JPS5841885B2 - Oil-containing wastewater treatment method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the treatment of oil-containing wastewater, and relates to a method and apparatus for removing oil from oil-containing wastewater.

In recent years, due to the remarkable development of the heavy chemical industry, especially the petroleum industry and petrochemical industry, the amount of wastewater from these plants has become enormous.

Among these wastewaters, if wastewater containing oil is disposed of as is, it will pollute seawater and oceans and have a serious impact on marine living systems.

Conventionally, various treatment methods have been tried to treat oil-containing wastewater, depending on the type of oil-containing wastewater, the amount to be treated, and the like.

Typical of the conventional treatment methods mentioned above are a method using a separator, especially a method by standing still, or an API method, a PPI method, or a CP method in which oil-containing wastewater is passed between multilayer parallel plates.
There are methods such as I method (for example, "Yekiru Handan", Sekiyu Shunjusha, 1
972).

These methods are suitable for the treatment of highly polluted wastewater and for preliminary treatment when performing advanced wastewater treatment to reduce oil content, and can treat relatively large volumes of wastewater, but they require a large site area. Or, it is not possible to process a large amount of wastewater in a certain amount of time by increasing the flow rate of treated water.

Furthermore, there are concerns about dirt on the surface of the parallel plates and blockage by debris, and the operation of the device is not easy, and furthermore, it is difficult to separate fine oil components.

In order to separate finer oils or emulsions, there are methods to remove oil by adding various salts, polymer flocculants, etc. to form aggregates, activated contamination methods that apply the assimilation ability of microorganisms, and various filters. There are methods such as using coalescer agents and adsorbents, but each requires the use of auxiliary materials such as chemicals, consideration must be given to preventing secondary contamination, and when microorganisms are used, operational management is difficult. When using filters and coalescers, pressure drop due to clogging,
Relatively frequent replacement of adsorbents, filters, etc. is required.

The present inventors have discovered a new and excellent method for treating oil-containing wastewater that is completely different from the conventional oil-containing wastewater treatment method as described above, and does not require the use of large equipment or auxiliary materials (processing agents). Ta.

The present invention involves passing oil-containing wastewater through a pipe having an orifice, extracting part of the oil-containing wastewater continuously or intermittently from the vicinity of the orifice, and treating the oil-containing wastewater with a lower concentration of oil than the oil-containing wastewater introduced downstream of the extraction point. This is a method for treating oil-containing wastewater, which is characterized by obtaining treated wastewater.

It is thus entirely unexpected and surprising that a treated wastewater with a reduced oil content can be obtained by passing the oil-containing wastewater through a tube having an orifice.

The wastewater treated by the method of the present invention is wastewater containing various unused or used oils in freshwater or seawater, and the oil components are usually mineral oils ranging from gasoline fractions to heavy oils,
Alternatively, the oil may be made of vegetable oil or the like, and the shape of the oil may be fine, for example, 50 μm or less.

Bilge wastewater (drainage that collects in ship engine rooms, etc.)
Specific examples include ballast wastewater, mineral oil-containing wastewater discharged from various machine factories, and wastewater from various oil refineries or oil depots.

The oil concentration in oil-containing wastewater is, for example: 3 ppm to 1.000
ppm, usually about 10 ppm to 100 ppm.

In the present invention, this oil-containing wastewater is passed through a pipe provided with an orifice, and the flow rate through the pipe is, for example, 0. ' 5 CrrL/sec to 15 m/secC The flow rate is usually 1 crrL/sec to 5 m/sec, and the optimum flow rate is selected depending on the pipe diameter or the size of the orifice hole υ, which will be described later.

The pipe through which the waste water passes is a normal tubular material, and a steel pipe is sufficient.

The inner diameter of the pipe varies depending on the processing amount, oil content, etc., but for example, the diameter is about 2α to 80CrIL, and usually about 2.5CrrL to 401cm.

The orifice used can be formed by installing an orifice plate with a suitable opening at any position in the tube.

The size of the orifice is selected appropriately depending on the pipe diameter.

There are no particular restrictions on the shape of the orifice, and a circular shape is usually employed.

The normal pipe diameter is the D1 orifice opening diameter.

For example, (Do/D)=o, o 1~0.8,
Usually (Do/D)=0.04 to 0.3 is adopted.

In the present invention, the orifice plate on the negative side may have two or more openings in the center, but in this case, the total area of those openings is the same as the area of one opening described above. Make sure they are equal.

In the present invention, a plurality of such orifice plates can be arranged in series in the tube.

A certain length, for example about 20 mm, is placed before and after the orifice plate.
It is preferable to have a straight pipe section of more than .

The method of the present invention involves passing wastewater through a pipe constructed as described above, and from the flow of wastewater passing through the pipe, a point in the vicinity of an orifice plate, for example, within a distance of 30, typically 5□ from the orifice plate. This can be done by continuously or intermittently extracting a portion of the orifice plate at a point upstream or downstream of the orifice plate within □□.

The above-mentioned extraction can be performed through an opening provided in the tube wall.

However, the orifice plate may be provided with a passage that opens at an arbitrary position on the inner surface of the orifice plate and communicates with the outside of the tube through the orifice plate, and the liquid may be extracted through this passage.

The size of the extraction port is not particularly limited, but an appropriate size is usually selected depending on the pipe diameter, for example, 115 to 1/10', usually 1/10 to 1/100 of the pipe diameter.

The amount of wastewater extracted from the outlet varies depending on the pipe diameter and the flow rate of the wastewater to be treated, but is usually about 115 to 11,500, for example, 115 to 1/10' of the amount of waste water introduced.

In the present invention, the concentration of oil in the wastewater extracted from this outlet is higher than the concentration of oil in the main stream that passes through the orifice and is obtained downstream.

Although it is not exactly clear why in the present invention, wastewater containing oil at a lower concentration can be obtained by passing the oil-containing wastewater through the orifice and extracting a portion of the wastewater from the vicinity of the orifice as a side stream. This is thought to be due to the drop in pressure and extra shear of the fluid as the wastewater passes through the orifice, creating a stagnation area with a higher oil content near the orifice.

Next, the present invention will be explained in more detail with reference to the drawings.

In Figures 1 and 2, 1 is a pipe through which wastewater passes;
2 is an orifice, 3 is an opening of the orifice, 4 is an outlet downstream of the orifice, 5 is an outlet upstream of the orifice, 6 is a wastewater outlet pipe from the outlet downstream of the orifice, and I is a wastewater outlet pipe from upstream. It is.

The wastewater to be treated is usually passed through the pipe in the direction of the arrow in the diagram.

Waste water is typically supplied into the pipes by a pump (not shown) under pressure, for example 0.1 to 20 Ky/ffl.

The waste water passes through the orifice, during which part of the fluid is withdrawn intermittently or continuously through the openings 4, 5 or both openings 6 or 7.

This results in treated wastewater with a lower oil content coming downstream of the pipe.

The wastewater extracted from the opening has a higher oil content than the supplied wastewater, and the flow rate is much lower than that of the supplied wastewater, so another method is used to remove the oil and reduce the oil content to a concentration that can be disposed of. remove.

Of course, the side stream can be treated with the same orifice mechanism as in the other embodiment of the present invention to reconcentrate the oil concentration.

This reconcentration is preferably carried out by recycling the side stream.

FIG. 3 is a flowchart showing an example of reconcentration by recirculating side streams.

In FIG. 3, a tube 1 has a plurality of orifice plates 2.2', 2", 2", . . . arranged in series in the longitudinal direction of the tube at appropriate intervals. orifice plate 2,
There are extraction pipes 6, 6', 6", 6", 6, 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6", 6"...
. . . and 7, 7', 7", 7"', . . . are provided.

The oil-containing wastewater extracted from the vicinity of the second-stage orifice τ by the extraction pipes 6' and 7' is collected in the reflux pipe 8', and is sent from the pump 9 to the upstream point of the orifice 2, which is one stage upstream. , the reflux is returned to the tube 1 via the reflux inlet tube 10.

Similarly, the waste water extracted from the vicinity of the third stage orifice plate 2'', the fourth stage orifice plate 2'', etc. “
A large amount of water is flowed to the upstream point of...

In this way, the oil content of the waste water withdrawn from the vicinity of the first stage orifice plate 2 via the withdrawal pipe 6.7 is concentrated to a high oil content.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Oil-containing wastewater was treated using equipment having the structure shown in FIG.

However, the inner diameter of the pipe is 2.5 crr, the hole diameter of the orifice is 2.0 crr, and the side flow outlet is 1 crr in diameter.

Table 1 shows the results of passing various oil-containing wastewaters through the pipes at predetermined flow rates.

However, the average 0
．． A portion of the waste water was extracted at 04/:/min.

The above results show that the method of the present invention is an excellent and efficient method for treating oil-containing wastewater without using expensive and extensive equipment or auxiliary materials.

Example 2 Oil-containing wastewater was treated using equipment having the structure shown in FIG.

However, the inner diameter of the tube is 11.4 CrrL, and the orifice diameter is 3. Q mm, side flow outlet has a diameter of 1.0
It is C11L.

Table 2 shows the results of passing various oil-containing wastewaters through the pipes at predetermined flow rates.

However, the side flow port was located in the tube wall 20 mrn away from the orifice, and the side flow was extracted through pipe 6 or pipe 7 at an average rate of 0.2 t/min.

The above results show that the method of the present invention is superior as in Example 1.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one example of the device of the present invention, and FIG. 2 is a sectional view showing another example. FIG. 3 is a schematic diagram illustrating how a large number of devices of the present invention are used in series. In each drawing, parts indicated by symbols are as follows. 1...Tube, 2, 2', 2'', 2'''...
Orifice 3.3/, 3//, 3///...
Orifice opening, 4, 5... Waste water outlet, 6, 6', 6". 6"'... Waste water outlet pipe, 7, 7', 7", 7
"'...--Wastewater outlet pipe, 8, 8', 8"...
・Recirculation pipe, 9,9γ9″・・・Pump, io, 1o
', io"...reflux inflow pipe.

Claims (1)

[Scope of Claims] 1. Oil-containing wastewater is passed through a pipe having an orifice, and a portion of the oil-containing wastewater is extracted continuously or intermittently from near the orifice, and from downstream of the extraction point, oil content is higher than that of the introduced oil-containing wastewater. A method for treating oil-containing wastewater, characterized by obtaining treated wastewater with a low concentration of oil. 2. Claim 1, in which oil-containing wastewater is passed through a pipe having a plurality of orifices spaced apart in rows in the longitudinal direction of the pipe, and a portion of the oil-containing wastewater is extracted from the vicinity of each orifice. The method described in section. 3. The method according to claim 2, wherein the wastewater extracted from the vicinity of each orifice downstream of the second stage and below is returned to the upstream of the orifice one stage upstream from each orifice. 4. A treatment device for oil-containing wastewater, comprising a pipe through which oil-containing wastewater passes, an orifice provided in the pipe, and a means for extracting a portion of the oil-containing wastewater that opens in the pipe near the orifice. 5 The means for extracting part of the oil-containing wastewater is through an orifice.
The apparatus according to claim 4, which opens at a position between 30 ( ) toward the upstream and downstream. 6 The means for extracting a part of the oil-containing wastewater opens at the surface of the orifice plate, and the means for extracting a part of the oil-containing wastewater opens at a position in the orifice plate. 7. The device according to claim 4, which is a passageway that communicates with the outside of the pipe through the pipe. 5. The device according to claim 5. 8. Claim 4, comprising a plurality of orifices arranged in series at intervals in the longitudinal direction of the pipe, and means for extracting a portion of the oil-containing wastewater in the vicinity of each orifice. The device according to items 7 to 7.9 Extending outside the tube from the opening in the outer wall of each extraction means provided near each downstream orifice of the second stage and below,
It has a side flow pipe for refluxing the extracted oil-containing wastewater, and the side flow pipe passes through a reflux pump and is connected to a reflux inlet provided on the pipe wall at a position upstream of the orifice, one step upstream from the orifice. 9. The device according to claim 8, wherein the device is connected to a through hole.