JPH0919698A - Advanced treatment of waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an advanced treatment method capable of simultaneously and efficiently removing organic matters and nitrogen from waste water without adding a hydrogen donor from the outside in a denitrifying process even though a denitrifying tank following a nitration tank is installed. SOLUTION: In a method for removing organic matters and nitrogen from the waste water containing organic matters and nitrogen with a nitration process and subsequently with a denitrifying process, the organic matters in the waste water is preliminarily adsorbed with activated carbon in a organic matter adsorbing tank 3 and the waste water is introduced into the nitration tank 4 and the activated carbon adsorbed the organic matters is introduced into the denitrifying tank 6, and the organic matters adsorbed on the activated carbon is utilized as the hydrogen donor required for the denitrification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an advanced treatment method for wastewater containing organic matter and nitrogen.

[0002]

2. Description of the Related Art As a method for treating organic matters and nitrogen in wastewater, a circulation type nitrification denitrification method which is a biological method is generally used. The reaction tank is composed of a denitrification tank and a nitrification tank, and wastewater containing organic matter and nitrogen flows into the denitrification tank. The denitrification tank outflow tank flows into the nitrification tank, and the ammonia nitrogen (NH ₄ —N) in the wastewater is converted into nitrate nitrogen (NO ₃ −) by nitrifying bacteria.
N) is converted (nitrification). The nitrified mixed liquid is circulated to a denitrification tank, where NO ₃ -N in the mixed liquid is converted into nitrogen gas by denitrifying bacteria using organic matter in the wastewater as a hydrogen donor, and nitrogen is removed from the wastewater. Further, the organic matter in the wastewater is used for denitrification in the denitrification tank, and is also oxidized and decomposed in the nitrification tank to be removed from the wastewater. However, in this method, since the nitrification tank is installed after the denitrification tank, N
O ₃ -N cannot be completely denitrified, and N 3
O ₃ -N remains.

The endogenous denitrification method, which is also a biological method, is
A denitrification tank is installed after the nitrification tank. In this method, the total nitrogen concentration in the treated water, that is, the sum of NH ₄ —N, NO ₃ —N and NO ₂ —N, can be made lower than in the circulating nitrification denitrification method, but the organic matter necessary for denitrification is However, there was a problem that the denitrification rate was reduced because the nitrification tank was oxidized. Therefore, methanol or the like may be added to increase the denitrification rate.

[0004]

DISCLOSURE OF THE INVENTION The present invention is also applicable to a wastewater treatment apparatus having a denitrification tank installed after a nitrification tank, in which organic substances and nitrogen are simultaneously discharged from the wastewater without adding a hydrogen donor from the outside in the denitrification process. It is an object to provide an advanced treatment method for wastewater that can be efficiently removed.

[0005]

According to the present invention, an organic substance is adsorbed by activated carbon before nitrification treatment of wastewater, the activated carbon adsorbing the organic substance is supplied to a denitrification treatment, and the hydrogen donor necessary for denitrification of the organic substance. The above problem is solved by using the above. That is, the advanced treatment method of wastewater according to the present invention is a method of removing organic matter and nitrogen from wastewater containing organic matter and nitrogen by a nitrification step, and then a denitrification step, by adsorbing organic matter in the wastewater to activated carbon in advance, Introduce the activated carbon that has absorbed the denitrification process,
It is characterized in that the organic matter adsorbed on the activated carbon is used as a hydrogen donor necessary for denitrification.

When carrying out the advanced treatment method of wastewater according to the present invention, a treatment apparatus in which an organic matter adsorption tank, a nitrification tank and a denitrification tank are installed in this order is used. Activated carbon is filled in the organic matter adsorption tank, and the wastewater in which the organic matter is adsorbed and removed by the activated carbon is introduced into the nitrification tank. In the nitrification tank, organic nitrogen and ammonia nitrogen are oxidized to nitric acid by nitrification. Next, the nitrification mixture is introduced into a denitrification tank, and nitrate nitrogen is changed to nitrogen gas by denitrifying bacteria to denitrify,
Denitrification requires the presence of organic matter as a hydrogen donor.
Therefore, in the present invention, activated carbon that has adsorbed the organic substance in the organic substance adsorption tank is put into the denitrification tank, and the organic substance adsorbed by the activated carbon is used as a hydrogen donor necessary for denitrification.

According to the present invention, since the denitrification tank is installed in the latter stage of the nitrification tank, theoretically, the nitrogen concentration of the treated water can be made zero. In addition, since the organic substances necessary for denitrification are adsorbed on the activated carbon in the front stage of the nitrification tank and put into the denitrification tank, the denitrification rate is higher than the denitrification rate of the endogenous denitrification method, Similar to speed. Moreover, denitrification can be efficiently advanced after nitrification, and at that time, it is not necessary to add an organic substance to the denitrification tank.

The activated carbon used in the denitrification tank can be returned to the organic matter adsorption tank for reuse. At this time, if it is considered that a large amount of organic matter still remains in the activated carbon to be returned, the activated carbon is not directly returned to the organic matter adsorption tank, but is once returned to the nitrification tank where the residual organic matter is oxidatively decomposed. It is preferable to return it to the organic substance adsorption tank. As a result, the adsorbing ability of the activated carbon is sufficiently recovered and then returned to the organic substance adsorption tank, so that the breakthrough of the activated carbon can be prevented.

Further, according to the advanced treatment method of the present invention, activated carbon is filled in both the organic matter adsorption tank and the denitrification tank, and the flowing direction of the wastewater can be switched to efficiently remove the organic matter and nitrogen. That is, the treatment tanks are arranged in the order of the first activated carbon tank, the nitrification tank, and the second activated carbon tank.
Organic matter is adsorbed in the activated carbon tank, nitrification is performed in the nitrification tank, and then denitrification is performed in the second activated carbon tank. After a predetermined time, raw water is introduced into the second activated carbon tank, where the organic matter is adsorbed by the activated carbon, Next, nitrification is performed, and denitrification is performed in the first activated carbon tank. In this way, by switching the flow direction of the wastewater every predetermined time, it is possible to efficiently remove the organic matter and nitrogen in the wastewater without moving the activated carbon.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on embodiments with reference to the drawings. FIG. 1 is a system diagram showing a first embodiment of the advanced wastewater treatment method of the present invention. In FIG.
The waste water is introduced into the organic matter adsorption tank 3 filled with the activated carbon 2 through the raw water introduction pipe 1. The wastewater from which the organic substances have been adsorbed and removed is then introduced into the nitrification tank 4, and the organic nitrogen and ammonia nitrogen in the wastewater are oxidized to nitrate nitrogen. The activated carbon 2 that has adsorbed the organic matter in the wastewater in the organic matter adsorption tank 3 is transferred by the activated carbon transfer pipe 5 to the denitrification tank 6 provided at the subsequent stage of the nitrification tank 4. In the denitrification tank 6, the denitrification bacteria denitrify the nitrate nitrogen flowing from the nitrification tank 4 by using the organic matter adsorbed on the activated carbon 2. The denitrified waste water is discharged from the drain pipe 7 as treated water. On the other hand, the activated carbon 2 used for denitrifying the organic matter is returned to the organic matter adsorption tank 3 through the activated carbon return pipe 8. According to this example, denitrification can be efficiently performed at a high denitrification rate without adding an organic substance to the denitrification tank.

FIG. 2 is a system diagram showing a second embodiment of the advanced treatment method for wastewater according to the present invention. The difference from the embodiment shown in FIG. 1 is that activated carbon is directly denitrified from an organic matter adsorption tank 6 3 is returned to the nitrification tank 4 through the activated carbon first return pipe 9, and the organic matter remaining on the activated carbon adsorbed by the activated carbon is oxidatively decomposed and then returned to the organic matter adsorption tank 3 through the activated carbon second return pipe 10. It is to introduce. This makes it possible to prevent breakthrough of the activated carbon.

FIG. 3 is a system diagram showing a third embodiment of the advanced treatment method for wastewater according to the present invention. In this embodiment, the reaction tanks on both sides of the nitrification tank are used as an organic matter adsorption tank and a denitrification tank by switching the flow direction of the wastewater. The wastewater is discharged from the activated carbon 1 through the first raw water introduction pipe 11 as indicated by the solid arrow.
It is introduced into the first activated carbon filling tank 13 filled with 2. In the first activated carbon filling tank 13, the adsorption of organic substances on the activated carbon 12 proceeds. The waste water from which the organic substances have been adsorbed and removed is then introduced into the nitrification tank 14, and the organic nitrogen and ammonia nitrogen in the waste water are oxidized to form nitrate nitrogen.
The nitrified wastewater is introduced into the second activated carbon filling tank 16 filled with activated carbon 15 and denitrified. The denitrified waste water is discharged from the first drain pipe 17. After a predetermined time,
The wastewater is introduced into the second activated carbon filling tank 16 through the second raw water introducing pipe 18 as indicated by the dotted line arrow by switching the valve. In this case, the adsorption of organic substances on the activated carbon 15 proceeds in the second activated carbon filling tank 16. The wastewater in which the organic substances have been adsorbed is then introduced into the nitrification tank 14, and the first
It is introduced into the activated carbon filling tank 13. First activated carbon filling tank 13
Then, denitrification proceeds using the organic matter adsorbed before switching the valve. The denitrified waste water is discharged from the second drain pipe 19.

According to the third embodiment, in order to achieve the same effect as that of the first embodiment, it is possible to reduce the power cost because the activated carbon is not transferred only by switching the valve, and the activated carbon is not transferred. The structure is simple because no activated carbon transfer device is required. However, also in the third embodiment, as in the case of the second embodiment, after a predetermined time has passed, the activated carbon in the first activated carbon filling tank or the second activated carbon filling tank is transferred to the nitrification tank 14 to cause adsorption. The organic matter remaining after being subjected to oxidative decomposition can be returned to the first activated carbon filling tank or the second activated carbon filling tank. This makes it possible to prevent breakthrough of the activated carbon.

[0014]

According to the present invention, even if a denitrification tank is installed after the nitrification tank, the organic matter in the wastewater can be utilized for denitrification, so that it is not necessary to add the organic matter for denitrification. The denitrification rate can be increased, and organic matter and nitrogen in wastewater can be efficiently removed.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of an advanced treatment method for wastewater according to the present invention.

FIG. 2 is a system diagram showing a second embodiment of the advanced treatment method for wastewater of the present invention.

FIG. 3 is a system diagram showing a third embodiment of the advanced treatment method for wastewater of the present invention.

[Explanation of symbols]

 1 Raw water introduction pipe 2 Activated carbon 3 Organic substance adsorption tank 4 Nitrification tank 5 Activated carbon transfer pipe 6 Denitrification tank 7 Drain pipe 8 Activated carbon return pipe 9 Activated carbon 1st return pipe 10 Activated carbon 2nd return pipe 11 1st Raw water introduction pipe 12 Activated carbon 13 1st Activated carbon filling tank 14 Nitrification tank 15 Activated carbon 16 Second activated carbon filling tank 17 First drainage pipe 18 Second raw water introduction pipe 19 Second drainage pipe

Claims (4)

[Claims] 1. A method for removing organic matter and nitrogen from wastewater containing organic matter and nitrogen by a nitrification step and then a denitrification step, wherein the organic matter in the wastewater is adsorbed on activated carbon in advance, and the activated carbon adsorbing the organic matter is denitrified. Introduced into the process,
A high-level treatment method for wastewater, which uses organic matter adsorbed on activated carbon as a hydrogen donor necessary for denitrification. 2. The advanced treatment method for wastewater according to claim 1, wherein the activated carbon used in the denitrification step is transferred to a nitrification step to oxidize and decompose residual organic matter, and then reused for adsorption of organic matter in wastewater. 3. A treatment tank comprising a first activated carbon tank, a nitrification tank and a second tank.
Characterized by arranging in an order of activated carbon tanks and switching the introduction of raw water from the first activated carbon tank side or the second activated carbon tank side at predetermined time intervals to sequentially perform adsorption of organic matter, nitrification treatment and denitrification treatment. Advanced wastewater treatment method. 4. The advanced treatment method of waste water according to claim 3, wherein the activated carbon used for the denitrification treatment is previously returned to the nitrification tank to oxidize and decompose the residual organic matter, and then returned to the first activated carbon tank or the second activated carbon tank. .