JPS6018479B2 - How to treat wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wastewater treatment method that can continuously, efficiently and stably treat 80D concentrated wastewater using photosynthetic bacteria (mainly purple non-sulfur bacteria).

Conventionally, biochemistry using microorganisms has been used to treat 80D concentrated wastewater, such as human waste, accumulated wastewater, or industrial wastewater, such as tofu factory wastewater, fishery processing wastewater, leather factory wastewater, bean paste factory wastewater, and silkworm production wastewater. treatment has been applied.

However, conventional biochemical treatment methods such as activated sludge method, trickling filter method, rotating disk method, etc.
In order to treat OD concentrated wastewater, for example, wastewater that is thicker than the BODIOOOO skin, a method has been used to dilute it by diving, but in this case, fresh water is required for dilution, and the amount of water due to dilution is Due to this increase, the processing equipment becomes extremely large, which has the disadvantage of increasing equipment costs, operating costs, and equipment area. As a method to solve this drawback, there are methods for non-dilution treatment of BOD-concentrated wastewater using photosynthetic bacteria, for example, Japanese Patent Publication No. 47-45885, Japanese Patent Publication No. 5
It is known from various publications such as 1-15347-. However, with these known non-dilution treatment methods, it is difficult to maintain photosynthetic bacteria in the photosynthetic bacteria treatment tank, and
There are major problems in carrying out continuous, efficient and stable treatment, and this has been a major hindrance to the practical application of conventional photosynthetic bacteria treatment methods. In other words, in the conventional method for treating BOD-rich wastewater using photosynthetic bacteria, as shown in the flow sheet of the process example in Figure 1, the photosynthetic bacteria in the photosynthetic bacteria treatment tank, which is an essential condition when performing photosynthetic bacteria treatment, are In order to maintain an absolute preponderance over heterotrophic bacteria, a portion of the treated solution or bacterial sludge after photosynthetic bacteria treatment is sent to a return culture tank under anaerobic and light conditions to activate photosynthetic bacteria. A method has been adopted in which the inoculum is continuously returned to the first tank of the photosynthetic bacteria treatment tank.

However, in such conventional return culture tanks, it is usually necessary to culture for about 24 hours or more under conditions of an anaerobic atmosphere and irradiation with light of around 30°C, which makes the equipment too large and is difficult to use in practice. However, there were major problems in maintaining a dominant presence of photosynthetic bacteria in the photosynthetic bacteria tank over a long period of time, such as the fact that the effect of the return culture tank was not stable. In view of these circumstances, the present inventors developed a method for treating BOO concentrated wastewater using photosynthetic bacteria (mainly purple non-sulfur bacteria), which allows photosynthetic bacteria in a photosynthetic bacteria treatment tank to be grown longer than ever before without the need for a conventional return culture tank. The present invention was arrived at as a result of intensive research to provide a wastewater treatment method that can maintain dominance for a continuous period of time. The photosynthetic bacteria in the photosynthetic bacteria treatment tank can be removed by returning the treated water in each tank from the second tank where the treatment tank is divided into three or more tanks to the tank immediately preceding each tank. The present invention relates to a method for treating wastewater, which is characterized in that wastewater treatment is carried out while continuously maintaining a stable and predominant amount of water.

The wastewater treatment method of the present invention is carried out through the following three steps, as shown in the process example flow sheet of FIG.

'1) BOD-concentrated wastewater is first put into the solubilization tank shown in 1 in Figure 2, and usually aerated with air for about 2 hours to equalize the water volume and 80D concentration, and at the same time Reduce the molecular weight of a substance (for example, by organic oxidation). The BOD concentration at this stage is 500 or more. ■ The wastewater that has been reduced in molecular weight and has a uniform BOD concentration is then processed into the second
It is transferred to the photosynthetic bacteria treatment tank shown in Figure 2, inoculated with photosynthetic bacteria, and heated with air.

At this time, the second part of the photosynthetic bacteria treatment tank divided into at least 3 cages, preferably 3 cages to 1 cage, as shown in 2 in Figure 2.
By returning a portion of the treated water from each of the above-mentioned premises from each tank after the rice mill to the rice grain immediately preceding each, the photosynthetic bacteria in the photosynthetic bacteria treatment tank can be maintained stably and dominantly for a long period of time. To efficiently and stably treat concentrated BOD wastewater continuously for a long period of time up to the wind level of about 80D and about 50. {31 B.O.
The wastewater treated to about D500 is further removed in a settling tank to remove suspended matter that can be settled and separated, and then subjected to any one of the activated sludge method, the catalytic oxidation method, the trickling filter method, or any combination thereof. The secondary treatment shown in 3 in FIG. 2 is carried out using the method described above, and the wastewater is treated to the desired wastewater standard of 80D. To explain in more detail the step [21], which is a feature of the present invention, the photosynthetic bacteria tanks 2 in FIG.
Preferably, a multi-tank division system of 3 to 1 tubes is explored, and the total tank volume of these many photosynthetic bacteria treatment tanks is determined based on the relationship between the BOD concentration of the raw wastewater and the 80D concentration of the treated water in the photosynthetic bacteria treatment tanks. Determine by taking into account the processability of

In addition, the normal 800 volume load is 1.5 to 10k9・BOD
The return amount of the treated water from each divided tank to the previous tank is usually set to about 5 to 200% of the original waste water amount, which is set within the range of /day. This is because if the return amount is less than 5%, the effect of the present invention cannot be maintained, whereas if the return amount is 200% or more, the effect of the present invention can be maintained, but the power cost associated with return increases, which is undesirable. Further, the amount of return in each of the above tanks may be set to be the same depending on the type of monkey waste water and the BOO concentration, or may be set to be different depending on the situation, and is not particularly limited. In the wastewater treatment method of the present invention, in order to maintain the photosynthetic bacteria in the photosynthetic bacteria treatment tank stably and dominantly for a long period of time and treat concentrated 80D wastewater efficiently and stably for a long period of time, As mentioned above, it is better to divide the photosynthetic bacteria treatment tank into at least 3 or more cells, preferably 3010 cells, and to have as many tanks as possible.The reasons for this are as follows.

That is, Figure 3 shows the aeration time and B
FIG. 3 is a diagram showing the relationship between OD concentration and the number of photosynthetic bacteria. As can be seen from FIG. 3, the position where the number of photosynthetic bacteria peaks changes depending on the change in the BOD concentration of raw wastewater. However, usually
When designing a treatment device, it is designed based on the maximum BOD concentration of the target wastewater, but in reality, it is inevitable that the BOD concentration of raw wastewater will fluctuate significantly below the set 80D concentration. Therefore, it is clear that the most efficient way to maintain a preponderance of photosynthetic bacteria in the photosynthetic bacteria treatment tank is to return the treated water from the location where the number of photosynthetic bacteria peaks. In reality, the peak position changes depending on changes in the BOD concentration of the raw wastewater, so if you divide the photosynthetic bacteria tank into many parts and return only from a specific tank, for example, from the last tank to the first As in the case of the prior art shown in FIG. 1, in which the photosynthetic bacteria are returned only to the waste, it is difficult to maintain a preponderance of photosynthetic bacteria in the area where the photosynthetic bacteria are treated. However, in the treatment method of the present invention,
Since the treated water from each tank is returned from each of the photosynthetic bacteria treatment tanks divided into as many units as possible to the photosynthetic bacteria treatment tank immediately preceding each tank, even if the 80D concentration of the raw wastewater varies, the maximum concentration in each tank will be maintained. This means that photosynthetic bacteria can be maintained in this state. As described in detail above, compared to the conventional wastewater treatment method using photosynthetic bacteria, the method for treating wastewater using photosynthetic bacteria of the present invention does not require a return culture tank, and also allows photosynthesis to occur within the photosynthetic bacteria treatment tank. It becomes much easier to maintain bacterial dominance, and the process is therefore simplified.
It has many advantages, such as low production costs and very simple maintenance, and its industrial value is great.

Furthermore, when processing human waste, by combining it with the "method for processing human waste" previously filed by the present applicant on November 30, 1970, the effect will be further demonstrated, resulting in an excellent processing system.

Furthermore, the present invention can also be applied to the treatment of wastewater from pharmaceutical and organic synthetic chemical factories. Next, the present invention will be explained in more detail with reference to Examples.

Example 1 **Using 80D concentration wastewater from Seimen Kogyo, it was solubilized by air aeration for 1 hour as shown in 1 in Figure 2, and then the BO of the photosynthetic bacteria tank was
D volume loading up to 3.0k9BOD for 80D concentration
For example, as shown in Figure 2, the treated water of each tank is transferred from each tank after the second tank to the tank immediately preceding each tank. Raw wastewater supply amount 3
0% was returned and processed.

At this time, the BOD concentration was varied in the range of 6,000 feet to 15,000 feet skin, and the amount of air aeration in the face tank was 2 states/X9.
- When setting BOD and starting operation, photosynthetic bacteria were inoculated into each of the 5 divided photosynthetic bacteria treatment tanks in an amount of 20% of the volume of each tank. The results are shown in Table-1.
For comparison, from the fourth grain divided into five grains according to the conventional treatment process, for example, as shown in Fig. 1,
Table 2 shows the results when 30% of the treated water was returned to the first tank via a return culture tank where it remained under anaerobic and light conditions for 24 hours.

The data in Tables 1 and 2 show the treatment status after one month of continuous treatment using the same raw wastewater and the same amount of blast air.

Table-1 Table-2 of operational results in the treatment process of the method of the present invention
Operation in conventional treatment process.

From the results in Tables 1 and 2, it can be seen that the method of the present invention has a much higher photosynthetic bacterial cell concentration and an excellent BOD removal effect than the conventional method.

[Brief explanation of the drawing]

Figure 1 is the conventional method, Figure 2 is the method of the present invention, and flow sheets for each example of the wastewater treatment process using photosynthetic bacteria. Figure 3 is the explosion time and photosynthetic bacteria as a function of concentration changes in BOD-rich wastewater. This is a relational diagram of changes in numbers, and the BOD concentration ranking of each curve in FIG. 3 is as follows. Curve {a}>Curve {b}>Curve {c->Curve [d}>Tai'ZuMai 3

Claims (1)

[Claims] 1. When treating BOD-rich wastewater using photosynthetic bacteria, the photosynthetic bacteria treatment tank is divided into three or more multi-tanks, and from each tank after the second tank, the treated water in each tank is transferred to the tank immediately preceding each tank. A wastewater treatment method characterized in that wastewater treatment is carried out by continuously and stably maintaining photosynthetic bacteria in a photosynthetic bacteria treatment tank in a dominant state by returning the water.