JPS5929092A - Treatment of sewage containing nitrogen component - Google Patents

Abstract

PURPOSE:To perform effectively a denitrification treatment while treating anaerobically sewage, by using the hydrogen sulfide generated in an anaerobic treatment stage in subjecting the sewage to denitrification reaction by autotrophic bacteria. CONSTITUTION:The sewage contg. nitrogen components such as crude night soil or the like is charged into an acid forming tank where the sewage is subjected to acid forming reaction. The sewage is then conducted together with the return liquid mixture and return sludge from a nitrification tank to a denitrification tank where these are anaerobically mixed and agitated and are thus subjected to a denitrification treatment. The hydrogen sulfide generated from the acid forming tank is added as sulfur at about 1 mol ratio based on 1 mol nitrate nitrogen. The liquid mixture from the denitrification tank is aerobically treated in the next nitrification tank and part of the nitrified liquid is returned to the denitrification tank. The remaining liquid is discharged as treated water through settling tank.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides waste water containing nitrogen components, such as human waste, sewage,
Other industrial wastewater, sludge generated from human waste treatment plants, and other organic waste 1''('''Tj;hl;'
! i: JIK IM*J 8'p) k%.

This invention relates to a method for physically denitrifying treatment.

In recent years, as wastewater treatment standards have become more sophisticated, denitrification treatment has become required. For example, in human waste treatment, a method is also adopted in which low-diluted or undiluted wastewater is biologically treated by nitrification and denitrification.

In the conventional biological denitrification method, wastewater is sequentially passed through an anaerobic denitrification tank and an aerobic nitrification tank, and a considerable amount of the nitrified liquid from the nitrification tank is circulated back to the denitrification tank. A method of removing BOD and denitrification by using organic matter in wastewater as a hydrogen donor, or oxidizing ammonia nitrogen from wastewater in a nitrification tank, and then denitrifying it without adding organic matter such as methanol. Methods such as reduction in a nitrogen tank are adopted.

On the other hand, due to the recent energy situation, attention has been paid to an anaerobic treatment method, which is a low-cost treatment method, instead of an aerobic treatment method for wastewater. This anaerobic treatment has the advantage of generating less sludge and recovering energy as methane gas.

Furthermore, in this anaerobic treatment, the organic matter in the sewage is first converted into extruded organic acids such as acetic acid, phlopionic acid, and butyric acid through the action of anaerobic tL liquefaction blue IU'fl putrefaction. A two-phase anaerobic treatment method has been proposed in which the gas formation reaction (methane production reaction), which converts the produced turrets (acid acid or methane) into methane, into two phases. ing.

This two-phase anaerobic treatment method uses conventional anaerobic (digestion) in one tank.
In comparison to the one-light induction digestion method, which requires multiple processing steps, further research into the treatment and the methane production reaction involved in combing it revealed that by using sulfate-reducing bacteria, the treatment efficiency could be further promoted, and the anaerobic treatment process could be improved. An effective treatment for wastewater that enables denitrification (elementary) treatment while treating wastewater anaerobically by performing a denitrification reaction through autotrophic microsealization using monosaturated hydrogen generated by We have proposed a method.

The above-mentioned anaerobic treatment method includes an acid production reaction and a methane production reaction. Among these, acids other than acetic acid produced in the acid production reaction, such as fropionic acid, are converted to methane by methanogens at a slow rate, which is the so-called rate-limiting reaction.

Therefore, decomposing propionic acid and the like into acetic acid at the stage of the acid production reaction increases the efficiency of anaerobic treatment.

In order to decompose glopyrenic acid, butyric acid, lactic acid, etc. to acetic acid, desulfovibrio (1) es Lll f
o-vibrio) or tesulfomacrum (Des
Sulfate-reducing bacteria such as ulfo-maculum) are effective, and the sulfur compounds used by these bacteria can be obtained by total oxidation of hydrogen sulfide obtained from an anaerobic treatment process, and SO ni+52o2+-
It is also possible to use other sulfur oxides such as.

The above-mentioned reduction reaction of flopionic acid by sulfate-reducing bacteria will be shown in the next step.

-C)(,C112CO(J-1-112(J+-71
12CO, ISO 3.3 4 - 11 5
3+Cl3COO-1-Co,,l
ll2S-)-H20+7HCO,,-1F0H-3
32 As is clear from the above formula, fropionic acid is decomposed with 1 mole of acetic acid, and at this time, 1 mole of sulfate ion is required per 1 mole of fluopionic acid.

When carrying out semi-total anaerobic injection treatment, the addition of sulfate ions is equivalent to the amount of organic carbon ((χ・J, 0) in the waste liquid.
: By having 3 to 3 times (molar ratio) or more of the acid present, various organic acids can be effectively decomposed into acetic acid.

Such a sulfuric acid reduction reaction can be carried out as an anaerobic treatment step 1. In other words, sulfur compounds such as sulfur ions are added in the above-mentioned amount to an acid-producing reaction tank, and mixed anaerobically in the same manner as in conventional acid-producing reactions. By stirring, organic matter can be decomposed into acetic acid form. This reaction operation may be the same as the conventional acid production reaction, and the subsequent methane production reaction may also be the same as the conventional one.

Therefore, in the methane production tank, methane gas can be effectively obtained by mainly converting acetic acid into methane.As a result, the reaction can be sped up by 20 to 30% compared to conventional methods. The capacity of 6J can be achieved by reducing the capacity of the processing reaction tank.

Now, autotrophic bacteria, such as Th1obacil'lus denitrif
Denitrifying bacteria such as 1cans) produce hydrogen sulfide (H2S).
, sulfide, sulfur (SO), or an oxidizable sulfur compound such as SOMI, 520H- is used as a hydrogen donor, and nitrate nitrogen is reduced to nitrogen gas by 1. Perform denitrification. This reaction can be expressed as follows.

0.42 zH2S-1-(1,422H8-+N01
-+〇, 347 Co2-t-o, o s 6 sNH
,++o,56sHco;-+0.8443o2-+0
．． 5N2+0.865C, H7Co240.4 PI
9) ("As is clear from this formula, 844 moles of sulfate ion (807 months) are required for every mol of nitric acid (NO;).

As this sulfate ion, hydrogen sulfide generated in the above-described anaerobic treatment process of wastewater can be used. In some cases, hydrogen sulfide may be added in the form of a desensitized soda by passing it through an all-alkaline solution.

Of course, it is necessary to add other sulfur or sulfur compounds to the -1 irregularity and to arrange the denitrification reaction in a circular manner.

Effective sewage treatment can be achieved by consecutively performing the former anaerobic treatment step using sulfate-reducing bacteria and the latter denitrification step using sulfur removal (vacuum).

That is, the present invention provides a method for treating wastewater containing nitrogen components in an anaerobic treatment system, and then in a nitrification-denitrification process. It is characterized by supplying hydrogen sulfide generated in the anaerobic treatment process to the denitrification reaction tank of the nitrification and denitrification process.

A process flora suitable for carrying out the invention is shown in FIGS. 1 and 2.

In the treatment flow shown in Figure 1, wastewater is first received in an acid generation tank, and organic matter in the wastewater is anaerobically crystallized in the presence of sulfate-reducing bacteria in addition to organic acid-producing bacteria. The mixture is then mixed and stirred while maintaining a predetermined pH, and is effectively decomposed into acetic acid form 1. The fAM ions added here are used by oxidizing hydrogen sulfide generated from this acid generation tank. Of course, you can use other sulfur compounds to make up for the shortage.

In the methane production tank, the acid production #, which has been decomposed mainly to acetic acid, is sent to the methane production tank, where it is heated at a predetermined temperature and y.
The mixture is mixed and stirred anaerobically while maintaining the pH at JZ to generate methane gas. This methane gas is recovered and effectively used as energy.

Next, the effluent from the methane generation tank is led to the denitrification tank together with the mixed liquid returned from the nitrification tank and the sludge returned from the settling tank, which will be described later. denitrification treatment. The addition of rice here is possible by bubbling hydrogen sulfide generated from the acid generation step in the anaerobic treatment tank 1'11 mentioned above. (In this case, this Akatsuki 1 arsenic is converted into an alkali m
, 'lV, and add it in the form of sulfuric acid.
Alternatively, if it is insufficient, other sulfur or sulfur compounds may be added.

The mixture from the denitrification tank is led to the nitrification tank, where it is aerobically nitrified, and the ammonia-11 nitrogen is nitrified to nitrate nitrogen. Most of the nitrified mixture is A portion of the sludge is returned to the denitrification tank, and a portion is separated in the sedimentation tank, and the supernatant liquid is discharged as treated water, while most of the solid content is sent as return sludge to the denitrification tank.

The process flow in Figure 2 is similar to the process flow in Figure 1 to generate methane! i! ! ! The process flow is completely omitted 2) o
Denitrification is also performed using eutrophic denitrifying bacteria such as Bacterium. Therefore, the explanation of this processing flow will be the same as the processing flow of FIG. 1 except for the function of the methane generation tank, so the description will be omitted to avoid duplication. However, the reason why this processing flow is eleven-fold is as follows.

In other words, the biological denitrification reaction that has been carried out since 11th century uses heterotrophic denitrifying bacteria, and at this time, organic matter (BOL) in wastewater and additive IJII are used as hydrogen donors.
All of the methanol is used. In this case, when the wastewater is sewage, only 60 to 70% of the nitrogen content can be denitrified by the BOD content. On the other hand, in the process flow shown in Figure 2, the organic acid generated in the acid generation tank can be used as a hydrogen donor, and hydrogen sulfide generated from the acid generation tank can also be denitrified by leading it to the denitrification tank. Can promote nitrogen reaction. There is also the advantage that less hydrogen sulfide is added in this case.

As described above, according to the present invention, by anaerobically treating wastewater, not only the amount of sludge generated is small, but also energy can be recovered as methane gas, and hydrogen sulfide generated from anaerobic treatment is effectively removed. It can be said that this is a useful invention that enables the denitrification reaction to be performed.

As the example wastewater, cow human waste (BOD 1+, o o omqB
, ammonia nitrogen 3.50 omq/, e) k,
It was processed using the processing flow shown in Figure 2.

Pour into the acid generation tank (effective volume 201) and set the temperature to 20 C.
()' The acid production reaction was carried out under the conditions of residence time of 10 days while adjusting the H6.5 to 7.5.

Next, the acid production liquid 1 was introduced into the denitrification tank together with iJ L, 4 times the amount of the returned mixed liquid from the nitrification tank, and 10 times the amount of the returned sludge, and mixed and stirred anaerobically, and the residence time () 5 Denitrification treatment was carried out under the conditions of 1 day. Here, hydrogen sulfide generated from the acid generation tank was added at a ratio of 7.1 mol to 1 mol of nitrate nitrogen.

The mixed liquid from the denitrification tank is aerobically treated in the next nitrification tank to achieve a nitrification rate of 98%, and as mentioned above, part of the nitrification liquid goes to the denitrification tank and the rest goes through the settling tank. Discharged as treated water.

Processing at this time 7. K Water quality is B OD 30t++
! //-Q.

It was T-N8m9/13.

Note that when hydrogen sulfide from the acid generation tank was not added to the denitrification tank, 801) in the treated water did not change, but T
-Ns4. It showed a high value of amri/-e.

As described above, according to the present invention, ammonia nitrogen can be effectively removed from wastewater.

[Brief explanation of drawings]

Figures 1 and 2 (show a processing flow 1 suitable for carrying out the present invention).

Claims (1)

[Claims] l Consisting of a process in which wastewater containing nitrogen components is treated in an anaerobic treatment process and then in a nitrification-denitrification process, and the hydrogen sulfide generated in the anaerobic treatment process is converted into an autotrophic nutrient during the nitrification-denitrification process. A method for treating wastewater containing nitrogen components, characterized by supplying wastewater to a denitrification tank that denitrifies using bacteria. 2. The method for treating wastewater containing nitrogen components according to claim 1, wherein the anaerobic treatment step is a two-phase anaerobic treatment of an acid production reaction and a methane production reaction. 3 The anaerobic treatment step is an acid production reaction treatment, i/
[A method for treating IPJ water containing a nitrogen component as set forth in claim 1.