JPH08309392A - Waste water treatment process - Google Patents

Abstract

PURPOSE: To provide a treatment process for heavy metal containing waste water which can realize the simplification of treatment flow and space saving. CONSTITUTION: Water to be treated 16 is introduced into a treatment tank 14 in which an immersion type film module 27 is installed, and a liquid chelate is added therein and a heavy metal in the water to be treated 16 is reacted with the liquid chelate. The solid-liquid separation of water to be treated 16 in the tank containing a formed chelate compound is carried out by a film module 27, and film permeating water 18 permeated through a separating film of the film module 27 is taken outside the tank, while suspended substances like the chelate compound and others remain in the tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method for treating heavy metal-containing wastewater such as industrial wastewater, incinerator wastewater and landfill leachate.

[0002]

2. Description of the Related Art Wastewater containing heavy metals such as industrial wastewater, incinerator wastewater, landfill leachate, etc. is treated as shown in the flow chart of FIG.

That is, the waste water 1 is introduced into the rapid mixing tank 2, and the chelating agent 3 is added and rapidly stirred to obtain the waste water 1
The heavy metal contained therein is adsorbed on the chelating agent 3. Furthermore, while adding the coagulant 4 such as a sulfuric acid band, polyaluminum chloride (PAC), ferric chloride, or polyiron to the wastewater 1 in the tank, rapid stirring is performed to remove the chelating agent 3 having heavy metals adsorbed thereon. Aggregate to form fine flocs.

Then, the waste water 5 containing the fine flocs in the rapid mixing tank 2 is introduced into the slow mixing tank 6, and the polymer flocculant 7 is added.
Is added and both are slowly stirred to grow fine flocs in the wastewater 5.

Then, the wastewater 8 containing flocs in the slow mixing tank 6 is allowed to flow into the coagulation sedimentation tank 9, and the flocs are allowed to settle by gravity, and then the supernatant liquid in the sedimentation tank 9 is sent to the treated water tank 11. Once stored, it is discharged as treated water 12, and sludge 13 made of sedimented flocs is properly taken out.

[0006]

However, in the above-mentioned conventional treatment method, a rapid mixing tank for adding and mixing chemicals such as chelating agents and aggregating agents, and a slow mixing tank for growing flocs are used. In addition to the necessity, a flocculating sedimentation basin for gravity-precipitating flocs is required, and a large space for that is required. for that reason,
There is a problem that not only the processing flow becomes complicated, but also the installation space becomes large.

The present invention solves the above problems, and an object of the present invention is to provide a wastewater treatment method capable of simplifying the treatment flow and saving space.

[0008]

In order to solve the above problems, a wastewater treatment method of the present invention is a wastewater treatment method for treating heavy metal-containing wastewater, wherein a treatment tank in which a submerged membrane module is installed is to be treated. Water is introduced, and a chelating agent is added to react heavy metals in the water to be treated with the chelating agent to form a chelate compound, and the water to be treated in the tank containing this chelate compound is solid-liquid separated by the membrane module. The membrane permeated water that has permeated the separation membrane of the membrane module is taken out, and the suspended substance such as the chelate compound is left in the tank.

Further, the wastewater treatment method of the present invention is a wastewater treatment method for treating heavy metal-containing wastewater, in which the water to be treated is introduced into a treatment tank in which a submerged membrane module is installed, and a chelate resin is added to the treated water. The heavy metal in the treated water is adsorbed to the chelate resin to form a chelate compound, and the water to be treated in the tank containing this chelate compound is subjected to solid-liquid separation by the membrane module, and the membrane-permeated water that has permeated the separation membrane of the membrane module is taken out. The suspended substance such as the chelate compound is allowed to remain in the tank.

Furthermore, in the wastewater treatment method of the present invention, a coagulant is added to the water to be treated in the treatment tank containing the chelate compound to cause the chelate compound to aggregate, and the water to be treated containing the aggregated flocs produced thereby is formed into a film. Solid-liquid separation is performed by the module, and the membrane-permeated water that has permeated the separation membrane of the membrane module is taken out so that the suspended substance such as the floc flocs remains in the tank.

Further, in the wastewater treatment method of the present invention, the membrane permeated water is introduced into a chelate resin tower filled with a chelate resin,
The heavy metal remaining in the membrane-permeated water is removed.

[0012]

Function The immersion type membrane module is an array of separation membranes having fine pores formed therein, and is capable of separating even minute suspended substances. According to the first configuration described above,
Inside the treatment tank, the heavy metal reacts with the chelating agent to produce a chelate compound, which is separated by the separation membrane of the membrane module and remains inside the treatment tank. That is, heavy metals are separated and recovered by a simple configuration of a treatment tank having a membrane module and a chelating agent.

Also in the above-mentioned second structure, as in the first structure, the heavy metal is separated and recovered by the simple structure of the treatment tank in which the membrane module is installed and the chelate resin. According to the above-described third configuration, the chelate compound is formed into floc so that the chelate compound reliably remains inside the processing tank.

According to the above-mentioned fourth structure, the membrane-permeated water from which the heavy metals have been separated in the treatment tank is guided to the chelate resin tower, and the remaining heavy metals are further separated, so that the heavy metals are reliably removed. Treated water is obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 14 is a submerged membrane separation device 15 installed therein, and water to be treated 16 containing a heavy metal 16
Is a treatment tank into which is introduced, 17 is a permeated water tank into which the permeated water 18 that has been treated inside the treatment tank 14 and has permeated the separation membrane of the membrane separation device 15 is introduced, and 19 is filled with a chelate resin 20. It is a chelated resin tower.

The treated water supply pipe 2 is provided above the treatment tank 14.
1, the first chemical injection pipe 22 and the second chemical injection pipe 23 are opened, the sludge drawing pipe 24 is provided at the bottom, and the membrane separation device 15
An aeration device 26 connected to a blower 25 outside the tank is provided below the.

The membrane separation device 15 is formed by laminating a plurality of membrane modules 27 composed of a plurality of tubular ceramic separation membranes, and the inside of the ceramic separation membranes, that is, the permeated water flow passage communicates with a permeated water pipe 28. The permeate pipe 28 is provided with a control valve 29 and a suction pump 30,
The membrane permeated water 18 that has permeated the membrane surface of the ceramic separation membrane is sent to the permeated water tank 17.

The permeated water tank 17 is provided with a backwash water supply pipe 31 communicating with the permeated water pipe 28, and the tank 17 is operated by operating the control valve 32 and the backwash pump 33.
The membrane permeated water 18 stored therein is pressure-fed to the inside of the ceramic separation membrane through the backwash water supply pipe 31 so that the ceramic separation membrane can be backwashed.

The operation of the above structure will be described below.
The treated water 16 is introduced into the treatment tank 14 through the treated water supply pipe 21, the liquid chelate as the chelating agent is added to the treated water 16 through the first chemical injection pipe 22, and the aerator is supplied from the blower 25. Aeration air is supplied through 26 to stir and mix the water 16 to be treated and the liquid chelate in the tank. After an appropriate time, the aggregating agent is added to the water 16 to be treated in the treatment tank 14 through the second chemical injection pipe 23 while stirring and mixing. As a result, a chelate compound is generated by the reaction between the heavy metal in the water 16 to be treated and the liquid chelate,
This chelate compound is aggregated with a flocculant to form floc.

After the flocculation flocs are sufficiently formed, the control valve 29 is opened and the suction pump 30 is driven to suck the inside of the ceramic separation membrane of the membrane module 27, that is, the permeate flow path through the permeate pipe 28. By applying pressure, the permeated water 18 that has permeated the separation membrane and flowed into the permeated water flow path is sent to the permeated water tank 17 through the permeated water pipe 28, and the flocs that do not permeate the separation membrane enter the treatment tank 14. Let it remain.

The membrane permeated water 18 in the permeated water tank 17 is guided to the chelate resin tower 19 and passed through the gap between the chelate resins 20 so that the heavy metal remaining in the membrane permeated water 18 is adsorbed by the chelate resin 20. The treated water 34 from which the heavy metals have been removed is taken out.

Aggregated flocs containing heavy metals remaining in the treatment tank 14 are appropriately recovered through the sludge drawing pipe 24.
In the above examples, the liquid chelate was added to react with the heavy metal, and the produced chelate compound was aggregated by the aggregating agent to ensure the separation of the heavy metal, but the chelate resin was added instead of the liquid chelate. The heavy metal may be adsorbed thereto, or the chelate compound can be separated by the membrane module 26 even if the aggregating treatment is omitted.

[0023]

As described above, according to the present invention, the heavy metal in the heavy metal-containing wastewater can be separated and recovered with a simple structure in which the treatment tank having the membrane module and the chelating agent are used. Therefore, as compared with the conventional method, the processing flow can be simplified, and the processing tank in which the membrane module is installed can replace the rapid mixing tank, the slow mixing tank, and the coagulation sedimentation tank, so that space can be saved.

Similarly, the heavy metal contained in the heavy metal-containing wastewater can be separated and recovered by a simple structure in which a treatment tank having a membrane module and a chelate resin are used. Further, since the chelate compound generated by adding the chelating agent or the chelating resin is further aggregated, the solid-liquid separation is performed by the membrane module, so that the heavy metal in the heavy metal-containing wastewater can be separated and recovered more reliably. Compared with the conventional method, the polymer coagulant is not required, so the processing flow can be simplified.

Further, since the heavy metal remaining in the membrane-permeated water from which the heavy metal has been removed in the treatment tank is further removed in the chelate resin tower, the treated water from which the heavy metal has been reliably removed can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a wastewater treatment device in which a wastewater treatment method according to an embodiment of the present invention is performed.

FIG. 2 is a flowchart showing a conventional wastewater treatment flow.

[Explanation of symbols]

 14 Treatment tank 16 Treated water 18 Membrane permeated water 19 Chelating resin tower 20 Chelating resin 22 First chemical injection pipe (liquid chelate) 23 Second chemical injection pipe (coagulant) 27 Immersion type membrane module

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C02F 1/44 ZAB C02F 1/44 ZABE 1/62 ZAB 1/62 ZABZ (72) Inventor Ken Yoshizaki 2-1-1, Nishijima, Nishiyodogawa-ku, Osaka City, Osaka Prefecture Kubota Shin-Yodogawa Factory

Claims (4)

[Claims] 1. A wastewater treatment method for treating heavy metal-containing wastewater, which comprises introducing the water to be treated into a treatment tank having a submerged membrane module and adding a chelating agent to chelate heavy metals in the water to be treated. React with the agent to form a chelate compound,
The water to be treated in the tank containing the chelate compound is subjected to solid-liquid separation by the membrane module, the permeated water that has permeated the separation membrane of the membrane module is taken out, and the suspended substance such as the chelate compound is left in the tank. A wastewater treatment method characterized by the above. 2. A wastewater treatment method for treating heavy metal-containing wastewater, wherein the water to be treated is introduced into a treatment tank having an immersion type membrane module, and a chelate resin is added to convert heavy metals in the water to be treated into a chelate resin. Adsorbed and made into a chelate compound,
The water to be treated in the tank containing the chelate compound is subjected to solid-liquid separation by the membrane module, the permeated water that has permeated the separation membrane of the membrane module is taken out, and the suspended substance such as the chelate compound is left in the tank. A wastewater treatment method characterized by the above. 3. An aggregating agent is added to the water to be treated in the treatment tank containing the chelate compound to aggregate the chelate compound, and the water to be treated containing agglomerated flocs is solid-liquid separated by a membrane module. 3. The method for treating wastewater according to claim 1, wherein the permeated water that has permeated the separation membrane of the membrane module is taken out, and the suspended substances such as the flocs of flocs are left in the tank. 4. The membrane permeated water is introduced into a chelate resin column filled with a chelate resin to remove heavy metals remaining in the membrane permeated water, according to any one of claims 1 to 3. Wastewater treatment method.