KR101072492B1 - APPARATUS AND METHOD FOR TREATING OF Cr-WASTEWATER BY SEAWEEDS AND FUNGI - Google Patents

Abstract

The present invention relates to a method and apparatus for treating chromium-containing wastewater using seaweed or mold, and more particularly, chromium-containing wastewater using algae or mold to reduce and adsorb chromium by contacting chromium-containing wastewater with seaweed or mold. It relates to a treatment method and a treatment apparatus.

The present invention is capable of removing 100% of chromium from chromium-containing wastewater using dead seaweeds or molds which can be easily obtained in large quantities.

Chromium, algae, mold, reduction, adsorption

Description

Chrome wastewater treatment method and treatment apparatus using algae or mold {APPARATUS AND METHOD FOR TREATING OF Cr-WASTEWATER BY SEAWEEDS AND FUNGI}

1 is a schematic diagram of a chromium-containing wastewater treatment apparatus according to an embodiment of the present invention.

2 is a schematic diagram of a chromium-containing wastewater treatment apparatus according to another embodiment of the present invention.

The present invention relates to a wastewater treatment method and treatment apparatus capable of removing or recovering hexavalent chromium, which is harmful to humans and the environment, to trivalent chromium using dead seaweed or mold as a reducing agent.

In general, wastewater generated in the chromium plating process contains a large amount of hexavalent chromium, which is harmful to humans and the environment. In particular, hexavalent chromium is classified as a poison, so when the waste water containing chromium is released into the natural environment, the fluidity is high, and the problem of soil and water pollution is more serious than other heavy metals.

Therefore, multifaceted studies on the treatment of hexavalent chromium-containing wastewater are underway. Currently, hexavalent chromium is reduced to trivalent chromium by using a strong reducing agent such as FeSO ₄ · H ₂ O by chemical reduction and precipitation method, and then an alkali agent such as slaked lime is administered to precipitate and reduce the reduced trivalent chromium by hydroxide precipitation. The removal method is the most widely used. Such a method is suitable for treating a small amount of high concentration chromium-containing wastewater, but there is a problem in that it is not suitable for economical and efficient treatment of a large amount of low concentration chromium-containing wastewater, and the generation of chemical sludge due to the administration of a large amount of reducing agent is increased.

In this regard, Republic of Korea Application No. 2003-24881 proposes a method for treating chromium adsorbed in an ion exchange resin tower and a cation tower during the regeneration process to return chromic acid to reuse the plating process. The method can recover the hexavalent chromium in a high yield, but there is a problem that the price of the ion-exchange resin to be used is expensive, and the reuse rate is lowered due to high concentration of hexavalent chromium.

In recent years, methods for using live microorganisms for the treatment of heavy metals have been continuously studied. Republic of Korea Patent Application No. 1998-29156 is a method of culturing Inonotus cuticularis , a strain of the genus Syrup , and contacting the wastewater containing hexavalent chromium to detoxify the hexavalent chromium-containing wastewater It is mentioned. However, this method shows a chromium removal rate of 60% or less, which does not show practically high efficiency, and due to the toxicity of hexavalent chromium itself, it is insufficient to be applied to a real process, and a medium must be supplied for continuous strain growth. There is a problem.

An object of the present invention for solving the above problems is to provide a method and apparatus for removing 100% detoxification of hexavalent chromium contained in waste water.

It is another object of the present invention to provide a treatment method and a treatment apparatus capable of treating the total chromium contained in the waste water with high efficiency at low cost.

In order to achieve the above object, the present invention provides a method for treating wastewater in which seaweed or mold for reducing and adsorbing chromium is contacted with wastewater containing chromium.

In addition,

Iii) adjusting the pH to 1-3 by injecting an acid solution into the chromium-containing wastewater;

Ii) providing a method for treating chromium-containing wastewater comprising contacting the wastewater with algae or mold.

In addition,

Iii) adjusting the pH to 1-3 by injecting an acid solution into the chromium-containing wastewater;

Ii) contacting the wastewater with algae or mold,

V) adjusting the pH to 3 to 5 by injecting alkali into the treatment solution obtained in ii) above;

Iii) contacting the treatment liquid obtained in iii) with algae or mold

Provided is a method for treating chromium-containing wastewater that removes total chromium contained in wastewater.

Preferably, the chromium-containing wastewater is contacted with seaweed or mold to reduce hexavalent chromium to trivalent and adsorbed onto the surface of the algae and mold to completely remove chromium contained in the wastewater.

In addition,

a) a reservoir for storing chromium-containing waste water,

b) a pH adjusting tank in which the chromium-containing waste water is transferred from the reservoir, and an acid solution is injected from the acid reservoir, and

c) An apparatus for treating chromium-containing wastewater, in which acid-treated chromium-containing wastewater is transferred from the pH control tank, and having a reaction tank filled with dead seaweed or mold.

In addition,

a) a reservoir for storing chromium-containing waste water,

b) a first pH adjustment tank in which the chromium-containing waste water is transferred from the reservoir, and the acid solution is injected from the acid reservoir;

c) a first reaction tank in which acid-treated chromium-containing wastewater is transferred from the first pH adjusting tank and filled with dead algae or mold;

d) a second pH adjusting tank into which the treatment liquid introduced from the first reaction tank is transferred, and an alkaline solution is injected from the alkali storage tank, and

e) the alkali-treated chromium-containing wastewater is transferred from the second pH adjusting tank, and includes a second reaction tank filled with dead seaweed or mold

Provided is a wastewater treatment apparatus for removing total chromium in wastewater.

The present invention is described in more detail below.                     

Since chromium acts as a powerful oxidizing agent, it is used for cleaning method of metal, synthesis of plating, etc., and is applied in the form of chromic acid, potassium chromate, sodium chromate, sodium dichromate, chromium hydroxide and chromium sulfate. When chromium is dissolved in water, the chromium is converted into hexavalent chromium ion and exhibits strong toxicity. The wastewater generated after the above-described washing or plating process includes chromium.

Most chromium compounds have three kinds of divalent, trivalent, and hexavalent compounds, but since the divalent chromium compounds are unstable and do not exist as they are, most of the trivalent and hexavalent chromium constitute total chromium. At this time, the hexavalent chromium exhibits strong toxicity, but the trivalent chromium is harmless to the human body, so that the hexavalent chromium is reduced to trivalent using an oxidizing agent and collected and reused.

Therefore, the present invention is characterized by a method of treating chromium-containing wastewater by reducing chromium-containing wastewater by contact with seaweed or mold to reduce hexavalent chromium harmful to humans and the environment to harmless trivalent chromium, wherein the seaweed or mold Acts as a reducing agent to reduce hexavalent chromium to trivalent chromium in place of the conventional chemical reducing agent FeSO ₄ · H ₂ O.

Seaweeds and molds are organic substances composed of various carbohydrates, proteins, and lipids, and some of the organic components of the above components have properties of easily desorbing electrons to hexavalent chromium under acidic conditions. Therefore, when the seaweed or mold is contacted with hexavalent chromium, which is a strong oxidizing agent, a reduction reaction is performed in hexavalent chromium and an oxidation reaction in algae or mold by strong oxidation / reduction reactions between the reactants.                     

The chromium-containing wastewater to be treated in the present invention is a by-product after washing or plating, and contains a large amount of hexavalent chromium ions in an aqueous solution. When the wastewater is brought into contact with seaweeds or molds, oxidation of various organic components present in seaweeds or molds Hexavalent chromium is rapidly reduced to trivalent chromium by the reduction / reduction reaction and is adsorbed by electrostatic attraction to carboxyl groups or hydroxyl groups on the surface of algae or mold. At this time, the adsorbed trivalent chromium may be re-used after being desorbed from the surface of algae or mold through a separate treatment, and then reused for cleaning or plating.

These algae or molds can also be used to kill, not only low price, but also very high reduction rate of hexavalent chromium to trivalent chromium, compared to FeSO ₄ · 7H ₂ O (Iron Sulphate), which is conventionally used as a chromium reducing agent. 3 times higher per unit mass, thereby allowing the replacement of chemical reducing agents such as FeSO ₄ .7H ₂ O. Specifically, in order to completely oxidize one mole of hexavalent chromium to trivalent chromium, theoretically 834 g of FeSO ₄ H ₂ O is required. In contrast, 223 g is required when using the most preferred gompi as mentioned in the preferred embodiment 1 of the present invention, which shows a reduction rate of 100% even in a small amount compared to the chemical reducing agent.

Seaweeds according to the present invention can be easily obtained in a large amount in nature, any one of green algae (brown algae), brown algae (red algae) and red algae (red algae) is not particularly limited in the present invention. Representatives of the green algae are hearing, thorny greens and hot greens, and brown algae are available for seaweed, gompi, kelp, maban and 톳, and red algae are seaweeds that can be easily purchased from laver and sea urchin.

Fungi are by-products of the fermented food or pharmaceutical manufacturing process, and include Aspergillus sp. , Rhizopus sp. , Saccharomyces sp. And Penicillium sp. Fungi (including yeast) such as Penicillium sp .

At this time, the reaction rate of the reduction reaction of hexavalent chromium to trivalent chromium and the oxidation reaction of algae or mold is greatly related to the pH of the treated solution or wastewater. Trivalent chromium, which is present as a cation, is adsorbed through cation exchange on carboxyl groups present on the surface of seaweeds or molds, so that the higher the pH (i.e., the less the hydrogen ions), the higher the removal rate and performance. On the other hand, in the case of hexavalent chromium, which is present as an anion, hydrogen ions are consumed in the reduction reaction to trivalent chromium, so that the lower the pH (that is, the more hydrogen ions), the removal rate and the performance increase.

Preferably, in order to increase the oxidation / reduction rate, the algae or the fungus is washed with an acid solution to remove alkali ions such as Na or K present on the surface, and then used after a pretreatment step of drying. This acid washing is accomplished by preparing a solution having 0.01 M to 10 M with a strong acid such as nitric acid, sulfuric acid or hydrochloric acid and then stirring at room temperature for at least 1 hour, preferably 12 to 24 hours.

In addition, it is preferable to maintain the pH of the wastewater to 1 to 3 in order to increase the oxidation / reduction reaction rate. If the pH of the wastewater is adjusted to 1 or less, it is uneconomical because it consumes a large amount of acid. If the pH of the wastewater is neutral or alkaline, the oxidation / reduction reaction rate is lowered. This problem arises.

According to preferred embodiments of the present invention, the removal rate of hexavalent chromium was measured by contacting chromium-containing wastewater with seaweeds or molds. The removal rate is shown.

In addition to this treatment, algae or mold were applied in several stages to completely remove total chromium, including hexavalent chromium, contained in the wastewater.

Specifically, the total chromium contained in the wastewater

Iii) adjusting the pH to 1-3 by injecting acid into the chromium-containing wastewater;

Ii) contacting the wastewater with seaweed or mold to reduce all hexavalent chromium to trivalent chromium;

V) adjusting the pH to 3 to 5 by injecting alkali into the treatment solution obtained in ii) above;

Iii) Trivalent chromium is removed by contacting the treatment solution obtained in iii) with seaweed or mold.

In this case, steps iii) and ii) are steps for completely reducing hexavalent chromium to trivalent chromium, in which part of the trivalent chromium is removed through adsorption. In order to completely remove the total chromium (trivalent chromium) remaining in the treatment liquid obtained in step ii), alkali is used in the step iii) to improve the removal rate and performance of trivalent chromium. If the pH of the treatment solution is less than 3, a problem occurs that the adsorption rate and performance of trivalent chromium is poor, and when the pH of the treatment solution is greater than 5, a problem of forming a chromium hydroxide deposit is caused.

The alkali may be a strong or weak base commonly used in the art, typically NaOH, NH ₄ OH, KOH, Ca (OH) ₂ , Ba (OH) ₂ , Al (OH) ₃ and Na ₂ CO ₃ At least one selected from the group consisting of is possible.

1 shows a chromium-containing wastewater treatment apparatus according to an embodiment of the present invention.

Referring to Figure 1, the treatment apparatus according to the present invention

a) a reservoir (10) for storing chromium-containing wastewater,

b) a pH adjusting tank 14 to which chromium-containing wastewater is transferred from the reservoir 10, and an acid solution is injected from the acid reservoir 12, and

c) The acid-treated chromium-containing wastewater is transferred from the pH adjusting tank 14, and includes a reaction tank 16 filled with dead seaweed or mold.

2 shows a chromium-containing wastewater treatment apparatus according to another embodiment of the present invention.

Referring to Figure 2, the treatment apparatus for removing the total chromium in the wastewater

a) reservoir 20 for storing chromium-containing wastewater,

b) a first pH adjusting tank 24 into which chromium-containing wastewater is transferred from the reservoir 20 and an acid solution is injected from the acid reservoir 22,

c) a first reaction tank 26 in which acid-treated chromium-containing wastewater is transferred from the first pH adjusting tank 24 and filled with dead seaweed or mold;

d) a second pH adjusting tank 28 into which the treatment liquid introduced from the first reaction tank 26 is transferred, and an alkaline solution is injected from the alkali storage tank 30, and

e) Alkali-treated chromium-containing wastewater is transferred from the second pH adjusting tank 28, and a second reaction tank 32 filled with dead seaweed or mold is provided.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are only examples of the present invention, and the present invention is not limited to these examples.

Eight seaweeds, as shown in Table 1 below, were acid washed for 24 hours with 1 M sulfuric acid solution for 1 day and then dried at 80 ° C. for 24 hours. Then 1 g of dried seaweed was added to 200 ml of 100 mg / l hexavalent chromium solution and stirred at 200 times per minute in a stirrer. The pH of the solution was kept constant at 2 with sulfuric acid. The obtained results are shown in Table 1, and Table 1 shows the hexavalent chromium removal rate (%) according to the contact time of eight kinds of seaweeds and hexavalent chromium.

Contact time (hr) 3 10.5 24 42 84 204 373 589 Green algae Spiny blue 35.3% 51.1% 63.6% 74.1% 87.4% 100% 100% 100% ear 16.1% 23.8% 32.1% 41.1% 53.4% 77.3% 92.1% 100% Brown algae Gompi 41.6% 77.7% 95.6% 100% 100% 100% 100% 100% Mother and child 33.5% 53.9% 74.0 87.6% 100% 100% 100% 100% Seaweed 33.0% 52.2% 72.9% 87.5% 100% 100% 100% 100% Kelp 17.6% 30.0% 46.1% 58.3% 75.9% 97.2% 100% 100% Red algae Kim 32.7% 46.6% 63.0% 74.0% 86.8% 100% 100% 100% Woodfish 14.0% 22.0% 35.1% 43.5% 59.3% 85.5% 96.1% 100%

According to Table 1, it can be seen that all eight types of seaweeds remove 100 mg / l of hexavalent chromium with trivalent chromium 100%. In particular, in the case of gompi of brown algae, it can be seen that it can be used as the most effective reducing agent, showing a 100% removal rate after 42 hours.

<Example 2>

Four fungi as shown in Table 2 were incubated for 7 days, then sterilized for 40 minutes at 121 ℃, and dried for 24 hours at 80 ℃. 1 g of the obtained mold were added to 200 ml of a 50 mg / l hexavalent chromium solution, respectively, and stirred 200 times per minute in a stirrer. The pH of the solution was kept constant at 2 with sulfuric acid. Table 2 shows the hexavalent chromium removal rate (%) according to the contact time of the four molds and hexavalent chromium.

Contact time (hour) One 5 21 48 122 218 254 Reoper Duck
( Rhizopus oryzae ) 21.4% 53.2% 91.6% 100% 100% 100% 100% Penicillium chrysogenum 21.8% 30.4% 56.4% 73.2% 92.2% 100% 100% Aspergillus Niger
( Aspergillus niger) 11.6% 26.0% 48.0% 66.6% 88.8% 100% 100% Saccharomyces TV
( Saccharomyces cerevisia ) 26.0% 39.0% 57.4% 69.2% 85.4% 98.0% 100%

According to Table 2, all of the four dead mold was able to confirm that the removal of 100% of 50 mg / l of hexavalent chromium, in particular, the fastest removal rate of hexavalent chromium in the paper species.

<Example 3>

In Example 1, the hexavalent chromium removal rate of gomphy, which was pretreated with an acid and an alkaline solution, was examined in order to find an appropriate pretreatment solution using the gompi having the best removal rate.

As shown in Table 3 below, 1M acid (H ₂ SO ₄ , HCl, HNO ₃ ) solution and 1M alkaline (NaOH, NH ₄ OH) solution were placed in Gompi, washed for 1 day, and then washed at 80 ° C. for 24 hours. Dried. 1 g of dried Gompi was then added to 200 ml of 50 mg / l hexavalent chromium solution and stirred at 200 times per minute in a stirrer. The pH of the solution was kept constant at 2 with sulfuric acid. Table 3 shows the hexavalent chromium removal rate (%) according to the contact time of gompi and hexavalent chromium.

Cleaning solution Contact time (hour) 1.5 3 7 9 12 24 33 45 Distilled water 46.8% 66.4% 90.0% 96.4% 100% 100% 100% 100% mountain HNO ₃ 62.4% 81.0% 98.4% 100% 100% 100% 100% 100% H ₂ SO ₄ 58.8% 78.6% 98.0% 100% 100% 100% 100% 100% HCl 55.4% 74.6% 96.6% 100% 100% 100% 100% 100% alkali NH ₄ OH 36.0% 53.6% 70.0% 76.6% 84.0% 96.4% 100% 100% NaOH 25.4% 49.8% 58.4% 65.2% 73.4% 89.2% 95.6% 100%

As shown in Table 3, all of the gomphy pretreated (washed) with distilled water, acid and alkali showed a 100% removal rate of hexavalent chromium when it was in contact with hexavalent chromium for a long time, but when pretreated (washed) with acid 6 The removal rate of chromium was the best. These results indicate that the hexavalent chromium removal rate and speed of chromium-containing wastewater are excellent when pickling algae or mold used as a reducing agent.

<Example 4>

In Example 1 was performed as follows to determine the appropriate pH range using the gompi the best removal rate.                     

1 g of dried Gompi was added to 200 ml of 100 mg / l hexavalent chromium solution and stirred in a stirrer 200 times per minute. The pH of the solution was kept constant at 1, 2, 3, 4 using sulfuric acid, respectively. Table 4 shows the hexavalent chromium removal rate (%) according to the contact time of gompi and hexavalent chromium.

Contact time (hour) 0.2 One 3 12 48 72 pH 1 25.0% 65.6% 98.0% 100% 100% 100% pH 2 18.7% 40.0% 71.6% 99.4% 100% 100% pH 3 9.4% 22.5% 38.1% 71.6% 100% 100% pH 4 6.9% 13.4% 25.0% 44.1% 91.4% 100%

As shown in Table 4, it can be seen that as the pH of the treatment liquid is lowered, the removal rate of hexavalent chromium increases. These results indicate that the lower the pH, the better the hexavalent chromium removal rate and speed of the chromium-containing wastewater when using algae or mold used as a reducing agent.

Example 5

A treatment apparatus as shown in FIG. 2 was manufactured in a laboratory size to adsorb total chromium while simultaneously detoxifying hexavalent chromium to trivalent chromium.

The chromium-containing wastewater is injected with wastewater containing 37.5 mg / l of hexavalent chromium and 42.8 mg / l of total chromium into the reservoir, and then the chromium-containing wastewater is introduced into the first pH control tank to recover the acid from the acid reservoir. PH was adjusted to 2. Subsequently, the acid-treated treatment solution was injected into the first reaction tank filled with gompi, and then introduced into the second pH control tank to adjust the pH to 4 using alkali introduced from the alkaline bath. Next, the alkali-treated treatment liquid in the second pH adjustment tank was introduced into the second reaction tank filled with gompi, and then transferred to the collection tank.

At this time, the concentration of hexavalent chromium and total chromium according to the operating time in the first reactor and the second reactor was measured and shown in Table 5 below.

Operating hours 3 8 23 47 72 108 171 220 First reaction tank Hexavalent chromium 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l Total chrome 0 mg / l 1.5 mg / l 11.8 mg / l 12.0 mg / l 14.4 mg / l 20.1 mg / l 24.4 mg / l 27.5 mg / l Second reaction tank Hexavalent chromium 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l 0 mg / l Total chrome 0 mg / l 0 mg / l 0 mg / l 0.3 mg / l 0.8 mg / l 2.0 mg / l 3.3 mg / l 10.0 mg / l

According to Table 5, the concentration of hexavalent chromium in the treatment liquid passed through the first reactor was removed at 100% or more at 0 mg / l, and the concentration of total chromium in the treatment liquid passed through the second reactor was also about 72 hours. Almost removed below 1 mg / l.

As described above, the present invention uses toxic hexavalent chromium trivalent chromium using dead mold (including yeast), which is a by-product of a large amount of dead seaweed and fermented foods and pharmaceuticals, which are easily obtained in nature. In addition to 100% detoxification, it has the advantage of completely removing the total chromium by treating with the algae or mold in two steps. In particular, gopi, brown algae, can replace the existing chemical reducing agent because the hexavalent chromium reduction performance per unit mass is three times higher than that of commercially available chromium reducing agent FeSO ₄ · H ₂ O.

Claims (11)

delete delete Iii) adjusting the pH to 1-3 by injecting an acid solution into the chromium-containing wastewater; Ii) contacting the wastewater with algae or mold, Iii) adjusting the pH to 3-5 by injecting an alkaline solution into the treatment solution obtained in ii) above; Iii) contacting the treatment liquid obtained in iii) with algae or mold A method for treating chromium-containing wastewater which removes total chromium contained in wastewater. The method of claim 3, wherein the alkaline solution comprises at least one selected from the group consisting of NaOH, NH ₄ OH, KOH, Ca (OH) ₂ , Ba (OH) ₂ , Al (OH) ₃ and Na ₂ CO ₃ . Waste water treatment method characterized in that. The method of claim 3, wherein the acid solution comprises at least one selected from the group consisting of nitric acid, sulfuric acid and hydrochloric acid. The method of claim 3, wherein the algae is at least one selected from the group consisting of green algae, brown algae, and red algae. According to claim 6, wherein the green algae is one species selected from the group consisting of auditory, spiny blue, hot green and blue sea, the brown algae is one selected from the group consisting of seaweed, gompi, kelp, hatban, rhubarb and 톳, The red alga is a method for treating wastewater, characterized in that one species selected from the group consisting of laver, woodworm, and carrageenan. The method of claim 3, wherein the fungus is composed of Aspergillus sp. , Rhizopus sp. , Saccharomyces sp. And Penicillium sp. Waste water treatment method characterized in that at least one selected from the group. The method of claim 3, wherein the algae or mold is used after pickling and drying with an acid solution of 0.01M to 10M. delete a) a reservoir for storing chromium-containing waste water, b) a first pH adjustment tank in which the chromium-containing waste water is transferred from the reservoir, and the acid solution is injected from the acid reservoir; c) a first reaction tank in which acid-treated chromium-containing wastewater is transferred from the first pH adjusting tank and filled with dead algae or mold; d) a second pH adjusting tank into which the treatment liquid introduced from the first reaction tank is transferred, and an alkaline solution is injected from the alkali storage tank, and e) a second reaction tank filled with dead algae or mold is transferred to the treatment liquid alkali-treated in the second pH control tank; Wastewater treatment system for removing total chromium in wastewater.

Images