JP3305179B2 - Wastewater treatment method and wastewater treatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method and a wastewater treatment apparatus capable of effectively removing selenium (particularly hexavalent Se) in wastewater.

[0002]

2. Description of the Related Art Generally, as a flue gas desulfurization apparatus provided in a thermal power generation facility or the like, a wet flue gas system in which flue gas is brought into contact with an adsorbent slurry (eg, limestone slurry) to absorb and remove sulfur oxides in the flue gas. However, since the wastewater from this flue gas desulfurization system contains harmful substances present in the flue gas, it must be discharged or reused after detoxification. There is. In particular, in a flue gas treatment system for a coal-fired boiler, a maximum of 10 mg / kg of coal
The harmful effect of selenium (Se) contained in a small amount has recently become a problem, and it has been desired to remove selenium (Se) from wastewater. Se has toxicity similar to arsenic compounds,
Since there are cases of obstacles and emission regulations overseas,
Regulations were newly added in February 994, and environmental standards (0.01 mg / l), wastewater standards (0.1 mg / l),
The dissolution standard (0.3 mg / l) for landfill disposal was established. Se is tetravalent Se in the wastewater (main form:
There are SeO ₂ ^2- selenite and hexavalent Se (main form: SeO ₄ ^2- selenate). Particularly, hexavalent Se has high solubility (solubility 95% at 20 ° C) and is easily eluted.

[0003] By the way, for conventional tetravalent Se, Fe
It is insolubilized by Cl ₃ or Fe ₂ (SO ₄ ) ₃ , a chelating agent (for example, trade name: Miyoshi resin EPORAS MX-7), or a polymer heavy metal collecting agent (for example, trade name: Miyoshi resin Epofloc L-1). Thus, a method of removing by solid-liquid separation is known as a practical one. However, there has been no practical and effective method for removing hexavalent Se.

[0004]

For this reason, conventionally, when hexavalent Se is contained in the wastewater, the desulfurization wastewater or the like is diluted with, for example, a large amount of water in order to comply with the elution standard and the like. There was a problem that expensive processing was required.

Accordingly, an object of the present invention is to provide a wastewater treatment method and a wastewater treatment apparatus that can effectively absorb and remove at least hexavalent Se in wastewater at low cost.

[0006]

In order to achieve the above object, a method for treating wastewater according to claim 1 of the present invention comprises an eggshell membrane,
By contacting the wastewater with an adsorbent composed of at least one biological material selected from feathers and wool,
It is characterized in that at least hexavalent Se in waste water is removed.

According to a second aspect of the present invention, there is provided a wastewater treatment method.
At the time of the removal treatment, the pH of the treatment solution containing the wastewater is adjusted to 2 to 8
Preferably, it is adjusted to 4 to 6.

[0008] A wastewater treatment method according to a third aspect of the present invention is characterized in that the biological material is used as the adsorbent in the first or second aspect in a solid state.

According to a fourth aspect of the present invention, there is provided a wastewater treatment method.
In the present invention, the adsorbent according to claim 1 or 2 is characterized by using a powder or liquid of the biological material.

[0010] The wastewater treatment apparatus according to claim 5 of the present invention comprises:
A wastewater treatment apparatus for removing at least hexavalent Se from wastewater, wherein an adsorbent composed of at least one biological material selected from eggshell membranes, feathers and wool is loaded in a fixed state and treated. A fixed-bed type contact treatment tower configured to allow wastewater to pass therethrough.

[0011] The wastewater treatment apparatus according to claim 6 of the present invention comprises:
A wastewater treatment device for removing at least hexavalent Se from wastewater, comprising an adsorbent comprising at least one biological material selected from eggshell membranes, feathers and wool, and wastewater to be treated. An adsorption treatment tank to be mixed
And a solid-liquid separation means for removing solids from wastewater containing the adsorbent derived from the adsorption treatment tank.

[0012]

Embodiments of the present invention will be described below. First, the adsorbent used in the wastewater treatment method or wastewater treatment device of the present invention will be described. As the biological material constituting the adsorbent, any one of eggshell membrane, feathers and wool may be used alone, or a plurality of them may be combined. In addition, these biological materials can be used as they are in a solid state (including a film form), as described later, to reduce the number of processing steps. However, they can be stored and transported by grinding them into powder or liquefying them. Or, handling such as supply to the apparatus becomes easy.

[0013] For example, chicken eggs are used in large quantities in the food industry, and eggshells (with shell membranes) produced at that time are currently dumped in large quantities. For this reason, eggshell membranes
For example, it can be obtained inexpensively and in large amounts from eggshells of chickens used at mayonnaise factories and the like. And such a chicken eggshell,
First, it is immersed in a 5 wt% hydrochloric acid solution for about 10 hours to dissolve the eggshell mainly composed of calcium carbonate. And
If the remaining eggshell membrane is washed with distilled water to remove dust and the like, and dried and then washed with a 0.1N sodium hydroxide solution to remove egg white and the like, it has a high adsorption capacity of Se or Hg as described later. A clean eggshell membrane is obtained. The eggshell membrane can be used as an adsorbent without being separated from the eggshell. In this case, the above-mentioned pretreatment with the hydrochloric acid solution becomes unnecessary, and the eggshells (with shell membrane) used at the mayonnaise factory or the like are washed with distilled water while keeping the shell, dried, and then dried with sodium hydroxide solution. What is necessary is just to wash.

Next, the feather or wool is, for example, 0.1 N
Washing with 0.5N sodium hydroxide solution to remove oils and the like, and then washing with distilled water completes the pretreatment, and clean feathers or wool having a high adsorption capacity of Se or Hg as described later. Is obtained. In addition, feathers of various birds (for example, chicken feathers) can be used as the feathers.

[0015] Next, the use form of the adsorbent may be various forms such as a solid form (including a film form), a powder form, and a liquid form. For example, the eggshell membrane may be used as it is as a membrane, or may be crushed into a powder. Further, the eggshell membrane with the eggshell can be pulverized and used as a solid or powder. Further, feathers or wool may be used in the form as it is (solid state), or may be cut into small pieces and made into a powder form. Alternatively, eggshell membranes, feathers, or wool can be dissolved in an alkaline solution and liquefied. For example, it has been confirmed by experiments that the eggshell membranes, feathers, or wool after completion of the above pretreatment are easily dissolved when immersed in a 30 wt% sodium hydroxide solution at room temperature for about 20 hours. The amount of dissolution in this experiment is about 5 g of the raw material of the organism with respect to 50 cc of the sodium hydroxide solution.

Next, a specific method of the wastewater treatment method of the present invention using the above-mentioned biological material as an adsorbent and a wastewater treatment apparatus used for the method will be described. In principle, the wastewater may be brought into contact with the adsorbent, but this contact system may take various forms. For example, there is a method in which the adsorbent is solidly charged and fixedly held in a channel or a chamber through which drainage passes. In this case, it is necessary to appropriately regenerate the loaded adsorbent using hydrochloric acid or the like. FIG.
FIG. 1 is a diagram showing an example of a wastewater treatment device employing this method. This device is an untreated wastewater W1 containing hexavalent Se.
Is introduced through an untreated wastewater introduction line 1, and a filling tower 4 into which pH-adjusted wastewater derived from the pH adjustment tank 2 is introduced via a pH-adjusted wastewater line 3, respectively. , 5, a treated wastewater deriving line 6 for deriving treated wastewater W2 from these filling towers 4, 5, and a pH adjusting solution supply line 7 for supplying a pH adjusting solution Y to the pH adjusting tank 2.
And regenerating liquid supply lines 8 and 9 for supplying the regenerating liquid Z to the filling towers 4 and 5, respectively, and a regenerating liquid deriving line 10 for discharging the regenerating liquid from the filling towers 4 and 5.

Although not shown, a sensor for detecting the pH in the pH adjusting tank 2 and a pH adjusting liquid supply line 7 based on the detected value of the sensor are provided as components of the control system. A controller that controls the opening of the flow control valve and maintains the pH in the pH control tank 2 within a certain range may be provided. In addition, an on-off valve or a flow path switching valve provided in each of the lines 3, 6, 8, 9, and 10 is controlled to automatically flow an appropriate regenerating solution to one of the filling towers 4 and 5. A controller may be provided. Here, the filling towers 4 and 5 are the adsorbents 4 made of the above-mentioned solid biological material.
Reference numerals a and 5a denote fixed-bed contact processing towers loaded and held. As the pH adjusting liquid Y, for example, sulfuric acid (H ₂
An aqueous solution of SO ₄ ) can be used as an alkali, for example, an aqueous solution of caustic soda (NaOH). In addition,
It is preferable to provide two pH adjustment liquid supply lines 7 for acid and alkali. Further, the pH value in the pH adjusting tank 2 is controlled to about 2 to 8, preferably 4 to 6. Also,
As the regenerating solution Z, a 1 to 2N aqueous hydrochloric acid solution can be used.

In the apparatus shown in FIG. 1, the pH of the untreated wastewater W1 is adjusted in the pH adjusting tank 2 and then guided to at least one of the filling tower 4 and the filling tower 5 to adsorb and remove Se and mercury. Drained line 6
Is discharged from Then, the regenerating solution Z is appropriately introduced into the filling tower 4 or the filling tower 5, and Se and mercury adsorbed on the adsorbent 4a or 5a are eluted into the regenerating liquid, and thus contain Se and mercury thus desorbed. The regeneration liquid is discharged from the regeneration liquid discharge line 10.

As a method for bringing the wastewater into contact with the above-mentioned adsorbent, a so-called flow-type reaction tank is used, and the adsorbent and untreated wastewater are continuously introduced into the same tank. There is a method of drawing out after mixing and performing solid-liquid separation. FIG.
FIG. 1 is a diagram showing an example of a wastewater treatment device employing this method. In this case, this device also realizes the removal of tetravalent Se, and is mainly composed of an adsorption treatment tank 21, an insolubilization treatment tank 22, a coagulation tank 23 (solid-liquid separation means), and a thickener 24 (solid-liquid separation means). Make up the configuration. The adsorption treatment tank 21 contains the adsorbent X
(Solid, powder, or liquid) and untreated wastewater W1
And a tank in which the pH adjusting liquid Y is continuously introduced and mixed by the stirrer 25. The tank 21 has a pH sensor 26 for detecting the pH of the processing solution in the tank, and a pH sensor 26
And a pH controller 27 for controlling the introduction amount of the pH adjusting solution Y in order to maintain the pH value of the processing solution in the tank within a predetermined range based on the detected value of

The insolubilization tank 22 is configured such that wastewater sufficiently mixed and stirred with the adsorbent X continuously flows in from the adsorption tank 21, and a treatment agent A (for example, FeCl ₃ or FeCl ₃ ) for insolubilizing tetravalent Se. Fe ₂ (SO ₄ ) ₃ ) and pH adjusting solution Y
Are continuously introduced and mixed and stirred by the stirrer 28. The tank 22 also has a pH sensor 29 for detecting the pH of the processing solution therein, and a pH adjusting solution Y for maintaining the pH value of the processing solution in the tank within a predetermined range based on the detection value of the pH sensor 29. A pH controller 30 for controlling the introduction amount is provided. The insolubilization tank 22
The pH value is preferably controlled to 5 to 9, preferably about 6 to 8, in order to promote the insolubilization of tetravalent Se while preventing the desorption of hexavalent Se from the adsorbent. The coagulation tank 23
The wastewater sufficiently mixed and stirred with the treating agent A is supplied to the insolubilizing treatment tank 2.
This is a tank in which the polymer coagulant B is continuously introduced and mixed and stirred by the stirrer 31. The polymer flocculant B binds fine solid particles by a so-called cross-linking phenomenon or the like, and facilitates sedimentation and separation in the thickener 24 described later. In this case, the thickener 24 is provided with a rake 32 for collecting mud, concentrates sludge S (solid content) in the drainage discharged from the coagulation tank 23, discharges the sludge S from the center of the bottom surface, and clarifies the liquid by overflow from the top. This is a known device from which (ie, post-treatment wastewater W2) is discharged.

In the apparatus shown in FIG. 2, hexavalent Se and mercury in the wastewater are adsorbed by the adsorbent in the adsorption treatment tank 21 having a predetermined pH value. Note that the adsorbent made of the above-mentioned biological material has a much lower adsorption capacity for tetravalent Se than hexavalent Se, as described later.
Are hardly adsorbed, and most of them remain dissolved in the liquid (that is, in the wastewater). And the insolubilization tank 2
2, the tetravalent Se in the wastewater causes a reaction represented by the following reaction formula (1), (2) or (3), (4) with the treating agent A to cause iron selenite (Fe ₂ (SeO) ₃ ) It becomes ₃ ) and becomes insoluble. FeCl ₃ → Fe ³⁺ + 3Cl ⁻ (1) 2Fe ³⁺ + 3SeO ₃ ^2- → Fe ₂ (SeO ₃ ) ₃ ↓ (2) or Fe ₂ (SO ₄ ) ₃ → 2Fe ³⁺ + 3SO ₄ ^2- (3 ) 2Fe ³⁺ + 3SeO ₃ ^2- → Fe ₂ (SeO ₃ ) ₃ ↓ (4)

Therefore, when the wastewater mixed with the adsorbent X and the like is separated into solid and liquid by the functions of the coagulation tank 23 and the thickener 24, the hexavalent Se, the tetravalent Se, the mercury in the wastewater, Most of the harmful substances contained in the sludge S are discharged as solids, and the concentration of these harmful substances in the wastewater is remarkably reduced. That is, hexavalent Se and mercury are mostly adsorbed by the adsorbent and are separated as solids together with the adsorbent. Even when a liquefied material is used as the form of the adsorbent, the liquefied biological material is made of hexavalent Se or mercury (H
Since it is precipitated on the solid phase side by binding to g), most of it is finally contained in the sludge S and discharged. In addition, tetravalent Se is also separated on the solid phase side as iron selenite by the above-described reaction, and is almost insolubilized and mixed into the sludge S.

According to the above-described wastewater treatment method or wastewater treatment apparatus, hexavalent Se, which could not be removed conventionally, is sufficiently removed from the wastewater, as demonstrated in the examples described below. The above-mentioned drainage standard (0.1 mg / l) can be easily cleared, and Hg can be effectively removed. For this reason, troublesome and costly treatment of diluting the wastewater with a large amount of water is not required, and compliance with the wastewater regulation on Se can be achieved easily and at low cost. Conventionally, when the desulfurization effluent contains Hg exceeding a regulated value, the Hg is led to an Hg chelate tower, and is adsorbed on a chelate resin loaded in the chelate tower. However, when a high concentration of Hg flows into a chelating resin for Hg, the adsorbing performance is reduced in a short period of time and the life is short. I was However, if the present invention is applied to the treatment of desulfurization effluent, Hg is also removed together with hexavalent Se by the adsorption action of the biological material, and the Hg chelate tower is not required, so that equipment costs and operation costs can be reduced.

The principle of adsorbing Se and Hg by the adsorbent composed of the above-mentioned biological material is not necessarily clear, but is considered as follows. In other words, proteins constituting eggshell membranes, feathers, wool, etc., have a cross-linking structure between molecules, are extremely stable chemically, and are composed of mesh-like fibers. Having. Also, this kind of protein has
NH or C = O in the peptide skeleton, NH ₃ or CO in the side chain
OH, OH, and SH groups are present, and due to their interaction, they exhibit the ability to adsorb various ions at an appropriate pH.

The form of the wastewater treatment apparatus used in the present invention is not limited to the above example, but may be various forms. For example, in the case of the method shown in FIG. 1, a larger number of filling towers (contact processing towers) may be provided according to the amount of wastewater to be treated. Further, the present invention is not limited to the fixed bed type, and a so-called fluidized bed type contact treatment tower can also be used. In the second method shown in FIG. 2, the insolubilization treatment tank 22 does not always need to be provided, and may be deleted when the concentration of tetravalent Se in the untreated wastewater W1 is low. Further, the solid-liquid separation means is not limited to the one comprising the coagulation tank and the thickener, for example, a so-called coagulation sedimentation apparatus in which the functions of the coagulation tank and the thickener are integrated, a filter of a belt filter, or a centrifugal sedimenter. May be used. Further, as shown in FIG. 3, a configuration in which the adsorption treatment tank 21 is provided on the downstream side of the insolubilization treatment layer 22 may be employed. Examples of the treating agent for insolubilizing tetravalent Se include, in addition to FeCl ₃ or Fe ₂ (SO ₄ ) ₃ , a chelating agent (for example, trade name: Miyoshi resin EPORAS MX-7).
Or a polymer heavy metal scavenger (for example, Miyoshi resin trade name:
Epofloc L-1) or the like can be used.

In the case where Hg is contained in the wastewater, the structure of the wastewater treatment method or wastewater treatment apparatus of the present invention (using the above-mentioned biological raw material) alone is not limited to Hg, as will be demonstrated in the experiments described later. Although it is sufficiently possible to satisfy the wastewater standard value, a conventional Hg chelate tower may be provided on the downstream side for emergency use. In this way, emergency situations are ensured, and Hg
The load on the chelating tower is remarkably reduced, and the life of the Hg chelating resin can be significantly prolonged.

[0027]

EXAMPLES The inventors of the present invention have conducted various experiments for verifying the above-mentioned operation and effect, which will be described below. <Experiment 1> In Experiment 1, as Comparative Example 1, a Se removal test using a chelating agent was performed. Here, a commercially available chelating agent in the wastewater containing tetravalent Se and hexavalent Se (chelating _{group: -NH-CS 2 H, -SH} ) with added so that the to 50 mg / l, the addition of NaOH At pH
By operating so as to be about 7, the effect of removing tetravalent Se and hexavalent Se was examined. Table 1 shows the results. Although tetravalent Se can be removed by the chelating agent, hexavalent Se is hardly removed, and it can be seen that the chelating agent has almost no effect on removing hexavalent Se.

[0028]

[Table 1]

<Experiment 2> Next, in Experiment 2, as a comparative example 2, a Se removal test using FeCl ₃ was performed. Here, 4
110 mg / Fe ^{3+ in} wastewater containing trivalent Se and hexavalent Se
Then, FeCl ₃ was added so that the pH became 1 and the pH was adjusted to about 7 with NaOH, and the effect of removing tetravalent Se and hexavalent Se was examined. Table 2 shows the results. FeCl ₃ is effective in removing tetravalent Se, but hardly exhibits the effect of removing hexavalent Se.

[0030]

[Table 2]

<Experiment 3> Next, in Experiment 3, as Example 1, eggshell membrane which is a raw material of a living organism was used, and 4
The adsorption removal test of valence Se and hexavalent Se was performed. The eggshell membrane is prepared by immersing the eggshell in a 5% HCl solution to elute calcium ions, which are metal ions constituting the eggshell, to obtain an eggshell membrane, followed by washing with 0.5N NaOH and distilled water to wash the eggshell. A membrane was made. Using this eggshell membrane, an adsorption removal test of tetravalent Se and hexavalent Se contained in the desulfurization wastewater was performed under the conditions shown in Table 3. The experiment was carried out at each pH by immersing the eggshell membrane in a container containing desulfurization drainage and stirring for a predetermined time, and analyzed the concentrations of tetravalent Se and hexavalent Se in the liquid.

[0032]

[Table 3]

FIG. 4 shows the results of this test (S for each pH value).
e) after treatment, ie, pH on the adsorption and removal performance of tetravalent Se and hexavalent Se by the eggshell membrane.
The effect of As is clear from these results, the eggshell membrane has a pH of about 2 to 8, preferably 4 to 6, in the range of Se.
It has the property of adsorbing and removing (tetravalent Se and hexavalent Se), but has particularly high adsorption removal performance for hexavalent Se. As described above, this hexavalent Se is difficult to remove with a normal chelating agent, FeCl _3, or the like. If hexavalent Se can be selectively treated by an eggshell membrane, the other tetravalent Se becomes FeCl _3.
It can be easily treated by adding a chelating agent or a combination thereof, and by combining these, it is possible to greatly reduce the total Se concentration and clear the wastewater standard of 0.1 mg / l with a large margin.

<Experiment 4> Next, in Experiment 4, as Example 2, hexavalent in desulfurization effluent was used in a flow-type reaction vessel using solid or liquid biological material such as eggshell membranes, feathers and wool. An Se removal test was performed. As for the preparation of a solid biological material, as for the eggshell membrane, as described above, the eggshell of a chicken is first immersed in a 5 wt% hydrochloric acid solution for about 10 hours to dissolve the eggshell mainly composed of calcium carbonate. Then, the remaining eggshell membranes are washed with distilled water to remove dust and the like, and after drying, washed with a 0.1N sodium hydroxide solution to remove egg whites and the like. A clean eggshell membrane is obtained. Next, the feather (in this case, chicken feather) or wool is washed with, for example, a 0.1N to 0.5N sodium hydroxide solution to remove oil and the like, and then washed with distilled water to complete the pretreatment. As described later, a clean feather or wool having a high adsorption ability of Se or Hg can be obtained. Next, a liquid biological material was prepared by dissolving the eggshell membrane, feather or wool that had been subjected to the above-mentioned pretreatment in a 30 wt% sodium hydroxide solution at room temperature for about 20 hours to be dissolved. In this case, the amount of dissolution is about 5 g of the raw material of the organism with respect to 50 cc of the sodium hydroxide solution.

In the experiment, the hexavalent Se concentration was 1.020 mg /
l of desulfurization effluent at 25 ° C. is continuously introduced into a reactor having an effective volume of 20 l at a flow rate of 20 l / hr,
With stirring. The concentration of the biological material (solid or liquid) in the reaction tank is 2 g / l in terms of solid matter.
In addition to the addition of the biological material, H ₂ SO ₄ or NaOH
Was added, and a hexavalent Se removal test was performed. The wastewater discharged from the reaction tank was sampled, filtered through a 1 μm glass filter, and hexavalent Se in the filtrate was analyzed by a Se hydride-ICP analysis method. Table 4 shows the results. Hexavalent Se in wastewater, which had been difficult to remove in the past, has a pH
Particularly in the range of 4 to 6, it was significantly removed.

[0036]

[Table 4]

<Experiment 5> Next, in Experiment 5, the performance of removing mercury Hg from the above-mentioned raw material for living organisms was demonstrated. That is, eggshell membranes,
The biological raw material of feathers and wool is very effective not only for selectively adsorbing and removing hexavalent Se but also for adsorbing and removing mercury Hg. Here, the eggshell membrane is immersed in the wastewater,
An Hg removal test was performed. The results are shown in FIG. 5 and the test conditions are shown in Table 5. The Hg concentration in the raw wastewater was 1.04 mg / l.
After 3 hours, the effluent standard value becomes 0.005 mg / l or less, and the biological material of the eggshell membrane is very effective in removing Hg.

[0038]

[Table 5]

[0039]

According to the wastewater treatment method of the first aspect,
By contacting the wastewater with an adsorbent composed of at least one biological material selected from eggshell membranes, feathers and wool, at least hexavalent Se in the wastewater is removed. This makes it possible to effectively remove hexavalent Se, which has been difficult in the past, and eliminates the need for complicated and costly treatment such as diluting the wastewater with a large amount of water. The Se concentration can be easily reduced to a regulated value or less at a low cost.

According to the wastewater treatment method of the present invention, the pH of the treatment liquid containing wastewater is adjusted to 2 to 8, preferably 4 to 6, during the removal treatment. PH of processing solution is 4-6
In this case, the action of removing hexavalent Se is remarkable, and even if the wastewater contains a large amount of hexavalent Se, the concentration of the wastewater can be reduced to the regulation value or lower at a lower cost with a smaller facility.

According to the third aspect of the present invention, the biological material is used as the adsorbent in a solid state. This simplifies the work of processing the raw material to obtain the adsorbent.

According to a fourth aspect of the present invention, as the adsorbent, a powder or liquid of the biological material is used. For this reason, storage and transportation of adsorbents,
Alternatively, handling such as supply to the apparatus becomes easy.

According to a fifth aspect of the present invention, there is provided a fixed-bed type contact treatment in which an adsorbent comprising at least one biological material selected from eggshell membranes, feathers and wool is fixedly loaded. At the tower, the adsorbent comes into contact with the waste water, and hexavalent Se that could not be removed conventionally is removed from the waste water. For this reason, the concentration of hexavalent Se in the wastewater can be reduced to a regulated value or less without requiring a troublesome and costly treatment such as diluting the wastewater with a large amount of water.

According to the wastewater treatment apparatus of the sixth aspect, the adsorbent composed of at least one biological material selected from eggshell membranes, feathers and wool, and the wastewater to be treated are adsorbed treatment tanks. , Wastewater and the adsorbent come into contact with each other, and hexavalent Se, which could not be removed from the wastewater, is adsorbed by the adsorbent. And 6
The adsorbent that has adsorbed the valence Se is separated and removed from the wastewater as a solid by the solid-liquid separation means. For this reason,
The hexavalent Se concentration in the wastewater can be reduced to a regulated value or less without the need for complicated and costly treatment such as diluting the wastewater with a large amount of water.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first example of a wastewater treatment apparatus that performs a wastewater treatment method of the present invention.

FIG. 2 is a diagram showing a second example of a wastewater treatment apparatus that performs the wastewater treatment method of the present invention.

FIG. 3 is a diagram showing a third example of a wastewater treatment apparatus that performs the wastewater treatment method of the present invention.

FIG. 4 is a view showing the results of Experiment 3 which demonstrates the Se removal effect of the wastewater treatment method of the present invention.

FIG. 5 is a view showing the results of Experiment 5 which demonstrates the Hg removal effect of the wastewater treatment method of the present invention.

[Explanation of symbols]

 4,5 Filling tower (contact processing tower) 4a, 5a Adsorbent 21 Adsorption treatment tank 23 Coagulation tank (solid-liquid separation means) 24 Thickener (solid-liquid separation means) W1 Untreated wastewater W2 Treated wastewater X Adsorbent Y pH adjustment liquid

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Kaneko 4-22, Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Tatsuyuki Kinoshita Kannon-Shimmachi 4 in Nishi-ku, Hiroshima-shi, Hiroshima No. 6-22, Mitsubishi Heavy Industries, Ltd., Hiroshima Research Laboratory (72) Inventor Susumu Okino 4-6-22, Kannon Shinmachi, Nishi-ku, Hiroshima, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd., Hiroshima Research Laboratory (72) Inventor Takashi Haruki, Hiroshima, Hiroshima, Japan Mitsubishi Heavy Industries, Ltd.Hiroshima Research Laboratory 4-72 Kanon Shinmachi, Nishi-ku (72) Inventor Kazuaki Kimura 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Heavy Industries, Ltd. (72) Inventor Eiji Ochi Tokyo 2-5-1 Marunouchi, Chiyoda-ku Mitsubishi Heavy Industries, Ltd. (56) References JP-A-7-24207 (JP, A) 51-141969 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/28 C02F 1/58 B01D 15/00-15/08 B01J 20/00-20/34

Claims (6)

(57) [Claims] The wastewater is contacted with an adsorbent composed of at least one biological material selected from eggshell membranes, feathers and wool, thereby producing at least hexavalent Se in the wastewater.
A wastewater treatment method characterized by removing water. 2. The wastewater treatment method according to claim 1, wherein the pH of the treatment liquid containing wastewater is adjusted to 2 to 8 during the removal treatment. 3. The method according to claim 1, wherein the biological material is used as the adsorbent in a solid state.
Wastewater treatment method as described. 4. The wastewater treatment method according to claim 1, wherein the adsorbent is obtained by converting the biological material into a powder or a liquid. 5. A wastewater treatment apparatus for removing at least hexavalent Se from wastewater, wherein an adsorbent comprising at least one biological material selected from eggshell membranes, feathers and wool is loaded in a fixed state. And a fixed-floor contact treatment tower, through which the wastewater to be treated passes. 6. A wastewater treatment apparatus for removing at least hexavalent Se from wastewater, which is to be treated with an adsorbent comprising at least one biological material selected from eggshell membranes, feathers and wool. And a solid-liquid separation means for removing solids from wastewater containing the adsorbent derived from the adsorption treatment tank. Wastewater treatment equipment.