KR0145807B1 - Process for the treatment of waste water with hydrogen peroxide at elevated temperature and pressure - Google Patents

Abstract

The present invention activates hydrogen peroxide by using a heating apparatus to maintain the temperature of the reactor above 90 ° C., and sets the pressure in the reactor using a pressure pump to be higher than the vapor pressure maintained at the reaction temperature in the form of OH ^- radicals. The present invention provides a method for treating wastewater by reacting hydrogen peroxide with wastewater.

Description

Wastewater treatment method by hydrogen peroxide in warm pressurized state

1 is a schematic process diagram showing an oxidation treatment process of the present invention.

* Explanation of symbols for main parts of the drawings

1: wastewater storage tank 2, 7: transfer pump

3,6,9: Pipeline 4: Reactor

5: hydrogen peroxide reservoir 8: heating device

10: heat exchanger

The present invention relates to a wastewater purification method using hydrogen peroxide. More specifically, the present invention relates to a method for purifying wastewater by a simple process in which hydrogen peroxide is reacted with the wastewater under a pressurized temperature and pressure without using a separate additive.

Hydrogen peroxide is used in various fields as an oxidizing agent, a bleaching agent, and the like. Among them, hydrogen peroxide is widely used in wastewater treatment processes. As a wastewater treatment method using hydrogen peroxide, a so-called Fenton oxidation method that treats wastewater using iron sulfate as a catalyst and hydrogen peroxide as an oxidizing agent is widely used. In recent years, the so-called ultraviolet-hydrogen peroxide method, which irradiates ultraviolet rays after mixing hydrogen peroxide with wastewater, has also been used. Iron sulfate or ultraviolet light used in these methods acts to increase the reactivity by activating hydrogen peroxide with OH ^- radicals. p90 or below, Vereinigte Fachverlage (German); Chemical Process in Wastewater Treatment, G. Mattkock, WJEilbeck, 1987, P141 and below Ellis, Howard limited (USA)].

In the Fenton oxidation method described above, the amount of iron sulfate is determined by the concentration and degradability of pollutants in the wastewater. However, since thousands of ppm are usually required, the total operating cost according to the price of the product increases, and after such treatment is excessive. As sludge occurs, its treatment also remains a big problem. In addition, the ultraviolet-hydrogen peroxide method is not suitable for large-scale treatment because it consumes a lot of power primarily for the generation of ultraviolet rays, and in addition, hydrogen peroxide must remain in excess in order to expect proper wastewater treatment. It is discharged in a state. However, since hydrogen peroxide has reducibility at the same time, there is an additional burden of removing the residual hydrogen peroxide in a separate process in order to meet the discharge water quality standards.

Accordingly, the object of the present invention is to provide a method for treating wastewater by using hydrogen peroxide, by appropriately adjusting only the reaction temperature and pressure without using any other additives, such as the separate treatment of hydrogen peroxide, excessive operation costs, sludge treatment problems, and the like. It is to provide a wastewater purification method and apparatus which do not suffer from the disadvantages of other existing processes.

The object of the present invention, by maintaining the reactor temperature using a heating device with at least 90 ℃ activates the hydrogen peroxide, hydrogen peroxide, an OH by the set to be higher than the vapor pressure is maintained the pressure in the reactor at the reaction temperature using a pressure ^pump-radical It is achieved by a method of reacting the hydrogen peroxide and the wastewater by the presence of the form, and recovering heat from the hot effluent flowing out of the reactor to warm the influent.

In the method of the present invention, it is important to maintain the temperature and pressure of the reactor at a certain level, that is, above 90 ° C. and above the vapor pressure of the liquid formed at this temperature condition, since at the temperature below 90 ° C., the oxidizing power decreases rapidly and above the vapor pressure. Maintaining the pressure is intended to keep the material in the reactor in a liquid state to avoid non-uniform reactions that are generally extremely slow.

Thus, as the heating and pressurization apparatus essential to the method of the present invention, commercially available ones can be used, and examples thereof include an electric heating apparatus and a piston type pressure pump capable of temperature control.

Hereinafter, the present invention will be described in more detail with reference to FIG.

Waste water enters the reactor 4 along the conduit 3 by the transfer pump 2 from the waste water storage tank 1, and hydrogen peroxide is transferred from the hydrogen peroxide reservoir 5 to the conduit 6 as shown in FIG. 1. Through the feed pump 7 to the reactor 4 or from the reservoir 5 through the pipeline 6 to the reactor 4 by the transfer pump 7 or with the waste water already in the reservoir 1. After mixing, the wastewater may be introduced into the reactor 4 through the transfer pump 2 and the conduit 3 together with the waste water. Waste water exiting the reactor 4 after a suitable treatment time passes through a heat exchanger 10 equipped for heat recovery through a conduit 9 and then exits the apparatus of the present invention.

In the above process, hydrogen peroxide is activated and decomposed by the high temperature set in the reactor, but when the pressure in the reactor is set higher than the vapor pressure at the reactor temperature, the hydrogen peroxide is dissolved in water in the form of OH ^- radical or the like. Subsequently, the hydrogen peroxide dissolved in the water reacts with the substance to be removed in the waste water, and almost all of the injected hydrogen peroxide reacts quickly with the substance to be removed in the waste water. However, even if the reaction is left completely without the reaction, hydrogen peroxide does not remain in the purified water because it is immediately removed to the gaseous state due to the lowered air pressure outside the reactor. In addition, unlike other existing methods, in the method of the present invention, since no additional additives other than hydrogen peroxide are added, other solids are not generated in addition to the solids that were originally present in the wastewater, and the burden of the sludge treatment problem is not additionally generated. .

The present invention is described in more detail with reference to the following examples. However, these examples are only for illustrating the present invention, and the scope of the present invention is not limited by these examples.

Example 1

Wastewater with 35% hydrogen peroxide mixed with 135ml per liter of wastewater was mixed with wastewater with a phenol content of 10g per liter of water and introduced into the wastewater storage tank (1), and the wastewater was pumped using a transfer pump (2). Through 3), 7.5 liters per hour were continuously added to the reactor 4 having a capacity of 2.5 liters. Subsequently, the hydraulic retention time in the reactor was adjusted to 20 minutes, and the sample flowing out of the reactor 4 was taken every 20 minutes, and phenol decomposition was measured by colorimetric method. At this time, the internal temperature of the reactor 4 was maintained at 130 ℃, pressure was maintained at 4 atmospheres. The results showed that the phenol content in the treated wastewater was less than 0.1 mg per liter of wastewater, with a removal rate of at least 99%. In addition, when manganese dioxide was added to the treated wastewater, no bubbles were generated and it was proved that hydrogen peroxide was completely decomposed, and no precipitate was generated.

Example 2

A waste landfill leachate having a chemical oxygen demand of about 3800 ppm by the chromium method was introduced into the wastewater storage tank (1), and then the wastewater was passed through the conduit (3) using a transfer pump (2) (4 liters of reactor (4). ) And 5 liters per hour continuously. At the same time, hydrogen peroxide having a hydrogen peroxide content of 35% was introduced into the hydrogen peroxide storage tank (5), and then 36 ml per hour was continuously added to the reactor (4) using a transfer pump (7) to maintain hydraulic retention time in the reactor. After adjusting to about 30 minutes, the sample outflow from the reactor (4) was taken every 30 minutes and the chemical oxygen demand was measured by the chromium method. At this time, the internal temperature of the reactor 4 was maintained at 150 ℃, the pressure was maintained at 15 atm. As a result, the chemical oxygen demand by the chromium method in the treated wastewater was about 350 ppm per liter of wastewater, and the removal rate was about 91%. In addition, when manganese dioxide was added to the treated wastewater, it was proved that hydrogen peroxide was completely decomposed because no bubbles were generated, and the precipitate was generated about 45 ppm by the inorganic material originally contained in the leachate.

[Comparative Example]

After the same amount of hydrogen peroxide was added to the same leachate as in Example 2, 2500 ppm of iron sulfate was added, and the Fenton method was compared. As a result, the chemical oxygen demand of the treated wastewater was about 1300 ppm and the precipitate was about 2800 ppm. It was.

Claims (2)

By activating the hydrogen peroxide by maintaining the temperature of the wastewater reactor 4 above 90 ° C. using the heating device 8, and setting the pressure in the reactor 4 above the vapor pressure maintained at the reaction temperature using a pressure pump. Hydrogen peroxide is present in the form of OH ^- radicals to react hydrogen peroxide with waste water containing a substance oxidized by the hydrogen peroxide, and heat is recovered by the heat exchanger 10 from the hot effluent flowing out of the reactor 4. A method for treating wastewater with hydrogen peroxide, characterized in that the influent is warmed. A wastewater storage tank (1) for storing wastewater containing substances oxidized by hydrogen peroxide, a hydrogen peroxide storage tank (5) for storing hydrogen peroxide, and a wastewater reactor for reacting the wastewater with hydrogen peroxide to remove substances to be removed in the wastewater (4). ), A heating device 8 for heating the reaction temperature of the reactor 4 to 90 ° C. or higher in order to activate the hydrogen peroxide in the wastewater reactor 4, and the pressure in the wastewater reactor 4 of the liquid formed at this temperature. A pressurized pump for pressurizing at a reaction pressure above the vapor pressure and a heat exchanger 10 for recovering heat from the hot effluent flowing out of the reactor are provided. Wastewater Treatment Reactor.