JPS6336894A - Treatment method for hydrazine-containing wastewater - Google Patents

Abstract

PURPOSE:To reduce a necessary amount of a catalyst by contacting the exhaust water contg. hydrazine with an air high in the oxygen concn. in the presence of the catalyst, thereby decomposing hydrazine with a short contacting time of the catalyst. CONSTITUTION:The exhaust water contg. hydrazine is fed to an area 3 equipped with the catalyst 4 such as Pd, through the pipe 5, and at the same time, air is fed to said area 3 through the pipe 13 whereby the hydrazine contd. in the exhaust water contacts with the air in the presence of the catalyst to decompose the hydrazine and to purify the exhaust water so as to suit for the standard value of exhaust water contg. hydrazine. And, the oxygen gas is fed to said air from an oxygen supplying apparatus 15 to increase the oxygen concn. in said air, and the hydrazine contacts with the air high in the oxygen concn. in the presence of the catalyst at the area 3. As the result, the hydrazine can be decomposed with a short contact time of the catalyst, thereby enabling to remarkably reduce the necessary amount of the catalyst, and to obtain a large economical effect.

Description

[Detailed description of the invention] The present invention aims to solve the following problems.

(Industrial Application Field) This invention relates to a method for treating hydrazine-containing wastewater.

(Prior Art) When a boiler is not used in a thermal or nuclear power plant, water containing hydrazine is filled in the boiler to prevent rust. When the boiler is restarted, the water containing the hydrazine is discharged. The amount is, for example, 1,000 to several tens of thousands of tons per batch. Since the discharged water, ie, the hydrazine-containing wastewater, does not meet the wastewater standards as it is, it is treated in a treatment facility as shown in FIG. 3, for example. That is, in FIG. 3, l is a treatment layer, which consists of a receiving tank 2 and an aeration layer 3 provided above it. The inside of the aeration layer 3 is a region for catalyst contact, and a catalyst 4 is provided there.

Palladium is used as the catalyst, and for example, metal mesh-like catalysts are stacked together. 5 is a receiving pipe for untreated wastewater containing hydrazine, 6 is a delivery pipe for treated wastewater, and 7 is a gas delivery port. 10 is an air intake port,
11 is a blower, 12 is a valve, 13 is an air supply pipe, and a plurality of nozzles 14 are provided. In such equipment, a hydrazine-containing material (e.g.
00 ppm) The waste water is introduced into the receiving tank 2 in the treatment tank 1, and the waste water reaches the aeration layer 3. On the other hand, blower 11
The air taken in from the air intake port 10 by the operation of
The air passes through the pulp 12 and reaches the air-feeding vibrator 13, where it is ejected from a nozzle 14 as a large number of bubbles. The air reaches the aeration 4j3. The inside of the aeration layer 3 is aerated with the air, and the hydrazine in the hydrazine-containing wastewater comes into contact with the catalyst 4 together with the air, and the hydrazine is decomposed as shown in the following formula.

NZH4+ 02-N z + 2 Ht O The wastewater in which hydrazine has been decomposed as described above and has reached a state that meets the wastewater standard values, that is, the treated wastewater, is discharged from the delivery vibro to the sea or rivers, or is reused. It gets passed around. Excess air or nitrogen produced by decomposition is also delivered through the gas delivery lower. When hydrazine is decomposed as described above, the decomposition rate is influenced by temperature, pH 1 oxygen concentration, etc., and among these, oxygen 4 degrees has a particularly large influence. Therefore, when oxygen in the air is used to decompose the hydrazine, as shown by the solid line graph in Figure 2, in the region of hydrazine concentration exceeding about 60 ppm, the concentration of oxygen in the air becomes reactive. is the rate-limiting factor.

For this reason, as is clear from the graph, the contact time between the catalyst and the hydrazine-containing wastewater must be increased (t2), and for that purpose a large amount of catalyst must be used. However, palladium used as this catalyst is a precious metal and is very expensive, so there is a problem in that it requires an extremely large amount of cost.

(Problems to be Solved by the Invention) This invention eliminates the above conventional problems and can decompose the hydrazine in a short contact time with a catalyst, and as a result, the amount of catalyst required can be extremely reduced. The present invention aims to provide a method for treating hydrazine-containing wastewater that can achieve great economic effects.

The configuration of the present invention is as follows.

(Means for Solving the Problems) The present invention takes the measures as described in the claims above, and its effects are as follows.

(Operation) Hydrazine-containing waste water is passed through an area provided with a catalyst. Air enriched with oxygen is also passed through the above region. In the above region, hydrazine in the waste water comes into contact with the catalyst together with air with increased oxygen concentration, and the hydrazine is decomposed.

(Embodiment) Hereinafter, a description will be given of FIG. 1, which shows an embodiment of the present application. The same reference numerals as in FIG. 3 represent functionally equivalent parts, and a detailed explanation of these parts will be omitted.

In FIG. 1, reference numeral 15 denotes an oxygen supply device, which is connected to the air supply vibrator 13 via a valve 16.

With the above configuration, when treating hydrazine-containing wastewater, oxygen sent from the oxygen supply device 15 is added to the air sent from the air intake port 10 to the vibe 13. Therefore, the oxygen concentration in the air without being blown out from the nozzle 13 is higher than the oxygen concentration in normal air. Therefore, when hydrazine comes into contact with the catalyst together with the air in the aeration layer 3 and is decomposed, the oxygen concentration in the air is not the rate-limiting factor for the decomposition of hydrazine (as shown by the broken line in Figure 2). The hydrazine in the waste water is sufficiently decomposed within a very short contact time (tI) with the catalyst.

The time is, for example, 172 to 1/3 that of the conventional method. Therefore, the amount of catalyst 4 in the aeration layer is 1/1 compared to the conventional device.
2 to 1/3 is sufficient. This has a large economic effect and aeration f! This has the effect of making the size of 3 smaller than before. The degree to which the oxygen concentration is increased is preferably determined depending on the hydrazine concentration in the waste water so that the oxygen concentration does not become rate-determining for the decomposition reaction.

(Effects of the Invention) As described above, in the present invention, when purifying hydrazine-containing wastewater, the hydrazine in the wastewater is brought into contact with a catalyst together with air to be decomposed, and the hydrazine-containing wastewater meets the wastewater standard values. It can even purify wastewater.
It has the effect of making it possible to release it into rivers or rivers or to make it reusable.

Furthermore, in the above case, by adding oxygen to the air to increase its oxygen concentration, in the above region,
Since the hydrazine is brought into contact with the catalyst together with air having an increased oxygen concentration, it has the advantage that the hydrazine can be decomposed in a short contact time with the catalyst. This means that
The amount of extremely expensive catalyst required is very small (e.g. halved compared to conventional methods), and as mentioned above, a very large economic effect can be obtained with only a small cost for oxygen supply. It has revolutionary usefulness.

[Brief explanation of drawings]

The drawings show examples of the present application, and Fig. 1 is a system diagram of treatment equipment for hydrazine-containing wastewater, Fig. 2 is a graph showing the relationship between the contact time of the catalyst and hydrazine-containing wastewater and hydrazine concentration, and Fig. Figure 3 is a system diagram of conventional processing equipment. 4...Catalyst, 5...Hydrazine-containing wastewater reception pipe, 13...Air supply pipe. Figure 1-Figure 2 Contact time between Rin catalyst and hydrazine-containing wastewater Figure 3

Claims (1)

[Claims] By passing the hydrazine-containing wastewater through an area equipped with a catalyst and also passing air through the area, the hydrazine in the wastewater is brought into contact with the catalyst together with the air and decomposed, and the hydrazine-containing wastewater is adjusted to the wastewater standards. In the treatment method for hydrazine-containing wastewater, which purifies the wastewater to a level that meets the above-mentioned values, by adding oxygen to the air to increase its oxygen concentration, in the above-mentioned region, the hydrazine is purified along with the air with increased oxygen concentration. A method for treating hydrazine-containing wastewater, which comprises bringing the hydrazine into contact with a catalyst and decomposing the hydrazine in a short contact time with the catalyst.