JP6999255B1 - Wastewater treatment system and its operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wastewater treatment system for treating oil-containing wastewater. SOLUTION: A raw water tank (1) in which oil-containing waste water is stored, a first filter membrane device (2) for filtering oil-containing waste water in a raw water tank (1) to obtain first filtered water, and the first filtered water are stored. An oil-impregnated wastewater treatment system including a second filter membrane device (4) that filters the first filtered water of the first filtered water tank (3) and the first filtered water tank (3) to obtain the second filtered water. [Selection diagram] None

Description

The present disclosure relates to a wastewater treatment system capable of treating oil-containing wastewater and an operation method thereof.

Wastewater discharged from factories in various fields contains mineral oil, miscellaneous oil, wax, surfactants, suspensions, etc., and cannot be drained into sewage as it is, and must be treated.

In Patent Document 1, a surfactant having an HLB of 10 to 15 is added to oil-containing wastewater in an amount of 2% to 10% with respect to the oil content, and the mixture is stirred to form an oil droplet type in water, and then the emulsion is filtered through a ceramic filter. Also, an invention of a method for treating oil-containing wastewater, which comprises treating the filtered water with a reverse osmosis membrane, is described (the scope of the patent claim).
According to the above invention, it is described that treated water having an oil concentration and a surfactant concentration of 1 ppm or less can be obtained for a long period of time by preventing a decrease in the separability of a ceramic filter and a reverse osmosis membrane (paragraph number 0050). ).

In Patent Document 2, the oil-impregnated waste liquid is supplied to a pipe or stored in a storage tank, and the waste liquid supplied to the pipe or stored in the storage tank is dissolved or dispersed in an aqueous phase by pretreatment by supplying a chemical, and described above. An invention of a method for treating an oil-containing waste liquid, which comprises concentrating under reduced pressure in order to obtain a condensed water and a concentrated liquid from the waste liquid after the pretreatment, is described (claims).
According to the above invention, it is described that a waste liquid treatment method and an apparatus thereof capable of efficiently and easily treating oil-containing waste liquid without requiring frequent maintenance of the apparatus can be provided.

Japanese Unexamined Patent Publication No. 4-210289 WO2017 / 183236

It is an object of the present disclosure to provide a wastewater treatment system capable of treating oil-containing wastewater and an operation method thereof.

The present disclosure discloses a raw water tank (1) in which oil-impregnated waste water is stored, a first filter membrane device (2) that filters oil-containing waste water in the raw water tank (1) to obtain first filtered water, and stores the first filtered water. In an oil-impregnated wastewater treatment system equipped with a second filter membrane device (4) that filters the first filtered water of the first filtered water tank (3) and the first filtered water tank (3) to obtain the second filtered water. There,
The first filtration membrane device (2) has a separation membrane selected from a tubular RO membrane and a tubular NF membrane, and the second filtration membrane device (4) has a spiral RO membrane.
The raw water tank (1) and the first filtration membrane device (2) are connected by a raw water line (11) equipped with a first circulation pump (20).
The first filtration membrane device (2) and the first filtered water tank (3) are connected by the first a filtered water line (12).
The first filtration membrane device (2) and the raw water tank (1) are connected by the first concentrated water line (13).
It has a first circulation line consisting of a raw water tank (1), a raw water line (11), a first filtration membrane device (2), a first concentrated water line (13) and a raw water tank (1).
The first filtered water tank (3) and the second filtration membrane device (4) are connected by a first b filtered water line (14) equipped with a second circulation pump (21).
The second filtration water sampling line (15) is connected to the second filtration membrane device (4), and the second filtration water sampling line (15) is connected.
The second filtration membrane device (4) and the first filtered water tank (3) are connected by the second concentrated water line (16).
A second circulation line consisting of a first filtered water tank (3), a first b filtered water line (14), a second filtration membrane device (4), a second concentrated water line (16) and a first filtered water tank (3). It provides an oil-impregnated wastewater treatment system and an operation method thereof.

Further, in the present disclosure, a raw water tank (31) in which oil-containing waste water is stored, a pretreatment filter membrane device (32) for filtering oil-containing waste water in the raw water tank (31) to obtain pretreated water, and the pretreated water are stored. The pretreated water tank (33), the first filter membrane device (34) that filters the pretreated water in the pretreated water tank (33) to obtain the first filtered water, and the first filtration that stores the first filtered water. An oil-containing wastewater treatment system equipped with a second filter membrane device (36) that filters the first filtered water of the water tank (35) and the first filtered water tank (35) to obtain the second filtered water.
The pretreatment filtration membrane device (32) has a UF membrane or an MF membrane, and the first filtration membrane device (34) has a separation membrane selected from a tubular RO membrane and a tubular NF membrane, and a second. The filtration membrane device (36) has a spiral RO membrane,
The raw water tank (31) and the pretreatment filtration membrane device (32) are connected by a raw water line (41) equipped with a pretreatment circulation pump (50).
The pretreatment filtration membrane device (32) and the pretreatment water tank (33) are connected by the first pretreatment water line (42).
The pretreatment filtration membrane device (32) and the raw water tank (31) are connected by the pretreatment concentrated water line (43).
It has a pretreatment circulation line consisting of a raw water tank (31), a raw water line (41), a pretreatment filtration membrane device (32), a pretreatment concentrated water line (43) and a raw water tank (31).
The pretreatment water tank (33) and the first filtration membrane device (34) are connected by a second pretreatment water line (44) equipped with a first circulation pump (51).
The first filtration membrane device (34) and the first filtered water tank (35) are connected by the first a filtered water line (45).
The first filtration membrane device (34) and the pretreatment water tank (33) are connected by the first concentrated water line (46).
A first circulation line consisting of a pretreatment water tank (33), a second pretreatment water line (44), a first filtration membrane device (34), a first concentrated water line (46) and a pretreatment water tank (33). Have and
The first filtered water tank (35) and the second filtration membrane device (36) are connected by a first b filtered water line (46) equipped with a second circulation pump (52).
The second filtration water sampling line (47) is connected to the second filtration membrane device (36), and the second filtration water sampling line (47) is connected.
The second filtration membrane device (36) and the first filtered water tank (35) are connected by the second concentrated water line (48).
A second circulation line consisting of a first filtered water tank (35), a first b filtered water line (46), a second filtration membrane device (36), a second concentrated water line (48) and a first filtered water tank (35). It provides an oil-impregnated wastewater treatment system and an operation method thereof.

According to the wastewater treatment system of the present disclosure and its operation method, stable wastewater treatment can be performed for a long period of time while maintaining high filtration performance.

The figure which shows the wastewater treatment flow including the wastewater treatment system which is one Embodiment of this disclosure. The perspective view of the filtration membrane element which can be used in the 1st filtration membrane apparatus of the wastewater treatment system of this disclosure. FIG. 3 is a plan view of a filtration membrane element set in which a plurality of filtration membrane elements shown in FIG. 2 are combined. FIG. 3 is a perspective view of a filtration membrane element set in which a plurality of filtration membrane elements shown in FIG. 3 are housed in a cylindrical case housing. However, it is displayed so that the inside that cannot be actually seen can be seen. The figure which shows the wastewater treatment flow including the wastewater treatment system which is another embodiment of this disclosure. The figure which shows the wastewater treatment flow including the wastewater treatment system of the comparative example.

[First wastewater treatment system shown in FIG. 1]
The first wastewater treatment system will be described with reference to FIG.
Oil-containing wastewater is stored in the raw water tank 1. The raw water tank 1 is provided with a temperature control device (not shown), a thermometer (not shown), and a water level gauge (not shown) for adjusting the internal raw water temperature, if necessary. Can be done.

The oil-containing wastewater is wastewater containing a water-soluble oil, a surfactant and the like, and is, for example, wastewater having a COD of 6000 mg / L or more, a BOD of 5000 mg / L or more, and n-hexane of 1000 mg / L or more.
The oil-impregnated wastewater is sent from the oil-impregnated wastewater source to the raw water tank 1 by the oil-impregnated wastewater line 10 and stored. A pre-filter for removing large foreign substances such as metal pieces can be installed in the oil-impregnated wastewater line 10.
As the oil-impregnated wastewater source, those collected in a wastewater pit (drainage tank) into which oil-impregnated wastewater generated in various factories or the like flows can also be used.
The wastewater pit may be connected to the bottom of a discharge line for discharging a sediment such as gravel or sand, or a sediment when a flocculant is added.
The type and concentration of the oil in the oil-containing wastewater are not particularly limited, and for example, the components are the same as the amount of the n-hexane extract described in JP-A-2003-93803, and the same concentration range is used as a reference. Can be done.
If necessary, one or more chemicals selected from a surfactant, a flocculant, and an adsorbent can be added to the oil-containing wastewater in the wastewater pit.

The first filtration membrane device 2 is for filtering the oil-containing wastewater of the raw water tank 1 to obtain the first filtered water.
The raw water inlet of the raw water tank 1 and the first filtration membrane device 2 is connected by a raw water line 11 provided with the first circulation pump 20, but if necessary, it is between the raw water tank 1 and the first filtration membrane device 2. You can also install a pre-filter.
The concentrated water outlet of the first filtration membrane device 2 and the raw water tank 1 are connected by a first concentrated water line 13.
It has a first circulation line including a raw water tank 1, a raw water line 11, a first filtration membrane device 2, a first concentrated water line 13, and a raw water tank 1. An on-off valve (opening / closing valve) such as a solenoid valve can be installed in each of the first circulation lines as needed.

The first filtration membrane device 2 is preferably a device including a tubular RO membrane and a tubular NF membrane as a separation membrane, and the tubular RO membrane and the tubular NF membrane made of cellulose acetate are oil-containing waste water. It is more preferable because the decrease in the processing amount is suppressed when the treatment is performed.
As the first filtration membrane device 2 including the tubular RO membrane and the tubular NF membrane, the ones shown in FIGS. 2 to 4 can be used.
The first filtration membrane device 2 shown in FIG. 2 is, for example, a filtration membrane element 140 in which a tubular RO membrane or a tubular NF membrane 142 is arranged in a porous support tube 141.
The porous support tube 141 is made of a synthetic resin (for example, fiber reinforced resin) or a metal (for example, stainless steel), and a large number of holes 143 penetrated in the thickness direction are dispersedly arranged.
The tubular RO film or the tubular NF film 142 may have an RO film or an NF film formed inside a support tube made of a non-woven fabric, paper, or the like.
The inner diameter of the tubular RO membrane or the tubular NF membrane 142 can be adjusted according to the concentration (solid content concentration) of the water to be treated, and can be, for example, in the range of 5 to 15 mm.
In the tubular RO membrane or tubular NF membrane 142, since the flow path of wastewater is large, the membrane is difficult to block, and the inflow of wastewater also flows in the direction of peeling the membrane surface blockage, so that aggregates are present. Suitable for wastewater treatment.

The first filtration membrane device 2 shown in FIG. 3 is a filtration membrane element set 150 in which a plurality of filtration membrane elements 140 are connected to form one.
In the filtration membrane element set 150, among the filtration membrane elements 140 arranged in series, adjacent filtration membrane elements 140 are connected to each other by a U-shaped tube 151. Other connecting methods can be used instead of the U-shaped tube 151.
The raw water line 11 is connected to the first end opening 150a of the filtration membrane element set 150, and the first concentrated water line 13 is connected to the second end opening 150b on the opposite side.
The filtration membrane element set 150 can be, for example, one in which 2 to 10 filtration membrane elements 140 are connected in series.

The first filtration membrane device 2 shown in FIG. 4 is a modular filtration membrane element set 160 in which the filtration membrane element set 150 is housed in a tubular casing 161 and is formed into one tubular as a whole.
The modular filtration membrane element set 160 is housed in a cylindrical shape in which the filtration membrane element set 150 is rolled into a tubular casing 161 in which both end faces (first end face 162 and second end face 163) are closed. It is what has been done.
The raw water inlet 163 and the concentrated water outlet 164 of the filtration membrane element set 150 are projected from the first end surface 162 of the tubular casing 161.
A filtered water outlet 165 protrudes from the side surface 164 of the tubular housing 161, and a ventilation hole (not shown) is further formed.
The modular filtration membrane element set 160 can be used alone or in combination of two or more.

The first filtered water tank 3 is for storing the first filtered water obtained by filtering with the first filtration membrane device 2.
The filtered water outlet of the first filtration membrane device 2 and the first filtered water tank 3 are connected by a first filtered water line 12.

The second filtration membrane device 4 is for filtering the first filtered water of the first filtered water tank 3 to obtain the second filtered water.
The second filtration membrane device 4 preferably has a spiral RO membrane as a separation membrane, and more preferably the spiral RO membrane made of polyamide.
The first filtered water tank 3 and the raw water inlet (first filtered water inlet) of the second filter membrane device 4 are connected by a second filtered water line 14 provided with a second circulation pump 21.
A water sampling line 15 for the second filtered water is connected to the filtered water outlet of the second filtration membrane device 4, and the water sampling line 15 is connected to a second filtered water tank (not shown) as needed. May be.
The concentrated water outlet of the second filtration membrane device 4 and the first filtered water tank 3 are connected by a second concentrated water line 16.
It has a second circulation line including a first filtered water tank 3, a second filtered water line 14, a second filtration membrane device 4, a second concentrated water line 16, and a first filtered water tank 3. An on-off valve (opening / closing valve) such as a solenoid valve can be installed in each of the second circulation lines as needed.

[Operation method of the first wastewater treatment system shown in FIG. 1]
An aspect of the operation method of the wastewater treatment system will be described with reference to FIG.
First, a wastewater transmission process is carried out in which oil-impregnated wastewater generated in various factories is sent to the raw water tank 1 for storage.
The oil-impregnated wastewater stored in the raw water tank 1 can be treated with chemicals as needed, but with the wastewater treatment system shown in FIG. 1, even if no chemicals are used or the amount of chemicals used is reduced. High levels of filtration treatment can be performed to obtain reusable treated water.

Next, the first circulation pump 20 is operated, and the raw water (oil-containing wastewater) in the raw water tank 1 is sent to the first filtration membrane device 2 by the raw water line 11 and filtered to obtain the first filtered water. do.
The first concentrated water obtained in the first filtration step is returned from the first concentrated water line 13 to the raw water tank 1 and is treated as raw water again in the first filtration step.
The first filtration step described above is repeated using the first circulation line.
When the suspension concentration in the raw water becomes excessive due to the return of the first concentrated water to the raw water tank 1, a part of the raw water in the raw water tank 1 is discharged and a separately installed concentrated water tank is used. It can also store water in.

The first filtered water obtained in the first filtering step is sent to the first filtered water tank 3 by the first filtered water line 12 and stored (first filtered water storage step).
Next, the second circulation pump 21 is operated, and the first filtered water in the first filtered water tank 3 is sent to the second filtered membrane device 4 by the second filtered water line 14 to be filtered to obtain the second filtered water. The second filtration step is carried out.
Next, the second filtered water obtained in the second filtering step is sampled from the water sampling line 15, stored as necessary, and is used for industrial water, reclaimed water, washing water, fire protection water, and planting water. It can be reused as water for melting snow or sprinkling water.
The second concentrated water obtained in the second filtration step is returned from the second concentrated water line 16 to the first filtered water tank 3 and is treated again as the first filtered water in the second filtering step.
The second filtration step described above is repeated using the second circulation line.

[Second wastewater treatment system shown in FIG. 5]
The second wastewater treatment system will be described with reference to FIG.
Oil-containing wastewater is stored in the raw water tank 31. The raw water tank 31 is provided with a temperature control device (not shown), a thermometer (not shown), and a water level gauge (not shown) for adjusting the internal raw water temperature, if necessary. Can be done.

The oil-containing wastewater is wastewater containing a water-soluble oil, a surfactant and the like, and is, for example, wastewater having a COD of 6000 mg / L or more, a BOD of 5000 mg / L or more, and n-hexane of 1000 mg / L or more.
The oil-impregnated wastewater is sent from the oil-impregnated wastewater source to the raw water tank 31 by the oil-impregnated wastewater line 40 and stored. A pre-filter for removing large foreign substances such as metal pieces can be installed in the oil-impregnated wastewater line 40.
As the oil-impregnated wastewater source, the one collected in the wastewater pit (drainage tank) into which the oil-impregnated wastewater generated in various factories flows can also be used.
The wastewater pit may be connected to a discharge line at the bottom for discharging sediments such as gravel and sand, and sediments when a flocculant is added.
The type and concentration of the oil in the oil-containing wastewater are not particularly limited, and for example, the components are the same as the amount of the n-hexane extract described in JP-A-2003-93803, and the same concentration range is used as a reference. Can be done.
If necessary, one or more chemicals selected from a surfactant, a flocculant, and an adsorbent can be added to the oil-containing wastewater in the wastewater pit.

The pretreatment filtration membrane device 32 is for filtering the oil-impregnated wastewater of the raw water tank 31 to obtain pretreatment water.
The pretreatment filtration membrane device 32 has a UF membrane or an MF membrane as a separation membrane, and a tubular type UF membrane is preferable.
As the pretreatment filtration membrane device 32 including the tubular type UF membrane, the one shown in FIGS. 2 to 4 which is the same as the first filtration membrane device 2 can be used.

The raw water tank 31 and the raw water inlet of the pretreatment filtration membrane device 32 are connected by a raw water line 41 provided with a pretreatment circulation pump 50. If necessary, a pre-filter can also be installed between the raw water tank 31 and the pretreatment filtration membrane device 32.
The concentrated water outlet of the pretreatment filtration membrane device 32 and the raw water tank 31 are connected by a pretreatment concentrated water line 43.
It has a pretreatment circulation line including a raw water tank 31, a raw water line 41, a pretreatment filtration membrane device 32, a pretreatment concentrated water line 43, and a raw water tank 31. An on-off valve (opening / closing valve) such as a solenoid valve can be installed in each of the pretreatment circulation lines as needed.

The pretreatment water tank 33 is for storing the pretreatment water obtained by filtering with the pretreatment filtration membrane device 32.
The filtered water outlet of the pretreatment filtration membrane device 32 and the pretreatment water tank 33 are connected by a first pretreatment water line 42.

The first filtration membrane device 34 is for filtering the pretreated water in the pretreated water tank 33 to obtain the first filtered water.
The first filtration membrane device 34 is preferably a device including a tubular RO membrane or a tubular NF membrane as a separation membrane, and the tubular RO membrane and the tubular NF membrane are more preferably made of cellulose acetate. preferable.
As the first filtration membrane device 34 including the tubular RO membrane or the tubular NF membrane, the ones shown in FIGS. 2 to 4 can be used.

The pretreatment water tank 33 and the raw water inlet of the first filtration membrane device 34 are connected by a second pretreatment water line 44 provided with a first circulation pump 51.
The concentrated water outlet of the first filtration membrane device 34 and the pretreatment water tank 33 are connected by a first concentrated water line 46.
It has a first circulation line including a pretreatment water tank 33, a second pretreatment water line 44, a first filtration membrane device 34, a first concentrated water line 46, and a pretreatment water tank 33. An on-off valve (opening / closing valve) such as a solenoid valve can be installed in each of the first circulation lines as needed.

The first filtered water tank 35 is for storing the first filtered water obtained by filtering with the first filtration membrane device 34.
The filtered water outlet of the first filtration membrane device 34 and the first filtered water tank 35 are connected by a first a filtered water line 45.

The second filtration membrane device 36 is for filtering the first filtered water of the first filtered water tank 35 to obtain the second filtered water.
The second filtration membrane device 36 preferably has a spiral RO membrane as a separation membrane, and a membrane in which the spiral RO membrane is made of polyamide is more preferable because it has a high inhibition rate of impurities in water.
On the other hand, since the spiral type RO membrane made of polyamide causes a sharp decrease in the treatment amount especially when treating oil-containing wastewater, it is necessary to pretreat with the first filtration membrane device 34.
The raw water inlet of the first filtered water tank 35 and the second filtration membrane device 36 are connected by a first b filtered water line 46 provided with a second circulation pump 52.
A water sampling line 47 for the second filtered water is connected to the filtered water outlet of the second filtration membrane device 36, and the water sampling line 47 is connected to a second filtered water tank (not shown) as needed. May be.
The concentrated water outlet of the second filtration membrane device 36 and the first filtered water tank 35 are connected by a second concentrated water line 48.
It has a second circulation line including a first filtered water tank 35, a first b filtered water line 46, a second filtration membrane device 36, a second concentrated water line 48, and a first filtered water tank 35. An on-off valve (opening / closing valve) such as a solenoid valve can be installed in each of the second circulation lines as needed.

[Operation method of the second wastewater treatment system shown in FIG. 5]
An aspect of the operation method of the second wastewater treatment system will be described with reference to FIG.
First, a wastewater transmission process is carried out in which oil-impregnated wastewater generated in various factories is sent to a raw water tank 31 for storage.
The oil-impregnated wastewater stored in the raw water tank 31 can be treated with chemicals as needed, but with the wastewater treatment system shown in FIG. 5, even if no chemicals are used or the amount of chemicals used is reduced. High levels of filtration treatment can be performed to obtain reusable treated water.

Next, the pretreatment circulation pump 50 is operated, and the raw water (oil-containing wastewater) in the raw water tank 31 is sent to the pretreatment filtration membrane device 32 by the raw water line 41 and filtered to obtain the pretreatment water. do.
The pretreatment concentrated water obtained in the pretreatment step is returned from the pretreatment concentrated water line 43 to the raw water tank 31, and is treated again as raw water in the pretreatment step.
The above pretreatment step is repeated using the pretreatment circulation line.
When the suspension concentration in the raw water becomes excessive by returning the first concentrated water to the raw water tank 31, a part of the raw water in the raw water tank 31 is discharged and a separately installed concentrated water tank is installed. It can also store water in.

The pre-treated water obtained in the pre-treatment step is sent to the pre-treatment water tank 33 by the first pre-treatment water line 42 and stored (pre-treatment water storage step).
Next, the first circulation pump 51 is operated, and the pretreated water in the pretreated water tank 1 is sent to the first filtration membrane device 34 by the second pretreated water line 44 and filtered to obtain the first filtered water. Carry out a filtration step.
The first concentrated water obtained in the first filtration step is returned from the first concentrated water line 46 to the pretreated water tank 33, and is treated again in the first filtration step as pretreated water.
The first filtration step described above is repeated using the first circulation line.

The first filtered water obtained in the first filtration step is sent to the first filtered water tank 35 by the first a filtered water line 45 and stored (first filtered water storage step).
Next, the second circulation pump 52 is operated, and the first filtered water in the first filtered water tank 35 is sent to the second filtering membrane device 36 by the first b filtered water line 46 and filtered to obtain the second filtered water. 2 Carry out the filtration step.
Next, the second filtered water obtained in the second filtering step is sampled from the sampling line 47, stored as necessary, and is used for industrial water, reclaimed water, washing water, fire protection water, and planting water. It can be reused as water for melting snow or sprinkling water.
The second concentrated water obtained in the second filtration step is returned from the second concentrated water line 48 to the first filtered water tank 35, and is treated again as the first filtered water in the second filtering step.
The second filtration step described above is repeated using the second circulation line.

Each aspect disclosed herein can be combined with any other feature disclosed herein.
Each configuration and a combination thereof in each embodiment are examples, and the configurations can be added, omitted, replaced, and other changes as appropriate without departing from the gist of the disclosure of the present invention. The present disclosure is not limited by embodiments, but only by the claims.

Example 1
It was carried out by the wastewater treatment system shown in FIG.
The oil-containing wastewater before treatment is a mixture of cutting oil wastewater and process wastewater discharged from a machining plant (raw water in Tables 1 to 3).
However, the raw water in Tables 1 to 3 is obtained by roughly filtering wastewater with a commercially available pincushion type prefilter having a pore size of 100 um.

Next, the raw water in the raw water tank 1 was filtered by the pretreatment filtration membrane device 32.
The pretreatment filtration membrane device 32 has a hydrophilic polyolefin membrane as a separation membrane, which is suitable for treating oil-containing waste water among tubular membrane modules, and has a pore size of 20,000 fractional molecular weight TU-2020-P18A ( A fractional molecular weight of 20,000) (manufactured by Daisen Membrane Systems Co., Ltd.) was used (TB UF membrane).
The pretreatment filtration membrane device 32 was circulated for about 300 minutes at a filtration pressure of 0.3 MPa and 25 ° C. to obtain pretreated water.

Next, the pretreated water in the pretreated water tank 33 was filtered by the first filtration membrane device 34 to obtain the first filtered water.
The first filtration membrane device 34 is a tubular module of RO / NF membrane as a separation membrane (TR-70C3-P18A; made of cellulose acetate, 2,000 ppm NaCl solution blocking 70%, membrane area 1.6 m ² ) (Daisen Membrane Systems). (Manufactured by Co., Ltd.) was used (TB RO / NF membrane).
The operating conditions of the first filtration membrane device 34 were an inlet pressure of 2 MPa, a circulation flow rate of 15 L / min, a temperature of 25 ° C., a filtration rate of about 0.4 L / min, and 80 L of the first filtered water was obtained at about 200 min.

Next, the first filtered water in the first filtered water tank 35 was filtered by the second filtration membrane device 36 to obtain the second filtered water.
The second filtration membrane device 36 used a spiral element of an RO membrane made of a polyamide composite membrane (ESPA4-2520: manufactured by Hydranautics, membrane area 1.1 m ² , 500 ppm NaCl solution blocking rate 99.0%) as a separation membrane.
The operating conditions of the second filtration membrane device 36 were an inlet pressure of 0.9 MPa, a circulation flow rate of 8 L / min, and a liquid temperature of 20 to 25 ° C., and a circulation operation of 200 minutes was performed.
The presence of the first filtration membrane device 34 makes it unnecessary to replace the membrane of the second filtration membrane device 36 for a long period of time.

Comparative Example 1
It was carried out by the wastewater treatment system for comparison shown in FIG.
The waste water treatment system of FIG. 6 includes a raw water tank 61, a first circulation pump 71, a tubular type UF membrane filtration device 62, a first filtered water tank 63, a second circulation pump 72, and a spiral type RO membrane filtration device 64. Each device and each tank is connected by each line.
The comparative wastewater treatment system of FIG. 6 lacks the first circulation line including the first filtration device 34 in the wastewater treatment system of FIG. However, as the TB UF membrane of the pretreatment filtration membrane apparatus 32, one having a molecular weight cut-off of 100,000 was used.
The operating conditions were the same as the operating conditions of the pretreatment filtration membrane device 32 and the second filtration membrane device 36 of Example 1.
Immediately after the operation, the processing amount of the second filtration membrane device 36 decreased, and after about 3 hours, the processing amount became zero, so the operation was stopped.

Comparative Example 2
It was carried out by the wastewater treatment system for comparison shown in FIG.
The same procedure as in Comparative Example 1 was carried out except that a TB UF membrane having a molecular weight cut-off of 100,000 was used as the TB UF membrane of the pretreatment filtration membrane apparatus 32.
Similar to Comparative Example 1, the processing amount of the second filtration membrane device 36 decreased immediately after the operation.

As is clear from the comparison between Tables 1 to 3, if the wastewater treatment system of the present disclosure is used, even if the wastewater is heavily soiled with oil, industrial water, reclaimed water, cleaning water, fire protection water, and planting water can be used. It could be treated to a level where it could be reused as water for melting snow or sprinkling water.

The wastewater treatment system and its operation method of the present disclosure can be used for treating wastewater containing oil generated in various factories, business establishments, etc., for example, a die containing an oil-containing wastewater containing a mold release agent applied to a mold. It can treat cast wastewater, car wash wastewater, wastewater from large-scale cooking facilities, etc.

1,31 Raw water tank 2,34 1st filter membrane device 3,35 1st filter water tank 4,36 2nd filter membrane device 32 Pretreatment filter membrane device 33 Pretreatment water tank

Claims (6)

The raw water tank (1) in which the oil-impregnated waste water is stored, the first filter membrane device (2) that filters the oil-containing waste water in the raw water tank (1) to obtain the first filtered water, and the first filtration that stores the first filtered water. An oil-containing wastewater treatment system equipped with a second filter membrane device (4) that filters the first filtered water of the water tank (3) and the first filtered water tank (3) to obtain the second filtered water.
The first filtration membrane device (2) has a separation membrane selected from a tubular RO membrane and a tubular NF membrane, and the second filtration membrane device (4) has a spiral RO membrane.
The separation membrane selected from the tubular RO membrane and the tubular NF membrane of the first filtration membrane device (2) is made of cellulose acetate.
The spiral RO membrane of the second filtration membrane device (4) is made of polyamide.
The raw water tank (1) and the first filtration membrane device (2) are connected by a raw water line (11) equipped with a first circulation pump (20).
The first filtration membrane device (2) and the first filtered water tank (3) are connected by the first a filtered water line (12).
The first filtration membrane device (2) and the raw water tank (1) are connected by the first concentrated water line (13).
It has a first circulation line consisting of a raw water tank (1), a raw water line (11), a first filtration membrane device (2), a first concentrated water line (13) and a raw water tank (1).
The first filtered water tank (3) and the second filtration membrane device (4) are connected by a first b filtered water line (14) equipped with a second circulation pump (21).
The second filtration water sampling line (15) is connected to the second filtration membrane device (4), and the second filtration water sampling line (15) is connected.
The second filtration membrane device (4) and the first filtered water tank (3) are connected by the second concentrated water line (16).
A second circulation line consisting of a first filtered water tank (3), a first b filtered water line (14), a second filtering membrane device (4), a second concentrated water line (16) and a first filtered water tank (3). Has an oil-impregnated wastewater treatment system. Raw water tank (31) in which oil-impregnated waste water is stored, pretreatment filter membrane device (32) that filters oil-impregnated waste water in raw water tank (31) to obtain pretreatment water, and pretreatment water tank that stores the pretreatment water. (33), a first filter membrane device (34) that filters the pretreated water of the pretreated water tank (33) to obtain the first filtered water, and a first filtered water tank (35) that stores the first filtered water. , An oil-impregnated waste water treatment system equipped with a second filter membrane device (36) for filtering the first filtered water of the first filtered water tank (35) to obtain the second filtered water.
The pretreatment filtration membrane device (32) has a UF membrane or an MF membrane, and the first filtration membrane device (34) has a separation membrane selected from a tubular RO membrane and a tubular NF membrane, and a second. The filtration membrane device (36) has a spiral RO membrane,
The raw water tank (31) and the pretreatment filtration membrane device (32) are connected by a raw water line (41) equipped with a pretreatment circulation pump (50).
The pretreatment filtration membrane device (32) and the pretreatment water tank (33) are connected by the first pretreatment water line (42).
The pretreatment filtration membrane device (32) and the raw water tank (31) are connected by the pretreatment concentrated water line (43).
It has a pretreatment circulation line consisting of a raw water tank (31), a raw water line (41), a pretreatment filtration membrane device (32), a pretreatment concentrated water line (43) and a raw water tank (31).
The pretreatment water tank (33) and the first filtration membrane device (34) are connected by a second pretreatment water line (44) equipped with a first circulation pump (51).
The first filtration membrane device (34) and the first filtered water tank (35) are connected by the first a filtered water line (45).
The first filtration membrane device (34) and the pretreatment water tank (33) are connected by the first concentrated water line (46).
A first circulation line consisting of a pretreatment water tank (33), a second pretreatment water line (44), a first filtration membrane device (34), a first concentrated water line (46) and a pretreatment water tank (33). Have and
The first filtered water tank (35) and the second filtration membrane device (36) are connected by a first b filtered water line (46) equipped with a second circulation pump (52).
The second filtration water sampling line (47) is connected to the second filtration membrane device (36), and the second filtration water sampling line (47) is connected.
The second filtration membrane device (36) and the first filtered water tank (35) are connected by the second concentrated water line (48).
A second circulation line consisting of a first filtered water tank (35), a first b filtered water line (46), a second filtering membrane device (36), a second concentrated water line (48) and a first filtered water tank (35). Has an oil-impregnated wastewater treatment system. The pretreatment filtration membrane device (32) has a tubular type UF membrane.
The separation membrane selected from the tubular RO membrane and the tubular NF membrane of the first filtration membrane device (2) is made of cellulose acetate.
The oil-impregnated wastewater treatment system according to claim 2 , wherein the spiral RO membrane of the second filtration membrane apparatus (4) is made of polyamide. The method of operating the wastewater treatment system according to claim 1 .
Using the first circulation line,
Wastewater transmission process, in which oil-impregnated wastewater is sent to the raw water tank (1) and stored.
The first filtration step of operating the first circulation pump (20), sending the raw water in the raw water tank (1) to the first filtration membrane device (2) by the raw water line (11), and filtering the raw water to obtain the first filtered water. ,
A water storage step of the first filtered water, in which the first filtered water obtained in the first filtering step is sent to the first filtered water tank (3) by the first a filtered water line (12) and stored.
A step of returning the concentrated water obtained in the first filtration step to the raw water tank (1) by the first concentrated water line (13) was carried out.
Using the second circulation line,
The second circulation pump (21) is operated, and the first filtered water in the first filtered water tank (3) is sent to the second filter membrane device (4) by the first b filtered water line (14) to be filtered. 2 Second filtration step to obtain filtered water,
A water sampling step of collecting the second filtered water obtained in the second filtering step,
An operating method of an oil-containing wastewater treatment system, which carries out a step of returning the concentrated water obtained in the second filtering step to the first filtered water tank (3) by the second concentrated water line (16). The method of operating the wastewater treatment system according to claim 2 or 3 .
Using the pretreatment circulation line,
Wastewater transmission process, which sends oil-impregnated wastewater to the raw water tank (31) and stores it.
Pretreatment filtration step in which the pretreatment circulation pump (50) is operated and the raw water in the raw water tank ( 31 ) is sent to the pretreatment filtration membrane device (32) by the raw water line (41) to obtain the pretreatment water.
The pretreatment water storage step, in which the pretreatment water obtained in the pretreatment filtration step is sent to the pretreatment water tank (33) by the first pretreatment water line (42) and stored.
A step of returning the concentrated water obtained in the pretreatment filtration step to the raw water tank (31) by the pretreatment concentrated water line (43) was carried out.
Using the first circulation line,
The first circulation pump (51) is operated, and the pretreated water in the pretreated water tank (33) is sent to the first filter membrane device (34) by the second pretreated water line (44) to be filtered. 1 First filtration step to obtain filtered water,
A water storage step of the first filtered water, in which the first filtered water obtained in the first filtering step is sent to the first filtered water tank (35) by the first a filtered water line (45) and stored.
A step of returning the first concentrated water obtained in the first filtration step to the pretreatment water tank (33) by the first concentrated water line (46) was carried out.
Using the second circulation line,
The second circulation pump (52) is operated, and the first filtered water in the first filtered water tank (35) is sent to the second filter membrane device (36) by the first b filtered water line (46) to be filtered. 2 Second filtration step to obtain filtered water,
A water sampling step of collecting the second filtered water obtained in the second filtering step,
A method for operating an oil-containing wastewater treatment system, which carries out a step of returning the second concentrated water obtained in the second filtering step to the first filtered water tank (35) by the second concentrated water line (48). The oil-containing wastewater is wastewater containing a water-soluble oil and a surfactant, and has a COD of 6000 mg / L or more, a BOD of 5000 mg / L or more, and n-hexane of 1000 mg / L or more, claim 4 or 5 . The operation method of the oil-impregnated wastewater treatment system described.

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