JP2001170685A - Treating device for nitrogen-containing waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating device for nitrogen-containing waste water which is capable of stably obtaining treated water of consistent water quality even if the oxidative nitrogen concentration of the treated water fluctuates largely. SOLUTION: This device has an inflow oxidative nitrogen measuring means 15 which measures the oxidative nitrogen concentration in the water to be treated to flow into a denitrification tank 10, an organic matter injecting means 13 for organic matter into the denitrification tank and an organic matter injection rate control means 14 for controlling the organic matter injection rate from the organic matter injecting means 13. The organic matter injection rate control means 14 has an arithmetic section which computes the required amount of the organic matter in accordance with the inflow nitrogen concentration measured by the inflow oxidative nitrogen measuring means 15 and a control section which controls the organic matter injection rate from the organic matter injecting means 13 in accordance with the result computed by the arithmetic section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating nitrogen-containing wastewater, and more particularly, to an apparatus for treating nitrogen-containing wastewater that includes a step of biologically removing nitrogen contained in the wastewater by microorganisms. .

[0002]

2. Description of the Related Art As a wastewater treatment apparatus for removing nitrogen from wastewater, a conventional anaerobic and aerobic activated sludge method (circulating nitrification denitrification method) combining an anaerobic (anoxic) tank and an aerobic tank has been used. )
Is widely practiced. This anaerobic and aerobic activated sludge method is to allow the water to be treated, such as inflow sewage, to flow into the anoxic tank, and to circulate the nitrifying liquid from the aerobic tank and the return sludge from the final sedimentation tank to the anoxic tank. In the aerobic tank, in the aerobic tank, the ammonia nitrogen flowing through the anoxic tank is oxidized to nitrite or nitrate nitrogen, and these are circulated to the anoxic tank as a nitrifying solution, thereby Oxidized nitrogen is reduced to nitrogen gas by an oxidation reaction with organic matter in the influent water and removed from the water. In addition, although other types of denitrification methods are also used, basically, the reaction is a reaction in which ammoniacal nitrogen is oxidized to oxidized nitrogen, and oxidized nitrogen is reduced to nitrogen gas.

[0003] In performing the above-mentioned denitrification treatment, nitrogen removal by reduction of biological oxide nitrogen in an anoxic tank, that is, in the denitrification treatment, in the case of standard municipal sewage, the denitrification is carried out. It is not necessary to add an organic substance, but when the BOD in the water to be treated is low, it is necessary to add an organic substance such as methanol to the oxygen-free tank as a hydrogen donor.

As described above, when methanol or the like is added to an oxygen-free tank, for example, Japanese Patent No. 2,643,478 discloses that a mixed liquid or a processing liquid in a reaction tank is taken out and the concentration of oxidized nitrogen is measured. It is disclosed that a methanol injection amount or the like is controlled based on the result.

[0005]

However, as described above, in the case of taking out the mixed solution or the processing solution in the reaction tank and measuring the concentration of oxidized nitrogen, the nitrogen content in the influent water (the water to be treated) is not considered. Even if the value greatly changes, the nitrogen concentration in the reaction tank changes only little by little, so that it may be hidden in a normal fluctuation range, and appropriate control may not be performed. In addition, even if the injection amount of methanol is increased after the oxidized nitrogen concentration in the tank exceeds a predetermined value, it cannot follow the nitrogen concentration of the water to be treated, and as a result, it is impossible to guarantee a constant water quality. I will. Therefore, the method described in the above publication,
Although effective for batch type nitrogen removal, it is difficult to apply to other types.

Therefore, according to the present invention, even if the concentration of oxidized nitrogen in the water to be treated flowing into the denitrification tank (reaction tank, anoxic tank) fluctuates greatly, it is possible to stably obtain treated water having a constant water quality. It is an object of the present invention to provide an apparatus for treating nitrogen-containing wastewater.

[0007]

In order to achieve the above object, a nitrogen-containing wastewater treatment apparatus according to the present invention is a wastewater treatment apparatus having a denitrification tank for biologically converting oxidized nitrogen into nitrogen. Inflow oxidized nitrogen measurement means for measuring the concentration of oxidized nitrogen in the water to be treated flowing into the nitrification tank, organic substance injection means for injecting organic substances into the denitrification tank, and organic substance injection amount for controlling the amount of organic substances injected from the organic substance injection means Control means, wherein the organic substance injection amount control means calculates a required amount of organic substance based on the inflowing nitrogen concentration measured by the inflowing oxidized nitrogen measurement means, and a calculation section based on a calculation result in the calculation section. And a control unit for controlling the amount of organic substance injected from the organic substance injection means.

Further, the apparatus for treating nitrogen-containing wastewater of the present invention comprises a treated hydroxylated nitrogen measuring means for measuring an oxidized nitrogen concentration in treated water in the denitrification tank or treated water flowing out of the denitrification tank, The calculation unit of the organic substance injection amount control means,
The required amount of organic matter is calculated based on the inflow nitrogen concentration and the treated water nitrogen concentration measured by the treated hydroxylated nitrogen measurement means, and in particular, the organic matter injection amount control means comprises the inflow nitrogen concentration And storage means for storing the treated water nitrogen concentration and the organic substance injection amount with time, respectively.
A nitrogen removal amount calculation unit for obtaining the nitrogen removal amount in the denitrification tank from the inflow nitrogen concentration and the treated water nitrogen concentration, and a correlation between the nitrogen removal amount obtained by the nitrogen removal amount calculation unit and the organic substance injection amount is obtained. A correlation calculation unit, wherein the calculation unit calculates a required amount of organic matter based on the correlation obtained by the correlation calculation unit and the inflowing nitrogen concentration.

Further, the denitrification tank is provided with sludge concentration measuring means for measuring the activated sludge concentration in the tank, and the arithmetic unit of the organic substance injection amount control means calculates the activated sludge concentration measured by the sludge concentration measuring means. The organic matter injection amount control means stores the inflow nitrogen concentration, the treated water nitrogen concentration, the organic matter injection amount, and the activated sludge concentration with time, respectively. A storage unit, a nitrogen removal amount calculation unit for obtaining the nitrogen removal amount in the denitrification tank from the inflow nitrogen concentration and the treated water nitrogen concentration, and a nitrogen removal amount and the activated sludge concentration obtained by the nitrogen removal amount calculation unit. A nitrogen removal rate calculator for determining a nitrogen removal rate per unit sludge concentration, and a correlation for determining a correlation between the nitrogen removal rate determined by the nitrogen removal rate calculator and the organic substance injection amount. Includes a detection section, the arithmetic unit is characterized in that for calculating the required amount of organic matter on the basis of said inlet nitrogen concentration correlates obtained in the correlation calculating section.

Further, an inflow water amount measuring means for measuring a flow rate of the water to be treated flowing into the denitrification tank, and a treatment time in the denitrification tank are calculated based on the inflow water amount measured by the inflow water amount measurement means. Characterized in that it is provided with treated water amount control means for controlling the treated water amount in the denitrification tank based on the treatment time,
The denitrification tank thus formed is provided between an upstream nitrification tank and a downstream chemical oxidation treatment tank.

[0011]

FIG. 1 is a system diagram showing a first embodiment of a nitrogen-containing wastewater treatment apparatus according to the present invention. The nitrogen-containing wastewater treatment apparatus includes a denitrification tank 10 that performs a biological denitrification treatment, that is, a treatment that biologically converts oxidized nitrogen into nitrogen, and allows the water to be treated to flow into the denitrification tank 10. The treated water inflow path 11, the treated water outflow path 12 through which treated water treated in the denitrification tank 10 flows out, the organic substance injection means 13 for injecting an organic substance such as methanol into the denitrification tank 10, and the organic substance injection means 13 And an inflowing oxidized nitrogen measuring means 15 for measuring the concentration of oxidized nitrogen in the treated water flowing through the treated water inflow path 11.

In the wastewater treatment apparatus formed as described above, the amount of nitrogen removed in the denitrification tank 10 (the amount of nitrogen removal M) and the concentration of oxidized nitrogen in the water to be treated flowing from the inflow path 11 for treated water. M = F (Cin−) between the (inflow nitrogen concentration Cin), the oxidized nitrogen concentration in the treated water flowing out of the treated water outflow path 12 (treated water nitrogen concentration Cout), and the treated water amount (inflow water amount F). (Cout).

If the inflow water amount F and the treated water nitrogen concentration Cout are constant, the nitrogen removal amount M can be calculated by measuring the inflow nitrogen concentration Cin. Therefore, if the correlation between the nitrogen removal amount M and the organic substance injection amount is determined in advance, the correlation between the nitrogen removal amount M and the organic substance injection amount indicates that the organic substance injection means 13 has the function of the denitrification tank 1.
It is possible to calculate the amount of organic substances to be injected into zero.

That is, in the present embodiment, the organic substance injection amount control means 14 is provided with the inflowing oxidized nitrogen measurement means 15.
A calculation unit for calculating the required amount of organic matter based on the inflow nitrogen concentration Cin measured in step 1, and a control unit for controlling the amount of organic matter injected from the organic matter injection means 13 based on the calculation result of the calculation unit. The control unit controls the opening and closing of the flow control valve provided in the organic substance injection means 13 and adjusts the rotation speed of the pump in accordance with the organic substance injection amount calculated by the arithmetic unit, and adjusts the organic substance amount injected into the denitrification tank 10 by a predetermined amount. Adjust to

By this, an appropriate amount of organic matter corresponding to the concentration of oxidized nitrogen in the water to be treated flowing into the denitrification tank 10 can be injected into the denitrification tank 10, so that the concentration of oxidized nitrogen in the water to be treated is reduced. Even if it fluctuates greatly, the denitrification treatment can be performed reliably with a predetermined amount of organic matter, and the concentration of oxidized nitrogen in the treated water can be maintained at a certain concentration or less.

Incidentally, the measurement of the concentration of oxidized nitrogen was carried out at a wavelength of 2
Absorbance at 20 ± 14 nm, preferably 220 ± 5 nm, and 250 ± 14 nm, preferably 250 ± 10 n
It can be determined from the difference from the absorbance at m. For example, after extracting an appropriate amount of test water and filtering, the absorbance in both wavelength ranges is measured to determine the difference, and the absorbance difference can be subjected to a predetermined operation to determine the oxidized nitrogen concentration. .

FIG. 2 is a system diagram showing a second embodiment of the apparatus for treating nitrogen-containing waste water according to the present invention. In the following description, the same components as those of the first embodiment will be denoted by the same reference numerals, and detailed description will be omitted.

In this embodiment, in addition to the apparatus of the first embodiment, a treated hydroxylated nitrogen measuring means 16 for measuring the concentration of oxidized nitrogen in the treated water flowing out of the denitrification tank 10 is provided in the treated water outflow path 12. The calculation unit of the organic substance injection amount control means 14 calculates the required amount of organic substances including the concentration of treated water nitrogen measured by the treated hydroxylated nitrogen measuring means 16 in addition to the concentration of inflow nitrogen. Things. For example, for the organic substance injection amount calculated based on the inflowing nitrogen concentration,
When the concentration of nitrogen in the treated water increases or decreases, a correction for increasing or decreasing the amount of injected organic matter is performed. Thereby, even if the environment in the denitrification tank 10 fluctuates, the oxidized nitrogen concentration of the treated water can be maintained at a certain concentration or less.

Further, a storage means such as a memory or a disk device for storing the inflow nitrogen concentration Cin, the treated water nitrogen concentration Cout, and the organic matter injection amount Y over time into the organic substance injection amount control means 14; Treated water nitrogen concentration C
a nitrogen removal amount calculation unit for obtaining the nitrogen removal amount M in the denitrification tank 10 from the out, and a correlation calculation unit for obtaining a correlation between the nitrogen removal amount M obtained by the nitrogen removal amount calculation unit and the organic substance injection amount. Is provided by the calculation unit, and the correlation calculated by the correlation calculation unit and the inflowing nitrogen concentration Ci are calculated.
By calculating the required amount of organic matter based on n
Since an appropriate amount of organic substance can be injected in response to a change in the nitrogen concentration of the inflowing nitrogen and the nitrogen concentration of the treated water with time, for example, a change in the daytime or nighttime, more effective nitrogen removal can be performed.

Incidentally, instead of measuring the concentration of nitrogen oxides in the treated water flowing out of the denitrification tank 10, the concentration of nitrogen oxides in the denitrification tank 10 may be measured. It is possible to calculate the nitrogen removal amount.

FIG. 3 is a system diagram showing a third embodiment of the apparatus for treating nitrogen-containing waste water according to the present invention. In this embodiment, the second
In addition to the apparatus of the embodiment, a sludge concentration measuring means 17 for measuring the activated sludge concentration in the denitrification tank 10 was provided in the denitrification tank 10, and the sludge concentration measuring means 17 measured in addition to the inflow nitrogen concentration and the treated water nitrogen concentration. The required amount of organic matter including the activated sludge concentration is calculated. For example, correction is made to increase or decrease the amount of injected organic matter in accordance with the increase or decrease in the activated sludge concentration. When the treated water nitrogen concentration is fixed, the treated hydroxylated nitrogen measuring means 16 is not provided, and the inflowing nitrogen concentration measured by the inflowing oxidized nitrogen measuring means 15 and the activated sludge concentration measured by the sludge concentration measuring means 17 are not provided. Thus, the organic substance injection amount can be calculated.

The organic substance injection amount control means 14 includes:
Storage means for storing the inflow nitrogen concentration, the treated water nitrogen concentration, the organic matter injection amount, and the activated sludge concentration over time, respectively, and the nitrogen removal amount for obtaining the nitrogen removal amount in the denitrification tank 10 from the inflow nitrogen concentration and the treated water nitrogen concentration A calculation unit, a nitrogen removal rate calculation unit that calculates a nitrogen removal rate per unit sludge concentration from the nitrogen removal amount determined by the nitrogen removal amount calculation unit and the activated sludge concentration, and a nitrogen removal rate calculated by the nitrogen removal rate calculation unit. A correlation calculation unit for obtaining a correlation between the removal rate and the organic substance injection amount; and a calculation unit for calculating a required amount of the organic substance based on the correlation obtained by the correlation calculation unit and the inflowing nitrogen concentration. Thereby, the ability to remove nitrogen in the activated sludge can be effectively used in accordance with the temporal variation of the concentration of the inflowing nitrogen, and the nitrogen can be removed efficiently.

FIG. 4 is a system diagram showing a fourth embodiment of the apparatus for treating nitrogen-containing waste water according to the present invention. In this embodiment, the second
In addition to the apparatus of the embodiment, an inflow water tank 18 is provided upstream of the denitrification tank 10.
And an inflow water amount measuring means 19 for measuring the flow rate of the water to be treated flowing into the inflow water tank 18;
A treatment water amount control means 20 for controlling the flow rate of the water to be treated flowing from 8 into the denitrification tank 10 is provided, and the amount of inflow water is used as one of the control data.

Usually, in sewage treatment facilities, time zones, seasons,
The amount of inflow water fluctuates depending on the weather, and when the amount of inflow water fluctuates, the nitrogen concentration in the inflow water (water to be treated) often fluctuates. Generally, as the amount of water increases, the nitrogen concentration tends to decrease, and as the amount of water decreases, the nitrogen concentration tends to increase. That is, even if the water amount or the nitrogen concentration fluctuates, the fluctuation of the total nitrogen amount to be treated does not become so large.

Therefore, even when the residence time in the denitrification tank 10 is shortened when the amount of inflow water becomes large, a sufficient denitrification treatment can be performed. By controlling the amount of organic matter injected based on the measured inflow nitrogen concentration and the amount of inflow water, an optimal denitrification treatment according to the amount of inflow water can be performed. In addition,
The relationship between the inflow water amount and the treated water amount may be set in advance according to the treatment capacity of the denitrification tank 10 and the like.

That is, even when the amount of inflow water is large, since the nitrogen concentration is low, a sufficient denitrification treatment can be performed by shortening the residence time (treatment time) in the denitrification tank 10 and increasing the amount of treated water. It is possible to cope with an increase in the inflow amount with compact equipment without increasing the size of the nitrification tank 10.

FIG. 5 is a system diagram showing a fifth embodiment of the apparatus for treating nitrogen-containing waste water according to the present invention. In this embodiment, the denitrification tank 10 as described in each of the above embodiments is installed between a nitrification tank 21 for removing ammonia nitrogen in an aerobic atmosphere and a chemical oxidation treatment tank 22 for performing a chemical oxidation treatment. It was done. As the chemical oxidation treatment method, ozone, ultraviolet light, hydrogen peroxide, a combination of two or more of these, or a combination of one or more of these with a photocatalyst or an oxidation catalyst can be used. By performing this chemical oxidation treatment, in addition to sterilization, deodorization, and decolorization, it is possible to remove hardly decomposable organic substances.

In the nitrification tank 21, if nitrification failure occurs due to a sudden change in the amount of treated water or the amount of inflowing nitrogen, nitrite may be generated. This nitrous acid becomes a scavenger in the chemical oxidation treatment in the chemical oxidation treatment tank 22 and consumes an oxidizing agent such as ozone. Therefore, if nitrite is present in the denitrification treatment water flowing into the chemical oxidation treatment tank 22, The use efficiency of the oxidizing agent is greatly reduced.

Therefore, by installing the denitrification tank 10 provided with the organic substance injection amount control means 14 and the like between the nitrification tank 21 and the chemical oxidation treatment tank 22, nitrite in the nitrification treatment water from the nitrification tank 21 is provided. Even if the concentration suddenly increases, nitric acid is completely removed in the denitrification tank 10 by performing a denitrification treatment while injecting a necessary amount of organic matter based on the inflowing nitrogen concentration measured by the inflowing oxidized nitrogen measuring means 15 and the like. Therefore, nitrous acid does not flow into the chemical oxidation treatment tank 22, and the oxidizing agent in the chemical oxidation treatment tank 22 is effectively used, that is, the chemical oxidation treatment in the chemical oxidation treatment tank 22 is efficiently performed. Can be.

As shown in the fifth embodiment, the processing apparatus of the present invention can be combined with various types of processing. In addition to the above-mentioned circulating type nitrification and denitrification method, a two-stage circulating type It is also applicable to a denitrification method and the like.

[0031]

As described above, according to the apparatus for treating nitrogen-containing waste water of the present invention, the amount of organic matter injected is controlled in accordance with the concentration of oxidized nitrogen flowing into the denitrification tank, so that it flows into the denitrification tank. Even if the concentration of oxidized nitrogen in the water to be treated fluctuates greatly, treated water with a constant water quality can be stably obtained.
Furthermore, by controlling the organic matter injection amount by adding the oxidized nitrogen concentration in the discharged treated water and the time-varying factors,
The denitrification treatment can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of an apparatus for treating nitrogen-containing wastewater of the present invention.

FIG. 2 is a system diagram showing a second embodiment of the processing apparatus.

FIG. 3 is a system diagram showing a third embodiment of the processing apparatus.

FIG. 4 is a system diagram showing a fourth embodiment of the processing apparatus.

FIG. 5 is a system diagram showing a fifth embodiment of the processing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Denitrification tank, 11 ... Treatment water inflow path, 12 ... Treatment water outflow path, 13 ... Organic substance injection means, 14 ... Organic substance injection amount control means, 15 ... Inflow oxidized nitrogen measurement means, 16 ... Treatment hydroxylated nitrogen Measuring means, 17: Sludge concentration measuring means, 18
... inflow water tank, 19 ... inflow water amount measuring means, 20 ... treatment water amount control means, 21 ... nitrification tank, 22 ... chemical oxidation treatment tank

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tatsuhiko Suzuki 1-3-3 Kyobashi, Chuo-ku, Tokyo F-term (reference) 4D040 AA61 BB02 BB22 BB91 BB93

Claims (7)

[Claims] 1. A wastewater treatment apparatus having a denitrification tank for biologically converting oxidized nitrogen into nitrogen, wherein inflow oxidized nitrogen measuring means for measuring the concentration of oxidized nitrogen in the water to be treated flowing into the denitrification tank. An organic substance injection means for injecting an organic substance into the denitrification tank, and an organic substance injection quantity control means for controlling an organic substance injection quantity from the organic substance injection means, wherein the organic substance injection quantity control means is the inflowing oxidized nitrogen measuring means. An arithmetic unit for calculating the required amount of organic matter based on the measured inflowing nitrogen concentration, and a control unit for controlling the amount of organic matter injected from the organic matter injection means based on the calculation result in the arithmetic unit. Characteristic nitrogen wastewater treatment equipment. 2. A processing hydroxylated nitrogen measuring means for measuring a concentration of oxidized nitrogen in treated water in the denitrification tank or treated water flowing out of the denitrification tank, and an arithmetic unit of the organic substance injection amount control means includes: 2. The nitrogen-containing wastewater treatment apparatus according to claim 1, wherein a required amount of organic matter is calculated based on the inflow nitrogen concentration and the treated water nitrogen concentration measured by the treated hydroxylated nitrogen measuring means. 3. The organic matter injection amount control means includes a storage means for storing the inflow nitrogen concentration, the treated water nitrogen concentration, and the organic matter injection amount with time, respectively, and an inflow nitrogen concentration and a treated water nitrogen concentration. A nitrogen removal amount calculation unit for obtaining the nitrogen removal amount in the denitrification tank; and a correlation calculation unit for obtaining a correlation between the nitrogen removal amount obtained by the nitrogen removal amount calculation unit and the organic substance injection amount, wherein the calculation is performed. 3. The apparatus for treating nitrogen-containing wastewater according to claim 2, wherein the unit calculates a required amount of organic matter based on the correlation obtained by the correlation calculation unit and the inflowing nitrogen concentration. 4. The denitrification tank is provided with a sludge concentration measuring means for measuring the activated sludge concentration in the tank, and an arithmetic unit of the organic substance injection amount control means calculates the activated sludge concentration measured by the sludge concentration measuring means. 4. The apparatus for treating nitrogen-containing wastewater according to claim 1, wherein the required amount of organic matter is calculated. 5. The denitrification tank is provided with a sludge concentration measuring means for measuring the activated sludge concentration in the tank, and the organic substance injection amount control means comprises the inflow nitrogen concentration, the treated water nitrogen concentration, and the organic substance injection amount. And a storage means for storing the activated sludge concentration over time, a nitrogen removal amount calculation unit for determining the nitrogen removal amount in the denitrification tank from the inflow nitrogen concentration and the treated water nitrogen concentration, and the nitrogen removal amount calculation unit A nitrogen removal rate calculating unit for obtaining a nitrogen removal rate per unit sludge concentration from the nitrogen removal amount obtained in the above and the activated sludge concentration, and between the nitrogen removal rate obtained by the nitrogen removal rate calculation unit and the organic substance injection amount. A correlation calculation unit for determining the correlation of
3. The nitrogen-containing wastewater treatment device according to claim 2, wherein the calculation unit calculates a required amount of organic matter based on the correlation obtained by the correlation calculation unit and the inflowing nitrogen concentration. 4. 6. An inflow water amount measuring means for measuring a flow rate of the water to be treated flowing into the denitrification tank, and a processing time in the denitrification tank is calculated based on the inflow water amount measured by the inflow water amount measurement means. 6. The apparatus for treating nitrogen-containing wastewater according to claim 1, further comprising a treated water amount control means for controlling the treated water amount in the denitrification tank based on the treatment time. 7. The nitrogen-containing tank according to claim 1, wherein the denitrification tank is provided between an upstream nitrification tank and a downstream chemical oxidation treatment tank. Wastewater treatment equipment.