JP2023091343A - Method of treating wastewater including metal ions and ammonia, device of treating wastewater including metal ions and ammonia, and ammonia adsorption column - Google Patents

Abstract

To provide an easy and low-cost method of treating wastewater including metal ions and ammonia, capable of more surely treating metal ions.SOLUTION: The method of treating wastewater including metal ions and ammonia, comprises the steps of: bringing wastewater including metal ions and ammonia into contact with an ammonia adsorbent 24 to cause the ammonia adsorbent 24 to adsorb ammonia; subjecting the wastewater after adsorption of ammonia to the coagulation reaction to coagulate metal ions using a coagulation precipitation method; and applying solid-liquid separation treatment to the wastewater after the coagulation reaction.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a method for treating waste water containing metal ions and ammonia, a device for treating waste water containing metal ions and ammonia, and an ammonia adsorption tower.

Wastewater discharged from factories such as fertilizer factories, dye factories, semiconductor factories, and plating factories, as well as power plants, etc., is discharged into rivers, etc. after being properly treated in consideration of the environment. . For example, the wastewater discharged from the factories and power plants mentioned above contains metal ions such as light and heavy metals. In order to discharge waste water containing metal ions into rivers or the like, appropriate waste water treatment (for example, coagulation sedimentation method, etc.) is performed to reduce the concentration of metal ions in the waste water to a standard value or less.

The wastewater discharged from the factories and power plants described above often contains, for example, ammonia together with metal ions. Various treatment methods have been proposed as treatment methods for waste water containing metal ions and ammonia.

For example, Patent Literature 1 discloses a method of treating waste water containing metals and ammonia. The method for treating wastewater containing metals and ammonia disclosed in Patent Document 1 includes a treatment of contacting the wastewater with a chelate resin or an ion exchange resin, and then adjusting the pH to 8 to 12 to remove the precipitated metal hydroxide in a solid-liquid manner. A treatment of separation is performed, and then a treatment of contact with a noble metal-supported catalyst is performed in the coexistence of an oxygen-containing gas.

Patent Literature 2 discloses a physicochemical treatment method for nitrogen-containing waste water. In the physicochemical treatment method for nitrogen-containing wastewater disclosed in Patent Document 2, ammonia nitrogen-containing wastewater containing metal components is treated by a catalytic wet oxidation treatment method, or ammonia nitrogen-containing wastewater containing metal components is treated. This is a method of treatment by the ammonia stripping treatment method. In the treatment method disclosed in Patent Document 2, after adjusting the pH of the waste water to 9 to 12, the waste water is treated by passing it through a bed packed with cation exchange resin particles. Then, after the treatment of passing the waste water, the treatment by the catalytic wet oxidation treatment method is performed, or after passing the waste water, the treatment by the ammonia stripping treatment method is performed.

Japanese Patent Application Laid-Open No. 2001-009481 JP-A-2000-334451

According to the wastewater treatment technology disclosed in Patent Document 1, first, wastewater is brought into contact with a chelate resin or an ion exchange resin to remove metal ions that form complexes with ammonia. Then, by adjusting the pH to a specific range, metal ions in the waste water that have not been captured by the chelate resin or ion exchange resin are precipitated as metal hydroxides. Then, the metal ions are removed by solid-liquid separation of the deposited metal hydroxide. After removing metals from wastewater containing metals and ammonia, ammonia is oxidatively decomposed by bringing it into contact with a noble metal-supported catalyst in the coexistence of an oxygen-containing gas.

However, in the wastewater treatment technology disclosed in Patent Document 1, the chelate resin and the ion exchange resin are expensive, and it is necessary to select the chelate resin and the ion exchange resin for each metal component contained in the wastewater. Furthermore, the wastewater treatment technology disclosed in Patent Document 1 performs oxidative decomposition treatment of ammonia using a noble metal-supported catalyst, which tends to increase equipment costs.

According to the wastewater treatment technology disclosed in Patent Document 2, first, by adjusting the pH of wastewater to a specific range, metal components are precipitated as metal hydroxides and metal complexes. Then, by passing the waste water through the cation exchange resin, the precipitated metal hydroxide and metal complex are removed. Then, after the wastewater is passed through the cation exchange resin, ammonia nitrogen is removed by applying a catalytic wet oxidation treatment method or an ammonia stripping treatment method.

However, in the wastewater treatment technology disclosed in Patent Document 2, similarly to the wastewater treatment technology disclosed in Patent Document 1, the ammonia cation exchange resin is expensive. In addition, the ammonia stripping treatment method is not economical because the cost of the alkaline agent is high, and the re-adsorption and concentration treatment of ammonia is performed. Furthermore, the wastewater treatment technology disclosed in Patent Document 2 uses a catalytic wet oxidation treatment method or an ammonia stripping treatment method for ammonia, which tends to increase equipment costs.

In addition, the wastewater treatment technology disclosed in Patent Document 1 and Patent Document 2 is performed by adjusting the pH of wastewater containing metal ions as metal components and ammonia in the previous stage of ammonia treatment, thereby removing precipitated metal hydroxides. It is a technique to remove things in advance. In waste water in which metal ions and ammonia coexist, the metal ions form an ammine complex with ammonia. For this reason, in wastewater treatment in which metal ions and ammonia coexist, wastewater treatment methods in which metal components are treated by pH adjustment prior to ammonia treatment, as disclosed in Patent Documents 1 and 2, are The component removal efficiency was low, and the treatment method was not capable of reliably separating and treating metal components in the wastewater.

An object of the present invention is to provide a method for treating wastewater containing metal ions and ammonia that is simple, inexpensive, and more reliable in treating wastewater containing metal ions and ammonia. and a method for treating the waste water or an ammonia adsorption tower used in the apparatus for treating the waste water.

According to one aspect of the present invention, there is provided a method for treating wastewater containing metal ions and ammonia, wherein the treatment method includes bringing the wastewater containing the metal ions and the ammonia into contact with an ammonia adsorbent to adsorb the ammonia. a step of causing the ammonia to be adsorbed on the material, a step of subjecting the waste water after adsorbing the ammonia to aggregating reaction of the metal ions by a coagulation sedimentation method, and a solid-liquid separation process of the waste water after the aggregating reaction. A method for treating wastewater containing metal ions and ammonia is provided, comprising the steps of:

In the method for treating waste water containing metal ions and ammonia according to one aspect of the present invention, the ammonia adsorbent is preferably zeolite.

In the method for treating waste water containing metal ions and ammonia according to one aspect of the present invention, the coagulation-sedimentation method is preferably a hydroxide method.

In the method for treating wastewater containing metal ions and ammonia according to one aspect of the present invention, the aggregating step includes adding a pH adjuster to the wastewater after adsorbing the ammonia to adjust the pH to 9 or more and 12 or less. is adjusted to the range of , and the metal ions are subjected to the aggregation reaction by the aggregation-sedimentation method.

According to one aspect of the present invention, there is provided an apparatus for treating wastewater containing metal ions and ammonia, wherein the treatment apparatus brings the wastewater containing the metal ions and the ammonia into contact with an ammonia adsorbent to adsorb the ammonia. an ammonia adsorption tower in which the ammonia is adsorbed on the material; a coagulation reaction tank in which the wastewater after the ammonia has been adsorbed flowing from the ammonia adsorption tower undergoes a coagulation reaction of the metal ions by a coagulation sedimentation method; and the coagulation reaction tank. and a coagulation-sedimentation tank for solid-liquid separation of the coagulation-reacted waste water flowing in from the waste water treatment apparatus containing metal ions and ammonia.

According to one aspect of the present invention, ammonia used in the method for treating waste water containing metal ions and ammonia according to one aspect of the present invention, or the apparatus for treating waste water containing metal ions and ammonia according to one aspect of the present invention An ammonia adsorption tower is provided, wherein the ammonia adsorption tower is used to bring the waste water containing the metal ions and the ammonia into contact with the ammonia adsorbent.

In the ammonia adsorption tower according to one aspect of the present invention, the ammonia adsorption tower is attached to and detached from a route through which waste water containing the metal ions and the ammonia is fed and a route through which waste water after adsorbing the ammonia is fed. Preferably possible.

In the ammonia adsorption tower according to one aspect of the present invention, the ammonia adsorption tower is supplied with the ammonia adsorbent, an adsorbent-filled container containing the ammonia adsorbent, and waste water containing the metal ions and the ammonia. It is preferable to provide a supply port side connection member provided on the channel side, and an outlet side connection member provided on the side of the channel through which the waste water after adsorbing the ammonia is fed.

In the ammonia adsorption tower according to one aspect of the present invention, it is preferable that the ammonia adsorbent accommodated in the adsorbent packed container is replaceable.

According to the present invention, in the treatment of wastewater containing metal ions and ammonia, there is provided a method for treating wastewater containing metal ions and ammonia that is simple, inexpensive, and capable of more reliably treating metal ions. It is possible to provide a waste water treatment apparatus containing the waste water, and an ammonia adsorption tower used in the waste water treatment method or the waste water treatment apparatus.

It is a schematic block diagram which represents typically an example of the waste water treatment apparatus used for the conventional waste water treatment method. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows typically an example of the waste water treatment apparatus used for the waste water treatment method which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows typically an example of the ammonia adsorption tower used for the waste water treatment process which concerns on this invention. 4 is a graph showing the results of wastewater treatment (relationship between pH and zinc concentration in supernatant water) in Example 1 and Comparative Example 1. FIG. 10 is a graph showing the results of wastewater treatment (relationship between standing time and distance from liquid surface to sedimentation surface) in Example 2 and Comparative Example 2. FIG.

An example of preferred embodiments of the present invention will be described in detail below. The invention is not limited to the content of the embodiments.

[Wastewater treatment method and wastewater treatment equipment]
A treatment method, which is an example of a preferred embodiment of the present invention, comprises a step of contacting waste water containing metal ions and ammonia with an ammonia adsorbent to adsorb ammonia on the ammonia adsorbent (ammonia adsorption step); a step of causing metal ions to undergo aggregation reaction (aggregation reaction step) in the wastewater after the coagulation, and a step of solid-liquid separation treatment of the wastewater after the aggregation reaction (solid-liquid separation step). .

A treatment apparatus, which is an example of a preferred embodiment of the present invention, includes an ammonia adsorption tower in which waste water containing metal ions and ammonia is brought into contact with an ammonia adsorbent, and ammonia is adsorbed by the ammonia adsorbent; A coagulation-sedimentation tank in which the wastewater after adsorption of ammonia undergoes a coagulation reaction of metal ions by a coagulation-sedimentation method, and a coagulation-sedimentation tank in which the wastewater after the coagulation reaction flowing in from the coagulation-reaction tank undergoes solid-liquid separation. Prepare.

Conventional methods for removing metal ions in wastewater containing metal ions include the hydroxide method, sulfide method, substitution method, liquid chelate method, coagulation sedimentation method such as treatment with a heavy metal remover, and chelate Various treatment methods such as adsorption method with resin can be mentioned. Among these, the hydroxide method, which is easy to control and inexpensive, is generally applied to the treatment of waste water containing metal ions.

Wastewater treatment by the conventional hydroxide method is performed, for example, by the following steps. First, waste water containing metal ions is stored in a raw water tank or the like, or is directly sent to a flocculation reaction tank. Next, the wastewater sent to the flocculation reaction tank is added with an alkaline agent (eg, slaked lime) as a pH adjuster, and if necessary, a flocculant is also added and stirred. Waste water after stirring is sent to the coagulating sedimentation tank. In the coagulating sedimentation tank, the generated sludge is sedimented and solid-liquid separated into sludge and supernatant water. The sludge that settles at the bottom of the coagulating sedimentation tank is pulled out by a sludge pump or the like and disposed of at a final disposal site or the like. The solid-liquid separated waste water in the coagulating sedimentation tank is sent to a filter or the like. Flocs that have not settled in the coagulation sedimentation tank and suspended matter are removed by a filter or the like. Then, the treated water from which the flocs and suspended solids have been removed is discharged into a river or the like.

An example of a conventional waste water treatment method and waste water treatment apparatus will be described below with reference to FIG. In addition, in FIG. 1, some parts are enlarged or reduced for the sake of facilitating the explanation. As shown in FIG. 1, a conventional waste water treatment apparatus 1A includes a raw water tank 10A that stores waste water containing metal ions, and a coagulation reaction tank 30A that causes the waste water flowing in from the raw water tank 10A to undergo a coagulation reaction of metal ions by a coagulation sedimentation method. , a coagulation sedimentation tank 50A for solid-liquid separation of waste water flowing from the coagulation reaction tank 30A, and a filter 70A for filtering the waste water flowing from the coagulation sedimentation tank 50A.

The wastewater treatment process using the conventional wastewater treatment apparatus 1A is processed through the following steps. First, as waste water discharged from various factories or power plants, waste water containing metal ions (water to be treated) is sent to the raw water tank 10A. In the raw water tank 10A, raw water 12A, which is water to be treated as waste water containing metal ions, is temporarily stored. The raw water 12A stored in the raw water tank 10A is sent by the pump 11A through the pipeline 13A and flows into the aggregation reaction tank 30A. In the agglutination reaction tank 30A, a chemical solution 36A such as a pH adjuster is supplied from a tank 35A through a pipeline 37A by a pump (not shown). The aggregation reaction tank 30A is provided with a stirrer (not shown), and is stirred by the stirrer. The wastewater after stirring overflows as the coagulation reaction water 32A, is sent through the pipeline 33A, and flows into the coagulation sedimentation tank 50A. In the coagulation sedimentation tank 50A, the supplied coagulation reaction water 32A undergoes solid-liquid separation into coagulated sludge 54A and coagulation treated water 52A as supernatant water. The sludge 54A is drawn out from the coagulating sedimentation tank 50A by a pump (not shown). The coagulated water 52A is sent to the filter 70A through the pipeline 53A and filtered by the filter 70A. Then, the filtered treated water 72A is discharged to a river or the like as treated water.

By the way, when ammonia is contained together with metal ions in waste water, the metal ions form an ammine complex with ammonia. When metal ions are separated by the coagulation-sedimentation method, the flocculation and settling properties of metal ions tend to decrease due to the influence of ammine complexes present in the wastewater, and the efficiency of reducing the concentration of metal ions in the wastewater tends to decrease. There is Therefore, it takes a long time to reduce the metal ion concentration to the reference value or less, and there is a possibility that the metal ion concentration cannot be reduced to the reference value or less before being discharged.

For example, when treating wastewater containing ammonia together with metal ions in a wastewater treatment process using a conventional wastewater treatment apparatus 1A as shown in FIG. 1, the metal ions formed an ammine complex with ammonia. Coagulation sedimentation treatment is performed as it is. For example, when zinc ions are included as metal ions, the zinc ions are subjected to the coagulation sedimentation treatment while forming an ammine complex with ammonia. Therefore, as for the solubility of zinc, the ammine complex of zinc has higher solubility of zinc metal than simple zinc metal, and the pH range for removing zinc ions becomes narrower. Also, the settling rate of zinc hydroxide is reduced, increasing the residence time for processing.

In general, representative ammonia removal methods include, for example, biological nitrification and denitrification methods, ammonia stripping methods, chlorine oxidation methods, and catalytic cracking methods. In the coagulation-sedimentation method, as a measure for suppressing the inhibition of flocculation and sedimentation by an ammine complex of metal ions and ammonia, for example, before the coagulation-sedimentation treatment for separating metal ions, the representative ammonia It is conceivable to employ a removal method to remove the ammonia in advance.

The biological nitrification and denitrification method is a method of nitrifying ammonia in wastewater into nitrite or nitrate nitrogen by nitrifying bacteria, and then reducing the nitrite or nitrate nitrogen to nitrogen gas by denitrifying bacteria. Since the biological nitrification and denitrification method is a method of removing ammonia by a reaction using microorganisms, the decomposition activity of ammonia becomes unstable against various fluctuating factors. Furthermore, this method requires a large facility area and post-treatment after the ammonia treatment. Therefore, the biological nitrification-denitrification method has a low reliability of ammonia treatment and is not economical.

In the ammonia stripping method, an alkaline agent (e.g., sodium hydroxide, etc.) for pH adjustment is added to the wastewater to make the wastewater alkaline, and then the wastewater is contacted with a large amount of air to dissipate the ammonia in the wastewater into the atmosphere. is. In this method, as described above, the cost of the alkali agent for pH adjustment is high, and the ammonia diffused into the atmosphere is adsorbed and concentrated again. Therefore, the ammonia stripping method is not economical.

The chlorine oxidation method is a method of oxidizing ammonium ions in wastewater to nitrogen gas via chloramine by adding chlorine to the wastewater. In this method, the amount of chlorine added is about ten times that of ammonia. For this reason, the chlorine oxidation method is not suitable for treating wastewater with a high concentration of ammonia. Furthermore, the chlorine oxidation method carries out post-treatment of residual chlorine contained in the treated waste water. Therefore, the chlorine oxidation method is not economical.

In the catalytic cracking method, air is supplied to wastewater containing ammonia, and the ammonia in the wastewater is oxidized and reduced to nitrogen gas by contacting it with a high-performance catalyst under hot and pressurized conditions. It is a method of dissipating inside. This method, for example, reduces the catalytic activity when the waste water contains various metal ions such as iron, copper, zinc, and lead together with ammonia. This is because the metal ions become metal hydroxides and adhere to the ammonia contact catalyst or act as catalyst poisons as the pH in the ammonia contact catalyst reaction tower changes.

Thus, the typical ammonia removal methods exemplified above are expensive and tend to require high processing equipment costs.

Regarding the metal ion removal treatment by the coagulation-sedimentation method, it is conceivable to replace the coagulation-sedimentation method with a liquid chelate method or a chelate resin adsorption method. However, these methods have low removal efficiency of metal ions and are costly.

On the other hand, in the present embodiment, prior to treating the metal ions in the wastewater by the coagulation sedimentation method, the wastewater is brought into contact with an ammonia adsorbent to adsorb ammonia, and the ammonia in the wastewater is selectively removed. do. Ammonia adsorption is performed simply and economically. For example, an ammonia adsorption tower filled with an ammonia adsorbent is installed to adsorb ammonia and selectively remove ammonia. Then, in the present embodiment, after the ammonia is removed, the metal ions are separated by the subsequent coagulation-sedimentation method. Therefore, the method for treating wastewater containing metal ions and ammonia according to the present embodiment is simple and inexpensive, and the inhibition of aggregation and settling of metal ions due to ammine complexation of metal ions is suppressed. Therefore, metal ions can be treated more reliably.

<Drainage>
Wastewater to be treated in this embodiment is wastewater containing metal ions and ammonia. Waste water containing metal ions and ammonia is not particularly limited. Wastewater containing metal ions and ammonia includes, for example, wastewater generated from various factories such as fertilizer factories, dye factories, plating factories, and semiconductor factories, and wastewater generated from power plants. Waste water containing metal ions and ammonia may contain other components in addition to containing metal ions and ammonia.

Metal ions in waste water containing metal ions and ammonia include, for example, at least one metal ion selected from the group consisting of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, and lead. mentioned. Among these, the metal ions preferably include at least zinc metal ions. For example, as metal ions, zinc ions may be contained alone, or one or more metal ions other than zinc ions and zinc ions may be contained. The wastewater treatment method and the wastewater treatment apparatus according to the present embodiment can be suitably applied to wastewater containing at least zinc ions as metal ions in the wastewater containing metal ions and ammonia. For example, the wastewater treatment according to the present embodiment can also be applied to wastewater treatment when the wastewater to be treated is wastewater containing at least metal ions containing zinc ions and ammonia, such as wastewater generated from a galvanizing factory. A method and wastewater treatment apparatus are preferred.

Here, in the present specification, ammonia in waste water containing metal ions and ammonia refers to dissociated ammonium ions and undissociated ammonia in water.

<Ammonia adsorption step>
The ammonia adsorption step is a step of contacting waste water containing metal ions and ammonia with an ammonia adsorbent to cause the ammonia adsorbent to adsorb ammonia. When metal ions such as copper ions and zinc ions are contained as metal ions that form an ammine complex with ammonia in the waste water, these metal ions are completely eliminated even if the waste water is adjusted to be alkaline. , copper hydroxide and zinc hydroxide are difficult to deposit and remain in water as an ammine complex. Therefore, when waste water contains metal ions that form an ammine complex with ammonia as metal ions, the waste water is brought into contact with an ammonia adsorbent in advance to remove ammonia from the waste water. Since ammonia is removed from waste water containing metal ions and ammonia, the formation of ammine complexes is suppressed, and metal ions can be removed with high efficiency in the subsequent agglutination reaction step.

As long as ammonia can be removed by causing the ammonia adsorbent to adsorb ammonia, the method of adsorbing ammonia to the ammonia adsorbent is not particularly limited. As a means used for causing the ammonia adsorbent to adsorb ammonia, an ammonia adsorption tower is preferable from the viewpoint of easily and inexpensively treating waste water. The ammonia adsorbent and the ammonia adsorption tower will be detailed in the description of the ammonia adsorption tower below.

The concentration of ammonia contained in the wastewater after ammonia is removed by adsorbing ammonia in the ammonia adsorption step is preferably 0.6 mg/liter or less, more preferably 0.5 mg/liter or less. It is preferably 0.4 mg/liter or less, and more preferably 0.4 mg/liter or less. The lower limit of the concentration of ammonia contained in the wastewater after ammonia is removed by adsorption in the ammonia adsorption step is not particularly limited as long as it is below the detection limit. The lower limit of ammonia concentration may be, for example, 0 mg/liter or more, or may be more than 0 mg/liter. If the concentration of ammonia is 0.6 mg/liter or less, ammonia is considered to be removed in the subsequent coagulation-sedimentation treatment to an extent that does not impair the aggregation and sedimentation properties of metal ions in the coagulation-sedimentation treatment. can be done.

In the present embodiment, the method for measuring ammonia in wastewater contained in wastewater in each step of wastewater treatment is, for example, an indophenol blue absorptiometry method, a neutralization titration method, and an ion electrode method in accordance with JIS K 0102:2016. , ion chromatography, and flow analysis using indophenol blue coloration, and any of these methods may be used for measurement. Among these, the indophenol blue spectrophotometry method and the ion chromatography method are suitable for measuring ammonia in wastewater, and the indophenol blue spectrophotometry method is preferred because it is a simple measurement method. It is more suitable.

<Agglutination reaction step>
The ammonia adsorption step is a step of subjecting the waste water after adsorption of ammonia to aggregation reaction of metal ions by a coagulation sedimentation method. The coagulation-sedimentation method is not particularly limited as long as metal ions in the waste water can be removed. As the coagulation-sedimentation method, it is preferable to adopt the hydroxide method from the viewpoint of availability of chemicals and cost. The hydroxide method is a method in which a pH adjuster is added to react hydroxide ions with the metal ions of the target metal to deposit a metal hydroxide with low solubility.

In the hydroxide method, the alkaline agent as the pH adjuster is not particularly limited as long as it can precipitate metal ions as metal hydroxides. The alkaline agent is, for example, selected from the group consisting of sodium hydroxide (NaOH), which is so-called caustic soda, calcium hydroxide (Ca(OH) ₂ ), which is so-called slaked lime, and magnesium hydroxide (Mg(OH) ₂ ). At least one kind is mentioned. The alkaline agent is preferably at least one selected from the group consisting of sodium hydroxide and calcium hydroxide from the viewpoint of economy.

The pH range when the pH adjuster is added to the wastewater after adsorbing ammonia is not particularly limited, and the metal ions contained in the wastewater are precipitated as metal hydroxides and are not re-dissolved. good. In the flocculation reaction step, when the wastewater contains, for example, at least zinc ions as metal ions, the pH range to be adjusted when the zinc ions and hydroxide ions are flocculated is 9 or more and 11 or less. is preferred. If the pH range is 9 or more and 11 or less, zinc ions can be treated more reliably. In this embodiment, the alkaline agent is added after the ammonia is removed. Therefore, according to the present embodiment, the pH range in which metal ions can be removed is widened, making it easier to manage pH adjustment in coagulation sedimentation. Moreover, it is possible to reduce the residence time for the agglutination reaction treatment.

<Solid-liquid separation step>
The solid-liquid separation step is a step of performing a solid-liquid separation treatment on waste water (aggregation reaction water) after metal ions have undergone an aggregation reaction by a coagulation sedimentation method. In the solid-liquid separation step, for example, the coagulation reaction water is solid-liquid separated into supernatant water (coagulation treated water) and aggregates (sludge) by natural sedimentation or the like. Metal ions are removed as sludge by the solid-liquid separation process.

The concentration of metal ions contained in the aggregation reaction water is preferably 5 mg/liter or less, more preferably 4 mg/liter or less, even more preferably 3 mg/liter or less, and 2 mg/liter or less. is even more preferable. For example, when waste water containing ammonia and at least zinc ions is treated according to this embodiment, the concentration of zinc ions contained in the flocculation treated water can achieve 2 mg/liter or less. The lower limit of the metal ion concentration is not particularly limited as long as it is below the detection limit. The lower limit of the metal ion concentration may be, for example, 0 mg/liter or more, or may be more than 0 mg/liter.

In this embodiment, the method for measuring metal ions in wastewater contained in wastewater in each step of wastewater treatment is, for example, flame atomic absorption spectrometry, electric heating atomic absorption spectrometry, ICP (inductively Coupled Plasma) emission spectrometry, ICP mass spectrometry, and the like, and any of these methods may be used for measurement. Among these, the method for measuring metal ions in wastewater is preferably ICP emission spectrometry.

Hereinafter, the wastewater treatment method according to this embodiment will be described together with the wastewater treatment apparatus according to this embodiment with reference to the drawings. The invention is not limited to the content of the embodiments. In the drawings, some parts are enlarged or reduced for ease of explanation.

FIG. 2 schematically shows an example of a wastewater treatment apparatus according to this embodiment. As shown in FIG. 2, the waste water treatment apparatus 100 according to the present embodiment has an ammonia adsorption tower 20 installed upstream of the aggregation reaction tank 30A in the waste water treatment apparatus 1A shown in FIG. By applying the waste water treatment apparatus 100 shown in FIG. Therefore, in the wastewater treatment according to the present embodiment, metal ions can be subjected to coagulation sedimentation treatment while the influence of ammonia on the metal ions is suppressed.

The waste water treatment apparatus 100 shown in FIG. 2 includes a raw water tank 10 storing waste water containing metal ions and ammonia, and a waste water containing metal ions and ammonia flowing from the raw water tank 10, and bringing the waste water containing metal ions and ammonia into contact with an ammonia adsorbent 24 to produce ammonia. An ammonia adsorption tower 20 for adsorbing ammonia to an adsorbent 24, a coagulation reaction tank 30 for causing a coagulation reaction of metal ions in waste water after adsorbing ammonia flowing from the ammonia adsorption tower 20 by a coagulation sedimentation method, and a coagulation reaction tank. and a coagulation sedimentation tank 50 for solid-liquid separation of the waste water flowing in from 30 and subjected to the coagulation reaction. The wastewater treatment device 100 further includes a filter 70 that filters the wastewater flowing from the coagulating sedimentation tank 50 .

The wastewater treatment method using the wastewater treatment apparatus 100 according to the present embodiment treats wastewater containing metal ions and ammonia through the following steps.

First, waste water (water to be treated) containing metal ions and ammonia is sent to the raw water tank 10 as waste water discharged from various factories or power plants. In the raw water tank 10, raw water 12 as waste water containing metal ions and ammonia, which is water to be treated, is temporarily stored. The raw water 12 contains at least some of the metal ions forming an ammine complex with ammonia.

The raw water 12 stored in the raw water tank 10 is sent through the pipeline 13 by the pump 11 and flows into the ammonia adsorption tower 20 . In the ammonia adsorption tower 20 , ammonia in waste water is adsorbed by the ammonia adsorbent 24 . In the waste water treatment apparatus 100, the ammonia adsorption tower 20 contains, for example, zeolite as the ammonia adsorbent 24. As shown in FIG. Ammonia in the waste water containing metal ions and ammonia is adsorbed by the ammonia adsorbent 24 . Ammonia is adsorbed by the ammonia adsorption tower 20 and removed. Ammonia is coagulated and precipitated when metal ions are removed in the latter stage, and is removed to such an extent that it is not affected by ammonia. Ammonia adsorption-treated water 22, which is waste water after ammonia has been adsorbed, contains metal as ions of simple metals.

The ammonia adsorption-treated water 22 is sent through the pipe 23 by the pressure of the pump 11 and flows into the aggregation reaction tank 30 . In the agglutination reaction tank 30, the chemical solution 36 is supplied from the tank 35 containing the chemical solution 36 through the pipeline 37 by a pump (not shown). In the waste water treatment equipment 100, the hydroxide method is applied as the coagulation sedimentation method. In the wastewater treatment apparatus 100, the tank 35 contains, as the chemical solution 36, an alkaline agent such as slaked lime as a pH adjuster. The aggregation reaction tank 30 is provided with a stirrer (not shown), and is stirred by the stirrer. The waste water after stirring overflows as the coagulation reaction water 32 , is sent through the pipeline 33 , and flows into the coagulation sedimentation tank 50 .

In the coagulation-sedimentation tank 50, aggregates contained in the fed coagulation-reaction water 32 precipitate as sludge 54, and the coagulation-reaction water 32 undergoes solid-liquid separation into precipitated sludge 54 and coagulation-treated water 52 as supernatant water. be done. The sludge 54 is drawn out from the lower part of the coagulating sedimentation tank 50 by a pump (not shown). The flocculated water 52 is sent to the filter 70 through the pipeline 53 and filtered by the filter 70 . Then, the filtered water 72 is discharged to a river or the like as treated water.

(Raw water tank)
The raw water tank 10 is provided to temporarily store waste water containing metal ions and ammonia. The raw water tank 10 is not particularly limited as long as it has a structure capable of storing waste water containing metal ions and ammonia, and various shapes, materials, and the like can be used. The capacity of the raw water tank is not particularly limited, and may be determined according to the amount of wastewater to be treated. The raw water tank 10 may be provided with, for example, a circulation mechanism (not shown) for circulating the raw water 12 . Examples of the circulation mechanism include a stirrer. In the waste water treatment apparatus 100 shown in FIG. 2, the raw water tank 10 is provided, but the raw water tank 10 is not provided. can be configured to

(Ammonia adsorption tower)
The ammonia adsorption tower 20 is used to bring waste water containing metal ions and ammonia into contact with an ammonia adsorbent. In the waste water treatment apparatus 100, in the ammonia adsorption tower 20, the ammonia is selectively removed by bringing the waste water into contact with the ammonia adsorbent 24 and causing the ammonia adsorbent 24 to adsorb ammonia. By passing the raw water 12 through the ammonia adsorption tower 20, ammonia is removed to an extent that does not hinder the aggregation and settling properties of metal ions when the aggregates are insolubilized in the subsequent coagulation sedimentation treatment.

The ammonia adsorption tower 20 is not particularly limited as long as it can adsorb and remove ammonia, and various structures can be adopted. It is preferable that the ammonia adsorption tower 20 is detachable in the path of the front stage of the aggregation reaction tank 30 in the waste water treatment apparatus 100 from the viewpoint of realizing simplicity and low cost. Specifically, the ammonia adsorption tower 20 includes a pipeline 13, which is a route through which waste water containing metal ions and ammonia is sent, and a waste water after adsorption of ammonia (that is, ammonia adsorption treated water 22) is sent. It is preferable that it is attachable to and detachable from the pipeline 23, which is the route through which If the ammonia adsorption tower 20 is configured to be detachable in the path of the front stage of the aggregation reaction tank 30 in the waste water treatment apparatus 100, after the ammonia adsorption capacity of the ammonia adsorption material 24 is lowered, the ammonia adsorption tower 20 itself can be exchanged. By replacing the ammonia adsorption tower 20 with an ammonia adsorption tower 20 filled with an ammonia adsorption material 24 capable of adsorbing ammonia, it becomes possible to adsorb a certain amount of ammonia again.

The concentration of ammonia contained in the waste water after the ammonia is removed by adsorption in the ammonia adsorption tower 20 is preferably within the range described in the ammonia removal step.

FIG. 3 schematically represents an example of a preferred embodiment of an ammonia adsorption tower applied as the ammonia adsorption tower 20 shown in FIG. As shown in FIG. 3, the ammonia adsorption tower 200 includes an ammonia adsorbent 204, an adsorbent-filled container 202 that houses the ammonia adsorbent 204, and a path through which waste water containing metal ions and ammonia is fed. A supply port side connection member 214 and a discharge port side connection member 218 provided on the side of a path through which waste water after adsorbing ammonia is fed are provided. Inside the adsorbent filling container 202, a filter 206 is provided at the lower outlet side of the ammonia adsorbent 204 so that the ammonia adsorbent 204 does not leak. The supply port side connecting member 214 is attached to the adsorbent-filled container 202 via the supply port 212 , and the discharge port side connection member 218 is attached to the adsorbent-filled container 202 via the discharge port 216 . there is

In the ammonia adsorption tower 200, the adsorbent-filled container 202 is provided with a sufficient capacity for passing the wastewater containing metal ions and ammonia. The adsorbent-filled container 202 is made of one or more of metal, resin, and fiber-reinforced resin. The shape of the cross section obtained by cutting the adsorbent filled container 202 in the direction perpendicular to the direction of gravity is circular. The cross-sectional shape of the adsorbent-filled container 202 taken perpendicularly to the direction of gravity is not limited to a circle, and may be a triangle, a square, or a polygon with pentagons or more. The inside of the adsorbent-filled container 202 is filled with a sufficient amount of ammonia adsorbent 204 to adsorb ammonia and selectively remove ammonia. In the ammonia adsorption tower 200, the shape of the ammonia adsorbent 204 filled in the adsorbent packed container 202 is particulate. Further, the ammonia adsorbent 204 filled in the adsorbent filling container 202 is filled in a cylindrical shape.

The filling amount of the ammonia adsorbent 204 housed inside the adsorbent filling container 202 and the filling rate of the ammonia adsorbent 204 are such that the passage resistance of waste water is not excessively increased, and ammonia can be efficiently adsorbed and removed. You should consider and decide.

The ammonia adsorbent 204 housed inside the adsorbent filling container 202 is preferably configured to be replaceable. The ammonia adsorbent 204 adsorbs a certain amount of ammonia, and can be replaced after its ability to adsorb ammonia decreases. When the ammonia adsorbent 204 has a reduced ability to adsorb ammonia, the ammonia adsorbent 204 can be subjected to a regeneration process to release ammonia from the ammonia adsorbent 204 by using a regeneration agent. The regenerated ammonia adsorbent 204 can be reused by filling the inside of the adsorbent filling container 202 . Alternatively, the ammonia adsorbent 204 whose ability to adsorb ammonia has decreased can be disposed of without being regenerated.

In the ammonia adsorption tower 200, a supply port side connecting member 214 and a pipeline on a path side to which waste water (water to be treated) containing metal ions and ammonia is fed are connected, and an outlet side connecting member 218 and ammonia are connected. It is used by being connected to a pipeline on the side of a path through which waste water after adsorption (that is, ammonia adsorption-treated water) is fed. The water to be treated flows in from the supply port side connecting member 214 and the supply port 212, and is selectively removed by the ammonia adsorbent 204 filled inside the adsorbent filled container 202, where ammonia is adsorbed. After that, the ammonia adsorption-treated water is discharged through the discharge port 216 and the discharge port side connection member 218 .

As the supply port side connection member 214 and the discharge port side connection member 218, for example, connection members such as flanges and couplers are used. From the viewpoint of facilitating replacement of the ammonia adsorption tower, it is preferable to apply a coupler to both the supply port side connecting member 214 and the discharge port side connecting member 218 . When both the supply port side connection member 214 and the discharge port side connection member 218 are couplers, the connection member provided in the pipeline for conveying the water to be treated and the connection member provided for the pipeline for conveying the ammonia adsorption-treated water. A coupler is also applied to If both the supply port side connection member 214 and the discharge port side connection member 218 are couplers, the coupler of the supply port side connection member 214 and the coupler of the pipeline to which the water to be treated is conveyed are connected, and the discharge port side connection member By simply connecting the coupler 218 and the coupler of the pipeline to which the ammonia-adsorbed water is fed, attachment and detachment to and from the wastewater treatment apparatus can be facilitated. For example, consider replacing an old ammonia adsorption tower with a reduced ammonia adsorption capacity with a new ammonia adsorption tower with sufficient ammonia adsorption capacity. At this time, each coupler provided in the old ammonia adsorption tower can be detached from the coupler provided in each pipeline, and each coupler provided in the new ammonia adsorption tower can be attached and detached simply by reconnecting the coupler provided in each pipeline to the coupler provided in each pipeline. This facilitates replacement of the ammonia adsorption tower.

Further, it is preferable that both the supply port side connection member 214 and the discharge port side connection member 218 are couplers, because the wastewater treatment apparatus can be operated with the loss of the operating rate kept to a minimum.

The ammonia adsorption tower 200 may be provided with a support (not shown) on which the ammonia adsorption tower 200 is installed. A support stand (not shown) may be configured to be movable in the ammonia adsorption tower 200 . The support base may be provided by directly attaching to the ammonia adsorption tower 200 . Alternatively, the support may be provided such that the ammonia adsorption tower 200 is mounted on the support and the support is removable from the ammonia adsorption tower 200 .

The ammonia adsorbent 204 with which the ammonia adsorption tower 200 is filled is not particularly limited as long as it is an adsorbent capable of adsorbing ammonia. Examples of the ammonia adsorbent 204 include at least one selected from the group consisting of activated carbon, alumina, silica, and zeolite. Among these, the ammonia adsorbent 204 preferably contains at least zeolite, more preferably zeolite, from the viewpoint of selective adsorption of ammonia and low cost. Zeolite has fine and nearly uniform pore diameters, so that it can selectively adsorb ammonia and can remove ammonia with high efficiency. Zeolite is abundant in reserves in Japan and is inexpensive.

Zeolites are hydrous aluminosilicates containing alkali or alkaline earth metals. The zeolite is not particularly limited, and may be a natural zeolite mined from nature, a synthetic zeolite produced by chemical synthesis, or an artificial zeolite produced from coal ash or the like. Natural zeolites are preferred because they are cheaper. Zeolites are classified into, for example, mordenite, clinoptilolite, analcyme, and ferrierite. Any zeolite can be used in this embodiment. Among these, the zeolite is preferably mordenite-type zeolite. Mordenite-type zeolite has a pore size suitable for adsorbing ammonia, and is excellent in selective adsorption of ammonia due to the pore size. In addition, mordenite-type zeolite is less susceptible to crystal collapse due to acid. Therefore, for example, it can be suitably used for acidic waste water containing ammonia (for example, zinc chloride bath, etc.).

From the viewpoint of efficiently adsorbing ammonia, the pore diameter of the zeolite is, for example, preferably 0.3 nm or more and 1 nm or less, and more preferably 0.3 nm or more and 0.8 nm or less.

The space velocity SV (Space Velocity: the amount of liquid passing per hour expressed as a multiple of the volume of the adsorbent) for passing wastewater containing metal ions and ammonia through the ammonia adsorption tower efficiently adsorbs ammonia, There are no particular limitations as long as ammonia can be removed. The space velocity SV may be, for example, in the range of 0.6 or more and 1.2 or less.

The number of ammonia adsorption towers is not limited to one, and for example, a plurality of towers may be provided. Further, a plurality of ammonia adsorption towers may be arranged in series or may be arranged in parallel. Furthermore, from the viewpoint of suppressing a decrease in the operation rate of the treatment equipment, a backup ammonia adsorption tower that can switch the ammonia adsorption line so that the ammonia in the wastewater can be adsorbed even when the ammonia adsorption tower is replaced. may be provided.

(aggregation reactor)
The aggregation reaction tank 30 is provided for reacting the metal ions in the wastewater from which the ammonia has been removed with the chemical solution. As described above, the agglutination reaction tank 30 is provided with a chemical solution supply path so that an alkali agent (for example, hydrated lime) as a pH adjuster can be supplied as the chemical solution 36 . The structure of the coagulation reaction tank 30 is not particularly limited as long as the coagulation reaction tank 30 can supply a chemical solution to the waste water from which the ammonia has been removed from the waste water containing metal ions and ammonia to cause the coagulation reaction. , various shapes, materials, etc. can be used. The agglutination reaction tank 30 preferably has a circulation mechanism such as a stirrer (not shown) from the viewpoint of bringing the metal ions into contact with the chemical solution and facilitating the reaction between the metal ions and the chemical solution.

The aggregation reaction tank 30 may be configured so as to supply at least one of an acid as a pH adjuster and a flocculating agent along with the supply of the alkaline agent, if necessary. In this case, the chemical solution supply route may be provided with a supply route different from the supply route of the alkaline agent. For example, as the second supply route, a tank containing an acid (e.g., hydrochloric acid, sulfuric acid, etc.) as a pH adjuster, and a supply route including a pump and a pipeline for supplying the acid may be provided. As the third supply route, a tank containing a flocculant (for example, a polymer flocculant, an inorganic flocculant, etc.) and a supply route having a pump and a pipeline for supplying the flocculant may be provided. In this case, the second supply route and the third supply route each pump acid or a flocculating agent as a pH adjuster and supply it to the agglutination reaction tank 30 through a pipeline.

The number of aggregation reaction tanks 30 is not limited to one, and a plurality of tanks may be provided. For example, when using a flocculating agent, in addition to providing a first flocculation reaction tank for adding an alkaline agent as a pH adjuster, a second flocculation reaction tank for adding an acid as a pH adjuster, and a third agglutination reactor for adding a flocculant. Further, for example, when using a flocculant, an area for adding a pH adjuster and an area for adding a flocculant are provided inside one agglutination reaction tank 30, and partitioned by a partition plate. may be configured. The structure, number, etc. of the agglutination reaction tanks may be determined in consideration of treatment efficiency, installation area, installation cost, and the like.

(coagulation sedimentation tank)
The coagulation-sedimentation tank 50 is provided to separate the supernatant water and sludge by allowing the metal ions in the wastewater from which ammonia has been removed to react with the chemical solution, and then allowing them to stand. In the coagulation-sedimentation tank 50, the coagulation produced by the reaction between the metal ions and the chemical solution 36 (the alkaline agent as the pH adjuster in the waste water treatment apparatus 100 shown in FIG. 2) settles as sludge 54, and the sludge 54 , and a flocculation treated water 52 as supernatant water. The coagulation-sedimentation tank 50 is not particularly limited as long as it has a structure capable of solid-liquid separation into the sludge 54 and the coagulation-treated water 52 . Various shapes, materials, and the like can be used for the structure of the agglutination reaction tank 30 . The coagulating sedimentation tank 50 preferably has a structure in which, for example, the sludge 54 is withdrawn from the lower part of the coagulating sedimentation tank 50 and is connected to a device for mechanically dehydrating the withdrawn sludge 54 .

The number of coagulation sedimentation tanks is not limited to one, and a plurality of tanks may be provided. The structure, number, etc. of the coagulating sedimentation tanks may be determined in consideration of treatment efficiency, installation area, installation cost, and the like.

(filter)
The filter 70 is provided to remove flocs, suspended matter, and the like contained in the flocculated water 52 . The filter 70 is not particularly limited as long as it can remove flocs and suspended matter contained in the coagulated water 52 . Various structures are adopted for the filter 70 . In addition, although the filter 70 is provided in the waste water treatment apparatus 100 shown in FIG. Moreover, although the filter 70 was provided in FIG. 2, the filter 70 may not be provided.

(Action and effect of the present embodiment)
According to this embodiment, the following effects can be obtained.
(1) According to the wastewater treatment method of the present embodiment, wastewater containing metal ions and ammonia can be treated easily and inexpensively, and metal ions can be treated more reliably.
(2) According to the wastewater treatment method according to the present embodiment, after the ammonia is removed, the pH is adjusted and the precipitated metal hydroxide is separated into solid and liquid, thereby forming metal ions and ammonia. Metal ions can be removed from the waste water without the inhibition of flocculation and sedimentation by ammine complexes.
(3) According to the wastewater treatment method according to the present embodiment, since metal ions are removed by the coagulation sedimentation method after ammonia is removed, the removable pH range when removing metal ions is widened, It is possible to make it easier to control the pH during coagulation sedimentation and reduce the residence time (standing time) in coagulation sedimentation.

[Modification of Embodiment]
The invention is not limited to the embodiments described above. The present invention can include modifications, improvements, and the like within the scope of achieving the object of the present invention.

Although not shown in FIG. 2, before the treated water treated by this embodiment is discharged to a river or the like, for example, the pH of the treated water is 5 or more and 8 or less (preferably pH is 6 or more and 7 or less). A pH adjusting means may be provided so that the pH falls within the range. Furthermore, the treated water treated by the present embodiment may be configured not only to be discharged into a river or the like, but also to be reused as industrial water at least part of the treated water.

In FIG. 2, the form in which the aggregation reaction water is fed by overflowing is described. The coagulation reaction water is not limited to this, and instead of feeding the coagulation reaction water by causing it to overflow, for example, the coagulation reaction water may be fed by a pump so that the coagulation reaction water flows into the coagulation sedimentation tank.

In FIG. 2, the coagulation reaction step and the solid-liquid separation step are performed in the waste water treatment apparatus separately provided with the coagulation reaction tank and the coagulation sedimentation tank. Not limited to this, the agglutination reaction step and the solid-liquid separation step are performed by integrating the flocculation reaction tank and the flocculation sedimentation tank so as to combine the functions of flocculation reaction and flocculation sedimentation and solid-liquid separation. You may perform by the wastewater treatment apparatus provided. The aggregation reaction step and the solid-liquid separation step may be performed, for example, in batch mode.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. However, each of these examples does not limit the present invention.

[Example 1]
Galvanized waste water containing 530 mg/liter of ammonium ions, 38 mg/liter of zinc, and 1000 mg/liter of chlorine was prepared as waste water to be treated. Mordenite-type zeolite (Nitto Funka Kogyo Co., Ltd., Nitto Zeolite No. 2) was prepared as an ammonia adsorbent. As a pretreatment, the zeolite was washed with water. After that, 1300 mL of the washed zeolite was filled in a packed container of the ammonia adsorption tower to a height of 660 mm and a diameter of 50 mm to prepare the ammonia adsorption tower. The zinc plating waste water was passed through an ammonia adsorption tower at a SV (Space Velocity) of 1.2 (1600 mL/h), and the ammonia was adsorbed by the ammonia adsorbent to remove ammonia from the zinc plating waste water. Next, slaked lime was added to the ammonia adsorption-treated water from which ammonia was removed, and coagulation sedimentation was performed by the hydroxide method.

[Comparative Example 1]
Coagulation sedimentation by the hydroxide method was performed in the same manner as in Example 1 except that the ammonia adsorption tower prepared in Example 1 was not used and the zinc plating wastewater prepared in Example 1 was not passed through the ammonia adsorption tower. gone.

[evaluation]
<Concentration of components in ammonia adsorption-treated water>
Concerning Example 1, the concentrations of zinc ions, ammonia, and chlorine contained in the ammonia adsorption tower treated water after the zinc plating wastewater was passed through the ammonia adsorption tower were measured. The concentration of zinc ions was measured by ICP emission spectroscopy, and the concentrations of ammonia and chlorine components were measured by ion chromatography. Table 1 shows the measurement results.

<Concentration of components in coagulation-sedimentation-treated water>
For both Example 1 and Comparative Example 1, the zinc plating wastewater prepared above was subjected to coagulation sedimentation by the hydroxide method with pH adjustment using slaked lime, and then the zinc ion concentration of the supernatant water (coagulation sedimentation treated water) compared. The concentration of zinc ions was measured by ICP emission spectroscopy. The zinc ion concentration (mg / liter) contained in the coagulation-sedimentation treated water at each pH when adjusting the pH with slaked lime is 15 minutes of high-speed stirring and 15 minutes of low-speed stirring to coagulate the flocs, and 15 minutes or more. It was measured after standing still. Table 2 shows the measurement results. The high-speed rotation is the number of rotations at which a vortex is generated on the surface of the liquid, and the low-speed rotation is the number of rotations at which the surface of the liquid is slightly vortexed.

FIG. 4 shows the results of Example 1 (labeled as E1 in FIG. 4) and Comparative Example 1 (labeled as C1 in FIG. 4). Specifically, FIG. 4 is a graph showing the concentration of zinc (Zn) ions in supernatant water at each pH after coagulation sedimentation by the hydroxide method with pH adjustment using slaked lime. In Example 1, in the pH range from pH 9 to 12, the concentration of zinc contained in the coagulation-sedimentation-treated water could be reduced to 2 mg/liter or less. Therefore, it can be seen that zinc ions can be treated more reliably by performing coagulation precipitation by the hydroxide method after removing ammonia.

On the other hand, in Comparative Example 1, it could not be confirmed that the concentration of zinc contained in the coagulation-sedimentation-treated water was reduced to 2 mg/liter or less in the pH range from pH 8 to 12.

The results of Example 1 and Comparative Example 1 show that by removing ammonia in waste water in advance, metal ions and metal ions contained in ammonia-containing waste water can be treated more reliably. indicates that there is

[Example 2]
Coagulation sedimentation by the hydroxide method was performed in the same manner as in Example 1, except that galvanized wastewater containing 520 mg/liter of ammonium ions, 170 mg/liter of zinc, and 1200 mg/liter of chlorine was prepared as the wastewater to be treated. did

[Comparative Example 2]
Coagulation sedimentation by the hydroxide method was performed in the same manner as in Example 2 except that the ammonia adsorption tower prepared in Example 2 was not used and the zinc plating wastewater prepared in Example 2 was not passed through the ammonia adsorption tower. gone.

[evaluation]
<Concentration of components in ammonia adsorption-treated water>
Regarding Example 2, in the same manner as in Example 1, the concentrations of zinc ions and ammonia components contained in the ammonia adsorption tower treated water after passing through the ammonia adsorption tower were measured. Table 3 shows the measurement results. In Example 2, the concentration of the chlorine component was not measured.

<Floc settling property of coagulation-sedimentation treated water>
For both Example 2 and Comparative Example 2, the zinc plating waste water prepared above was adjusted to pH 11 with slaked lime, and floc sedimentation properties during coagulation sedimentation by the hydroxide method were compared. The sedimentation property of flocs was determined by the following procedure. First, the pH of zinc plating waste water was adjusted to 11. After that, the pH-adjusted waste water was subjected to high-speed stirring for 15 minutes and low-speed stirring for 15 minutes. The degree of high-speed stirring and low-speed stirring is similar to that described in Example 1. Subsequently, 150 mL of the liquid after low-speed stirring was gently poured into a 200 mL graduated cylinder and allowed to stand, and the transition of sedimentation of flocs was measured. The transition of floc sedimentation was confirmed by measuring the distance (mm) from the liquid surface to the sedimentation surface on which the flocs were sedimented every hour (minute). The distance from the liquid surface to the sedimentation surface where the flocs have settled is the distance (height) measured at the part where the turbidity of the supernatant water becomes the same turbidity as when the liquid after low-speed stirring is left for one day. . A larger distance value indicates that flocs are more likely to settle. Table 4 shows the measurement results.

FIG. 5 shows the results of Example 2 (labeled as E2 in FIG. 5) and Comparative Example 2 (labeled as C2 in FIG. 5). Specifically, in FIG. 5, when the pH was adjusted to 11 with slaked lime and the turbidity of the supernatant water became equivalent to that when left for one day by the hydroxide method, flocs settled from the liquid surface. It is a graph which shows transition of the height to a subsidence surface. In Example 2, it settled down to 132 mm from the liquid surface after 15 minutes, and almost all of the flocs were able to settle on the bottom surface. Therefore, it can be seen that zinc can be treated more reliably by performing coagulation sedimentation by the hydroxide method after removing ammonia.

On the other hand, in Comparative Example 2, even after 15 minutes, the flocs settled only up to 11 mm from the liquid surface, and it was not confirmed that the standing time for coagulation sedimentation was reduced.

The results of Example 2 and Comparative Example 2 show that by removing ammonia in waste water in advance, metal ions and metal ions contained in waste water containing ammonia can be treated more reliably. indicates that there is

[Example 3]
Galvanized wastewater containing 39 mg/liter of ammonium ions, 26 mg/liter of iron, and 160 mg/liter of zinc was prepared as the wastewater to be treated. Mordenite-type zeolite (Nitto Funka Kogyo Co., Ltd., Nitto Zeolite No. 2) was prepared as an ammonia adsorbent. After washing the zeolite with water, 625 L of the washed zeolite was filled in a cylindrical shape with a height of 1450 mm and a diameter of 750 mm to prepare an ammonia adsorption tower. The zinc plating waste water was passed through the ammonia adsorption tower at 700 L/h, and the ammonia was adsorbed by the ammonia adsorbent to remove the ammonia from the zinc plating waste water. Next, slaked lime was added to the ammonia adsorption-treated water from which ammonia was removed to adjust the pH to 10, and coagulation sedimentation treatment was performed by the hydroxide method. The ammonia concentration of the ammonia adsorption-treated water and the metal ion concentration of the coagulation-sedimentation-treated water were measured. Table 5 shows the measurement results.

表５に示すように、実施例３の結果は、鉄の濃度が０．１ｍｇ／リットル未満（検出下限値以下）、及び亜鉛０．１ｍｇ／リットル未満（検出下限値以下）に処理することができた。

As shown in Table 5, the results of Example 3 show that iron concentrations of less than 0.1 mg/liter (below the detection limit) and zinc less than 0.1 mg/liter (below the detection limit) can be treated. did it.

From the results of each comparative example, it can be seen that there are metal components that cannot be removed only by the treatment of adjusting the alkalinity of waste water containing metal ions and ammonia and then filtering it. On the other hand, from the results of each example, by removing ammonia from wastewater containing metal ions and ammonia using an ammonia adsorption tower, it is possible to perform coagulation sedimentation treatment by the hydroxide method in a wider pH range. It turned out to be

According to the results of the above examples, after the wastewater is passed through the ammonia adsorption tower to remove ammonia from the wastewater containing ammonia and metal ions, the pH is adjusted to separate the precipitated metal hydroxide into solid and liquid. As a result, it is possible to more reliably treat wastewater containing metal ions in a wide pH range, easily and inexpensively, without being affected by the ammine complex formed by the metal and ammonia. .

10, 10A... raw water tank, 11, 11A,... pump, 12, 12A... raw water, 13, 13A, 23, 33, 33A, 37, 37A, 53, 53A... pipeline, 20, 200... ammonia adsorption tower, 22 ... ammonia adsorption treated water, 24, 204 ... ammonia adsorbent, 30, 30A ... aggregation reaction tank, 32, 32A ... aggregation reaction water, 35, 35A ... tank, 36, 36A ... chemical liquid, 50, 50A ... coagulation sedimentation tank, 52, 52A... Aggregated treated water, 54, 54A... Sludge, 70, 70A... Filter, 72, 72A... Filtrated treated water, 1A, 100... Waste water treatment equipment, 202... Adsorbent filled container, 206... Filter, 212... Supply port 214 Supply port side connection member 216 Discharge port 218 Discharge port side connection member.

Claims (9)

A method for treating wastewater containing metal ions and ammonia,
The processing method is
A step of contacting the waste water containing the metal ions and the ammonia with an ammonia adsorbent to cause the ammonia adsorbent to adsorb the ammonia;
a step of causing the metal ions to coagulate in the wastewater after the ammonia has been adsorbed by a coagulation sedimentation method;
A step of solid-liquid separation treatment of the waste water after the aggregation reaction;
comprising
A method for treating wastewater containing metal ions and ammonia. In the method for treating wastewater containing metal ions and ammonia according to claim 1,
The ammonia adsorbent is zeolite,
A method for treating wastewater containing metal ions and ammonia. In the method for treating wastewater containing metal ions and ammonia according to claim 1 or 2,
The coagulation sedimentation method is a hydroxide method,
A method for treating wastewater containing metal ions and ammonia. In the method for treating wastewater containing metal ions and ammonia according to any one of claims 1 to 3,
The aggregating step includes adding a pH adjuster to the waste water after adsorbing the ammonia to adjust the pH to a range of 9 or more and 12 or less, and causing the metal ions to undergo the aggregation reaction by the coagulation sedimentation method. is a process,
A method for treating wastewater containing metal ions and ammonia. A wastewater treatment device containing metal ions and ammonia,
The processing device is
an ammonia adsorption tower for bringing the wastewater containing the metal ions and the ammonia into contact with an ammonia adsorbent to adsorb the ammonia on the ammonia adsorbent;
a coagulation reaction tank in which the metal ions are subjected to a coagulation reaction by a coagulation-sedimentation method in the waste water after the ammonia has been adsorbed flowing in from the ammonia adsorption tower;
a coagulation-sedimentation tank for solid-liquid separation of the wastewater after the coagulation reaction flowing in from the coagulation reaction tank;
comprising
Equipment for treating wastewater containing metal ions and ammonia. Ammonia adsorption tower used in the method for treating waste water containing metal ions and ammonia according to any one of claims 1 to 4, or the equipment for treating waste water containing metal ions and ammonia according to claim 5. and
The ammonia adsorption tower is
Used for contacting waste water containing the metal ions and the ammonia with the ammonia adsorbent,
Ammonia adsorption tower. In the ammonia adsorption tower according to claim 6,
The ammonia adsorption tower is attachable to and detachable from a route through which the waste water containing the metal ions and the ammonia is fed and a route through which the waste water after adsorbing the ammonia is fed.
Ammonia adsorption tower. In the ammonia adsorption tower according to claim 6 or claim 7,
The ammonia adsorption tower is
the ammonia adsorbent;
an adsorbent-filled container containing the ammonia adsorbent;
a supply port side connection member provided on the side of a path through which the waste water containing the metal ions and the ammonia is fed;
an outlet-side connecting member provided on the side thereof with a path through which the waste water after adsorbing the ammonia is conveyed;
comprising
Ammonia adsorption tower. In the ammonia adsorption tower according to claim 8,
The ammonia adsorbent housed in the adsorbent-filled container is replaceable,
Ammonia adsorption tower.

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