KR100332486B1 - A Continuous countercurrent treatment method for the removal of heavy metal ions from waste by multistage air bubble column - Google Patents

Abstract

The present invention relates to a method and apparatus for treating heavy metal-containing wastewater by biological adsorption in a multi-stage air bubble contacting tank. The present invention provides continuous contact between wastewater and adsorbent during treatment by biological adsorption of heavy metals in wastewater. In addition, the adsorbents newly supplied according to the wastewater treatment process come into contact with the wastewater having a low concentration of heavy metals, and the adsorbents that have undergone the constant adsorption process have a countercurrent contact with the new wastewater having a high concentration. By allowing heavy metal wastewater and biological adsorbents to be contacted in a continuous countercurrent direction, the current batch of heavy metal treatment systems can be converted to continuous heavy metal treatment systems and more economical environmental treatment by reducing the use of heavy metal adsorbents. One air to provide the system It is an object of the present invention to provide a method and apparatus for treating a continuous heavy metal-containing wastewater by wool countercurrent contact. To achieve the above object, the air and wastewater are passed through each stage by fractionation by a valve having several small holes. However, the adsorbent is composed of multiple stages that stay at the stage.In each stage, the heavy metal is processed by contact with the adsorbent of living organism or biological origin by the flow of air bubbles supplied from the bottom through the wastewater passing from the bottom to the top between the valve holes The present invention provides a method and apparatus for treating continuous heavy metal-containing wastewater by a multi-stage air droplet contacting tank, characterized in that the valve is opened to exchange the adsorbent from the upper end to the lower end.

Description

A countercurrent treatment method for the removal of heavy metal ions from waste by multistage air bubble column}

The present invention relates to a method and apparatus for treating heavy metal-containing wastewater using a biological adsorption method in a multi-stage air bubble contact tank, and more particularly, to a multistage contact treatment that is effective in adsorbing heavy metal in wastewater using a biological adsorbent. The present invention relates to a method for treating continuous heavy metal-containing wastewater by a multi-stage air bubble contact method of performing a process continuously in a single air bubble contact tank.

In general, in the case of treating heavy metal-containing wastewater such as lead, nickel, copper, chromium, and the like, such as cadmium, conventionally, it is mainly removed in the form of insoluble precipitates of sulfides or hydroxides or treated by an ion exchange method.

Among the above methods, the treatment method by insoluble precipitate formation has to go through complicated treatment process such as chemical treatment of waste water, control of pH, removal of generated precipitate, and even if the insoluble sulfide or hydroxide is removed by precipitation, In addition to being dissolved, the generated sludge has the problem of causing another pollution as secondary pollutants, so the existing methods described above have disadvantages that are expensive or inefficient.

Recently, as one of the methods for overcoming the above-mentioned disadvantages, there is a growing interest in the field of biological heavy metal processing using living organisms or bio-derived materials. Since there is an ability to retain metal ions therein, studies are being actively conducted to treat heavy metals in wastewater by biological adsorption using the same.

However, in order to apply such a biological adsorption method to the actual waste water, there are a number of problems in reality, one of the most serious problems is that it is difficult to treat the waste water continuously because the adsorption process itself is a batch.

In other words, due to the adsorption property, the pore or active point saturates over time and adsorption does not proceed anymore, so after a certain period of time, the treatment must be stopped and the adsorbents must be replaced. However, the wastewater to be treated is treated continuously. Because of this, there is a difficulty in this process.

In addition, the heavy metal adsorbent as described above has a problem that the adsorption proceeds only until the equilibrium with the heavy metal in the surrounding fluid during the treatment process so that the adsorption capacity in the adsorbent can not be used anymore.

The present invention is to solve the conventional problems as described above, it is possible to continuously contact the waste water and the adsorbent during the treatment by the biological adsorption method of heavy metal material in the waste water, and the adsorbent newly supplied according to the waste water treatment process The adsorbent, which is in contact with the wastewater with low heavy metal concentration and performs a constant adsorption process, is allowed to make countercurrent contact with the new wastewater with high concentration, so that the heavy metal wastewater and the biological adsorbent are contacted in the continuous countercurrent direction. Continuous heavy metals by multi-stage air bubble countercurrent contact, which enables the conversion of batch heavy metal treatment systems currently implemented to continuous heavy metal treatment systems, thereby providing a more economical environmental treatment system by reducing the use of heavy metal adsorbents. Treatment method of wastewater The purpose is to provide the device.

1 is a schematic diagram showing the structure of a heavy metal processing apparatus of the present invention

2 is an installation sectional view illustrating a state in which the valve is installed.

Figure 3 is a comparison graph of the cadmium adsorption rate in the open and closed state of the valve of each stage of the heavy metal processing apparatus of the present invention

Figure 4 is a graph of the adsorption rate of cadmium ions by kelp in the present invention heavy metal processing apparatus

5 is a graph showing the adsorption rate of cadmium ions by pure sodium alginate beads in the heavy metal treatment apparatus of the present invention

Figure 6 is a graph of the adsorption rate of cadmium ion by the exchange of pure sodium alginate beads in the heavy metal treatment apparatus of the present invention

<Description of the symbols for the main parts of the drawings>

11: original wastewater inlet 21: rotary operation valve

22: Plate 23: Plate Hole

24: screw 25: support pin

26: 'O' ring 27: gasket

28: bolt 29: nut

31,32,33,34,35: Contact treatment tank

51, 52, 53, 54: sample outlet 41: air inlet

61: adsorbent outlet 71: treated wastewater outlet

The present invention for achieving the above object is a wastewater inlet and outlet; Each stage is divided by a plate with many holes having a smaller size than the adsorbent, and is composed of multiple stages. A support pin and a rotary control valve are installed at one side of the plate to enable opening and closing of the plate. A contact treatment tank in contact with; An air inlet configured at one side of the lowermost contact treatment tank; Provided is a continuous heavy metal-containing wastewater treatment apparatus by a multi-stage air droplet contact method characterized in that it comprises a sample outlet formed on one side of the treatment tank of each stage.

In addition, each stage is divided by a valve with several small holes, and air and waste water are passed through, but the adsorbent is composed of multiple stages to stay at the stage.In each stage, air is supplied from the wastewater passing from the bottom to the top between the valve holes. Process of treatment of continuous heavy metal-containing wastewater by multi-stage air bubble contact tank, characterized in that the droplets are brought into contact with the adsorbents of living organisms or biological origins to treat the heavy metals and periodically open the valve to exchange the adsorbents from top to bottom. And its apparatus.

The opening and closing valves used in the contact treatment tank of each stage in the present invention is not limited to the type, but a butterfly valve (butterfly valve) is preferable. The butterfly valve rotates the disc to open the pipeline to an appropriate degree, and the adsorbent used to induce the flow of wastewater naturally upstream without the adsorbent flowing out of the treatment tank at each stage through the perforated hole. According to the present invention, a sieve plate having an appropriate size and number of holes can be easily replaced. The contact material is introduced in the continuous heavy metal-containing wastewater treatment apparatus by the air droplet contact treatment tank of the present invention having the configuration described above. The appropriate amount is injected from the uppermost end, and is first placed in the uppermost contact treatment tank 35. The contact material introduced into the uppermost contact treatment tank 35 is rotated while the body plate 22 is rotated by the operation of the rotation control valve 21. The contact material which is transferred to the contact treatment tank 34 at the lower end and is put into the contact treatment tank 35 at the uppermost level by repeating such an operation. Is transferred to the lowermost contact treatment tank 31, and the contact material is filled in the contact treatment tanks 32, 33 and 34 of each stage by the repeated operation. An air bubble contact treatment tank filled with a contact material supplies wastewater containing heavy metals from the lower side and simultaneously supplies air through the air inlet 41, causing air bubbles to float, thereby causing contact treatment tanks 31, 32, 33, and 34 to be filled. As the wastewater and contact material filled in the 35 are mixed, the contact becomes easy, and the wastewater and the air are moved to the upper contact treatment tank by the body plate 22, so that heavy metals are removed by the contact material. The contact material of the contact treatment tank 31 installed in the containment contains the most heavy metal, and as it goes up, it is contaminated with less heavy metal, so the performance of the contact material is filled in the lower contact treatment tank. Since the performance is changed in a reduced state as compared with the contact material filled in the upper contact treatment tank, each contact treatment tank 31, 32, 32 through the sample outlets 51, 52, 53, and 54 from time to time. 33) (34) (35) When wastewater is collected inside and the concentration of heavy metals is measured and the contact material is poor in performance, first, the wastewater inlet 11 and the air inlet 41 are closed to raise air and wastewater. Remove the adsorbent accumulated on the gate valve (V) by opening the adsorbent outlet (61) installed at the bottom end. When the contact material accumulated on the gate valve (V) is removed, the contact treatment tank located at the upper part thereof is removed. The rotary operation valve 21 of 31 is rotated to open the partition wall by the body plate 22 therein so that the contact material moves by gravity to the gate valve V of the adsorbent outlet 61 by gravity, and then the lowest contact. When the rotary operation valve 21 of the processing tank 31 is returned to its original position, The partition wall is formed by the body plate 22, and then the rotary operation valve 21 of the contact treatment tank 32 at the upper end thereof is rotated to open the partition wall by the body plate 22 therein so that the contact material is lowered by gravity. And the rotary operation valve 21 of the contact treatment tank 32 is returned to its original position, and the partition plate is formed by the body plate 22. Repeating the opening and closing of the body plate 22 by the operation of the rotary control valve 21 while repeatedly proceeding from the bottom end to the top end, the contact treatment tanks 32, 33, 34 and 35 of each stage are repeated. The contact material filled in the interior of the contact is moved to the contact treatment tanks 31, 32, 33, 34 at the lower end thereof, and the uppermost contact treatment tank 35 is installed on the upper portion thereof (shown in the drawing). If not, open the lid with the water hole and add an appropriate amount.

Adsorbents made of living organisms or bio-derived substances filled in the contact treatment tanks of the stages are not limited to the type thereof, but oyster mushroom waste medium, kelp or sodium alginate beads, etc., exhibiting excellent adsorption capacity to major heavy metals such as cadmium and copper. Preference is given to using alone or mixtures.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

<Example 1>

This embodiment is an example in which cadmium ions are removed by using the waste mushroom culture medium fixed on the sodium alginate beads in the treatment apparatus for continuous heavy metal-containing wastewater by the air bubble contact method of the present invention.

In this embodiment, the contact tank used as an example of the treatment device for wastewater containing heavy metals is divided into multiple stages by the body plate 22 which can be opened and closed by rotating operation of the rotary operation valve 21 as shown in FIG. And at each end, the contact treatment tank (31) (32) (33) (34) (35) in contact with the waste water while the adsorbent is flowed by the air; A raw waste water inlet 11 and an air inlet 41 formed at one side of the lowermost contact treatment tank 31; It consists of the sample outlet 51, 52, 53, 54 comprised in the one side of the contact processing tank 31, 32, 33, 34, 35 of each said stage.

Reference numeral V denotes a gate valve for sorbent discharge.

FIG. 2 is an installation cross-sectional view illustrating a state in which openable valves used for securing flow paths of a sieving plate partitioning contact treatment tanks at each stage are installed, and a sieve plate 22 has a diameter smaller than that of the sorbent depending on the sorbent used. It has a size and has a hole (23) is adjusted so that the flow of waste water flows up naturally, it is coupled by the rotary operation valve 21 on one side and the support pin (25) on the opposite side to process each stage It is supposed to partition the jaw.

On the other hand, it is sealed by the 'O' ring 26 so that the waste water does not leak between the gap where the rotary operation valve 21 and the support pin 25 are coupled, and by the screw 24 so as not to be separated from the wall. It is fixed.

In addition, a gasket 27 is provided between each contact treatment end and the partition end and is fixed by the bolt 28 and the nut 29 so that waste water does not leak between the contact treatment stage and the partition end by the body plate.

First, cadmium compound (CdSO4 · nH2O) was used as a heavy metal material used in the heavy metal solution, and as the test material, the waste mushroom waste medium immobilized on alginic acid was used. After drying for 12 hours in a dryer of crushed finely by using a mortar and then mixed with 2g finely ground waste mushrooms in 1% (W / V) sodium alginate, mixed with calcium chloride (CaCl2) 1.323g / distilled water Drop into 500 ml (dH 2 O) to form beads.

Subsequently, 720 ml of a 3 ppm cadmium solution was filled into the contact tank as a test heavy metal solution made of the cadmium compound, and 100 g of the adsorbent beads made above were contacted to each stage 31, 32, 33 and 34. (35) divided by 20 g, but the rotary operation valve 21 of each stage is closed so that the adsorbent beads do not fall in the state where the heavy metal solution can be flowed upward, and then, 3 ppm cadmium solution at a rate of 12 ml / min. It flows in and injects air using the air inlet 41, and it drives. Whatman filter paper No. After filtering to 42 (Φ110 mm), the cadmium content was measured using AA-6701F (SHIMADZU) atomic absorption spectrophotometer, and the results are shown in FIG. 3.

Comparative Example 1

The same procedure as in Example 1 was performed, but after the rotary operation valves 21 at each stage were opened as in the general contacting tank, the results are shown in FIG. 3.

As can be seen from the results of FIG. 3, after 390 minutes, the removal rate of 95% was shown in Comparative Example 1, but in Example 1 of the present invention, the removal rate of 99% was shown in 240 minutes, thereby improving the cadmium removal efficiency. It can be seen that the remarkable improvement. This is because the bead in the contact tank does not circulate freely up and down freely in the open air bubble contact tank with the valve open, the efficiency is lowered more than in the contact tank of the present invention in which the valve is closed. It is proving that the heavy metal treatment tank of the invention is much more efficient than the general air bubble contact tank.

<Example 2>

This embodiment removes cadmium ions using kelp known as a cadmium-selective biological adsorbent in the apparatus for treating continuous heavy metal-containing wastewater by the air bubble contact method of the present invention.

The same procedure as in Example 1, except that 25ppm cadmium solution was used as the test heavy metal solution, finely chopped kelp by hand and then divided into 5 groups of 3g each soaked in distilled water and then using 1N-hydrochloric acid After calibrating to pH 5.0 and leaving it for 15 hours, it was washed twice with distilled water and placed in the contact treatment tanks 31, 32, 33, 34 and 35 of each stage.

Then, 25 ppm cadmium solution was introduced at a flow rate of 24 ml / min. Subsequently, the effluent from the treated wastewater outlet 71 was received at regular time intervals. After filtering to 42 (Φ110 mm), the cadmium content was measured using AA-6701F (SHIMADZU) atomic absorption spectrophotometer, and the results are shown in FIG. 3.

As can be seen from the results of FIG. 4, after 85 minutes of removal rate was shown in 20 minutes, the removal rate was more than 90% after 90 minutes, and the fracture limit point phenomenon did not occur until 390 minutes after the analysis. Demonstrated the ability to

Recently, many biological adsorbents of seaweed origin have been developed. From the above results, it was found that biological adsorbents of seaweed origin such as seaweed can be efficiently treated through the air bubble contact tank of the present invention.

<Example 3>

This embodiment removes cadmium ions using a sodium alginate biological adsorbent in a treatment apparatus for continuous heavy metal-containing wastewater by the air bubble contact method of the present invention.

In the same manner as in Example 1, in order to determine the adsorption capacity of the sodium alginate beads to fix the adsorbent, the flow rate was 24ml / min, the amount of beads was 25g divided by 5g each stage and tested.

3 ppm cadmium solution was used as the heavy metal solution, and the test material was 1% (W / V) of sodium alginate in 1.323 g of calcium chloride (CaCl 2) / 500 ml of distilled water (dH 2 O) to make sodium alginate beads.

Whatman filter paper No. After filtering to 42 (Φ110 mm), the cadmium content was measured using AA-6701F (SHIMADZU) atomic absorption spectrophotometer, and the results are shown in FIG. 5.

As can be seen from the results of FIG. 5, it showed a good cadmium removal rate of 76% in 90 minutes. As a result, the adsorption capacity is lower than that of beads immobilized with Pleurotus erythrocytes in pure sodium alginate, but sodium alginate beads, which are known as representative biological adsorbents, can be applied in the J-L air bubble contact tank.

In addition, after 90 minutes, the adsorption capacity of the beads decreases and the cadmium removal rate gradually decreases, indicating a breakdown threshold phenomenon. Therefore, after 100 minutes, the adsorbent needs to be replaced.

That is, 25 g of sodium alginate beads should be exchanged every 100 minutes to prevent breakage limit. In order to prevent such breakdown point phenomenon, the adsorbents need to be replaced, but the normal air bubble contact tank has to be replaced at a time before the breakdown point phenomenon occurs, but the heavy metal treatment tank of the present invention sequentially exchanges these adsorbents little by little to prevent the breakdown point phenomenon. Therefore, there is an advantage that can reduce the amount of adsorbent consumed per unit time.

<Example 4>

This embodiment is to confirm the above-mentioned advantages, it is carried out in the same manner as in Example 3, using sodium alginate beads as the adsorbent, 5g sodium alginate beads are exchanged at each stage every 60 minutes, cadmium in the contact bath Adsorption was performed and the results are shown in FIG. 4.

In order to change the beads, first stop the air bubble injection, open the bottom valve (V) to discharge the adsorbent through the adsorbent outlet (61) and open the rotary control valve (21) just above it, The body plate 22 is rotated 90 degrees to be positioned vertically to open the conduit to move the upper adsorbent to the lower end.

In this way, the adsorbents are continuously replaced in the order of (31) (32) (33) (34) and (35) stages, and a fresh adsorbent is supplied to the top stage. This exchange causes the adsorbent to periodically move from top to bottom.

As can be seen from the results of FIG. 4, as shown in FIG. 5, 25 g is consumed as in FIG. 5, but there is no fracture limit phenomenon. Considering the fact that 25g should be replaced every 100 minutes in order to prevent the breakdown point in FIG. 4, it was found that the heavy metal treatment apparatus of the present invention can prevent the breakdown point with only 1/3 of the adsorbent.

Therefore, the heavy metal treatment apparatus of the present invention was found to be capable of reducing the amount of adsorbent used as well as continuous countercurrent adsorption.

As described above, the present invention is capable of continuously contacting the adsorbent and the heavy metal-containing waste water so that the treatment capacity is excellent and the amount of the adsorbent used due to countercurrent contact can be effectively used for wastewater treatment. In addition, the present invention can obtain an excellent heavy metal treatment efficiency even when applying a material that can be easily obtained from the surroundings, such as waste resources or algae as an adsorbent, it can exhibit a remarkable improvement in terms of treatment cost.

Claims (3)

Air and waste water are passed through, but the adsorbent is divided into multiple stages by an openable valve with multiple holes to stay at the stage.In each stage, air bubbles are supplied from the bottom through which waste water passes from the bottom to the top. A method for treating continuous heavy metal-containing wastewater by the air droplet contact method, wherein the adsorbent is exchanged from the upper end to the lower end by contact with the adsorbent of the living organism or biological source by the flow of. The method of claim 1, wherein the adsorbents of living organisms or bio-derived materials filled in the contact treatment tank of each stage is a continuous heavy metal content by air droplet contact method, characterized in that the solenoid mushroom medium, kelp or sodium alginate beads alone or a mixture thereof. Waste water treatment method. A raw waste water inlet 11; Each stage is divided by a plurality of perforated plate 22 having a smaller size than the adsorbent and is composed of multiple stages, and a rotary control valve 21 is installed at one side of the plate to enable opening and closing of the plate. Contact treatment tanks 31, 32, 33, 34, 35 which are in contact with the waste water while flowing; An air inlet 41 formed at one side of the lowermost contact treatment tank 31; By the air droplet contacting tank characterized in that it comprises a sample outlet port 51, 52, 53, 54 configured on one side of the treatment tank 31, 32, 33, 34, 35 of each stage Wastewater Treatment System for Continuous Heavy Metals