KR20020004661A - Waste Water Treatment Apparatus using Cylindrical Electrocoagulated Equipment - Google Patents

Abstract

PURPOSE: A wastewater treatment equipment using cylindrical electro-coagulator, which is able to treat a large amount of wastewater at a low cost in a shortened reaction time, thereby reducing sludge discharge with not using any inorganic coagulant agent, is provided. CONSTITUTION: The system comprises a pre-treatment step, an electrocoagulation device(20) and a settling basin(30). At the pre-treatment step, water with the pH adjusted to 5 to 6 by feeding acid or alkali and ozonized to 15 ppm by ozone of ozone generator(16) in a raw water tank(10) is pumped to the electrocoagulation device(20) through a sand filter(18). In the electrocoagulation device(20), cathode bar(24) and anode bar(26), which are made of aluminum material, are installed at positions spaced apart and applied by alternations of 200 times per minute by direct current of 400A at 15V from electrical power generator(28) to discharge Al¬+3 ion forming coagulated floc in wastewater.

Description

Wastewater Treatment Apparatus using Cylindrical Electrocoagulated Equipment

The present invention relates to a wastewater treatment apparatus, and more particularly, a cylindrical electric machine for treating a large amount of wastewater at a low price while reducing the installation area, the reaction time and the amount of sludge generation, and increasing the treatment efficiency than the chemical treatment method using the inorganic coagulant. It relates to a wastewater treatment apparatus using a flocculator.

The conventional chemical treatment of wastewater using inorganic coagulants is mainly used to remove turbidity. Currently, coagulation and precipitation methods such as inorganic coagulants and polymer coagulants of aluminum and iron salts are in progress. For example, the related art is based on ferric salts such as alum, caustic soda and hydrated lime, ferric chloride, ferric sulfate, ferric sulfate, and the like. BOD, COD, color causing substances and other heavy metals in wastewater are formed by artificially forming a scum using various kinds of organic and inorganic coagulants such as aluminum, PAC, PAS, etc. Remove

In this case, however, in general, the size of the existing flocculation sedimentation tank must be about 6 hours or more of the amount of inflow to remove the suspended substances entering the wastewater.

In addition, the unit process of the apparatus should be complicated by the raw water tank, the chemical mixing tank and the coagulation sedimentation tank.

Therefore, in the conventional treatment method using inorganic coagulant, the amount of coagulant input is related to the removal efficiency of pollutants, and the amount of coagulant is excessively input, and the amount of sludge generated is large.

In addition, the existing flocculation sedimentation method is a precipitation method by natural sedimentation rate, so the precipitation rate is slow, the treatment area must be large, and the reaction time is long.

The technical field of the present invention is to develop a system for wastewater treatment by applying an electrochemical concept. Electrochemical water treatment systems using electrodes have been studied in the United States, where wastewater is treated using iron and aluminum as electrode materials. In this case, electrolytic agglomeration using aluminum electrodes increases the color removal rate of the wastewater by forming aluminum hydroxide flocs, reduces the reaction time and the installation area while reducing the amount of sludge, and thus can treat a large amount of wastewater at low cost. to be.

Electrocoagulation causes chemical reactions by using soluble electrodes such as aluminum and iron at the anode and continuously supplying metal cations around the anode to generate direct ions by electrolysis. The metal cations produced are convection and diffused by the force and concentration gradient of the electric field, and are neutralized by being electrically coupled with particles such as colloids. . (Cenkin, V.E. and Belevttsev, A.N., "Electrochemical treatment of industrial wastewater", Effluent and water treatment J., July, 243-247 (1985))

However, the precipitation method by electrocoagulation is effective in the case of thin electrode plate in the process of effectively inducing coagulation and precipitation of ionized aluminum ions and organic matter in wastewater by periodic replacement of positive and negative electrodes. Since electrode plate replacement (30 days in the past) can be frequent, the effect can be halved if it is not accompanied by technical development and management efforts to extend the life of the electrode plate using aluminum.

In addition, the wastewater has to have a narrow gap (less than 1cm) in order for the wastewater to be treated more than 40%. There is a limit of development. Therefore, it is necessary to develop a device capable of changing the shape of the electrode plate and introducing a large amount of wastewater.

Therefore, an object of the present invention is to solve the above problems, the installation area as well as the reaction time and sludge generation amount can be reduced and the treatment efficiency compared to the chemical treatment method by the inorganic coagulant, while processing a large amount of waste water at a low price cylindrical Provided is a wastewater treatment apparatus using an electrocoagulator.

1 is a schematic diagram showing the overall process of the wastewater treatment apparatus according to the present invention,

2 is a front view and a plan view showing the internal structure of the cylindrical electroaggregator in FIG.

Figure 3 is a graph showing the throughput according to the change in distance between the electrodes.

4 is a graph showing the results of treatment in the main process.

Explanation of symbols on the main parts of the drawings

10: raw water tank 12: pH controller

14 air pump 16 ozone generator

18: sand filter 20: electrocoagulator

22: electrode plate 24: negative electrode rod

26: positive electrode 28: power generator

30: sedimentation tank

In order to achieve the above object, the present invention collects the wastewater collected in the raw water tank 10 through the appropriate pretreatment means and reaches the electrocoagulator 20 to electrically flocculate the suspended matter and the dissolved organic and inorganic materials in the sedimentation tank 30. In the processing system to be collected: the pretreatment means includes a pH regulator 12, an air pump 14, an ozone generator 16, a sand filtration tank 18, and the electroaggregator 20 is made of aluminum. The negative electrode 24 and the positive electrode 26 are provided at equal intervals, and are connected to a power generator 28 for applying alternating DC power to ionize Al ⁺³ ions of the electrode in the wastewater to form a flocculation product. It features.

At this time, the pretreatment means maintains a pH of 5 to 6 through the pH regulator 12, and maintains the concentration of the ozone injection of the ozone generator 16 at 15 ppm.

In addition, the electroaggregator 20 has a structure in which a plurality of positive electrode electrodes 26 are disposed radially around the negative electrode electrode 24 in the center, and polarity is alternately changed 200 times per minute under a DC voltage of 15V and a current of 400A.

In this way, the aluminum electrode is overlapped with multiple layers of aluminum rods inside the cylindrical tube, and the electrode inside the aluminum rod is positively charged by the electrochemical reaction using the negative electrode and the small aluminum rod around the central aluminum rod as the positive electrode. (Iii) Metal ions generated at the pole plates act as nuclei to form stable aggregates and finally precipitate into metal oxides. In other words, when a current is applied to the wastewater, metal ions generated at the electrode react with the suspended particles, the emulsified particles, the insoluble materials, and the like to produce a solid aggregate and finally facilitate the precipitation.

The advantage of the present invention is that the floc flocculates the organic matter and is floated by the hydrogen generated during the cathode reaction, so that the rapid stirring process is unnecessary and the reaction time can be reduced.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a schematic diagram showing the overall process of the wastewater treatment apparatus according to the present invention, Figure 2 is a front sectional view and a plan view showing the internal structure of the cylindrical electroaggregator in FIG.

In FIG. 1, a device for treating domestic sewage or livestock wastewater is devised, and after adjusting the pH using H ₂ SO ₄ in a pH controller 12, sand filtration tank 18 to remove suspended solids and contaminants. After passing through the electrocoagulator 20. In order to adjust the pH to maintain a constant pH by linking the metering pump into the raw water tank 10, the stirring of the raw water tank to maintain a stirring speed of 250rpm, to maintain a constant water level in the raw water tank (10). The device is configured to pass through the electrocoagulator 20 in the state in which the solids of the wastewater are removed from the raw water tank 10 through the sand filtration tank 13, and the power source used for the electric device of the present invention is a direct current power generator. Supply via (28). To measure the amount of current during the electrical coagulation process, an AXIOM board is mounted on the computer and the current strength is monitored to calculate the integral.

In addition, the ozone generator 16 is interlocked with the air pump 14 to generate ozone using air, and the concentration of ozone generated is 1 to 20 mg. The ozone generator 16 serves to change the chemical properties so that the raw water introduced into the raw water tank 10 is ozonated to facilitate the removal of organic matter in the electrocoagulator 20. In this way, the treated water passing through the electrocoagulator 20 is discharged to the pump through the outlet 12, the sedimentation sludge settled through the settling tank (30).

In this case, in FIG. 2, the electroaggregator 20 has a negative electrode rod 24 at the center of the cylindrical electrode plate 22 and radially mounts the positive electrode rod 26 around the negative electrode rod 24. The positive electrode 26 is made of aluminum. The electric power source is to allow the pole electrode to be replaced with 200 pole electrodes per minute by a tachometer of the power generator 28, and the DC voltage is 15V and the current is 400A. The distance between the negative electrode rods 24 and the positive electrode rods 26 of aluminum is 3 cm, the inflow rate of waste water is maintained at 27 L / min.

The electroagglomerator 20 reacts by supplying metal cations from the soluble electrode of aluminum to the anode around the anode, and the generated metal cations change the force and concentration gradient of the electric field when the positive and negative electrodes are changed between the electrodes. By convection and diffusion, the particles are electrically coupled to particles such as colloids and neutralized to allow aggregation. In this case, the influent wastewater can form aggregates in a short time.

More specifically, the electrode used for electrocoagulation is eluted in the ionic state because it is oxidized during the electrolytic reaction, Al (OH) ₃ which can act as a coagulant by combining with OH ^- generated by the electrolysis of water in the negative electrode By generating the aggregates, contaminants such as inorganic and organic matter are aggregated and precipitated. This reaction is as follows.

Al ---> Al ⁺³ + 3e ^-

^{Al +3 + 3OH - ---> Al} (OH) 3

That is, when hydrogen is generated from the cathode and aluminum is used as the anode material, Al ⁺³ ions generated by the oxidation of the anode react with OH ^- ions generated at the cathode to form hydroxides, adsorbing contaminants in the solution. Remove by precipitation. The solid sludge produced at this time has an advantage that the amount is very small compared to the sludge generated by other chemical treatment process, and is used in various industrial wastewater treatment such as organic matter removal and decolorization in terms of the effect of electrolytic treatment.

The electrolytic coagulation process showed stable treatment under the condition of 1500C / L charge and 7.8mA / cm ² current density at pH5. In this case, removal efficiency of COD, TOC, and SS turbidity is 40, 30, 85, 80%. .

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

<Example 1>

Table 1 shows a comparative analysis of the chemical flocculation using the inorganic coagulant Alum (Al ₂ (SO ₄ ) ₃ ) and the wastewater treatment effect of the cylindrical electrocoagulator 20 of the present invention. In this embodiment, the positive and negative electrode rods 24 in the center of the positive electrode 26 and the electrode plate 22 were replaced 200 times per minute, and the DC voltage was 15V and the current was 400A. . Wastewater used for this experiment is domestic wastewater generated by Hyundai Heavy Industries.

Comparison of Electro-aggregation and Chemical Coagulation for Improving Treatment Effect of Domestic Sewage Item Raw → ↓ Chemical coagulant Electric cohesive COD SS COD SS density (mg / l) Removal rate (%) density (mg / l) Removal rate (%) density (mg / l) Removal rate (%) density (mg / l) Removal rate (%) enemy 200 - 250 - 200 - 250 - Sand filtration 140 - 237 5 140 - 237 5 Flocculation method chemistry 70 65 35.6 85 - - - - Electricity - - - - 52 45 11.9 95 Sedimentation tank 21 70 28.5 20 15.6 70 9.5 20

For this experiment, the specifications of the electroaggregator 20 are the diameter of the negative electrode rod 24 in the center is 3cm, the diameter of the adjacent positive electrode 26 is 2cm, the outer diameter of the electrode plate 22 is maintained 20cm The spacing between poles was 3 cm, and the inflow rate of wastewater was maintained at 27 l / min.

The results in Table 1 show that the pH is 6, and the solubility of the ionized aluminum varies depending on the change in pH, resulting in a change in throughput. As shown in Table 2, solubility increases as pH increases generally, and the aggregation effect falls.

COD removal efficiency according to pH change in electrocoagulation device pH change COD removal rate (%) 5 40 6 45 7 36 8 32

<Example 2>

Experimental results of the first and second treatments of electrocoagulation using livestock wastewater collected from livestock farms in Gimhae are shown in Table 3 below. As shown in Table 3, the results of the second and subsequent treatments of electrocoagulation are increasing in the case of other analysis items except dissolved organic and inorganic substances.

Results of the 1st and 2nd Treatment of Livestock Wastewater Using Electrocoagulant Item enemy 1st treatment water Secondary treatment water % Removal CODcr (mg / ℓ) 1248 960 768 39 TOC (mg / ℓ) 84 67 68 19 SS (mg / ℓ) 260 63 48 TDS (mg / ℓ) 4210 3920 3810 10 Turbidity (NTU) 47 18 3 92 Chromaticity (CU) 528 71 71 87 NH ₄ -N 565 499 462

<Example 3>

Experiments were conducted to determine the effect of livestock wastewater treatment by electrode spacing at currents 3A and pH 5. 3 shows the effect on the COD _cr removal efficiency due to the electrode spacing when the electrode spacing is changed to 0.5 to 4 cm. As a result, the COD removal efficiency decreased as the interval between the aluminum poles of the positive and negative electrodes became wider, and the processing efficiency was about 45% at the narrowest electrode interval of 0.5cm and the interval was 3cm. The treatment efficiency was 35%, and the treatment effect did not drop significantly when it exceeded 3cm. In view of the above results, the narrower the interval between the aluminum rods, the higher the treatment effect and the lower the flow rate of the flow rate in the cylindrical tube. Therefore, the interval between the actual aluminum rods is preferably 3 cm.

<Example 4>

If the amount of current flowing for a unit time is changed with respect to the electrode area, the current density is changed and the formation of flocs on the electrode surface causes contact with hydrogen, which affects the removal of organic matter. Here, the current measurement is based on the AXIOM current measurement plate mounted on a computer to monitor the current strength. Table 4 below shows the COD removal rate according to the change of the current density and the charge amount, and as the current density decreases, the COD removal rate increases for the same charge amount. Since the COD removal rate does not increase significantly above the charge amount of 1500 C / L, the organic matter that can be removed by aluminum electrocoagulation is almost removed. In the case of 3A, the COD removal rate decreases when the current amount is operated at a charge amount of 2,500C / L. As the current amount increases, the generation rate of hydrogen gas generated on the cathode surface increases, disturbing the generated floc layer and regenerating the free organic matter. This is because it is dispersed. Therefore, in order to increase the COD removal rate, the charge amount must be kept low and the current amount must be maintained.

COD removal effect according to current density Charge amount (C / L) Current density (A) 500 1500 2500 0.5 10% 24% 21% One 15% 28% 29% 2 5% 22% 22% 3 One % 20% 14%

Example 5

After ozone treatment of the wastewater source with 15 ppm of ozone injected into the ozone generator 16, the electrocoagulation treatment resulted in an increase in the wastewater treatment efficiency due to the change in chemical properties of organic matter in the wastewater by ozone. As shown in FIG. 4, the result of electrocoagulating the raw water having the COD of 810 ppm of the dyeing wastewater and the electrocoagulating after ozone treatment showed that the COD treatment efficiency increased more than 30%.

In the present invention, the COD _cr and SS removal efficiencies of 45% and 85% of COD _cr and SS are 15% higher than those of the chemical coagulation method, respectively. In addition, electrocoagulation of the dye wastewater after ozone treatment resulted in a 30% increase in treatment results.

As a result, installation area and reaction time are reduced, and since no chemical flocculant is added, sludge generation is naturally reduced. Thus, it is possible to treat a large amount of waste water at a low price while improving treatment efficiency than the chemical treatment method using inorganic coagulant. .

According to the above configuration and operation, the present invention can reduce the reaction time and sludge generation amount as well as the installation area, and can increase the treatment efficiency compared to the chemical treatment method using the inorganic coagulant, while treating a large amount of wastewater at a low price.

It is apparent to those skilled in the art that the present invention is not limited to the described embodiments, and that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modifications or variations will have to belong to the claims of the present invention.

Claims (3)

In the system for treating the waste water collected in the raw water tank (10) through the appropriate pretreatment means and reaches the electrocoagulator (20) to electrically flocculate the suspended matter and dissolved organic and inorganic materials and then recollect in the settling tank (30): The pretreatment means is provided with a pH regulator 12, air pump 14, ozone generator 16, sand filtration tank 18, The electroaggregator 20 is provided with negative electrode rods 24 and positive electrode rods 26 made of aluminum at equal intervals, and is connected to a power generator 28 for applying alternating DC power to Al ⁺³ ions of the electrode. Wastewater treatment apparatus using a cylindrical electrocoagulator, characterized in that the ionized in the wastewater to form a flocculation product. The method of claim 1, The pretreatment means maintains a pH of 5 to 6 through the pH regulator 12, the wastewater treatment apparatus using a cylindrical electrocoagulator, characterized in that to maintain the concentration of the injection ozone of the ozone generator 16 to 15ppm. The method of claim 1, The electroaggregator 20 has a structure in which a plurality of positive electrode electrodes 26 are radially disposed around a negative electrode electrode 24 in the center, and polarity is alternately changed 200 times per minute under a DC voltage of 15 V and a current of 400 A. Wastewater treatment device using a cylindrical electrocoagulator.