JPS587359B2 - Denitrification equipment for water treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a denitrification device for water treatment that simultaneously performs a reaction in which a nitrogen compound is oxidized and then reduced to be removed as nitrogen gas. The purpose is to make it easy and reliable.

Next, embodiments of the present invention will be described in detail based on the drawings.

A supply pipe 1 for water to be treated containing a nitrogen compound is connected to one longitudinal end of a treatment tank 2, and a pipe 3 for taking out denitrified water by overflow is connected to the other end of the tank 2.
A partition wall 4 communicating with the inside of the processing tank 2 at its bottom...
are provided at intervals in the longitudinal direction of the tank 2 to form a plurality of compartment spaces 5 connected in series inside the tank 2,
A pipe 6 equipped with an upward gas discharge nozzle is disposed in each of the divided spaces 5 on the bottom side and near one side wall, and a branch supply pipe 8 from an oxygen gas-containing air supply device 7 is provided. ... is connected to the husband and wife of the pipe 6, whereby the nitrogen-containing water is swirled in one direction in the tank by supplying oxygen-containing gas, and the nitrogen-containing water is taken out by taking out the treated water from the take-out pipe 3. The nitrogen-containing water is made to flow toward the third side, and oxygen gas is dissolved in the nitrogen-containing water flowing in a swirling manner.

A valve 9 for controlling the supply amount of oxygen-containing gas is installed in each of the supply pipes 8, and each compartment space 5...
The oxidation-reduction potential of the nitrogen-containing water in the tank (
Hereinafter, it will be abbreviated as ORP.

), and a control device 11 for the valve 9 based on the detected value from the oxidation-reduction potential detection device 10.
The supply amount of the oxygen-containing gas is adjusted by the oxidation-reduction potential detection device 10 to automatically maintain the ORP detection value within a set range.

A pipe 12 for returning and supplying the treated water from the take-out pipe 3 is connected to the first, second and third compartment spaces 5..., and a valve 13 for controlling the amount of returned treated water is connected to each supply pipe 12. interposed, and in each compartment space 5, the hydrogen index (hereinafter abbreviated as pH) of the nitrogen-containing water in the tank is determined.

) is provided, and a hydrogen index detection device 14 is provided.
The control device 15 of the control valve 13 adjusts the amount of returned treated water based on the value detected by the hydrogen index detector 14, and the pH value detected by the hydrogen index detector 14 is automatically maintained within a set range. .

A net-like body 16 is stretched in each of the divided spaces 5 to form an upward flow path for the air supplied from the pipe 6 and to form a gap with the bottom wall of the tank. A large number of plate-shaped or cylindrical carriers made of plastic or the like are filled in the divided area formed by the net-like body 16 to maximize the area in contact with the liquid per apparent volume, and activated sludge is attached to the carriers. Then, under conditions where the control devices 11 and 15 automatically maintain the ORP and pH of the nitrogen-containing water within the set range, the nitrogen-containing water is repeatedly brought into contact with the packed bed of the carrier to which the activated sludge is adhered. During this time, the activated sludge adhering to the same carrier causes both the oxidation of the nitrogen content and the reduction of the nitrogen oxides to proceed at the same time, so that the nitrogen additives in the water are surely and easily removed from the water as nitrogen gas. There is.

In other words, the activated sludge adhering to the packed carrier causes an oxidation reaction to occur in the activated sludge layer under aerobic conditions on the liquid phase side, and reduction in the activated sludge layer under anaerobic conditions on the carrier side. By placing the ORP level of the nitrogen-containing water under favorable conditions for the oxidation reaction, sufficient oxidation treatment of the nitrogen-containing water is promoted, and subsequent good denitrification treatment can be performed. Of course, ORP
Even if the level is low, the relative contact efficiency of water with the packed fixed bed of carrier is high, so the ORP level in the activated sludge layer part on the liquid phase side is substantially high, resulting in a favorable condition. Oxidation treatment in which an oxidation reaction is carried out and activated sludge is simply allowed to flow freely requires very strict control of ORP, but compared to this, the control range of ORP can be significantly expanded, and this is an extremely advantageous state in terms of control. An oxidation reaction treatment can be performed.

Fluctuations in pH level have a negative effect on denitrification treatment, but by maintaining the pH level within the set range by returning treated water, the denitrification treatment using activated sludge described above can be carried out reliably and easily. Moreover, since the pH level and ORP level are automatically maintained as set, appropriate treatment can be performed as desired without any manual operation.

Note that the nitrogen-containing water is wastewater leached from a garbage landfill, and the ORP in the first compartment space 5 is set to -50 to ±0 mv.
and pH 7. 0 to 7. 5, the ORP in the second compartment space 5 is set to ±5.0 mv, and the pH is set to 7.0 mv.
0 to 8.0, the ORP in the third compartment space 5 is set to +50 to +100 mV and the pH is set to 6.5 to 7.5, and the ORP in the fourth compartment space 5 is set to +100 mV or more and the pH is set to 6. ．． 5-7. When it was set to 0, sufficient denitrification results were obtained as desired.

In addition, when returning treated water for pH adjustment, stable and efficient treatment was possible when the amount of nitrogen-containing water supplied was controlled within the range of 0.5 to 5 times the supplied amount, which is preferable. sets that range as the control range.

Note that there is no limit to the number of divisions in the tank 2 by the partition wall 4, and it may be done without partitioning, and when partitioning is done, each partition space 5 may be divided separately or in a predetermined manner. Detection devices 10, 14 and automatic control devices 11, 15 may be selectively attached to the device.

In addition, although the carrier is a packed fixed bed, it may also be a fluidized bed that convects with nitrogen-containing water in a tank, or it may be configured to adjust the bed thickness. By adhering the activated sludge to a carrier in the form of a fluidized bed, there is no need to return the activated sludge unlike the type in which activated sludge is suspended, making operation easier and reducing running costs.

In summary, the denitrification device for water treatment according to the present invention accommodates a carrier to which activated sludge is attached in a tank, is provided with a device for detecting the oxidation-reduction potential and hydrogen index of the nitrogen-containing water in the tank, and A device is provided for automatically controlling the amount of oxygen-containing gas supplied to the nitrogen-containing water in the tank in order to maintain the detected value within a set range based on the detected value from the reduction potential detecting device, and the hydrogen index detecting device The apparatus is characterized in that a device is provided for automatically controlling the amount of treated water returned to the tank based on the detected value from the tank in order to maintain the detected value within a set range.

That is, by adhering activated sludge to a carrier and bringing it into contact with nitrogen-containing water, the control range of redox potential can be significantly expanded, and the redox potential and hydrogen index can be maintained at a level sufficient to maintain the desired reaction. By automatically setting the conditions, it is possible to perform sufficient oxidation treatment with easy control of the oxidation-reduction potential in particular, and to promote good denitrification treatment by controlling the hydrogen index. On top of that,
This eliminates the need to return activated sludge, which was previously required, and simplifies the treatment process.

[Brief explanation of the drawing]

The drawings show an embodiment of the denitrification device for water treatment according to the present invention,
FIG. 1 is an overall longitudinal sectional side view, and FIG. 2 is a sectional view taken along the line ■--■ in FIG. 1. 2...tank, 5...compartment space, 10...oxidation-reduction potential detection device, 11...oxygen-containing gas supply amount automatic control device, 14
...Hydrogen index detection device, 15...Automatic control device for the amount of returned treated water.

Claims (1)

[Scope of Claims] 1. A carrier to which activated sludge is attached is housed in a tank 2, and devices 10 and 14 are provided for detecting the oxidation-reduction potential and hydrogen index of the nitrogen-containing water in the tank 2, and the oxidation-reduction A device 11 is provided that automatically controls the amount of oxygen-containing gas supplied to the nitrogen-containing water in the tank 2 based on the detected value from the potential detection device 10 in order to maintain the detected value within a set range, and the hydrogen index The dewatering device for water treatment is characterized in that it is equipped with a device 15 that automatically controls the amount of treated water returned to the tank 2 based on the detected value from the detection device 14 in order to maintain the detected value within a set range. Nitrogen equipment. 2 A plurality of compartment spaces 5 connected in series are formed inside the tank 2, and both the detection devices 10 and 14 and both automatic control devices 11 and 15 are connected to each compartment space 5. The denitrification device for water treatment according to claim 1, characterized in that it is separately attached.