JPH081152A - Method and apparatus for removing oil in waste water - Google Patents

Abstract

PURPOSE:To remove easily and surely oil in waste water such as kitchen drainage containing oil (normal hexane extract) by a grease trap and to conduct the prevention of an offensive odor and preferable waste water treatment.. CONSTITUTION:Oil which was separated from water in the oil-water separation chamber 5 in a drainage receiving tank (grease trap) 1 is sucked with an oil suction nozzle 10 and removed by being adsorbed by an oil adsorbing body 13 which is filled in an oil adsorption chamber 12. Excessive water which was not adsorbed with the oil adsorbing body 13 is returned to the drainage receiving tank 1 or discharged to a drain system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method and apparatus for removing oil components from oil-containing wastewater in kitchen wastewater, food processing plants, gas stations, machine factories and the like.

[0002]

2. Description of the Related Art A considerable amount of oil (normal hexane extract) is contained in kitchen wastewater from hotels, restaurants, large-scale restaurants, inns, golf courses, service areas and the like. These kitchen wastewater and oil-containing wastewater from small-scale food processing factories, gas stations, etc. were sometimes discharged as they were, but now the regulations are stricter (animal and vegetable oil: 30ppm, mineral oil: 5ppm), and the minimum. However, it has become mandatory to install a grease trap (grease interceptor) and a retention device for separating contaminants.

The oil accumulated in the grease trap is regularly removed by vacuum suction or manual work.
It is supposed to be cleaned, but there are no human resources with specialized knowledge, and the oil that adheres or stays oxidizes and decomposes, giving off a strong foul odor (especially animal and vegetable oils). It has not achieved its intended purpose as a grease trap, for example, oil is released as it is with drainage, clogging drainage pipes and polluting rivers.

In addition, since the drainage amount of kitchen wastewater is uneven in time and the capacity of the device is relatively small, the drainagewater is discharged as it is during the daytime with almost no sedimentation treatment, and conversely at nighttime. Since it stays for a long time, there was a problem that a bad smell drifted to the seats in the early morning.

However, it is difficult to completely treat the oil (normal hexane extract) even in a full-scale biological treatment facility, and the present situation is to deal with it by prolonging the treatment time and increasing the treatment tank. It is almost impossible to decompose oil with a simple kitchen wastewater treatment system. However, if even the oil adhering to or staying in the grease trap can be sufficiently removed, the function as the grease trap can be fulfilled, and the foul odor that bothers employees and customers can be reduced.

From this point of view, the present inventor has developed a technique for installing an oil adsorbent in an oil / water separation chamber of a tank for receiving waste water (waste water receiving tank). By periodically exchanging the oil adsorbent, it is possible to remove the oil remaining in the grease trap. Further, by supplying the saponin-containing agent to the oil / water separation chamber or the water receiving chamber located on the upstream side of the oil / water separation chamber, deodorization or decomposition of oil adhering in the grease trap or adsorbed on the oil adsorbent can be favorably performed. It became so.

[0007]

However, in the case of kitchen drainage, there are many cases where a drainage water receiving tank is installed near the kitchen, mainly under the floor, etc., from the viewpoints of food waste removal and space restrictions. In this case, there are problems that it is difficult to replace the oil adsorbent due to locational restrictions, and a strong odor is generated during replacement. Further, even if the oil is adsorbed by the oil adsorbent, the oil remains in the drainage water receiving tank, and a malodor is constantly released and drifts in the kitchen. Similar problems may occur at food factories and gas stations.

[0008]

Therefore, the inventor of the present invention further researches and fills an oil absorption chamber provided separately from the oil-water separation chamber with an oil adsorbent, and sucks the oil accumulated in the oil-water separation chamber by vacuum. Then, we developed a technique to guide the oil to the oil absorption chamber where it is adsorbed. The oil absorption chamber has the effect of more complete separation of oil and water and the prevention of foul odor emission. For these purposes only, it may be attached to the drainage water receiving tank, but the efficiency of oil adsorbent replacement work is improved. When the purpose is also for such purposes, they may be independently installed at remote locations where work is easy.

Here, drainage which is the subject of the present invention means not only kitchen drainage of facilities such as hotels, restaurants, large-scale dining halls, inns, golf courses, service areas, etc., which provide food for tens to hundreds of people, It also includes oil-containing wastewater discharged from small-scale food processing plants, and miscellaneous wastewater from households in areas without sewage facilities. The amount of these wastewaters is relatively small, but the source of discharge is extremely large, and the amount of oil (mainly animal and vegetable oils) contained in the total amount of wastewater cannot be ignored. Wastewater containing mineral oil from machine shops and gas stations is also included in the wastewater targeted by the present invention.

Therefore, in the tank (drainage water receiving tank) referred to in the present invention, in addition to a single grease trap or a grease trap used in combination with separation / precipitation / retention treatment of wastewater, floating separation of oil in a wastewater treatment tank or the like is performed. Also included are those with a part that can. Then, a portion where oil can be separated is defined as an oil / water separation chamber, and an oil absorption nozzle is arranged above the oil / water separation chamber.
If there are conventional tanks, these tanks can be used as they are, with or without improvement of the portion where the oil absorption nozzle is arranged. Taking the kitchen drainage as an example, the size of the tank depends on the oil content, but in the case of the grease trap alone, it may be about 200 to 250 liters at a facility of 100 meals / day. The oil / water separation chamber is 1/3 to 2/3 of that.
A small capacity is enough.

Further, the tank of the present invention is provided with a water receiving chamber for receiving drainage and a treated water chamber for collecting and discharging treated drainage. A receiving basket can be installed in the water receiving room to separate vegetable scraps and other contaminants, and this receiving basket is taken out regularly (every day to several days) and the contents are discarded. A structure that can be cleaned is preferable. The wastewater is sent from this receiving chamber to the oil-water separation chamber, where the oil is floated and separated,
Water flows into the treated water chamber from the passage under the partition wall and is discharged to the outside of the apparatus. When aeration is performed in the oil / water separation chamber, the oil / water separation is performed better, and when the saponin-containing agent is added, the oil content is further decomposed. In the small one,
There is a two-chamber type in which the water receiving chamber and the oil / water separating chamber are combined, or the treated water chamber also serves as the oil / water separating chamber, but these can also be used in the present invention.

The oil absorption chamber has a watertight and airtight structure,
It is provided with a two-part structure or a lid part or a bottom part that can be opened and closed in order to fill the oil adsorbent in a removable manner. Then, while connecting the inflow pipe installed on the upstream side of the oil absorption chamber to the oil absorption nozzle located on the upper part of the oil / water separation chamber, the suction pump is installed on the downstream side (outflow side) of the oil absorption chamber to drain excess water. An outflow pipe for returning to the water tank or discharging to the drainage system is connected to a suction pump. When the oil absorption chamber is attached to the drainage water receiving tank, these pipes are short or omitted. If installed separately at separate locations, these pipes will extend to the installation site. It is preferable to connect the outflow pipe to the water receiving side of the drainage water receiving tank, if possible, because the oil leaked due to adsorption can be re-adsorbed.

The oil suction nozzle is located at the water surface (WL) of the oil / water separation chamber.
It is placed in contact with or below the surface of the water. The shape is preferably such that the width of the oil / water separation chamber is as wide as possible, but a narrower width may be moved in at least one of the front, rear, left and right directions. A wide object may be moved in the front-back direction. Further, it is usually arranged on the downstream side of the oil / water separation chamber. The operation of the oil suction nozzle may be continuous or intermittent. Alternatively, the floating of oil may be detected by some means, such as a sensor, and the oil suction nozzle may be operated for a predetermined time when the oil has accumulated to some extent, or it may be continuously or briefly stopped while the kitchen or factory is operating. It is conceivable that the timer is controlled so that it is operated intermittently with a pinch in between and stopped at night.

Next, as the oil adsorbent, pulp, polypropylene, or any other material having excellent adsorbability for oil content that does not adsorb water so much is made into a paper-like, cotton-like or non-woven fabric-like oil adsorbing sheet, or a cloth thereof. You can use an oil suction pad packed in a bag made of paper, non-woven fabric, net, etc. Instead of pulp or polypropylene, various types of activated carbon such as fibrous activated carbon, chaffed activated carbon, coconut activated carbon, etc., fibrous substances such as wood chips (sawdust), granular minerals such as slaked lime and sand, etc. You can use basically anything. The fibrous activated carbon is particularly excellent in oil absorption. When these oil adsorbents are packed and used in a net basket or a container made of a knit, a wire net, or a perforated metal plate, there is an advantage that the oil adsorbent can be easily put in and taken out from the oil absorption chamber and the hands are not soiled.

In order to reduce the suction resistance in the oil absorption chamber, it is preferable that the oil adsorbent has a low water permeation resistance.
From this point of view, a cloth, a non-woven cloth, a net, chaffed charcoal or other material having a large number of gaps is preferably used rather than a paper-like material that is clogged. However, the condition is that the oil absorption performance is excellent. The time for exchanging the oil adsorbent is not fixed depending on the scale of the facility, the content of food, the capacity of the oil absorption chamber, etc., and it is advisable to repeat the experiment to determine a sufficient period. Usually, it is good to design it so that it can be exchanged once every 1-2 weeks.

As described above, when the oil absorption chamber is separately provided, a large amount of oil is not accumulated in the oil / water separation chamber, so that when the oil absorption chamber is provided outside the kitchen, the generation of malodor in the kitchen is significantly reduced. However, oil cannot be prevented from adhering to the side wall of the oil / water separation chamber or the inner wall of the pipe (inflow pipe) to the oil absorption chamber. In addition, the oil adsorbed on the oil adsorbent is oxidized and
It still rots and gives off a bad smell. In order to solve these problems, when a saponin-containing agent is added to the waste water, the oil content is prevented from adhering to the wall surface or the like and the offensive odor is prevented, and a more comfortable processing environment is provided.

Saponin is a kind of glycoside contained in plants, and is a general term for making colloidal aqueous solution which is remarkably foamed like soap, and is found in many plants. The type of saponin used in the present invention is not limited, but from the viewpoint of cost and stable supply, it is preferable that the content of the saponin in the plant is large and the plant is present in a large amount and can be stably obtained. From this standpoint, saponins obtained from quillaja saponins, yucca, Japanese rafts, soybeans and the like are preferable. Among these, especially the soap tree that grows naturally in Chile, Bolivia, Peru, etc. in South America (scientific name: Quilaia saponaria Mol.
Quillaja saponin extracted from Rosaceae) is preferred. This is a triterpene type glycoside represented by the chemical formula 2 in which quillaic acid having the structure of the chemical formula 1 is used as an aglycone (a non-carbohydrate part of the glycoside), and its structure and analytical technique have been elucidated. This is because there are few saponins, and an extract with a relatively high saponin content can be obtained.

Embedded image

Embedded image

As the saponin-containing agent, an extract (including a solvent) extracted from a plant may be used as it is, or a purified product itself may be used. The extraction method may be an ordinary method and can be performed with a lower alcohol such as ethanol. Furthermore, a refined product or an extract may be used in the form of powder, granules, or tablets.

By the way, the present inventor has found that saponin is effective in the biological treatment process of sewage. This is because saponin is a glycoside and thus serves as a nutrient for microorganisms and has a high oxygen content. It is speculated that the efficiency of treatment is improved as a result of the fact that, as a result, they help the reproduction of microorganisms. Therefore, the present inventor also supplied the saponin-containing agent to the oil-water separation chamber in the present invention and observed the situation for several weeks, and it was confirmed that the oil was adsorbed neatly on the oil adsorbent and adhered to the wall surface. There was a phenomenon in which the bad smell was significantly reduced. It is considered that this is because saponin has a surface-active action, which reduces the surface tension of the treated water and accelerates the decomposition of oil. Moreover, the BOD, COD, and SS components in the wastewater, which had stagnated in the tank from night to morning, were significantly reduced compared to before.

The amount of the saponin-containing agent added varies depending on the concentration of the oil component in the wastewater, but is usually about 0.01 to 1.0 ppm in terms of the purified product in the wastewater. As for the method of addition, in the case of a liquid, a method of constantly dropping with a metering pump is preferable, and in the case of granules or the like, it is preferable to add the amount for one day in 2 to 3 portions. Although these methods are possible in large-scale facilities such as hotels, there are no dedicated personnel in facilities such as general households and small-scale restaurant industries, and there are no dedicated personnel for pump maintenance and concentration control. The reality is that it is difficult to get around. Moreover, if the concentration of saponin is lowered, the processing ability is lowered to reduce the effect, and if it is increased more than necessary, the cost is increased, which is not preferable.

In such a case, the saponin-containing agent is used as a sustained-release solid agent, and an appropriate number of the saponin-containing agent is put into the oil-water separating chamber or the water-receiving chamber or stored in the oil adsorbent. Good. As the sustained-release solid agent, for example, a solid agent obtained by mixing a base material such as wax that gradually dissolves in water with an extract or purified product of saponin can be considered. If an appropriate number of this is added after taking into consideration the degree of dissolution of the solid agent and after an appropriate number of days, there is an advantage that it is possible to easily maintain an appropriate saponin concentration without any trouble.

Further, the oil / water separation chamber may be equipped with a mechanism for blowing air into the oil / water separation chamber in order to assist the floating and emulsification of oil and to propagate microorganisms that decompose oil to some extent. Microorganisms include bacteria, filamentous fungi, actinomycetes, etc., and any type can be used as long as it can be used for grease trap. Incidentally, if these bacteria do not naturally occur, a separately cultivated one may be positively introduced.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the embodiments shown in the drawings. FIG. 1 is a plan view showing an example of a drainage / water receiving tank (a grease trap: a state in which a lid is omitted) and an oil absorption chamber according to the present invention, and FIG. 2 is a longitudinal section in a state in which the drainage / water receiving tank is covered. It is a figure. In the figure, drainage A from the kitchen is introduced into the water receiving chamber 3 of the drainage receiving tank 1 through the inlet 2.
Here, vegetable scraps and the like are separated by the receiving basket 4. Then, the wastewater sequentially reaches the oil / water separation chamber 5, where the oil component F in the water is separated and floated. Treated water B from which oil has been separated in the oil / water separation chamber 5
Is sent to the treated water chamber 8 through the passage 7 below the partition wall 6, and is discharged from the drainage water receiving tank 1 through the discharge port 9. still,
In the figure, WL indicates the water surface.

On the other hand, the oil F separated and floated in the oil / water separation chamber 5
Is sucked from the oil absorption nozzle 10, passes through the inflow pipe 11, reaches the oil absorption chamber 12 installed at a location apart from the drainage water receiving tank 1, and is absorbed by the oil adsorbent 13 filled in the oil absorption chamber 12. To be done. The oil adsorbent 13 used in this example is made of fibrous activated carbon, which is used as a knitted net bag 14
It is packed in and loaded into the oil absorption chamber 12. The suction by the oil suction nozzle 10 is performed by the suction action of the suction pump 15 provided on the downstream side of the oil suction chamber 12, that is, on the outflow side. Further, an outflow pipe 16 for returning the sucked extra water to the drainage water receiving tank 1 is connected to the suction pump 15. Code 17
Is a wire mesh for supporting the oil adsorbent 13.

Therefore, the treated water treated by the above apparatus is
The oil is almost completely removed, which greatly reduces the clogging of pipes and the pollution of rivers, and the separated oil can be easily treated to reduce the malodor generated in the kitchen. When the saponin-containing agent is added to the drainage water receiving tank 1, particularly the oil / water separating chamber 5 or the water receiving chamber 3, the effect of decomposing and deodorizing oil is excellent. Reference symbol T shown in the figure is a degradable solid saponin-containing agent. Further, when the aeration device 18 is incorporated in the lower portion of the oil / water separation chamber 5, the floating of the oil F and the like are promoted.

In the above embodiment, the oil absorption chamber 12 is replaced by the drainage water receiving tank 1
This is an example of installation at a place distant from each other, but in some cases, it may be preferable that both are close or integrated. 3 and 4 show another example used in such a case. In the case of FIG. 3, the oil absorption chamber 12 is attached to the outside of the drainage / water receiving tank 1, and in FIG. 4 the oil absorption chamber 12 is incorporated inside the drainage / water receiving tank 1, particularly in the oil / water separation chamber 5. is there. Reference numerals in each figure are the same as those in FIGS. 1 and 2.

[0027]

As described above in detail, in the method of the present invention, the oil component accumulated in the oil / water separation chamber of the waste water receiving tank is sucked and adsorbed by the oil adsorbent filled in the oil absorption chamber. Further, the device of the present invention embodies this method, and includes a closed oil absorption chamber attached to the drainage water receiving tank or independently provided at a remote place, and an oil absorption nozzle disposed above the oil / water separation chamber. The connection is made so that the floating oil content is adsorbed and removed by the oil adsorbent filled in the oil absorption chamber, and the excess water is discharged from the outflow pipe to the drainage receiving tank or drainage system.

Therefore, the following effects are produced. Cleaning management of the grease trap (drainage water receiving tank) becomes easy, and the disposal of the oil adsorbent can be done easily. Almost no foul odor is emitted during normal times, which improves the working environment. The normal hexane extract in the treated water decreases more than expected and prevents clogging of drainage pipes. BOD and other measured values also decrease, and the quality of the treated water discharged becomes good. In normal-scale kitchen wastewater treatment, the oil adsorbent needs to be replaced about twice a month, which requires little labor and cost and is extremely cost-effective. The oil absorption chamber can be easily installed as it is or by making a simple improvement to the conventionally installed grease trap. In that case, for example, in the case of a kitchen, the oil absorption chamber has an advantage that it can be installed at an arbitrary place where it does not interfere with the work in the outdoors or in the kitchen. When the saponin-containing agent is used, the oil content is decomposed and oxidation and putrefaction are suppressed, so that the malodor is further greatly reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a drainage water receiving tank and an oil absorption chamber according to the present invention.

FIG. 2 is a vertical sectional view of the same.

FIG. 3 is a schematic plan view showing another example.

FIG. 4 is a schematic vertical sectional view showing still another example.

[Explanation of symbols]

 1 Drainage water receiving tank 3 Water receiving chamber 5 Oil-water separation chamber 10 Oil absorption nozzle 11 Inflow pipe 12 Oil absorption chamber 13 Oil adsorber 15 Suction pump 16 Outflow pipe A Wastewater B Treated water F Oil component

Claims (3)

[Claims] 1. A method for removing oil in drainage, which comprises sucking oil accumulated in an oil / water separation chamber of a drainage water receiving tank and adsorbing it to an oil adsorbent filled in the oil absorption chamber. 2. The method for removing oil components from waste water according to claim 1, wherein the saponin-containing agent is supplied to the oil / water separation chamber of the waste water receiving tank or the water receiving chamber located upstream thereof. 3. An oil absorption chamber filled with an oil adsorbent so that it can be taken in and out, is attached to a drainage water receiving tank or is provided independently at a separate location, and an inflow pipe provided on the upstream side of the oil absorption chamber is used to separate oil and water. While connected to the oil absorption nozzle located in the upper part of the chamber, a suction pump is provided on the downstream side (outflow side) of the oil absorption chamber to return excess water to the drainage receiving tank or discharge it to the drainage system. A device for removing oil from wastewater, characterized in that the pump is connected to a suction pump.