JP5939513B2 - Waste liquid treatment method containing heavy metals - Google Patents

Description

The present invention relates to heavy metal-containing waste liquid treatment how, more particularly, it relates to good heavy metal-containing wastewater treatment how it is possible to remove heavy metals in the waste at low cost.

  Conventionally, heavy metals discharged as harmful substances mainly include cadmium, lead, mercury, hexavalent chromium, arsenic, selenium, and the like, and these are designated as harmful substances in the Water Pollution Control Law. In addition to these, there are concerns about contamination with many types of heavy metals, and various treatment methods for their removal have been studied. Among these, especially hexavalent chromium is considered difficult to treat.

  On the other hand, hexavalent chromium is currently widely used for surface treatments such as special steel, non-ferrous alloys, chromium plating / chromate, pigments, and tanning because of its high oxidation resistance and high melting point. This hexavalent chromium is highly toxic in chromium compounds and is designated as a hazardous substance as described above. In recent years, hexavalent chromium is contained in cement and cement solidified material, and is also eluted from solidified concrete. Therefore, since there are many concrete products and structures in our current living environment, there are concerns about the adverse effects on the environment and human body of hexavalent chromium eluted from these.

  Under such circumstances, as a method for treating hexavalent chromium, there is a so-called reduction method in which hexavalent chromium is reduced to trivalent chromium, and an alkali agent is added to precipitate and separate as chromium (III) hydroxide. It is a method (for example, refer nonpatent literature 1). In the ion exchange method, chromic acid containing hexavalent chromium is strongly adsorbed on the anion exchange resin (see, for example, Non-Patent Document 2). Conventionally, activated carbon has been used exclusively because activated carbon is easy to handle and has a high removal effect. In addition to this, biosorbents using microorganisms such as land plants, aquatic plants, seaweeds and molds are used. Research has also been conducted (for example, see Non-Patent Document 3). As coagulation precipitants, polyaluminum chloride (PAC), polyacrylamide, etc. have been used for civil engineering dredging work and turbid water solid-liquid separation in water treatment and sewage treatment plants. A large amount of shells are being disposed of. A shell is a polycrystal with small crystals of calcium carbonate, such as a ridge-pillar structure like a honeycomb, a leaf-like structure with many thin leaves stacked, a chalk structure with intersecting calcium carbonate crystals and many voids, etc. Has a variety of structures. The fine particles dispersed in water have a negative charge, and the calcium ions contained in the shell cancel the negative charge of the particles dispersed in the water and cause the particles to aggregate. Moreover, the shell is considered to have a very large surface area due to the complex crystal structure as described above.

Isao Kato, Disposal of Chromium (VI) Drainage “New Pollution Prevention Technology and Regulations 2009 Water Quality II (Pollution Prevention Technology and Regulations Editorial Board) Industrial Environment Management Association, Tokyo, 2009; 212-217 Toray Research Center Research Division, recycling of chromium (VI) wastewater. "Water Recycling / Waste Treatment Technology-Latest Trends in Drainage / Wastewater by Technical Field" (Tetsuo Ide), Gihodo Publishing Co., Ltd., Tokyo, 1976; 517-521 Murphy V, Hughes H, McLoughlin P. et al. Comparative study of chromium biosorption by red, green and brown seeded biomass. Chemosphere 2008; 70: 1128-1134.

  However, the reduction method, which is the hexavalent chromium removal method described in Non-Patent Document 1 as described above, has the effect of removing hexavalent chromium due to, for example, a regeneration reaction in which the reduced trivalent chromium partially returns to hexavalent chromium. There is a problem that is not so high. Further, in the ion exchange method described in Non-Patent Document 2, since concentrated chromic acid obtained when the resin is regenerated can be recovered, there is an advantage that it can be reused as a preservative. There is a problem that it is not suitable for large-scale waste liquid treatment because of its high cost. Further, the adsorption method described in Non-Patent Document 3 is also not suitable for large-scale waste liquid treatment because activated carbon is expensive. Also, among the biotreating agents, a method using seaweed has been shown, but there is a problem that it is not sufficient to achieve high efficiency and low cost at the research stage.

Accordingly, the present inventors have focused on the use of seaweed as an adsorbent and a large amount of shells discarded as a by-product of shellfish cultivation as a coagulant precipitant during various investigations of the above problems. research result, can be removed inexpensive and high rate to heavy metals (in particular hexavalent chromium), containing heavy metals with the seaweed component and shell component effluent treatment how heading and the present invention has been accomplished here .

Therefore, the first problem to be solved by the present invention is to provide an excellent heavy metal-containing waste liquid treatment method capable of efficiently removing heavy metals (especially hexavalent chromium) at low cost using seaweed components and shell components. There is to do. The second problem to be solved by the present invention is to provide an excellent heavy metal-containing waste liquid treatment method capable of removing heavy metals at low cost and high efficiency by simultaneously using seaweed as an adsorbent and simultaneously using shells as a coagulating precipitant. There is.

The above-described problems of the present invention are achieved by the following inventions.
(1) The waste liquid for treatment containing heavy metal includes an adsorbent composed of a seaweed calcined material selected from at least one of green algae, red algae or brown algae, and a calcined shell powder calcined at 200 ° C. to 350 ° C. A method for treating a heavy metal-containing waste liquid, comprising adding or stirring a shell aggregation coagulant sequentially or simultaneously.
(2) The heavy metal-containing waste liquid treatment method as described in (1) above, wherein the seaweed of the brown alga class is Coleoptera or Chamidae.
(3) The heavy metal-containing waste liquid treatment method according to (1) or (2) above, wherein the Chamidaceae is at least one selected from seaweed, Hirome, or Cubidae .
(4) The heavy metal-containing waste liquid treatment method according to any one of claims 1 to 3, wherein the seaweed fired product is fired at 200 ° C to 350 ° C.

The heavy metal-containing waste liquid treatment method of the present invention is obtained by adding an adsorbent comprising a seaweed calcined product that is at least one selected from the group of green algae, red algae, or brown algae to a waste liquid for treatment containing heavy metals, and then stirring. By adding and stirring the shell aggregate aggregating agent to the waste liquid obtained, the hexavalent chromium can be removed at a lower cost and with higher efficiency (FIG. 3). The heavy metal-containing waste liquid treatment method of the present invention can simultaneously mix an adsorbent composed of a seaweed calcined product and a shell aggregation precipitant containing a calcined shell, thereby efficiently removing hexavalent chromium at low cost. This is an excellent effect that can be achieved (FIG. 3). The seaweed of the seaweed baked product is at least one selected from the group of green algae, red algae, or brown algae, so that the removal rate of hexavalent chromium is good compared to the control (shell aggregation coagulant only). There is a particularly remarkable effect (FIG. 4). In the waste liquid treatment method of the present invention, seaweed of the brown algae rope is by kelp eyes Chigaiso department has more excellent effect of removing particularly hexavalent chromium (Fig. 4). In the waste liquid treatment method of the present invention, the kelp eye Chigaiso family is, seaweed, by at least one selected from the spread or beforehand, and more excellent effect of removing hexavalent chromium (Fig. 4). In the waste liquid treatment method of the present invention, the seaweed baked product by those fired at 200 ° C. to 350 ° C., in which exhibits an excellent effect that the effect of removing more hexavalent chromium is remarkable .

  The graph which shows the relationship between the kind of heavy metal and the removal rate of the heavy metal removal agent for waste liquid treatment is shown.

  Embodiments of the present invention will be described below, but this is an example and the present invention is not limited to this.

    In the description of the claims and the specification of the present application, “adding an adsorbent composed of seaweed calcined product and a shell aggregation aggregating agent sequentially or simultaneously to a waste liquid for treatment containing heavy metal” and “stirring” means “for treatment containing heavy metal Add the adsorbent composed of seaweed calcined product to the waste liquid and stir, then add the shell aggregation precipitant to the waste liquid obtained and stir "or" Adsorbent composed of seaweed calcined material and shells to the waste liquid for treatment containing heavy metals It is used to mean both methods of adding and aggregating the coagulating precipitation agent simultaneously. The present invention is a heavy metal-containing waste liquid treatment method, characterized in that an adsorbent composed of a seaweed calcined product and a shell aggregate aggregating precipitant are sequentially or simultaneously added to a treatment waste liquid containing heavy metal and stirred. Are particularly harmful heavy metals such as cadmium, lead, mercury, hexavalent chromium, arsenic, selenium, iron (III), manganese, nickel, zinc, lead, etc. The influence of is attracting attention. However, it is not limited to these, and it goes without saying that the present invention is applied to other heavy metals. In the seaweed calcined product used as the adsorbent used in the present invention, seaweeds such as green algae, red algae and brown algae are preferably used as raw materials. However, it is not limited to this.

  Examples of the green alga class used in the present invention include Aomogusa, Anaanaosa and Nagamil. Examples of the red algae include Susabirinori, Mizoogonori, Pirihiba, Saidaibara, Obatsunomata, Suginori, Fukurofunori, Hitsumatsu, Fudarak, Maxa, Fusiunagi and the like. Examples of brown algae include sea urchins, common rushes, kagomenori, mosquitoes, havanori, shigege, nebarimo, kajime, macomb, hirome, wakame, isomoku, umitranoo, ezono-nejimok, obanokogirimok, oobamoku, momoke, mom Is mentioned. The green algae, red algae and brown algae used in the present invention are specifically mentioned, but are not limited thereto. Among these, preferred are Aomogusa, Anaaaosa, Nagamil, Susapinori, Pirihiba, Obatsunomata, Fukurofunori, Fudarak, Maca, Fusutunagi, Sea Urchina, Common Rabbit, Kagomenori, Kamonomono, Habari, Naverimo, Kajime, Kajime, Mabu, Isomok, Umitorano, Ezo no Nejimok, Obanokogiri Moku, Oba Moku, Juromoku, Togemoku, Hijiki, Yatsumata Moku, Yanagimoku, Yoremok, and more preferably Anaanaosa, Fukurofunori, Umichiwa Hirome, Wakame, Isomoku, Umitorano, Hijiki, Yatsutama Tamoku, Yanagimoku, and more preferably Wakame, Hirome or Kajime.

  The seaweed fired product used in the present invention is obtained by firing seaweed as described above into seaweed charcoal and further pulverizing it into granules, powders, and the like. Preferably powder is good. The firing time of the seaweed is 150 ° C to 550 ° C, preferably 180 ° C to 450 ° C, and more preferably 200 ° C to 350 ° C. If the firing temperature is less than 150 ° C., the thickening component contained in the seaweed charcoal will adversely affect the coagulation action of the shell coagulating precipitant, which is not preferable. Further, if the firing temperature exceeds 550 ° C., not only the adsorption effect is lost, but also the production efficiency is deteriorated, which is not preferable.

  The shell aggregation precipitant used in the present invention is not particularly problematic as long as it is a shell of shellfish. The shell is a polycrystal with small crystals of calcium carbonate gathered as described above, a ridge-pillar structure like a beehive, a leaf-like structure in which many thin leaves are stacked, and a chalk with many voids intersecting with calcium carbonate crystals. It has various structures such as structures. The fine particles dispersed in water have a negative charge, and the calcium ions contained in the shell cancel the negative charge of the particles dispersed in the water and cause the particles to aggregate. Moreover, it can be said that the shell has a very large surface area due to the complex crystal structure as described above. The shells used in the present invention are preferably inexpensive and available in large quantities, and in view of the large amount of shells obtained by shellfish cultivation, such shells, especially oyster shells, are available. It is preferable because it is easy.

  The shell agglomeration precipitant used in the present invention is obtained by washing a shell, drying it, and then pulverizing it into a granule or powder to produce a fired shell powder. Furthermore, a shell agglomeration precipitant is produced by mixing polyaluminum chloride and an acrylamide polymer with the baked shell powder. The calcined shell powder preferably has a calcining temperature of 200 ° C. to 350 ° C. and a calcining time of 60 minutes to 180 minutes, and more preferably 230 ° C. to 280 ° C., but is not limited thereto.

  The waste liquid for treatment containing heavy metals used in the method for treating heavy metal-containing waste liquid of the present invention includes factory waste liquid discharged from the factory, sewage treatment waste liquid, eluate from landfill disposal site, and also generated during the manufacture of concrete products. Such as separated water, eluate eluted from solidified concrete. The adsorbent made of the seaweed calcined product as described above is added to the waste liquid for treatment containing such heavy metals and stirred. The agitation time is 2 minutes to 5 minutes, preferably even around 5 minutes, which is about 3 minutes, and hardly affects the adsorption effect. Next, when a shell aggregation coagulant as described above is added and stirred, an aggregate is formed. Thereafter, the aggregate is separated by filtration. In the waste liquid treatment method of the present invention, the adsorbent composed of the seaweed calcined product and the shell agglomerated precipitant used are added with the adsorbent and then the shell agglomerate precipitant, but the adsorbent composed of the seaweed calcined product is a heavy metal. The amount is 0.1 parts by mass or more, preferably 0.2 parts by mass or more, with respect to 100 parts by mass of the processing waste liquid. The shell aggregation precipitation is 0.2 parts by mass or more, preferably 0.5 parts by mass or more with respect to 100 parts by mass of the processing waste liquid containing heavy metals.

Further, when adding the adsorbent composed of the seaweed calcined product and the shell agglomerate precipitant containing the calcined shell used in the present invention to the waste liquid for treatment containing heavy metals, the ratio, that is, the adsorbent composed of the seaweed calcined product and the calcined sea shell. The ratio with respect to the shell aggregation precipitating agent containing is 1: 1 to 1: 5, preferably 1: 1 to 1: 3.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is for demonstrating an example and this invention is not limited to this.

[Manufacture of model waste liquid of hexavalent chromium]
As the hexavalent chromium model waste liquid used in place of the waste liquid treatment method for heavy metal-containing waste liquid of the present invention, potassium chromate aqueous solution having a concentration of 1 mg / L was prepared using potassium chromate (manufactured by Wako Pure Chemical Industries, Ltd.).
[Adsorbent]
As the adsorbent, five types of carion, synthetic zeolite, activated carbon powder, calcined onion skin powder (plant charcoal) and seaweed charcoal were tested.

[Manufacture of plant charcoal]
The baked vegetable charcoal of the onion skin was produced by firing the onion skin for 90 minutes at 250 ° C. using an oven and pulverizing it using a wonder blender (trade name WB-1 manufactured by Osaka Chemical Co., Ltd.). The average particle size was 100 μm.
[Manufacture of seaweed charcoal]
Seaweed charcoal was produced by firing various seaweeds at 250 ° C. for 90 minutes using an oven and pulverizing them using a wonder blender.

(Manufacture of shell shell coagulating precipitant)
After washing the oyster shell, it is dried, and then the dried product is pulverized with a wonder blender, and then the pulverized product that has passed through a 250 μm sieve is baked at 250 ° C. for 90 minutes using an oven to produce a baked shell powder. did. Furthermore, the shell aggregation precipitant was produced by mixing 90% by mass of this calcined shell powder, 7% by mass of polyaluminum chloride (PAC: manufactured by Daimei Chemical Co., Ltd.), and acrylamide polymer (manufactured by SNF).

The heavy metal-containing waste liquid treatment method was performed by the following method and by a batch method. 40 mL of an aqueous potassium chromate solution having a concentration of 1 mg / L was poured into 5 of 6 50 mL capacity conical tubes. 100 mg each of carion, synthetic zeolite, activated carbon powder, onion skin calcined powder (vegetable charcoal) and seaweed charcoal were added as adsorbents to each of these, and stirred for 3 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation is performed at 4000 xg for 2 minutes, and the hexavalent chromium concentration in the supernatant is determined by the diphenylcarbazide method [Masahiko Tsuji, Chromium, "Analysis Fifth Edition of Water" (Hokkaido Branch, Analytical Society of Japan) Dojin, Kyoto, 2005; 229-232], using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). Further, the remaining one conical tube was used as a control by adding only a shell aggregation coagulant. The obtained results are shown in Table 1. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = {(unprocessed value−processed value) / unprocessed value} × 100
Note that g represents gravity, and 4000 × g represents that centrifugation is performed at a gravitational acceleration 4000 times the gravity.

As is clear from Table 1, the removal rates of hexavalent chromium of carion, synthetic zeolite and plant charcoal are as low as 30%, 29% and 28%, respectively, but the removal rate of seaweed charcoal is 66% and the removal of activated carbon. The rate was close to 75%. From this result, it can be seen that seaweed charcoal is extremely excellent as an adsorbent when combined with a shell aggregation precipitant.

The heavy metal-containing waste liquid treatment method was performed by the following method and by a batch method. 40 mL of a potassium chromate aqueous solution having a concentration of 1 mg / L was poured into a 50 mL conical tube. In this, 100 mg of seaweed charcoal produced from seaweed shown in Table 2 was added as an adsorbent and stirred for 3 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation was performed at 4000 × g for 2 minutes, and the hexavalent chromium concentration contained in the supernatant was measured by a diphenylcarbazide method using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). 36 kinds of seaweed charcoal were used as raw materials for the adsorbent. Also, no adsorbent was added, and only a shell aggregation coagulant was added to serve as a control. The obtained results are shown in Table 2. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = [(unprocessed value−processed value) / unprocessed value] × 100

  As is clear from Table 2, seaweeds are found to be effective in removing hexavalent chromium. Among these, the order of the family Chamidae or the family Cubidae is prominent. It can be seen that the removal rate is 90% or more.

[Manufacture of Wakame Charcoal Powder]
Wakame seaweed, which is a seaweed belonging to the order of Coleoptera, is dried (unfired), and the wakame is fired at 100 ° C, 150 ° C, 200 ° C, 250 ° C for 90 minutes using an oven, A product baked at 350 ° C., 450 ° C., and 550 ° C. for 90 minutes using Koito Kogyo Co., Ltd., KCA-10A) was pulverized using a wonder blender to obtain Wakame charcoal powder.

[Heavy metal containing waste liquid treatment method]
The heavy metal-containing waste liquid treatment method was performed by the following batch method using wakame charcoal powder as an adsorbent. 40 mL of a potassium chromate aqueous solution having a concentration of 1 mg / L was poured into a 50 mL conical tube. 100 mg of the above Wakame charcoal powder was added as an adsorbent to this and stirred for 3 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation was performed at 4000 × g for 2 minutes, and the hexavalent chromium concentration contained in the supernatant was measured by a diphenylcarbazide method using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). Further, wakame charcoal powder was not added, and only a shell aggregation coagulant was added as a control. The obtained results are shown in Table 3. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = [(unprocessed value−processed value) / unprocessed value] × 100

  As can be seen from Table 3, the removal rate of hexavalent chromium by wakame charcoal powder has an excellent effect of 80% or more at a firing temperature of 200 ° C to 350 ° C. Moreover, viscosity is seen in the waste liquid which added the unbaked to 150 degreeC baked wakame charcoal, and the hexavalent chromium removal rate is low. This is considered that the coagulation action of the shell aggregation coagulant is inhibited. As a result of external appearance observation, green color was obtained at 150 ° C. from unfired, brown to black at 350 ° C. or higher, and a large difference in appearance was observed depending on temperature. Above 450 ° C, the hexavalent chromium removal rate becomes low.

[Heavy metal containing waste liquid treatment method]
The heavy metal-containing waste liquid treatment method was performed by the following batch method using wakame charcoal powder as an adsorbent. 40 mL of a potassium chromate aqueous solution having a concentration of 1 mg / L was poured into a 50 mL conical tube. Into this, 0 mg (control), 5 mg, 10 mg, 20 mg, 40 mg, 80 mg and 160 mg of 250 ° C. wakame charcoal powder produced in Example 3 was added as an adsorbent and stirred for 3 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation is performed at 4000 xg for 2 minutes, and the hexavalent chromium concentration in the supernatant is determined by the diphenylcarbazide method [Masahiko Tsuji, Chromium, "Analysis Fifth Edition of Water" (Hokkaido Branch, Analytical Society of Japan) Dojin, Kyoto, 2005; 229-232], using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). The results obtained are shown in Table 4. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = [(unprocessed value−processed value) / unprocessed value] × 100

  As is apparent from Table 4, the amount of wakame charcoal powder added can be a sufficient hexavalent chromium removal rate of 40 mg or more with respect to the waste liquid having a concentration of 1 mg / L. Almost 100% of hexavalent chromium can be removed. Therefore, it is not necessary from the economical viewpoint to add more than 100 mg of wakame charcoal powder.

[Heavy metal containing waste liquid treatment method]
The heavy metal-containing waste liquid treatment method was performed by the following batch method using wakame charcoal powder as an adsorbent. 40 mL of a potassium chromate aqueous solution having a concentration of 1 mg / L was poured into a 50 mL conical tube. 10 mg and 100 mg of 250 ° C. wakame charcoal powder produced in Example 3 were added as adsorbents, respectively, and the stirring time was 0.5 minutes, 1 minute, 2 minutes, 3 minutes, 5 minutes, 10 minutes, respectively. Stir for 30 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation was performed at 4000 × g for 2 minutes, and the hexavalent chromium concentration contained in the supernatant was measured by a diphenylcarbazide method using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). The obtained results are shown in Table 5. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = [(unprocessed value−processed value) / unprocessed value] × 100

  As is clear from Table 5, the addition amount of wakame charcoal powder to the waste liquid having a concentration of 1 mg / L is 10 mg and 100 mg, and the hexavalent chromium removal rate increases with the increase of the reaction time, and the reaction time is sufficient for 3 minutes. It turns out that an effect is acquired. Even if the reaction time exceeds 3 minutes, the effect is not changed. Therefore, it can be said that the treatment time is sufficient if 3 minutes have passed after the addition of the wakame charcoal powder.

[Heavy metal containing waste liquid treatment method]
The heavy metal-containing waste liquid treatment method was performed by the following batch method using wakame charcoal powder as an adsorbent. 40 mL of a potassium chromate aqueous solution having a concentration of 1 mg / L was poured into a 50 mL conical tube. The pH was adjusted to about 4, 5, 6, 7, 8, 9, 10 using 1N HCl and 1N NaOH. As an adsorbent, 10 mg of 250 ° C. wakame charcoal powder produced in Example 3 was added and stirred for 3 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation was performed at 4000 × g for 2 minutes, and the hexavalent chromium concentration contained in the supernatant was measured by a diphenylcarbazide method using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). The results obtained are shown in Table 6. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = [(unprocessed value−processed value) / unprocessed value] × 100

  As apparent from Table 6, the hexavalent chromium removal effect is high in the acidic and alkaline regions, and the hexavalent chromium removal effect is low in the weakly acidic to weakly alkaline regions. In addition, although the raise of pH was seen after a process, it is estimated that this is based on the calcium carbonate of the shell of a shell aggregation coagulant.

[Heavy metal containing waste liquid treatment method]
5 mg / L iron standard solution (Wako Pure Chemical Industries), 10 mg / L potassium permanganate solution (Wako Pure Chemical Industries), 5 mg / L nickel standard solution (Wako Pure Chemical Industries), 5 mg / L Lead aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) and an aqueous solution of 1 mg / L zinc sulfate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) were used as model waste liquids for the respective heavy metals. The heavy metal-containing waste liquid treatment method was performed by the following batch method using wakame charcoal powder as an adsorbent. 100 mg of 250 ° C. wakame charcoal powder produced in Example 3 was added to 40 mL of each heavy metal model waste solution and stirred for 3 minutes. Thereafter, 200 mg of a shell aggregation coagulant was added and stirred to form an aggregate. Centrifugation was performed at 4000 × g for 2 minutes, and the concentration of hexavalent chromium contained in the supernatant was measured using a multi-item water quality meter (Lambda 9000, manufactured by Kyoritsu Riken). The respective measurement principles used were the o-phenanthroline method for iron, the potassium periodate method for manganese, the dimethylglyoxime method for nickel, the PAR method for lead, and the zincone method for zinc. The obtained results are shown in FIG. A control that did not use an adsorbent was used as a control. The hexavalent chromium removal rate was calculated by the following formula.
Removal rate (%) = [(unprocessed value−processed value) / unprocessed value] × 100

  As is apparent from FIG. 1, the effect of removing hexavalent chromium is the same as that of the control for iron and lead, and therefore, the removal effect can be obtained only by the shell aggregation precipitant. It can be seen that nickel has a larger removal effect than the shell aggregation precipitant, and that manganese and zinc have an excellent removal effect by using wakame charcoal and shell aggregation precipitate.

[Manufacture of heavy metal removal agent for waste liquid treatment]
As an adsorbent, 100 mg of Wakame charcoal powder and 200 mg of a shell aggregation coagulant were mixed to produce a heavy metal removal agent for waste liquid treatment.

[Heavy metal containing waste liquid treatment method]
The heavy metal containing waste liquid treatment method was performed by the following method. 40 mL of a potassium chromate aqueous solution having a concentration of 1 mg / L was poured into a 50 mL conical tube. 300 mg of the above-mentioned heavy metal removal agent for waste liquid treatment was added to this, and stirred for 3 minutes. Centrifugation is performed at 4000 × g for 2 minutes to separate the formed aggregates, and the concentration of hexavalent chromium contained in the supernatant is determined by the diphenylcarbazide method [Masahiko Tsuji, Chromium, “Analysis of Water, Fifth Edition” (Analytical Chemistry Society of Hokkaido, Hokkaido Chapter) Chemistry Dojin, Kyoto, 2005; 229-232], using a multi-item water quality meter (Lambda 9000 manufactured by Kyoritsu Riken). In addition, 200 mg of only a shell aggregation coagulant was added to a conical tube into which 40 mL of an aqueous potassium chromate solution having a concentration of 1 mg / L was poured to serve as a control. The results obtained are shown in Table 7.

As is clear from Table 7, even when a heavy metal removal agent for waste liquid treatment consisting of a mixture of wakame charcoal powder and shell agglomerated precipitant is used, hexavalent chromium can be removed at a removal rate of 98.0%. did it.
Similarly, synthetic zeolite, activated carbon powder, onion skin calcined powder (vegetable charcoal) and shell aggregation coagulant were mixed as adsorbents to produce heavy metal removal agents for waste liquid treatment.

  Further, seaweed charcoal of Example 2, Wakame charcoal of Example 3, wakame charcoal of Example 4 and weight, relationship with stirring time of Example 5, relationship with pH of Example 6, Regarding the relationship with other heavy metals, even when using a heavy metal removal agent for waste liquid treatment (so-called, simultaneous addition) mixed with an adsorbent and a shell aggregation precipitant, add a shell aggregation precipitation agent after the addition of the adsorbent. Compared with the method, the same effects of the present invention were obtained.

Heavy metal-containing waste liquid treatment how the present invention, heavy metals, in particular has a significant effect on the removal of hexavalent chromium, it is possible to perform efficiently at low cost as a method for removing hexavalent chromium contained in industrial waste Therefore, it can be said that the industrial utility is extremely large.

Claims (4)

Shell flocculation precipitation comprising an adsorbent comprising a seaweed calcined material selected from at least one selected from the group of green algae, red algae or brown algae, and a calcined shell powder calcined at 200 to 350 ° C. A method for treating a heavy metal-containing waste liquid, wherein the agents are added sequentially or simultaneously and stirred. The heavy metal-containing waste liquid treatment method according to claim 1, wherein the seaweed of the brown alga is a family Cypridaceae or Cypridaceae. The method for treating a heavy metal-containing waste liquid according to claim 1 or 2, wherein the Chamidaceae is at least one selected from wakame, hirome, or kazime of the order of the Coleoptera. The heavy metal-containing waste liquid treatment method according to any one of claims 1 to 3, wherein the seaweed fired product is fired at 200 ° C to 350 ° C.

Images