JP5818670B2 - Oil-containing wastewater treatment equipment - Google Patents

Description

  Embodiments of the present invention relate to an oil-containing wastewater treatment apparatus and a wastewater treatment method for removing oil and suspended particles (SS) present in water.

  In recent years, effective use of water resources is required due to industrial development and population growth. For this purpose, it is very important to reuse industrial wastewater and other wastewater. In order to achieve these, it is necessary to purify the water, ie to separate other substances from the water.

  Various methods are known as methods for separating other substances from the liquid, such as membrane separation, centrifugation, activated carbon adsorption, ozone treatment, aggregation, and removal of suspended substances with a predetermined adsorbent. It is done. By such a method, chemical substances having a great influence on the environment such as phosphorus and nitrogen contained in water can be removed, and oils and clays dispersed in water can be removed.

  Among these, membrane separation is one of the most commonly used methods. However, when removing oils and minute SS dispersed in water, the pores of the membrane are likely to be clogged. There is a problem that the life is likely to be shortened. For this reason, in order to remove oil and fine suspended matters in water, filtration treatment is not appropriate or a large amount of flocculant is often added.

  On the other hand, as a method for removing oil from water, there is known a method in which pressure levitation separation is performed by adding a flocculant and a polymer flocculant to a substance that dissolves in water. As an example of this method, for example, an oil adsorbent composed of a powdered organic polymer is added to raw water to adsorb oil, and this mixed water is introduced into a rapid stirring tank to add a flocculant to agglomerate and loosen. A technique is disclosed in which a polymer flocculant is added by introduction into a fast stirring tank, and the mixture is slowly stirred to form a floc for pressure floating separation.

JP-A-7-96284

  In the above technique, the particle size is increased by using a polymer flocculant polymer in addition to the flocculant for the oil in water. However, since an inorganic flocculant is used in a large amount, there is a problem that the chemical cost is increased, and there is a problem that the amount of sludge is increased when the company is out of business. If these can be separated into solid and liquid by direct filtration or the like, the amount of chemicals used and sludge generation will be reduced, but direct filtration is difficult because the particle diameter is fine and the filter is frequently clogged.

  An object of the embodiment is to provide an oil-containing wastewater treatment apparatus and a wastewater treatment method capable of treating oil-containing wastewater with a small amount of chemical use.

  According to the embodiment, a coagulation tank for supplying a polymer flocculant to water to be treated containing suspended particles and oil, and a coprecipitation containing a magnetic substance and storing a coprecipitate having a primary particle diameter of 5 to 100 μm. A precipitant reservoir, a settling tank that separates water to be treated into primary treated water and a coprecipitate slurry by a coprecipitate sent from the coprecipitate reservoir, and a coprecipitate slurry that has been settled and separated in the settling tank. The coprecipitation agent washing tank which is separated and separated into the coprecipitation agent and the suspended particles by a magnet and washed, and the coprecipitation agent slurry settled and separated in the precipitation tank is transferred to the coprecipitation agent washing tank. A first return mechanism, a second return mechanism for returning the washed coprecipitate to the coprecipitate storage tank, and a filter aid containing a magnetic substance and having a primary particle diameter of 0.5 to 50 μm are supplied. Filter aid storage tank, raw filter tank for temporarily storing primary treated water, and filter aid A mixing tank for preparing a filter aid slurry by mixing the next treated water, a solid-liquid separator for filtering the filter aid slurry and the primary treated water, and removing the filter aid deposited from the solid-liquid separator. A cleaning mechanism, a filter aid washing tank for separating the filter aid and suspended particles, and a third return mechanism for returning the filter aid separated in the filter aid washing tank to the filter aid storage tank. It is possible to provide an oil-containing wastewater treatment apparatus characterized by comprising.

Explanatory drawing of the oil-containing wastewater treatment apparatus which concerns on 1st Embodiment. Explanatory drawing of the oil-containing wastewater treatment apparatus which concerns on 5th Embodiment.

Next, the oil-containing wastewater treatment apparatus and treatment method according to the present embodiment will be described in detail.
The coprecipitation agent according to the present embodiment contains a magnetic substance and has a primary particle diameter of 5 to 100 μm. The coprecipitate may be aggregated as described later. Further, it may be a magnetic substance alone, or may be coated or aggregated with a polymer or the like. Here, the average particle diameter is measured by a laser diffraction method. Specifically, it can be measured by a SALD-DS21 type measuring device (trade name) manufactured by Shimadzu Corporation. If the average particle size of the magnetic substance as particles is larger than 100 μm, the sedimentation speed of the coprecipitation agent itself is so fast that it may not aggregate with the fine precipitates in water described later. On the other hand, when the average particle size is smaller than 5 μm, the particles are densely aggregated and fine precipitates in water can be removed, but separation and recovery / reuse may not be possible. By incorporating these magnetic materials, the specific gravity of the coprecipitate becomes relatively high, so it is possible to use sedimentation by gravity and separation by centrifugal force using a cyclone in combination with magnetic separation. The coprecipitate can be quickly separated from the water.

  As the filter aid according to the present embodiment, those containing particles containing a magnetic substance and having a primary particle diameter of 0.5 to 50 μm are used. The particles may be a magnetic substance alone, or may be coated or aggregated with a polymer or the like. More preferably, the size A of the magnetic material is A = 0.5 to 5 μm, the magnetic material is partially aggregated by a polymer or trialkoxysilane, and the diameter B of the aggregate is A <B ≦ 50 μm. The surface coating thickness C of the polymer is preferably 0.01 ≦ C ≦ 0.25 μm.

  Here, the primary particle diameter is measured by a laser diffraction method. Specifically, it can be measured by a SALD-DS21 type measuring device (trade name) manufactured by Shimadzu Corporation. When the primary particle diameter is larger than 50 μm, the distance between the particles becomes too large, and fine precipitates in water described later may pass therethrough. Further, when the primary particle diameter is smaller than 0.5 μm, the particles are densely aggregated and fine precipitates in the water can be removed, but an effective water flow rate may not be obtained. By incorporating these magnetic materials, the specific gravity of the filter aid is relatively high, so it is possible to use sedimentation by gravity and separation by centrifugal force using a cyclone in combination with magnetic separation. Filter aid can be quickly separated from water.

Ferromagnetic materials can be generally used as the magnetic material. For example, iron and alloys containing iron, magnetite, titanite, pyrrhotite, magnesia ferrite, cobalt ferrite, nickel ferrite, barium ferrite, etc. Compounds. If it is a ferrite compound excellent in stability in water among these, the effect by this embodiment can be achieved more effectively. For example, magnetite (Fe ₃ O ₄ ), which is a magnetite, is preferable because it is not only inexpensive, but also stable as a magnetic substance in water and safe as an element, so that it can be easily used for water treatment. The magnetic body can take various shapes such as a spherical shape, a polyhedron, and an indeterminate shape, but is not particularly limited. The particle size and shape of the magnetic carrier that is desirable for use may be selected as appropriate in consideration of production costs and the like, and a spherical or round polyhedral structure is particularly preferable. These magnetic materials may be subjected to normal plating treatment such as Cu plating and Ni plating if necessary.

  In addition, in an aggregate composed of secondary aggregates in which magnetic bodies whose surfaces are coated with a polymer are aggregated, primary particles of a core / shell structure in which a magnetic body is a core and a polymer layer covering the surface forms a shell. Aggregates to form secondary aggregates.

  In this embodiment, the polymer used for covering and aggregating the surface of the magnetic material can be selected according to the purpose. Preferably, polyacrylonitrile, polymethyl methacrylate, polystyrene and their copolymers, which are easy to coat on magnetic materials and have acid resistance and alkali resistance, phenol resins excellent in dispersion in water, and firmly adhere to magnetic materials in water. A trialkoxysilane condensate having high stability is preferably used. The average surface coating thickness C of this polymer is preferably coated so that 0.01 ≦ C ≦ 0.25 μm.

  Here, when thickness C is thinner than 0.01 micrometer, the intensity | strength of a secondary aggregate will become weak and it may be difficult to use it in water. Moreover, when thickness C is thicker than 0.25 micrometer, the space | gap between particle | grains becomes narrow and when it uses as a filter aid, an effective water flow amount may not be ensured. Calculation of the polymer coating amount may be measured by observation with an optical microscope or SEM. Preferably, the polymer coating amount is raised to a high temperature in an oxygen-free state, and the filter aid is thermally decomposed to obtain the weight loss amount, that is, the polymer coating amount. The average thickness of the polymer layer can be accurately calculated from the specific surface area of the particles.

  The filter aid according to the present embodiment can be produced by any method as long as it can realize the structure of the filter aid. As an example of such a method, a polymer is dissolved in an organic solvent capable of dissolving the polymer, a composition in which a magnetic material is dispersed in the solution is prepared, and the organic solvent is removed by spraying the composition. A spray drying method is mentioned. According to this method, it is possible to adjust the average particle size of the secondary aggregates in which the primary particles are aggregated by adjusting the environmental temperature of the spray drying, the ejection speed, etc., and the organic solvent is removed from between the aggregated primary particles. In this case, pores are formed, and a suitable porous structure can be easily formed.

  On the other hand, industrially, a polymer solution was prepared by dissolving a polymer in a solvent capable of dissolving the polymer, and the polymer solution was poured onto the surface of a magnetic body placed in a mold, and the solvent was removed and solidified. The filter aid can also be formed by crushing a product or by crushing a solid obtained by removing an organic solvent from a composition in which a magnetic material is dispersed in a polymer solution. Moreover, a filter aid can be manufactured by dripping the composition which melt | dissolved the polymer in the solvent to a Henschel mixer, a ball mill, or a granulator, and making it dry. At this time, a preferred filter aid can be produced through two steps of production conditions for covering the surface of the magnetic material and conditions for aggregating the magnetic material.

  In the oil-containing wastewater treatment method according to this embodiment, a polymer flocculant is added as a flocculant to water to be treated containing oil to form primary floc. The type of the polymer flocculant is not particularly limited, but a cationic polymer is the best. Flocks formed by the polymer flocculant treatment for such oil-containing wastewater have a slow sedimentation rate and are difficult to settle. However, when the method according to the present embodiment is used, the precipitation process can be easily performed due to the effect of the coprecipitation agent, and thus the apparatus is easily simplified. For SS containing oil in a fine particle system that cannot be treated by precipitation treatment, it can be filtered by adding a filter aid containing a magnetic substance and primary particles of 0.5 to 50 μm. .

The oil-containing wastewater treatment apparatus according to this embodiment includes the following two types.
(First oil-containing wastewater treatment device)
The first oil-containing wastewater treatment apparatus is an apparatus using a so-called precoat method, and is particularly effective when the SS concentration containing the oil remaining in the water to be treated is low.
First, a filter aid containing a magnetic substance and a dispersion medium are mixed to prepare a suspension. The filter aid containing a magnetic material can be configured as described above. As the dispersion medium, water is mainly used, but other dispersion mediums can be appropriately used. The concentration of the filter aid in the suspension is not particularly limited as long as a precoat layer can be formed by the following operation, but is adjusted to, for example, about 10,000 to 200,000 mg / L.

  Next, the suspension is passed through a filter, the filter aid in the suspension is filtered and left on the filter to form a filter layer in which the filter aid is laminated, that is, the precoat layer. In addition, water flow is performed under pressure.

  Further, since the precoat layer is formed and held by the action of external force as described above, the filtering operation (filtering) is performed, for example, by placing the filter so as to close the container opening of a predetermined container, and thus The filter aid remains on the arranged filter so that it is arranged and laminated. In this case, the precoat layer is formed and held by the external force from the wall surface of the container and the downward external force (gravity) due to the weight of the filter aid positioned above. In addition, although the thickness of a precoat layer changes with the density | concentrations of the liquid to process, it is about 0.1-10 mm in general.

  Next, the water to be treated is passed through the precoat layer formed as described above to remove SS containing oil. Water flow is mainly performed under pressure. At this time, SS containing oil in the water to be treated is removed by adsorbing to the surface of the precoat layer, specifically, the filter aid constituting the precoat layer. At this time, by setting the filter aid to a special configuration as described above, it is possible to trap the SS containing the oil and obtain a sufficient water flow rate.

  After removing the SS in water, the precoat layer is dispersed in the dispersion medium, the precoat layer is decomposed into a filter aid, and the filter aid is washed. This cleaning may be performed in a container in which a filter is installed or in another container. When using other containers, the precoat layer is decomposed into filter aids by means such as washing, and then transported. Although water is used for washing, washing with a surfactant or an organic solvent is also possible.

  Next, the washed filter aid is recovered using magnetic separation. The method of magnetic separation is not particularly limited, but there are a method of collecting permanent magnets or electromagnets in a container and recovering, a method of recovering particles by opening a magnetic field by recovering with a metal mesh magnetized by a magnet, etc. Can be mentioned.

  In the first oil-containing wastewater treatment apparatus, a precoat layer is formed on the filter in advance, and then the wastewater is passed through. Therefore, SS containing the oil adsorbed on the surface of the filter aid along with the treatment time. The amount of increases. As a result, particularly excessively adsorbed SS embeds the pores of the filter aid, so that the water flow rate is reduced. Therefore, as described above, the first fat-containing wastewater treatment apparatus is effective when the SS concentration in water is low.

(Second oil-containing wastewater treatment equipment)
The second oil-containing wastewater treatment apparatus is a so-called body feed method, and is effective when the SS concentration remaining in the water to be treated is high as described below.
Also in this oil-containing wastewater treatment apparatus, first, a filter aid and a dispersion medium are mixed to prepare a suspension. The dispersion medium used in this case is treated water. That is, in this apparatus, the filter aid is directly introduced into the waste water to adjust the suspension from the waste water. The concentration of the filter aid in the suspension is not particularly limited as long as a filtration layer can be formed by the following operation, but is adjusted to, for example, about 10,000 to 200,000 mg / L.

Next, the suspension (water to be treated) is passed through a filter, and the filter aid in the suspension is filtered and left on the filter to form a filter layer formed by aggregation of the filter aid. In addition, water flow is performed under pressure.
Further, since the filtration layer is formed and held by the action of an external force as described above, filtering is performed, for example, by placing the filter so as to close the container opening of a predetermined container, and on the filter thus arranged. So that the filter aid remains and is arranged and laminated. In this case, the filtration layer is formed and held by an external force (gravity) downward due to the external force from the wall surface of the container and the weight of the filter aid positioned above.

  After removing SS containing oil in the waste water as described above, the filter layer is dispersed in the dispersion medium, the filter layer is decomposed into a filter aid, and the filter aid is washed. This cleaning may be performed in a container in which a filter is installed or in another container. When using other containers, the filter layer is decomposed into filter aids using means such as washing, and then transported. Although water is used for washing, washing with a surfactant or an organic solvent is also possible.

  Next, the washed filter aid is recovered using magnetic separation. The method of magnetic separation is not particularly limited, but there are a method of collecting permanent magnets or electromagnets in a container and recovering, a method of recovering particles by opening a magnetic field by recovering with a metal mesh magnetized by a magnet, etc. Can be mentioned.

  In the second oil-containing wastewater treatment apparatus, the filter aid constituting the filter layer is contained in the water to be treated, that is, the suspension prepared using this water, so the oil to be removed The primary agglomerates are always supplied together with the water to be treated (suspension) containing SS containing the.

  Therefore, even when the amount of SS containing oil in the water to be treated (suspension) is large, the supply of SS and the supply of filter aid are performed simultaneously, so the first oil-containing wastewater Like a processing apparatus, SS which adsorb | sucked excessively does not embed the space | gap of a filter aid. For this reason, the filtration rate can be maintained for a long time. As a result, as described above, the second oil-containing wastewater treatment apparatus is effective when the SS concentration containing the oil in the wastewater is high.

Next, specific embodiments will be described in detail.
(Preparation of coprecipitate)
(Coprecipitant A)
Ferrite particles having an average particle diameter of 5 μm were prepared.
(Coprecipitant B)
Ferrite particles having an average particle diameter of 20 μm were prepared.
(Coprecipitant C)
Ferrite particles having an average particle size of 80 μm were prepared.
(Preparation of filter aid)
(Filter aid A)
Magnetite particles having an average particle diameter of 2 μm were prepared.
(Filter aid B)
Magnetite particles having an average particle size of 0.5 μm were prepared.

(First embodiment)
Please refer to FIG.
First, water to be treated containing oil and SS is supplied to the coagulation tank 1, and an aqueous cation polymer solution as a polymer coagulant is added to the coagulation tank 1 to form floc. The agglomeration tank 1 includes a variable speed stirrer (not shown) so that the agitation in the agglomeration tank 1 can be controlled. The water to be treated containing fine floc is sent to the precipitation tank 2. The coprecipitation agent is sent from the coprecipitation agent storage tank 3 to the precipitation tank 2, and is mixed with fine flocs and settled. In the sedimentation tank 2, SS having a high sedimentation speed is separated. The mixture of precipitated SS and coprecipitate is withdrawn and transferred to the coprecipitate washing tank 4. Here, the 1st return mechanism is comprised by the piping 5a which connects the sedimentation tank 2 and the coprecipitation agent washing tank 4, and the pump 6a interposed by this piping 5a.

  The coprecipitate washing tank 4 includes a stirring mechanism and a magnet 7, separates the coprecipitate and SS while mixing, and collects and separates only the coprecipitate with the magnet 7. The liquid from which the coprecipitate is recovered is returned to the coprecipitate storage tank 3 as a slurry (concentrated drainage) containing a high concentration coprecipitate. The coprecipitate returned in this way is supplied again to the precipitation tank 2 and reused. Here, a second return mechanism is constituted by a pipe 5b connecting the coprecipitate washing tank 4 and the coprecipitate storage tank 3 and a pump 6b interposed in the pipe 5b.

  The treated water (primary treated water) separated from the SS having a high sedimentation speed in the sedimentation tank 2 is transferred to the raw filtration tank 8. In the mixing tank 9, a filter aid slurry is made by mixing the filter aid with treated water that is partially reused. The treated water can be tap water. The filter aid slurry is sent to the solid-liquid separator 10 in which the filter 11 is first provided horizontally, and a filter aid film is formed on the filter 11. The raw filtration tank 8 and the solid-liquid separator 10 are connected by a pipe 5c with a pump 6c interposed. Here, a cleaning mechanism is configured by the cleaning liquid supplied to the solid-liquid separator 10 and the pipe 5e through which the slurry separated from the filter 11 by the cleaning liquid is supplied to the filter aid cleaning tank 13.

  Then, the to-be-processed liquid containing fine SS is supplied to the solid-liquid separation apparatus 10 from the raw filter water tank 8 under pressure, and solid-liquid separation (filtration) is performed with the membrane of the filter aid formed previously. The filtrate is a treatment liquid from which fine SS has been removed and may be drained, but it can also be used as washing water for the solid-liquid separator 10 or a liquid for preparing a filter aid slurry for the mixing tank 9. When filtration of the water to be treated is completed, the SS cake separated from the filter aid exists in the filter 11 in the solid-liquid separator 10. In order to clean this, washing water is supplied from the side of the filter 11 to break the cake, and the cake is supplied to a filter aid washing tank 13 equipped with a stirrer (not shown) and a magnet 14. Further, the filter aid is supplied from the filter aid storage tank 12 filled with the filter aid A to the mixing tank 9 and mixed with partially reused treated water (primary treated water), and the filter aid slurry is mixed. Produced. This was supplied to the solid-liquid separator 10 to produce a filter aid layer having an average thickness of 1 mm on the filter 11. Here, a third return mechanism is constituted by a pipe 5d connecting the filter aid washing tank 13 and the filter aid storage tank 12, and a pump 6d interposed in the pipe 5d.

Thereafter, primary treated water was supplied from the raw filtration water tank 8 to the solid-liquid separator 10 and filtered, and it was confirmed that 99% or more of SS in the filtered water (treated water) was removed. . After the filtration treatment, washing water was supplied from the side of the filter 11 of the solid-liquid separator 10, and the layer formed on the filter 11 was broken and supplied to the filter aid washing tank 13. After operating the stirrer in the filter aid washing tank 13 to separate the filter aid and SS, the magnet 14 was operated to separate only the filter aid, and the liquid was discharged to obtain an SS concentrate. Thereafter, the magnetic field of the magnet 14 was released, cleaning water was supplied to make a filter aid slurry, and then returned to the filter aid storage tank 12. Thereafter, the mixture tank 9 was supplied to perform the same operation, but could be reused without any problem (second embodiment).
A test was performed in the same manner as in the first embodiment, except that the same apparatus as in the first embodiment was used, and the coprecipitate B was used instead of the coprecipitate A. The removal rate of SS was 99% or more. According to the second embodiment, the water flow rate of the solid-liquid separator is almost doubled as compared with the first embodiment, but the operation was possible without any problems.

(Third embodiment)
A test was performed in the same manner as in the first embodiment, except that the same apparatus as in the first embodiment was used and the coprecipitate C was used instead of the coprecipitate A. The removal rate of SS was 99% or more. According to the third embodiment, the water flow rate of the solid-liquid separation device is almost double or more compared to the first embodiment, but it was able to operate without problems.

(Fourth embodiment)
Using the same apparatus as in the first embodiment, a test was performed in the same manner except that coprecipitate B was used instead of coprecipitate A and filter aid B was used instead of filter aid A. The removal rate of SS was about 99.5%. According to the fourth embodiment, the water flow rate of the solid-liquid separator is 1.1 times that of the first embodiment, but the operation was possible without any problems.

(Fifth embodiment)
This will be described with reference to FIG. However, the same members as those in FIG. The fifth embodiment is characterized in that the raw filtration water tank 8 also has the function of the mixing tank as compared with the first embodiment.
First, water to be treated containing oil and SS is supplied to the coagulation tank 1, and an aqueous cation polymer solution as a polymer coagulant is added to the coagulation tank 1 to form floc. Water to be treated containing fine floc is sent to the precipitation tank 2. In the sedimentation tank 2, the coprecipitation agent is sent from the coprecipitation agent storage tank 3, mixed with fine flocs, and settled. In the sedimentation tank 2, SS having a high sedimentation speed is separated. The mixture of precipitated SS and co-precipitating agent is withdrawn and transferred to the co-precipitating agent washing tank 4. In the coprecipitate washing tank 4, the coprecipitate and SS are separated while mixing, and only the coprecipitate is collected and separated by the magnet 7.

  The liquid from which the coprecipitate is recovered is returned to the coprecipitate storage tank 3 as a concentrated waste water as a slurry containing a high concentration coprecipitate. The coprecipitate returned in this way is supplied again to the precipitation tank 2 and reused. The treated water separated from the SS having a high sedimentation speed in the sedimentation tank 2 is transferred to the raw filter tank 8. Further, the filter aid is also supplied from the filter aid storage tank 1 to the raw filter water tank 8, and a mixed liquid of SS-containing wastewater and filter aid is produced. This mixed liquid is sent to the solid-liquid separator 10, and SS is removed while forming a filter aid film on the filter 11. The filtrate may be drained through a neutralization tank, but can also be used as washing water for the solid-liquid separation device 10 or magnet for the separation tank.

When filtration of the water to be treated is completed, a filter aid and SS cake are present in the filter 11 in the solid-liquid separator 10. In order to wash this, the washing water is supplied from the side of the filter 11 to break the cake, and is supplied to the filter aid washing tank 13. In the filter aid washing tank 13, the filter aid and SS are separated while being mixed by the stirring mechanism, and only the filter aid is collected and separated by the magnet 14. The liquid recovered from the filter aid is washed with the supplied wash water and returned to the filter aid storage tank 12. The filter aid returned in this way is supplied again to the raw filter water tank 8 and reused.

  By the way, an aqueous solution containing 100 mg / L in terms of SS was prepared as water to be treated. Moreover, the filter aid was supplied from the filter aid storage tank 12 filled with the filter aid A to the raw filter water tank 8 at 1000 mg / L to prepare a mixed solution of the filter aid and SS-containing waste water. When this was supplied to the solid-liquid separator 10 and filtered on the filter 11, it was confirmed that 99% or more of SS in the filtered water (treated water) was removed.

  After the filtration treatment, washing water was supplied from the side of the filter 11 of the solid-liquid separator 10, and the layer formed on the filter 11 was broken and supplied to the filter aid washing tank 13. After operating the stirrer in the filter aid washing tank 13 to separate the filter aid and SS, the magnet 14 was operated to separate only the filter aid, and the liquid was discharged to obtain an SS concentrate. Thereafter, the magnetic field of the magnet 14 was released, cleaning water was supplied to make a filter aid slurry, and then returned to the filter aid storage tank 12. Thereafter, the same operation was performed by supplying the raw water to the filtration raw water tank 8, but it could be reused without any problem.

(Sixth embodiment)
A test was performed in the same manner as in the fifth embodiment, except that the same apparatus as in the fifth embodiment was used, and filter aid B was used instead of filter aid A. As a result, the copper recovery rate was 98%. In addition, according to the sixth embodiment, the water flow rate of the solid-liquid separator was 1.3 times that of the fifth embodiment, but the operation was possible without any problem.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Coagulation tank, 2 ... Precipitation tank, 3 ... Coprecipitation agent storage tank, 4 ... Coprecipitation agent washing tank, 5a-5e ... Piping, 6a-6d ... Pump, 7,14 ... Magnet, 8 ... Filtration raw water tank, DESCRIPTION OF SYMBOLS 9 ... Mixing tank, 10 ... Solid-liquid separator, 11 ... Filter, 12 ... Filter aid storage tank, 13 ... Filter aid washing tank.

Claims (4)

A coagulation tank for supplying a polymer coagulant to the water to be treated containing suspended particles and oil;
A coprecipitation agent storage tank containing a magnetic substance and storing a coprecipitation agent having a primary particle diameter of 5 to 100 μm;
A settling tank that separates water to be treated into primary treated water and coprecipitate slurry by a coprecipitate sent from the coprecipitate storage tank;
A coprecipitation agent washing tank in which the coprecipitate slurry separated and separated in the precipitation tank is transferred, and the coprecipitation slurry is separated into a coprecipitation agent and suspended particles by a magnet and washed;
A first return mechanism for transferring the coprecipitate slurry precipitated and separated in the settling tank to the coprecipitate washing tank;
A second return mechanism for returning the washed coprecipitate to the coprecipitate reservoir;
A filter aid reservoir containing a magnetic substance and supplying a filter aid having a primary particle size of 0.5 to 50 μm;
A raw filtration tank for temporarily storing primary treated water;
A mixing tank for mixing a filter aid and primary treated water to produce a filter aid slurry;
A solid-liquid separator for filtering the filter aid slurry and the primary treated water;
A cleaning mechanism for removing the filter aid deposited from the solid-liquid separator;
A filter aid washing tank for separating the filter aid and suspended particles;
An oil-containing wastewater treatment apparatus comprising a third return mechanism for returning the filter aid separated in the filter aid washing tank to the filter aid storage tank. A coagulation tank for supplying a polymer coagulant to the water to be treated containing suspended particles and oil;
A coprecipitation agent storage tank containing a magnetic substance and storing a coprecipitation agent having a primary particle diameter of 5 to 100 μm;
A settling tank that separates water to be treated into primary treated water and coprecipitate slurry by a coprecipitate sent from the coprecipitate storage tank;
A coprecipitate slurry that is separated and washed into a coprecipitate and concentrated suspended particles by means of a magnet;
A first return mechanism for transferring the coprecipitate slurry precipitated and separated in the settling tank to the coprecipitate washing tank;
A second return mechanism for returning the washed coprecipitate to the coprecipitate reservoir;
A filter aid reservoir containing a magnetic substance and supplying a filter aid having a primary particle size of 0.5 to 50 μm;
A raw filtration tank for temporarily storing primary treated water and filter aid;
A solid-liquid separator for filtering the filter aid slurry and the primary treated water;
A cleaning mechanism for removing the filter aid deposited from the solid-liquid separator;
A filter aid washing tank for separating the filter aid and suspended particles;
An oil-containing wastewater treatment apparatus comprising a third return mechanism for returning the filter aid separated in the filter aid washing tank to the filter aid storage tank. A first step of reacting water to be treated containing suspended particles and oil with a polymer flocculant;
A second step of supplying a coprecipitation agent containing a magnetic substance and having a primary particle diameter of 5 to 100 μm to the precipitation tank;
A third step of separating the treated water into suspended particles and primary treated water by gravity sedimentation;
A fourth step of transferring the slurry containing the suspended particles and the coprecipitate precipitated in the settling tank to a coprecipitate washing device;
A fifth step of separating and washing the slurry into a coprecipitate and suspended particles with a magnet;
A sixth step of supplying a filter aid containing a magnetic substance and having a primary particle size of 0.5 to 50 μm to the filter aid washing tank;
A seventh step of mixing the filter aid and primary treated water to produce a filter aid slurry;
An eighth step of supplying the filter aid slurry to a solid-liquid separator;
A ninth step of removing the filter aid deposited from the solid-liquid separator;
A tenth step of separating the filter aid and suspended particles;
An oil-containing wastewater treatment method comprising: an eleventh step of returning the filter aid separated by the solid-liquid separator to the filter aid storage tank. A first step of reacting water to be treated containing suspended particles and oil with a polymer flocculant;
A second step of supplying a coprecipitation agent containing a magnetic substance and having a primary particle diameter of 5 to 100 μm to the precipitation tank;
A third step of separating the treated water into suspended particles and primary treated water by gravity sedimentation;
A fourth step of transferring the slurry containing the suspended particles and the coprecipitate precipitated in the settling tank to a coprecipitate washing device;
A fifth step of separating and washing the slurry into a coprecipitate and suspended particles with a magnet;
A sixth step of supplying a filter aid containing a magnetic substance and having a primary particle size of 0.5 to 50 μm to the filter aid washing tank;
A seventh step of mixing primary treated water and the suspended particles and supplying them to a solid-liquid separator;
An eighth step of removing the filter aid deposited from the solid-liquid separator;
A ninth step of separating the filter aid and suspended particles;
An oil-containing wastewater treatment method comprising: a tenth step of returning the filter aid separated by the solid-liquid separator to the filter aid storage tank.

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