JP2018183754A - Method for treating metal-containing wastewater and treatment system for metal containing wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an amount of acid used to adjust pH of alkaline agent or treated water within a range of wastewater standard value, in a method for treating metal-containing wastewater.SOLUTION: A method for treating metal containing wastewater of the present invention includes: a raw water supplying step of supplying metal-containing wastewater into an annular treatment flow path 2; a circulation step of flowing and circulating wastewater 1 supplied into the treatment flow path 2 in a T direction in the treatment flow path 2; a pH adjusting step of adding a pH adjusting agent 5 to the wastewater 1 in the treatment flow path 2 to adjust pH of the wastewater 1; a coagulant adding step of adding coagulant 7 to the wastewater 1 whose pH has been adjusted; a floc collection step of collecting a floc which has aggregated and settled by the coagulant 7; and an electrolysis step of electrolyzing a downstream side circulating water 29 in which the floc is collected, and a supernatant water 17 in which the floc is collected in the treatment flow path 2.SELECTED DRAWING: Figure 1

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 sometimes simply referred to as “treatment method”), for example, metal ions dissolved in wastewater are converted into metal hydroxides or metal sulfides. There are a method of removing insoluble compounds such as, a method of removing metal ions dissolved in waste water as a metal chelate, and the like.

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

  As a method for increasing the floc removal efficiency and reducing the size of the sedimentation tank, a method for increasing the effective treatment area by installing an inclined plate (for example, see Patent Document 1 and Patent Document 2), A method for increasing the sedimentation rate of flocs by applying various flocculants (see, for example, Patent Document 3 and Patent Document 4) has been proposed and put into practical use.

JP 2001-327981 A JP 2002-136808 A JP 2011-031229 A Japanese Patent Laying-Open No. 2006-026871

However, in the method of increasing the floc removal efficiency by using the inclined plate as described above, particularly when floc having a low sedimentation speed is removed, the processing amount and the installation area are restricted, and the removal rate is 100% ( It becomes difficult to achieve a high removal rate of about 100%.
Also, in the method of increasing the floc sedimentation rate by applying various flocculants, there is a limit to growing large flocs by devising flocculants, and the processing cost is reduced by using special flocculants. It will increase.

  Based on the above circumstances, recently, a treatment method in which a pH adjustment tank (that is, an alkali treatment tank), a flocculant stirring tank, and a precipitation tank are used as one tank has been studied. In this treatment method, (1) it is not always necessary to remove all flocs (that is, the removal rate does not have to reach 100%), and (2) flocs circulating inside the tank are made of metal water. Since it becomes a nucleus when it is deposited as an oxide, a floc with high precipitation performance is generated, (3) the amount of alkaline agent added to the waste water can be reduced, (4) a pump connecting each tank, The effect that piping is unnecessary is acquired. However, in the above-described treatment method, although the effect described in the above (3) can be obtained, a large amount of acid for adjusting the pH of the alkaline agent and the treated water within the range of the drainage standard value is required. The problem that remained.

  This invention is made | formed in view of the said situation, Use of the acid (henceforth only an "acid") for adjusting the pH of an alkaline agent and treated water in the range of a wastewater reference value Disclosed is a metal-containing wastewater treatment method and a metal-containing wastewater treatment system capable of reducing 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, wherein the raw water supply supplies the metal-containing wastewater into an annular treatment channel. A step of circulating the metal-containing wastewater supplied into the processing channel in a predetermined direction and circulating the metal-containing wastewater in the processing channel; and a pH adjusting agent for the metal-containing wastewater in the processing channel. Adding, adjusting the pH of the metal-containing wastewater, adjusting the pH, adding a flocculant to the pH-adjusted metal-containing wastewater, and collecting flocs aggregated and settled by the flocculant A floc collecting step, and an electrolysis step for electrolyzing the downstream circulating water from which the floc has been collected and the supernatant water from which the floc has been collected in the processing flow path. It is characterized by.

  According to the above-described configuration, in the electrolysis step, the agent for adjusting the pH of the supernatant water (that is, the acid) is obtained by electrolyzing the circulating water and the supernatant water that have been subjected to the pH treatment in the pH adjustment step. ) Is not necessary. In addition, an alkali agent added to the metal-containing wastewater (ie, circulating water) in the circulation step by generating hydroxide ions corresponding to the acid used to adjust the pH of the supernatant water on the cathode side ( The amount of the pH adjusting agent can be reduced. Furthermore, accumulation of the salt (sodium ion in the case of sodium hydroxide) paired with the hydroxide ions and hydrogen ions described above 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, wherein raw water supply supplies the metal-containing wastewater into an annular treatment channel. A step of circulating the metal-containing wastewater supplied into the processing channel in a predetermined direction and circulating the metal-containing wastewater in the processing channel; and a pH adjusting agent for the metal-containing wastewater in the processing channel. Adding, adjusting the pH of the metal-containing wastewater, adjusting the pH, adding a flocculant to the pH-adjusted metal-containing wastewater, and collecting flocs aggregated and settled by the flocculant A floc collecting step, a second pH adjusting step of adjusting the pH of the supernatant water by adding a pH adjusting liquid to the supernatant water from which the floc has been collected, and the floc collecting in the processing channel. Collected downstream side Characterized in that it comprises circulating water and the electrically decomposing electrolytic process a solution inside is filled in a bath to create the pH adjusted solution, a.
In the method for treating metal-containing wastewater according to claim 3, in the above-described method for treating metal-containing wastewater, the content of the halogen compound in the pH adjusting liquid is preferably 0.2% by mass or less.

According to the above-described configuration, in the electrolysis step, for example, acidic water is obtained by electrolyzing the circulating water that has been subjected to pH treatment in the pH adjustment step and the solution that is filled in the preparation tank of the pH adjustment solution. The pH of the supernatant water is adjusted so as to satisfy the drainage standard using this acidic water, and the final treated water can be obtained. Moreover, the usage-amount of an acid can be restrained similarly to the processing method of the above-mentioned metal containing waste_water | drain.
Furthermore, acidic water can be produced | generated smoothly because content of the halogen compound in pH adjustment liquid is as small as 0.2 mass% or less.

  The metal-containing wastewater treatment system according to claim 4 is a system for removing metal from the metal-containing wastewater, and an annular treatment channel for temporarily storing the metal-containing wastewater to be treated; A raw water supply unit that supplies the metal-containing wastewater to the inside of the treatment channel, and a flow generation means for circulating the metal-containing wastewater inside the treatment channel in a predetermined direction, and A pH adjusting unit that adjusts the pH of the metal-containing wastewater by adding a pH adjuster to the metal-containing wastewater, a flocculant addition unit that adds a flocculant to the metal-containing wastewater, and the aggregation A floc collector that collects flocs aggregated and settled by the agent and a pH adjustment tank that adjusts the pH of the supernatant water from which the flocs have been collected, and the floc collector in the processing channel Downstream of Characterized in that it further comprises a electrolysis unit, a having arranged cathode and an anode and a power source disposed in the interior of the pH adjusting tank.

  According to the above-described 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 the pH adjustment step, by the electrolysis unit. Further, an alkali agent added to the metal-containing wastewater (that is, circulating water) in the treatment channel 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) is suppressed. Furthermore, accumulation of the salt (sodium ion in the case of sodium hydroxide) paired with the hydroxide ions and hydrogen ions is suppressed.

The metal-containing wastewater treatment system according to claim 5 is a system for removing metal from the metal-containing wastewater, and an annular treatment channel for temporarily storing the metal-containing wastewater to be treated; A raw water supply unit that supplies the metal-containing wastewater to the inside of the treatment channel, and a flow generation means for circulating the metal-containing wastewater inside the treatment channel in a predetermined direction, and A pH adjusting unit that adjusts the pH of the metal-containing wastewater by adding a pH adjuster to the metal-containing wastewater, a flocculant addition unit that adds a flocculant to the metal-containing wastewater, and the aggregation A floc collecting part for collecting flocs aggregated and settled by the agent, a pH adjusting tank for adjusting the pH of the supernatant water in which the flocs are collected, and a pH adjusting liquid for adjusting the pH of the supernatant water create H adjustment liquid preparation tank, and the electrolysis which has the cathode arrange | positioned in the downstream of the said floc collection part in the said process flow path, the anode arrange | positioned inside the said pH adjustment liquid preparation tank, and a power supply And a section.
In the metal-containing wastewater treatment system according to claim 6, it is preferable that the content of the halogen compound in the solution filled in the pH adjusting liquid preparation tank is 0.2% by mass or less.

According to the above-described configuration, in the electrolysis section, for example, acidic water is prepared by electrolyzing the circulating water and the pH adjusting liquid that have been subjected to pH treatment in advance in the pH adjusting step, and using this acidic water, The pH of the supernatant water is adjusted so as to satisfy the drainage standard, and final treated water is obtained. Moreover, the usage-amount of an acid is suppressed similarly to the processing system of the above-mentioned metal containing waste_water | drain.
Moreover, acidic water is produced | generated smoothly because the inside of a pH adjustment liquid preparation tank is satisfy | filled with the solution with little content of a halogen compound.

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

It is a figure of the processing system of the metal containing waste_water | drain of 1st embodiment to which this invention is applied, Comprising: An upper stage is a top view and a lower stage is a side view. It is a figure of the processing system of the metal containing waste_water | drain of 2nd embodiment to which this invention is applied, Comprising: An upper stage is a top view and a lower stage is a side view.

  Hereinafter, an embodiment of a method for treating metal-containing wastewater to which the present invention is applied will be described. Note that the drawings used in the following description are schematic, and the ratios of length, width, and thickness are not necessarily the same as actual ones, and can be changed as appropriate.

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

  As shown in FIG. 1, the metal-containing wastewater treatment system B of the first embodiment has an annular treatment channel 2 that temporarily stores the wastewater 1 to be treated, and a metal-containing wastewater inside the treatment channel 2. A raw water supply unit 3 for supplying 1a, a flow generating means 4 for circulating the waste water 1 inside the processing channel 2 in the T direction (one direction), and a circulation whose pH is adjusted in the processing channel 2 Electrolysis means 20 for electrolyzing water 29 and treated water (supernatant water) taken out from treated channel 2 is provided.

  The treatment channel 2 includes a pH adjuster 6 that adjusts the pH of the wastewater 1 by adding a pH adjuster 5 to the wastewater 1, a flocculant adder 8 that adds a flocculant 7 to the wastewater 1, and a flocculant 7. And a flock collecting section 9 for collecting the flocs that have aggregated and settled.

  In addition, the processing system B includes a flock collecting unit 10 for discharging the flocs collected by the flock collecting unit 9 from the flock collecting unit 9 to the outside of the processing flow path 2 and collecting the flocs, and the flocs sinking. A water collecting trough 11 for taking the supernatant water of the waste water 1 and discharging it to the outside of the processing flow path 2 and a rectifying means 12 for adjusting the flow of the waste water 1 are provided.

  The flow generating means 4 is for creating a flow in the T direction of the drainage 1 inside the annular processing channel 2 and circulating the drainage 1. The flow generating means 4 includes a shaft portion 4a that is driven to rotate around an axis, and a plurality of rotating plates 4b that extend in the radial direction 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 pushes the drainage 1 in the T direction sequentially, thereby creating a flow in the T direction and, consequently, a circulating flow. Yes.

  The flocculant adding unit 8 is provided between the pH adjusting unit 6 and the flow generating unit 4 of the processing flow channel 2. The flocculant addition unit 8 adds the flocculant 7 such as an anionic polymer flocculant to the drainage water 1 whose pH is adjusted by the pH adjustment unit 6 to aggregate and grow the hydroxide floc. belongs to. The aggregating agent adding section 8 is provided with a stirring means 13 for mixing and stirring the added aggregating agent 7 and the drainage 1.

  The flock collecting section 9 is provided on the downstream side in the T direction from the flow generating means 4. The floc collecting part 9 is for collecting flocs that grow by adding the flocculant 7 in the flocculant adding part 8 and deposit on the bottom surface 2a of the processing flow channel 2. Further, the floc collecting portion 9 is a floc collecting concave portion that is gradually inclined downward as the bottom surface 2a of the processing flow channel 2 is directed from the upstream side toward the downstream side, and is gradually inclined upward toward the downstream side from the lowest portion 2b. 14 is provided.

  The flock collecting unit 10 collects the flocks collected by the flock collecting unit 9 and accumulated in the lowest part 2b (the flock collecting concave portion 14) of the flock collecting unit 9 to the outside of the processing flow path 2. It is for recovery. The flock collecting unit 10 includes, for example, a collection pipe (not shown) connected to a flock collecting port that opens at the bottom surface of the lowest part 2b of the flock collecting unit 9, a pump for pulling out the flock from the processing channel 2 through the collection pipe, and the like. Recovery drive means (not shown).

  The water collection trough 11 is provided, for example, on the downstream side of the drainage 1 in the T direction from the flock collecting unit 9. The water collection trough 11 is for taking the supernatant water of the drainage 1 after the floc has settled and discharging it to the outside of the processing flow path 2. In addition, the position of the water collection trough 11 will not be specifically limited if the supernatant water of the waste_water | drain 1 can be taken and discharged | emitted out 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 flock collecting section 9. The rectifying means 12 includes, for example, a plurality of rectifying plates arranged in parallel with a predetermined interval.

  In the processing system B, a flow in the T direction is created with respect to the waste water 1 in the processing flow path 2 by the flow generating means 4, and the waste water 1 circulates in the annular processing 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 through the treatment flow path 2 by the pH adjusting unit 6 and stirred by the stirring means 13, whereby the pH of the waste water 1 is adjusted to a predetermined pH. When the pH is adjusted in this way, metal ions in the waste water 1 become hydroxides and flocs are formed.

  The drainage 1 containing flocs formed by the pH adjusting unit 6 reaches the flocculant adding unit 8, and the flocculant 7 is added and stirred and mixed by the stirring means 13, so that the fine flocs aggregate and become large. Grows into a flock.

  The waste water 1 that has passed through the flocculant addition unit 8 passes through the rectifying means 12 and the flow of the waste water 1 disturbed by the stirring means 13 is adjusted.

  Large flocs contained in the drainage 1 gradually settle due to their own weight and reach the bottom surface 2 a of the processing flow path 2. The bottom surface 2a of the processing channel 2 has a floc collecting portion 9 that gradually inclines downward toward the downstream side in the T direction and that gradually inclines upward toward the downstream side in the T direction after reaching the lowest portion 2b. Since the floc collecting concave portion 14 is provided, the floc that moves with the flow of the drainage 1 and reaches the bottom surface 2a of the processing flow path 2 is automatically collected and collected in the flock collecting concave portion 14 of the flock collecting portion 9. .

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

  The supernatant water (treated water that has been purified by floc sedimentation) 17 inside the treatment channel 2 is taken up by the water collecting trough 11 and discharged to the outside of the treatment channel 2. The pH of the supernatant water 17 is adjusted in a 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 disposed on the downstream side of the water collecting trough 11 in the T direction inside the processing flow channel 2. The anode 35 is disposed inside the pH adjustment tank 18.

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

  The method for treating metal-containing wastewater according to the first embodiment to which the present invention is applied (hereinafter, sometimes simply referred to as “treatment method”) is a treatment method using the treatment system B, and includes an annular treatment channel 2. A raw water supply step for supplying metal-containing wastewater to the inside, a circulation step for circulating the metal-containing wastewater supplied to the inside of the processing channel 2 in the T direction (predetermined direction) inside the processing channel 2, and A pH adjusting step for adjusting the pH of the metal-containing wastewater by adding the pH adjusting agent 5 to the metal-containing wastewater inside the processing flow path 2, and a flocculant addition for adding the flocculant 7 to the metal-containing wastewater whose pH has been adjusted A step, a floc collecting step for collecting flocs aggregated and settled by the flocculant 7, a downstream circulating water 29 in which the flocs are collected in the processing flow path 2, and a supernatant water in which the flocs are collected Electrolysis process for electrolyzing 17 , And a.

  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 subjected to the pH treatment in the pH adjustment step. Therefore, it is not necessary to use a large amount of medicine (ie, acid) for the purpose. Further, an alkali agent added to the metal-containing waste water (that is, the circulating water 29) in the circulation process by generating hydroxide ions corresponding to the acid used for adjusting the pH of the supernatant water at the cathode 33. The amount of (pH adjuster) can be reduced. Furthermore, accumulation of the salt (sodium ion in the case of sodium hydroxide) paired with the hydroxide ions and hydrogen ions described above can be suppressed.

  Further, in the metal-containing wastewater treatment system B of the first embodiment, flocs that could not be removed circulate automatically while being treated at each part a plurality of times. It is possible to grow and remove large flocs reliably in the circulation.

  Moreover, since it comprised so that a some process could be performed continuously within one system, the quantity of the pH adjuster 5 added to metal containing waste_water | drain can be reduced, and also each conventional process process is tied. Pumps and piping can be eliminated.

  Therefore, according to the metal-containing wastewater treatment system B of the first embodiment, it is possible to more effectively and economically settle and separate even a floc having a low sedimentation rate and reliably remove it.

(Second embodiment)
Next, a processing system and a processing method according to the second embodiment to which the present invention is applied will be described. Note that, among the components of the processing system of the second embodiment, the same components as those of the processing system B of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 2, in addition to the configuration of the processing system B of the first embodiment, the processing system C of the second embodiment creates a pH adjusting liquid 30 for adjusting the pH of the supernatant water 17 inside. A pH adjusting liquid preparation tank 40 is provided. Further, the anode 35 of the electrolysis means 20 is disposed inside the pH adjustment liquid preparation tank 40.

  In order to smoothly create acidic water as the pH adjusting liquid 30, the content of the halogen compound in the solution 44 filled in the pH adjusting liquid preparing tank 40 is 0% by mass or more and 0.2% by mass or less. Preferably there is. That is, it is preferable that the pH adjustment 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 according to the second embodiment to which the present invention is applied (hereinafter sometimes simply referred to as “treatment method”) is a treatment method using the treatment system C, and includes an annular treatment channel 2. A raw water supply step for supplying metal-containing wastewater to the inside, a circulation step for circulating the metal-containing wastewater supplied to the inside of the processing channel 2 in the T direction (predetermined direction) inside the processing channel 2, and A pH adjusting step for adjusting the pH of the metal-containing wastewater by adding the pH adjusting agent 5 to the metal-containing wastewater inside the processing flow path 2, and a flocculant addition for adding the flocculant 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 the pH adjusting liquid 30 to the supernatant water 17 in which the step, the flocs aggregated and settled by the flocculant 7 and collecting the flocs, and the flocs collected PH adjustment step and the inside of the processing channel 2 Oite flock is provided with an electric decomposing electrolysis step and circulating water 29 and solution 44 of the collected downstream.

Therefore, in the metal-containing wastewater treatment system C and the treatment method of the second embodiment, the circulating water 29 that has been subjected to the pH treatment in advance and the solution 44 that is filled in the pH adjusting solution preparation tank 40 are electrolyzed. Thus, for example, acidic water (functioning as a pH adjusting liquid 30) can be prepared, and the pH of the supernatant water 17 can be adjusted so as to satisfy the drainage standard using this acidic water, whereby the final treated water 19 can be obtained. Further, in the processing system C and the processing method, the amount of acid used can be suppressed as in the processing system B and the processing method of the first embodiment.
Furthermore, acidic water can be produced | generated smoothly because the pH adjustment liquid preparation tank 40 is filled with the solution 44 which does not contain a halogen element as mentioned above.
Such a treatment system C and treatment method are particularly useful for treatment of wastewater containing a large amount of salt such as oil-associated water from which oil has been removed.

  As mentioned above, although one Embodiment of the processing system of the metal containing waste_water | drain based on this invention was described, this invention is not limited to the above-mentioned one Embodiment, It can change suitably in the range which does not deviate from the meaning.

  For example, the arrangement and number of the water collecting troughs 11 may be devised, the flow rate of the drainage 1 may be reduced using the water collecting troughs 11, and the flocs settling may be promoted. That is, the arrangement and number of the water collecting troughs 11 may be determined so as to improve the efficiency of collecting the flocs in the flock collecting unit 9.

DESCRIPTION OF SYMBOLS 2 ... Processing flow path, 3 ... Raw water supply part, 4 ... Flow generation means, 5 ... pH adjuster, 6 ... pH adjuster, 7 ... Flocculant, 8 ... Flocculant addition part, 9 ... Flock collection part, 10 DESCRIPTION OF SYMBOLS Flock collection | recovery part, 17 ... Supernatant water, 18 ... pH adjustment tank, 19 ... Final process water, 29 ... Circulating water, 30 ... pH adjustment liquid, 40 ... pH adjustment liquid preparation tank (The tank which produces pH adjustment liquid inside ), 44 ... Solution, B, C ... Metal-containing wastewater treatment system, T ... direction (one direction, wastewater distribution direction)

Claims (6)

A method for treating metal-containing wastewater for removing metal from metal-containing wastewater,
Raw water supply step for supplying the metal-containing wastewater into the annular processing channel;
A circulation step of circulating the metal-containing wastewater supplied in the treatment flow path in a predetermined direction in the treatment flow path;
Adding a pH adjuster to the metal-containing wastewater in the treatment channel, and adjusting the pH of the metal-containing wastewater;
a flocculant addition step of adding a flocculant to the metal-containing wastewater whose pH is adjusted;
A flock collecting step of collecting flocks aggregated and settled by the flocculant;
An electrolysis step of electrolyzing the circulating water on the downstream side in which the floc is collected in the treatment flow path and the supernatant water in which the floc is collected;
A method for treating metal-containing wastewater, comprising: A method for treating metal-containing wastewater for removing metal from metal-containing wastewater,
Raw water supply step for supplying the metal-containing wastewater into the annular processing channel;
A circulation step of circulating the metal-containing wastewater supplied in the treatment flow path in a predetermined direction in the treatment flow path;
Adding a pH adjuster to the metal-containing wastewater in the treatment channel, and adjusting the pH of the metal-containing wastewater;
a flocculant addition step of adding a flocculant to the metal-containing wastewater whose pH is adjusted;
A flock collecting step of collecting flocks aggregated and settled by the flocculant;
A second pH adjusting step of adjusting the pH of the supernatant water by adding a pH adjusting solution to the supernatant water in which the floc is collected;
An electrolysis step of electrolyzing the downstream circulating water in which the floc is collected in the processing flow path and the solution filled in the tank for preparing the pH adjusting solution therein;
A method for treating metal-containing wastewater, comprising:   The method for treating metal-containing wastewater according to claim 2, wherein the content of the halogen compound in the pH adjusting liquid is 0.2% by mass or less. A system for removing metal from metal-containing wastewater,
An annular treatment channel for temporarily storing the metal-containing wastewater to be treated;
A raw water supply unit for supplying the metal-containing wastewater into the treatment channel;
A flow generating means for circulating the metal-containing waste water inside the processing flow channel in a predetermined direction, and
A pH adjusting unit that adjusts the pH of the metal-containing wastewater by adding a pH adjuster to the metal-containing wastewater, a flocculant addition unit that adds a flocculant to the metal-containing wastewater, and the aggregation A floc collecting part for collecting flocs aggregated and settled by the agent;
A pH adjusting tank for adjusting the pH of the supernatant water in which the floc is collected;
With
An electrolysis means having a cathode disposed on the downstream side of the floc collecting section in the processing flow path, an anode disposed in the pH adjustment tank, and a power source;
A metal-containing wastewater treatment system, further comprising: A system for removing metal from metal-containing wastewater,
An annular treatment channel for temporarily storing the metal-containing wastewater to be treated;
A raw water supply unit for supplying the metal-containing wastewater into the treatment channel;
A flow generating means for circulating the metal-containing waste water inside the processing flow channel in a predetermined direction, and
A pH adjusting unit that adjusts the pH of the metal-containing wastewater by adding a pH adjuster to the metal-containing wastewater, a flocculant addition unit that adds a flocculant to the metal-containing wastewater, and the aggregation A floc collecting part for collecting flocs aggregated and settled by the agent;
A pH adjusting tank for adjusting the pH of the supernatant water in which the floc is collected;
A pH adjusting solution creating tank for creating a pH adjusting solution for adjusting the pH of the supernatant water;
With
An electrolysis means having a cathode disposed on the downstream side of the floc collecting part in the processing flow path, an anode disposed in the pH adjusting liquid preparation tank, and a power source;
A metal-containing wastewater treatment system, further comprising:   6. 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 solution preparation tank is 0.2% by mass or less.

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