JP2003094062A - Method and equipment for treating wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating a car washing waste water, or the like, at a low cost; and a wastewater treatment equipment which is small-typed, for which an installation area is small, which is simple in structure, for which an introduction cost is low, and with which a small-scale wastewater treatment is easily performed. SOLUTION: The wastewater treatment method comprises a process in which a contaminated component which can be coagulated and separated with an aluminum ion and a wastewater containing a solvent component which is not coagulated with the aluminum ion are electrolyzed in an electrolyzation treatment bath containing an aluminum piece to coagulate the contaminated component, a process which separates the coagulated substances, and a process which performs an activated sludge treatment on a treated wastewater after the coagulated substances are separated in an activated sludge treatment bath; and the wastewater treatment equipment is used to treat the contaminated component which can be coagulated and separated with the aluminum ion and the wastewater containing the solvent component which is not coagulated with the aluminum ion, wherein the water treatment equipment is provided with the electrolyzation treatment bath containing the aluminum piece, a slid-liquid separation device which separates the coagulated substances coagulated by allowing the substances to contact with the aluminum ion in the electrolyzation bath and the activated sludge treatment bath which treats the treated wastewater after the coagulated substances are separated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating waste water, and more particularly to a method for treating waste water containing an emulsion containing mainly oils such as surfactants and waxes, particularly car wash at a gas station. The present invention relates to a wastewater treatment method and apparatus suitable for treating a relatively small amount of wastewater, including wastewater.

[0002]

2. Description of the Related Art Currently, relatively small-scale wastewater discharged from gas stations and small-scale manufacturers can be treated in a dedicated septic tank. However, in order to perform wastewater treatment using a biological method such as the activated sludge method, a large treatment tank is required, which requires a large amount of cost and a large space. For this reason, it is virtually impossible to install treatment equipment at most small-scale gas stations, and as a result, wastewater is left untreated, which is one of the causes of pollution of rivers and lakes. It is a big social problem. Several wastewater treatment methods have been proposed for this problem. Most of them use membrane separation, coagulation separation using a polymer coagulant, and adsorption separation using carbon black, and neither method is easy to maintain and the running cost is high. The reason is that it is not widely used for the reason.

Japanese Unexamined Patent Publication (Kokai) No. 12-000585 proposes a treatment system in which an oil / water separation tank and an activated sludge treatment tank are combined. However, since a surfactant dissolved in water cannot be separated, the activated sludge treatment tank The processing load on the
There is a problem that it is difficult to downsize the device. In addition, JP 2000
-176482, JP 2000-5761, JP 11-12892
Japanese Patent Application Laid-Open No. 7-290857 and Japanese Patent Application Laid-Open No. 11-290857 describe a system combining electrolysis and activated sludge method. In these systems, electrolysis treatment is adopted as a pretreatment process to remove a few ppm of phosphorus, which is difficult to remove in the subsequent activated sludge treatment process, but the main treatment is by the activated sludge method. Therefore, there is a problem that the load of treatment in the activated sludge treatment tank becomes large and it is difficult to downsize the device. In the above conventional method, wastewater containing a large amount of a surfactant or an oily wax emulsion such as car wash wastewater has a large load in the activated sludge treatment. This requires an activated sludge treatment tank, which is often difficult to implement in terms of cost.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for treating wastewater containing a large amount of a surfactant or an oily wax emulsion such as car wash wastewater at low cost. . Another object of the present invention is to
It is an object of the present invention to provide a wastewater treatment device which is small in size, has a small installation area, is simple in equipment, inexpensive to introduce, and easy to perform small-scale wastewater treatment. Still another object of the present invention is to provide a wastewater treatment method and apparatus capable of collecting and reusing treated water, reducing running costs, and solving environmental problems at low cost. .

[0005]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to solve the above problems, the following conclusions were reached. Most of the wastewater of gas stations and the like is wastewater discharged when using a car wash machine, and most of the pollutant components of these wastewater are anionic surfactants, waxes, emulsion oils such as silicones, Furthermore, it contains a small amount of a water-soluble solvent such as glycol or alcohol. Since anionic surfactants, waxes, silicones, etc. easily react with polyvalent cations such as aluminum ions and iron ions and agglomerate, these polyvalent ions are generated in situ in wastewater by electrolysis. By eluting,
Most of the above oil can be removed by coagulation.
In addition, water-soluble solvents such as glycol and alcohol that are difficult to remove by this electrolysis treatment are removed by activated sludge treatment, but since the content of these solvents is relatively small, use a large activated sludge treatment tank. do not have to. In short, most of the pollutable components that can be coagulated can be removed by electrolysis, and then a smaller amount of solvent components that were not removed by electrolysis coagulation can be removed with high efficiency by activated sludge treatment. It has been found that the object of the present invention can be easily achieved at low cost by using a small-sized device, requiring a small installation area. The present invention has been completed based on the above findings.

According to the present invention, waste water containing a large amount of pollutant components that can be aggregated and separated with aluminum ions or iron ions and a small amount of solvent components that do not aggregate with aluminum ions or iron ions is used as an electrical component containing aluminum and / or iron pieces. The first step of aggregating a large amount of pollutant components that can be aggregated and separated with aluminum ions or iron ions by electrolysis in a decomposition treatment tank, the second step of separating aggregates, and the treated wastewater from which the aggregates are separated are activated. The third process of activated sludge treatment in a sludge treatment tank
The present invention provides a method for treating wastewater, which comprises steps. The present invention also provides a wastewater treatment apparatus containing a large amount of contaminant components that can be aggregated and separated with aluminum ions or iron ions and a small amount of solvent components that do not aggregate with aluminum ions or iron ions. An electrolytic treatment tank containing the solid-liquid separation device for separating aggregates aggregated by contacting with aluminum ions and / or iron ions in the electrolytic treatment tank, and treating the treated wastewater from which the aggregates are separated The present invention provides a wastewater treatment apparatus including an activated sludge treatment tank.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. In the wastewater treated in the present invention, most of the pollutant components, for example, 50% by mass or more, preferably 70% by mass or more, are pollutant components that can be aggregated and separated with aluminum ions or iron ions, and typically, Contains a surfactant and / or wax component and contains a minor portion of the contaminant component, eg 5
Less than 0% by weight, preferably less than 30% by weight, is the solvent component, which is water-soluble. Suitable wastewaters for treatment according to the present invention include carwash wastewater, especially carwash wastewater from gas stations and coin carwash areas, kitchen wastewater discharged from cafeterias and homes. In the present invention, preferably, in the first step, it is preferable to agglomerate at least 70% by mass of the pollutant components that can be coagulated and separated with aluminum ions or iron ions from the viewpoint of reducing the load on the activated sludge treatment in the third step. Further, from the viewpoint of avoiding an increase in the size of the apparatus, the ratio of the wastewater retention time of the first step and the wastewater retention time of the third step is preferably 1:20 or less, more preferably 1:15 or less, and further preferably 1 :. It is desired to be 10 or less, and most preferably 1: 5 or less. Therefore, in the apparatus of the present invention, the ratio of the wastewater capacity of the electrolysis treatment tank to the wastewater capacity of the activated sludge treatment tank is preferably 1:20 or less, more preferably 1:15 or less, further preferably 1:10 or less. , And most preferably 1: 5 or less.

As an electrolytic treatment tank, Japanese Patent Laid-Open No. 6-86
Devices such as those disclosed in Japanese Patent Publication No. 984 and Japanese Patent Laid-Open No. 9-108502 are preferable. These devices have a flow passage for passing waste water or a space for holding the waste water, and a box-shaped cage formed of an insulator is arranged inside the flow passage or inside the space. A cathode plate is arranged along one side of the cage along the water flow or along the side surface of the cage, and an anode plate is arranged in parallel with the cathode plate on the opposite side of the cage, and the anode plate is It is characterized in that a space between the cathode plates is filled with a metal waste material of aluminum or iron, and the metal ions of the waste material are eluted by energizing the cathode plate and the anode plate.

Hereinafter, an example of an apparatus for carrying out the method of the present invention will be described more specifically with reference to FIGS. 1 and 2. In the first step, waste water such as car wash waste water is added as needed.
After adjusting H to 6 to 9, it is continuously or batchwise supplied to the electrolysis treatment tank 10. As shown in FIG. 2, the electrolysis treatment tank 10 is filled with a metal waste material 11 such as aluminum or iron, and when electric current is passed through the electrode plates 12 and 13 installed in the treatment tank, electrolysis is performed. As a result, cations such as aluminum and iron are eluted from the waste metal material 11.
The eluted cations react with anionic surfactants, waxes, silicones, etc., which are components capable of coagulation in the waste water, and these components coagulate.

The waste liquid treated in the first step is then sent to the solid-liquid separation device 20 in the second step. In the solid-liquid separation device 20, the aggregate is separated by solid-liquid separation means such as filtration or centrifugation. FIG. 1 shows a solid-liquid separation device (filtration device) 20 provided with a filtration membrane as a solid-liquid separation means.

The treated wastewater, which has been subjected to solid-liquid separation in the second step and from which agglomerates have been removed, is then used in the activated sludge treatment device 30 of the third step.
Sent to. In the activated sludge treatment device 30, the first and second
The wastewater treated in the treatment process is treated with activated sludge. The activated sludge-treated wastewater is further sent to the solid-liquid separation device 40 to separate solid matters such as activated sludge, and the finally treated water is further treated when necessary (for example, sterilization treatment, etc.). ) Is applied and reused as washing water, or it is discharged as it is to the sewage.

A preferred example of the electrode decomposition treatment tank 10 will be described below, but the present invention is not limited thereto. The treatment tank 10 has a space for holding wastewater, and a box-shaped cage 14 formed of an insulator is disposed inside the flow path or inside the space, and one end of the cage 14 is disposed. The cathode plate 12 is arranged along the water stream or along the side surface of the cage, and the anode plate 13 is disposed in parallel with the cathode plate 12 at the center of the cage 14 or on the side opposite to the cathode plate 12. Between the plate 13 and the cathode plate 12, a scrap metal 1 of aluminum or iron
1 has a structure in which metal ions such as aluminum or iron ions are eluted from the waste metal 11 by energizing the cathode plate 12 and the anode plate 13 with electricity.

As the metal waste material 11, a waste material such as an aluminum empty can, an iron empty can, and an aluminum sash can be used. As a scrap metal, a scrap metal of an aluminum can is preferable because it is easily available and has a good aggregation effect. Since the waste metal 11 can be replenished with the anode simply by putting it in the cage 14, the maintenance of the electrode is extremely easy, and the special work for exchanging the electrode as in the past or the dedicated expensive It is not necessary to procure or frequently replace a large electrode, which is extremely advantageous in terms of cost. Further, since the metal waste material 11 having various shapes has a very large reaction surface, the processing capacity per volume is large, and the apparatus can be downsized.

In the electrolysis treatment tank 10, waste water having a pollutant concentration of about 100 to 5000 ppm including an anionic surfactant which is a main component of a cleaning agent for a car washing machine and a wax emulsion which is a main component of a wax agent is used. , React with cations eluted from the waste material (and part of the electrode) to cause aggregation. The aggregate is further separated by the solid-liquid separator 20.
In the present invention, in order to reduce the load of the activated sludge treatment in the third step as much as possible, at least 70% by mass, preferably 80% by mass or more of the pollutant components which can be coagulated and separated by aluminum ions or iron ions are used in the first and It is desirable to remove it in the second processing step. Removal rate is 7
If it is less than 0% by mass, the load on the activated sludge treatment tank 30 in the third step becomes large, and as a result, the processing tank 30 becomes large, and therefore the installation space becomes large and the cost becomes high, which is not preferable.

The solid-liquid separation device used in the present invention may be any device as long as it can effectively separate aggregate flocs. For example, it may be separated by filtration using a filtration membrane, or may be separated by using a centrifugal device. The activated sludge treatment tank 30 is used as a low temperature stabilizer in a small amount of oil such as a surfactant which is not removed by the electrolysis treatment and the subsequent solid-liquid separation treatment, and a wax agent and a detergent for car wash machines. It is for decomposing glycols and the like. The activated sludge used is preferably a sludge that easily decomposes those components, but an aerobic sludge used in public sewerage treatment plants is sufficient. The wastewater treated with activated sludge is subjected to solid-liquid separation treatment, and the recovered water can be reused as washing water. The treatment method of the present invention may be batchwise or continuous, but continuous treatment is preferable because it is easy to control.

Overview of the apparatus and treatment conditions used in the examples An electrolysis treatment tank 10 (dimensions: width 200 mm width 150 mm height 160 mm) was prepared as an electrolysis treatment device for waste water. In this electrolysis treatment tank 10, an aluminum cathode plate 12 and an anode plate 13 (dimensions: width 170 mm, width 2 mm, length 130 mm)
And a plastic cage 14 was placed inside the electrodes, and a dozen or more crushed 500 ml aluminum cans were placed inside the cage 14. The electrodes were set so that the cathode and anode were switched by a current rectifier every 10 minutes. The current-rectifier controlled the voltage-electricity at any time. The electric output was 25V-0.5A to 2A. As the solid-liquid separator 20, a Teflon (registered trademark) non-woven fabric (made by DuPont: dimensions 400 mm × 500 mm) is used as a basket (dimension: 300).
mm × 400 mm × 150 mm), which is stretched on the upper surface,
A filtration device equipped with a liquid receiver on the bottom was used. Next, as the activated sludge treatment tank 30, a stainless container having a capacity of about 40 L (diameter 350 mm, height 400 mm) equipped with a stirrer and an aerator was used. Also, this activated sludge treatment tank 30
As the activated sludge, 30 L of aerobic activated sludge used in the sewer treatment of the Itako Water Purification Center was placed in the activated sludge treatment tank 30 in advance.

Next, 100 ml of car wash wastewater from a gas station
It was continuously supplied to the electrolysis treatment tank 10 at a rate of / hr, and the treatment liquid was caused to overflow from the overflow pipe in the upper portion of the electrolysis treatment tank 10 and flowed out onto the filtration membrane of the filtration device 20. The retention time of wastewater was set to 40 minutes. The filtrate was made to flow from the tray of the filtration device 20 into the activated sludge treatment tank 30. The treatment liquid was continuously supplied to the bottom of the 1 L solid-liquid separation tank 40 at a rate of 100 ml / min so that the residence time of the liquid in the activated sludge treatment tank 30 was about 300 minutes. Every 30 minutes, the precipitated activated sludge was returned to the activated sludge treatment tank 30. The treatment liquid was made to overflow from the upper part of the solid-liquid separation tank 40 to make the final treatment liquid.
The COD of undiluted wastewater, electrolysis treatment wastewater, and final treatment wastewater was measured.

Example 1 Water: 80% by mass, linear alkylbenzene sulfonic acid N
a: 12% by mass, higher alcohol ethoxylate (Adecatol TN-40: made by ADEKA): 4% by mass, 3-methyl-3-methoxy-1-butanol: 4% by mass, to prepare a detergent for car wash machine, This was diluted 200 times with tap water to obtain waste water. The pH at this time was 7.5, and the pH was not adjusted again. COD of undiluted solution of wastewater at this time
Was 700 mg / L. 100m of the wastewater prepared above
At a rate of 1 / min, the solution was continuously flowed into the electrolysis treatment tank 10 of the sled, and after 20 hours, the liquid was sampled and the COD was measured.

Example 2 The same as Example 1 except that a commercially available Falcon wax (manufactured by Power-Up Japan) containing carnauba wax or paraffin wax as a wax agent for car wash was diluted 200 times with tap water to obtain waste water. The operation was performed. The COD of this wastewater stock solution was 1200 mg / L.

Example 3 Amino-modified silicone as a wax agent for car wash: 10
% By mass, nonionic surfactant (Finesurf TD-5
0: made by Aoki Yushi Co., Ltd.): 2 mass%, water: 88 mass% containing an emulsion was prepared with a homogenizer, tap water to 200
The same operation as in Example 1 was performed except that the waste water was diluted by a factor of 2. The COD of this wastewater stock solution was 80 mg / L.

Comparative Example 1 The same operation as in Example 1 was performed except that the liquid was not treated in the electrolysis treatment tank 10. Comparative Example 2 The same operation as in Example 2 was performed except that the liquid was not treated in the electrolysis treatment tank 10. Table 1 shows the COD measurement results of the examples and comparative examples.

[0021]

[Table 1] From Table 1, it can be seen that in the wastewater treated by the method of the present invention, COD
In contrast to the sharp decrease in the value, in Comparative Examples 1 and 2 in which the electrolysis treatment was not performed, the reduction in COD was extremely small, and in order to obtain the same water quality as that of the example, an extremely large activated sludge was used. It can be seen that a treatment tank is required.

[0022]

According to the present invention, wastewater containing a large amount of a surfactant or an oily wax emulsion, such as car wash wastewater, can be treated at low cost. INDUSTRIAL APPLICABILITY The treatment apparatus of the present invention is small, has a small installation area, is simple and inexpensive to introduce, and is suitable for performing small-scale wastewater treatment. According to the present invention, treated water can be collected and reused, running costs can be reduced, and environmental problems can be solved at low cost.

[Brief description of drawings]

FIG. 1 is a drawing showing an outline of a wastewater treatment apparatus of the present invention.

FIG. 2 is a partially cutaway perspective view of an electrolysis treatment tank used in one embodiment of the present invention.

[Explanation of symbols]

10: Electrolysis treatment tank, 11: Metal waste material, 12: Cathode plate, 13: Anode plate, 14: Basket, 20: Solid-liquid separator, 30: Activated sludge treatment tank, 40 Solid-liquid separator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromitsu Saito             3075-11 Shimasu, Itako-shi, Ibaraki Toyo Riken Co., Ltd.             In the company (72) Inventor Yoshikazu Matsudo             904-A5-808 Komurocho, Funabashi City, Chiba Prefecture F-term (reference) 4D028 AB00 BA00                 4D061 DA08 DB15 EA06 EB04 EB14                       EB24 EB27 EB28 FA14 FA15

Claims (9)

[Claims] 1. An electrolysis treatment of a wastewater containing a large amount of pollutant components that can be aggregated and separated with aluminum ions or iron ions and a small amount of a solvent component that does not aggregate with aluminum ions or iron ions, containing aluminum and / or iron pieces. Activated sludge treatment of the first step of aggregating a large amount of pollutant components that can be aggregated and separated with aluminum ions or iron ions by electrolysis in the tank, the second step of separating aggregates, and the treatment wastewater from which the aggregates have been separated. A method for treating wastewater, comprising a third step of treating activated sludge in a tank. 2. A large amount of contaminant components that can be aggregated and separated with aluminum ions or iron ions contain a surfactant and / or a wax component, and the solvent component is water-soluble.
The method described. 3. The method according to claim 1, wherein the waste water is car wash waste water of an automobile. 4. In the first step, at least 7 of contaminant components that can be aggregated and separated with aluminum ions or iron ions.
The method according to claim 1, 2 or 3, wherein 0% by mass is aggregated. 5. The method according to claim 1, wherein the ratio of the waste water retention time of the first step and the waste water retention time of the third step is 1:20 or less. 6. A wastewater treatment apparatus comprising a large amount of pollutant components that can be aggregated and separated with aluminum ions or iron ions and a small amount of solvent components that do not aggregate with aluminum ions or iron ions, wherein the aluminum and / or iron pieces are removed. An electrolytic treatment tank containing the solid-liquid separation device for separating aggregates aggregated by contacting with aluminum ions and / or iron ions in the electrolytic treatment tank, and treating the treated wastewater from which the aggregates are separated Wastewater treatment equipment including activated sludge treatment tanks for. 7. A large amount of contaminant components that can be aggregated and separated with aluminum ions or iron ions contain a surfactant and / or a wax component, and the solvent component is water-soluble.
The described device. 8. The apparatus according to claim 6, wherein the waste water is car wash waste water. 9. The ratio of the wastewater capacity of the electrolysis treatment tank to the wastewater capacity of the activated sludge treatment tank is 1:20 or less.
The apparatus according to claim 1.