JP2000210663A - Method of removing dioxins in waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method of removing dioxins in waste water which is capable of removing the dioxins in the waste water upto a concn. as low as possible. SOLUTION: The waste water from the dumping site exudation water treating device at a rubbish final disposal site and various kinds of industries is stored in a waste water tank 1 at an existing waste water treating equipment, then the waste water is sent to a chemical mixing tank 2 to add a flocculating agent, etc., then the waste water is sent to a flocculating and settling tank 3 to remove precipitated matter. Then the waste water is sent to a neutralizing tank 4 and made to pass through a sand filter column 5 then stored in a discharge tank 6, and discharged to out of system as required or reused. At the time of executing the removing method of the dioxins in the waste water, the waste water passing through the send filter column 5 is treated at a membrane separation device 7, and water permeating the membrane is made to pass through an activated carbon adsorption column 8 to be subjected to adsorption treatment, and the treated water finally is returned to the original line of the existing waste water treating equipment before the discharge tank 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing dioxins in waste water. Dioxins are mainly generated in refuse incineration facilities and are contained in exhaust gas, and are further transferred to ash and sewage. The present invention relates to a method for removing dioxins from wastewater discharged from a wet smoke cleaning facility of a refuse incineration facility, and effluent discharged from a landfill leachate treatment facility at a landfill waste disposal facility and existing wastewater treatment facilities in various industries.

[0002]

2. Description of the Related Art At present, there are no legal restrictions on dioxins in wastewater treatment, but research and development are being advanced on treatment technologies. According to the “Guidelines for Prevention of Dioxin Generation Related to Garbage Disposal”, removal of SS is effective in removing dioxins because dioxins have low solubility in water. It has been confirmed that the amount of wastewater has been reduced by the method and the biological filtration method, and it merely states that it is necessary to maintain and control the wastewater so that the SS concentration is 10 mg / liter or less for the time being.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for removing dioxins in wastewater, which can remove dioxins in wastewater to the lowest possible concentration.

[0004]

SUMMARY OF THE INVENTION The present invention focuses on the fact that the properties of dioxins are divided into soluble and particulate forms, and from the step of completely removing soluble dioxins and particulate dioxins, respectively. Become.

[0005] That is, the method for removing dioxins in wastewater according to the present invention is characterized in that wastewater containing dioxins is first subjected to membrane separation treatment and then to activated carbon adsorption treatment.

[0006]

As described above, dioxins in waste water can be roughly classified into soluble dioxins and particulate dioxins. Although the solubility of dioxins in water is extremely low, the solubility in organic solvents and the like is high, and so there are soluble dioxins. On the other hand, it has been known that powdered dioxins exist in a state of being adsorbed by an organic substance or SS (floating substance). Soluble dioxins are
Almost 100% can be removed by adsorption removal with activated carbon, but there is a problem that the activated carbon packed bed is blocked by SS, and as a countermeasure, it is necessary to backwash the activated carbon packed bed.

In the method for removing dioxins in wastewater according to the present invention, SS is reduced to almost 1 before the activated carbon adsorption treatment.
Since the membrane separation treatment capable of removing 00% is performed, the particulate dioxins adsorbed on the SS by the membrane separation treatment can be removed. Next, soluble dioxins can be removed by activated carbon adsorption treatment. Thus, almost 100% of dioxins in the wastewater can be removed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method for removing dioxins in waste water according to the present invention will be specifically described with reference to two examples.

Embodiment 1 In this embodiment, as shown in FIG. 1, the method of the present invention is applied to the treatment of wastewater discharged from an existing wastewater treatment facility.

[0010] Wastewater from landfill leachate treatment facilities and various industries at the final landfill site is stored in the drainage tank (1) in the existing wastewater treatment facility, and then sent to the chemical mixing tank (2) to be discharged there. After the coagulant is added in the coagulation settling tank
Sent to (3) where the sediment is removed. The wastewater is then sent to the neutralization tank (4), passed through the sand filtration tower (5), stored in the discharge tank (6), and discharged to the outside of the system as necessary, or reused. Shared.

In order to carry out the method for removing dioxins in waste water according to the present invention, the waste water after passing through a sand filtration tower (5) is first treated in a membrane separator (7), and the permeated water is then removed. The treated water is passed through the activated carbon adsorption tower (8) for adsorption treatment, and this treated water is returned to the original line of the existing wastewater treatment facility upstream of the discharge tank (6).

Embodiment 2 In this embodiment, as shown in FIG. 2, the method of the present invention is applied to the treatment of wastewater discharged from a wastewater treatment device in a wet smoke cleaning facility of a refuse incineration facility.

The smoke discharged from the incinerator (11) of the refuse incineration facility is passed through a dust collector (12) such as an electric dust collector, a bag filter, etc., and then a smoke tower (13) of a wet smoke cleaning facility. Sent to the bottom. In the upper part of the smoke washing tower (13), washing water circulating through a water storage tank (15), a circulating pump (16) and a cooler (17) is sprinkled with a nozzle (14), and the smoke washing tower (13) is sprayed. In the lower part, washing water circulating through a circulation pump (18) is sprinkled by a nozzle (14). The flue gas is wet-smoke-washed while ascending in the smoke-wash tower (13), and then the processing gas is released outside the system via the gas reheater (19) and the chimney (20).

The wastewater from the bottom of the smoke tower (13) is sent to a wastewater treatment facility (21). In order to treat this smoke-washing wastewater by the method for removing dioxins in wastewater according to the present invention, the wastewater is first treated by a membrane separation device (22), and the permeated water is then passed through an activated carbon adsorption tower (23) to be subjected to an adsorption treatment. This treated water is discharged outside the system.

In order to treat the washing water circulating in the upper part of the smoke washing tower (13) by the method for removing dioxins in waste water according to the present invention, first, the washing water is removed from the water storage tank (15) by a membrane separation device (15). Two
4), membrane separation treatment is carried out, and the permeated water is then passed through an activated carbon adsorption tower (25) for adsorption treatment, and this treated water is returned to the water storage tank (15).

[0016]

According to the present invention, before the activated carbon adsorption treatment, a membrane separation treatment capable of removing almost 100% of SS is performed, so that particulate dioxins adsorbed on SS by the membrane separation treatment are removed. Then, soluble dioxins can be removed by activated carbon adsorption treatment, and dioxins in wastewater can be removed by almost 100%.

When the waste water is waste water discharged from a wet smoke washing facility, the method of the present invention is also applicable to a process for removing dioxins in exhaust gas.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an example in which the method of the present invention is applied to the treatment of wastewater discharged from an existing wastewater treatment facility.

FIG. 2 is an example flow sheet in which the method of the present invention is applied to the treatment of wastewater discharged from a wastewater treatment device in a wet smoke cleaning facility of a refuse incineration facility.

[Explanation of symbols]

 5: Sand filtration tower 6: Discharge tank 7, 22, 24: Membrane separation device 8, 23, 25: Activated carbon adsorption tower 13: Smoke washing tower 15: Water storage tank

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA02 KA02 KA03 KA71 KB12 KB13 KB15 KD08 KD19 KE12P KE13P KE15Q PA01 PB08 PB70 PC80 4D024 AA04 AB11 BA02 CA01 DB03 DB05 DB20 DB21

Claims (3)

[Claims] 1. A method for removing dioxins in waste water, comprising first subjecting waste water containing dioxins to membrane separation treatment and then subjecting the waste water to activated carbon adsorption treatment. 2. The method according to claim 1, wherein the wastewater is wastewater discharged from a wet smoke cleaning facility of a refuse incineration plant. 3. The method according to claim 1, wherein the wastewater is wastewater discharged from an existing wastewater treatment facility.