JPH09131588A - Waste water treatment for kitchen sink and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent environmental degradation and to effectively utilize water by recovering waste water from the drain port of a kitchen sink and purifying the water by reaction of a photocatalyst, then discarding or recycling the water. SOLUTION: This septic device connected via an odor trap 7 to the kitchen sink 1 consists of a waste water tank 8, a purified water tank 13, a pump unit 9, a reaction vessel 10, a separating vessel 11, etc., and is so piped as to recycle the water from the purified water tank 13. The sink 1 is provided with a cage type container 4 for easily replacing a filter 5. At the time of a waste water treatment, titanium dioxide powder as the photocatalyst is added to the water and while the powder is suspended in the reaction vessel 10, the water is kept stirred and is irradiated with UV rays by an ultra-high pressure mercury lamp. The water is then passed through the electret filter, by which the titanium dioxide powder is filtered and, thereafter, the water is sent to the separating vessel 11, where water content and oil-component are fractionated by a hollow fiber module. The treated water is returned to the purified water tank 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wastewater treatment. More specifically, the wastewater is collected from a drain of a kitchen sink, directly purified, and the purified water is discarded or recycled for use. The present invention relates to a wastewater treatment method and a purification apparatus thereof, which prevent wastewater containing oil from flowing into sewage or a septic tank to pollute the environment and significantly reduce the cost of tap water. .

[0002]

2. Description of the Related Art Interest in river and ocean purification has increased in recent years, and various efforts have been made. In particular, strict water quality restrictions are imposed on large-scale wastewater discharged from factories, which has been regarded as a problem, and corporate efforts are being made. There are many examples of improved water quality in rivers, although it is still inadequate due to its effects. In addition, sewers and septic tanks are becoming more widespread as living standards improve. As a result, the wastewater that had previously flown directly into the river will be purified. However, it is hard to say that this is still perfect when viewed nationwide. Moreover, as it was examined in detail, it became clear that domestic wastewater, which had not been considered a problem until now, was a major cause of water pollution. Especially as the content of meals becomes Westernized, a large amount of wastewater is discharged from the kitchen sink as oil-containing wastewater emulsified with detergents and other surfactants. Has become. It is predicted that these will emerge as environmental problems in the future, it is necessary to take measures before that, and it is well known that water is a limited resource, so it is recommended to reuse it. It was quite natural that it would be widely demanded in the future.

However, the conventional wastewater treatment for kitchen sinks is mainly a filter for removing garbage such as vegetable waste from the wastewater, or a large-scale biological treatment device is installed to treat all the garbage and turn it into sewage. There are only the two extremes of spilling. It is obvious that the large-scale equipment can be installed only in a special place such as a large restaurant or a kitchen in a hotel, and the biological treatment requires space and time, and the temperature and other operating conditions are difficult. In addition, although the simple method of removing solids with a filter does not reduce the load on sewage treatment, it did not reach far to the targeted improvement of water quality.

Recently, a wastewater treatment using an oil fence-specific oil adsorbent and a chip for capturing an emulsion has been proposed (JP-A-7-171563). However, these chips have a fatal drawback that they absorb all the water in the emulsion form and immediately swell and become saturated. It is rather rare to run oil alone as a kitchen sink drainage, most are in the emulsion form mixed with detergent, and the amount of water used for washing and rinsing is large, so the oil adsorbent immediately has an adsorption capacity. It will not be able to absorb its emulsion and perform its function. In order to achieve the purpose by this method, it is necessary to replace and continue to mount a huge amount of chips one after another, which is difficult to put into practical use economically and operationally.

[0005]

In view of the above problems, the present invention relates to a kitchen sink drainage containing an oil-containing emulsion, which decomposes the emulsion, separates it into water and oil, discards only the oil, and puts it in water. It is an object of the present invention to provide an economical, convenient and rational wastewater treatment method and device that can purify oil without leaving oil and reuse the water as much as possible.

[0006]

In order to achieve the above object, the present invention collects drainage from a drain of a kitchen sink,
The present invention provides a wastewater treatment method and a purification device for discarding or recycling it after purifying by a photocatalytic reaction.

Hereinafter, the present invention will be described in detail.

The present invention is a method and apparatus for purifying the drainage of a kitchen sink discharged when washing dishes, cookers, ingredients, etc. in hotels, various restaurants, homes, etc.
After removing solids such as meat pieces, vegetable scraps, and fish bones with a filter, the wastewater mixed with oil, detergent, and water-soluble organic matter is purified by chemical decomposition.

In the present invention, the most important point is to install a compact apparatus for purifying kitchen sink wastewater in an emulsion state where oil-water separation is difficult into recyclable purified water. Therefore, the purifying device in the present invention separates the surfactant, which is a constituent of the emulsion, by combining the oil content and the water with the photocatalytic oxidation reaction to lose the surface activity effect and separates it into two layers of water and oil. It consists of a reaction tank that exerts various sterilization effects and a separation tank that subsequently separates oil and water.

The term "kitchen sink drainage" as used in the present invention refers to all drainage water such as rinse water used for washing vegetables and tableware, which flows out to the kitchen sink drainage port. The water to be treated is stored in a drain tank through a drain port and then sent to a reaction tank.

The photocatalyst used in the reaction tank includes titanium dioxide, tungsten trioxide, zinc oxide, iron oxide,
Metal oxides such as strontium titanate, metal sulfides such as cadmium sulfide, zinc sulfide and indium sulfide, metal selenides such as cadmium selenide and zinc selenide, metal phosphide such as germanium phosphide and indium phosphide Etc., and any known ones such as those carrying a metal and metal oxide such as platinum, rhodium, ruthenium, copper and iron on these photocatalysts. Of these, titanium dioxide is particularly preferable, and the reasons therefor include catalytic activity, safety, low cost, chemical stability, etc., but the invention is not limited thereto.

The photocatalyst may be used in any form. For example, a method of dispersing in powder form or granular form, a film form, a porous form,
Examples include, but are not limited to, a method of processing into a fibrous form or a method of supporting the fibrous form on the product, a method of forming a processed product in the form of a honeycomb or a mesh, and the like. Since the active surface area for the reaction is large, the catalytic activity is highest in the powder form, but the fine particles are difficult to separate from the liquid and difficult to use. As a filter in that case, it is preferable to use an electret filter which electrically adsorbs fine particles to prevent passage thereof and keeps low pressure loss for passage of an aqueous solution. The electret filter has different charges on the front and back sides and is in the form of a non-woven fabric, and has both the electric adsorption of fine particles, which is the effect of the electret, and the filter effect by the entanglement of fibers, which is the effect of the non-woven fabric. Regarding the average fiber diameter of the fibers constituting the filter, for example, if the particle diameter of the fine particles is about several μm,
The fiber system is preferably 30 μm or less, more preferably 20 μm or less.
μm or less. Further, at a submicron-order level where the particle diameter is finer, the average fiber diameter of the fibers is preferably 3 μm or less, more preferably 2 μm or less. This is because the smaller the fiber diameter, the more the number of fibers per unit volume increases dramatically and the non-woven fabric becomes denser.
This is because it contributes to the high performance that the blocking rate increases without changing the porosity, that is, there is no leakage of fine particles even though the flow rate is large at low pressure. In addition, a small fiber diameter results in a large specific surface area, and a large area for causing electric adsorption also improves the performance.

When the fiber is made into a non-woven fabric, the basis weight is 20 g /
It is preferably m ² or more and 50 g / m ² or less. If the basis weight is too small, the probability of contact between the fine particles to be captured and the fiber becomes low, leaks increase, and the rejection rate decreases. On the other hand, if the basis weight is too large, the flow of the aqueous solution is obstructed, the pressure loss is applied, and the permeation flow rate is reduced, which makes it difficult to use as it is in a target series of flow systems.

The method of filtering the sheet so that it can be incorporated into the apparatus is arbitrary. The easiest method is to use resin, metal, or any other type of frame that can be attached to the equipment, but the method is not limited to this. Also, of course, there is no problem even if a plurality of sheets are used in a pile.
If the flow rate / flux is large and there is a problem with the sheet strength, there is no problem in using reinforcing measures such as attaching reinforcing sheets or attaching reinforcing materials such as wire mesh and plastic mesh.

This reaction tank requires a lamp that emits a light beam for exciting the photocatalyst. Any wavelength may be used as long as it includes a wavelength (visible and / or ultraviolet) that causes charge separation of the photocatalyst. For example, filament lamps such as incandescent lamps, mercury lamps, high-intensity discharge lamps such as xenon lamps, fluorescent lamps, black lights, fluorescent lamps such as germicidal lamps, artificial light sources such as laser light, or even the form of the device Sunlight can be used. Further, it is of course possible to simultaneously use an artificial light source as an auxiliary light source for sunlight.

Next, known materials and methods are used for the separation tank for separating oil and water from the treatment liquid in which the surfactant is decomposed in the reaction tank. Examples include, but are not limited to, a floating separation method, a centrifugal separation method, a coarse particle separation method using a coalescer, an adsorption method using an oil adsorbent, and a membrane separation method. However, the membrane separation method is preferable in consideration of a large flow rate and processing accuracy. The separation membrane may be any commonly known membrane, but it is easy to systemize without the need for a pressure device for water passage, and it is an ultrafiltration membrane or a membrane that allows water to pass but not particulates or oil. Precision filtration membranes are preferred. The pore diameter is 1 nm or more and 10μ
It is preferably m or less, and more preferably 1 nm or more and 1 μm or less. If the pore size is too small, the water pressure loss will be large, and the clogging of the membrane will also increase, and if it is too large, leakage of impurities will be observed, so the above range is preferred. The form of the membrane may be any of commonly used flat membranes, spiral membranes, hollow fiber membranes, pleated membranes, etc., but it is possible to increase the filtration area with a compact device and to have good backwashability. Hollow fiber membranes are preferred because they are suitable for use as filtration membranes or precision filtration membranes.

The material is not particularly limited as long as it can be molded into a hollow fiber membrane. For example, known polymer materials such as cellulose-based, polyamide-based, polysulfone-based, polyolefin-based and polyacrylonitrile may be mentioned. The material can be appropriately selected according to the requirements for use, and for example, polyacrylonitrile can be selected if high strength is required, and polyolefin series can be selected if high hydrophobicity is desired.

As shown in FIG. 1, for example, the purification apparatus of the present invention comprises at least parts such as a drainage tank 8, a water purification tank 13, a pump unit 9, a reaction tank 10 and a separation tank 11, and water is recycled again from the water purification tank. It is preferably plumbed for use. Also, there is no problem in providing other functions. For example, it is very preferable to place a filter 5 for preventing solids from mixing and a basket-type container 4 which can be easily replaced in the preceding stage, and an anti-odor trap 7 for a backflow odor from piping.
It is also preferable to put it behind. The basket-type container may be of any type depending on the type of solid matter to be discharged, but a basket-like container with a handbag as shown in FIG. 2 is preferable because it is easy to use. The material is not limited, and may be metal such as stainless steel that does not easily rust, copper that has an antibacterial effect, or strong and inexpensive plastic. The filter is also preferably one that can trap solids as much as possible and has low water resistance, and is not particularly limited. And of course it is not limited to these.

There are no particular restrictions on the installation location of the purifying apparatus of the present invention, but it is reasonably preferable that it can be installed under the sink. For drainage, it is preferable that the conventional drainage pipe is used as it is, and the drainage port and the processing device are directly connected to each other so that the drainage can be collected. It is preferable that the wastewater collected from the drainage outlet is sent to the reaction tank after being filtered by a dust-removing filter. In that case, it is preferable to constantly send a constant amount by a pump or the like because it is difficult to apply a load to the reaction tank.

In the present invention, the waste water to be treated is not limited at all. It is a wastewater containing water discharged from kitchen work, animal oil, vegetable oil, and detergent (surfactant), and does not require any special pretreatment. However, there is no problem in performing a pretreatment that is effective for this purpose, such as a filter for filtering solid matter or addition of an antifoaming agent.
Examples will be shown below, but the present invention is not limited thereto.

[0021]

【Example】

Example 1 A simulated kitchen drainage (surface tension 28 dyn / cm) 2000 m in which 5 ml of a kitchen detergent (“Yashinomiya detergent” manufactured by Saraya) was used to wash a pottery coated with 10 ml of salad oil.
The oil-water separation treatment was performed for 1. First, drainage 13
Place 00 ml in a stainless steel reaction tank, add 0.2 g of titanium dioxide powder (MC-90: Ishihara Sangyo Co., Ltd.), continue stirring while suspending, and irradiate ultraviolet rays with an ultra-high pressure mercury lamp installed in the reaction tank. And reacted for 3 hours. After that, the water passed through the electret filter and filtered with titanium dioxide powder is sent to a separation tank by a pump,
The hollow fiber module separates water and oil,
The treated water was returned to the purified water tank.

As a result of measuring the surface tension of the obtained treated water, the surface tension was improved to 50 dyn / cm.

Further, this treated water was used as it was, and a detergent was added to carry out washing again, but there was no problem and it was possible to sufficiently reuse.

Comparative Example 1 For 2000 ml of simulated drainage water similar to that in the example, oil absorbent chips (“Wosep”: Toray Fine Chemical Co., φ4 × 0.2 cm) were placed in a basket-like container for a kitchen sink (φ1).
The treated water after pouring 50 sheets tightly on the bottom of (4 × 15 cm) was examined. As a result, the treated water is about 180
It was 0 ml, and the rest was absorbed by the oil absorbent. The surface tension of the treated water was 29 dyn / cm, and oil-water separation did not occur at all.

From these results, it is possible to purify the waste water discharged from the kitchen by the water treatment device utilizing the emulsion decomposition performance of the photocatalyst and reuse it, and to take measures against the environmental problems and the effective use of water. It turned out to be very effective.

[0026]

EFFECTS OF THE INVENTION By using the method of the present invention, the wastewater discharged from the kitchen is purified and it is possible to recycle it. As a result, the amount of emulsion oil-containing wastewater that had been flushed directly into sewage and septic tanks has been reduced, and even when water shortage has not been seen as a problem, it contributes significantly to environmental problems that will continue to increase. it can.

On the other hand, since water is recycled and used, it is possible to save water charges and reduce costs.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system flow of kitchen wastewater treatment of the present invention.

FIG. 2 is a drawing showing an example of the basket type container in FIG.

[Explanation of symbols]

 1: Kitchen Sink 2: Drainage Port 3: Packing 4: Basket-type Filter Container 5: Filter 6: Water Stopper 7: Odor Trap 8: Drain Tank 9: Pump Unit 10: Reaction Tank 11: Separation Tank 12: Oil Waste Liquid Removal 13: Purified water tank 14: Recycled water 15: Waste water 16: Handbag 17: Mesh basket

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C02F 1/58 ZAB C02F 1/58 ZABC

Claims (10)

[Claims] 1. The drainage is collected from the drain of the kitchen sink,
A wastewater treatment method in which wastewater is recycled after being purified by a photocatalytic reaction. 2. The drainage is collected from the drain of the kitchen sink,
A wastewater treatment method in which surface-active substances are decomposed by a reaction of a catalyst and purified by separating oil and water, and then discarded or recycled. 3. The wastewater treatment method according to claim 2, wherein the photocatalyst is titanium dioxide. 4. The wastewater treatment method according to claim 2, wherein the photocatalyst is used in the form of powder or particles dispersed in water. 5. The wastewater treatment method according to claim 2, wherein the photocatalyst has a film shape, a porous shape, a fibrous shape, a honeycomb shape, or a mesh shape. 6. The wastewater treatment method according to claim 2, wherein a lamp that emits a light beam for exciting the reaction by the photocatalyst is used. 7. The wastewater treatment method according to claim 1, wherein the purification method includes a separation tank by membrane separation. 8. The wastewater treatment method according to claim 7, wherein the membrane used for the membrane separation is a hollow fiber membrane. 9. An apparatus using the purification method according to claim 1. 10. The device is located in the space under the kitchen sink and is directly connected to the drain port.
An apparatus according to claim 1.