JP2002307074A - Wastewater treatment method and wastewater treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wastewater treatment method and apparatus enabling high speed treatment while dealing with even load fluctuations by chemically treating wastewater with an inexpensive inorganic acid such as hydrochloric acid or inorganic alkali such as caustic soda without increasing the treatment amount of sludge by a flocculant or the like and capable of making a treatment apparatus compact. SOLUTION: The inorganic acid is added to a wastewater treatment liquid to adjust the pH of the liquid to 3 or less and polyvalent metal ions such as Fe<2+> , Fe<3+> , Al<3+> , Mg<2+> , Ca<2+> , Cu<2+> , Zn<2+> , Co<2+> are eluted from a mineral- containing substance contained in the wastewater treatment liquid and organic matter contained in the wastewater treatment liquid is flocculated by the flocculation action of polyvalent metal ions to be precipitated and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to livestock manure, human waste,
The present invention relates to a wastewater treatment method and apparatus for sewage, food processing waste liquid, factory waste liquid, and the like.

[0002]

2. Description of the Related Art From the viewpoint of environmental conservation, livestock manure, night soil,
The importance of technology for purifying wastewater such as sewage and factory wastewater is increasing. At present, as a technology for purifying wastewater, a flocculation method in which a flocculant is added, and a dissolved substance is flocculated and precipitated, and an activated sludge method using microorganisms are mainly used.

[0003]

As the flocculant, aluminum sulfate (sulfuric acid band), polyaluminum chloride (PAC), ferric chloride and the like are generally used. If the lysate throughput is large,
The amount of the coagulant to be added is about the amount of the dissolved material to be treated or about several times, which is not economical. Further, the added flocculant is discharged as sludge together with the flocculated sediment. Therefore, when the amount of the flocculant added increases, the final sludge treatment amount increases accordingly.

[0004] Further, the activated sludge treatment by microorganisms depends on the treatment capacity of microorganisms, so that a longer residence time is inevitably required, and the treatment equipment must be larger. In addition, since the microorganisms are microorganisms, there is a problem that if the operation is stopped for a long period of time, it takes time to start up.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to increase the sludge treatment amount without using a coagulant or the like, and to chemically treat the sludge with an inorganic acid such as hydrochloric acid or an inorganic alkali such as caustic soda. It is an object of the present invention to provide a wastewater treatment method and a wastewater treatment device that can perform high-speed treatment corresponding to load fluctuations and can also reduce the size of a treatment device.

[0006]

The mineral components contained in the wastewater treatment liquid in the form of oxides, hydroxides, etc. are converted to Fe ²⁺ , Fe ³⁺ ,
^{Al 3+, Mg 2+, Ca 2} +, Cu 2+, Mn 2+,
It is known that they elute as polyvalent metal ions such as Zn ²⁺ and Co ²⁺ . As an example, see p. 69-79 described in Fifth Edition Electrochemical Handbook (published by Maruzen Co., Ltd.).
An excerpt from the H-potential diagram is shown in FIG. (A), (b), (c), and (d) of FIG.
FIG. 4 is a pH-potential diagram showing the correlation between H and H, taking the oxidation-reduction potential E / V on the vertical axis. Dashed line A is a hydrogen electrode reaction at in FIG. _{^{(2H + + 2e - = H}} 2) E of _h = _-0.059pH (2
5 ° C.), and the dashed line B indicates the oxygen electrode (O ₂ +4).
H ⁺ + 4e ⁻ = 2H ₂ O) E _O2 = 1.23-0.059 pH (2
5 ° C.). These (a) to (d) of FIG.
As is clear from FIG.
It is located in the area sandwiched between. As the pH of the solution becomes acidic, ^ions such as Fe ²⁺ , Fe ³⁺ , and Cu ²⁺ begin to elute, and Al ³⁺ ions elute when the pH becomes 2.57 or less.

On the other hand, FIG. 2 (a) shows that the present inventors confirmed the effect of the present invention by examining the liquid obtained by gradually adding hydrochloric acid to the waste liquid obtained by methane fermentation of actual livestock manure. 5 is a photograph taken to enable visual observation of the bleached state.
The decolorized state of the waste liquid in the test tube (pH adjusting liquid) when the amount of added hydrochloric acid was increased from left to right in the figure is shown together with the measured pH value. In addition, each pH-adjusted liquid was filtered through a 0.2-micron filter, and the amount of organic carbon and the amount of protein (mg /
l) and the results of component analysis for each of them are shown in FIG.
Shown in As can be seen from these charts, the pH of the solution
It was found that both the organic carbon and the protein in the solution coagulated and precipitated together as the acid content decreased and the acid shifted. Especially p
It was found that when the H value was 2.80 or less, the aggregation of organic substances was accelerated, the waste liquid was decolorized, and the supernatant liquid became transparent.

[0008] The analysis of organic carbon and protein was carried out at 0.1.
It is clear from FIG. 2 (a) that since the filtration is performed using a solution after 2 micron filtration, even a suspended suspension of a larger size can be effectively precipitated by aggregating action. That is, only by manipulating the pH of the processing solution, it is possible to remove suspended solids and organic substances, and to perform decolorization accompanying the removal.
In addition, it can be seen that the amount of organic carbon is decreasing with the decrease in pH, but in particular, when the pH reaches about 2.8, decolorization progresses remarkably. On the other hand, it has been found that setting the pH to less than 3 (pH <3) is an effective means.

[0009] Such an effect is that the mineral-containing substance originally contained in the processing solution is dissolved as polyvalent metal ions due to the acidification of the processing solution, and this has been effective for the coagulation effect. It is presumed that there is.

As a result of further studies on the above-mentioned phenomenon, the present inventors have found that the mineral-containing substance in the wastewater treatment liquid is added to a low-priced inorganic acid such as hydrochloric acid to a pH of less than 3 (pH <3).
It is only necessary to prepare an acidic solution of 3), and if it is dissolved as a polyvalent metal ion, without adding another flocculant,
It has been found that dissolved organic carbon can be removed by coagulation and precipitation. Based on such findings, the present inventors have completed the present invention.

The livestock manure and the methane fermentation waste liquid which are the subject of the present invention contain mineral feed as livestock feed to the livestock, so that it can be said that the manure contains a large amount of mineral components. . In addition, since aluminum sulfate (sulfuric acid band) is used at the time of papermaking, human urine containing a large amount of toilet paper contains Al as a mineral source. In addition, a large amount of Al and Ti are present in the sewage, and it can be said that the wastewater treatment target of the present invention has a large amount of mineral-containing substances.

A feature of the present invention is that F was originally contained in the wastewater treatment liquid.
e, Al, Mg, Ca, Cu, Mn, Zn, Co, etc. are included as elements such as minerals that do not contribute anything as a coagulant as they are, using inexpensive inorganic acids such as hydrochloric acid. An object of the present invention is to remove organic substances and the like by acidifying a solution to elute it as ions and to function as a flocculant.

In the wastewater treatment method according to the present invention, an inorganic acid is added to the wastewater treatment solution to adjust the pH to 3 or less, and Fe ²⁺ , F is removed from the mineral-containing substances contained in the wastewater treatment solution.
e ³⁺ , Al ³⁺ , Mg ²⁺ , Ca ²⁺ , Cu ²⁺ , Mn
^{It is characterized in that} polyvalent metal ions such as ²⁺ , Zn ²⁺ , Co ²⁺ are eluted, and the organic substances contained in the wastewater treatment liquid are coagulated and precipitated and removed by the coagulation action of the polyvalent metal ions.

The wastewater treatment apparatus according to the present invention comprises a phosphating tank containing hydrated titanium oxide fine particles, and a wastewater treatment solution containing phosphate ions introduced into the phosphating tank. The pH is adjusted to pH 6 or less by adding an inorganic acid,
Means for specifically adsorbing phosphate ions contained in the wastewater treatment liquid to the hydrated titanium oxide fine particles to remove precipitates, and removing the precipitated aggregates of the hydrated titanium oxide fine particles adsorbed phosphate ions to the phosphorus A means for extracting phosphate ions from the acid treatment tank to a phosphate ion concentration tank, adding an inorganic alkali in the phosphate ion concentration tank to adjust the pH to 10 or more, and desorbing phosphate ions into the supernatant, and hydration desorbing and precipitating phosphoric acid. Means for circulating and reusing the titanium oxide fine particles as the phosphoric acid adsorbent in the phosphating tank, and, when the amount of the hydrated titanium oxide fine particles being circulated is insufficient, electrolyzing the fine particles into the phosphating tank. A plurality of titanium electrodes provided in the phosphating tank and a DC current is supplied to the titanium electrodes to replenish or add hydrated titanium oxide to the phosphating tank. Characterized by comprising a source and a.

The present inventors have proposed that mineral-containing substances contained in a wastewater treatment liquid are converted into an easily manipulable inorganic acid solution such as hydrochloric acid with respect to livestock manure and its methane fermentation waste liquid and night soil. By adding and acidifying, it is ionized and eluted and effectively acts as a flocculant, and it is confirmed by experiments that organic substances and the like contained in the wastewater treatment liquid are effectively flocculated and precipitated. The present invention provides a wastewater treatment apparatus which can chemically treat the wastewater at a high speed.

In the process of neutralizing a wastewater treatment liquid in an acidic state, a cheap slaked lime or quick lime,
Alternatively, by neutralizing with an alkaline solution containing calcium carbonate, phosphate ions contained in the wastewater treatment are precipitated and removed as insoluble calcium phosphate salts.

As means for concentrating and recovering precious phosphate ions not merely by precipitating and removing precious phosphate ions, water produced by eluting fine particles of hydrated titanium oxide, particularly titanium or a titanium alloy electrode, by electrolysis is used. Fine titanium oxide particles have been found to have excellent phosphate ion adsorption performance in acidic solutions, and can be efficiently desorbed by pH control of the solution. Phosphate ions are removed from the wastewater treatment liquid by adsorption and precipitation of phosphate ions, and the hydrated titanium oxide fine particles that have adsorbed phosphoric acid are desorbed by converting them into an alkaline solution. An object of the present invention is to provide a wastewater treatment apparatus incorporating a function of economically removing phosphate ions from a wastewater treatment liquid by utilizing the same.

FIG. 3 shows the pH value of the processing solution on the horizontal axis and the P elution rate (phosphate ion elution rate) (mass%) on the vertical axis, and shows hydrated titanium oxide fine particles adsorbing phosphate ions. FIG. 9 is a characteristic diagram in which results of an experiment and investigation of an elution rate by alkali with respect to are plotted. As is clear from the figure, the P elution rate is almost zero below pH 6, but
Since the P elution rate sharply increases between pH 8 and 10, it was confirmed that the hydrated titanium oxide fine particles had the effect of adsorbing and removing phosphate ions from the alkaline solution. In addition, pH12
In a strong alkaline solution, the P elution rate was 90% or more, and it was confirmed that most of the phosphoric acid could be eliminated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIG. The wastewater treatment apparatus according to the first embodiment includes two tanks 2 and 11 as treatment tanks. The acid precipitation tank 2 on the upstream side communicates with the two supply lines 1 and 10 and the two discharge lines 4 and 6, respectively, and controls the pH of the processing solution by adding an inorganic acid to the processing solution to make it acidic. It removes organic matter by precipitation. The neutralization tank 11 on the downstream side communicates with the two supply lines 4 and 18 and the two discharge lines 12 and 14, respectively, and controls the pH of the processing solution by adding an alkali to make the processing solution almost neutral. It is to meet emission standards.

In the acidic sedimentation tank 2, one supply line 1 is connected to a drainage source (not shown) so that waste liquid such as human waste is supplied to the tank 2 via the line 1 as a treatment liquid. . Also, the supply line 1 on the other side
Numeral 0 communicates with the upper acid solution tank 3 via a valve 9. Hydrochloric acid is stored in the acid solution tank 3 as an inorganic acid.

A discharge line 4 on one side of the acid precipitation tank 2
Is connected to the peripheral portion of the acidic precipitation tank 2 and the neutralization tank 11 in order to discharge the supernatant liquid in the tank 2 to the neutralization tank 11 on the downstream side. A pH controller 5 is provided at an appropriate position of the discharge line 4. pH controller 5
Measures the pH of the supernatant discharged from the tank 2 and further transmits a pH controller signal 8 to the acid supply line 10.
To the drive circuit of the valve 9 for feedback control of the valve opening. Thereby, the supernatant liquid in the tank 2 is adjusted to a pH of less than 3.

The discharge line 6 on the other side of the acid sedimentation tank 2 communicates with the bottom of the acid sedimentation tank 2 and a sludge treatment tank (not shown) in order to extract the settled sludge from the tank 2. The discharge line 6 is provided with a valve 7 that is opened and closed by a controller (not shown).

In the neutralization tank 11, one of the supply lines 4 communicates with the above-mentioned acid precipitation tank 2,
The supernatant liquid is introduced into the neutralization tank 11 through the line 4. The other supply line 18 communicates with an upper alkaline solution tank 16 via a valve 17. The alkali solution tank 16 stores a sodium hydroxide solution as an inorganic alkali.

The discharge line 12 on one side of the neutralization tank 11
In order to discharge the supernatant liquid in the tank 11 out of the system,
It communicates with the side periphery of the neutralization tank 11. A second pH controller 13 is provided at an appropriate position in the discharge line 12. The pH controller 13 measures the pH of the supernatant discharged from the tank 11 and sends a pH controller signal 19 to the drive circuit of the valve 17 of the alkali supply line 18 to feedback-control the valve opening. It has become. As a result, the supernatant liquid in the tank 11 is adjusted to a range of pH 5.8 to 8.6, which is a discharge standard.

The other discharge line 14 communicates with the bottom of the neutralization tank 11 and a sludge treatment tank (not shown) for extracting the settled sludge from the tank 11. The discharge line 14 is provided with a valve 15 that is opened and closed by a controller (not shown).

Next, a description will be given of a case where waste liquid is subjected to wastewater treatment using the above apparatus. A waste liquid as a processing liquid is supplied to an acidic precipitation tank 2 from a waste liquid storage facility (not shown).
The processing solution is animal manure, night soil, sewage,
It consists of food processing waste liquid, factory waste liquid, etc., and its pH is in the range of about 5-10. The pH of the treatment liquid in the acid precipitation tank 2 is measured by the pH controller 5, and based on the measurement result, the pH controller signal 8 is sent to the drive circuit of the valve 9 to adjust the valve opening, and the predetermined amount is adjusted. Hydrochloric acid (or hydrochloric acid solution) is supplied from the acid solution tank 3 into the acidic precipitation tank 2 via the supply line 10. Thereby, the pH of the treatment liquid in the acidic precipitation tank 2 is controlled. The acid precipitation tank 2
The set pH of the solution inside is usually less than pH 3 (pH
The operation is controlled so as to be <3).

In the acidic sedimentation tank 2, a hydrochloric acid supply line 1 is removed from the mineral-containing substance contained in the treatment liquid.
Polyvalent metal ions are eluted by hydrochloric acid supplied from 0,
Coagulates and separates fine suspended solids and organic components. Then, the settled sludge accumulated at the bottom of the acidic settling tank 2 is discharged to the discharge line 6 by opening the valve 7, and further carried from the discharge line 6 to the next sludge treatment facility for treatment. In addition, although the sludge treatment differs for each target treatment liquid such as effective use as compost after dehydration treatment or incineration disposal, the illustration of the equipment is omitted in the present embodiment.

On the other hand, the supernatant in the acid precipitation tank 2
Neutralization tank 11 via acid precipitation tank discharge line 4
Led to. In the neutralization tank 11, the pH of the processing solution is measured by the pH controller 13, and a pH controller signal 19 is sent to the drive circuit of the valve 17 of the alkali supply line 18 to feedback-control the valve opening. The supernatant liquid in the neutralization tank 11 is subjected to a neutralization treatment so as to fall within the range of pH 5.8 to 8.6 defined by the discharge standard, and is discharged from the neutralization tank discharge line 12. The sludge accumulated at the bottom of the neutralization tank 11 is transported from the neutralization tank sludge extraction line 14 via a valve 15 to the next sludge treatment facility, where it is subjected to final treatment.

With respect to the wastewater treatment liquid containing phosphate ions, slaked lime, quick lime, or calcium carbonate is contained in the alkaline solution tank 16 so that phosphate ions and calcium An insoluble calcium phosphate salt is generated by the ions, and can be removed by precipitation.

The hydrochloric acid in the acid solution tank 3 and the caustic soda in the alkali solution tank 16 are periodically replenished and operated.

The apparatus of the present embodiment makes it possible to effectively utilize minerals contained in the treatment liquid as a coagulant by acid treatment, thereby removing organic substances without increasing the amount of sludge by adding a coagulant or the like. Can be made possible.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. The reference numerals common to the apparatus of the present embodiment and the apparatus of the first embodiment have substantially the same function. In this embodiment, the acid precipitation tank 2 of the first embodiment is replaced with an acid mixing tank 20.
And the sedimentation tank 21, the supply amount of hydrochloric acid to the acid mixing tank 20 is optimized, the polyvalent metal ions are eluted by sufficient stirring and mixing, and the precipitation time in the sedimentation tank 21 is sufficiently ensured. In this way, the efficiency of removing and coagulating and precipitating organic substances is enhanced. That is, the wastewater treatment apparatus according to the second embodiment has three tanks 20, 21 and
And an acid mixing tank 20 dedicated to the stirring and mixing process.
Is provided with a sedimentation tank 21 exclusively for the sedimentation treatment.

The screw of the stirrer 25 is charged in the acid mixing tank 20 on the upstream side, and the solution is stirred and mixed. The acid mixing tank 20 communicates with two supply lines 1 and 10 and one discharge line 4 respectively. These lines 1, 4 and 10 are substantially the same as those in the first embodiment, and the pH of the solution in the acid mixing tank 20 is adjusted to less than 3 by the pH controller 5 of the discharge line 4. It has become.

The intermediate sedimentation tank 21 communicates with one supply line 4 and two discharge lines 23 and 24, respectively, and temporarily stores an acidic pH-controlled processing solution to thereby remove organic matter in the processing solution. Is precipitated and removed. By providing such a dedicated sedimentation tank 21, the efficiency of removing and coagulating and sedimenting organic substances is further improved.

The neutralization tank 11 on the downstream side communicates with the two supply lines 24 and 18 and the two discharge lines 12 and 14, respectively, and adds alkali to make the processing liquid substantially neutral.
By controlling the H, the processing liquid is adapted to the discharge standard.

Next, a description will be given of a case where waste liquid is subjected to wastewater treatment using the above-described apparatus. A waste liquid as a processing liquid is supplied to an acid mixing tank 20 from a waste liquid storage facility (not shown). The processing liquid is composed of livestock excreta mainly composed of organic matter, night soil, sewage, food processing waste liquid, factory waste liquid, etc., and its pH is about 5 to 5.
It is in the range of 10. PH of treatment liquid in acid mixing tank 20
Is measured by the pH controller 5, and based on the measurement result, p
The H regulator signal 8 is sent to the drive circuit of the valve 9 to adjust the valve opening, and a predetermined amount of hydrochloric acid (or hydrochloric acid solution) is supplied from the acid solution tank 3 into the acid mixing tank 2 via the supply line 10. . Thereby, the pH of the treatment liquid in the acid mixing tank 20 is controlled. In addition, the set pH of the processing solution in the acid mixing tank 20
Controls the operation so that it is usually less than pH 3 (pH <3). Further, the polyvalent metal ions contained in the treatment liquid are eluted, sufficiently stirred and mixed by the stirrer 25, and then sent to the precipitation tank 21.

In the sedimentation tank 21, the pH adjusting solution is kept for a certain period to coagulate and precipitate organic substances. The sludge accumulated at the bottom of the settling tank 21 is extracted from the discharge line 23 by opening the valve E22, and is sent to the next sludge treatment step to be treated.

On the other hand, the supernatant of the sedimentation tank 21 is sent to the neutralization tank 11 via the discharge line 24, neutralized by adding an appropriate amount of sodium hydroxide solution as in the first embodiment, and discharged. After meeting the standards, it is discharged out of the system.

According to the apparatus of the present embodiment, since the sedimentation time is sufficiently ensured in the dedicated sedimentation tank 21, the efficiency of removing and coagulating sedimentation of organic substances is further improved.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. Note that reference numerals common to the apparatus of the present embodiment and the apparatuses of the first and second embodiments have substantially the same function. In the present embodiment, instead of making the entire treatment liquid acidic, only the sludge containing a large amount of minerals effectively acting on coagulation is subjected to acid treatment, and polyvalent metal ions are extracted and supplied to the treatment liquid 1. Thus, wastewater treatment by removing coagulated sediment is performed more economically and efficiently. That is, the wastewater treatment apparatus of the third embodiment has three tanks 30 and 3 as treatment tanks.
3 and 11 are provided, and a sedimentation tank 30 is provided exclusively for sedimentation treatment, and a sludge acidification treatment tank 33 is provided exclusively for sludge acidity treatment.

The settling tank 30 has two supply lines 1, 36
And the two discharge lines 32 and 37, respectively, to precipitate and remove the organic sludge by retaining the treatment liquid for a long time. The sludge acid treatment tank 33 has two supply lines 32, 10 and two discharge lines 35, 36.
And an inorganic acid is added to the mixture to control the pH of the treatment liquid to be acidic, thereby precipitating and removing organic substances in the treatment liquid. Settling tank 30 and sludge acid treatment tank 3
3 are communicated with each other by a line 32,
The sludge settled at the bottom of the sludge is supplied to the upper part of the sludge acid treatment tank 33 through the line 32. By providing such a dedicated sludge acid treatment tank 33, the efficiency of removing and coagulating and sedimenting organic substances is greatly improved. The discharge line 37 of the sedimentation tank 30 communicates with the upper part of the neutralization tank 11 so that the supernatant liquid in the sedimentation tank 30 is directly sent to the neutralization tank 11.

The pH controller 5 is provided at an appropriate position of the discharge line 36 of the sludge acid treatment tank 33. pH controller 5
Measures the pH of the supernatant discharged from the tank 33 and further transmits a pH controller signal 8 to the acid supply line 1.
The control signal is sent to the drive circuit of the zero valve 9 to feedback-control the valve opening. This makes tank 3
The supernatant in No. 3 is adjusted to a pH of less than 3.

A second pH controller 13 is provided at an appropriate position of the discharge line 12 of the neutralization tank 11. This pH controller 13 controls the pH of the supernatant discharged from the tank 11.
Is measured, and a pH controller signal 19 is sent to a drive circuit of the valve 17 of the alkali supply line 18 to feedback-control the valve opening.
As a result, the supernatant liquid in the tank 11 is p
H5.8 to 8.6.

Next, a description will be given of a case where waste liquid is subjected to wastewater treatment using the above apparatus. A waste liquid as a processing liquid is supplied to the settling tank 30 from a waste liquid storage facility (not shown). The treatment liquid is composed of livestock excreta, organic waste, manure, sewage, food processing waste liquid, factory waste liquid, etc., and its pH is about 5-1.
It is in the range of 0. The waste liquid is set in the sedimentation tank 30 for a long time.
For example, the sludge is allowed to stay for one hour to settle sludge at the bottom of the settling tank 30. The valve 31 is opened, and the sludge settled at the bottom is discharged and supplied to the sludge acid treatment tank 33. Next, the pH of the treatment liquid in the sludge acid treatment tank 33 is measured by the pH adjuster 5, and based on the measurement result, the pH adjuster signal 8 is sent to the drive circuit of the valve 9 to adjust the valve opening. A predetermined amount of hydrochloric acid (or hydrochloric acid solution) is supplied from the acid solution tank 3 into the sludge acid treatment tank 33 via the supply line 10. As a result, the treatment liquid in the sludge acid treatment tank 33 is adjusted to a pH of less than 3 (pH 3
Control so as to be <3), and extract polyvalent metal ions from the mineral-containing substance in the sludge.

The valve 34 is opened, and the sludge accumulated at the bottom of the acidic sludge treatment tank 33 is extracted from the discharge line 35 and discharged to the next sludge treatment step.

On the other hand, the supernatant liquid containing a large amount of polyvalent metal ions in the sludge acid treatment tank 33 is returned to the former settling tank 30 via the sludge acid treatment tank supernatant line 36. In the sedimentation tank 30, the organic component in the treatment liquid is coagulated and precipitated by the polyvalent metal ions supplied from the supernatant line 36 and purified.

The supernatant liquid of the precipitation tank 30 is sent to the neutralization tank 11 via the discharge line 37, and neutralized by adding an appropriate amount of a sodium hydroxide solution as in the first and second embodiments. Is discharged out of the system after meeting emission standards.

According to the present embodiment, the amount of hydrochloric acid used can be reduced by extracting the polyvalent metal ions necessary for coagulation and sedimentation from the sludge as compared with the case where the entire treatment liquid is subjected to acidic treatment. The amount of use of an inorganic alkali solution such as caustic soda in the sum treatment can be reduced.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIG. The reference numerals common to the apparatus of the present embodiment and the apparatuses of the first to third embodiments have substantially the same function. The configuration up to the neutralization tank discharge line 12 of the present embodiment is substantially the same as that of the device of the third embodiment (FIG. 6). In the apparatus of the present embodiment, the ion exchange tank 40 is further provided downstream of the neutralization tank 11 so that the mineral component in the processing solution is maximally confined in the system and is effectively used. For this purpose, the polyhydric metal ions contained therein are adsorbed by passing through the ion exchange tank 40 before discharging the treatment liquid after coagulation and sedimentation out of the system. The ion exchange tank 40 is filled with a cation exchange resin or an ore having ion exchange properties (maltite, biotite, Io stone, etc.). Further, the polyvalent metal ions adsorbed in the ion exchange tank 40 are recovered in the acidic backwash water tank 52 and circulated to the precipitation tank 30, and the polyvalent metal ions are circulated and used more effectively. It causes coagulation and sedimentation.

The ion exchange tank 40 has two supply lines 1
2, 49 and two discharge lines 45, 46, respectively. One supply line 12 supplies the supernatant of the sedimentation tank 11 to the lower part of the ion exchange tank 40, and the other supply line 49 supplies backwash water from the backwash water tank 52 to the ion exchange tank 40. It is supplied to the upper part. Further, one of the discharge lines 45 is connected to the ion exchange tank 40.
The processing liquid is withdrawn from the lower part of the tank and returned to the sedimentation tank 30 on the most upstream side, and the discharge line 46 on the other side discharges the processing liquid satisfying the discharge standard to the outside of the system and reversely flows through the branch line 47 A part of the processing liquid is returned to the washing tank 52. Switching between a branch line 47 branched from the discharge line 46 and a discharge line communicating outside the system is performed by valves 42 and 48 and a downstream valve (not shown).

The backwash water tank 52 has two supply lines 4
7, 50 and one discharge line 49 respectively. The one supply line 47 corresponds to the above-mentioned branch line, and supplies the processing liquid extracted from the upper part of the ion exchange tank 40 to the backwash water tank 52. The other supply line 50 supplies hydrochloric acid as an inorganic acid to the backwash water tank 52. The supply line 50 is branched from the line 10 directly communicating with the acid solution tank 3, and a valve 51 is provided at an appropriate position. This valve 5
1 is a pH controller 5 attached to the backwash water tank 52.
3, the opening and closing operation is controlled. pH
The controller 53 detects the pH of the processing liquid in the backwash water tank 52 and adjusts the opening of the valve 51 based on the detection result.

The discharge line 49 of the backwash water tank 52 is
The H-controlled processing liquid is sent to the upper part of the ion exchange tank 40. A valve 43 whose opening and closing operation is controlled by a controller (not shown) is provided at an appropriate position of the discharge line 49 so that supply and stop of the pH control treatment liquid from the backwash water tank 52 to the ion exchange tank 40 are performed. Has become.

Next, a description will be given of a case where the waste liquid is drained using the above-described apparatus. A waste liquid as a processing liquid is supplied to the settling tank 30 from a waste liquid storage facility (not shown). The treatment liquid is composed of livestock excreta, organic waste, manure, sewage, food processing waste liquid, factory waste liquid, etc., and its pH is about 5-1.
It is in the range of 0. The waste liquid is set in the sedimentation tank 30 for a long time.
For example, the sludge is allowed to stay for one hour to settle sludge at the bottom of the settling tank 30. The valve 31 is opened, and the sludge settled at the bottom is discharged and supplied to the sludge acid treatment tank 33. Next, the pH of the treatment liquid in the sludge acid treatment tank 33 is measured by the pH adjuster 5, and based on the measurement result, the pH adjuster signal 8 is sent to the drive circuit of the valve 9 to adjust the valve opening. A predetermined amount of hydrochloric acid (or hydrochloric acid solution) is supplied from the acid solution tank 3 into the sludge acid treatment tank 33 via the supply line 10. As a result, the treatment liquid in the sludge acid treatment tank 33 is adjusted to a pH of less than 3 (pH 3
Control so as to be <3), and extract polyvalent metal ions from the mineral-containing substance in the sludge.

The valve 34 is opened, and the sludge accumulated at the bottom of the acidic sludge treatment tank 33 is extracted from the discharge line 35 and discharged to the next sludge treatment step.

On the other hand, the supernatant liquid containing a large amount of polyvalent metal ions in the sludge acid treatment tank 33 is returned to the former settling tank 30 via the sludge acid treatment tank supernatant line 36. In the sedimentation tank 30, the organic component in the treatment liquid is coagulated and precipitated by the polyvalent metal ions supplied from the supernatant line 36 and purified.

The supernatant of the settling tank 30 is supplied to a discharge line 37.
And neutralized by adding an appropriate amount of a sodium hydroxide solution. Then, after satisfying the discharge standard in the neutralization tank 11, the sludge settled at the bottom is discharged out of the system through the discharge line 14.

The valves 41 and 42 are opened, and the neutralization tank 11 is opened.
Is passed through the ion exchange tank 40. The supernatant of the neutralization tank 11 enters the ion exchange tank 40 from the lower part via the discharge line 12 and enters the ion exchange tank 4.
After the polyvalent metal ion contained within 0 is adsorbed and removed,
It is discharged from the upper part of the ion exchange tank 40 to the outside of the system via the discharge line 46.

On the other hand, the valve 48 is opened and the branch line 47 is opened.
And a part of the liquid in the discharge line 46 is supplied to the backwash water tank 52. Next, the pH adjuster 53 opens the valve 51,
A predetermined amount of hydrochloric acid is supplied from the acid solution tank 3 via the branch line 50. That is, the pH controller 53 detects the pH of the treatment liquid in the backwash water tank 52, adjusts the opening of the valve 51 based on the detection result, and adds a predetermined amount of hydrochloric acid to the backwash water tank 52. I do. This allows the backwash water tank 52
The pH of the processing solution is controlled within the range of pH 4-5.

The inlet valve 4 attached to the ion exchange tank 40
1 and the outlet valve 42 are closed at regular intervals and the valves 43 and 44 are opened, and the acidic liquid supply line 4 is closed.
The acidic solution is supplied as backwash water from 9 and the ion exchange tank 4
Ion exchange between polyvalent metal ions and hydrogen ions in 0,
The polyvalent metal ions are recovered and supplied to the settling tank 30 via the backwash water discharge line 45. By this treatment, the sedimentation tank 30
In this method, polyvalent metal ions in the system are confined and utilized to the maximum extent, and coagulation and precipitation are removed.

According to the present embodiment, the provision of the ion exchange tank 40 functions not only as an ion exchange but also as a filtration tank, so that it is possible to further purify waste water.

(Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIG. The reference numerals common to the apparatus of the present embodiment and the apparatuses of the first to fourth embodiments have substantially the same function. The upstream side of the sedimentation tank 21 of this embodiment and the downstream side of the neutralization tank 11 have substantially the same configuration as the apparatus of the second embodiment (FIG. 5). In the apparatus of the present embodiment, the phosphoric acid treatment tank 60 and the adsorption / regeneration tank 65 are inserted between the sedimentation tank 21 and the neutralization tank 11 so that the acidic wastewater subjected to the coagulation and sedimentation treatment is neutralized before being neutralized. Instead of simply precipitating and removing the valuable phosphate ions contained, they are collected and reused.

The fact that phosphate ions are adsorbed on hydrated titanium oxide is known, for example, from Taguchi, Kusumi, Mitani, and Mashima; The Chemical Society of Japan, 1991, (5), pp. 623 to 629. Et al. Have further studied the adsorption characteristics of phosphate ions. As a result, the hydrated titanium oxide fine particles obtained by electrolyzing and dissolving the titanium electrode specifically adsorb phosphate ions under acidic conditions (pH <6). Alkali (pH
> 8), a new finding of excellent desorption performance. Based on such knowledge, the present inventors have developed the device of the present embodiment.

The phosphating tank 60 is provided with a pair of titanium electrodes 7.
3 and are connected to two supply lines 24 and 67 and two discharge lines 62 and 74, respectively. The one supply line 24 supplies the supernatant liquid from the precipitation tank 21 to the upper part of the phosphating tank 60. The other supply line 67 supplies the sediment from the adsorption / regeneration tank 65 to the upper part of the phosphating tank 60. The one discharge line 74 sends the supernatant from the phosphating tank 60 to the upper part of the neutralization tank 11. The discharge line 62 on the other side is for sending the precipitate from the phosphating tank 60 to the upper part of the adsorption / regeneration tank 65.

The adsorption / regeneration tank 65 has two supply lines 1
8, 62 and two discharge lines 67, 68, respectively. The one supply line 18 is for adding and supplying the alkaline solution from the alkaline solution tank 16 to the adsorption / regeneration tank 65. The other supply line 62 supplies the sediment from the phosphating tank 60 to the adsorption / regeneration tank 65. The one discharge line 67 is for sending the precipitate from the adsorption / regeneration tank 65 to the phosphating tank 60. The discharge line 68 on the other side discharges the processing liquid out of the system. The discharge line 68 has a pH controller 70
Is provided. The pH controller 70 includes an adsorption / regeneration tank 65.
When the measured pH does not satisfy the discharge standard, the valve 69 is opened and a predetermined amount of sodium hydroxide solution is supplied from the alkaline solution tank 16 to the adsorption / regeneration tank 65.

The titanium electrode 73 in the phosphating tank 60 is connected to a DC switching power supply 63 via a lead wire 64.
It is dissolved by energization and replenishes hydrated titanium oxide fine particles. The energization of the titanium electrode 73 is a DC energization, but the polarity is switched about every one hour so that the titanium electrode 73 is used while preventing adhesion to the electrode surface. Titanium electrode 73
In addition to the method of replenishing hydrated titanium oxide fine particles using, a replenishment tank storing hydrated titanium oxide fine particles is separately prepared, and an appropriate amount of hydrated titanium oxide fine particles is replenished from the replenishment tank to the phosphate ion treatment tank. It is good also as a method.

It is desirable to use industrial pure metal titanium for the titanium electrode 73, but a titanium alloy containing a small amount of additional element may be used. The size of the titanium electrode 73 can be variously changed according to the volume and the processing amount of the phosphating tank 60, and the total surface area is 10 cm ² per liter of the processing tank.
It is desirable to make it larger. If the surface area of the titanium electrode 73 is smaller than 10 cm ² per liter of the treatment tank, the number of the hydrated titanium oxide fine particles is insufficient, and the phosphate ions cannot be sufficiently adsorbed. The titanium electrode 73
It is preferable to supply power so that the current density is 50 to 100 mA / cm ² .

The hydrated titanium oxide described in the present invention is:
Titanium hydroxide (Ti (OH) ₄ ), which is produced first when titanium is used as an anode and eluted by electrolysis, repeatedly undergoes dehydration condensation to form Ti (titanium) and O (oxygen) as shown in FIG.
The specific adsorption of phosphate ions is mainly due to the hydroxyl groups (OH ⁻ ) bonded to the outermost Ti atoms and the monovalent phosphate ions (H ₂ PO ₄ ^−). Or by ion exchange with KHPO ₄ ⁻ ). Therefore, by adjusting the solution pH, it is possible to move the equilibrium state to adsorb or desorb phosphate ions.

The present inventors have determined that K ₂ HPO ₄ : 0.45 [g / L] as a test solution (2.8 L) and P: 8 in terms of phosphorus.
Direct current flow (16 V, 1 A) using a solution of 0 [mg / l] and NaCl: 10 [g / L], using titanium as the anode and platinum as the cathode.
Hydrated titanium oxide was eluted from the titanium electrode, and the change in the concentration of phosphate ions in the solution was measured by an ion chromatography method. As a result, when the power was supplied at 25 W, the phosphorus concentration (phosphate ion concentration) was 2.7 ( mg / l), and it was confirmed that the removal rate reached 97%.

Next, the desorption characteristics of phosphate ions were measured by titrating a sodium hydroxide solution to the hydrated titanium oxide fine particles to which phosphate ions had been adsorbed to obtain an alkaline solution. The result is shown in FIG.

FIG. 3 is a plot of measured values with the horizontal axis representing pH and the vertical axis representing P elution rate (phosphate ion elution rate) (%). As is clear from the figure, it was confirmed that most of the phosphoric acid can be eliminated by setting the pH to about 12. From this fact, by using hydrated titanium oxide fine particles eluted from the titanium electrode for adsorption and desorption of phosphate ions, adsorption with an acidic solution and desorption with an alkaline solution are possible. It was confirmed that ion concentration was possible. FIG. 8 shows a fifth embodiment of the present invention in which this operation is implemented as a device.

Next, a description will be given of a case where waste liquid is drained using the above-described apparatus. A waste liquid as a processing liquid is supplied to an acid mixing tank 20 from a waste liquid storage facility (not shown). The processing liquid is composed of livestock excreta mainly composed of organic matter, night soil, sewage, food processing waste liquid, factory waste liquid, etc., and its pH is about 5 to 5.
It is in the range of 10. The organic liquid is removed in the precipitation tank 21, and the treatment liquid in the precipitation tank discharge line 24 in an acidic state is:
It is sent to the phosphating tank 60. In the phosphating tank 60, phosphate ions are adsorbed and precipitated by contact with a solution containing hydrated titanium oxide fine particles supplied from the adsorbent circulation line 67, and accumulate at the bottom. The fine particles of hydrated titanium oxide adsorbing the phosphate ions collected at the bottom of the phosphating tank 60 are sent from the phosphoric acid sludge extraction line 62 to the adsorbent regeneration tank 65 via the valve 61. The pH of the solution in the adsorbent regeneration tank 65 is measured by a pH controller 70, and p
The opening degree of the valve 69 is adjusted via the H regulator signal 71, and an inorganic alkali solution such as caustic soda is supplied from the alkali solution tank 16 to maintain the alkali (pH 10 to 12) for desorbing phosphate ions. Is done. The fine particles of hydrated titanium oxide adsorbing phosphate ions supplied from the phosphate sludge extraction line 62 desorb phosphate ions and precipitate at the bottom due to the alkali state in the adsorbent regeneration tank 65. The hydrated titanium oxide fine particles collected at the bottom of the adsorbent regeneration tank 65 are passed through a valve 66 to an adsorbent circulation line 67.
Is recycled to the phosphate ion treatment tank 60 as a phosphate ion adsorbent.

The phosphating tank 6 from which phosphate ions have been removed.
The supernatant in 0 is sent to the neutralization tank 11 via the phosphating tank discharge line 74, and is discharged out of the system after the neutralization treatment as in the first and second embodiments.

The supernatant liquid containing a large amount of phosphate ions in the adsorbent regenerating tank 65 is discharged from the adsorbent regenerating tank discharge line 68 via the valve 72, and is effectively used as phosphoric acid resources.

When it is necessary to remove nitrogen such as ammonia from the processing solution, an organic ammonia, phosphorus, ammonia, etc. can be comprehensively added by adding an existing ammonia stripping apparatus to the apparatus of the present invention. Can be removed.

[0076]

According to the present invention, the load variation can be reduced by chemically treating the sludge with an inorganic acid such as hydrochloric acid or an inorganic alkali such as caustic soda without increasing the sludge treatment amount with a coagulant or the like. The corresponding high-speed wastewater treatment becomes possible.

Further, according to the present invention, the organic substance and phosphorus contained in the waste liquid can be quickly precipitated by using a treatment tank having a simple structure, so that the apparatus is downsized.

[Brief description of the drawings]

FIG. 1 (a) is a pH potential diagram of an Fe-based hydroxide, and (b)
Is the pH potential diagram of the Fe-based oxide, (c) is the pH potential diagram of the Al-based oxide, and (d) is the p potential diagram of the Cu-based oxide and hydroxide.
H potential diagram.

FIG. 2 (a) is a photograph taken so that the decolorized state of a methane fermentation liquid obtained by gradually adding hydrochloric acid to the methane fermentation liquid can be visually observed. FIG. 2 (b) is a methane fermentation liquid in a liquid decolorization observation experiment. 4 is a table showing the results of component analysis of the pH adjusting solution of FIG.

FIG. 3 is a characteristic diagram showing a phosphorus elution rate of various pH solutions (alkaline solutions) with respect to hydrated titanium oxide fine particles having phosphate ions adsorbed thereon.

FIG. 4 is a configuration block diagram schematically showing a wastewater treatment device according to the first embodiment of the present invention.

FIG. 5 is a configuration block diagram schematically showing a wastewater treatment device according to a second embodiment of the present invention.

FIG. 6 is a configuration block diagram schematically showing a wastewater treatment device according to a third embodiment of the present invention.

FIG. 7 is a configuration block diagram schematically showing a wastewater treatment device according to a fourth embodiment of the present invention.

FIG. 8 is a configuration block diagram schematically showing a wastewater treatment device according to a fifth embodiment of the present invention.

FIG. 9 is a structural diagram of hydrated titanium oxide.

[Explanation of symbols]

1: Treatment liquid supply line, 2: Acid precipitation tank, 3: Acid solution tank, 4: Acid precipitation tank discharge line (supernatant discharge line), 5: pH controller A, 6: Acid precipitation tank sludge extraction line (sludge) 7: Valve A, 8: pH controller A signal, 9: Control valve B, 10: Hydrochloric acid supply line, 11: Neutralization tank, 12: Neutralization tank discharge line (supernatant discharge line), 13 ... pH controller B, 14 ... neutralization tank sludge extraction line (sludge discharge line), 15 ... valve C, 16 ... alkaline solution tank, 17 ... valve D, 18 ... alkaline solution supply line, 19 ... pH controller B signal , 20: Acid mixing tank, 21: Settling tank A, 22: Valve E, 23: Settling tank A sludge extraction line (sludge discharge line), 24: Settling tank A discharge line (supernatant) 25 ... Agitator, 30 ... Sedimentation tank B, 31 ... Valve F, 32 ... Sedimentation tank B, 33 ... Sludge acid treatment tank, 34 ... Valve G, 35 ... Sludge acid treatment tank withdrawal line (sludge discharge line) 36, sludge acid treatment tank supernatant line (supernatant discharge line), 37 ... sedimentation tank B, 40 ... ion exchange tank, 41 ... valve H, 42 ... valve I, 43 ... valve J, 44 ... valve K, 45 ... Backwash water discharge line, 46 ... ion exchange tank discharge line, 47 ... ion exchange tank discharge branch line, 48 ... valve L, 49 ... acid solution supply line, 50 ... acid solution branch line, 51 ... valve M, 52 ... reverse Washing tank, 53: pH controller C, 60: Phosphate treatment tank, 61: Valve N, 62: Phosphate sludge extraction line (sludge discharge line), 63: DC switching power supply, 64: Lee Line 65: Adsorbent regeneration tank 66: Valve O 67: Adsorbent circulation line (sludge discharge line) 68: Adsorbent regeneration tank discharge line (supernatant discharge line) 69: Valve P 70: pH adjustment Device D, 71: pH controller D signal, 72: Valve Q, 73: Titanium electrode, 74: Phosphate treatment tank discharge line (supernatant liquid discharge line).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C02F 1/46 C02F 1/46 Z 4D061 1/58 1/58 S 11/14 11/14 Z F term ( 4D015 BA03 BA04 BA10 BA19 BB05 CA01 CA03 CA04 CA12 CA18 DA02 DA12 DA19 DA22 DA28 DA30 DC02 EA13 EA32 FA11 FA22 4D024 AA04 AB12 BA14 BC01 DA10 DB09 DB19 DB20 DB21 4D025 AA09 AB05 BA02 BA08 DA02 DA06 DA10 4D038 BB A08 4D059 AA01 BF12 DA01 DA03 DA04 DA05 DA08 DA15 DA21 DA22 4D061 DA08 DB09 EA02 EB01 EB04 EB14 EB30 FA06 FA08 FA11 FA14

Claims (7)

[Claims] We claim: 1. adding an inorganic acid to the waste water treatment was brought to pH3 or less, ^Fe 2+ minerals containing substances contained in the wastewater treatment ^{liquid, Fe 3+, Al 3+, Mg} 2 +, Ca
^Polyvalent metal ions such as ²⁺ , Cu ²⁺ , Mn ²⁺ , Zn ²⁺ , and Co ²⁺ are eluted, and organic substances contained in the wastewater treatment liquid are coagulated and precipitated and removed by the coagulation action of the polyvalent metal ions. And wastewater treatment method. 2. A coagulated sediment is extracted from the wastewater treatment liquid,
An inorganic acid is added to the coagulated sediment to adjust the pH to 3 or less, and the mineral-containing substance contained in the coagulated sediment contains Fe.
²⁺ , Fe ³⁺ , Al ³⁺ , Mg ²⁺ , Ca ²⁺ , Cu
^Polyvalent metal ions such as ²⁺ , Mn ²⁺ , Zn ²⁺ , and Co ²⁺ are eluted, and the supernatant is added to the wastewater treatment liquid to coagulate and remove organic substances contained in the wastewater treatment liquid. Wastewater treatment method characterized by the above-mentioned. 3. An organic alkali solution is further added to the wastewater treatment liquid from which organic substances have been removed by precipitation to adjust the pH to a range of 5.8 to 8.6, which is a discharge standard, and then discharged. Further, an alkaline solution containing slaked lime, quicklime, and calcium carbonate is added, and insoluble calcium phosphate is generated and precipitated by the phosphate ions in the wastewater treatment solution and the calcium ions in the added alkaline solution, and the phosphate ions are subjected to wastewater treatment. The method according to claim 1, further comprising removing the solution from the liquid, adjusting the pH to a range of 5.8 to 8.6 as a discharge standard, and discharging the solution. 4. A wastewater treatment solution containing phosphate ions is introduced into a phosphating tank containing hydrated titanium oxide fine particles, and the pH of the phosphating tank is adjusted to pH 6 or less by adding an inorganic acid such as hydrochloric acid. (A) specifically adsorbing phosphate ions contained in the wastewater treatment liquid to the hydrated titanium oxide fine particles to remove precipitates, and precipitating the hydrated titanium oxide fine particles adsorbing phosphate ions. Step (b) of extracting the aggregates from the phosphating tank into a phosphate ion concentrating tank and adding an inorganic alkali such as caustic soda to adjust the pH to 10 or more in the phosphate ion concentrating tank to desorb phosphate ions into the supernatant. (C) circulating and recycling the hydrated titanium oxide fine particles from which phosphoric acid has been desorbed and precipitated as the phosphoric acid adsorbent in the phosphating tank; In the case of shortage, in the phosphating tank, a titanium electrode, and a power supply for supplying an electric current to the titanium electrode are installed, and the phosphating tank is replenished by electrolysis or supplied to the phosphating tank. (D) adding a hydrated titanium oxide, and by concentrating phosphate ions contained in the aqueous solution in the phosphate ion concentration tank through the above steps (a) to (d). Wastewater treatment method, wherein recovery and reuse of phosphate ions are facilitated. 5. The wastewater treatment liquid from which organic substances have been precipitated and removed by the treatment method according to claim 1 or 2 is guided to a phosphating tank containing hydrated titanium oxide fine particles, and the wastewater treatment is performed. A step of specifically adsorbing phosphate ions contained in the liquid to the hydrated titanium oxide fine particles and removing the precipitates, and extracting an aggregate of the hydrated titanium oxide fine particles adsorbing the phosphate ions from the phosphoric acid treatment tank Adding an inorganic alkali such as caustic soda to adjust the pH to 10 or more to desorb and precipitate phosphate ions; and dissolving and precipitating phosphoric acid, the hydrated titanium oxide fine particles are treated with phosphoric acid as a phosphoric acid adsorbent. A step of circulating and recycling the tank, a titanium electrode, and a power supply for supplying a current to the titanium electrode are installed in the phosphating tank, and the amount of the hydrated titanium oxide fine particles circulated and used is reduced. 3. The method according to claim 1, further comprising, when added, a step of replenishing the phosphating tank by electrolysis or a step of adding hydrated titanium oxide to the phosphating tank. The method according to any one of the above. 6. A wastewater treatment liquid neutralized by the treatment method according to claim 3 or a cation exchange resin or an ore having an ion exchange function (maleite, black (Mica, Io stone, etc.) by passing through an ion exchange tank filled with the treated wastewater treatment liquid to remove polyvalent metal ions contained in the treated wastewater by ion exchange action, and then discharge The ion exchange tank is periodically backwashed with an inorganic acid solution such as hydrochloric acid, and exchanges and recovers the adsorbed polyvalent metal ions with hydrogen ions. A process in which polyvalent metal ions are confined in the system as much as possible and effectively utilized to enhance the effect of coagulation and sedimentation of organic substances by adding to the wastewater treatment liquid. Described in any one of Law. 7. A phosphating tank containing hydrated titanium oxide fine particles, and a wastewater treatment liquid containing phosphate ions is introduced into the phosphating tank, and the pH of the phosphating tank is adjusted by adding an inorganic acid. pH 6
Means for adjusting the following, specifically adsorbing phosphate ions contained in the wastewater treatment liquid to the hydrated titanium oxide fine particles and removing precipitates, and precipitation of the hydrated titanium oxide fine particles adsorbing phosphate ions. Means for extracting the aggregates from the phosphating tank into a phosphate ion concentration tank, adding an inorganic alkali in the phosphate ion concentration tank to adjust the pH to 10 or more, and desorbing phosphate ions into the supernatant; Means for circulating the separated precipitated hydrated titanium oxide fine particles as a phosphoric acid adsorbent in the phosphoric acid treatment tank and reusing the same; and when the amount of circulated hydrated titanium oxide fine particles is insufficient, electrodissolution. Replenish in the phosphating tank, or
In order to add hydrated titanium oxide to the phosphating tank,
A wastewater treatment apparatus comprising: a plurality of titanium electrodes provided in the phosphoric acid treatment tank; and a power supply for supplying a direct current to the titanium electrodes.