JPS586523B2 - emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating various emulsion wastewaters, such as water-soluble cutting oil wastewater or metal cleaning wastewater.

Recently, high-speed grinding methods have been widely used to improve machining accuracy and removal efficiency, and along with this, emulsion type, soluble type,
The usage of various water-soluble cutting oils such as solution type is increasing.

Since these cutting oils contain a large amount of surfactant as an emulsion stabilizer, the oils are in an emulsified state in wastewater, and their treatment is generally very difficult.

Furthermore, surfactants are often used in general factory wastewater, such as wastewater from metal washing tanks.

The present invention deals with oil, suspended solids, surfactants, COD components, etc. contained in the water-soluble cutting oil wastewater and metal washing wastewater, etc.
The present invention relates to a method for efficiently removing BOD components and the like.

Conventionally, methods for treating wastewater as described above include coagulation methods, adsorption methods, biological oxidation methods such as activated sludge methods, and methods that combine these methods.

Although each of these methods has its own advantages, it also has the following disadvantages.

In other words, the flocculation method uses an inorganic flocculant or a polymer flocculant to mainly remove oil, suspended matter, etc.
Further processing is required to remove the components.

Although adsorption methods using activated carbon adsorbents are effective in removing oil, it is often difficult to completely remove COD and BOD components.

Furthermore, biological treatment methods such as the activated sludge method require pretreatment by each of the above-mentioned methods, and it is difficult to remove COD components and there are many technical difficulties such as setting of conditions.

Furthermore, although an excellent removal effect can be obtained by combining the above methods, the maintenance and management of each process becomes complicated and the running cost increases significantly. However, there were various difficulties and inconveniences.

In view of the above facts, the present invention is characterized in that it combines an adsorption treatment method using activated clay or acid clay, etc., and an oxidation treatment method using hydrogen peroxide, and performs these two methods at the same pH and at approximately the same temperature. It is something.

Specifically, oil, surfactant, solid floating matter, COD component,
By adding an inorganic acid such as sulfuric acid to factory wastewater containing BOD components, etc., it is made acidic to a pH of approximately 1.5 to 4.5, and activated clay, acidic clay, etc. are added and stirred at a temperature of 60°C or higher. A process of separating emulsion-like oil and removing it by adsorption, a process of sedimentation and separation of the adsorbent sludge by standing still, and a process of converting the supernatant water into hydrogen peroxide solution at a pH range of 1.5 to 4.5 and a temperature of 80°C or higher. This method consists of a step of adding and stirring to perform oxidation, and a step of cooling the oxidized liquid through a heat exchanger, and then adding an alkali to neutralize it.

The present invention will be explained in detail below with reference to the drawings.

Emulsion oil water such as water-soluble cutting oil waste stored in the wastewater storage tank 1 enters the heat exchanger 3 by the pump 2, is heated to approximately 60° C., and then sent to the adsorption treatment tank 4.

The adsorption treatment tank 4 is equipped with a stirrer 5, a thermometer 6, a heater 7,
An H meter 8, a sulfuric acid storage tank 9, an activated clay tank 11, etc. are attached, and the emulsion oil/water is stirred by a stirrer 5 and heated by a heater 7.

This heating is detected by a thermometer 6 and is carried out so that the temperature of the treated water is within the set temperature.

Next, monitor with pH meter 8, and while stirring, valve 1
After opening the valve 12 and introducing sulfuric acid from the sulfuric acid storage tank 9 into the adsorption treatment tank 4 and setting the pH of the emulsion oil water to 1.5 to 4.5, open the valve 12 and add activated clay from the activated clay tank 11. .

The amount of activated clay to be added was calculated from the amount of oil contained in the water to be treated, which was measured in advance using an oil meter in the wastewater storage tank 1.

After that, stirring and heating are continued to keep the temperature constant and the oil is adsorbed to the clay. After stirring for a certain period of time, the treated water is left to stand for several hours to separate into supernatant water and clay sludge. The sludge is sent to the sludge storage tank 14 via the sludge tank 14.

The supernatant water is passed through a valve 15 and a pump 16 to an oxidation treatment tank 17.
Transfer to.

The required amount of hydrogen peroxide is determined from the supernatant water that has entered the oxidation treatment tank 17 using a COD meter 18 or the like, and hydrogen peroxide solution is added according to this value.

That is, the valve 19 is opened, hydrogen peroxide is introduced from the hydrogen peroxide tank 20, and stirring is continued by the stirrer 21 to carry out the oxidation reaction.

After an appropriate period of time has passed and the oxidation reaction is completed, the valve 22 is opened and the liquid in the oxidation treatment tank 17 is sent by the pump 23 to the heat exchanger 3 via the pipe 24, where it is mixed with the raw wastewater from the wastewater storage tank 1. After heat exchange, the temperature reaches room temperature, and then enters the neutralization treatment tank 25 through the pipe 24.

In the neutralization treatment tank 25, neutralization is carried out by stirring with the stirrer 26 and monitoring the pH with the pH meter 27 while opening the valve 28 and adding caustic soda from the caustic soda storage tank 29. When the reading reaches 6-8, stop adding caustic soda.

After the pH adjustment is completed, the water is allowed to stand for several hours and separated into supernatant water and precipitate, and then the supernatant water is discharged as treated water through valve 30 and pipe 31, and the precipitate that has settled at the bottom is discharged through valve 32 and pipe 33, respectively. The sludge is then sent to the sludge storage tank 14.

The sludge stored in the sludge storage tank 14 is neutralized, dehydrated, dried, and disposed of or reused.

The results of processing according to the above method are shown below.

As described above, the present invention combines a treatment method of decomposing an emulsion with an inorganic acid such as sulfuric acid and adsorption of oil with activated clay, etc., and a method of removing COD and BOD components with hydrogen peroxide, and performs the treatment under the same treatment conditions. This is a method of separating and oxidizing emulsion oil and water very efficiently.

Both the acid decomposition-adsorption treatment method in the first stage and the hydrogen peroxide treatment method in the second stage are effective methods having their own characteristics, and this method provides a method for more efficient treatment by combining both methods.

Therefore, in the first stage of acid decomposition-adsorption treatment, activated clay and acid clay are inexpensive and easily available, and the adsorption capacity can be increased by adding acids such as sulfuric acid. It has the characteristic that the adsorption effect does not change depending on the type of ion of the surfactant, that is, anion, nonion, or cation.

Furthermore, since the temperature is selected to be 60°C or higher, the adsorption rate is faster than at room temperature, and the sedimentation rate of white earth is faster than that of other flocculants, so there is an advantage that the treatment time can be shortened.

In addition, in the latter oxidation process, when performing the oxidation reaction with hydrogen peroxide, the pH and temperature of the wastewater are set to optimal conditions so that these conditions have a synergistic effect on the oxidation of the wastewater. There are characteristics.

That is, hydrogen peroxide is acidic and easily decomposed at high temperatures, but in this method, the pH of the treated wastewater is set to 1.5 to 4.5, which makes it difficult for hydrogen peroxide to decompose, and the temperature is set to 6, which makes it easy for decomposition to occur.
It was experimentally found that an effective and appropriate decomposition rate of hydrogen peroxide can be obtained by selecting a temperature of 0 to 100° C. and setting these contradictory conditions, and this is utilized.

This oxidation treatment using hydrogen peroxide has a great effect on removing COD components, and is also very effective in removing low concentration oil and BOD components that are generally difficult to remove with other treatment methods, so this process is Components that could not be removed in the previous adsorption step can be easily removed.

That is, by combining both methods, it is possible to remove even trace amounts of oil, COD components, BOD components, etc., extremely efficiently.

Furthermore, the method of the present invention provides the following effects by combining the two methods described above.

In other words, the acid added to break the emulsion has the effect of adjusting the pH of the oxidation process as it is, and since we have found a region where the optimal pH range and temperature range of the adsorption treatment process and the oxidation treatment process match, we have determined this, and this has allowed us to set the treatment conditions. It is economically advantageous because it is simple and easy to operate and the equipment required for it is also simple.

In addition, the alumina-silica in the activated clay or acid clay added in the adsorption treatment process acts as a catalyst for the decomposition of hydrogen peroxide in the oxidation treatment process, increasing the reaction rate and shortening the treatment time. It has the following effects.

[Brief explanation of the drawing]

The figure is a system diagram for explaining the method of the present invention. 1 is a wastewater storage tank, 3 is a heat exchanger, 4 is an adsorption treatment tank, 5, 2
1.26 is a stirrer, 6 is a thermometer, 7 is a heater, 8,2
7 is a pH meter, 17 is an oxidation treatment tank, 18 is a COD meter, and 25 is a neutralization treatment tank.

Claims (1)

[Claims] 1 In a method of treating industrial wastewater in which water and oil are emulsified, such as water-soluble cutting oil wastewater, an inorganic acid such as sulfuric acid is added to the emulsion oil-water to be treated to adjust the pH to 1.5 to 4.5.
Activated clay or acid clay is added and stirred at a temperature of 60 to 100°C to absorb oil, etc., and then the adsorbent sludge is separated by sedimentation, and the pH and temperature are adjusted to A method for treating emulsion oil water, which comprises performing oxidation treatment by adding hydrogen peroxide under certain conditions, neutralizing by adding alkali, separating precipitates, and then discharging supernatant water.