JP6869094B2 - Metal-containing wastewater treatment method and metal-containing wastewater treatment system - Google Patents

Description

The present invention relates to a method for treating metal-containing wastewater and a system for treating metal-containing wastewater.

As a treatment method for removing metal ions from wastewater containing metal ions (hereinafter, may be simply referred to as "treatment method"), for example, metal ions dissolved in wastewater are treated as metal hydroxides or metal sulfides. There are a method of changing to an insoluble compound such as, and a method of removing metal ions dissolved in wastewater as a metal chelate.

In the above-mentioned treatment method, the metal dissolved in the waste water is precipitated as a floc (insoluble substance), and then the flocs are subjected to solid-liquid separation treatment such as precipitation separation, filtration separation, and centrifugation, and the metal is discharged from the waste water. Need to be removed. Among the above-mentioned solid-liquid separation treatments, sedimentation separation using the weight of flocs is often used from the viewpoint of suppressing the treatment cost. Generally, in sedimentation separation, in order to ensure the treatment efficiency, the smaller the sedimentation rate of flocs, the smaller the sedimentation tank. It is necessary to increase the scale (installation area) of.

As a method of increasing the flock removal efficiency and reducing the scale of the settling tank, a method of increasing the effective processing area by installing an inclined plate (see, for example, Patent Document 1 and Patent Document 2). Methods for increasing the precipitation rate of flocs by applying various flocculants (see, for example, Patent Documents 3 and 4) have been proposed and put into practical use.

Japanese Unexamined Patent Publication No. 2001-327981 Japanese Unexamined Patent Publication No. 2002-136808 Japanese Unexamined Patent Publication No. 2011-031229 Japanese Unexamined Patent Publication No. 2016-026781

However, in the method of increasing the removal efficiency of flocs by using the inclined plate as described above, the removal rate is 100% (removal rate is 100%) due to restrictions on the processing amount and the installation area, especially when removing flocs having a low sedimentation speed. It becomes difficult to achieve a high removal rate of about 100%).
In addition, even in the method of increasing the sedimentation rate of flocs by applying various flocculants, there is a limit to growing large flocs by devising the flocculants, and the treatment cost is increased by using a special flocculant. It will increase.

Based on the above circumstances, recently, a treatment method in which a pH adjusting tank (that is, an alkali treatment tank), a coagulant stirring tank, and a settling tank are combined into one tank has been studied. In this treatment method, (1) it is not always necessary to remove all the flocs (that is, the removal rate does not have to reach 100%), and (2) the flocs circulating inside the tank are metallic water. Since it becomes the core when precipitated as an oxide, flocs with high precipitation performance are generated, (3) the amount of alkaline agent added to wastewater can be reduced, and (4) pumps connecting each tank and Effects such as no need for piping can be obtained. However, although the above-mentioned treatment method can obtain the effect described in (3) above, a large amount of acid is required to adjust the pH of the alkaline agent and the treated water within the range of the wastewater standard value. The problem remained.

The present invention has been made in view of the above circumstances, and the use of an acid (hereinafter, may be simply referred to as "acid") for adjusting the pH of an alkaline agent or treated water within the range of the wastewater standard value. Provided are a method for treating metal-containing wastewater and a treatment system for metal-containing wastewater, which can reduce the amount.

The method for treating metal-containing wastewater according to claim 1 is a method for treating metal-containing wastewater for removing metal from metal-containing wastewater, and supplies raw water for supplying the metal-containing wastewater into an annular treatment flow path. A step, a circulation step of flowing and circulating the metal-containing wastewater supplied into the treatment flow path in a predetermined direction in the treatment flow path, and a pH adjuster applied to the metal-containing wastewater in the treatment flow path. A pH adjustment step of adding and adjusting the pH of the metal-containing wastewater, a flocculant addition step of adding a flocculant to the metal-containing wastewater whose pH has been adjusted, and collecting flocs aggregated and settled by the flocculant. and floc collection step of, and downstream of the circulating water the flock is collected in the processing passage, electrolysis, and supernatant water discharged to the outside of the flock is collected the processing flow paths It is characterized by having an electrolysis process.

According to the above configuration, in the electrolysis step, a chemical agent (that is, an acid) for adjusting the pH of the supernatant water by electrolyzing the circulating water and the supernatant water which have been subjected to the pH treatment in advance in the pH adjusting step. ) Is not required. In addition, an alkaline agent (that is, circulating water) added to metal-containing wastewater (that is, circulating water) in the circulation process by generating hydroxide ions corresponding to the acid used to adjust the pH of the supernatant water on the cathode side. The amount of pH adjuster) can be reduced. Furthermore, the accumulation of salts (sodium ions in the case of sodium hydroxide) paired with the above-mentioned hydroxide ions and hydrogen ions can be suppressed.

The method for treating metal-containing wastewater according to claim 2 is a method for treating metal-containing wastewater for removing metal from metal-containing wastewater, and supplies raw water for supplying the metal-containing wastewater into an annular treatment flow path. A step, a circulation step of flowing and circulating the metal-containing wastewater supplied into the treatment flow path in a predetermined direction in the treatment flow path, and a pH adjuster applied to the metal-containing wastewater in the treatment flow path. A pH adjustment step of adding and adjusting the pH of the metal-containing wastewater, a flocculant addition step of adding a flocculant to the metal-containing wastewater whose pH has been adjusted, and collecting flocs aggregated and settled by the flocculant. Flock collection step, a second pH adjustment step of adding a pH adjusting solution to the supernatant water in which the flocs are collected to adjust the pH of the supernatant water, and the flocs being collected in the treatment flow path. It is characterized by comprising an electrolysis step of electrolyzing the collected circulating water on the downstream side and the solution filled in the tank for preparing the pH adjusting solution inside.
In the method for treating metal-containing wastewater according to claim 3, the content of the halogen compound in the pH adjusting liquid is preferably 0.2% by mass or less in the above-mentioned method for treating metal-containing wastewater.

According to the above configuration, in the electrolysis step, for example, acidic water is produced by electrolyzing the circulating water that has been pre-treated with pH in the pH adjusting step and the solution filled in the pH adjusting solution preparation tank. The acid water can be prepared and the pH of the supernatant water can be adjusted so as to satisfy the wastewater standard to prepare the final treated water. Further, the amount of acid used can be suppressed as in the above-mentioned method for treating metal-containing wastewater.
Further, when the content of the halogen compound in the pH adjusting solution is as small as 0.2% by mass or less, acidic water can be smoothly produced.

The metal-containing wastewater treatment system according to claim 4 is a system for removing metal from metal-containing wastewater, and includes an annular treatment flow path for temporarily storing the metal-containing wastewater to be treated. A raw water supply unit for supplying the metal-containing wastewater inside the treatment flow path and a flow generating means for flowing and circulating the metal-containing wastewater inside the treatment flow path in a predetermined direction are provided. In the treatment flow path, a pH adjusting unit for adjusting the pH of the metal-containing wastewater by adding a pH adjusting agent to the metal-containing wastewater, a flocculant addition unit for adding a flocculant to the metal-containing wastewater, and the agglomeration The floc collecting section is provided with a floc collecting section for collecting flocs aggregated and settled by the agent, and a pH adjusting tank for adjusting the pH of the supernatant water in which the flocs are collected. It is characterized by further including an electrolysis unit having a cathode arranged on the downstream side of the above, an anode arranged inside the pH adjusting tank, and a power source.

According to the above configuration, the amount of acid used can be suppressed by electrolyzing the circulating water and the supernatant water which have been subjected to pH treatment in advance in the pH adjusting step by the electrolysis unit. In addition, an alkaline agent added to metal-containing wastewater (that is, circulating water) in the treatment flow path by generating hydroxide ions corresponding to the acid used to adjust the pH of the supernatant water at the cathode. The amount of (pH adjuster) can be suppressed. Furthermore, the accumulation of salts (sodium ions in the case of sodium hydroxide) paired with the above-mentioned hydroxide ions and hydrogen ions is suppressed.

The metal-containing wastewater treatment system according to claim 5 is a system for removing metal from metal-containing wastewater, and includes an annular treatment flow path for temporarily storing the metal-containing wastewater to be treated. A raw water supply unit for supplying the metal-containing wastewater inside the treatment flow path and a flow generating means for flowing and circulating the metal-containing wastewater inside the treatment flow path in a predetermined direction are provided. In the treatment flow path, a pH adjusting unit for adjusting the pH of the metal-containing wastewater by adding a pH adjusting agent to the metal-containing wastewater, a coagulant adding part for adding a coagulant to the metal-containing wastewater, and the agglomeration. A flock collecting section that collects flocs aggregated and settled by the agent, a pH adjusting tank that adjusts the pH of the supernatant water in which the flocs are collected, and a pH adjusting solution for adjusting the pH of the supernatant water. It is provided with a pH adjusting liquid preparation tank to be prepared, and has a cathode arranged on the downstream side of the floc collecting portion in the processing flow path, an anode arranged inside the pH adjusting liquid preparing tank, and a power source. It is characterized by further including an electrolysis unit.
In the metal-containing wastewater treatment system according to claim 6, the content of the halogen compound in the solution filled in the pH adjusting liquid preparation tank is preferably 0.2% by mass or less.

According to the above configuration, in the electrolysis unit, for example, acidic water is produced by electrolyzing the circulating water and the pH adjusting liquid which have been subjected to pH treatment in advance in the pH adjusting step, and the acidic water is used. The pH of the supernatant water is adjusted to meet the effluent standards and the final treated water is obtained. In addition, the amount of acid used can be suppressed as in the above-mentioned metal-containing wastewater treatment system.
Further, since the inside of the pH adjusting liquid preparation tank is filled with a solution having a low halogen compound content, acidic water is smoothly generated.

According to the method for treating metal-containing wastewater and the treatment system for metal-containing wastewater according to the present invention, the amount of acid used can be suppressed.

It is a figure of the metal-containing wastewater treatment system of the 1st Embodiment to which this invention was applied, the upper part is a plan view, and the lower part is a side view. It is a figure of the metal-containing wastewater treatment system of the 2nd Embodiment to which this invention was applied, the upper part is a plan view, and the lower part is a side view.

Hereinafter, embodiments of a method for treating metal-containing wastewater to which the present invention is applied will be described. The drawings used in the following description are schematic, and the length, width, thickness ratio, etc. are not always the same as the actual ones and can be changed as appropriate.

(First Embodiment)
First, an example of a metal-containing wastewater treatment system (hereinafter, may be simply referred to as a “treatment system”) according to the first embodiment to which the present invention is applied will be described.

As shown in FIG. 1, the metal-containing wastewater treatment system B of the first embodiment has an annular treatment flow path 2 for temporarily storing the wastewater 1 to be treated and a metal-containing wastewater treatment inside the treatment flow path 2. The raw water supply unit 3 that supplies 1a, the flow generating means 4 for flowing and circulating the wastewater 1 inside the treatment flow path 2 in the T direction (one direction), and the circulation whose pH is adjusted in the treatment flow path 2. It is provided with an electrolysis means 20 for electrolyzing the water 29 and the treated water (supernatant water) taken out from the treatment flow path 2.

The treatment flow path 2 is composed of a pH adjusting unit 6 that adds a pH adjusting agent 5 to the waste water 1 to adjust the pH of the waste water 1, a coagulant adding unit 8 that adds a coagulant 7 to the waste water 1, and a coagulant 7. It is provided with a flock collecting unit 9 for collecting flocs that have aggregated and settled.

Further, in the processing system B, the flock collecting unit 10 for discharging the flock collected in the flock collecting unit 9 from the flock collecting unit 9 to the outside of the processing flow path 2 and collecting the flock, and the flocs settle down. It is provided with a water collecting trough 11 for taking in the supernatant water of the drainage 1 and discharging it to the outside of the treatment flow path 2, and a rectifying means 12 for adjusting the flow of the drainage 1.

The flow generating means 4 is for creating a flow in the T direction of the waste water 1 inside the annular treatment flow path 2 and circulating the waste water 1. Further, the flow generating means 4 includes a shaft portion 4a that is rotationally driven around the axis, and a plurality of rotating plates 4b that extend radially from the shaft portion 4a. Further, the flow generating means 4 is configured so that a plurality of rotating plates 4b rotating around the axis together with the shaft portion 4a sequentially push the drainage 1 in the T direction to create a flow in the T direction, and thus a circulating flow. There is.

The coagulant addition unit 8 is provided between the pH adjusting unit 6 of the treatment flow path 2 and the flow generating means 4. The coagulant addition unit 8 adds a coagulant 7 such as an anionic polymer coagulant to the waste water 1 whose pH has been adjusted by the pH adjustment unit 6 to coagulate and grow the flocs of the hydroxide. belongs to. The coagulant addition unit 8 is provided with a stirring means 13 for mixing and stirring the added coagulant 7 and the waste water 1.

The flock collecting portion 9 is provided on the downstream side in the T direction with respect to the flow generating means 4. The floc collecting section 9 is for collecting flocs that grow by adding the flocculant 7 in the flocculant adding section 8 and settle on the bottom surface 2a of the treatment flow path 2 so as to be deposited. Further, the flock collecting portion 9 gradually inclines downward from the bottom surface 2a of the processing flow path 2 from the upstream side to the downstream side, and gradually inclines upward from the lowest portion 2b toward the downstream side. It has 14.

The flock collection unit 10 collects the flock in the flock collection unit 9, and discharges the collected flock accumulated in the lowest portion 2b (flock accumulation recess 14) of the flock collection unit 9 to the outside of the processing flow path 2. It is for recovery. The flock collection unit 10 includes, for example, a collection pipe (not shown) connected to a flock collection port that opens at the bottom surface of the lowest portion 2b of the flock collection unit 9, and a pump for pulling out the flock from the processing flow path 2 through the collection pipe. The recovery driving means (not shown) is provided.

The water collecting trough 11 is provided, for example, on the T-direction downstream side of the drainage 1 with respect to the flock collecting part 9. The catchment trough 11 is for taking in the supernatant water of the drainage 1 after the flocs have settled and discharging it to the outside of the treatment flow path 2. The position of the catchment trough 11 is not particularly limited as long as it is possible to take in the supernatant water of the drainage 1 and discharge it to the outside of the system.

The rectifying means 12 is provided between the flow generating means 4 and the flock collecting unit 9. The rectifying means 12 is for adjusting the flow of the turbulent drainage 1 by stirring and mixing by the stirring means 13 and sending it to the floc collecting unit 9. The rectifying means 12 includes, for example, a plurality of rectifying plates arranged in parallel at predetermined intervals.

In the treatment system B, the flow generating means 4 creates a flow in the T direction with respect to the wastewater 1 in the treatment flow path 2, and the wastewater 1 circulates in the annular treatment flow path 2. Further, the raw water 1a of the metal-containing wastewater is appropriately supplied from the raw water supply unit 3 to the circulating flow of the wastewater 1.

Then, the pH adjusting agent 5 is added to the waste water 1 circulating in the treatment flow path 2 by the pH adjusting unit 6, and the pH of the waste water 1 is adjusted to a predetermined pH by being stirred by the stirring means 13. When the pH is adjusted in this way, the metal ions in the waste water 1 become hydroxides and flocs are formed.

The drainage 1 containing the flocs formed in the pH adjusting section 6 reaches the coagulant adding section 8, the coagulant 7 is added, and the agitating means 13 agitates and mixes the fine flocs, so that the fine flocs are aggregated and become large. It grows into a flock.

The drainage 1 that has passed through the coagulant addition portion 8 passes through the rectifying means 12, and the flow of the drainage 1 disturbed by the stirring means 13 is adjusted.

The large flocs contained in the waste water 1 gradually settle due to their own weight and reach the bottom surface 2a of the treatment flow path 2. The bottom surface 2a of the processing flow path 2 has a floc collecting portion 9 that gradually inclines downward toward the downstream side in the T direction, reaches the lowest portion 2b, and then gradually inclines upward toward the downstream side in the T direction. Since the flock accumulation recess 14 is provided, the flock that reaches the bottom surface 2a of the processing flow path 2 while moving along with the flow of the drainage 1 is automatically collected and accumulated in the flock accumulation recess 14 of the flock collecting portion 9. ..

The lowest portion 2b of the flock collecting portion 9 is provided with a flock collecting port for discharging the flock from the inside of the processing flow path 2 to the outside. The flock collected and accumulated by the flock collecting unit 9 is discharged / extracted from the flock collection port to the outside of the processing flow path 2 at an appropriate timing, and is dehydrated by the dehydration processing apparatus 15. As a result, the metal in the metal-containing wastewater 1a is removed and disposed of as the dehydrated cake 16.

The supernatant water (treated water in which the flocs have settled and cleaned) 17 of the drainage inside the treatment flow path 2 is taken in by the water collecting trough 11 and discharged to the outside of the treatment flow path 2. The pH of the supernatant water 17 is adjusted in the pH adjusting tank 18. The adjusted supernatant water 17 is discharged as final treated water 19.

The electrolysis means 20 includes a power source 31, a cathode 33 (so-called cathode) connected to the negative electrode of the power source 31, and an anode 35 (so-called anode) connected to the positive electrode of the power source 31. The cathode 33 is arranged inside the treatment flow path 2 on the downstream side of the catchment trough 11 in the T direction. The anode 35 is arranged inside the pH adjusting tank 18.

In the above configuration, the circulating water 29 to which the pH adjusting agent 5 has already been added and the pH has been adjusted inside the treatment flow path 2 and the supernatant water 17 whose pH has been adjusted in the pH adjusting tank 18 are electrolyzed to obtain the supernatant. Hydroxide ions corresponding to the acid used to adjust the pH of water 17 are generated at the cathode 33. The generated hydroxide ion is added to the circulating water 29, and the circulating water 29 circulates in the T direction.

The method for treating metal-containing wastewater of the first embodiment to which the present invention is applied (hereinafter, may be simply referred to as “treatment method”) is a treatment method using treatment system B, and is a treatment method using an annular treatment flow path 2. A raw water supply step of supplying metal-containing wastewater to the inside, a circulation step of flowing the metal-containing wastewater supplied to the inside of the treatment flow path 2 in the T direction (predetermined direction) and circulating it inside the treatment flow path 2. A pH adjustment step of adding a pH adjuster 5 to the metal-containing wastewater inside the treatment flow path 2 to adjust the pH of the metal-containing wastewater, and adding a coagulant 7 to the metal-containing wastewater whose pH has been adjusted. The step, the flock collecting step of collecting the flocs aggregated and settled by the flocculant 7, the circulating water 29 on the downstream side where the flocs were collected inside the treatment flow path 2, and the supernatant water where the flocs were collected. It is provided with an electrolysis step of electrolyzing 17 and.

Therefore, in the metal-containing wastewater treatment system B and the treatment method of the first embodiment, the pH of the supernatant water is adjusted by electrolyzing the circulating water and the supernatant water that have been previously pH-treated in the pH adjustment step. You don't need a lot of chemicals (ie, acids) to do this. Further, by generating hydroxide ions corresponding to the acid used for adjusting the pH of the supernatant water at the cathode 33, an alkaline agent added to the metal-containing wastewater (that is, circulating water 29) in the circulation step. The amount of (pH adjuster) can be reduced. Furthermore, the accumulation of salts (sodium ions in the case of sodium hydroxide) paired with the above-mentioned hydroxide ions and hydrogen ions can be suppressed.

Further, in the metal-containing wastewater treatment system B of the first embodiment, the flocs that could not be completely removed are automatically circulated a plurality of times while being treated in each part, so that the flocs that could not be completely removed are circulated a plurality of times. It can be reliably grown into large flocs in the circulation and removed.

Further, by configuring the plurality of treatments to be continuously performed in one system, the amount of the pH adjuster 5 added to the metal-containing wastewater can be reduced, and further, the conventional treatment steps are connected. Pumps and piping can be eliminated.

Therefore, according to the metal-containing wastewater treatment system B of the first embodiment, even a floc having a low settling speed can be more effectively and economically settled and separated and surely removed.

(Second Embodiment)
Next, the processing system and the processing method of the second embodiment to which the present invention is applied will be described. Among the components of the processing system of the second embodiment, the components common to the processing system B of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 2, the treatment system C of the second embodiment prepares a pH adjusting liquid 30 for internally adjusting the pH of the supernatant water 17 in addition to the configuration of the treatment system B of the first embodiment. The pH adjusting liquid preparation tank 40 is provided. Further, the anode 35 of the electrolysis means 20 is arranged inside the pH adjusting liquid preparation tank 40.

In order to smoothly prepare acidic water as the pH adjusting liquid 30, the content of the halogen compound in the solution 44 filled inside the pH adjusting liquid making tank 40 is 0% by mass or more and 0.2% by mass or less. It is preferable to have. That is, it is preferable that the pH adjusting liquid preparation tank 40 is filled with a solution 44 that does not contain a high concentration of halogen elements (for example, tap water that does not contain a high concentration of halogen elements, such as seawater).

The method for treating metal-containing wastewater of the second embodiment to which the present invention is applied (hereinafter, may be simply referred to as “treatment method”) is a treatment method using treatment system C, and is a treatment method using an annular treatment flow path 2. A raw water supply step of supplying metal-containing wastewater to the inside, a circulation step of flowing the metal-containing wastewater supplied to the inside of the treatment flow path 2 in the T direction (predetermined direction) and circulating it inside the treatment flow path 2. A pH adjustment step of adding a pH adjuster 5 to the metal-containing wastewater inside the treatment flow path 2 to adjust the pH of the metal-containing wastewater, and adding a coagulant 7 to the metal-containing wastewater whose pH has been adjusted. A second step of adjusting the pH of the supernatant water 17 by adding a pH adjusting solution 30 to the supernatant water 17 in which the flocs are collected, and a flock collecting step of collecting the flocs aggregated and settled by the flocculant 7. The pH adjustment step of the above and the electrolysis step of electrolyzing the circulating water 29 and the solution 44 on the downstream side where flocs are collected inside the treatment flow path 2 are provided.

Therefore, in the treatment system C and the treatment method for metal-containing wastewater of the second embodiment, the circulating water 29 which has been treated with pH in advance and the solution 44 filled in the pH adjusting liquid preparation tank 40 are electrolyzed. For example, acidic water (functioning as the pH adjusting liquid 30) can be prepared, and the pH of the supernatant water 17 can be adjusted using the acidic water so as to satisfy the drainage standard to obtain the final treated water 19. Further, in the treatment system C and the treatment method, the amount of acid used can be suppressed as in the treatment system B and the treatment method of the first embodiment.
Further, since the pH adjusting liquid preparation tank 40 is filled with the solution 44 containing no halogen element as described above, acidic water can be smoothly generated.
Such a treatment system C and a treatment method are particularly useful for treating wastewater containing a large amount of salt such as petroleum-related water from which oil has been removed.

Although one embodiment of the metal-containing wastewater treatment system according to the present invention has been described above, the present invention is not limited to the above-mentioned one embodiment and can be appropriately changed without departing from the spirit of the present invention.

For example, the arrangement and number of the catchment troughs 11 may be devised so that the catchment troughs 11 are used to reduce the flow velocity of the drainage 1 and promote the sedimentation of the flocs. That is, the arrangement and number of the catching troughs 11 may be determined so as to improve the collecting efficiency of the flock in the flock collecting section 9.

2 ... Treatment flow path, 3 ... Raw water supply section, 4 ... Flow generating means, 5 ... pH adjusting agent, 6 ... pH adjusting section, 7 ... Aggregating agent, 8 ... Aggregating agent adding section, 9 ... Flock collecting section, 10 ... Flock recovery unit, 17 ... supernatant water, 18 ... pH adjustment tank, 19 ... final treatment water, 29 ... circulating water, 30 ... pH adjustment liquid, 40 ... pH adjustment liquid preparation tank (tank for preparing pH adjustment liquid internally) ), 44 ... Solution, B, C ... Metal-containing wastewater treatment system, T ... Direction (one direction, waste flow direction)

Claims (6)

A method for treating metal-containing wastewater for removing metal from metal-containing wastewater.
The raw water supply process for supplying the metal-containing wastewater into the annular treatment flow path, and
A circulation step in which the metal-containing wastewater supplied into the treatment flow path is circulated by flowing in a predetermined direction in the treatment flow path.
A pH adjusting step of adding a pH adjusting agent to the metal-containing wastewater in the treatment flow path to adjust the pH of the metal-containing wastewater, and
A coagulant addition step of adding a coagulant to the metal-containing wastewater whose pH has been adjusted, and
A floc collection step of collecting flocs aggregated and settled by the flocculant, and a floc collection step.
And downstream of the circulating water the flock is collected in the processing passage, the supernatant water the flock is discharged out of the processing flow paths are collected, and the electrolyzed electrolytic process, and
A method for treating metal-containing wastewater, which comprises. A method for treating metal-containing wastewater for removing metal from metal-containing wastewater.
The raw water supply process for supplying the metal-containing wastewater into the annular treatment flow path, and
A circulation step in which the metal-containing wastewater supplied into the treatment flow path is circulated by flowing in a predetermined direction in the treatment flow path.
A pH adjusting step of adding a pH adjusting agent to the metal-containing wastewater in the treatment flow path to adjust the pH of the metal-containing wastewater, and
A coagulant addition step of adding a coagulant to the metal-containing wastewater whose pH has been adjusted, and
A floc collection step of collecting flocs aggregated and settled by the flocculant, and a floc collection step.
A second pH adjusting step of adding a pH adjusting solution to the supernatant water in which the flocs are collected to adjust the pH of the supernatant water, and
An electrolysis step of electrolyzing the circulating water on the downstream side where the flocs are collected in the treatment flow path and the solution filled in the tank for preparing the pH adjusting liquid inside.
A method for treating metal-containing wastewater, which comprises. The method for treating metal-containing wastewater according to claim 2, wherein the content of the halogen compound in the pH adjusting solution is 0.2% by mass or less. A system for removing metal from metal-containing wastewater.
An annular treatment flow path for temporarily storing the metal-containing wastewater to be treated, and
A raw water supply unit that supplies the metal-containing wastewater to the inside of the treatment flow path,
A flow generating means for flowing and circulating the metal-containing wastewater inside the treatment flow path in a predetermined direction is provided.
In the treatment flow path, a pH adjusting unit for adjusting the pH of the metal-containing wastewater by adding a pH adjusting agent to the metal-containing wastewater, a coagulant adding unit for adding a coagulant to the metal-containing wastewater, and the coagulation. A floc collection section that collects flocs that have aggregated and settled due to the agent,
A pH adjustment tank that adjusts the pH of the supernatant water in which the flocs are collected, and
With
An electrolysis means having a cathode arranged on the downstream side of the floc collecting portion in the processing flow path, an anode arranged inside the pH adjusting tank, and a power source.
A metal-containing wastewater treatment system characterized by being further equipped with. A system for removing metal from metal-containing wastewater.
An annular treatment flow path for temporarily storing the metal-containing wastewater to be treated, and
A raw water supply unit that supplies the metal-containing wastewater to the inside of the treatment flow path,
A flow generating means for flowing and circulating the metal-containing wastewater inside the treatment flow path in a predetermined direction is provided.
In the treatment flow path, a pH adjusting unit for adjusting the pH of the metal-containing wastewater by adding a pH adjusting agent to the metal-containing wastewater, a coagulant adding unit for adding a coagulant to the metal-containing wastewater, and the agglomeration. A floc collection section that collects flocs that have aggregated and settled due to the agent,
A pH adjustment tank that adjusts the pH of the supernatant water in which the flocs are collected, and
A pH adjusting liquid preparation tank for preparing a pH adjusting liquid for adjusting the pH of the supernatant water, and
With
An electrolysis means having a cathode arranged on the downstream side of the floc collecting portion in the processing flow path, an anode arranged inside the pH adjusting liquid preparation tank, and a power source.
A metal-containing wastewater treatment system characterized by being further equipped with. The metal-containing wastewater treatment system according to claim 5, wherein the content of the halogen compound in the solution filled in the pH adjusting liquid preparation tank is 0.2% by mass or less.

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