JPH08168796A - Aerobic nitrating denitrification process - Google Patents

Abstract

PURPOSE: To simplify a process constitution, the operation facilitate and also efficiently perform nitrating/denitrification of sewage by placing alternately an aerobic stage and an anaerobic stage in multistage at the time of aerobically nitrating/denitrifying biologically an org. sewage containing a reducing type sulfur. CONSTITUTION: At first, waste water 1 is introduced into a hydrogen fermentation tank 2, where org. matters are decomposed at the time of treating a sulfur and ammonia-containing waste water such as night soil. Then, a fermented nitrated liq. 21 is introduced into an aerobic tank 3, and also a hydrogen sulfide 11 obtained by washing and desulfuring 10 a generated gas 9 is introduced into a selection tank 4 to control a concn. of total reducing type sulfur in the fermented nitrated liq. At this time, a tank in which aerobic tank/selection tank are made to be one unit are arranged in multi-stages (3, 5)/(4, 6) at an aerobic nitrating denitrification process. In the last selection tank 6, is a mixed gas 13 of a gaseous hydrogen and a gaseous CO2 is introduced by using a blower 14. Then, an efluent from the last selection tank 6 is introduced into a solid-liq. separation process 7 and this denitrifed water is discharged to outside, and also a concentrated fungus body is returned to the aerobic tank 3 as a return sludge 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aerobic nitrification and denitrification of wastewater and / or sludge, and particularly to aerobic nitrification denitrification of various kinds of wastewater and sludge containing a large amount of organic compounds such as reduced sulfur and lower fatty acids. Regarding how to nitrogen.

[0002]

2. Description of the Related Art Recently, in order to solve the eutrophication of water bodies such as rivers and seas, the removal of nitrogen by the synergistic action of hydrogen-producing bacteria and hydrogen-utilizing bacteria and the removal of phosphorus by chemical methods have been recently carried out. It is being researched and developed, and has achieved results that deserve evaluation for the removal of nitrogen (nitrate). However, these treatment technologies are limited to the removal of nitrogen in diluted water, and there is no mention of effective utilization, treatment and disposal of bottom mud having a high eutrophication potential, It has only a symptomatic effect. In addition, since the beginning of 1965, the biological nitrification and denitrification method has been researched, developed and commercialized as a source countermeasure, and in the 1950s, it was mainly applied to human waste treatment plants where nitrogen and phosphorus loads were extremely large. Has achieved concrete results that can withstand the evaluation.

However, the conventional biological denitrification method has the following technical problems, and further improvement is required as a countermeasure against the source. Since organic sewage and sludge, which are important resources as an energy source, are used as hydrogen donors for denitrifying bacteria, valuable energy cannot be recovered from rich organic substances. In the biological denitrification method, it is necessary to grow nitrifying bacteria and denitrifying bacteria having completely different physiological characteristics and functions in the process without delay, and to exert their functions. The condition setting range is narrow.

[0004]

SUMMARY OF THE INVENTION In view of the above prior art, the present invention provides an aerobic nitrification and denitrification method which has a simple process structure, is easy to operate, and is capable of efficiently nitrifying and denitrifying sewage or sludge. Is an issue.

[0005]

In order to solve the above problems, the present invention provides a method for biologically aerobic nitrifying and denitrifying organic sewage or sludge containing reduced sulfur in an aerobic process and anaerobic process. By alternately arranging the steps in multiple stages, nitrification and denitrification are carried out by sequentially passing organic sewage or sludge to each of the steps under the control of heterotrophic nitrifying and denitrifying bacteria belonging to sulfur-oxidizing bacteria. . In each of the steps arranged in the above multistage, from the aerobic step arranged in the subsequent stage to the aerobic step arranged in the preceding stage, and / or from the anaerobic step arranged in the latter stage to the anaerobic step arranged in the preceding stage It is preferable to circulate and return the in-process liquid in each process, and to arrange an aerobic process in the final stage and circulate the effluent from the process to all the aerobic processes in the preceding stage.

In the present invention, when biologically aerobic nitrifying and denitrifying organic sewage or sludge containing no reduced sulfur, the following (a) and (b), or (a) to (a)-
This is an aerobic nitrification and denitrification method in which the step (c) is performed. (A) A hydrogen fermentation step of contacting hydrogen-producing bacteria and sulfate-reducing bacteria with organic wastewater or sludge. (B) The reduced sulfur of step (a) is sequentially added to the aerobic / anaerobic step in which heterotrophic nitrifying and denitrifying bacteria belonging to a sulfur-oxidizing bacterium are arranged in multiple stages by alternately arranging aerobic and anaerobic steps. Nitrification and denitrification step of performing nitrification and denitrification through the effluent containing A hydrogen reduction step of supplying a hydrogen-containing gas to at least the nitrification-processed treatment liquid in steps (c) and (b) to completely denitrify the nitrogen oxides remaining in the treatment liquid. In the hydrogen fermentation step (a), it is preferable to wash the gas generated from the step with water and to introduce the washing effluent containing reduced sulfur into the nitrification and denitrification step (b), in which case the effluent of the step is If it is the initial stage, it can be introduced into either the aerobic process or the anaerobic process, or both.

In the nitrification and denitrification step (b), the aerobic step arranged in the latter stage is changed to the aerobic step arranged in the former stage and / or the anaerobic step arranged in the latter stage is arranged in the former stage. It is preferable to circulate and return the in-process liquid to the anaerobic process described above, and it is preferable to perform the hydrogen reduction process (c) in the final anaerobic process of the nitrification denitrification process (b). Furthermore, solid-liquid separation may be performed between the hydrogen fermentation step (a) and the nitrification denitrification step (b). in this way,
The present invention is a heterotrophic nitrifying and denitrifying bacterium, thiosphaera
Mechanism of dominant growth of bacterial group represented by Pantotropha (hereinafter referred to as Tsa bacterium) and skillfully recycling products of the post-treatment process for condition formation to promote dominant growth of Tsa bacterium To do.

Next, the present invention will be described in detail according to each step. First, the hydrogen fermentation step used in the present invention will be described. In this step, surplus electrons generated in the microbial cells in the process of decomposing organic substances are released to the outside of the microbial cells as hydrogen gas together with carbon dioxide gas. In addition, autotrophic sulfate-reducing bacteria generally live in these wastewaters and sludges, and biologically reduce the sulfates dissolved in the wastewater to reduce sulfur (S ^2- ). At the same time, carbon dioxide and water are generated. In the present invention, this reduced sulfur is effectively utilized as an energy source for heterotrophic nitrifying and denitrifying bacteria in the subsequent nitrifying and denitrifying step. In addition, not only hydrogen-producing bacteria but also various anaerobic bacteria-based mixed culture systems are constructed in human waste or sewage sludge. Depending on the culture conditions of the heterotrophic hydrogen-producing bacterium, the methane bacterium may become a dominant species in the mixed culture system, and the hydrogen production originally intended by the present invention may be inhibited.

However, in this methane bacterium and the hydrogen-producing bacterium,
There is a considerable disparity in the conditions necessary for each living and growing in the natural environment, and by artificially controlling the disparity in these conditions, the hydrogen-producing bacteria of the present invention are mixed and cultured. Among them, it can always be propagated as a dominant species. The simplest method is to utilize the fact that the growth rate of hydrogen-producing bacteria is considerably higher than that of methane bacteria, and the volume of the hydrogen fermentation tank is set so that By setting the volume to about 5 days or less, hydrogen-producing bacteria can be easily dominated (the optimum growth rate for methane bacteria is 7.8, specific growth rate μ = 0.3).
~ 0.5 day ^-1 , hydrogen-producing bacteria have an optimum pH of 5.5-5.
8, specific growth rate μ = 5 to 15 day ⁻¹ ).

As a more reliable method, the method described in detail in Japanese Patent Application No. 5-195329 previously filed by the present inventor can be applied. That is, there is a considerable difference between the two bacterial species in the redox potential suitable for growth as described below. Methane bacterium: −350 to −450 mV, hydrogen producing bacterium: −100 to −200 mV, therefore, in a continuous culture system, about −250 of this redox potential.
In order to maintain a stable mV disparity at all times, by slowly aerating the culture solution in the hydrogen fermenter to maintain a slightly anaerobic atmosphere, the target hydrogen-producing bacterium can always be the dominant species. I can. In addition, not only the heterotrophic nitrifying and denitrifying bacteria of the method of the present invention but also other autotrophs are naturally contained in the hydrogen-fermented digestive juice of human sewage containing a large amount of lower fatty acids such as acetate, ammonia, and reduced sulfur. Since nitrifying nitrifying bacteria and heterotrophic denitrifying bacteria coexist in the wild, thiosphaera pantotropha (Thio
Heterotrophic nitrifying and denitrifying bacteria useful in the present invention, such as sphaera pantotropha), cannot be the dominant species in this biological reaction system, and it is difficult to perform stable and highly efficient nitrifying and denitrifying. Becomes

As shown in FIG. 1, the nitrifying and denitrifying step, which is the central part of the present invention, has an aerobic tank for performing an aerobic step and a selective tank for performing an anaerobic step as one unit. The process configuration is connected in series, and further, means for circulating and returning the mixed culture solution of each tank to the aerobic tank in the latter stage, the aerobic tank in the former stage, and the aerobic tank in the former stage is sent. The aerobic tank was adjusted by a slow aeration with a blower so that the dissolved oxygen concentration of the mixed culture was preferably 1 mg / l or less in the dynamic state, while the selective tank did not supply air. This is a so-called simple anaerobic tank, and a stirring means is provided so that the substrate and sludge (bacteria) can be sufficiently mixed. By the arrangement and means of such a tank, the above-mentioned heterotrophic nitrifying and aerobic denitrifying bacteria (hereinafter,
Heterotrophic nitrifying and denitrifying bacterium), Thiosphaera pantotropha, has always become the dominant species in the aerobic nitrifying and denitrifying process, and a single species is successfully performing nitrification in an aerobic environment.
Denitrification is performed.

The present invention relates to the heterotrophic nitrifying and denitrifying bacterium, Thiosphaera pa.
Bacterial group represented by ntotropha (hereinafter abbreviated as Tsa bacterium), autotrophic nitrifying bacterium (mainly Nitrosomonas (Ni
trosomonas) and heterotrophic denitrifying bacteria (mainly Pseudomonas) and Paracoccus (Para).
The present invention has been accomplished as a result of fully considering the difference in physiological and functional properties of the genus Coccus. An important feature of the present invention is that, in the gas generated from the hydrogen fermenter in the first step, that is, hydrogen sulfide, a mixed gas of hydrogen and carbon dioxide, hydrogen sulfide is generated in the second step (aerobic nitrification denitrification as described above). Process)) as a hydrogen donor or growth inhibitor (for heterotrophic nitrifying bacteria and autotrophic nitrifying bacteria) in the aerobic tank and / or selective tank in the first stage,
A part of hydrogen and carbon dioxide gas washed and purified as energy is introduced into the final selection tank (anaerobic hydrogen reduction tank) which is the third step, and a hydrogen donor of heterotrophic nitrifying and denitrifying bacteria (Tsa bacteria). In addition, it is to completely denitrify the residual oxidized nitrogen, mainly nitrite, by supplying it as a carbon source, and dissipate it into the atmosphere.

Next, the features of the constitution and the role of the nitrifying and denitrifying step of the present invention will be described. The pH of the mixed culture solution is set to 8.0 to 8.5. This aims to suppress the growth of autotrophic nitrifying bacteria and enhance the growth of Tsa bacteria by utilizing the difference in the optimum pH range. In addition, when the target of treatment is human waste, it is not necessary to adjust the pH as long as Thiosphaera pantotropha is the dominant species. The dissolved oxygen concentration of the mixed culture is 1 mg / l or less. This aims to suppress the growth of autotrophic nitrifying bacteria and enhance the nitrifying and denitrifying abilities of Tsa bacteria by utilizing the difference in oxygen requirement.

Further, in addition to the above-mentioned constitution, it is desirable to carry out the following operations in order to optimize the environment in which the Tsa bacteria grow. Injection of reduced sulfur in the evolved gas into the aerobic tank and / or selective tank in the frontal region. This is intended to inhibit the growth of autotrophic nitrifying bacteria, heterotrophic denitrifying bacteria, and increase the growth of Tsa bacteria. Circulation of mixed culture solution from the rear aerobic tank to the front aerobic tank
Return. This is intended to promote the growth of Tsa bacteria and inhibit the growth of heterotrophic denitrifying bacteria. Usually, when acetate and ammonia are present as substrates and the dissolved oxygen concentration is high, if the substrate concentration of the aerobic tank inflow water is high in the mixed culture system of Tsa bacteria and other heterotrophic denitrifying bacteria, Tsa The growth rate of the bacterium becomes larger than that of the heterotrophic denitrifying bacterium, and the Tsa bacterium becomes the dominant species in the mixed culture system.

However, when the substrate conditions are the same and the dissolved oxygen concentration is intentionally adjusted to be low as in the present invention, there is no competitive relationship between the two as described above, and the Tsa bacteria can be used at any substrate concentration. It grows faster than heterotrophic denitrifying bacteria and is always the dominant species. Therefore, the circulation of the aerobic mixed culture solution of the present invention to the former stage is performed by diluting the aerobic tank inflow water with the treated water of the latter stage in consideration of the instability of artificially controlling the dissolved oxygen concentration. It is designed so that the bacteria will always be the dominant species even if there are some changes in conditions. Furthermore, by circulating the aerobic mixed culture solution in which the Tsa bacteria have become the dominant species, the competitive relationship between the Tsa bacteria and the heterotrophic denitrifying bacteria in the selection tank and the mutual bacterial count relationship are Ts.
It is extremely advantageous for the bacterium a and can reliably suppress the growth of the heterotrophic denitrifying bacterium. Heterotrophic denitrifying bacteria can grow by oxygen respiration in an environment where oxygen is present, but in an aerobic tank where Tsa bacteria are the dominant species, competition for oxygen uptake cannot be a winner. Growth inhibition is further increased.

Multi-stage aerobic / selective tank process configuration. This is intended to suppress the growth of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria and to increase the growth of Tsa bacteria. When the organic substrate is mainly a lower fatty acid, the saturation constant for oxygen of Tsa bacteria is considerably smaller than the saturation constant for oxygen when ammonia of autotrophic bacteria is used as a substrate. This means that in a competitive relationship between the two, under the condition that the aerobic tank is operated at a low dissolved oxygen concentration as in the present invention, the autotrophic nitrifying bacteria cannot compete with Tsa bacteria in the competition of oxygen uptake in the aerobic tank, Oxygen respiration is restricted and proliferation is significantly suppressed. By repeating this environmental condition in multiple stages, the growth inhibition of autotrophic nitrifying bacteria is strengthened and cannot be the dominant species in the process of the present invention.

Since Tsa bacteria can utilize nitrous acid and nitric acid produced by autotrophic nitrifying bacteria by the oxidation of ammonia as electron acceptors, there is essentially no competitive relationship between the two for ammonia. Although it does not exist, it is considered that the competitive relationship between Tsa bacteria and autotrophic nitrifying bacteria is not completely established by repeating this environmental condition in multiple stages. In a mixed culture system of Tsa bacteria and heterotrophic denitrifying bacteria, when the living environment of aerobic environment of 4 to 5 hours and anaerobic environment of 2 to 4 hours is repeated, Tsa bacteria become responsive to this environmental change. Although excellent, the growth of the heterotrophic denitrifying bacterium is remarkably suppressed, and the Tsa bacterium is always the dominant species in the competitive relationship between the two.

The reason is as follows. -Oxygen contamination (retention in aerobic tanks) of heterotrophic denitrifying bacteria reliably inhibits nitrate reductase and / or nitrite reductase biosynthesis and / or induction. -When the organic substrate is mainly lower fatty acid, the saturation constant of Tsa bacteria for acetate is considerably lower than that of the heterotrophic denitrifying bacteria. Bacteria do not compete with Tsa in substrate competition and therefore cannot be the dominant species. Furthermore, when an aerobic / anaerobic environment is repeated in a mixed culture system of Tsa bacteria and heterotrophic denitrifying bacteria, high concentration of nitrite is accumulated in the mixed culture solution, resulting in oxygen uptake of heterotrophic denitrifying bacteria. Are blocked, and electrons are accumulated in the electron transfer system, resulting in a reduced state. Therefore, more electrons are transferred to nitric acid, and as a result, more nitrite is produced, the electron transfer system of the heterotrophic denitrifying bacterium does not operate normally, and extreme growth inhibition occurs (Tsa). It is convenient because the end point of fungal nitrification is nitrite).

Circulation / return of the mixed culture solution from the latter-stage selection tank to the former-stage selection tank. This is intended to suppress the growth of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria. Multi-stage aerobic tank described above /
This is a means to further promote the effect of the selective tank (anaerobic tank), and by repeating the aerobic / anaerobic atmosphere several times, the growth of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria is strengthened. This is aimed at suppressing the effect. As a result, the growth of Tsa bacteria is promoted. In this way, nitrite reduction (denitrification) with hydrogen gas in the final selection tank is smoothly performed, and complete denitrification is achieved.
In the present invention, it is also possible to directly nitrify and denitrify undiluted urine having a high pollutant concentration as it is without providing a hydrogen fermentation step.

As is well known, undiluted urine has a lower fatty acid concentration of 3,500 to 4,500 mg / min as a pollutant.
1, the concentration of ammonia is 3,000 to 4,000 mg /
Even if the concentration is fairly high as 1, the growth rate of Tsa bacteria is high even when the dissolved oxygen concentration of the mixed culture is high in the process of the present invention and / or when it is as low as about 1 mg / l. It is higher than the rate, and basically, the Tsa bacterium becomes the dominant species in the competitive relationship between the two under the above conditions, but when the concentration of lower fatty acid and ammonia flowing into the first stage aerobic tank is dilute, the Tsa bacterium is It is perfect to make sure it is the dominant species. To this end, in the present invention, a means for additionally providing an aerobic tank, particularly at the final stage, and circulating and returning an appropriate amount of the aerobic mixed culture solution to the aerobic tank at each stage in the front part is provided.

In addition to the above, the following effects can be expected from the installation of this final aerobic tank. By circulating and returning the mixed culture solution of the final stage, which has the highest concentration of Tsa bacteria, to the aerobic tank of the previous stage, especially the aerobic tank of the forefront, via the multi-stage aerobic tank / selection tank , Tsa bacteria can be relieved from excessive load due to a rich substrate. For Tsa bacteria, the frequency of passing through an environment suitable for growth is increased, whereas the frequency of passing through an environment unfavorable for heterotrophic denitrifying bacteria is increased. The competition of the bacterial species becomes a significant advantage for the Tsa bacteria, and it is possible to ensure that the mixed culture system of the process of the present invention can produce Ts
Fungus a can be the dominant species. Dissolved oxygen is provided to the final effluent of the process of the invention, reducing the load on the external water system.

Next, the hydrogen reduction step of the present invention will be described. Some heterotrophic denitrifying bacteria can use hydrogen gas directly as a hydrogen donor, but its capacity is significantly weaker. On the other hand, Tsa bacteria can strongly denitrify (both nitrate and nitrite) by using gaseous hydrogen as an energy source. Heterotrophic nitrification by Tsa is NH
^{_{4 + → NH 2 OH → NO}} 2 - oxidation pathway is the end point of,
Unlike normal autotrophic nitrifying bacteria, it does not pass through NO ₃ ⁻ .
Therefore, since denitrification starts from NO ₂ ⁻ , the amount of hydrogen donor required is small, which is economical, but when the wastewater itself contains nitrates from the beginning, it is aerobic. It has the function of denitrifying.

The biological denitrification reaction in the case of using pure hydrogen as the hydrogen donor is as follows for nitrate and nitrite. - nitrate ^{_{(breathing) 2NO 3 - +5 (H 2}} ) = N 2 + 2OH - + 4H 2 O · nitrite ^{_{(breathing) 2NO 2 - + +3 (H}} 2) = N 2 2OH - + in 2H ₂ O aerobic nitrification denitrification step It may be difficult to supply stoichiometrically the reduced sulfur, lower fatty acid and hydrogen sulfide corresponding to the amount of nitrite to the hydrogen-fermented digestive fluid, and it may be difficult to operate. Depending on N
Not necessarily hydrogen donor amount of the is present in excess with respect to O _x amount.

In the method of the present invention, this technical problem is solved on the safety side by using a part of a large amount of hydrogen gas generated in the hydrogen fermenter in a divided manner. Can be effectively used as clean energy. Also, when the generated hydrogen is supplied to the aerobic tank of the aerobic nitrification and denitrification process together with air as a hydrogen donor, oxygen and hydrogen will be mixed, and the hydrogen content of the mixed gas will change to air. On the other hand, if it exceeds 4%, there is a risk of inducing an explosion. The method of the present invention completely solves this problem by feeding it to the final selection tank, which is aimed at finishing the NO _x removal in the final stage.
The above is the means and method for solving the problems and objects of the method of the present invention, whereby the production of hydrogen energy and the removal of NO _x from the organic wastewater containing sulfide and ammonia, which is the object of the present invention, are completed. Will be achieved.

Thiosphaer pantotroph, which is the dominant species in the aerobic nitrification and denitrification step of the method of the present invention
a pantotropha) is a glycolytic system and TCA in the process of organic matter decomposition.
The electrons emitted from the cycle are transported to oxygen through an electron transport system composed of cytochromes.
Unlike other bacteria, self-regulation of cytochrome aa ₃ and cytochrome O existing at specific sites in the electron transfer system creates an oxidative atmosphere and a reducing atmosphere in the metabolic pathway inside the cell simultaneously, which is favorable. It is a special bacterium that has the function of simultaneously performing heterotrophic nitrification and aerobic denitrification under aerobic conditions. In addition, Tsa bacteria can biosynthesize and induce various enzymes accurately in response to external conditions,
In addition, it is a multifunctional bacterium that can grow autotrophically, heterotrophically, or mixedly, and can withstand rapid changes in the quality and quantity of electron acceptors and grow. The present inventor has learned that bacteria having this special physiological property / function generally inhabit ordinary soil or a mixed culture system of the current biological denitrification process. As a result of various studies on the conditions for making P. dominant a dominant species, the aerobic nitrification and denitrification method of the present invention has been established. Of course, in the practice of the present invention, preserved bacteria of strains belonging to Tsa may be used.

[0026]

Next, the excellent function of the present invention will be described with reference to FIG. 1 showing an example of the present invention. In addition, in explaining the functions and effects of the present invention, assuming a human waste treatment plant where the usual biological nitrification and denitrification method is most frequently used at present, human waste was selected as a substrate. The present invention is not limited to the above, but is also applied to organic wastewater and organic wastewater containing sulfide and ammonia in a concentrated manner. The biological nitrification denitrification method as a conventional method depends on the hydrogen donor required for the reduction of nitrate and nitrite and relies on the organic matter (BOD) of the urine itself, so that it has a high potential for energy production. Human waste, an inherent valuable resource, is wasted for the purpose of denitrification. In the present invention, without wasting this valuable resource, first, hydrogen, which is clean energy, is taken out by a hydrogen-producing bacterium, and is used as a hydrogen donor for denitrification, and the reduction contained in human sewage and / or its fermentation digested liquid Type sulfur,
By using various lower fatty acids and hydrogen sulfide in the generated gas as a hydrogen donor to grow heterotrophic nitrifying and denitrifying bacteria having a function of reducing and removing NO _x as a dominant species under specific culture conditions, It is possible to simultaneously achieve the objectives of energy production and denitrification from human waste. However, in the present invention, the hydrogen fermentation step is not provided, and only the aerobic nitrification and denitrification step in which the total amount of the organic matter in human waste is effectively utilized as a hydrogen donor for heterotrophic nitrification and aerobic denitrification can be performed.

Referring to FIG. 1, first, a case where human waste is used as the sulfur-containing and ammonia-containing wastewater 1 will be described. The human sewage is transferred to the hydrogen fermentation tank 2 continuously or intermittently without being diluted.
The hydrogen fermenter 2 decomposes the organic matter of human waste, but the main players of hydrogen production play the following bacteria that are commonly inhabited in human waste or soil. One bacterium or a mixed culture system may be cultivated in an increased amount to inoculate the hydrogen fermenter 2 in an appropriate amount, or alternatively, it may be used by being dispensed from a public microbial preservation institution. It is recommended to grow a hydrogen-producing bacterium that is wildly inhabited as a dominant species under specific culture conditions and use it. Clostridium genus Enterobacter genus Ruminococcus genus Bifidobacterium genus

These hydrogen-producing bacteria, human waste (organic matter),
It decomposes into lower fatty acid, hydrogen gas and carbon dioxide gas under the following conditions. Optimum pH: 5.5 to 5.8, Optimum temperature: 25 to 30 ° C., Fermentation days: 5 to 7 days, Specific growth rate: 5 to 15 days ⁻¹ , Organic matter decomposition (C ₆ H ₁₀ O ₅ ). n → 4C ₆ H ₁₂ O ₆ = 3CH ₃ (CH ₂ ) ₂ COOH + 2CH ₃ COOH + 8H ₂ + 8CO ₂ (1) 3CH ₃ (CH ₂ ) ₂ COO ⁻ + 6H ₂ O = 6CH ₃ COO ⁻ + 3H ⁺ + 6H ₂ (2) 2CH ₃ COO ⁻ + 4H ₂ O = 10H ⁺ + 2H ₂ + 4CO ₂ (3)

On the other hand, the biological reaction of the formula (1) is basically the main reaction, and a large amount of lower fatty acids (mainly butyric acid, acetic acid, lactic acid, etc.) and equimolar hydrogen gas and carbonic acid are produced by microbial decomposition of human waste. Gas is produced. As described above, the hydrogen production reaction by the hydrogen-producing bacterium is the sucking ergon reaction.
Since the energy derived from TP is insufficient, a dynamic equilibrium is reached when the lower fatty acid is considerably accumulated, and the hydrogen generation reaction does not easily proceed further. Therefore, in the hydrogen fermentation by the conventional method, the conversion efficiency of hydrogen atoms in organic matter to hydrogen gas is low, and there is a problem in economic efficiency. Therefore, in the present invention, in order to improve the hydrogen conversion rate in the organic matter to the extent possible, the following slightly anaerobic hydrogen fermentation method (see Japanese Patent Application No. 5-195329) is preferably adopted. That is, hydrogen is forcibly removed from the biological reaction system to outside the system (vacuum fermentation), and at the same time, the redox potential of the solution in the hydrogen fermentation tank 2 is artificially changed from -100 to -200 m.
70% to 80% of hydrogen gas generation by setting V
Can be increased to the extent.

Human waste 1 has a considerable regional characteristic, and its physicochemical properties have a considerable range, but sulfate ion is usually 5
The amount of sulfur ions derived from sulfur-containing protein is 100 to 200 mg / l. Of these, sulfate ions are reduced to almost 100% sulfur ions by the sulfate-reducing bacteria coexisting in the mixed culture solution during the hydrogen fermentation process by the heterotrophic hydrogen-producing bacterium in the hydrogen fermentation tank 2, and the fermentation digestion solution 21 And / or present as hydrogen sulfide in the evolved gas 9. Further, the sulfur content in the sulfur-containing protein behaves in a substantially similar manner and is distributed to the fermentation digestion liquid or the generated gas 9. The fermented digested liquid 21 after the hydrogen fermentation is introduced into the aerobic tank 3 in the first stage of the next aerobic nitrification and denitrification process. The reduced sulfur contained in the fermented digested liquid 21 naturally flows into this tank 3, and hydrogen sulfide 11 obtained by washing and desulfurizing the generated gas 9 with water 10 is introduced together with the selective tank 4, and The concentration of total reduced sulfur is approximately 250 to 350 mg / l.

The fermented digestion liquid 21 contains about 1,500 of various lower fatty acids by hydrogen fermentation using organic matter as a substrate.
~ 2,000 mg / l (up to about 3,000 mg / l)
, Both of which are mainly used as hydrogen donors for nitrite reduction in a mixed culture system in which Thiosfaera pantotropha, an aerobic heterotrophic nitrifying and denitrifying bacterium, is the dominant species. It The ammoniacal nitrogen contained in the fermentation digestion liquid 21 as a result of the hydrogen fermentation of the human waste 1 normally fluctuates in the range of 1,500 to 2,000. This NH
Assuming that _4- N is 100% nitrified by the heterotrophic nitrifying and denitrifying bacterium, NO ₂ -N denitrified by 21 reduced sulfur in the fermentation digestive liquor is about ₂ % from the following stoichiometric relationship. 270
When the lower fatty acid contained in the fermentation digestive juice 21 is represented by acetic acid, NO ₂ due to the lower fatty acid
The removal concentration of -N is about 1,100 mg / l, and the absolute amount of the hydrogen donor is insufficient for completely reducing all NO ₂ -N contained in the fermentation digestion liquid 21. _{* △ H 1 = kg · S} 2- / kg · NO 2 -N = 1.42 △ H 1-1 = 0.7 * △ H 2 = kg · CH 3 COOH / kg · NO 2 -N =
2.00 ΔH ₂ ^-1 = 0.5

According to the structure guideline of the human waste treatment facility by the Ministry of Health and Welfare, the total nitrogen concentration of 4,20 is calculated as the nitrogen pollution load of human waste.
Since 0 mg / l and NH ₄ —N concentration of 3,200 mg / l are specified, the hydrogen donor is considerably insufficient with respect to this nitrogen concentration only with the reduced sulfur and the lower fatty acid. In the method of the present invention, in order to satisfy the above-mentioned essential conditions for predominantly growing Tsa bacteria, the aerobic nitrifying and denitrifying step is provided with a multi-stage aerobic / selective tank. Normally, it is enough to install two units at best when the target is human waste (aerobic tanks 3, 5 and selective tanks 4, 6), and the total volume of the aerobic nitrification and denitrification step is 5.5. 6.5Q
m ³ (... Q; treated water amount per day) is suitable. The bacterial cell concentration in this tank is approximately 10,000 to 1
6,000 mg / l is sufficient, and the volume ratio of the aerobic tank / selective tank is 1: 1 as a standard, but this volume ratio should be determined by the type (water quality) of the wastewater to be treated, Normally 1.0: 0.5 for human waste, which is the subject of the present invention.
Is appropriate.

Further, the amount of circulation and return from the aerobic tank to the aerobic tank,
Circulation return amount from selected tank to selected tank is 15-20 Qm ³ /
If it is about a day, the effect of circulation and return will surely be exhibited. In the aerobic tanks 3 and 5, when the mixed culture system in the tanks reaches a microbiologically steady state, the dissolved oxygen concentration of the mixed culture solution is preferably in a range not exceeding 1 mg / l. Slow aeration is performed while controlling the air blower 18 appropriately. In addition, the selective tanks 4 and 6 are provided with a stirring mechanism capable of performing slow stirring so that the substrate and the cultured bacterial cells in which Thiosphaera pantotropha is the dominant species come into sufficient contact with each other, and oxygen from the atmosphere is preferable. A cover may be provided to prevent the introduction of Approximately 2 by the above-mentioned components and / or means
Heterotrophic nitrifying and denitrifying bacteria became the dominant species after selective culture for 0 to 30 days. At this stage, the heterotrophic nitrification rate in the experiment using Thiosphaera pantotropha human waste as a substrate and The aerial denitrification rates were as follows, and the reaction rates comparable to those of the current biological denitrification methods combining the functions of the existing nitrifying bacteria and denitrifying bacteria were obtained. * Heterotrophic nitrification rate = 0.04 to 0.07 kg NH
_4- N / kg ・ MLSS / day * Aerobic nitrification rate = 0.07 to 0.1 kg ・ NO ₂ -N
/ Kg / MLSS / day

After passing through such steps, the treated water in the aerobic tank 5 containing the remaining NO _x -N is introduced into the selective tank 6 in the final step. By this final selection tank 5 (hydrogen reduction tank), heterotrophic nitrifying and denitrifying bacteria are overwhelmingly predominant. Into this tank 6, a mixed gas 13 of hydrogen gas and carbon dioxide gas produced by a heterotrophic hydrogen-producing bacterium in the hydrogen fermentation tank 2 is introduced by a blower 14 and is repeatedly circulated for reuse of hydrogen as a hydrogen donor. At the same time as increasing the utilization rate, it supplies carbon dioxide as an organic carbon source. The hydrogen production amount in the hydrogen fermenter 2 per organic matter decomposition amount of human waste was approximately as follows. Hydrogen production amount = 0.25 m ³ · H ₂ / kg-VS _R, where VS _R is the amount of decomposed organic substances. The amount of hydrogen required for nitrite reduction and nitrate reduction is calculated from the biological reaction formula of hydrogen reduction. Quantitatively, the following numerical values are calculated. * Amount of hydrogen required for nitrate reduction 0.9m ³ · H ₂ /
kg-NO ₃ -N * Amount of hydrogen required for nitrite reduction 0.67 m ³ · H ₂
/ Kg-NO ₂ -N

Assuming an organic matter decomposition rate of 80% in the hydrogen fermentation of night sewage based on the above basic numerical values, NO _x -N remaining in the aerobic tank 5 of the aerobic nitrification and denitrification step is about 1,000 mg / l. Hydrogen is generated in an amount of about 8 to 10 times the amount of hydrogen required for completely denitrifying hydrogen (assuming a utilization efficiency of 100%). This large excess of hydrogen 15 can be used as clean energy for multiple purposes. Effluent water was completely removed NO _x -N and organics final selection vessel 6 is introduced to solid-liquid separation step 7, denitrification treatment water 8 is discharged outside the water system, return the concentrated cells Sludge 19 as aerobic tank 3 in front of aerobic nitrification and denitrification process
It is sent back to and used repeatedly. The device applied in the solid-liquid separation step is not specified, and, for example, an ordinary gravity type sedimentation tank, a centrifugal separator, or various separation membranes can be used. Further, the biological treatment method of the aerobic nitrification denitrification step, which is the central part of the denitrification treatment, is not particularly limited to the floating type biological treatment, and various attachment media and bacterial cells are attached to the immobilization medium. The method of fixing / or fixing is also included in the present invention. When this type of biological treatment system is applied, it is not necessary to return cells 19 in particular. on the other hand,
The bacterial cells grown in the hydrogen fermentation tank 2 and the aerobic nitrification and denitrification step are taken out as excess sludge 20 and treated / disposed by an appropriate method.

[0036]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. Example 1 (a) Hydrogen Fermentation of Collected Urine by the Genus Clostridium A treatment plant was selected from which a relatively concentrated undiluted urine similar to the human waste pollutant load of the structural standard concerning the human waste treatment facility of the Ministry of Health and Welfare was selected and tested. An experiment of hydrogen fermentation of human waste was performed as a sample. The main physicochemical properties of the test urine are as shown in Table 1 (stored in a refrigerator at 5 ° C or lower).

[0037]

[Table 1] (Note) All units are shown in g / l except pH. * The ratio of loss on ignition to total solids is 75.1%. * Test urine is a sample that has been filtered through a 1 mm open screen.

The hydrogen fermenter is a cylindrical fermenter having an actual water-filled volume (effective volume) of 5 liters, which is placed in a constant temperature water bath of 30 ° C. and subjected to a medium temperature fermentation test for 5 days. I did. Initially, it was considered to inoculate a hydrogen fermenter with an appropriate inoculum, but the number of general bacteria under the anaerobic condition of test urine was about 10 ^8-9 / g · human waste, and the number of bacteria of the genus Clostridium. Since many inhabited so as to reach 10 ^{6 -7} pieces / g · human waste, no inoculation of inoculum was carried out at the start of hydrogen fermentation. The experimental conditions for hydrogen fermentation are summarized as follows. Operating conditions for hydrogen fermentation * Fermentation temperature: 30 ± 1 ° C, * pH in dynamic state during operation: 5.5-6.
0, * Fermentation days: Approximately 5 days, * Organic load: 5.26 kg · VS / m ³ · day, * Manure supply method;

Since the hydrogen fermentation tank used has a small effective volume of 5 liters and is small in scale, it is technically difficult to directly apply the mechanism of the vacuum fermentation in the present invention to the experimental apparatus. Therefore, a simplified method was used. That is, a vacuum pump is connected to a pipe made of vinyl chloride that communicates with the gas phase portion of the hydrogen fermentation tank, and the vacuum pump is operated so that the total tank becomes substantially -1,000 to -2,000 mmAq. The reduced pressure was automatically controlled, and the reduced pressure fermentation was performed. The test urine is slowly aerated before being put into the hydrogen fermenter, so that the oxidation-reduction potential (hereinafter, abbreviated as ORP) of the test urine is higher than a predetermined ORP, specifically, -50. ~-
It was adjusted to 100 mV and then charged into a hydrogen fermentation tank. ORP sensor is installed in the hydrogen fermenter,
While monitoring the RP value, the operation was carried out with a set value of -150 mV suitable for the growth of heterotrophic hydrogen-producing bacteria.

Regarding the load of organic matter on the hydrogen fermenter, about 1/3 of the final load was applied at the beginning of operation, and hydrogen-producing bacteria were grown by a method of gradually increasing the load, but after the operation was started, After about one month, the steady state was reached under the set organic load condition. The inoculation with the inoculum was not particularly performed as described above. After the experiment was completed, the hydrogen-producing bacteria in the grown sludge of this experiment were identified, and as a result, it was confirmed to be a mixed culture system of the following multiple types of heterotrophic hydrogen-producing bacteria. Detected heterotrophic hydrogen-producing bacteria * Clostridium butyric
um (ATCC 25779)) * Clostridium barkeri
(ATCC 25849)) ＊ Clostridium cel
lulolyticum (ATCC 35319)) * Clostridium dyspolicum (Clostridium dispo
ricum (ATCC 43838)) * Clostridium pro
pionicum (ATCC 25522))

From the results of this identification, it is useful for human waste itself when general pumped urine is used as a substrate for hydrogen fermentation without purchasing a pure strain from a microorganism preservation institution such as ATCC and inoculating it into a hydrogen fermenter. Hydrogen-producing bacteria, mainly the genus Clostridium, inhabit wildly, and hydrogen fermentation was carried out without resistance due to the synergistic action of these bacteria. If the conditions necessary for hydrogen fermentation are set, the growth of methane bacteria will be suppressed, the hydrogen-producing bacteria group that is most suitable for the input substrate will be constructed, and stable hydrogen fermentation will be performed rather than artificially inoculating inoculum. It was proved that The above experimental equipment,
The verification experiment under the experimental conditions was continued for 3 months after the operation reached a steady state, and Table 2 shows the average values of the treatment results obtained during about 1 month at the end of the experiment. The sample used for the water quality analysis was used as a sample for analysis by subjecting the fermented digested liquid to a centrifugal separator having a centrifugal force of 1,500 G for 10 minutes to forcibly separate and remove suspended matter containing bacterial cells.

[0042]

[Table 2] (Note) *; Unit is mg / l.

The results obtained by the hydrogen fermentation verification experiment of human waste are summarized as follows. (1) Hydrogen fermentation of human waste is slowed down by hydrogen-producing bacteria that originally live in human waste, even if they do not rely on pure strains of hydrogen-producing bacteria from public microbial preservation institutions. proceed. (2) In particular, by applying the slightly anaerobic / vacuum fermentation by the present inventor, a substantial amount of the lower fatty acid originally to be accumulated in the fermentation digestive liquid is also converted into hydrogen (energy). As a result, the generation ratio of carbon dioxide gas and hydrogen gas, which are predicted to be biostoichiometrically approximately equal, is approximately 3
It became 5:65. It is considered that this is because the hydrogen fermentation by slightly anaerobic / vacuum fermentation substantially converts the hydrogen fermentation, which is originally an absorption ergon reaction, into a generative ergon reaction. (3) Sulfate ion (720 mg /
1) is reduced to substantially 100% reduced sulfur by sulfate-reducing bacteria. The sulfur ion (S ²⁻ ) of the fermented digestive juice was 310 mg / l as an average value, which was higher than the chemical conversion value, but this was due to the sulfur of sulfur-containing protein in human waste. it is conceivable that.

(B) Aerobic nitrification and denitrification in a multistage aerobic / selective tank process by the heterotrophic nitrifying and denitrifying bacterium Thiosphaera pantotropha, and denitrification by hydrogen reduction. Here, the two-stage aerobic nitrification and denitrification tank (two-stage x aerobic tank / selection tank) shown in Fig. 1 that can be continuously processed was manufactured, and the final selection tank was used as a reduction tank with hydrogen generated by hydrogen fermentation. used. A gravity type sedimentation tank (solid-liquid separation tank) for the purpose of concentrating / separating bacterial cells, a concentrated bacterial cell return path and a gas circulation path for hydrogen reduction were manufactured, and aerobic nitrification denitrification by continuous treatment was performed. An experiment was conducted. The selection tank was provided with a stirrer for performing slow stirring, and was further provided with a cover to prevent the mixed culture solution from directly contacting the atmosphere. As for the hydrogen fermentation digestion liquid used for the nitrification and denitrification experiment, a 10-liter hydrogen fermentation tank was separately prepared, and hydrogen fermentation of urine was performed in parallel under the same conditions as the above (a), and then the (b) supply was performed. A test sample was used.

The flow sheet of the experiment is as shown in FIG. 1. The following experimental apparatus corresponding to this treatment process was assembled, and the fermentation digestion liquid was injected into the first-stage aerobic tank and the solid-liquid separation tank was used. Regarding the return of concentrated bacterial cells of, the semi-continuous type, injection into the aerobic tank / selection tank which is the first unit of hydrogen sulfide water, the mixed gas (hydrogen + carbon dioxide) to the hydrogen reduction tank (final selection tank) The circulation operated continuously. Air was continuously blown into the aerobic tanks in the first and second stages, but when the fermentation digestion liquid injection was interrupted, the air blowing rate was extremely narrowed and the dissolved oxygen concentration in the tank liquid was 1 mg. Care was taken not to exceed / l. Experimental equipment and experimental conditions * Conditions common to all treatment processes-Treatment water temperature: 30 ± 1 ° C, all experimental equipment was installed in a large constant temperature water tank and operated at the above temperature.・ Fermented digestive fluid injection volume: Q = 1 liter / day,

* Individual experimental equipment and experimental conditions * Square type aerobic nitrification and denitrification process: (aerobic tank 2 liters / selective tank 1 liter) x 2 stages, tank volume = 6Q = 6 liters, total tank volume BOD volume load for: 0.45 kg / m ³ · day, BOD sludge load for all tank sludge (bacteria): 0.045 kg / kg · day, NH ₄ -N sludge load for all tank sludge (bacteria) (Nitrification rate): 0.028 kg / kg-day, However, sludge concentration in the tank: 10,000 mg / l ★ Circulating sludge amount-Circulation amount to the second-stage aerobic tank / the first-stage aerobic tank: 10Q = 10 liters / Day: ・ Circulation amount to the latter-stage selection tank / the first-stage selection tank: 10Q = 10 liters / day,

Retention time in each tank ・ Retention time of fermentation digestion liquid in aerobic nitrification and denitrification process: 6 days ・ Retention time in each aerobic tank (including circulation volume of 10 liters): 4. 36 hours, -Retention time in each selected tank (including circulation volume of 10 liters): 2.18 hours-Retention time in all tanks (including circulation volume of 10 liters): 13 hours, but returned sludge Ignored the amount. ★ Aeration in aerobic tank ・ Continuous aeration with diffuser stirring by a small blower ・ Dissolved oxygen concentration is automatically controlled to 1 mg / l or less in conjunction with dissolved oxygen meter ★ Agitation in selection tank ・ Normal for closed selection tank A paddle type stirrer is installed to gently stir

★ Hydrogen reduction tank (final selection tank) ・ Square type closed tank: volume 1 liter ・ Mixed gas (H ₂ + CO ₂ ) circulation: continuous circulation by blower ★ Solid-liquid separation tank Gravity circular precipitation tank: volume 1 liter, concentrated sludge concentration: 15,000 to 18,000 mg / l, The above relationship is shown in a simplified manner in FIG. Table 3 shows the results of the verification experiment of aerobic nitrification and denitrification of the hydrogen fermentation digestion solution obtained by the above-described experimental apparatus and experimental conditions (average value for one month after the operation reached a steady state).

[0049]

[Table 3] (Note) *: All units are shown in mg / l except pH. *: All analytical samples are the separation liquid of the centrifuge. The extent the presence of NO ₃ -N is that you can ignore.

The results of the aerobic denitrification verification experiment by the heterotrophic nitrifying and denitrifying bacterium of the hydrogen fermentation digested liquid are summarized as follows. (1) by a multistage aerobic tank / selection bath process, circulates back to each of the mixed culture aerobic tank / anaerobic tank in front, yet the direct reduction of NO _x -N with hydrogen gas at a selected vessel in the last stage As a result of carrying out the treatment experiment under the operating condition of (b), initially, incomplete nitrification and denitrification due to autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria progressed, but about 1 month after the start of operation After the passage of time, the growth of the above-mentioned autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria was remarkably suppressed, and instead, Tsa bacteria, which are heterotrophic nitrifying and denitrifying bacteria, gradually grew in a mixed culture system. Finally, the Tsa bacteria became a complete dominant species, and as shown in Table 2, good nitrification and denitrification were performed.

(2) This heterotrophic nitrifying and denitrifying bacterium was presumed to be Thiosphaera pantotropha. Bacteria of this type have the nitrite as the final form of ammonia oxidation, which is advantageous from the viewpoint of supplying a hydrogen donor. Further, the present invention completes heterotrophic nitrification and aerobic denitrification by a kind of bacteria called heterotrophic nitrifying and denitrifying bacteria, in contrast to the conventional nitrifying and denitrifying method by the synergistic action of nitrifying and denitrifying bacteria. Process, which simplifies the process, facilitates operation management,
In addition, it can be evaluated as an extremely excellent biological nitrification and denitrification method from the viewpoint of economic effect. (3) Nitrification and denitrification functions in the aerobic nitrification and denitrification process, including hydrogen reduction in the final selection tank, are almost complete, and the final discharged water contains only 10 mg / l or less NH ₄
-N was only detected.

(4) As shown in Table 3, the process of the present invention resulted in unexpected removal of PO ₄ -P. Although I have not clarified the reason,
It is possible that the environmental change caused by the combination of aerobic tank / selective tank (anaerobic sugar) induced the growth of dephosphorization bacteria, or that the heterotrophic nitrifying and denitrifying bacteria acquired the dephosphorization function. This is an important subject for future study. (5) Mixed gas (H ₂ + C in the hydrogen reduction tank in the final step)
The nitrite nitrogen remaining in the second-stage aerobic tank effluent due to the circulation of O ₂ ) was almost completely denitrified using hydrogen as a hydrogen donor. It is considered that this denitrification process using hydrogen gas favorably acted on the heterotrophic nitrifying and denitrifying bacteria in the competitive relationship between the heterotrophic nitrifying and denitrifying bacteria. (6) In the hydrogen reduction step, even if hydrogen produced by hydrogen fermentation of human waste is consumed as a hydrogen donor of heterotrophic nitrifying and denitrifying bacteria, a large amount of hydrogen remains as an excess energy source, and as clean energy. It can be used to advantage.

(C) Effects of aerobic mixed solution circulation and selective mixed solution circulation In the aerobic nitrification and denitrification process of the present invention shown in FIG. 1, the aerobic tank mixed solution circulation and selective tank mixed solution circulation described above are performed. , In a mixed culture system in which various bacteria coexist with the heterotrophic nitrifying and denitrifying bacterium that plays the main role of the present invention, it was confirmed whether it is an essential condition to overcome the competitive relationship and become the dominant species. The experiment for doing was done. The experimental apparatus and the experimental conditions were the same as those in (b) above except that the two experiments were rigorous in comparison and the circulation of the mixed solution was excluded in order to provide objectivity. The results of this experiment are summarized in Table 4.

[0054]

[Table 4] (Note) *; All units are shown in mg / l except pH.

The experimental results for confirming the effect of the mixed solution circulation of (c) are summarized as follows. (1) As can be easily understood from the experimental results in Table 4, if the aerobic tank mixed solution circulation and the selective tank mixed solution circulation are omitted from the present invention, the conditions for heterotrophic nitrifying and denitrifying bacteria to grow are not provided. In the mixed culture system, a mixed culture system mainly composed of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria is constructed, and nitrification and denitrification are performed by these bacteria. (2) However, as for the growth of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria, the pH of the mixed culture solution decreases along the flow direction of the biological reaction system, mainly due to the oxidation of ammonia of autotrophic nitrifying bacteria. Moreover, not only autotrophic nitrifying bacteria but also heterotrophic denitrifying bacteria are markedly inhibited in growth, resulting in incomplete nitrification and denitrification.

(3) As evidence that the autotrophic nitrifying bacteria have grown incompletely, the nitrification form in this system is obviously the nitrate form. Even if this system is established, heterotrophic denitrification is performed. It is extremely uneconomical because the bacterium requires a larger amount of hydrogen donor to reduce nitric oxide. (4) Hydrogen reduction in the final step by this method was not substantially performed, and although not shown as data, the use of hydrogen in the hydrogen reduction step was negligible. This is evidence that incomplete but heterotrophic denitrifying bacteria are growing as denitrifying bacteria in this method. Therefore, this is an extremely incomplete treatment method for the process of the present invention, which has a function of recovering hydrogen by using human waste as a potential energy substance and capable of completely nitrifying and denitrifying simultaneously. (5) From the above experimental results, it was proved that the circulation of the mixed culture solution from the aerobic tank and the selective tank of the present invention is an essential condition for making the heterotrophic nitrifying and denitrifying bacteria dominant. Was done.

Comparative Example 1 Nitrification and Denitrification Experiment at Low Dissolved Oxygen Concentration In the process of the present invention shown in FIG. 1, the selective tank was converted into an aerobic tank, and the final selective tank was not subjected to hydrogen reduction. Slowly aerated and dissolved oxygen concentration is 1 mg / l
A nitrification and denitrification experiment was carried out as described below and by injecting reduced sulfur. Although the experimental results are not particularly described, the pH of the mixed culture solution is 4.8 to 5.3 at the end portion in the flow direction, the nitrification rate is only about 55 to 60%, and the denitrification rate is 20% or less. It was observed that both autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria suffered growth inhibition. Naturally, no significant growth of heterotrophic nitrifying and denitrifying bacteria was also observed.
It was speculated that it is essential to provide at least a direct reduction step of nitric oxide with hydrogen gas in order to grow heterotrophic nitrifying and denitrifying bacteria in such an environment.

Example 2 (a) Aerobic nitrification and denitrification experiment of human excreta by multistage aerobic tank / selection tank process by heterotrophic nitrifying and denitrifying bacterium Thiosphaera pantotropha We selected a treatment plant that can obtain a relatively thick undiluted urine similar to the structure guideline, and conducted an aerobic nitrification and denitrification experiment of the human urine as a donor sample. Table 5 shows the physicochemical properties of the test urine. In addition, this sample was stored in a refrigerator at 5 ° C. or lower during the experimental period in order to prevent deterioration.

[0059]

[Table 5] (Note) * All units are shown in mg / l except pH. * Test urine is a sample filtered through a 1 mm open screen.

In the present embodiment, 5 tanks (2 steps x aerobic tank / selection tank + which are connected to a continuous aerobic nitrification denitrification tank and a final aerobic tank 5'shown in FIG. 3 are connected. An aerobic tank was constructed, and the final aerobic tank was used as a finishing tank in a broad sense. A gravity type sedimentation tank (solid-liquid separation tank) for the purpose of concentrating / separating bacterial cells, and a concentrated bacterial cell return route are provided.
An aerobic nitrification and denitrification experiment was conducted by continuous treatment. Further, in order to circulate and return the mixed culture solution in the aerobic tank, the selective tank, and the final aerobic tank, a pipe made of vinyl chloride was attached to each. The selection tank was provided with a stirrer for performing slow stirring, and was further provided with a cover to prevent the mixed culture solution from directly contacting the atmosphere. The flow sheet of the experiment is as shown in Fig. 3, but the following experimental equipment corresponding to this treatment process was assembled, undiluted urine was injected into the first-stage aerobic tank, and concentrated bacterial cells from the solid-liquid separation tank were assembled. Regarding the return of the above, an intermittent injection method was used, and all other liquids and gases were continuously injected and an air supply method (stirring in the selective tank was a continuous method). Air was continuously blown into each aerobic tank as described above. However, when undiluted and urine infusion was interrupted, the air blowing rate was extremely narrowed and the dissolved oxygen concentration in the tank liquid was 1 mg. Care was taken not to exceed 1 / l.

Experimental apparatus and experimental conditions * Conditions common to all treatment steps: Treated water temperature: 30 ± 1 ° C. All experimental apparatuses were installed in a large-sized constant temperature water tank and operated at the above temperature.・ Undiluted urine injection volume (processing volume): Q = 1 liter /
Day, * Individual experimental equipment and experimental conditions * Square aerobic nitrification and denitrification process: (aerobic tank 2 liters / selective tank 1 liter) x 2 stages) + final aerobic tank 2 liters ・ Total volume: 7.5Q = 7.5 liters, -BOD load for the total volume: about 1.3 kg / m ³ · day, -BOD sludge load for all tank sludge: about 0.1 kg / kg-day, NH ₄ -N for all tank sludge Sludge load: Approximately 0.038 kg / kg-day, but sludge concentration in the tank: 13,000 mg / l,

* Circulation sludge amount-Circulation amount to the rear aerobic tank / pre-stage aerobic tank: 15Q = 15 liters / day-Circulation amount to the final aerobic tank / pre-stage aerobic tank: 5Q = 5 liters / day , ・ Circulation amount to the latter-stage selection tank / the first-stage selection tank: 15Q = 15 liters / day, ★ Dwell time in each tank (retention time in each aerobic tank, one tank in the selected tank ・ ・ Calculated value) ・Retention time of undiluted urine in aerobic nitrification and denitrification step: 7.5 days, Retention time in aerobic tank 3: 2.28 hours, Retention time in aerobic tank 5: 2.28 hours, -Retention time in the final aerobic tank 5: 1.85 hours-Retention time in each selection tank: 1.5 hours However, the amount of returned sludge was ignored.

★ Aeration in aerobic tank ・ Aeration and stirring type aeration with a small blower ・ Dissolved oxygen concentration is automatically controlled to 1 mg / l or less by operating with dissolved oxygen concentration meter ★ Solid-liquid separation tank ・ Gravity type circular Settling tank ・ Volume: 2 liters ・ Concentrated sludge concentration: 15,000 to 18,000 mg / l The above relationship is simply illustrated in Fig. 4. In FIG. 4, the residence time in each tank is an apparent residence time with respect to the circulation amount of each mixed culture solution. The results of the verification experiment of aerobic nitrification and denitrification of undiluted urine obtained by the above experimental apparatus and experimental conditions are shown in Table 6 (average value for one month after the operation reached a steady state).

[0064]

[Table 6] (Note) *: All units other than pH are shown in mg / l. *: All analytical samples are the separation liquid of the centrifuge (1,500 G, 10 minutes). *; Presence of NO ₃ -N, the concentration negligible in all samples.

The results of the aerobic nitrification and denitrification verification experiment using undiluted urine heterotrophic nitrification and denitrification bacteria are summarized as follows. (1) By a process in which a two-stage aerobic tank / selection tank and a final aerobic tank are added, each mixed culture solution is returned to the preceding aerobic tank / selection tank, and nitrification and denitrification are performed according to the experimental conditions of (a). As a result of conducting a nitrogen treatment verification experiment, initially, incomplete nitrification and denitrification due to autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria progressed, but at the time when more than one month had passed since the start of operation. The autotrophic nitrifying bacterium and the heterotrophic denitrifying bacterium in the mixed culture solution are gradually culled by the process of the present invention, and instead, the heterotrophic nitrifying and denitrifying bacterium Tsa is gradually grown in the mixed culture system, Eventually, the number of bacteria increased and Tsa bacteria became a complete dominant species, and good aerobic nitrification and denitrification as shown in Table 6 were performed.

(2) This heterotrophic nitrifying and denitrifying bacterium was presumed to be Thiosphaera pantotropha based on its biological properties. This type of bacterium has the final form of ammonia oxidation as nitrite, which is advantageous from the viewpoint of supplying a hydrogen donor. Further, the present invention, in contrast to the conventional nitrifying and denitrifying method by the synergistic action of nitrifying bacteria and denitrifying bacteria, heterotrophic nitrifying and aerobic denitrifying by a group of bacteria called heterotrophic nitrifying and denitrifying bacteria. This is a biological nitrification denitrification method that is a process that is completed and is extremely excellent in terms of simplification of the treatment process, ease of operation management, and economic effects. (3) With the addition of the final oxidization tank, the heterotrophic nitrifying and denitrifying bacteria are more surely the dominant species, the nitrifying and denitrifying functions are almost perfect, and the final discharged water has an average value of only 3 mg / Only about 1 NH ₄ -N was detected, and NO _x -N was at a similar concentration.

(4) As shown in Table 6, PO ₄ -P was removed more than expected in the process of the present invention. Although the reason for this has not been elucidated, whether the environment change due to the combination of the aerobic tank / selective tank (anaerobic tank) induced the growth of the dephosphorization bacteria, or the heterotrophic nitrifying and denitrifying bacteria acquired the dephosphorization function. It is thought that either of them did. This is an important future research topic. (5) As described above, even in the nitrifying and denitrifying treatment of a rich organic wastewater such as human waste, by providing the final aerobic tank in the aerobic nitrifying and denitrifying step, not only the nitrifying and denitrifying function,
By installing this tank and circulating / returning the aerobic culture solution, the competitive relationship with other bacteria in the mixed culture system of heterotrophic nitrifying and denitrifying bacteria becomes more advantageous, and the bacteria will surely become the dominant species. Was confirmed.

(B) Experiment for confirming the effect of circulating and returning the mixed culture solution from the latter-stage selection tank to the former-stage selection tank. In the aerobic nitrification and denitrification process of the present invention shown in FIG. 3, the circulation of the mixed culture solution in the selection tank to the pre-selection tank is used to produce heterotrophic nitrifying and denitrifying bacteria which play the main role of the present invention. An experiment was conducted to confirm whether or not it is an essential condition for overcoming a competitive relationship and becoming a dominant species in a mixed culture system in which eutrophic nitrifying bacteria and heterotrophic denitrifying bacteria coexist. Regarding the experimental apparatus and the experimental conditions, in order to make the comparison with the experiment of (a) of Example 2 strict and to have objectivity, the circulation of the selective tank culture mixed solution was omitted, and ). Table 7 shows a comparison between the results of this experiment and the results of Example 2 (a).

[0069]

[Table 7] (Note) Notes are the same as in Table 6.

The experimental results for confirming the effect of the circulation of the mixed culture solution in the selective tank of Example 2 (b) are summarized as follows. (1) As can be easily understood from the experimental results of Table 7, from the operation of the process of the present invention, the circulation of the aerobic tank mixed culture solution is the same as the conventional one, and even if the circulation and return of the selective tank mixed culture solution is omitted,
Although the nitrifying and denitrifying function is slightly lower than that in (a) of Example 2, it is practically negligible, and the nitrifying and denitrifying bacterium by the non-diluted urine heterotrophic nitrifying and denitrifying bacterium used in this experiment is Almost completely achieved. (2) This means that even if the process of (b) of Example 2 is applied, heterotrophic nitrifying and denitrifying bacteria in a mixed culture system,
In the competitive relationship between autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria, even if the circulation of the selective tank mixed culture solution to the previous stage is omitted, there is still an environment where heterotrophic nitrifying and denitrifying bacteria dominate. It indicates that the residue is retained.

Although the reason for this has not been clarified, the autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria still remaining in the aerobic tank and the selective tank in the latter stage are transferred from the latter aerobic tank to the former aerobic tank. It is transferred to the aerobic tank at the forefront by the mixed culture circulated, and is repeatedly fed to the aerobic tank / selective tank in the process of flowing down the aerobic nitrification and denitrification process composed of a multi-stage aerobic tank / selective tank. It is considered that this is because it is exposed to the circulation and hinders smooth growth. From the results of this experiment, depending on the type of organic wastewater (concentration of BOD, NH ₄ —N, sulfide, lower fatty acid, etc.), circulation of the mixed culture solution from the aerobic tank is an effect of the mixed culture solution from the selection tank. It is judged that it possesses to some extent. However, the circulation and return of the mixed culture solution from the aerobic tank to the previous stage is called the selection of bacteria due to the dilution of the concentration of influent water into the aerobic nitrification and denitrification process and the repeated environmental conditions of the aerobic tank / selective tank. It is an essential condition from the viewpoint and cannot be omitted.

(C) Confirmation of necessity of circulation of aerobic tank mixed liquid and selection tank mixed liquid. In the aerobic nitrifying and denitrifying step of the present invention shown in FIG. 3, the circulation of each mixed culture solution causes the heterotrophic nitrifying and denitrifying bacteria that play the main role of the present invention to coexist with many other bacteria. Experiments were carried out to confirm whether it is an essential condition for making the dominant species in the mixed culture solution. Regarding the experimental apparatus and experimental conditions, the comparison between (a) of Example 2 and this experiment was carried out strictly,
In order to make the experimental results objective, the procedure was the same as in Example 2 (a) except that the circulation of the mixed culture solution was omitted.
The results of this experiment are summarized in Table 8.

[0073]

[Table 8] (Note) Notes are the same as in Table 6.

The experimental results for confirming the effect of the mixed culture solution circulation of (c) of Example 2 are summarized as follows. (1) As can be easily understood from the experimental results in Table 8, if the mixing tank mixed solution circulation operation and the selective tank mixed solution circulation operation are omitted from the present invention, heterotrophic nitrifying denitrifying bacteria proliferate predominantly. The conditions disappeared, and a mixed culture system composed mainly of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria was constructed.
Nitrification and denitrification are performed by these bacteria. (2) However, in the growth of autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria, the pH of the mixed culture solution decreases mainly in accordance with the ammonia oxidation of the autotrophic nitrifying bacteria, and Since the dissolved oxygen concentration of the mixed culture is controlled to be extremely low, the growth of not only autotrophic nitrifying bacteria but also heterotrophic denitrifying bacteria is simultaneously inhibited, resulting in incomplete nitrification and denitrification. (3) As evidence that incomplete but autotrophic nitrifying bacteria proliferated, the nitrification form in the system omitting the mixed culture circulation was nitric acid type, and even if this system was established, heterotrophic It is extremely uneconomical because a larger amount of hydrogen donor is required for the denitrifying bacteria to reduce nitrate. (4) From the above experimental results, it was proved that the circulation of the mixed culture solution from the aerobic tank and the selective tank of the present invention is an essential condition for making heterotrophic nitrifying and denitrifying bacteria the dominant species. It was

[0075]

As described in detail above, the present invention is an innovative technology based on an idea from a viewpoint and an idea which are completely different from those of the prior art, and has the following operational effects. (1) Focusing on the fact that sewage and sludge such as human waste contain not only nitrogen and phosphorus that are eutrophication-causing substances, but also usually sulfates or reduced sulfur. An extremely excellent treatment that not only produces hydrogen, which is clean energy, but also removes nitrogen by using reduced sulfur and hydrogen gas itself as hydrogen donors at the same time by the synergistic action of nutritional aerobic nitrifying and denitrifying bacteria. It is a technology and can contribute to the prevention of eutrophication in closed water areas or stagnant water areas. (2) A high-concentration pollution source, such as human waste itself, is not evaluated only as a pollutant, but is evaluated as a resource with a high potential potential, and human waste is used as a substrate to biologically produce hydrogen and also nitrogen. It is an innovative microbial utilization technology that has both production and decomposition functions that can be removed.

(3) In contrast to the conventional biological nitrification / denitrification method, which has a complicated treatment step because it is necessary to grow nitrifying and denitrifying bacteria which are functionally completely different in the process.
The technique of the present invention is a heterotrophic nitrifying and denitrifying bacterium having both functions in the aerobic nitrifying and denitrifying step, which is proliferated as a dominant species in a mixed culture system, and nitrifying and denitrifying is performed only by a genus of bacteria. The configuration is extremely simple and does not require high driving skill. (4) In the present invention, in order to supplement the hydrogen donor for denitrification, a part of the hydrogen produced in the hydrogen fermentation tank is branched and used, but the required amount is only 1/10 of the hydrogen production amount. Before and after, it has enough hydrogen production capacity to be used as an energy source. (5) With regard to pollutants other than phosphorus, the final treated water according to the technique of the present invention does not damage public water bodies and water systems even if it is directly discharged to the outside of the system. Usually, in the human waste treatment, phosphorus and chromaticity components are removed by physicochemical means / method, so that the treated water of the present invention may also be removed in accordance with a conventional method.

[Brief description of drawings]

FIG. 1 is a processing system diagram showing an example of an aerobic nitrification denitrification method of the present invention.

FIG. 2 is an explanatory diagram showing operating conditions of the first embodiment.

FIG. 3 is a processing system diagram showing another example of the aerobic nitrification denitrification method of the present invention.

FIG. 4 is an explanatory diagram showing operating conditions of the second embodiment.

[Explanation of symbols]

1: Sulfur-containing / ammonia-containing wastewater, 2: Hydrogen fermentation tank, 3,
5, 5 ': Aerobic tank, 4, 6: Selection tank, 7: Solid-liquid separation,
8: Treated water, 9: Generated gas, 10: Washing desulfurizer, 11:
Hydrogen sulfide water, 12: H ₂ + CO ₂ , 13: gas supply pipe,
14, 18: Blower, 15: Excess hydrogen, 16: Aerobic mixture circulation, 17: Selective mixture circulation, 19: Return sludge, 2
0: excess sludge,

Claims (8)

[Claims] 1. A method for biologically aerobic nitrifying and denitrifying organic sewage or sludge containing reduced sulfur, wherein an aerobic process and an anaerobic process are alternately arranged in multiple stages, and heterotrophic nitrification belonging to a sulfur-oxidizing bacterium is carried out. In each of the above steps under the control of denitrifying bacteria,
An aerobic nitrification and denitrification method characterized by performing nitrification and denitrification through organic sewage or sludge sequentially. 2. In each of the processes arranged in multiple stages, the aerobic process arranged in the latter stage to the aerobic process arranged in the former stage and / or the anaerobic process arranged in the latter stage is arranged in the former stage. The aerobic nitrification denitrification method according to claim 1, wherein the liquid in each process is circulated back to the anaerobic process. 3. The aerobic process is arranged at the final stage in each of the multi-stage processes, and the effluent water from the process is circulated back to all the aerobic processes at the preceding stage. 2. The aerobic nitrification denitrification method described in 2. 4. A method for biologically aerobic nitrifying and denitrifying organic sewage or sludge, which comprises performing the following steps (a) and (b). (A) A hydrogen fermentation step of contacting hydrogen-producing bacteria and sulfate-reducing bacteria with organic wastewater or sludge. (B) The reduced sulfur of step (a) is sequentially added to the aerobic / anaerobic step in which heterotrophic nitrifying and denitrifying bacteria belonging to a sulfur-oxidizing bacterium are arranged in multiple stages by alternately arranging aerobic and anaerobic steps. Nitrification and denitrification step of performing nitrification and denitrification through the effluent containing 5. The aerobic nitrification and denitrification method according to claim 4, wherein the following step (c) is performed after the nitrification and denitrification step (b). A hydrogen reduction step of supplying a hydrogen-containing gas to at least the nitrification-processed treatment liquid in steps (c) and (b) to completely denitrify the nitrogen oxides remaining in the treatment liquid. 6. The hydrogen fermentation step (a) is characterized in that the gas generated from the step is washed with water, and this washing effluent containing reduced sulfur is introduced into the nitrification denitrification step (b). Item 4. The aerobic nitrification denitrification method according to Item 4 or 5. 7. In the nitrification and denitrification step (b), an aerobic step arranged in a subsequent stage is changed to an aerobic step arranged in a preceding stage and / or an anaerobic step arranged in a succeeding stage is arranged earlier. The aerobic nitrification denitrification method according to claim 4, 5 or 6, wherein the liquid in each step is circulated and returned to the anaerobic step performed. 8. The aerobic nitrification denitrification according to claim 4, wherein solid-liquid separation is performed between the hydrogen fermentation step (a) and the nitrification denitrification step (b). Nitrogen method.