JPS60153998A - Waste water treating agent and its preparation - Google Patents

Abstract

PURPOSE:To prevent the reduction of nitration bacteria due to the intake by relatively large microorganisms, by including and immobilizing the flocculated substance, which is obtained by flocculating nitration bacteria in a floc form by using an org. high-molecular flocculant, in a polyarylamide gel. CONSTITUTION:Nitration bacteria are flocculated by using an org. high-molecular flocculant to form a floc like flocculated substance having a particle size of 100mum or more while said flocculated substance is included and immobilized in a polyacrylamide gel to prepare a waste water treating agent. In the aforementioned org. high-molecular flocculant, polyvinyl pyridine hydrochloride or polyethylene imine is designated as a cationic high-molecular flocculant and sodium polyacrylate is designated as an anionic high-molecular flocculant. The immobilization of the flocculated substance of nitration bacteria is performed by performing polymerization reaction in such a state that flocculated bacteria are mixed in a solution containing an acrylamide monomer, a crosslinking agent, a polymerization promoter and a polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wastewater treatment agent with high nitrification activity for microbiologically nitrifying nitrogen compounds in wastewater, and a method for producing the same.

Conventionally, nitrifying bacteria (Nitrosomonas, N1trobacterium) have been used to nitrify nitrogen compounds in wastewater.
The floating activated lr:i mud method, in which flocs of (r, etc.) are suspended in an aeration tank, or the contact aeration method, rotating disk method, watering r bed method, etc., using nitrifying bacteria in the form of a membrane, have been carried out. ing. In this method, the nitrifying bacteria come into direct contact with the wastewater, so the nitrifying bacteria are eaten by large organisms in the wastewater, such as threadworms, whorls, and ringworms, which feed on bacteria, resulting in nitrification. It had the disadvantage that the amount of bacteria decreased and that nitrogen compounds in the ammonia state could not be stably oxidized for a long period of time.

Recently, wastewater treatment agents have been proposed in which various bacteria are entrappingly immobilized in gels such as polyacrylamide, carrageenan, and alginic acid. With these treatment agents in which bacteria are immobilized in gel, the disadvantage that bacteria are eaten by relatively large microorganisms is overcome, but the activity of the immobilized bacteria decreases and when used for long-term wastewater treatment. Durability becomes an issue. When using less toxic substances that exist in nature such as carrageenan and alginic acid as a gel, the activity of immobilized bacteria can be reduced □
Although the damage is slight, the physical strength is low and there are problems with durability. On the other hand, when polyacrylamide gel is used, it has high physical strength and good durability, but the acrylamide monomer used for immobilization, the crosslinking agent,
Since the polymerization initiator and the like do not have a toxic effect on bacteria, there is a drawback that the activity tends to decrease.

In particular, nitrifying bacteria have a slow growth rate and are sensitive to toxic substances, so their activity is significantly reduced. Therefore, a wastewater treatment agent with high nitrification activity and high physical durability is desired.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to prevent the reduction of nitrifying bacteria due to feeding by relatively large microorganisms.
It is an object of the present invention to provide a wastewater treatment agent with high nitrification activity and high physical strength, and a method for producing the same. achieved.

That is, the wastewater treatment agent of the present invention is characterized in that it is formed by entrapping and immobilizing the aggregates obtained by agglomerating Mo. 11 bacteria into flocs using an organic polymer flocculant inside a polyacrylamide gel. .

The organic polymer flocculant used in the present invention may be cationic, anionic, or nonionic. Examples of the cationic polymer flocculant include polyvinylpyridine hydrochloride, polyethyleneimine, and the like. Examples of anionic polymer flocculants include storium polyacrylate, maleic acid copolymer salts, polyacrylamide partial hydrolyzate salts, and examples of nonionic polymer flocculants include polyacrylamide and polyacrylamide. Examples include oxyethylene.

Nitrifying bacteria were flocculated using a flocculant as described above, and 100
A floc-like aggregate with a size of μm11 or more is prepared, and then entrapping immobilized on polyacrylamide gel Vold i1-.

61! In order to fix or otherwise damage aggregates of J-forming bacteria, the aggregates are mixed with a solution containing acrylamide monomer, a crosslinking agent, a polymerization accelerator, a polymerization initiator, etc., and a polymerization reaction is carried out. As a crosslinking agent for acrylamide, N,N"-methylenebisacrylamide, N,N'-propylenebisacrylamide, diacrylamide dimethyl ether, 1,2-diacrylamide ethylene glycol, or N,N'-diallyltartaric acid diamide, etc. are used. As a polymerization accelerator, "C" is β-dimethylaminopropionitrile, N
, N, N', N'-tetramethylethylenediamine, etc. can be used. Moreover, as a polymerization initiator, potassium belloxonisulfate is usually used.

The gel obtained by polymerization is shaped into a sphere, cylinder, plate, fiber, hollow fiber, etc. having a size of 2 to 4 I.

When flocs of nitrifying bacteria are prepared in advance in this way and then mixed with an acrylamide polymerization solution and polymerized, they exhibit high nitrification activity over a long period of time, have excellent strength and odor, and have a long lifespan. This is because the polymer flocculant used envelops the nitrifying bacteria, and as a result, during the polymerization reaction, the toxicity of the acrylamide monomer and polymerization initiator is removed from the flocs. This is thought to be because the rate at which nitrifying bacteria are killed is significantly reduced because they do not penetrate into the interior of the nitrifying bacteria.

Furthermore, the wastewater treatment agent according to the present invention protects the nitrifying bacteria from being eaten by relatively large microorganisms and has excellent physical durability, so it exhibits high nitrification activity over a long period of time.

Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Example 1 Secondary treated water (N Ha-N15) obtained by treating sewage with activated sludge
~30 .mu./l) was used as raw water, and nitrifying bacteria that had been acclimatized for a residence time of 6 hours were used. This bacteria has a bacterial cell concentration of 40,000 mg/
Then, a polymer flocculant press (L444K, manufactured by New Metals En-1 Chemical Co., Ltd.) was added at 0.5% based on the dry weight of the bacterial cells to form flocculated bacteria. Separately, a solution containing 32% acrylamide monomer and 2% N,N'-methylenehis-acrylamide was prepared, and this solution and the flocculant suspension were mixed in the same volume ratio, and then β-dimethylaminopropylene was used as a polymerization accelerator. Pionitrile was added at a concentration of 0.5%, and potassium belloxonisulfate was further added as a polymerization initiator at a concentration of 0.25% to entrap and immobilize the flocculated bacteria. The polyacrylamide gel containing the entrapping and immobilized aggregated bacteria was molded into a cylinder with a diameter of 3 mm and a height of 3 mm.

The wastewater treatment agent thus obtained was filled into the aeration tank shown in FIG. 1 at a filling rate of 35%. The aeration tank 1 shown in Figure 1 is the riser pipe 2.
and a downcomer pipe 3, wastewater is injected from a wastewater outlet 4 and flows out from a treated water outlet 5. Air is sent from the air supply pipe 6, and the bubbles rise through the riser pipe 2, causing the wastewater treatment agent to flow due to the air lift effect, and come into contact with the wastewater to nitrify ammonia nitrogen compounds. NH4-Nl 5~30+n
g/1. (The results of treating D wastewater with a residence time of 6 hours are shown at 7 in Figure 2.

For comparison, as a conventional method, the bacterial cell concentration was 20001■/l.
The same wastewater as the one described above was treated by the floating activated sludge method, and the results are shown at 8 in Figure 2.

In addition, in FIG. 2, 9 indicates the N114-N concentration of the raw water.

As can be seen from Figure 2, in the conventional method, a large number of threadworms appeared after 20 days of operation, the amount of nitrifying bacteria decreased, and the quality of the treated water deteriorated. On the other hand, when the wastewater treatment agent of the present invention was used, even if threadworms were generated in the wastewater, the quality of the treated water was stable and -C was good.

Example 2 A floc of nitrifying bacteria was made in the same manner as in Example 1, but the flocs with different diameters were packed in various ways, and each was fixed in a package in the same manner as in Example 1 to form a cylinder with a diameter of 3++i and a length of 3 am. The activity of nitrifying bacteria in the obtained wastewater treatment agent was determined by II.
The results are shown in Figure 3.

The activity of nitrifying bacteria is determined by the oxygen uptake rate ry (mgo 2 /
h). The residual rate of activity is the ratio of γ of nitrifying bacteria before entrapping fixation to γ of nitrifying bacteria after entrapping fixation.

As is clear from Fig. 3, the residual activity of the wastewater treatment agent in which nitrifying bacteria with a floc diameter of less than 100 μm (without addition of 100% polymer a-collecting agent) was immobilized was less than 10%;
The residual activity of the wastewater treatment agent to which a polymer flocculant was added and flocculated bacteria with a floc diameter of 100 μrn or more was immobilized was 15 to 40%, and the activity was significantly improved.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the aeration tank used in the example of the present invention, Figure 2 is a diagram of the concentration of ammonia nitrogen compounds in the wastewater and treated water in Example 1 over time, and Figure 3 is the floc diameter. FIG. 2 is a relationship diagram between the residual rate of nitrifying bacteria activity and the residual rate of nitrifying bacteria activity. 2... Ascending pipe, 3... Descending pipe, 6... Air supply pipe, 7
... N II 4- of water treated with the wastewater treatment agent of the present invention
' N 1iFj I! Special HT1 Applicant: Hitachi Brandt Construction Co., Ltd. Figure 1 0 10 20 30 40 50 Number of covers@B (Japanese) Figure 3) N7r37Rino1P (,//)

Claims (3)

[Claims] (1) In a wastewater treatment agent that microbiologically nitrates nitrogen compounds in wastewater, an organic polymer flocculant is used to flocculate nitrifying bacteria into flocs, and the resulting flocs are entrapping and immobilized inside a polyacrylamide gel. A wastewater treatment agent characterized by comprising: (2) A method for producing a wastewater treatment agent, which comprises aggregating nitrifying bacteria into flocs using an organic polymer flocculant and entrapping and immobilizing the resulting flocs inside a polyacrylamide gel. (3) The method according to claim 2, in which aggregates of nitrifying bacteria are aggregated into flocs with a size of 100 μm or more.