WO2004058423A1

WO2004058423A1 - Method for removing heavy metal in incineration ash

Info

Publication number: WO2004058423A1
Application number: PCT/JP2003/016784
Authority: WO
Inventors: Hiroshi Nakao; Hironori Suzuki; Masataka Usui; Yasuo Nomura
Original assignee: Kowa Co., Ltd.
Priority date: 2002-12-26
Filing date: 2003-12-25
Publication date: 2004-07-15
Also published as: CA2509108A1; KR20050086484A; CN1732053A; CN100540162C; KR101080894B1; JP2004202449A; JPWO2004058423A1; AU2003292829A1; CA2509108C

Abstract

A method for removing a heavy metal in an incineration ash, characterized in that it comprises contacting an incineration ash from an industrial waste with water to form an aqueous solution containing a heavy metal, and contacting the aqueous solution with a heavy metal absorbing agent. The method allows the removal of heavy metals in an incineration ash in a simple and easy way with good efficiency and the promotion of the reuse of the incineration ash.

Description

Method of removing heavy metals from incinerated ash

The present invention relates to a method for easily and efficiently removing heavy metals from incinerated ash of industrial waste. Background art

Environmental pollution from heavy metals such as cadmium, copper, zinc, chromium, and lead is a problem worldwide because it is toxic to living organisms at trace levels. On the other hand, industrial waste such as urban garbage and industrial garbage is usually incinerated at incineration plants and discarded. If the incinerated ash contains heavy metals, they are transported to the final disposal site and disposed of. The incinerated ash containing heavy metals is simply transported to the final disposal site and is not reused at all. Disclosure of the invention

Therefore, an object of the present invention is to provide a method for easily and efficiently removing heavy metals in incinerated ash and promoting the reuse of incinerated ash.

Therefore, the present inventor conducted various studies on means for removing heavy metals from incinerated ash, and it was not possible to remove only heavy metals from incinerated ash by the coagulation sedimentation method (see Fig. 1), which is a conventional method for removing heavy metals. However, if the heavy metals in the incinerated ash are transferred into the aqueous solution and the aqueous solution is brought into contact with the heavy metal adsorbent, the heavy metals in the incinerated ash can be easily and efficiently removed, and the incinerated ash can be used as a raw material for cement, etc. And completed the present invention.

That is, the present invention relates to a heavy metal-containing material produced by contacting incinerated ash of industrial waste with water. It is intended to provide a method for removing heavy metals from incinerated ash, which comprises contacting an aqueous solution with a heavy metal adsorbent.

ADVANTAGE OF THE INVENTION According to this invention, the heavy metal in incineration ash can be removed simply and efficiently by contacting the heavy metal-containing aqueous solution produced by contacting the incineration ash of industrial waste with water with the heavy metal adsorbent. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a diagram showing an example of a current industrial waste incineration facility.

FIG. 2 is a diagram showing an example of an apparatus in which a heavy metal adsorbent is installed in an industrial waste incineration facility. .

FIG. 3 is a diagram showing an example of a heavy metal adsorbent section of a batch system provided with a stirrer.

FIG. 4 is a diagram showing the results of an adsorption and elution test of Cu KR-102 strain on Cu. FIG. 5 is a graph showing the results of an adsorption and dissolution test of strain KR I-0.2 on Ni. FIG. 6 is a graph showing the adsorbing ability of Teflon-containing microbial cell beads for Cu (first and tenth rounds).

FIG. 7 is a graph showing the adsorption capacity (first time and tenth time) of the Teflon-containing microbial cell beads for Zn.

FIG. 8 is a graph showing the adsorption ability of heat-treated bacterial beads on Cu.

FIG. 9 is a diagram showing the adsorption ability of heat-treated bacterial beads on Zn.

FIG. 10 is a graph showing the adsorption ability of heat-treated microbial cell beads for Cu (first time and tenth time).

FIG. 11 is a diagram showing the adsorption capacity (first and tenth times) of the heat-treated microbial cell beads for Zn.

FIG. 12 is a diagram showing the relationship between the amount of added bacterial cell beads and the ability to adsorb Zn. FIG. 13 is a diagram showing the relationship between the number of regenerating bacterial peas and the ability to adsorb Zn. BEST MODE FOR CARRYING OUT THE INVENTION

The incinerated ash of industrial waste used in the present invention is used for industrial waste such as municipal waste, industrial waste, paper, flammable plastic, wood waste, textile waste, rubber waste, metal waste, sludge, waste oil, waste acid, waste aluminum waste, etc. Waste incineration ash. As shown in Fig. 1, industrial waste incineration plants usually incinerate industrial waste in a kiln, and the incinerated ash is introduced into cooling water and treated as a slurry. If the incinerated ash contains heavy metals, this slurry is disposed of at the final disposal site.

In the present invention, the heavy metal-containing incineration ash is brought into contact with water to generate a heavy metal-containing aqueous solution. Heavy metals such as Ag, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Pd, and Zn can form hydroxides in the basic region. , Settle. Therefore, it is necessary to make water acidic in order to generate a heavy metal aqueous solution. That is, in order to contact the incineration ash with water to produce a heavy metal-containing aqueous solution, after contacting the incineration ash with water, adjust the pH of the water to an acidic side, or adjust the pH of the water to an acidic side. May be brought into contact with the incineration ash. The pH is preferably between 4 and 8, especially between 5 and 7. To adjust the pH, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as citric acid, oxalic acid, and acetic acid may be added to water.

The obtained heavy metal-containing aqueous solution is brought into contact with a heavy metal adsorbent to remove heavy metals. Examples of the heavy metal adsorbent used include a biomass-derived heavy metal adsorbent, an ion exchange resin, a chelate resin, activated carbon, and an electrolyte gel. Examples of the biomass-derived heavy metal adsorbent include microorganisms such as bacteria, molds, and yeasts, seaweeds, and dead cells thereof. The biomass-derived heavy metal adsorbent is preferably a dead cell obtained by acid-treating a microorganism. Among these, the dead microorganisms include heavy metal-adsorbing dead microorganisms as described in Biotechnol. Prog. 1995, 11, 235-250, such as Bacillus, Candida, Cladosporium, and Rhizopus. , Saccharomyces, Pichia, Senedesmus, Penicillium, Aspergillus, Trichoderma Heavy metal-adsorbing microbial dead cells belonging to the genus, Ascophyllum, Fucus, Absididia, Staphylococcus, etc. are preferable, and microbial dead cells obtained by acid-treating these are more preferable. Among them, cells obtained by acid-treating a bacterium selected from Bacillus sp. KR I-02 or a related bacterium, Bacillus' licheniformis and Staphylococcus sp. The acid treatment is particularly preferable because the acid treatment does not significantly reduce the weight of the bacterial cells and increases the amount of heavy metal adsorbed per unit weight of the bacterial cells, as compared with the case of re-treatment. Among Bacillus licheniformis, Bacillus licheniformis KR 1-03 (FERM BP-8167) and related strains are particularly preferred. Staphylococcus sp. KR I-04 or its relatives, Staphylococcus sp. KR I-04 (FERM

BP-8166) and its relatives are particularly preferred. Here, the term “related strain” refers to a strain belonging to the same species as the strain and having the same heavy metal adsorption ability as the strain. The acid used for the acid treatment of these bacteria is not particularly limited as long as they can kill these bacteria. Inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid; acetic acid, formic acid, valeric acid, and propionic acid And organic acids such as oxalic acid and citric acid. The acid treatment may be performed under conditions that kill the bacteria. For example, it is preferable to treat the bacteria with an aqueous solution of an acid having a pH of 5-2 for 15 to 150 minutes. The temperature at the time of the acid treatment is preferably the growth temperature of the bacteria. Preferably, the bacteria are washed with water before the acid treatment. The cells after the acid treatment are preferably washed with water to return the pH to neutral. The acid-treated microbial cells may be used as a suspension in water or the like, but are preferably used after drying by means such as freeze-drying, spray-drying, and heating.

The acid-treated cells obtained showed a very small decrease in cell weight as compared to the cells treated with Arikari, and the ability to adsorb heavy metals was increased as compared to untreated cells. Therefore, the acid-treated cells are particularly useful as a heavy metal adsorbent as compared with untreated viable cells and alkali-treated cells.

In addition, as the ion exchange resin, a cation exchange resin, specifically, a strongly acidic cation Exchange resins and weakly acidic cation exchange resins. Examples of the chelating resin include resins having a chelating group such as an iminodiacetic acid group, a polyamine group, an N-methyldalcamine group, an amidoxime group, an aminophosphoric acid group, a dithiolrubamic acid group, and a thiourea group. Examples of the electrolyte gel include an electrolyte gel having a hydroxyl group, an amino group, a hydroxyl group and the like and having a metal binding ability.

These heavy metal adsorbents preferably have a form containing a solid carrier. Examples of the solid carrier include various inorganic carriers and resin carriers.

Examples of the inorganic carrier for immobilizing the heavy metal adsorbent include silica gel, alumina, glass, diatomaceous earth, and Teflon (registered trademark). Examples of the resin carrier include cellulose, acrylamide derivatives, polysulfone, polyvinyl alcohol, polystyrene, calcium alginate, lagenin, polyethyleneimine, and the like. These inorganic carriers and resin carriers can be used alone or in combination.

The microorganism-killed cells typified by acid-treated cells are preferably used in the form of microbeads supported on the inorganic carrier or resin carrier. Of these, bacterial beads in which dead bacterial cells are supported on the resin carrier are particularly preferred. The weight ratio of dead cells in the microbeads to the inorganic carrier or resin carrier is preferably 1:10 to: L0: 1, more preferably 1: 5 to 5: 1.

The method for producing microbial beads is a method of dropping a mixture of dead cells and the carrier and a medium such as liquid nitrogen (dropping method); using a nucleus of lactose or the like; And a method of granulating the mixture by spraying a mixture of the above and a carrier (granulation method). The microbeads obtained by this granulation method can improve the water resistance by heat treatment. In addition, it can be made porous by freeze-thaw treatment to improve the heavy metal adsorption power. Here, the heat treatment is performed at 120 to 250 ° C. for 2 to 30 minutes, particularly 150 to 200 ° C. (: For 5 minutes to 30 minutes.

When the bacterial beads aggregate during the heavy metal adsorption treatment, the contact efficiency with heavy metals decreases. Therefore, it is preferable to suppress aggregation of the bacterial beads. As the aggregation suppressing technique, it is preferable to add an additive such as Teflon powder, dibutyl phthalate, castor oil, and ethyl acetate, in addition to the dead cells and the resin when preparing the microbial cell beads. These additives are preferably used in an amount of 0.05 to 5 times, more preferably 0.1 to 2 times the weight of the dead cells. Aggregation can also be suppressed by heat-treating the bacterial beads. Here, the heat treatment conditions are the same as the conditions for improving the water resistance.

Means for bringing the heavy metal-containing aqueous solution into contact with the heavy metal adsorbent include a method of continuously bringing the heavy metal-containing aqueous solution into contact with the heavy metal adsorbent (see FIG. 2), a method of performing a batch treatment (see FIG. 3), and the like. In the batch processing method, it is desirable to provide a stirrer to enhance the effect of adsorbing heavy metals.

Thus, heavy metals in the incineration ash are removed. The adsorbed heavy metal is easily eluted from the heavy metal adsorbent by lowering the pH by adding an organic acid or an inorganic acid, or by adding a chelating agent such as EGTA or EDTA, so that the heavy metal can be recovered. Example

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (Selection and identification of heavy metal-adsorbing bacteria)

(1) Selection of heavy metal adsorption bacteria

The soil was suspended in physiological saline and allowed to stand, and the supernatant was inoculated on a Brain Heart Infusion Agar medium containing heavy metals of ImM, and colonies that appeared one day later were selected.

(2) Identification of the obtained strain

a. Method

As a first-stage bacterial test, cell morphology, gram staining, presence of spores, and flagellar motility were observed with a light microscope U-LH1000 (Olympus, Japan). Brain Heart Infusion Agar (Bee ton Dickinson, NJ, US A) + agar medium (B. H. I agar) was observed for colony morphology. Tests were conducted on catalase reaction, oxidase reaction, acid / gas production from glucose, and oxidized Z-fermentation (OZF) of glucose.

As a second-stage bacterial test, a biochemical property test was conducted using the API system (bioMrieux, France: http: // www. Biomerieux. Fr / home_en.htm) according to the measurement method.

In addition, a physiological property test was performed as an additional test.

b. Results

Table 1 shows the results of the first stage test.

table 1

+: Positive,-: negative, w: weak response

Tables 2 to 4 show the results of the second stage test and the additional test. Table 2

(K R 1-0 2)

Control one glycerol + erythritol one

D-arabinose-L-arabinose + report +

D-xylose-1 L-xylose-1 aditol-β-methyl-D-xylosegalactose 1 glucose + fruc I ^ ice + mannose + sorbose-1

Rhamnose-Dulcitol-Inositol-

Mannitol + sorbitol + α-methyl-D-mannose enzyme

Α-methyl-D-glucose N-acetylglucosamine

The Amygdalin One

Yes +

,, ヽ Arbutin-esculin + salicin +

Cellobiose + Mal! Su + Lactose-

Melibiose-I White sugar + Treppers-I

Inulin one meletitose one roughinose one

Starch-glycogen + xylitol

Gentiobiose-D-llanoose-1 D-Lyxose-1

D-Evening Gateau D-Fucose-L-Fucose 1

D-arabitol one L-arabitol one darconate one

2-ketodalconic acid 1 5-ketogluconic acid 1

iS-Galactosidase-1 Arginine dihydrolase-1

Raw

Lysine orditin decarboxylase

Utilization of citrate-―S production

Urease-tributane deaminase test

Indole production-acetoin production +

Vilatinase + nitrate reduction +

Viability at 50 ° C +

Growth in remorse

Mouth Viability in 10% NaCl +

Hippurate hydrolyzable I

Casein hydrolyzable +

Table 3 (KR 1 -03)

Table 4

(KR 1 -04)

Based on the above results, KR I-02 belongs to the genus Bacillus, but the species could not be identified. Therefore, this fungus was named Bacillus sp. KR 1-02. In addition, KR I-03 was determined to belong to Bacillus licheniformis, and was named Bacillus licheniformis KR 1-03. Also, KR I-04 belongs to the genus Staphylococcus, but did not lead to the identification of the bacterial species. Therefore, this bacterium was named Staphylococcus sp. KR I-04. KR I_02 as FERM BP-8165, KR I-03 as FERM BP-8167, KR I_04 as FERM BP-8166, respectively, dated August 21, 2002, east of Tsukuba, Ibaraki, Japan 1-1 chome 1 Chuo No. 6 (zip code 305-8516) Deposited at the Patented Microorganisms Depositary, National Institute of Advanced Industrial Science and Technology. Example 2

KR I-02, KR I-03, and KR I_04 were cultured in Brain Heart Infusin medium (Difco), washed with water, and suspended by adding 0.5 times the wet weight of 0.5 N hydrochloric acid. Thereafter, the bacteria containing hydrochloric acid were shaken at 37 ° C for 2 hours. We also compared the method of Brierley et al. (USP 4, 992, 179). That is, wet Bacteria to which 5% by weight of 3% sodium hydroxide had been added were shaken at 50 ° C. or 100 ° C. for 10 minutes. After shaking, all bacteria were thoroughly washed with water and lyophilized. As a result, as shown in Table 5, the weight was reduced by only about 20% in the acid treatment compared with the case of washing with water (untreated), but decreased by more than 50% in the sodium hydroxide treatment. In particular, when the treatment was performed at 100 ° C., the value decreased by 60% or more.

Table 5

Example 3 (Measurement of metal adsorption amount)

Bacterial powder obtained by freeze-drying was dispersed in a buffer solution (Tris: 100) to prepare a suspension of 6 OmgZmL. Tris (1 OmM) 2. was stirred bacterial suspension 4mM heavy metal aqueous solution prepared in _{_{_{(CdCl 2 CuS0 4 ZnCl 2 NiCl}}} 2) 1 mL 2 0 ^ L put 2 hours using. After the completion of the reaction, the concentration of heavy metals in the supernatant separated by centrifugation was measured using an atomic absorption spectrophotometer.

The results are shown in Table 69. The amounts of cadmium and copper adsorbed by KR 1-02 KR I- 03 KR I_04 were increased by acid treatment compared to water washing. The amount of cadmium adsorbed by sodium hydroxide treatment also increased with KR I-0.2 KR I_03 KR I- 04, but the acid treatment was larger than the sodium hydroxide treatment. The amount of adsorption of zinc and nickel is KR 1-0 2 KR I-0 3 KR I-04 The amount increased by the acid treatment compared to that of the acid treatment, but the uptake was slightly higher in the sodium hydroxide treatment (100 ° C). When comparing the uptake of heavy metals by the treatment of sodium hydroxide at 50 ° C and 100 ° C, the amount of adsorption increased at 100 ° C than at 50 ° C.

Table 6

Table 7

Table 8

Table 9

(Amount of nickel adsorbed mol / g)

Processing method

KRI-02 KRI-03 KRI-04

Unprocessed 10.2 42.1 37.1

Acid treatment 392.3 318.5 330.1

50 at 244.2 293.7 252.1

Hydroxy sodium

100 ° C 407.0 335.7 322.3 Example 4 (Adsorption and dissolution test)

Lyophilized bacteria (KR I-02) were dispersed in 100 mM Tris buffer (pH 7.5) to prepare a suspension (6 Omg / mL). The bacterium suspension 20 L, Tr is (1 OmM ) heavy metal aqueous solution prepared in 4 mM 2. with (CuS0 _4, NiCl ₂₎ was added to lmL was stirred for 2 hours (respectively pH 6. 0 and pH 7. 3) After the reaction was completed, centrifugation was performed to separate the supernatant (a) and the bacterial layer. Hydrochloric acid (Hl. 54) was added to the bacterial layer, stirred for 30 minutes, and centrifuged again to separate the supernatant (b) and the bacterial layer. The concentration of heavy metals in the supernatants (a) and (b) was measured using an atomic absorption spectrophotometer, and the amounts of adsorption and desorption were calculated. The bacterial layer after the treatment with hydrochloric acid was washed in 10 OmM Tris (pH 7.5) to return the pH to neutral, and the adsorption / desorption experiment of heavy metals was repeated (three times). The results are shown in FIGS. For all metals, the amount of adsorption in the second time decreased compared to the first time, but the second and third times showed almost the same amount of adsorption. In the case of Cu, the desorption amount showed a good value of 90% or more of the adsorption amount. In the case of Ni, the first time was small, but the second and third times showed almost the same value as the adsorption amount, indicating that any metal can be reused. · Example 5

Synthesis of bacterial beads containing additives

To a 10% (w / v) aqueous solution of polyvinyl alcohol (PVA) (polymerization degree: 1500 to 1800, 98% in value) was added KR1-02 and additives of the same weight as PVA and the mixture was stirred. The suspension prepared in liquid nitrogen was dropped with a syringe, followed by freeze-thawing and freeze-drying. Teflon powder, castor oil, ethyl acetate, and dibutyl phthalate were used as additives.

Example 6

Evaluation of cohesiveness of bacterial beads containing additives

Using 20 mL of ash cooling water (pH 7.5) from an incineration plant that contains a large excess of alkali metals and alkaline earth metals with respect to heavy metals (cadmium, copper, zinc, nickel). The cohesiveness (stability) of the gel beads (0.35 g) was examined. After shaking for 12 hours, the adhesion and aggregation of the gel were visually observed. As a result, it was confirmed that flocculants were aggregated in the cell beads without addition. The additive-containing microbial bead, which is a mixture of teflon powder and dibutyl phthalate as additives, had the highest effect of suppressing aggregation. Castor oil and ethyl acetate were moderately effective.

Example 7

Effect of additive mixing ratio on aggregation

In order to examine the effect of aggregation on the mixing ratio (weight ratio) of the additive and KR I-02, Teflon-mixed bacterial cell beads were prepared. The cohesiveness (stability) of the beads (0.35 g) was examined using 20 mL of ash cooling water (pH 7.5) in the same manner as in Example 6. As a result, it was suggested that beads not mixed with bacterial cells (KR I-02) aggregated, but aggregation was suppressed by increasing the ratio of components other than PVA (Table 10).

Table 10

Effect of mixing ratio on aggregation

〇, ◎: Not aggregated X: Aggregated △: Slightly aggregated

Example 8

Adsorption capacity of bacterial beads containing teflon

Teflon-containing microbial cell beads (weight ratio: Teflon: PVA: microbial cells (KPI-02) = 1: 1: 2) were prepared. After adsorption test with 20 mL of ash cooling water (pH 7.5), oxalic acid 20 mL (pH 1. 2) was added to perform a dissolution test. This adsorption / regeneration process was repeated, and changes in the adsorption capacity were observed. The first adsorption capacity and the number of uses 10 times were compared. The adsorption capacity of heavy metals (copper and zinc) was hardly reduced even after 10 uses. In addition, it was able to be adsorbed and removed with little effect of high concentration of coexisting salt. (Figures 6 and 7).

Example 9

Effect on aggregation and adsorption of heat treated beads

Gel beads mixed with KR 1-02 (weight ratio PVA: cells = 1: 2) by the method described above were prepared, freeze-dried and heat-treated (180 ° C) for 10 minutes. In the same manner as above, the cohesiveness (stability) of the gel beads (0.35 g) in 20 mL of ash cooling water (pH 7.5) was examined. Furthermore, in order to investigate the change in adsorption capacity due to the heat treatment, the concentration changes of heavy metals (zinc, nickel) and alkaline earth metals (calcium, magnesium) in the ash cooling water were measured with an atomic absorption spectrophotometer. 'Comparison of the heat-treated and non-heat-treated microbeads showed that the heat-treated microbeads were inhibited from agglomeration and no adhesion of particles was observed. On the other hand, agglomeration was confirmed in the non-heat treatment in the same manner as described above. Also, from the change in the concentration of each metal in the ash cooling water, almost no decrease in adsorption capacity before and after heat treatment was observed (Figures 8 and 9).

Example 10

Change in adsorption capacity of heat treated beads

After the adsorption test of the heat-treated beads described above, the beads were separated, and 20 mL of oxalic acid (pH 1.2) was added to perform a dissolution test of each metal. After that, it was washed with Tris (10 OmM) and the adsorption test was performed again. This series of operations (the number of uses) was repeated, and the change in the adsorption capacity of the beads due to the regeneration was examined. The first adsorption capacity was compared with the tenth use adsorption capacity. As a result, the adsorption capacity of heavy metals (copper and zinc) was hardly reduced even when the number of uses was 10 times. In addition, it was able to be adsorbed and removed with little effect from coexisting high-concentration salts (Figures 10 and 11).

Example 11

Preparation of microbeads by granulation method

1 KR I-02 and PVA (Polymerization degree 98-99%) powder crushed to 50 m or less are mixed at a weight ratio of 2 to 1 to obtain a mixed powder. The granulation was performed using a granulating device. That is, spherical granules (lactose) were used as core particles (500 lim), and the mixed powder was sprayed and granulated while spraying an aqueous PVA solution (5%). The granulated particles were heat-dried (70 ° C), sieved to separate particles having a diameter of 1.4 to 1.7, and then heat-treated at 180 ° C for 20 minutes.

Example 12

Evaluation of water resistance of bacterial beads by granulation method

Heat-treated microbeads or unheated microbeads (0.35 g) were placed in water (20 mL) at 180 ° C. for 20 minutes and shaken for 24 hours. As a result, the particles of the non-heat treated microbeads collapsed and suspended in a few hours after shaking, but the shape of the heat treated microbeads maintained the particles even after 24 hours. From this, it was confirmed that heat treatment of the granulated microbeads can stably immobilize the microbes while maintaining the particle shape.

Example 13

Making the beads porous by the freezing method

The heat-treated microbeads obtained in Example 11 were immersed in water, washed, freeze-thawed in a state where water was sufficiently contained, and freeze-dried. The frozen beads (0.5 g) were added to zinc-containing wastewater (20 mL) and stirred, and the time dependence of zinc concentration was examined from the beginning of the reaction. As control, microbial cell beads that had only been heat treated were used. As a result, the change in the concentration of the microbeads subjected to the freezing operation was larger than that of the control. The zinc concentrations in the waste liquid after freeze drying and freeze thawing after 90 minutes were 354.1 M and 332.8, respectively, which were smaller than the control concentration of 381.6 M. Therefore, when the heat-treated microbeads are frozen, it is possible to rapidly diffuse heavy metals in the beads and to reduce the liquid phase concentration rapidly.

Example 14

Removal of heavy metals by beads

After immersion in 1N hydrochloric acid, heat-treated microbial beads washed with MES buffer (pH 6) Example 11) was placed in zinc-containing plating wastewater and stirred. Changes in zinc concentration were examined by changing the amount of bacterial cell beads (8, 17.5, 25, 35 mg / mL). Figure 12 shows the results. The change in zinc concentration was dependent on the amount of microbial beads, and the higher the amount of bead added, the greater the initial gradient of the concentration change. Therefore, zinc can be removed by adding microbeads to wastewater containing heavy metals such as zinc, and the zinc can be removed below the wastewater standard (75.6 M). These microbeads can adsorb and remove harmful heavy metals such as copper, iron, cadmium and nickel, in addition to zinc. Example 15

Regeneration of beads

The heat-treated microbial cell beads (Example 11, 0.35 g) were washed with a MES buffer (pH 6), added to zinc waste water (20 mL), and stirred. After the completion of the adsorption reaction, the bacterial cell beads were removed from the waste liquid, and placed in 1N hydrochloric acid (2 OmL) to remove heavy metals. After that, it was washed with MES and the wastewater was replaced again. This series of adsorption / desorption operations was repeated to regenerate the beads. Heavy metal concentrations were measured with an atomic absorption spectrophotometer. Figure 13 shows the relationship between the zinc adsorption (PH7) and the number of regenerations. The average initial concentration at each measurement was 790 M / iM for zinc and 458 M for iron. The average adsorption amount per g of dry weight (cell beads) was 36.2 mo 1 Zg for zinc and 4.6 AimolZg for iron. The number of times of regeneration was repeated 100 times, but the cell beads maintained their shape, and the amount of P deposited hardly changed. In addition, as a result of examining the amount of desorption with respect to P, desorption was observed at a rate of 90% or more. Therefore, it was confirmed that the microbeads are durable against a sudden change in pH and can be used repeatedly.

Example 16

As shown in Fig. 2, a pH regulator input section and heavy metal adsorbent section were installed in an industrial waste incineration facility, incinerated ash generated in the kiln was injected into cooling water, and the pH was adjusted to 5 to 6, Pass the cooling water through the heavy metal adsorbent section or, preferably, a batch system equipped with a stirrer. By treating with a system (Fig. 3), heavy metals in the aqueous phase can be easily and efficiently removed. Here, the dead microorganism cells and the microbeads obtained in Examples 2 to 15 can be used as the heavy metal adsorbent.

Claims

The scope of the claims

1. A method for removing heavy metals from incinerated ash, comprising contacting an aqueous solution containing heavy metals, which is produced by contacting incinerated ash of industrial waste with water, to a heavy metal adsorbent.

2. The method for removing heavy metals according to claim 1, wherein the heavy metal adsorbent is selected from a biomass-derived heavy metal adsorbent, an ion exchange resin and a chelate resin.

3. The method for removing heavy metals according to claim 1, wherein the heavy metal adsorbent is a microorganism-killed cell.

4. The method for removing heavy metals according to claim 1, wherein the heavy metal adsorbent is dead cells obtained by acid-treating a microorganism.

5. The method for removing heavy metals according to claim 3 or 4, wherein the microorganism-killed cells are supported on an inorganic carrier or a resin carrier.

6. The method for removing heavy metals according to claim 3, wherein the microorganism-killed cells are microbeads supported on an inorganic carrier or a resin carrier.

7. The method for removing heavy metals according to claim 6, wherein the bacterial cell beads contain Teflon powder, dibutyl phthalate, castor oil or ethyl acetate in addition to the carrier.

8. The method for removing heavy metals according to claim 6, wherein the cell beads are obtained by a granulation method.

9. The means of contacting the incineration ash with water to produce a heavy metal-containing aqueous solution is a method of contacting water with the incineration ash and then adjusting the pH of the water to the acidic side or incinerating the water with the pH adjusted to the acidic side. The heavy metal removal method according to any one of claims 1 to 8, wherein the method is to contact ash.

10. The method for removing heavy metals according to any one of claims 1 to 8, wherein the pH of the aqueous solution after contacting the incineration ash with water is adjusted to 4 to 8.

11. The weight according to any one of claims 1 to 10, wherein the heavy metal-containing aqueous solution is in continuous contact with the heavy metal adsorbent or in contact with the heavy metal adsorbent in a batch process. Metal removal method.