JP3516327B2 - Method and apparatus for treating organic wastewater containing dioxins - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the treatment of organic wastewater, especially leachate and industrial wastewater.
That die by treating organic wastewater containing dioxin
The present invention relates to a treatment method and apparatus for reducing oxins .

[0002]

2. Description of the Related Art Conventionally, as a main treatment method for organic wastewater such as waste leachate, a treatment method mainly for removing organic substances has been used. The main treatment methods are BOD, biological treatment for removing nitrogen, chromaticity, COD and SS.
There are coagulation sedimentation treatments for the purpose of removing such substances, and sand filtration treatments for the purpose of removing suspended matters such as SS. Further, activated carbon treatment may be used as the advanced treatment method. But,
In any of the above treatment methods, there is little effect of decomposing and removing a trace amount of dissolved organic chlorine compounds in wastewater, especially dioxins, and organic chlorine compounds such as dioxins often remain in discharged water.

Further, dioxins and the like are almost insoluble in water, and even if the dioxins and the like in the treated water are reduced in each treatment step, most of the dioxins and the like removed from the water are generated in the treatment step. since entering and contained therein in a high dioxins-containing rate in the cake after dehydration treatment of the sludge, it is believed that there is not much degradation effect of removing dioxin and the like of the whole in the system. The decomposition processing techniques such as recent dioxin, generally organic pollutants and suspended dioxin dissolved in the treated water to remove substances, decomposition by the oxidation reaction according to dechlorination or ozone injection by ultraviolet irradiation Known to be removed.

[0004]

However, the amount of dioxins and the like that can be dissolved in water is extremely small, and there is almost no dioxins or the like in the treated water obtained by the conventional water treatment process.
Further, even if the treated water is decomposed and removed, the amount that can be decomposed and removed is only one-tenth or less of the total inflow amount. Therefore , most of the inflowing dioxins and the like are accumulated in the sludge generated in the treatment process, and the decomposition and removal of the sludge is a major issue. The present invention is intended to solve the above problems, and an object thereof is to provide a method for removing and decomposing dioxin and the like in a treatment system at a high removal rate. Further, the present invention, for the water to be treated, after the dissolved and non-dissolved dioxins and the like is decomposed and removed with high efficiency in advance,
A treatment method and apparatus capable of removing other organic pollutants and suspended substances from a conventional water treatment process and reducing the concentration of dioxin and the like in sludge generated from the water treatment process , separately. The purpose is to do.

[0005]

The present invention has solved the above problems by the following means. (1) In the method of treating organic wastewater containing dioxins, the water to be treated is treated with ozone and hydrogen peroxide.
Treated by the previous water treatment process using either one of the ultraviolet rays or a combination of the two , and further generate the treated water.
After the combined treatment of the material treatment and the coagulation treatment, the treated water
Either sand filtration treatment, activated carbon treatment, or
A method for treating organic wastewater containing dioxins, characterized in that the treatment is carried out by a latter-stage water treatment step performed by combining the two . (2) For sludge generated from the latter-stage water treatment step,
The method for treating organic wastewater containing dioxins according to the above (1), wherein waste ozone from the water treatment step in the first stage is introduced and the supernatant water is returned to the inflow section of the water treatment step in the second stage. (3) In a treatment apparatus for organic wastewater containing dioxins , peroxidized water is supplied to ozone supply means for treated water.
Element supply means or ultraviolet lamp
Water is treated by the previous stage water treatment device used in combination at the same time , and the treated water is further treated by the biological treatment device and the coagulation treatment device.
, And then treat the treated water with sand filter treatment equipment.
An apparatus for treating organic wastewater containing dioxins, characterized in that it is treated by a water treatment apparatus at a subsequent stage in which any one of the above apparatus and the activated carbon treatment apparatus is combined.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Dioxins and the like refer to dioxins. According to the present invention, for incoming raw water,
Prior to ozone treatment, use either hydrogen peroxide or ultraviolet light.
By performing the first or second combined water treatment step, the generated hydroxyl radicals and the like can oxidize and decompose dissolved and non-dissolved dioxins in the water to be treated with high efficiency. Regarding the organic substances, SS, and heavy metals in the treated water from which dioxins and the like have been removed by oxidative decomposition,
If a subsequent water treatment process such as biological treatment is performed, it can be removed and separated to a high degree.

As described above, dioxin in the raw raw water
In advance, since oxidative decomposition is performed in the first-stage treatment step, there is little residual dioxin etc. in the sludge generated from the water treatment step that removes organic matter and SS, etc., and the purpose was to decompose and remove dioxin etc. in sludge. Sludge treatment process can be reduced. Further, by injecting the waste ozone from the decomposition process of dioxins and the like into the sludge, not only the waste ozone can be treated but also the sludge volume reduction and dioxins, etc.
A further reduction of the free rate is also possible. Therefore, sludge emissions and dioxins-containing rate to the processing system out are both reduced.

In the present invention, in the water treatment step in the preceding stage, ozone treatment is performed using either hydrogen peroxide or ultraviolet rays.
One, or is performed a process that combines two, Oh <br/> Zon and hydrogen peroxide, ozone and ultraviolet rays, or can be used in two combinations of hydrogen peroxide and ultraviolet light, these 3 A better effect can be obtained by combining the persons. In the case of this combined use, the ozone may be first reacted and then the hydrogen peroxide may be sequentially used, but they may be simultaneously used. The usage amount and irradiation amount of these can be determined in consideration of the processing conditions and the like.

[0009]

The present invention will be described in detail below with reference to the drawings showing an example of an embodiment of the present invention. FIG. 1 is a flow sheet showing an example of the processing method according to the present invention. As shown in FIG. 1, hydrogen peroxide is injected into the landfill leachate as the water to be treated 1 through the hydrogen peroxide injection pipe 3, and is introduced into the dioxin decomposition device 4, and ozone is injected through the ozone injection pipe 2. Due to the action of the ultraviolet rays emitted from the ultraviolet ray irradiation lamp 5, dioxin in the water to be treated is oxidatively decomposed by hydroxy radicals having a strong oxidizing power. The treated water 6 obtained by the dioxin decomposition treatment is the latter water treatment step,
That is, the organic substances, SS, and heavy metals in the treated water are removed through the biological treatment device 8, the coagulation sedimentation treatment device 9, the sand filtration treatment device 10, and the activated carbon treatment device 11. Treated water obtained from the activated carbon treatment device 11 is the discharged water 1
It can be discharged out of the system as 2. The backwash water 15 of the sand filtration device 10 is returned to the inflow part of the coagulation sedimentation treatment device 9 to separate and remove SS and the like.

On the other hand, the biological treatment sludge 13 generated by the biological treatment device 8 and the coagulation sedimentation sludge 14 generated by the coagulation sedimentation treatment device 9 are collected in a sludge storage tank 17, and the dioxin decomposition is carried out in the sludge storage tank 17. If waste ozone 7 discharged from the upper part of the apparatus 4 is introduced, the waste ozone is consumed for sludge decomposition and oxidative decomposition of dioxins organic chlorine compounds, and the supernatant water 16 is returned to the inflow section of the biological treatment apparatus 8. The organic substances eluted with sludge decomposition can be removed by subsequent treatment. Since the residual sludge in the sludge storage tank 17 contains little dioxin, it is discharged outside the system as discharged sludge 18.

In the above treatment flow, biological treatment, coagulation sedimentation treatment, sand filtration and activated carbon treatment, which are the subsequent water treatment steps after decomposition and removal of organic chlorine compounds such as dioxins, are examples of removal of organic matter and SS from treated water. The coagulation-sedimentation treatment may be provided first depending on the property of the water to be treated, and the combination includes biological treatment + filtration treatment + activated carbon treatment, biological treatment + coagulation-sedimentation filtration + activated carbon treatment, and the like. As the biological treatment, any of a contact oxidation method, a rotating disk method, a standard activated sludge method, etc. may be used, and as an agglomeration treatment and a filtration treatment, an agglomeration membrane filtration, an agglomeration sedimentation and a sand filtration may be used. Further, instead of the sludge storage tank, a sludge decomposition tank may be provided after the sludge storage tank, and waste ozone may be introduced into the sludge decomposition tank.

Table 1 shows the water quality in each treatment step shown in FIG. 1, and Table 2 shows the water quality before and after sludge decomposition by exhaust ozone. Table 3 shows the treatment conditions for decomposing organic chlorine compounds such as dioxins.

[0013]

[Table 1]

As shown in Table 1, the total dioxin is 15
00pg / l, Dioxin TEQ 25pg /
Addition rate of hydrogen peroxide to 1 liter of water to be treated
After the decomposition reaction was carried out under the treatment conditions of 0 mg / liter, an ozone injection rate of 100 mg / liter, an ultraviolet irradiation amount of 0.5 W · hr / liter of raw water, and a residence time of 20 minutes, the total dioxin and dioxin TEQ of the treated water were both About 10
It was reduced to less than a factor of 1 and became 150 pg / liter and 2.0 pg / liter, respectively. Almost 90% of the inflowing dioxin could be removed by the dioxin decomposition reaction. In Table 1, “TEQ” is 2, 3, 7, 8-
TCDD toxicity equivalent conversion concentration is shown. TCDD stands for chlorodibenzotetrachloroparadioxine tetrachloride.

As representative pollutants other than dioxin, treated water has a chromaticity of 600 degrees and COD of 200 mg.
/ Liter, BOD 150 mg / liter, SS 1
The treated water after dioxin decomposition treatment has a chromaticity of 300 degrees, COD 150 mg / liter, BOD 170 mg / liter, SS 80 mg / liter.
Since the amount of the organic pollutant remains to a large extent, the discharged water obtained by the biological treatment, coagulation and sedimentation treatment, sand filtration, and activated carbon treatment in the subsequent treatment step has a chromaticity of 10 degrees and COD.
10 mg / liter, BOD, and SS were 1 mg / liter or less. Also, with the high removal of organic matter and SS, the total dioxin and dioxin TEQ in the discharged water were below the detection limit.

[0016]

[Table 2]

As shown in Table 2, the total dioxin of the mixed sludge from the biological treatment and the coagulation sedimentation treatment is 0.79 ng /
The total dioxin content in the sludge from the treatment process where dioxin-decomposing treatment is not normally performed is about one-tenth or less compared with about several tens ng / g. Further, 20 mg / liter of exhaust ozone was introduced into the above sludge, and after a residence time of about 3 hours, the SS of the sludge decreased from 15000 mg / liter before introduction of exhaust ozone to 13000 mg / liter, about 13%. The volume has been reduced. Further, total dioxin and dioxin TEQ decreased to 12,000 pg / liter and 200 pg / liter before ozone introduction, respectively, and decreased to 3000 pg / liter and 50 pg / liter after ozone treatment, respectively. The total dioxin in SS also fell to 0.22 ng / g. The effect of decomposing dioxin in SS was also obtained. The organic matter concentration in the sludge filtrate became slightly higher after introducing the exhaust ozone. If these are returned to the biological treatment inflow section, sufficient treatment is possible. Dioxins in the filtrate also increased slightly after the exhaust ozone treatment, but the total amount was small and could be sufficiently removed in the water treatment process, and the quality of the discharged water was not affected at all.

[0018]

[Table 3]

[0019]

As shown in the examples, according to the present invention, first, ozone is added to organic waste water containing dioxins and the like.
If the first stage treatment using either one of hydrogen peroxide and ultraviolet rays or a combination of two is performed, the treatment of dissolved and non-dissolved dioxins in the water to be treated can be carried out at a high efficiency of about 90%. Can be oxidatively decomposed. The water to be treated that has undergone dioxin decomposition treatment is then combined with further biological treatment and coagulation treatment.
After combined treatment, the treated water is further subjected to sand filtration treatment,
If any one of the activated carbon treatments or a combination of the two treatments is performed at a later stage, the organic matter of the water to be treated and other contaminants such as SS or heavy metals can be highly removed and separated. Further, since it is possible dioxins traces of still remaining after dioxin equally solution process is also almost completely removed by the subsequent water treatment, high-quality effluent can be obtained.

As described above, dioxins, etc. in the raw raw water
From what has be removed by first oxidizing decompose,
Dioxin residue in the sludge generated from the subsequent water treatment process that removes organic matter and SS etc. is small, and the dioxin content per solid unit is less than that of the treatment process that did not undergo dioxin decomposition treatment first. It is about 1/10 or less. Even if it is discharged as it is, the load on the environment can be greatly reduced. Further, by introducing the exhaust ozone from the dioxin decomposition treatment step into the sludge, not only the exhaust ozone can be treated, but also the volume of the sludge and the dioxin content can be further reduced. Therefore, the amount of sludge discharged to the outside of the treatment system and the total amount of dioxins both decrease.

[Brief description of drawings]

FIG. 1 shows a flow sheet of an example of a method for treating organic wastewater according to the present invention.

[Explanation of symbols] 1 treated water 2 Ozone injection tube 3 Hydrogen peroxide injection tube 4 Dioxin decomposition device 5 UV irradiation lamp 6 Dioxin decomposition treated water 7 Waste ozone pipe 8 biological treatment equipment 9 Aggregation and sedimentation treatment equipment 10 sand filter 11 Activated carbon treatment equipment 12 Discharged water 13 Biological sludge 14 Coagulation sedimentation sludge 15 Backwash drainage 16 Sludge treatment clear water 17 Sludge storage tank 18 discharged sludge

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C02F 9/00 C02F 9/00 502R 503 503C 504 504A 1/32 1/32 1/52 1/52 Z 1/58 ZAB 1 / 58 ZABA 1/72 1/72 Z 1/78 1/78 3/12 3/12 SV 11/06 11/06 A (72) Inventor Souta Nakagawa 4-2-1 Honfujisawa, Fujisawa, Kanagawa (56) Reference JP-A-5-228480 (JP, A) JP-A-6-63571 (JP, A) JP-A-3-229615 (JP, A) JP-A-59-112899 ( JP, A) JP 7-108285 (JP, A) JP 10-286597 (JP, A) JP 10-296299 (JP, A) JP 10-337579 (JP, A) JP JP-A-6-114384 (JP, A) JP-A-5-185093 (JP, A) JP-A-4-370097 (JP, A) 6-154743 (JP, A) JP-A-3-249990 (JP, A) JP-A-4-7082 (JP, A) JP-A-7-96297 (JP, A) JP-A-4-256433 (JP, A) A) JP-A-2-184393 (JP, A) JP-A-8-332479 (JP, A) JP-A-10-128315 (JP, A) JP-A-11-33570 (JP, A) JP-A-11 -33569 (JP, A) JP 11-33581 (JP, A) Industrial pollution, Japan, Japan Industrial Pollution Control Association, September 10, 1993, Vol. 29, No. 9, pp. 83-92. (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 1/00-11/20

Claims (3)

(57) [Claims] 1. A method for treating organic wastewater containing dioxins, comprising: treating water to be treated with ozone;
Either one of hydrogen fluoride and ultraviolet rays, or treated by the preceding water treatment step using a combination of two, and after treating the treated water by further combining biological treatment and coagulation treatment,
The treated water is further subjected to sand filtration treatment or activated carbon treatment.
A method for treating organic wastewater containing dioxins, which comprises performing one or a combination of the two in a subsequent water treatment step. 2. The sludge generated from the latter-stage water treatment process is introduced with the exhaust ozone from the former-stage water treatment process, and the supernatant water is returned to the inflow part of the latter-stage water treatment process. The method for treating organic wastewater containing dioxins according to claim 1. 3. An apparatus for treating organic wastewater containing dioxins, wherein ozone is supplied to the water to be treated ,
Either hydrogen peroxide supply means or UV lamp
One or two water treatment devices used in combination at the same time , and the treated water is further coagulated with the biological treatment device.
After treating with a treatment device, the treated water is treated with sand filter.
One or two of over-treatment device and activated carbon treatment device
A treatment device for organic wastewater containing dioxins, which is treated by a water treatment device at a latter stage in which the above are combined.