CN1412124A - Treatment method of waste water and its equipment - Google Patents

Abstract

The invention relates to a waste water treatment method, comprising the following steps: putting waste water and iron salt reagents into an electrolysis/oxidation tank; adjusting the pH value to below 2.5, carrying out electrolytic oxidation reaction and continuously adding hydrogen peroxide. The present invention also provides a wastewater treatment device, comprising an electrolysis/oxidation tank, the anode of the electrolysis/oxidation tank is a flat insoluble anode; A device for adding hydrogen peroxide. The invention utilizes the flat plate reflux electrolysis method to increase the reaction rate of ferric iron at the cathode, thereby improving the electrochemical reduction efficiency, and continuously adds hydrogen peroxide during the reaction process, so that it can continuously react with the reduced ferrous iron to form Ferric iron, so that the ratio of ferric iron to ferrous iron in the solution can always be maintained at a high value, so even at a lower ferric iron concentration (1000mg/L) and a higher pH value (pH<2.5 ), still maintaining high processing efficiency. Compared with the conventional improved Fenton method, high current efficiency needs to be obtained at a higher ferric iron concentration (30,000 mg/L) and a lower pH value (pH<1), and the present invention is more economical.

Description

A kind of wastewater treatment method and equipment

technical field

The present invention relates to a wastewater treatment method and equipment, in particular to an electrolysis/oxidation wastewater treatment method that utilizes flat plate reflux electrolysis to improve electrochemical reduction efficiency, and is especially suitable for high-concentration COD (chemical oxygen demand) organic wastewater treatment.

Background technique

The treatment principle of traditional equipment is to use hydrogen peroxide and ferrous ions to react to produce hydroxyl radicals (OH) with high oxidation ability to oxidize organic matter in wastewater (ie Fenton method), so as to reduce COD and improve water quality. One of the more feasible methods, but this method still has the following disadvantages in practical application:

1. High operating costs: Adding excessive hydrogen peroxide, ferrous ions, acids, alkalis and other chemicals to the wastewater makes the operating costs high, and the cost of adding ferrous ions and subsequent sludge treatment accounts for about 1/4~ 1/2.

2. High sludge yield: Since ferrous ions must be added during the reaction, iron hydroxide (Fe(OH) ₃ ) sludge will be produced at the end of the reaction. In addition to the further treatment and disposal of these sludges, And will cause secondary pollution.

Contents of the invention

The present invention provides a treatment method and equipment for removing high-concentration COD waste water in order to solve the above problems. The oxidation reaction of organic pollutants is carried out in the same reaction tank, and the ferric iron sludge produced by the Fenton method can be reduced at the same time. It can be used to reduce sludge production and improve its electrolytic reduction efficiency, thereby achieving the purpose of reducing operating costs and promoting the removal efficiency of organic pollutants.

The technical solution provided by the invention is a method for treating waste water, comprising the following steps:

(a) waste water and iron salt reagent are placed in an electrolysis/oxidation tank;

(b) If the pH of the wastewater is > 2.5, after adding the iron salt reagent, adjust the pH value to below 2.5, and carry out electrolytic oxidation

React and continue to add hydrogen peroxide; if the pH of the wastewater is less than 2.5, then directly carry out electrolysis of oxygen after adding the iron salt reagent

Chemical reaction and continuous addition of hydrogen peroxide.

The addition amount of the above-mentioned iron salt reagent is 500-5000 mg per liter of waste water.

The above electrolytic oxidation reaction is carried out at a pH value between 1.5 and 2.5.

The above-mentioned iron salt reagent can be divalent iron or trivalent iron reagent.

The above-mentioned iron salt reagent is an aqueous solution of ferrous sulfate, ferrous chloride, ferric sulfate or ferric chloride.

The present invention also provides a wastewater treatment device, comprising an electrolysis/oxidation tank, the anode of the electrolysis/oxidation tank is a flat insoluble anode; A device for adding hydrogen peroxide.

The above-mentioned device for injecting hydrogen peroxide is a hydrogen peroxide storage tank and a quantitative pump for introducing the hydrogen peroxide in the hydrogen peroxide storage tank into the electrolysis/oxidation tank.

The invention utilizes the flat plate reflux electrolysis method to increase the reaction rate of ferric iron at the cathode, thereby improving the electrochemical reduction efficiency, and continuously adds hydrogen peroxide during the reaction process, so that it can continuously react with the reduced ferrous iron to form Ferric iron, so that the ratio of ferric iron to ferrous iron in the solution can always be maintained at a high value, so even at a lower ferric iron concentration (1000mg/L) and a higher pH value (pH<2.5 ), still maintaining high processing efficiency. Compared with the conventional improved Fenton method, high current efficiency needs to be obtained at a higher ferric iron concentration (30,000 mg/L) and a lower pH value (pH<1), and the present invention is more economical.

Description of drawings

The accompanying drawing is a structural schematic diagram of the wastewater treatment device of the present invention.

Detailed ways

Referring to accompanying drawing, the utility model comprises electrolysis/oxidation tank 1, and the anode 3 of electrolysis/oxidation tank 1 is flat plate insoluble anode; And the storage tank 7 that injects hydrogen peroxide and the quantitative pump 6 that introduces the hydrogen peroxide in the hydrogen peroxide storage tank 7 into the electrolysis/oxidation tank.

The treatment process of the equipment of the present invention is carried out in the electrolysis/oxidation tank 1. The material of the electrolysis/oxidation tank 1 can be non-metallic, such as PP or PE plastics, or metal, such as stainless steel or iron alloy. constituted. The anode 3 of the electrolysis/oxidation tank is, for example, a flat insoluble anode; and its cathode 4, for example, can be formed by connecting a cathode rod to a flat metal cathode to cooperate with a non-metallic electrolysis/oxidation tank; if the electrolysis/oxidation tank body Since it is made of metal, the flat metal cathode can be directly connected to the electrolysis/oxidation tank without a cathode rod. The number of cathodes and anodes can be adjusted according to the water quality, and is not limited to the number shown in the attached drawing. According to the equipment of the present invention, waste water and iron salt reagents are first placed in the electrolysis/oxidation tank 1 . The above-mentioned iron salt reagent can be a ferrous or ferric reagent, such as an aqueous solution of ferrous sulfate, ferrous chloride, ferric sulfate or ferric chloride.

Start the reflux pump 2 to make the passing waste water flow back to the electrolysis/oxidation tank 1, and control the appropriate flow rate. Then, adjust the pH value of the wastewater to below 2.5 (if the pH value of the wastewater is already less than 2.5, there is no need to adjust the pH value again), and prepare for the electrolysis/oxidation reaction.

Next, turn on the power supply 5 and set the cathode current density at 10-100A/m ² , and at the same time continuously add 5000-50000 mg/liter of waste water·hour of hydrogen peroxide for the reaction to proceed.

According to the present invention, when the range of iron salt concentration is above 1000 mg/L and applied to high-concentration organic wastewater, the removal rate of COD can be as high as 85%-98%, or even higher.

The application field of the present invention is quite extensive, comprises:

(1) Treatment of waste liquid containing chemical copper and chemical nickel in electroplating industry, PCB industry and metal surface treatment industry.

(2) Treatment of high-concentration COD waste liquid in the chemical industry, man-made fiber textile industry, and paper industry.

(3) Treatment of high-concentration organic waste liquid in the laboratory.

The present invention will be further described below through examples and comparative examples.

Comparative example: In this comparative example, 1,000mg/L of iron ion concentration and the Fenton method of quantitative injection of 7.7g/hr hydrogen peroxide are used to treat aniline-containing waste liquid. Aniline can be decomposed by 98% after 4 hours, but in terms of COD removal It has no effect, but the COD rises due to the residual oxidation intermediates of aniline and hydrogen peroxide. The detailed operating conditions and processing results are as follows:

1. Operating conditions:

Anode: Titanium-based DSA flat plate electrode

Cathode: SUS304 stainless steel plate electrode

Tank specification: 16cm(L)×15cm(W)×22cm(H)

Waste water volume: 4.0L

Total iron concentration: 1000mg/L

Stirring method: pump suction and reflux stirring

H2O2 feed flow rate: 0.9mL/min

Power supply mode: DC: 0A

Current density: cathode 0A/m ² , anode 0A/m ²

2. Experimental results: Response time (hr) pH Current (A) Aniline×10 ^-2 (mole/L) Aniline removal rate (%) COD (mg/L) COD removal rate (%) 0 2.0 0.0 1.0 0 2540 0 1 2.0 0.0 0.7 30 2339 7.9 2 2.0 0.0 0.48 52 2410 5.1 3 2.0 0.0 0.1 90 2870 -13 4 2.0 0.0 0.04 96 3048 -20

Embodiment: In this embodiment, under the same situation as the comparative example under other conditions, only the electrolysis reaction is increased, and the COD removal rate of 80.2% is arranged after 3 hours of reaction. The method of oxidation reaction and the continuous addition of hydrogen peroxide can indeed keep the reaction at a high current efficiency and improve the removal efficiency of organic pollutants. The detailed operating conditions and processing results are as follows:

1. Operating conditions:

Anode: Titanium-based DSA flat plate electrode

Cathode: SUS304 stainless steel plate electrode

Tank specification: 16cm(L)×15cm(W)×22cm(H)

Waste water volume: 4.0L

Total iron concentration: 1000mg/L

Stirring method: pump suction and reflux stirring

H2O2 feed flow rate: 0.9mL/min

Power supply mode: DC: 8A

Current density: cathode 66.7A/m ² , anode 66.7A/m ²

2. Experimental results: Response time (hr) pH Current (A) Aniline×10 ^-2 (mole/L) Aniline removal rate (%) COD (mg/L) COD removal rate (%) 0 2.30 8.0 1.0 0 2540 0 1 2.08 8.0 0.21 79 1981 22.0 2 2.09 8.0 0.02 98 993 68.1 3 2.11 8.0 0 100 503 80.2 4 2.14 8.0 0 100 236 90.7

Claims (7)

1. A treatment method for waste water, comprising the following steps: (a) waste water and iron salt reagent are placed in an electrolysis/oxidation tank; (b) If the pH of the wastewater is > 2.5, after adding the iron salt reagent, adjust the pH value to below 2.5, and carry out electrolysis of oxygen Hydrogen peroxide reaction and continuous addition of hydrogen peroxide; if the pH of the wastewater is <2.5, the electrolysis is carried out directly after adding the iron salt reagent Decompose the oxidation reaction and continuously add hydrogen peroxide. 2. The method according to claim 1, characterized in that: the amount of the iron salt reagent added is 500-5000 mg per liter of waste water. 3. The method according to claim 1 or 2, characterized in that: the electrolytic oxidation reaction is carried out at a pH value between 1.5 and 2.5. 4. The method according to claim 3, characterized in that: the above-mentioned iron salt reagent can be ferrous or ferric. 5. The method according to claim 4, characterized in that: the above-mentioned iron salt reagent is an aqueous solution of ferrous sulfate, ferrous chloride, ferric sulfate or ferric chloride. 6. A kind of waste water treatment equipment, it is characterized in that: comprise electrolysis/oxidation tank, the anode of electrolysis/oxidation tank is flat plate insoluble anode; Negative electrode is flat metal cathode, is provided with the reflux pump that makes the waste water in electrolysis/oxidation tank reflux and A device for injecting hydrogen peroxide. 7. The device according to claim 6, characterized in that: the device for injecting hydrogen peroxide is a hydrogen peroxide storage tank and a quantitative pump for introducing the hydrogen peroxide in the hydrogen peroxide storage tank into the electrolysis/oxidation tank.

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