JP2010137178A - System and method for treating waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost and energy to be required to treat the waste sludge produced by an electrolysis treatment. <P>SOLUTION: The system 3 for treating waste water in order to remove a substance, which is to be removed and is contained in the waste water, from the waste water is characterized in that the sludge separated from impurity-containing water other than the waste water by electrolyzation is mixed in the waste water as an auxiliary flocculant in order to promote the flocculation of the substance, which is to be removed and is contained in the waste water, and a flocculated material produced by mixing the sludge in the waste water is removed from the waste water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wastewater treatment system for removing any object to be removed from wastewater.

Conventionally, there is a technique for aggregating impurities by reacting metal ions eluted in the water to be treated with the impurities (see Patent Document 1). In addition, there is a sewage treatment technology for supplying eluted iron ions or aluminum ions to a biofilm filtration tank (see Patent Documents 2 to 7).
JP 2006-122840 A Japanese Patent No. 3948779 JP 2006-110482 A JP 2008-194631 A JP 2007-203233 A JP 2005-246328 A JP 2007-237027 A

  Conventionally, there is an electrolysis method as a technique for removing impurities such as silica, iron and colloidal substances dissolved in water. The electrolysis method uses a soluble electrode made of iron, aluminum, etc. to elute metal ions (iron ions, aluminum ions, etc.) effective for agglomeration from the electrode by electrolysis, and removes negatively charged objects. This is a technique for aggregating and removing the object to be removed by reacting with (silica ion or the like). Further, in the electrolysis method, the adsorption of the colloidal substance by aluminum hydroxide is promoted by the effect of increasing the amount of hydroxide ions in the treated water by the generation of hydrogen gas from the negative electrode.

  FIG. 5 is a diagram showing a configuration of a conventional apparatus for removing a substance to be removed by electrolysis. The apparatus shown in FIG. 5 separates and removes an electrolysis reaction tank in which electrolysis is performed on the raw water in order from the upstream in the flow of water to be treated, and an object to be removed by precipitation of aggregates. A sedimentation tank in which

  In the electrolysis method, surplus sludge (a sludge having a relatively low viscosity) containing aggregates as a processing product is generated. The composition of the product is a substance to be removed such as silica and a compound of iron or aluminum. Therefore, excess sludge generated by electrolysis is a harmless substance similar to soil components. However, surplus sludge generated by the electrolysis method has been conventionally treated as industrial waste, so the surplus sludge treatment cost accounts for nearly half of the electrolysis treatment cost. Moreover, the excess sludge generated by the electrolysis method has a high moisture content as it is, and it is difficult to carry out and landfill, so dehydration and drying are necessary. Here, since the excess sludge generated by the electrolysis method has very poor dewaterability, it is difficult to dehydrate by a normal dehydration process, and much energy is required for the drying process by heating. Furthermore, the drying process by heating generates carbon dioxide, which is not preferable from the viewpoint of environmental considerations.

  In view of the above problems, an object of the present invention is to reduce the processing cost of surplus sludge generated by electrolysis and the energy required for the processing.

  In order to solve the above-mentioned problems, the present invention is a treatment process for aggregating waste water (processed raw water) containing contaminants, and agglomerating excess sludge generated in an impurity removal process by electrolysis of impurity-containing water separately. By putting it in the treatment process, it became possible to reduce the treatment cost of surplus sludge generated by electrolysis treatment and the energy required for treatment.

  Specifically, the present invention is a wastewater treatment system for removing a substance to be removed from wastewater from the wastewater, and sludge separated from treated water obtained by electrolyzing impurity-containing water other than the wastewater, A mixing means for mixing the waste water as a coagulation auxiliary substance for promoting the aggregation of the object to be removed in the waste water, and agglomerates produced by mixing the sludge with the waste water by the mixing means, And a separation means for separating from waste water.

  The wastewater treatment system according to the present invention is a system for removing a removal target (contaminant) from wastewater to be treated. For example, the wastewater to be treated may be any of food processing wastewater, machining wastewater, chemical factory wastewater, kitchen wastewater, domestic wastewater, or a composite water of these wastewaters. These wastewaters contain, for example, oil and SS components as removal objects. However, the removal target is not limited to specific substances such as oil and SS components, and a wide range of substances (particularly contaminants) contained in water can be the removal target.

  On the other hand, when electrolysis is used in water treatment (generally, treatment for removing impurities such as water-soluble silica from groundwater) performed separately from wastewater treatment in the wastewater treatment system according to the present invention, Surplus sludge containing agglomerates as a treated product (slurry sludge having a relatively low viscosity) is generated. Here, the inventor of the present application causes agglomeration of an object to be removed (oil or suspended matter) in wastewater to sludge containing agglomerates generated by electrolysis (different from agglomerates generated in a wastewater treatment system). It was found that it has the ability to promote, and the wastewater treatment system was changed to a wastewater treatment system using surplus sludge generated in electrolysis treatment as a coagulation auxiliary substance. That is, according to the present invention, surplus sludge is effectively used for wastewater treatment, so that it is possible to greatly reduce the processing cost for drying, transporting, landfilling, etc. of surplus sludge generated in electrolysis.

  Moreover, the waste water treatment system which concerns on this invention WHEREIN: The said mixing means may further mix the flocculant for promoting aggregation of the removal target object in this waste water with the said waste water.

  That is, in the present invention, the sludge as an agglomeration auxiliary substance may be used as an auxiliary agent that enhances the aggregating action of the aggregating agent by adding it to the process of aggregating the oil and SS components in the wastewater with the aggregating agent. . In addition, when wastewater treatment is performed by introducing only the sludge generated in the electrolysis process separately performed without introducing the flocculant into the wastewater, the sludge as the coagulant auxiliary substance is the same as the conventional flocculant. Used as an alternative. In any case, according to the present invention, the sludge generated in the electrolysis process in the wastewater treatment system is used as an agglomeration auxiliary substance, which not only reduces the cost and energy required for the treatment of excess sludge but also the conventional wastewater. It is also possible to reduce the flocculant used in the treatment.

In addition, sludge as a coagulant auxiliary substance may be mixed with wastewater in a coagulation treatment tank in which coagulation of the object to be removed is promoted by adding or stirring a coagulant, but other sludge in the flow of wastewater treatment It may be inserted at the time. For example, in the wastewater treatment system according to the present invention, the mixing means may be disposed outside the wastewater treatment system with respect to a pressurized levitation treatment tank for separating the aggregates generated in the wastewater by the pressurized levitation treatment. The sludge separated in the electrolysis treatment system may be mixed, and the mixing means is introduced into a pressure levitation treatment tank for separating the agglomerates generated in the wastewater by pressure levitation treatment. The sludge separated in the electrolysis treatment system outside the wastewater treatment system may be mixed with the flow rate adjustment tank for adjusting the flow rate of the wastewater to be produced.

  Further, the wastewater treatment system according to the present invention includes a pipe for introducing sludge separated from treated water obtained by electrolyzing impurity-containing water other than the wastewater in an electrolysis treatment system outside the wastewater treatment system. The mixing means may sequentially introduce sludge generated in the electrolysis processing system through the pipe and mix it with the waste water.

  According to the present invention, it is possible to further reduce the cost of transporting sludge and the like by directly introducing sludge from the water treatment system of another system using such a pipe.

  The wastewater treatment system according to the present invention is a storage for temporarily storing sludge separated from treated water obtained by electrolyzing impurity-containing water other than the wastewater in an electrolysis treatment system outside the wastewater treatment system. A means may further be provided, and the mixing means may mix the sludge stored by the storage means with the waste water.

  In this way, by temporarily storing sludge generated in the water treatment system of another system, according to the present invention, the stored sludge is thrown into a coagulation treatment tank or the like as needed and mixed with waste water. Is possible.

  The present invention can also be grasped as an invention of a water treatment method or an invention of an agglomeration auxiliary substance. For example, the present invention is a wastewater treatment method for removing a substance to be removed from wastewater from the wastewater, wherein sludge separated from treated water obtained by electrolyzing impurity-containing water other than the wastewater is treated with the wastewater. A mixing step in which the waste water is mixed as a coagulation auxiliary substance for promoting the aggregation of the object to be removed, and agglomerates generated by mixing the sludge with the waste water in the mixing step. And a separation step of separating.

  According to the present invention, it is possible to reduce the processing cost of excess sludge generated by electrolysis and the energy required for the processing.

  Embodiments of a wastewater treatment system according to the present invention will be described with reference to the drawings.

<First embodiment>
FIG. 1 is a schematic diagram showing the configuration of an electrolysis treatment system 1 and a wastewater treatment system 3 according to the first embodiment. The electrolysis treatment system 1 has an electrolysis reaction tank 12 and a precipitation tank 16 in order from the upstream in the flow of water to be treated. In addition, a pipe 11 for introducing impurity-containing water (treated water) is connected to the electrolysis reaction tank 12, and the electrolysis reaction tank 12 and the precipitation tank 16 are connected by a pipe 15. The settling tank 16 is connected to a pipe 17 for sending out treated water that has been subjected to the removal process of the removal object.

  Furthermore, the sedimentation tank 16 is connected to a pipe 18 and a pump 23 for feeding the sediment 22 precipitated in the lower part of the sedimentation tank 16 together with the water in the sedimentation tank 16, and the sediment sent out from the precipitation tank 16. The water containing is sent to the outside through the pipe 18. Hereinafter, in this embodiment, the water containing a sediment sent out from the sedimentation tank 16 is called sludge.

The electrolysis reaction tank 12 is a tank in which raw raw water to be treated is introduced via the pipe 11 and electrolysis is performed on the raw raw water. In addition, the impurity containing water used as the object of an electrolysis process is raw | natural water containing a removal target object, As a removal target object, the soluble silica melt | dissolved in the impurity containing water is mentioned, for example. However, the removal target is not limited to soluble silica, and in the electrolysis treatment system 1 according to the present invention, a wide range of removal target such as silica, iron, Mn (manganese), SS (Suspended Solids), etc. The substance can be removed, and the removal target is not limited to a specific substance. Further, the electrolysis process by the electrolysis means is a process of causing an electrolysis reaction by applying electric energy to the impurity-containing water from the outside, and aggregating and separating the objects to be removed. For example, by eluting metal ions such as aluminum ions from the electrode, the reaction efficiency with silica ions having a weakly acidic negative charge can be improved. For this reason, the electrolyzed water produced | generated by performing an electrolysis process contains the aggregate of a removal target object.

  In the electrolysis process according to this embodiment, a weakly acidic negative charge is obtained by eluting aluminum ions into water in the electrolysis reaction tank 12 from an aluminum electrode (not shown) provided in the electrolysis reaction tank 12. Promotes reaction with silica ions with In the electrolysis method, the adsorption of the colloidal substance by aluminum hydroxide is promoted by the effect of increasing the amount of hydroxide ions in the treated water by the generation of hydrogen gas from the negative electrode. By such an electrolysis process, aggregates are generated in the electrolysis reaction tank 12. Water containing aggregates (hereinafter referred to as electrolyzed water) that has been subjected to electrolysis in the electrolysis reaction tank 12 is sent to the precipitation tank 16 via the pipe 15.

  The settling tank 16 is a tank into which the electrolyzed water sent from the electrolysis reaction tank 12 is introduced and the aggregates are separated from the electrolyzed water. In the present embodiment, the electrolyzed water sent from the electrolysis reaction tank 12 stays in the settling tank 16 for a predetermined time, so that the object to be removed is separated and removed by precipitation of aggregates. The settled aggregate is accumulated in the lower part of the sedimentation tank 16 and becomes sludge. When the electrolyzed water stays in the settling tank 16 for a predetermined time, the agglomerates settle to the lower part of the settling tank 16, and an object to be removed (such as silica in this embodiment) is removed from the upper part of the settling tank 16. Treated water remains. The treated water from which the removal target has been removed is sent to the outside through the pipe 17 and can be used for various purposes. Moreover, when the sludge settles more than predetermined amount (when excess sludge generate | occur | produces), a sludge can be discharged | emitted by driving the pump 23 to the exterior (this embodiment wastewater treatment system 3).

  Next, the configuration of the wastewater treatment system 3 will be described. The wastewater treatment system 3 includes a coagulation treatment tank 33 and a precipitation tank 36 in order from the upstream in the flow of water to be treated. In addition, a pipe 32 for introducing waste water (raw raw water in the waste water treatment system 3) is connected to the coagulation treatment tank 33, and the coagulation treatment tank 33 and the precipitation tank 36 are connected by a pipe 35. The settling tank 36 is connected with a pipe 37 for sending out treated water that has been subjected to the removal treatment of the removal object.

  Further, a pipe 31 for introducing the sludge generated in the electrolysis treatment system 1 into the coagulation treatment tank 33 is connected to the coagulation treatment tank 33, and the sludge sent out from the sedimentation tank 16 of the electrolysis treatment system 1. Is mixed with the waste water in the agglomeration treatment tank 33 through the pipe 31. That is, in the present embodiment, the pipe 31 is connected to the pipe 18 of the electrolysis processing system 1. Moreover, in this embodiment, in order to accelerate | stimulate mixing with the waste water introduce | transduced into the coagulation processing tank 33, sludge, and a coagulant | flocculant, stirring by the stirring apparatus 34 is performed.

  The sedimentation tank 36 is connected to a pipe 39 and a pump 38 for sending the sediment 40 precipitated at the bottom of the sedimentation tank 36 together with the water in the sedimentation tank 36. The sediment sent out from the precipitation tank 36 is connected to the sedimentation tank 36. Water (excess sludge 2 shown in FIG. 1) is sent to the outside through the pipe 39.

The agglomeration treatment tank 33 is a tank into which waste water to be treated is introduced via the pipe 32 and the agglomeration treatment of the removal target is performed on the waste water. In the flocculation process according to the present embodiment, the sludge introduced from the pipe 31 provided in the flocculation treatment tank 33 and the flocculant introduced into the flocculation treatment tank 33 promote the flocculation of the removal target in the wastewater. By such agglomeration treatment, agglomerates are generated in the agglomeration treatment tank 33. The water containing aggregates (hereinafter referred to as aggregated treated water) subjected to the aggregation treatment in the aggregation treatment tank 33 is sent to the precipitation tank 36 via the pipe 35.

  The sedimentation tank 36 is a tank into which the agglomerated water sent from the agglomeration processing tank 33 is introduced and the agglomerates are separated from the agglomerated water. In the present embodiment, the agglomerated water sent from the agglomeration treatment tank 33 stays in the sedimentation tank 36 for a predetermined time, so that the removal target object is separated and removed by precipitation of the agglomerates. The precipitated agglomerates become sludge by collecting in the lower part of the settling tank 36. When the agglomerated water stays in the sedimentation tank 36 for a predetermined time, the agglomerate settles to the lower part of the sedimentation tank 36, and an object to be removed (in this embodiment, oil component, SS component, etc.) is present at the upper part of the sedimentation tank 36. The removed treated water remains. The treated water from which the removal target has been removed is sent to the outside through the pipe 37 and sent to a biological treatment plant or the like for further processing. Further, when the sludge has settled over a predetermined amount, the sludge can be discharged to the outside by driving the pump 38.

<Second Embodiment>
FIG. 2 is a schematic diagram showing the configuration of the electrolysis treatment system 1 and the wastewater treatment system 3b according to the second embodiment. Here, since the configuration of the electrolysis processing system 1 according to the present embodiment is substantially the same as that of the first embodiment, detailed description thereof is omitted. However, the configuration of the electrolysis treatment system 1 shown in the first embodiment and the second embodiment is an example, and the electrolysis treatment system in which sludge introduced into the wastewater treatment system shown in the present embodiment is generated. An electrolysis processing system having other configurations may be employed.

  The wastewater treatment system 3b includes a flocculation treatment tank 33 and a pressure levitation treatment tank 41 in order from the upstream in the flow of water to be treated. The agglomeration treatment tank 33 is connected with a pipe 32 for introducing waste water (raw raw water in the waste water treatment system 3b), and the agglomeration treatment tank 33 and the pressurized levitation treatment tank 41 are connected with a pipe 35. The pressurized levitation treatment tank 41 is connected with a pipe 37 for sending out treated water that has been subjected to removal treatment of the removal object.

  The coagulation treatment tank 33 is connected to a pipe 31 for introducing the sludge generated in the electrolysis treatment system 1 into the coagulation treatment tank 33. The wastewater treatment system 3b according to this embodiment is an electrolysis treatment system. The sludge storage tank 42 for storing the sludge sent from 1 through the pipe 18 is provided. The sludge stored in the sludge storage tank 42 is sent to the aggregation treatment tank 33 via the pipe 31 by the pump 43 that operates as necessary. That is, the wastewater treatment system 3b according to the present embodiment is electrolyzed in that the sludge generated in the electrolysis process is once stored in the sludge storage tank 42 and then supplied to the coagulation treatment tank 33 as necessary. It differs from the wastewater treatment system 3 according to the first embodiment in which sludge generated in the treatment system 1 is continuously charged.

In addition, in the wastewater treatment system 3b which concerns on this embodiment, the pressure flotation separation method is employ | adopted as a separation method of an aggregate, and the wastewater treatment system 3b replaces a sedimentation tank as a separation method of sludge (aggregate). It differs from the wastewater treatment system 3 according to the first embodiment in that it has a pressurized flotation treatment tank 41. In the pressurized flotation separation method, the agglomerates are separated from water by wrapping the agglomerates with fine bubbles that are generated when the pressurized water in which the gas is dissolved is decompressed in the pressurized flotation treatment tank 41, and floating. This is a method for separating aggregates. However, in the wastewater treatment system 3 according to the first embodiment and the wastewater treatment system 3b according to this embodiment, the precipitation method and the pressure flotation separation method are used as the separation means for the agglomerate and water. The technique used for the separation is not limited to the technique shown in the embodiment as long as it can separate the aggregates.

<Other embodiments>
In this embodiment, the case where the sludge is used as an auxiliary agent for the flocculant has been described. However, when the amount of waste water to be treated is small or the concentration of the removal target in the waste water is low, the sludge is removed. In some cases, removal of an object to be removed can function sufficiently only by charging. In this case, a flocculant is not necessary.

  Moreover, although this embodiment demonstrated the case where sludge was mixed with wastewater in the coagulation treatment tank 33, the effect of coagulation of impurities due to sludge can be expected even when the sludge is added in a process in which the coagulant is not added. Specifically, in each process of wastewater treatment, sludge is pressurized, for example, in the process of treating oil and SS components (floating matter that can be filtered with filter paper) only by pressure flotation without introducing flocculant. It is good also as throwing into the flow volume adjustment tank (illustration omitted) before a levitation process. In this case, since the cohesiveness can be improved before the pressure levitation treatment, the removal performance in the pressure levitation treatment after the sludge is charged can be improved. Further, the sludge may be supplied to the pressurized levitation treatment tank 41.

  Conventionally, the flow of wastewater treatment containing oil and SS components is obtained by sequentially performing screen treatment of wastewater (treated raw water), agglomeration treatment with a flocculant, and a separation treatment of agglomerates in order. The treated water is discharged into the sewage, the screen treatment of the waste water (raw raw water), the flocculation treatment with the flocculant, the separation treatment of the flocculate, and the biological treatment of the water from which the flocculate has been removed are sequentially performed. In general, a process in which treated water obtained by applying water is discharged into sewage or rivers. The sludge generated by the electrolysis treatment in the present invention can be used as a coagulant auxiliary agent or an alternative to the coagulant in the above-exemplified waste water treatment process.

  The present invention has the ability to agglomerate removal objects (oils and suspended substances) in wastewater on sludge containing agglomerates generated by electrolysis (different from agglomerates generated in a wastewater treatment system). It was made paying attention to the fact that was found. And according to the wastewater treatment systems 3 and 3b according to this embodiment, the sludge generated by the electrolysis treatment is used as a coagulation auxiliary substance in the wastewater treatment, so that the treatment cost and the treatment of the excess sludge generated by the electrolysis treatment are used. It is possible to reduce the energy required for the coagulant and further reduce the cost of the flocculant in the wastewater treatment.

  In order to confirm the effectiveness of the present invention over the prior art, a test system of the present invention was manufactured and a comparative experiment was performed. In this example, sludge generated by electrolysis using an aluminum electrode whose main purpose is to remove silica contained in groundwater was used in an agglomeration process in organic wastewater treatment at a food processing plant. Further, in this example, since the amount of flocculant used is large, the waste water treatment system 3 having the configuration shown in the first embodiment described with reference to FIG. 1 is used as the test system of the present invention. The sludge generated by the electrolysis process was continuously supplied to the coagulation treatment tank 33.

  FIG. 3 is a view showing the agglomeration treatment tank 33 used in the test system according to the present embodiment, and FIG. 4 is a view showing the agitation propeller used in the agglomeration treatment tank 33 of the test system according to the present embodiment. It is. In the test system, a flocculation treatment tank 33 having a square shape with a bottom of 250 mm (millimeters) on the inside and a depth of 400 mm is used as an internal dimension, and electrolyzed water is introduced into the flocculation treatment tank 33 to a water depth of 270 mm. The test was conducted. Further, as the stirring propeller, one in which four blades having a length of 30 mm and a height of 25 mm in a direction orthogonal to the rotation axis are attached at intervals of 90 degrees around the rotation axis is used.

  In this example, in the test system, a case where wastewater treatment was performed only with a flocculant without introducing sludge, and a case where wastewater treatment was performed by adding sludge as an auxiliary agent for the flocculant, The reduction effect of the flocculant according to the present invention was confirmed by comparing the amount of the flocculant added in order to obtain equivalent treated water (that is, to obtain the same flocculation effect). The amount of flocculant added to obtain treated water of a predetermined condition when no sludge is charged and the amount of flocculant charged to obtain treated water of the same condition when sludge is charged The comparison is shown in Table 1.

  As shown in Table 1, in this example, when sludge (water content 99.5%) generated in the electrolysis treatment was added at a rate of 500 g (grams) / t (tons), It was confirmed that with 16 g of flocculant, the same treated water as when 20 g of flocculant was added per 1 ton of wastewater without adding sludge was obtained, that is, the flocculant could be reduced by 20% by introducing sludge. . That is, in this example, according to the test system according to the present invention, the cost of the flocculant is reduced by 20%, and further, the treatment cost of the sludge generated by the electrolysis treatment that was conventionally treated with industrial waste is reduced. It was shown that.

It is the schematic which shows the structure of the electrolysis processing system and waste water treatment system which concern on 1st embodiment. It is the schematic which shows the structure of the electrolysis processing system and waste water treatment system which concern on 2nd embodiment. It is a figure which shows the aggregation treatment tank used in the test system which concerns on an Example. It is a figure which shows the stirring propeller used in the aggregation processing tank of the test system which concerns on an Example. It is a figure which shows the structure of the conventional apparatus which removes the removal target substance by the electrolysis method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolytic treatment system 3 Waste water treatment system 12 Electrolysis reaction tank 22 Precipitate 33 Coagulation treatment tank 36 Precipitation tank

Claims (7)

A wastewater treatment system for removing substances to be removed from wastewater from the wastewater,
Mixing means for mixing the sludge separated from the treated water obtained by electrolyzing the impurity-containing water other than the waste water with the waste water as a coagulation auxiliary substance for promoting the aggregation of the removal target in the waste water;
A separation means for separating the agglomerate produced by mixing the sludge with the wastewater by the mixing means from the wastewater;
A wastewater treatment system comprising. The mixing means further mixes a coagulant for promoting the coagulation of the object to be removed in the wastewater with the wastewater.
The wastewater treatment system according to claim 1. The mixing means is a sludge separated in an electrolysis treatment system outside the wastewater treatment system with respect to a pressurized flotation treatment tank for separating agglomerates generated in the wastewater by a pressure flotation treatment. Mixing,
The wastewater treatment system according to claim 1. The mixing means is provided with respect to a flow rate adjusting tank for adjusting a flow rate of waste water introduced into a pressurized flotation treatment tank for separating agglomerates generated in the wastewater by a pressurized flotation treatment. Mixing the sludge separated in the electrolytic treatment system outside the treatment system,
The wastewater treatment system according to claim 1. A pipe for introducing sludge separated from treated water obtained by electrolyzing impurity-containing water other than the wastewater in an electrolysis treatment system outside the wastewater treatment system;
The mixing means sequentially introduces the sludge generated in the electrolysis processing system through the pipe and mixes it with the waste water.
The wastewater treatment system according to any one of claims 1 to 4. A storage means for temporarily storing sludge separated from the treated water obtained by electrolyzing impurity-containing water other than the wastewater in the electrolysis treatment system outside the wastewater treatment system;
The mixing means mixes the sludge stored by the storage means with the waste water.
The wastewater treatment system according to any one of claims 1 to 4. A wastewater treatment method for removing substances to be removed from wastewater from the wastewater,
A mixing step of mixing the sludge separated from the treated water obtained by electrolyzing the impurity-containing water other than the waste water with the waste water as a coagulation auxiliary substance for promoting the aggregation of the removal target in the waste water;
A separation step of separating the agglomerates generated by mixing the sludge with the wastewater in the mixing step from the wastewater;
Wastewater treatment method that is implemented.

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