank
It is a graph which shows the daily change of O.

Claims (6)

(57) [Claims] At the start-up operation of the wastewater treatment apparatus, a non-fluid water-soluble gel mass transplanted with microorganisms having a wastewater treatment capability is brought into contact with the wastewater, and the microorganisms are brought into the water-soluble gel mass inside the water-soluble gel mass. A wastewater treatment, wherein the microorganisms are grown in a state of being shielded from an external environment, and at the same time, the microorganisms inside the gel mass are gradually released into the wastewater through dissolution from the outer surface of the water-soluble gel mass. Method. 2. During the steady operation of the wastewater treatment apparatus, a non-fluid water-soluble gel mass transplanted with microorganisms having a wastewater treatment capability is brought into contact with the wastewater, and the microorganisms are brought into contact with the wastewater inside the water-soluble gel mass. A wastewater treatment, wherein the microorganisms are grown in a state of being shielded from an external environment, and at the same time, the microorganisms inside the gel mass are gradually released into the wastewater through dissolution from the outer surface of the water-soluble gel mass. Method. 3. When the water quality of the wastewater treatment apparatus changes, a non-fluid water-soluble gel mass transplanted with microorganisms having a wastewater treatment ability is brought into contact with the wastewater, and the microorganisms are brought into contact with the wastewater inside the water-soluble gel mass. A wastewater treatment, wherein the microorganisms are grown in a state of being shielded from an external environment, and at the same time, the microorganisms inside the gel mass are gradually released into the wastewater through dissolution from the outer surface of the water-soluble gel mass. Method. 4. The wastewater treatment method according to claim 1, wherein the wastewater treatment apparatus is at least one of a filtration method, an activated sludge method, and a trickling filter method. 5. A wastewater treatment apparatus provided with a sludge settling tank, wherein the water-soluble gel mass according to claim 1, 2 or 3 is installed in the sludge of the sludge settling tank or on the sludge surface. 5. The method for treating wastewater according to 1, 2, 3, or 4. 6. The method for treating wastewater according to claim 1, wherein the microorganism contains at least one selected from the group consisting of Rhodobacter, Rhodopseudomonas, Rhodospirillium, and Chromium.