KR0139425B1 - Electrolytic wastewater treatment apparatus and method thereof - Google Patents

Abstract

The present invention relates to an electrolytic wastewater treatment apparatus and method for automatically treating wastewater.

The apparatus of the present invention is an electrolytic type having an electrolytic cell 2, a DC power supply 5 with electrodes, a means for introducing raw wastewater, and a conduit 31 for discharging the treated water. In the wastewater treatment apparatus, an electrolyte input tank 3 for introducing an electrolyte, a pH meter 6 for measuring the pH of the wastewater inside the electrolytic cell 2 and transmitting it to the control device 10, and a pH meter ( 6 and a pH regulator input tank 4 for introducing a pH regulator so that the pH measured in 6) reaches a predetermined pH set value, and the concentration of residual chromium (or cyan) in the wastewater is measured at a predetermined interval to the control device 10. A chromium (or cyan) detector 8 to transmit, a wastewater level detection device 9 for detecting the wastewater level inside the electrolytic cell, and a control device 10 for controlling each of the above components.

Electrolytic wastewater treatment method of the present invention, the step of introducing the raw wastewater into the electrolytic cell, the electrolyte input step, the step of measuring the pH of the wastewater in the electrolyzer to add a pH adjuster to reach a predetermined pH value, and performing electrolysis Stopping the electrolysis after measuring the residual chromium (or cyan) concentration in the wastewater, and stopping the operation for a period of time to separate the treated water and the sludge, and Discharging from the electrolyzer, discharging the upper treated water after discharge of the sludge, and continuing the air injection and wastewater circulation for smooth mixing of the wastewater during the electrolyte and pH adjusting agent addition step and the electrolysis step.

Description

Electrolytic Wastewater Treatment System and Method

1 is a schematic representation of a conventional chromium-containing wastewater treatment process.

2 is a schematic view of an electrolytic wastewater treatment apparatus of the present invention.

3 is a front view of the electrolytic electrode plate and the fixing device used in the present invention.

* Explanation of symbols for the main parts of the drawings

1: electrolytic wastewater treatment device 2: electrolyzer

3: electrolyte tank 4: pH meter

5: DC power supply unit 6: pH meter

7: ORP meter 8: chrome (or cyan) detector

9 wastewater level detection device 10 control device

16: air cylinder 19: magnetic pump

21, 22: electrode rod 23: nationwide rod fixed block

24: electrode plate 28, 32: pump

34: 4-way valve

The present invention relates to an electrolytic wastewater treatment apparatus and method, and more particularly, to an electrolytic wastewater treatment apparatus and method capable of automatically treating wastewater.

As the plating industry develops, the problem of environmental pollution due to the wastewater is serious, and various wastewater treatment technologies are urgently required to solve the problem. Since the plating plant is generally small and many items are produced in small amounts, the plating wastewater contains various heavy metals. Therefore, the plating wastewater contains toxic heavy metals.

In addition, in the case of wastewater discharged from the plating plant, even if the same processed product is processed in the same type and the same amount of plating solution tank, the components of the wastewater vary greatly according to various factors such as impurities, processes, and working methods. In many cases, the establishment of a wastewater treatment system does not provide adequate wastewater treatment results. Wastewater in conventional plating plants is, for example, by-products of base metals and metals used as anodes, metal suspended solids produced during surface treatment processes, and cyan ions due to cutting oils, emulsions, and cyanide from aeration in homogenization tanks. Acid alkali complex salts and the like include heavy metals (Cr, Cu, Zn, Cd) generated in the plating process, and chromates used as corrosion inhibitors of cooling water. In addition to the toxic heavy metals and cyanide, the plating wastewater contains chelating agents, surfactants, organic reducing agents, and the like, which are used to improve the quality of the plated products. Hazardous wastewater components and their causes in the general plating plant are shown in Table 1 below.

Conventional chromium waste water treatment in a plating plant is a reduction precipitation method, and Cr is reduced to Cr ³⁺ using a reducing agent such as ferrous sulfate, nitrous acid gas, sodium hydrogen sulfate, and the like at a pH of 3 or less, and then an alkaline substance such as lime is added thereto. It is neutralized and precipitated into trivalent chromium. The reaction scheme and process flowchart are as follows.

H ₂ Cr ₂ O + 6 H ₂ SO ₄ → Cr ₂ (SO ₄ ) ₃ + 2Fe ₂ (SO ₄ ) ₂ + H ₂ O

Cr ₂ (SO ₄ ) ₃ + 3Ca (OH) ₂ → 2Cr (OH) ₃ ↓ + 3CaSO ₄

Fe ₂ (SO ₄ ) ₃ + 3Ca (OH) ₂ → 2Fe (OH) ₃ ↓ + 3CaSO ₄

However, plating companies emit different kinds of wastewater for each process, but instead of collecting and treating them separately, they are mixed and concentrated.The treatment methods are merely physical treatment and chemical treatment. Therefore, the treatment effect is insufficient and the amount of sludge generated is not only to generate a second pollution, but also has a problem that the wastewater treatment facility occupies a large amount of treatment area, and the maintenance and repair cost of the wastewater treatment apparatus is excessive.

In addition, the conventional plating process wastewater treatment method is a physical and chemical treatment, the treatment effect is also insufficient, and has problems such as pH control of wastewater, reduction of heavy metals, flocculation of precipitation, flocculation aids, pH of effluent, etc. As shown in the schematic process diagram of FIG. 1, conventionally, a treatment tank such as a collection tank, a reaction tank, a precipitation tank agglomeration tank, a stabilizer tank, and the like is treated with chemicals such as sodium sulfite, caustic soda, hydrated lime, sulfuric acid, polymer coagulant, and ferrous sulfate. It is being discharged into wastewater through the water. Therefore, the processing area occupied by the processing equipment is large, and labor costs, fixed costs, and maintenance costs according to chemical costs are high.

Accordingly, the present invention has developed an electrolytic wastewater treatment apparatus as an automated treatment system to solve the problems in the conventional wastewater treatment apparatus and method, so that wastewater treatment costs and wastewater treatment facilities occupy significantly reduced wastewater treatment facilities. It is an object of the present invention to provide an electrolytic wastewater treatment apparatus and method capable of automatically and safely treating wastewater.

The electrolytic wastewater treatment apparatus and method of the present invention are particularly suitable for treating chromium wastewater or cyan wastewater having a high concentration of harmful heavy metals.

Electrolytic wastewater treatment is a method in which inorganic or organic materials electrolyze wastewater containing electrolytes so that suspended and dissolved substances, ie contaminants, in the wastewater are electrolyzed and removed simultaneously. It is a method of treating wastewater by using an electrochemical reaction by applying electrical energy to it. That is, the treatment of wastewater physically and chemically using the effects of metal precipitation, flocculation and sedimentation by electrochemical reactions such as dissolution, precipitation and oxygen and hydrogen generation of metals by redox reactions of the anode and cathode.

That is, soluble metal electrodes such as iron and aluminum are used, and electrolysis at the anode produces metal hydroxides, water dissociation and hydrogen gas are generated at the cathode, and the hydroxides aggregate, settle, or float. The chemical reactions at each electrode are as follows.

(anode)

Fe ―――― Fe²⁺+ 2e^- (Metal dissolution reaction)

Fe ---- Fe ³⁺ + 3e ^-

Fe²⁺―――― Fe³⁺+ e^- (Oxidation reaction)

_{4OH ---- 2H 2 O + O 2} + 4e -

(cathode)

^{_{H 2 O ---- H - + OH}} - ( water dissociation reaction)

_{^{2H + + 2e - ---- H 2}} ↑ ( the hydrogen generation)

So overall,

^{Fe 2+ + 2OH - ---- Fe (} OH) 2 ( the metal hydroxide formation reaction)

^{_{Fe (OH) 2 + OH -}} ---- Fe (OH) 3 ( a metal hydroxide formation reaction)

Reaction proceeds. Also,

Active dissolution reaction of metals;

^{Fe (Metal) ---- Fe 2+ +} 2e -

_{Fe (Metal) + H 2 O} ---- FeOH (aq) + 2e -

Oxidation reaction in solution of metal ions;

2Feoh (aq) + 1/20 ₂ + H ₂ O ―――― 2Fe (OH) ₂ (aq)

Hydrolysis reaction of metal complex ions;

Fe (aq) + H ₂ O ―――― FeOH ⁺ (aq) + H ⁺ (aq)

FeOH ⁺ (aq) + H ₂ O ------- 2Fe (OH) ₂ (aq) + H ⁺ (aq)

Fe (OH) ₂ (aq) ―――― HFeO ₂ ⁺ (aq) + H ⁺ (aq)

Hydroxo Polymer formation reaction in which the hydration complex is formed and hydrolyzed crosslinked product;

This is going on.

In addition, NaCL as an electrolyte shows the following reaction.

① Step 1

NaCl ---- Na ^{+ +} Cl ^-

② 2-step electrode reaction:

_{^{Anode: 2Cl - ---- Cl 2 + 2e}} -

Chlorine generation

Cathode: 2Na ⁺ + 2e ―――― 2Na

^{_{2Na + 2H 2 O ---- 2NaOH -}} + H 2

Full reaction

2NaCl + 2H ₂ O ―――― 2NaOH + Cl ₂ + H ₂

③ 3-step solution reaction:

^{_{Cl 2 + 2NaOH - ---- 2NaCl +}} ClO - + 2H 2 O

Hypochlorite

④ in alkaline

_{^{2HClO + ClO - ---- ClO 2 +}} 2H + + Cl -

^{Chloric acid}

Here, chlorine, hypochlorous acid, and chloric acid produced by NaCl (electrolyte) increase wastewater treatment efficiency due to strong oxidizing power, discoloration, and bactericidal action.

The electrolytic wastewater treatment apparatus of the present invention flows wastewater mixed with harmful heavy metals of a plating plant into an electrolytic cell equipped with a soluble electrode, adjusts the liquidity of the wastewater to weak acidity after adding an electrolyte, and flows an appropriate electrolytic current (direct current). It is a device configured to perform the electrolytic treatment, so that other metals such as Cu, Ni, Fe, Cd, etc. dissolved in the wastewater during the electrolytic treatment were treated like Cr and co-precipitated so that they can be treated simultaneously. In the wastewater treatment apparatus of the present invention, unlike the conventional electrolytic wastewater treatment apparatus, the optimum operating conditions are computerized and automatically processed in advance, thereby enabling continuous treatment of the wastewater.

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

2 is a schematic diagram of an electrolytic wastewater treatment apparatus according to a preferred embodiment of the present invention.

The electrolytic wastewater treatment device 1 includes an electrolyzer 2, an electrolyte inlet 3, a pH regulator inlet 4, a DC power supply 5, a pH meter 6, and a redox. An ORP (Oxidation-reduction potential meter) 7, a chromium (or cyan) detector 8, a wastewater level detection device 9, and a control device 10.

The electrolytic cell 2 is composed of a transparent container and is fixed on the base of the wastewater treatment apparatus 1. The electrolytic cell is configured to have a capacity of 125 L by connecting a hemisphere of the same material in the form of a flange to the bottom of a transparent acrylic tube having a diameter of 400 mm and a thickness of 10 mm, for example.

The electrolyte inlet tank 3 is a device for injecting an electrolyte such as salt (NaCl) to deliver the wastewater to be treated, and attaches the hopper 13 and the conduit 14 to the transparent tube 11. This is accomplished by installing a reciprocating piston 15 in the conduit 14 and an air cylinder 16 for actuating the piston 15 at one end of the conduit 14. The air cylinder 16 is operated by introducing or blocking air from the air pressure source (not shown) by the on / off valve 12 actuated by the control device 10 and the piston 15 in the conduit 14. The reciprocating motion is configured to push the electrolyte into the electrolytic cell 2.

The transparent tube 12 is, for example, an acrylic tube having a diameter (outer diameter) of 250 mm and a thickness of 8 mm, and the hopper 11 and the conduit 14 are made of stainless steel. The amount of the electrolyte introduced may be pre-programmed in the control device 10 so that only a predetermined amount is added according to the capacity of the electrolytic cell 2. It is preferable to use an open / close valve 17 connected to an air pressure source (not shown) having a maximum air pressure of about 7.03 kg / cm 2 (100 psi). The on / off valve 17 also introduces air through the conduit 18 through the conduit 18 into the interior of the electrolyzer 2 during the introduction of the electrolyte and pH regulator and during the entire electrolytic treatment to mix the electrolyte and pH regulator. And promote electrolytic operation.

The pH regulator input tank 4 is composed of a polyethylene container, has a built-in pH regulator, and controls the magnetic pump 19 controlled by the controller 10 based on the pH value measured by the pH meter 6. In operation, the pH regulator is introduced into the electrolytic cell 2 through the conduit 20. Since the normal pH of the wastewater is 1-2, the dosing is continued until the pH set point is 4-5, for example. The pH setting is set to be adjustable in various ranges in the control device 10, and the pH adjusting agent usually uses 10% NaOH.

The DC power supply 5 is a normal DC power supply, and a rotary switch is provided to be adjustable in eight steps up to a DC current of 100 A and a voltage of 50 V. This is to adjust the current and voltage according to the size and spacing of the pair of electrode plates 24 forming a pair of electrodes in the electrolytic cell through the three pairs of electrode rods 21 and 22 connected to the DC power supply 5. It is for. As best shown in FIG. 3, the pair of electrode rods 21 are horizontally fixed to the frame (not shown) of the DC power supply 5 and the other two pairs of electrode rods 22 are horizontally mounted. It is positioned to be substantially perpendicular to the rod 21. This is done by the electrode rod fixing block 23. That is, each of the electrode rod fixing blocks 23 is formed with the upper and lower holes staggered at right angles to each other to accommodate the two electrode rods 21 and 22. Fixing screws 23a and 23b are provided. Accordingly, the electrode rod fixing block 23 is slidable in the axial direction with respect to the electrode rod 21 fixed to the frame through the upper hole and fixed to the electrode rod 21 by the fixing screw 23a at the upper side. The gap between the pair of electrode rod fixing blocks 23 fixed to the electrode rod 21 is adjusted in accordance with the width of the electrode plate 24, so that the width of the electrode plate 24 is compatible. In addition, since the lower hole is formed to be staggered at right angles to the upper hole under the upper hole of the electrode rod fixing block 23 through which the electrode rod 21 penetrates, the electrode rod 22 is slid through this hole, so that the electrode It is possible to adjust the spacing between the electrode plates 24 fixed by bolts 25 at one end of the rod 22. The lower electrode rod 23 is fixed to the lower hole of the electrode rod fixing block 23 by a fixing screw 23b below the electrode rod fixing block 23.

The pH meter 6 and the ORP meter 7 respectively measure the pH and ORP values of the waste water and transmit them to the control device 10. In the control apparatus 10, according to the measured pH value, the magnetic pump 18 is operated as mentioned above, and the pH adjuster is thrown in from the pH adjuster input tank 4 until the pH value of wastewater reaches a predetermined value. . The electrolytic operation is stopped when the measured ORP value reaches a predetermined value. When the OPR measuring device 7 is provided with the chromium (or cyan) detector 8 described later, the chromium (or cyan) detector can measure and determine more precisely whether or not the treatment continues due to electrolysis of the wastewater. It may not be used.

The chromium (or cyan) detector 8 collects the wastewater during the electrolytic treatment from the electrolyzer 2 through the conduit 26 at predetermined time intervals for about 10 to 20 minutes, and reacts the reagent with a factory wastewater test method such as KSM 0111. After injection, color is absorbed and the absorbance is measured using a built-in UV / VIS spectrophotometer. The concentration of residual chromium (or cyan) is quantified according to the result. .

The wastewater level detection device 9 detects the water level of the wastewater introduced into the electrolytic cell 2 and transmits it to the control device 10. If it is determined that the water level is appropriate, the control device 10 stops the operation of the pump 28. To stop the inflow of wastewater. The wastewater level detection device 9 may use an electronic device for detecting only the water level and transmitting an electric signal corresponding thereto to the control device 10, and conduits the wastewater from the wastewater source in a mechanical manner as necessary. It may also be in the form of a lever switch to stop the operation of the pump 28 is operated to flow through. The inflow of the waste water is configured to be controlled by controlling the operation of the pump 28 by the signal of the wastewater level detection device 9, but in the case of electronics, it may be caused by a poor contact or a short circuit or in the case of a mechanical lever switch. Even if it becomes inoperable due to the fixing of the wastewater level detection device 9 due to a problem such as a foreign matter, the pump 28 is supplied to the control device 10 only for a predetermined time so that only the wastewater of a certain flow rate flows in. It is also possible to preset it to work. The pump 28 is a non-metallic material, such as polyflohylene-based, for example, for preventing corrosion along with the transfer of waste water and sludge, it is preferable to use an air diaphragm pump having a maximum air pressure of about 7.03 kg / cm 2 (100 psi).

The control device 10 is for controlling the entire process of the electrolytic wastewater treatment device, and may use, for example, an One Chip Microprocessor of the Intel 8051 series. The control device 10 is programmed to control all functions necessary for the process according to the order, time and concentration, such as inflow of raw wastewater, addition of electrolyte, addition of pH regulator, electrolysis, precipitation of treated water and separate discharge of supernatant and sludge. This input was configured to automatically unattend the entire treatment process.

The lower part of the electrolyzer 2 is provided with the discharge conduit 31 for discharging wastewater and sludge which were electrolytically processed, or circulating wastewater during electrolytic treatment. Waste water inside the electrolyzer flows through the pump 32 and into the four-way valve 34 through the conduit 33. The pump 32, like the pump 28, is preferably made of a non-metallic material, such as polypropylene, and uses an air diaphragm pump having a maximum air pressure of about 7.03 kg / cm 2 (100 psi). The four-way valve 34 is controlled at its outlet by the control device 10. According to the operation of the four-way valve 34, the entire flow passage includes a circulation passage in which wastewater discharged from the electrolyzer during operation is circulated to the electrolyzer through the conduit 35, and sludge deposited at the bottom of the electrolyzer after the electrolytic treatment is completed. A sludge discharge passage through which the sludge is discharged through the conduit 36 to discharge to the sludge collection tank (not shown), and the conduit 37 to discharge only the treated water inside the electrolyzer after the electrolytic treatment and sludge discharge to the treated water collection tank. It consists of a treated water discharge passage through which the treated water is discharged. If necessary, the treated water is discharged to a separate settling tank (not shown) to separate the sludge and the supernatant contained in the treated water, and the supernatant is reused as washing water through activated carbon tower and separated sludge and electrolytic Sludge initially collected during processing is disposed of.

A conduit 33 is provided with a branch conduit 38, to which the pressure relief valve 39 is attached. This caused the pressure relief valve to burst and stop when the pump was operated with the four-way valve disabled for the air cylinder and all of the circulation passage, sludge discharge passage and treated water discharge passage were locked.

When the electrolytic treatment of the wastewater is completed, the washing water is sprayed by the conduit 41 having a shower-shaped watering device attached to the distal end thereof from the washing water storage tank 40 controlled by the control device 10, thereby allowing the inside of the electrolytic cell 2 to be discharged. It is configured to wash.

In the method for treating wastewater in a plating plant using the electrolytic wastewater treatment apparatus of the present invention described above, first, harmful heavy metal plating wastewater in the plating plant is introduced into an electrolytic cell equipped with a soluble electrode, and an electrolyte is added to the liquid to treat the wastewater. After adjusting to weak alkalinity, it is a method of electrolytic treatment by flowing an appropriate electrolysis current (direct current).

Other metals such as Cu, Ni, Fe, Cd, etc. dissolved in the wastewater during the electrolytic treatment are treated like Cr and co-precipitated simultaneously.

The operating conditions were input to the microcomputer of the electrolytic wastewater treatment apparatus of the present invention in advance so as to enable continuous treatment of wastewater by automating the whole process.

① First, when the pump 28 is operated to start the operation, the raw waste water begins to flow into the electrolyzer 2 as a wastewater source. When the waste water is properly filled in the electrolyzer, the wastewater level detecting device 9 detects a predetermined position. This is transmitted to the control device 10, the control device stops the operation of the pump 28, thereby stopping the waste water inlet.

(2) After that, the control device 10 operates the on / off valve 12 to operate the air cylinder 16, thereby transferring a predetermined amount of powdered electrolyte (purified NaCl) from the electrolyte injection tank 3 to the electrolytic cell 2. Input.

③ In addition, by measuring the current pH value (pH 1 to 2) from the pH meter 6 and transmits it to the control device 10, the control device 10 is based on this to adjust the pH regulator input tank (4) In operation, a pH adjuster (10% NaOH) is added until the wastewater inside the electrolytic cell reaches a predetermined pH set point.

④ After that, perform electrolysis for a certain time (1 to 999 minutes) as already programmed in the control unit.

⑤ The ORP value or the concentration of residual chromium (or cyan) is measured by the ORP meter 7 or the chromium (or cyan) detector 8 during the electrolytic treatment operation, and if the predetermined ORP value or the predetermined residual concentration is reached, the control is performed. Transfer to device 12 stops electrolysis regardless of step ④. If the process of ⑤ precedes the process of ④, the remaining time of the process of ④ remains idle.

⑥ Rest the whole apparatus for a certain time (1 to 999 minutes) to separate the treated water and sludge.

⑦ After a certain time, the pump 32 and the four-way valve 34 is operated to discharge the precipitated sludge first through the conduit 36, and then discharge the treated water to the conduit 37.

⑧ For the smooth mixing of the wastewater during the above ②③④ process, the on / off valve 17 for injecting air and the pump 32 for wastewater circulation are continuously operated. The wastewater circulation is performed in a circulation passage through which the four-way valve 34 is operated to allow the wastewater to pass through the conduit 31, the pump 32, the conduit 33, the four-way valve 34 and the conduit 35.

The wastewater treatment process as described above is repeated a predetermined number of times (1 to 999 times, ∞).

By treating the plating waste liquid using the electrolytic wastewater treatment apparatus of the present invention, the following effects can be obtained.

First, by using the electrolytic wastewater treatment device can reduce the wastewater treatment cost, reduce the manufacturing cost of the plated product, second, minimize the amount of sludge generated, third, can recycle the valuable materials, Fourth, the treated water can be reused in the plating process.

Hereinafter, an embodiment in which wastewater is treated using the electrolytic wastewater treatment apparatus of the present invention will be described in detail. However, this embodiment does not limit the content of the present invention.

The overall specifications of the electrolytic wastewater treatment apparatus used are as follows.

Input garden: AC 220V

Electrolysis power capacity: DC 50V, 100A

Electrolyzer: Transparent acrylic tube (Φ 250 mm, 8T, 15L)

Electrolyte injection tank

-Drive part: Piston with air cylinder (maximum pressure 9.9 ㎏f / ㎠)

Hopper: Stainless Steel

-Body: clear acrylic (Φ 250 ㎜, 8T, 15L)

PH meter

-pH electrode: glass composite electrode

Indicator: Digital pH 0 to 14 (0.01 pH interval) measurement.

Min.scale: 0.01 pH

Transmission output: DC 4 ~ 20 mA, additional provision 250 Below

ORP measuring instrument

-ORP electrode: Metal composite electrode

-Indicator: Digital 0 Measuring 700 mV (20 mV steps),

Minimum scale: 200 mV

Transmission output: DC 4 ~ 20 mA, additional resistance: 250 Below

PH adjuster

-Driving part: Magnetic pump (maximum discharge amount: 8ℓ / min)

-Body: Polyethylene

Raw wastewater inlet and circulation discharge pump: Air diaphragm pump [Max. Air pressure: 7.03 ㎏ / ㎠ (100 psi)]

· electrode

-Soluble electrode: anode and cathode: iron plate electrode (flame-resistant steel plate SS41)

The test water was used 0.1 tons of plating wastewater (Cr, Cu, Ni, Zn plating) of the joint wastewater treatment plant of 14 companies in Namdong Industrial Complex, Jeil Plating Complex, Incheon, Korea. The plate size was (70 to 100) mm x 900 mm x 2 mm, and the wastewater treatment results when NaCl was used as the electrolyte are as follows.

According to the above results, it can be seen that, using the apparatus of the present invention, it is possible to treat wastewater containing a high concentration of heavy metal as described above with treated water containing a very low concentration of heavy metal.

Claims (8)

An electrolyzer 2, a DC power supply 5 with electrodes, means for introducing raw wastewater from the wastewater source into the electrolyzer 2, and a conduit for discharging the treated water from the electrolyzer 2 In the electrolytic wastewater treatment apparatus having a 31), the pH of the electrolyte input tank (3) for the introduction of the electrolyte, and the pH of the wastewater introduced into the electrolytic cell (2) is measured and transmitted to the control device (10) The meter 6, the pH adjuster input tank 4 for injecting a pH adjuster so that the pH measured by the pH meter 6 reaches the pH set value set in the control apparatus 10, and inside the electrolytic cell at predetermined time intervals. A chromium (or cyan) detector 8 for measuring the concentration of residual chromium (or cyan) in the wastewater of the wastewater and sending it to the control device 10, and a wastewater level detection device 9 for detecting the wastewater level in the electrolyzer. And a control device 10 for controlling each of the components. Electrolytic water treatment device, characterized in that 2. The electrode of claim 1, wherein the electrodes of the DC power supply 5 are horizontally perpendicular to the pair of electrode rods 21 fixed horizontally to the frame of the DC power supply 5 and to the pair of electrode rods 21. Two pairs of electrode rods 22 positioned at the ends and vertically fixing the electrode plate 24 at one end thereof, and the pair of other electrode rods 22 with respect to the pair of electrode rods 21 at right angles. Electrolytic wastewater treatment apparatus comprising an electrode rod fixing block (23) for slidably fixed in the axial direction. The pump 32 according to claim 1 or 2, wherein the pump 32 circulates the wastewater in the electrolytic treatment inside the electrolytic cell and delivers the electrolyzed wastewater and sludge to the four-way valve 34 through the conduit 33, and the pump And a four-way valve 34 for selectively communicating one of the passages extending from each of the conduits 35, 36, 37 to the electrolyzer and the sludge collection tank and the wastewater collection tank via the conduits 35, 36, 37. Electrolytic wastewater treatment apparatus, characterized in that. 4. The apparatus of claim 3, further comprising means for introducing air through conduit 18 by control of control device 10 to facilitate mixing and electrolytic operation of electrolyte and pH regulator within electrolyzer 2. Electrolytic wastewater treatment apparatus, characterized in that. 5. An electrolytic wastewater treatment apparatus according to claim 4, further comprising an ORP meter (7) for measuring and transmitting the redox potential (ORP) of the wastewater inside the electrolyzer at predetermined time intervals to the control device (10). . In the electrolytic wastewater treatment method, the step of introducing the raw wastewater into the electrolyzer, the step of introducing the electrolyte into the electrolyzer, the step of measuring the pH of the wastewater in the electrolyzer to add a pH adjuster to reach a predetermined pH value, Performing electrolysis, stopping the electrolysis after measuring the residual chromium (or cyan) concentration in the wastewater and stopping the operation for a certain time to separate the treated water and sludge after stopping the electrolysis And discharging the sludge from the electrolytic cell, and discharging the treated water after discharge of the sludge. 7. The method of claim 6, further comprising continuing air injection and wastewater circulation for smooth mixing of the wastewater during the electrolyte and pH adjuster input and electrolysis steps. The electrolytic wastewater treatment method according to claim 6 or 7, further comprising the step of stopping the electrolysis if the redox potential (ORP) of the wastewater is reached to reach a predetermined ORP value.