JPS58166985A - Treatment of waste water containing organic material - Google Patents

Abstract

PURPOSE:To maintain high efficiency of the treatment up to the final treatment by adding ozone and hydrogen peroxide to waste water contg. materials, and adding salts contg. metallic ions which form insoluble or hardly soluble salts with carbonate radical. CONSTITUTION:Waste water contg. org. materials is supplied from a raw water tank 6 to an ozone reaction tank 2 by a pump 9. Prescribed amts. of salts contg. metallic ions that form salts insoluble or hardly soluble salts with carbonate radical, hydrogen peroxide and acidic or alkaline agent is fed into the waste water supplied into the tank 2 with pumps 12, 8, 7 respectively in the mid-way of said supply. There are alkaline earth salts such as Ca, Sr and Ba as the salts cont. metallic ions which form insoluble or hardly soluble salt with carbonate radical by reacting with said radicals. The air or oxygen contg. ozone formed with an ozone generator 1 is made into fine bubble by a diffuser 3, which ascends in the water to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating organic matter-containing wastewater using ozone and hydrogen peroxide.

Ozone is a powerful oxidizing agent produced by silent electrical discharge using air or oxygen as a raw material. With the development of large ozone generators and improvements in their performance, ozone has become available for industrial use and is now put into practical use in various wastewater treatments. Ozone is used to decolorize dye factory wastewater and remove phenol, cyan, etc.

It is used to treat wastewater containing organic matter, such as decolorizing treated human waste water. These methods utilize the chemical property of ozone that easily breaks unsaturated bonds in various organic substances.

On the other hand, in recent years, the need for stronger environmental protection measures and the reuse of wastewater has increased, and more advanced treatment has become necessary for a variety of wastewater than ever before, as well as total COD (chemical oxygen demand) regulations. There is a particular need for the development of effective COD removal techniques based on COD.

Under these circumstances, attempts have been made to remove COD using ozone, and this method is being put into practice in some cases.

It is well known that there are many COD components that do not react at all or hardly with ozone, and that there are many cases in which COD cannot be removed using ozone alone.

In order to eliminate such application limits of ozone, a hydrogen peroxide addition ozone treatment method has been proposed.

Figure 1 is a system diagram showing this type of conventional processing method.
In the figure, (1) is an ozone generator, (2) is an ozone reaction tank, (3) is a diffuser for ozone dispersion, +
41 is an acid or alkali agent storage tank for one adjustment.

(5) is hydrogen peroxide storage tank, (6) is raw water tank, (7) is acid or alkali injection pump, (8) is hydrogen peroxide injection pump, (9) is raw water supply pump, Ql is exhaust ozone decomposition It is a vessel.

In the treatment method shown in Figure 1, raw water is supplied from the raw water tank (6) to the ozone reaction tank (2) by a pump (9).

On the way, a predetermined amount of hydrogen peroxide and an acid or alkali agent are pumped into the reaction tank (2) by pumps (8) and (7), respectively.
) The amount of wax acid or alkaline agent injected into the raw water supplied to the reactor (2) is set so that - of the water to be treated in one reaction tank (2) is from 6 to 8. Ozone-containing air or oxygen (hereinafter referred to as ozone-containing air) generated by the ozone generator (1) becomes fine bubbles in the diffuser (3) and rises in the water to be treated. During this time.

Most of the ozone in the bubbles is consumed by the reaction, and a portion is exhausted. Exhaust ozone is removed by an exhaust ozone decomposer Ql and then released into the atmosphere. Raw water that is continuously supplied to the ozone reaction tank (2) is treated by reacting with the ozone and is continuously taken out from the bottom of the first reaction tank (2) as treated water. The above is a continuous treatment method, but in addition to this, there is also a semi-batch treatment in which raw water is first filled into the reaction tank (2), and then hydrogen peroxide and an acid or alkali agent are injected into the reaction tank (2) while being treated with ozone. The same effect can be obtained by law.

Figure 2 shows an aqueous solution of sodium acetate, which is one of the oxidation-resistant substances, using the treatment method shown in Figure 1.

The amount of hydrogen peroxide added was varied between 0 and 50 drops/l.

It is a curve diagram showing the amount of TOC (total organic carbon) removed when ozone treatment is performed near neutrality. Furthermore, TOC before processing
is 4oq/l. From Figure 2, it can be seen that when ozone treatment is performed without adding hydrogen peroxide, almost no TOC is removed, whereas when hydrogen peroxide is added, TOC is removed. The amount of TOC removed increases as the amount of hydrogen peroxide added increases. In this way, organic substances that could not be removed at all by conventional ozone treatment can now be removed by ozone treatment combined with hydrogen peroxide.An example of the treatment results of this method is shown in Table 15.
Table 1 shows the results of treatment by adding certain amounts of hydrogen peroxide and ozone to various organic matter-containing aqueous solutions having a TOC of about 40 Iv/l and 11 degrees. T for any organic matter
OC has been removed and TOC and TOD
(Total oxygen demand) Amount of ozone required to remove 1 weight unit (
Δ03/Δ'I"oc and ΔOs/ΔTOD) are about 10 and 3 weight units, respectively, which indicates high ozone utilization efficiency. Also, hydrogen peroxide consumption is small, about 1/10 of ozone consumption. be.

As explained above, the hydrogen peroxide addition ozonation method is an extremely effective method for removing organic matter, but it has the following drawbacks. If the raw wastewater contains a large amount of carbonate radicals such as carbonate ions or bicarbonate ions, ozone and hydrogen peroxide are wasted and the above-mentioned Δ03
/ΔTOC1Δot O! /ΔTOC becomes large, making it impossible to perform economical organic matter treatment. The fJc3 diagram shows an aqueous sodium acetate solution to which bicarbonate ions have been added in the form of sodium bicarbonate, and hydrogen peroxide is added to the aqueous solution at pH 7.5. The removal performance of acetate ions when
C.

It is a diagram evaluated by ΔHtoz/ΔTOC. The results clearly show that, as mentioned above, the coexistence of monobicarbonate ions deteriorates the organic matter removal effect of ozone and hydrogen peroxide.

Furthermore, even if the raw wastewater does not contain any carbonate radicals, if it contains a high concentration of organic matter, carbonate radicals will be generated during the oxidation process of the organic matter, which will similarly impair the effectiveness of the organic matter treatment.

The present invention was made in order to eliminate such drawbacks of the conventional hydrogen peroxide addition ozonation method, and involves adding a metal ion-containing salt that forms an insoluble or poorly soluble salt with carbonate radicals to raw wastewater. ? From this.

The object of the present invention is to provide a method for treating organic matter-containing wastewater that can efficiently treat organic matter.

FIG. 4 is a system diagram showing a processing method according to an embodiment of the present invention. In FIG. 1, (1) to 01 indicate the same or equivalent parts as in FIG. 1. 011 is a metal salt bath liquid storage tank in which a solution of a metal ion-containing salt that forms an insoluble or slightly soluble salt with a carbonate radical is stored. 02 is a metal salt solution injection pump. The treatment method shown in FIG. 4 is almost the same as that shown in FIG. 1, except that a metal salt is added to the raw water from a pump (12, metal salt solution storage tank αl).

When the carbonate radicals contained in the raw water have an ionic form, the efficiency of the ozonation treatment with hydrogen peroxide is reduced as described above, but the dissolved carbonate radicals become suspended as insoluble salts. Then, there will be no interference at all. Therefore, in the present invention, by adding a metal ion-containing salt 1, for example, a salt containing alkaline earth metal ions such as calcium, strontium, and barium, which reacts with existing carbonate roots to form an insoluble or poorly soluble salt, carbonate roots remove the interference of
Maintain high efficiency of hydrogen peroxide addition ozonation treatment.

The solubility of carbonate of Shio calcium, strotium and barium is 1.5 x 10-' mol/j (
25°C), 7.5X10-'mol/# (18°C) and 1. I x 10-'mol/1 (18°C). Therefore, as is clear from FIG. 3, by producing these carbonates, the disturbance caused by the remaining dissolved carbonate radicals can be reduced to a negligible extent.

Furthermore, the carbonate radicals produced by the treatment of organic matter will form insoluble salts if appropriate metal ions are added, so that the effects of hydrogen peroxide and ozone treatment can be maintained under ideal conditions. Also, points to be noted when applying the present invention.

When the amount of metal ions added is insufficient, even if an insoluble carbonate is formed, it may change to monobicarbonate and become soluble again. Therefore, the amount of metal ions added must be such that the total amount of carbonate radicals contained in the raw water and carbonate radicals generated during the treatment process is the insoluble salt. That is, it is sufficient to implant an amount of metal ions equivalent to the total amount of carbon in the raw water.

Therefore, by setting the amount of the metal ion-containing salt added to be at least equimolar to the sum of inorganic carbon and organic carbon contained in the wastewater, the efficiency of the hydrogen peroxide addition ozone treatment can be maintained at a high level.

In this case, a means for measuring the total carbon content in the raw wastewater, a calculation circuit, and a metal salt solution injection pump ('I2 are interlocked,
TOC of raw wastewater! By configuring a circuit to control the amount of metal salt-containing salt solution injected at a time,
Efficient processing can be performed automatically.

In addition, metal salt removal, -Ci,! 7. ．． A, 7. ,.

In addition to the respective rum and barium salts, other metal salts that produce insoluble or refractory salts can be used.

Further, the flow of the processing method is not limited to that shown in FIG. 4, and can be modified as appropriate.

As described above, according to the present invention, a metal ion-containing salt that forms an insoluble carbonate is injected during the hydrogen peroxide addition ozonation treatment, which causes a decrease in the efficiency of the hydrogen peroxide addition ozonation treatment. This has the effect of fixing dissolved carbonate radicals (bicarbonate ions, carbonate ions) as insoluble carbonates, and maintaining high treatment efficiency until the final treatment.

[Brief explanation of drawings]

Figure 1 is a system diagram showing the conventional ozone treatment method with hydrogen peroxide addition, Figure 2 is a curve diagram showing the effect of 7JO ozone treatment with hydrogen peroxide, and Figure 3 is the efficiency and coexistence of ozone treatment with hydrogen peroxide addition. FIG. 4 is a diagram showing the relationship between the concentration of bicarbonate ions and the concentration of bicarbonate ions, and FIG. 4 is a system diagram showing a treatment method according to an embodiment of the present invention. In each figure, the same reference numerals indicate the same or corresponding parts, (1)
is an ozone generator, (2) is an ozone reaction tank, (3) is a diffuser, (4) is an acid or alkali agent storage tank, (5)
is peroxide water X storage tank, (6) is raw water tank, C71, C81
, f9+', Q:15i;t pump, α[ is the exhaust ozone decomposer, (II+ is the metal salt solution storage tank. Agent: Shin Kuzuno - (1 other person)

Claims (1)

[Claims] (11) In a wastewater treatment method in which organic substances are oxidized using ozone and hydrogen peroxide, a metal ion-containing salt that forms insoluble or poorly soluble salts with carbonate radicals is added to raw wastewater. (2) A method for treating organic matter-containing wastewater according to claim 1, characterized in that the metal ion-containing salt is an alkaline earth metal ion-containing salt. ( 3) The organic substance according to claim 1 or 2, wherein the amount of the metal ion-containing salt added is set to be equal to or more than the sum of inorganic carbon and organic carbon contained in the wastewater. A method for treating wastewater containing metal ions. (4) A means for measuring the total carbon content in raw wastewater, a calculation circuit, and a metal ion-containing salt injection pump are linked. Injection of metal ion-containing salt in response to TOCll of raw wastewater Claim 1 characterized in that the amount is controlled.
A method for treating organic matter-containing wastewater according to any one of paragraphs 1 to 3.