JPH07204686A - Method and apparatus for nitration-denitrification using biological membrane - Google Patents

Abstract

PURPOSE:To downsize equipment and to improve the recovery ratio of treated water. CONSTITUTION:Raw water is supplied from a raw water supply part 11 at the upper end of a nitrification-denitrification biological membrane filter bed 3 in which an aerobic biological membrane filter bed 1 is installed on the upper stage and an anaerobic biological membrane filter bed 2 is installed on the lower stage to nitrify MH4-N. The nitrified liquid, after being mixed with a hydrogen donor, is denitrified in the lower stage. The anaerobically treated water is returned to the upper end of the nitrification-denitrification biological membrane filter bed 1 by a circulating pump 6 and discharged as treated water from a treated water discharge part 12 placed between the upper and lower stages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrification denitrification method and apparatus utilizing a biofilm used for treating sewage and the like.

[0002]

2. Description of the Related Art As a conventional nitrification denitrification method utilizing a biofilm, as shown in FIG.
The raw water is supplied from the upper end of the nitrifying / denitrifying biofilm filter bed 3 provided with the anaerobic biofilm filter bed 2 in the lower part, and CH ₃ OH is added as a hydrogen donor to the nitrification solution nitrified in the upper part while the lower part is added. There is a method to denitrify.

However, in such a conventional method, the added CH ₃ OH may not be used at all during the denitrification reaction and may flow out into the treated water taken out from the lower end of the nitrifying / denitrifying biofilm filter bed 3. In addition, a large amount of SS is generated by the addition of CH ₃ OH, and the SS of treated water becomes high. Therefore, as shown in FIG. 3, it is necessary to install a re-aeration tank 4 after the nitrification denitrification biofilm filter bed 3 to remove residual CH ₃ OH and SS. Therefore, there are problems that the equipment becomes large and that the recovery rate of the treated water decreases because the re-aeration tank 4 also needs to be cleaned.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, can downsize the equipment, and can improve the recovery rate of treated water. It has been completed to provide a denitrification method and a device therefor.

[0005]

A method for nitrifying and denitrifying using a biofilm of the present invention, which has been made to solve the above problems, comprises an aerobic biofilm filter in the upper stage and an anaerobic biofilm filter in the lower stage. Raw water is supplied from the upper end of the nitrifying denitrification biofilm filter bed provided with a bed, while the hydrogen donor is added to the nitrification solution nitrified in the upper stage, while denitrifying in the lower stage, and the resulting anaerobic treated water is nitrified. It is characterized in that it is returned to the upper end of the denitrification biomembrane filter and taken out as treated water from an intermediate position between the upper and lower stages. Further, the nitrification denitrification apparatus utilizing the biofilm of the present invention made to solve the above-mentioned problems is a nitrification denitrification organism having an aerobic biofilm filter bed in the upper stage and an anaerobic biofilm filter bed in the lower stage. A raw water supply unit is installed at the upper end of the membrane filter bed, and a circulation pump that returns the anaerobic treated water taken out from the lower end of the anaerobic biomembrane filter bed to the upper end of the nitrifying / denitrifying biomembrane filter bed is provided. It is characterized in that a hydrogen donor addition section and a treated water extraction section are provided at an intermediate position in the lower stage.

[0006]

According to the present invention, the anaerobic treated water taken out from the lower end of the anaerobic biological membrane filter bed is returned to the upper end of the nitrifying denitrifying biological membrane filter bed and taken out as treated water from the intermediate position between the upper stage and the lower stage. Therefore, CH ₃ OH and SS contained in the anaerobic treated water (treated water in the conventional method) taken out from the lower end of the anaerobic biofilm filter bed are removed by the upper aerobic biofilter bed. This eliminates the need for a re-aeration tank for removing CH ₃ OH and SS, which is required in the past, and makes it possible to downsize equipment.
In addition, the recovery rate of treated water can be improved. In addition, according to the present invention, there is an advantage that the denitrification rate can be controlled by changing the circulation rate of the anaerobic treated water.

[0007]

The present invention will be described below in more detail with reference to the illustrated embodiments. FIG. 1 shows a first embodiment of the present invention, and 3 is a nitrifying denitrification consisting of an upper aerobic biofilm filter bed 1 and a lower anaerobic biofilm filter bed 2 as in the conventional example. It is a biomembrane filter. The aerobic biofilm filter bed 1 has nitrifying bacteria (nitrite bacteria and nitric acid bacteria) supported on the surface of a carrier, and is kept aerobic by the air supplied from the air diffuser 5 below the carrier. There is. This aerobic biomembrane filter bed 1
It has the effect of nitrifying NH ₄ -N into NO ₂ -N and NO ₃ -N by the action of nitrifying bacteria. The lower anaerobic biofilm filter bed 2 has a denitrifying bacterium supported on the surface of a carrier, and is supplied from a hydrogen donor adding section 10 provided at an intermediate position between the upper and lower stages.
Using CH ₃ OH, etc. as a hydrogen donor, NO ₂ -N and
Denitrize NO ₃ -N.

In the present invention, raw water is supplied from the raw water supply unit 11 at the upper end of the aerobic biofilm filter bed 1 and a hydrogen donor is added to the nitrification solution nitrified by the aerobic biofilm filter bed 1 in the upper stage. While adding, denitrification is performed in the lower anaerobic biofilm filter bed 2. Then, the entire amount of the anaerobic treated water taken out from the lower end of the anaerobic biofilm filter bed 2 is converted by the circulation pump 6 into a nitrifying / denitrifying biofilm filter bed 1.
Return to the top of. Then, the treated water is taken out from the treated water take-out section 12 provided at an intermediate position between the upper stage and the lower stage.

As described above, in the present invention, the entire amount of the anaerobic treated water is returned to the raw water supply section 11 at the upper end of the aerobic biofilm filter bed 1, so that the hydrogen donor not used in the anaerobic biofilm filter bed 2 is supplied. CH ₃ OH is aerated in the aerobic biofilm filter bed 1 and decomposed. In addition, SS generated by the addition of the hydrogen donor is also completely removed by filtering with the aerobic biofilm filter bed 1. Therefore, the conventional re-aeration tank 4 is replaced with the nitrifying / denitrifying biofilm filter 3
It is not necessary to provide it in the latter stage, and there is an advantage that the equipment can be downsized and the recovery rate of treated water can be improved. Further, the denitrification rate can be controlled by changing the circulation rate of the anaerobic treated water.

FIG. 2 shows a second embodiment of the present invention. A raw water flow rate sensor 7 is attached to a raw water supply section 11 and a treated water flow rate sensor 8 is attached to a treated water extraction section 12, and their outputs are provided. The control device 9 controls the circulation pump 6 in accordance with the above. With this configuration, there is an advantage that the circulation rate of the anaerobic treated water can be automatically controlled and the denitrification rate can be controlled.

[0011]

As described above, according to the present invention, the conventional re-aeration tank is unnecessary, so that the equipment can be downsized, and the cleaning of the re-aeration tank is also unnecessary. The recovery rate of water can be improved. Further, according to the present invention, there is an advantage that the denitrification rate can be controlled.
Moreover, it was confirmed that 100% of NH ₄ -N in raw water can be removed and TN (total nitrogen) of 50% or more can be removed.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a first embodiment of the present invention.

FIG. 2 is a flow sheet showing a second embodiment of the present invention.

FIG. 3 is a flow sheet showing a conventional example.

[Explanation of symbols]

1 aerobic biofilm filter bed, 2 anaerobic biofilm filter bed, 3 nitrification denitrification biofilm filter bed, 4 re-aeration tank, 5 aeration device, 6 circulation pump, 7 raw water flow sensor, 8 treated water flow sensor, 9 control device, 10 hydrogen donor addition part, 11 raw water supply part, 12 treated water extraction part

Claims (3)

[Claims] 1. Raw water is supplied from the upper end of a nitrifying denitrification biofilm filter bed having an aerobic biofilm filter bed in the upper stage and an anaerobic biofilm filter bed in the lower stage, and hydrogen is added to the nitrification solution nitrified in the upper stage. It is characterized by denitrifying while adding a donor, returning the obtained anaerobic treated water to the upper end of the nitrifying denitrifying biofilm filter, and taking out as treated water from an intermediate position between the upper and lower stages. A nitrification denitrification method using a biofilm. 2. A raw water supply unit is provided at the upper end of the nitrifying / denitrifying biofilm filter having an aerobic biofilter on the upper side and an anaerobic biofilter on the lower side. A circulation pump was provided to return the anaerobic treated water taken out from the lower end to the upper end of the nitrifying denitrification biomembrane filter bed, and a hydrogen donor addition part and a treated water take-out part were provided at an intermediate position between the upper and lower stages. A nitrification denitrification device using a biofilm. 3. The nitrification denitrification apparatus using a biofilm according to claim 2, wherein a flow rate sensor is attached to each of the raw water supply section and the treated water extraction section, and a control device for controlling the circulation pump is provided by the outputs of the flow rate sensors.