KR100299508B1 - Electrochemical wastewater treatment method and apparatus therefor - Google Patents

Abstract

PURPOSE: Provided is an electrochemical wastewater treatment method, which can perform liquid/solid separation effectively with even less power consumption and electrode consumption. CONSTITUTION: The apparatus(100) for electrochemical wastewater treatment comprises electrolysis part(150) including a scrapper and an AC electrolysis tank; reaction part(170) in which various chemicals are injected into electrolyzed wastewater; coagulation part(180) for liquid/solid separation. The AC electrolysis tank is characterized in that a pair of subsidiary electrode are parallel grounded to the both sides of main electrode. In the method, NaCl is added to reduce power consumption by increasing electro conductivity, and separated oil is coagulated by aluminum hydroxide released from electrode.

Description

Electrochemical Wastewater Treatment Method and Apparatus

The present invention relates to a wastewater treatment method and apparatus for purifying various wastewater, and more particularly, to a wastewater treatment purification method and apparatus for purifying wastewater using an electrochemical reaction.

In order to prevent water pollution, it is a common task of industrial society to clean up various industrial wastewater and domestic sewage. The constituents of the wastewater vary greatly depending on the type of pollutant, and various treatment methods are used according to the various constituents of the wastewater. Such treatments can be roughly divided into solid-liquid separation, biochemical treatment, and physicochemical treatment. In general, wastewater treatment facilities are composed of the above three types of treatments according to the composition and characteristics of the wastewater to be treated. Among them, the physicochemical treatment is a method that we commonly see, such as adding chemicals to chemical reactions, stirring mechanically, or separating suspended solids or sediments.

The electrochemical treatment method of the present invention is also a kind of physicochemical treatment method, and is a method of floating separation or sedimentation separation by making water-soluble contaminants in wastewater into insoluble compounds using electric energy. Conventionally, the electrochemical treatment method has high utility voltage, high power consumption, fast wear rate of electrodes, and is difficult to maintain and manage.

The present invention has been made to solve the above-described problems, and to provide an electrochemical wastewater treatment method capable of adapting to various kinds and properties of contaminants in wastewater, responding to low electric energy of low voltage, and not having abrasion of electrodes. will be.

In addition, the present invention is intended to prevent the electrode from being contaminated due to contaminants in waste water, products of electrolytic reactions, and the like, and falling into an inoperable state.

In addition, the present invention is to provide a wastewater treatment apparatus that can purify the wastewater containing contaminants of various types and properties by using the above method.

Figure 1 is a schematic diagram showing the configuration of the wastewater treatment apparatus according to the present invention

2 is a schematic diagram showing an example of an electrode for alternating electrolysis of the wastewater treatment apparatus shown in FIG.

3 is a schematic diagram showing another example of the electrode for alternating current electrolysis of the wastewater treatment apparatus shown in FIG.

According to this invention for achieving the above object, there is provided a wastewater treatment apparatus for purifying the wastewater by flotation and sedimentation of the contaminants in the wastewater by electrochemically reacting the wastewater. The wastewater treatment seawater includes an electrolytic unit for electrolyzing the wastewater, a reaction unit for adding various additives to the electrolyzed wastewater and reacting physicochemically, and an agglomeration unit for coagulating the product by statically maintaining the wastewater after the reaction.

In addition, according to the present invention, there is provided a wastewater treatment method for purifying wastewater by flotation and sedimentation of contaminants in the wastewater by electrochemically reacting the wastewater. The wastewater treatment method includes an electrolytic step of electrolyzing wastewater, a reaction step of adding various additives to the electrolyzed wastewater, and a physicochemical reaction, and a coagulation step of agglomerating the product by statically maintaining the wastewater after the reaction.

The above and other objects and details of the invention will become apparent from the description of the embodiments set forth below.

EXAMPLE

Hereinafter, with reference to the drawings will be described in detail a preferred embodiment of the electrochemical wastewater treatment method and apparatus according to the present invention.

1 schematically shows an embodiment of a wastewater treatment apparatus according to the present invention.

The wastewater treatment apparatus 100 according to this embodiment includes a wastewater inflow unit 110 through which wastewater to be treated is received, an additive supply unit 130 supplying additives to be introduced in a step-by-step treatment process, and an electrolytic unit electrolyzing the introduced wastewater. 150, a reaction unit 170 for putting various additives into the electrolyzed wastewater to react physicochemically, a flocculation unit 180 for agglomerating the product by statically maintaining the wastewater after the reaction, and collecting in a stepwise treatment process. The wastes are separated into solid-liquid separators (190: 固液 分離 部) for separating solids and liquids.

The additive supply unit 130 includes a plurality of containers 131, 132, 133, and 134 that can contain additives to be added to each step of the process, for example, NaCl, poly aluminum chloride (PAC), NaOH, and a high molecular compound. The vessels 131, 132, 133, and 134 are connected to supply lines L31, L32, L33, and L34 which lead to a corresponding treatment process.

The wastewater inlet 110 includes a wastewater storage tank 111 for storing wastewater to be treated. The waste water bottom emphasis 111 keeps the waste water supplied through the waste water inlet pipe 112 almost static to sink the contaminants present in the suspended state. In order to maintain the static state of the waste water, the waste water inlet pipe 112 is preferably connected to the lower side of the waste water storage tank 111, it is preferable that the shut-off valve (V12) is installed in the pipeline.

The upper and lower two outlets are installed in the wastewater storage tank 111, and the upper outlet 113 sucks up and down wastewater including only floating materials having a relatively low specific gravity while moving up and down along the water surface, and the lower outlet 114 is a wastewater storage tank 111. It is installed underneath to suck up wastewater containing pollutants with a relatively high specific gravity.

The line L13 connected to the upper outlet 113 is branched into a line L131 leading to the DC electrolytic bath 151 of the electrolytic unit 150 and a line L132 leading to the AC electrolytic bath 152.

The line L14 connected to the lower outlet 114 is also branched into a line L141 leading to the DC electrolytic bath 151 of the electrolytic unit 150 and a line L142 leading to the AC electrolytic bath 152, and each line L141. , L142 is provided with filters 115 and 116 for filtering contaminants exceeding a predetermined size. In this embodiment, the filters 115 and 116 filter out particles larger than 100 μm. In addition, mixers 117 and 118 are installed in the lines L141 and L142 of the filters 115 and 116 to mix NaCl supplied from the NaCl container 131 of the additive supply unit 130 to the filtered waste water. do. In the lines L14, L141 and L142 from the lower outlet 114, flow control valves V14 and check valves V141, V143, V144, V145 and V146 are provided.

The electrolytic unit 150 includes a DC electrolytic cell 151 for delivering wastewater using DC electric energy, and an AC electrolytic cell 152 for delivering waste water using high frequency AC electric energy. Electrolytic electrolysis takes place, and electrolytic electrolysis takes place in the AC electrolytic bath 152.

NaC1 added to the wastewater before being put into the electrolytic cells 151 and 152 is

Presence in the form of Na ⁺ and Cl ⁻ improves the conductivity of waste water, and the improved conductivity reduces power consumption by lowering the operating voltage and current. Ci ⁻ also aids in the oxidation of organics in the waste water.

When the component of the wastewater flowing out of the upper outlet 113 of the wastewater storage tank 111 is preferably electrolytically transmitted, the shutoff valve V131 of the line L131 leading to the direct current electrolytic tank 151 is opened and the AC electrolytic tank ( The valve V132 of the line L132 leading to 152 is closed, and the valves V131 and V132 are opened and closed in reverse when it is desirable to be electrolytically reduced.

In addition, when the component of the wastewater flowing out of the lower outlet 114 of the wastewater storage tank 111 is preferably electrolytically transmitted, the shutoff valve V143 of the line L141 leading to the direct current electrolytic tank 151 is opened and the AC The valve V144 of the line L142 leading to the electrolytic cell 152 is closed, and the valves V143 and V144 are opened and closed in reverse when it is desirable to be electrolytically reduced.

In the electrolytic processes in the DC electrolytic bath 151 and the AC electrolytic bath 152, the waste water of the emulsion (emulsion liquid) property is separated into water and oil. The separated fraction is agglomerated by aluminum hydroxide, a compound of aluminum ions eluted from the electrode, to rise above the surface of the water. These wounds are scraped off by scrapers 155 and 156 and collected in the oil sump tanks 157 and 158. The collected oil is sent to solid-liquid separator 190 along lines L57 and L58.

The molecular formula of PAC added to the electrolyzed wastewater is Al ₂ (OH) _n Cl _6-n and this compound is aluminum sulfate [Al ₂ (SO ₄ ) ³ 18H ₂ O] or ferric sulfate [Fe ² (SO ₄ ) _n ] Can be replaced with

The wastewater electrolyzed in the electrolyzers 151 and 152 is sent to the reaction unit 17 along the lines L51 and L52, and sulfuric acid supplied along the line L32 from the PAC tank 132 of the additive supply unit 130 is en route. In the waste water, shutoff valves V321 and V322 are installed in the sulfuric acid supply line L32.

The waste water introduced into the reaction tank 171 of the reaction unit 170 is mixed with NaOH and the polymer supplied from the NaOH tank 133 and the polymer tank 134 of the additive supply unit 130. The reactor 171 is provided with a stirrer 172 to allow the waste water and additives to be quickly and evenly mixed. In addition, the waste water inlet 173 is preferably installed in the upper portion of the reaction tank 171 to maximize the fluidity of the waste water in the reaction tank (I71). When the additive is added to the waste water, the electrolytic contaminants in the waste water react with the additive to form an insoluble compound, and the large particles among such insoluble products are immediately precipitated to the bottom of the reactor 171. This precipitate is discharged through the precipitate discharge port installed in the bottom of the reaction tank 171 is sent to the solid-liquid separator 190 along the line (L71). It is preferable that a shutoff valve V71 is provided in the line L71.

Sulfuric acid for removing phosphorus may be added to the wastewater in the reactor 171.

The waste water mixed with the additive in the reaction tank 171 is sent to the agglomeration part 180 through the outlet 174 installed on the upper portion of the reaction tank 171. In the flocculation tank 181 of the flocculation unit 180, the waste water is stably maintained while aggregation of the insoluble compounds suspended in the particulate state. Insoluble compounds which have grown to aggregate are precipitated to the bottom of the flocculation tank when they reach an appropriate size. This precipitate is discharged through the precipitate discharge port installed in the bottom of the reaction tank 181 is sent to the solid-liquid separator 190 along the line (L81). It is preferable that a shutoff valve V81 is provided in the line L81. The wastewater inlet 182 of the flocculation tank 181 is preferably installed at the bottom so that the inflow of wastewater does not damage the stable state in the flocculation station 181.

NaOH is added to the wastewater in the flocculant 181 to improve the cohesive force of the polymer compound by controlling the acidity (pH) of the wastewater. As the polymer compound introduced into the coagulation tank 181, a polyacrylamide compound having a white powder is mainly used.

The water in the coagulation bath 181 in which the insoluble compound is deposited while maintaining a stable state, in particular, the water near the surface of the water is purified water to a level of general fresh water with little contamination. The purified water is sent to the treated water tank 197 through an outlet installed in the upper part of the coagulation tank 181, and the treated water is added to the stream after the addition of environmentally friendly acid or alkali to adjust the acidity (pH). It is discharged or recycled into various waters.

On the other hand, the solid-liquid separator 190 includes a housing 191 and the filter bag 192 therein. Flotation and sediment collected in the step-by-step process is put into the filter bag 192 is separated into a solid and a liquid. The separated solids and liquids are appropriately treated according to the components thereof, and in particular, the liquid is repeatedly discharged in the stream or mixed in the wastewater introduced into the wastewater storage tank 111 of the wastewater inlet 110 and subjected to all processes. .

Hereinafter, a detailed structure of the electrodes 153 and 154 used in the electrolytic baths 151 and 152 of the wastewater treatment apparatus 100 of this embodiment will be described with reference to FIGS.

2 shows an example of an electrode used in the AC electrolytic bath 152. The electrode according to this example includes two main electrodes 521 and 522 in parallel and two sub electrodes 523 and 524 arranged in parallel on one side of each of the main electrodes 521 and 522. The main electrodes 521 and 522 are titanium platinum electrodes, alumina electrodes, carbon electrodes, iron electrodes or ferrite electrodes. The sub electrodes 523 and 524 are alloys of aluminum (Al), zinc (Zn) and magnesium (Mg). Electrode.

In the electrolytic process, the main electrodes 521 and 522 are connected to a high frequency AC power supply 525 of 400 Hz to 40 KHz, and the sub electrodes 523 and 524 are grounded.

If the secondary electrodes 523 and 524 are contaminated by contaminants in the waste water or precipitates in the electrolytic process after a predetermined time of electrolysis, the electrical power of the power supply 525 and the main electrodes 521 and 522 is switched using the switches S21 and S22. The connection is disconnected and the power source 525 and the negative electrodes 523 and 524 are connected to each other, and the ground of the negative electrodes 523 and 524 is cut off using another switch S23 and S24. Then, electrolysis by the sub-electrodes 523 and 524 occurs while the main electrodes 521 and 522 are left unattended, whereby contaminants adhering to the sub-electrodes 523 and 524 are dissolved in water and the sub-electrodes 523, 524 is cleaned.

3 shows another example of the electrode used in the AC electrolytic bath 152. This electrode includes two main electrodes 526 and 527 arranged in series and two sub electrodes 528 and 529 arranged in parallel, one on each side of the main electrodes 527 and 528. The electrode according to this example differs only from the arrangement of the other electrodes and the main electrodes 526 and 527 in the example described above, and the other configurations and operations are the same.

Representative electrolytic reactions occurring in the AC electrolytic bath 152 having electrodes as shown in FIG. 2 or FIG. 3 are shown in Chemical Formula 1 or Chemical Formula 2 below.

[Formula 1]

[Formula 2]

2H ₂ → O ₂ + 4H ⁺ + 4e

The structure of the electrode used in the DC electrolytic bath 151 is the same as the structure of the electrode used in the conventional DC electrolysis, the material of the electrode is titanium platinum is good, the power of 6V to 24V depending on the kind of waste water to be treated It has a free variable power supply (not shown) that can be used selectively.

A typical electrolytic reaction occurring at the anode of the DC electrolytic bath 151 is shown in the following formula (3).

[Formula 3]

2H ₂ O → 4H ⁺ + O ₂ + 4e

In addition, a representative electrolytic reaction occurring at the cathode is shown in the following formula (4).

[Formula 4]

^{_{4H 2 O + 4e → 4OH -}} + 2H 2

Therefore, the electrolytic reaction occurring in the entire DC electrolytic bath 151 may be represented by the following formula (5).

[Formula 5]

^{_{6H 2 O → 4H + + 4OH}} - + 2H 2

Although the above description has been given of the wastewater treatment apparatus including both a DC electrolytic bath and an AC electrolytic bath, it is also possible to include either a DC electrolytic bath or an AC electrolytic bath depending on the composition of the wastewater to be treated.

It will be apparent to those skilled in the art that various changes, modifications, or adjustments may be made to the preferred embodiments described above without departing from the spirit of the invention. Therefore, this invention will include such changes, modifications and adjustments, and the protection scope of this invention will be defined by the claims.

As can be seen from the above description, according to the present invention, not only the power consumption is extremely small by using the low current of the low voltage, but also the life of the electrode is extended to 6,000 to 8,000 hours depending on the material.

In addition, the waste water is removed by floating part by component, and part of the waste water is precipitated and separated after flocculation so that the treated water hardly contains environmental harmful components.

Claims (5)

In the wastewater treatment apparatus for purifying the wastewater by electrolyzing the wastewater by chemical reaction to separate and precipitate the contaminants in the wastewater, An electrolytic unit for electrolyzing the wastewater, a reaction unit for putting various additives into the electrolyzed wastewater and reacting physicochemically, and an agglomeration unit for agglomerating the product by statically maintaining the wastewater after the reaction, The electrolytic unit includes a scraper and an alternating current electrolytic bath for scraping off the injuries floating on the surface in the electrolytic process, The AC electrolytic cell is a wastewater treatment apparatus comprising a pair of main electrodes connected to a power source and a pair of sub-electrodes arranged in parallel with each other at both sides of the pair of main electrodes, respectively. The method of claim 1, The electrolytic unit is a wastewater treatment apparatus comprising a scraper for scraping off the wounds floating on the water surface during the electrolysis process. The method according to claim 1 or 2, And a switch capable of interrupting electrical connection between the power supply and the main electrode and connecting the power supply to the sub-electrode, and a switch capable of cutting off the ground of the sub-electrode. In the wastewater treatment method of purifying the wastewater by electrolyzing and chemically reacting the wastewater by flotation and separation of the contaminants in the wastewater, An electrolytic step of delivering waste water, A reaction step of reacting physicochemically by adding various additives to the electrolyzed wastewater; A flocculation step of aggregating the product by maintaining the waste water after the reaction statically; The electrolysis step is performed by using an AC electrolytic cell including a pair of main electrodes connected to a power source and a pair of sub-electrodes arranged in parallel with each other at both sides of the pair of main electrodes, respectively. Wastewater treatment method. The method of claim 4, wherein The electrolytic step further comprises the step of scraping off the contaminated components on the surface of the waste water treatment method.