CN110104758B - A kind of method for advanced treatment of organic matter in high-salt wastewater with electro-cooperative persulfate - Google Patents

Abstract

The invention belongs to the technical field of advanced treatment of industrial waste water, and in particular relates to a method for advanced treatment of organic matter in high-salt waste water by electric synergy with persulfate. The method for advanced treatment of organic matter in high-salt wastewater with electro-cooperative persulfate in the present invention combines the convenience of high-salt wastewater with high salt content and low solution resistance, based on the principle of sulfate radical oxidation, and utilizes direct and indirect oxidation of micro-electric fields. On the basis of direct oxidation and removal of organic matter, persulfate generates more free radicals under the action of micro-electric field to remove organic matter, which can effectively remove refractory organic matter, and can reach more than 90% organic matter removal rate. Solve the problem of difficult deep removal of organic matter in high-salt and high-chlorine wastewater. Compared with the existing conventional persulfate advanced oxidation treatment method, there is no need to add any activator (such as iron), which effectively avoids the secondary pollution caused by the activator, and has the advantage of high efficiency and environmental protection.

Description

A kind of method for advanced treatment of organic matter in high-salt wastewater with electro-cooperative persulfate

technical field

The invention belongs to the technical field of advanced treatment of industrial waste water, and in particular relates to a method for advanced treatment of organic matter in high-salt waste water by electric synergy with persulfate.

Background technique

In recent years, limited by the current level of social and economic development and technological development, many chemical industries inevitably discharge a large amount of high-concentration salt-containing wastewater containing organic pollutants. Most of these pollutants are harmful to the ecological environment and human body, and have already caused Water resources and water environment have caused impact and even harm. Due to the high salt content of such wastewater, it is difficult for conventional microorganisms to survive and grow, making it difficult to treat it by traditional biodegradation methods. Coal chemical industry is a process of converting coal into gas, liquid and solid fuels and other chemicals through chemical conversion. It is a typical high-concentration refractory organic wastewater. There are a lot of carcinogenic and teratogenic toxic and harmful substances such as ammonia nitrogen, phenols, polycyclic aromatic hydrocarbons, etc. in coal chemical wastewater. It has the characteristics of high COD value, high salt content, deep color, and many refractory substances. Organic wastewater with a concentration that is difficult to degrade requires effective treatment before being discharged into natural water bodies.

At present, a series of physical, chemical, biological and their integrated technologies are used to treat coal chemical wastewater, including membrane filtration, biodegradation, chemical oxidation, etc. However, the high salt concentration of coal chemical wastewater limits the biodegradation process, and the high concentration of phenolic compounds contained in it can easily lead to serious membrane fouling, while simple chemical oxidation methods are less effective in treating refractory organics. Therefore, there is a need for a clean, green and efficient method to treat such wastewater.

Advanced Oxidation Process (AOP) is also known as deep oxidation. The strong oxidizing free radicals (such as hydroxyl radical OH) generated in the process can effectively oxidize and degrade the organic substances contained in wastewater. The advantages of complete treatment and wide application range have become the focus of current water treatment technology research. Most of the traditional advanced oxidation technologies use Fenton and Fenton-like reagents and ozone to effectively oxidize and decompose organic compounds with high stability. However, there are still problems in reducing the COD value of industrial waste water with high salt content. It is more difficult, and there is a secondary pollution problem.

The advanced oxidation method of activated persulfate is an emerging salt-containing wastewater treatment technology. The oxidation capacity of the sulfate radical generated by its activation is close to or exceeds the redox potential of the hydroxyl radical (SO ₄ ^- · E ⁰ =2.5-3.1V, The redox potential of OH is E ^{0 =} 1.89-2.72V), and the stability of SO ₄ ^- exceeds that of traditional advanced oxidation _. 1μs)), making it more likely to react with contaminants. Moreover, based on the advanced persulfate oxidation technology, the sulfate radicals generated by activated sodium persulfate are used to oxidize and degrade organic substances, and the product is SO ₄ ^2- , which is not suitable for the high-salt wastewater of coal chemical industry that contains a large amount of Na ₂ SO ₄ and NaCl. It constitutes a new secondary pollution and is an ideal treatment method. Compared with the traditional advanced oxidation technology, activated persulfate oxidation has the advantages of strong oxidizing ability, stable oxidant and wide range of pH adaptation. In addition, persulfate has good water solubility, high stability at room temperature, low price, and mild reaction product. Therefore, advanced oxidation technology based on persulfate has broad prospects in wastewater treatment, especially in advanced treatment of coal chemical wastewater.

There are many means for activation of persulfate in the prior art, typically such as thermal activation, alkali activation, ultraviolet light activation, transition metal activation, and the like. However, alkali activation has the defects of equipment corrosion; ultraviolet light activation has poor treatment effect on coal chemical wastewater with high chroma; transition metal activation has the problems of secondary pollution and self-quenching free radicals.

Because the electrochemical method can make persulfate generate more free radicals under the action of micro-electric field, it can act on the oxidation and removal of organic matter, and can realize direct or indirect oxidation on the surface of the electrode. Therefore, the electrochemical method is combined with the persulfate method. It can improve the oxidation efficiency to a certain extent and become the preferred process for the treatment of organic matter in industrial wastewater. However, most of the current electrochemical synergistic persulfate technology needs to use iron or ferrous ions as activators, and iron sludge is inevitably produced as a by-product during the treatment process, which will cause certain secondary pollution. It can be seen that the traditional electro-cooperative persulfate advanced oxidation technology still has certain limitations for the advanced treatment of organic matter in high-salt wastewater due to the existence of activators.

SUMMARY OF THE INVENTION

For this reason, the technical problem to be solved by the present invention is to provide a method for advanced treatment of organic matter in high-salt wastewater with electric synergistic persulfate, so as to solve the problem of secondary pollution in the prior art with synergistic persulfate advanced oxidation.

In order to solve the above-mentioned technical problems, a method for the advanced treatment of organic matter in high-salt wastewater with electro-synergy persulfate according to the present invention, comprises the following steps:

(1) add persulfate oxidant to the high-salt wastewater to be treated, fully mix, and adjust the pH value of the high-salt wastewater to be greater than 11;

(2) Inserting an electrode into the high-salt wastewater, and applying a voltage to react to complete the degradation of organic matter in the wastewater.

Specifically, in the step (1), the persulfate oxidizing agent includes sodium persulfate and/or potassium persulfate.

Specifically, in the step (1), the added amount of the persulfate oxidant is 1-10 g/L waste water.

Specifically, in the step (1), the pH value of the high-salt wastewater is adjusted to 11.5-12.5.

The pH value can be adjusted using H ₂ SO ₄ or NaOH according to the pH value of the initial wastewater.

Specifically, in the step (1), in the high-salt wastewater to be treated, the initial concentration of organic matter is 50-200 mg/L, the chloride ion concentration is 7500-15000 mg/L, and the TDS range is 23000-45000 mg/L.

Specifically, in the step (2), the electrode is a carbon plate electrode.

Specifically, the size of the electrodes is 4-6 cm×2-3 cm, and the distance between the electrodes is controlled to be 3-7 cm.

Specifically, in the step (2), the applied voltage of the electrodes is controlled to be 2-2.5V.

Specifically, in the step (2), the reaction time is 3-6h.

The invention also discloses the application of the method for the advanced treatment of organic matter in high-salt wastewater by electric synergy with persulfate in the field of advanced treatment of organic matter in high-salt wastewater.

According to the method for advanced treatment of organic substances in high-salt wastewater by electrolysis with persulfate in the present invention, it is surprisingly found in a large number of experimental studies that the salt substances existing in the wastewater are mainly NaCl and Na ₂ SO ₄ , and NaCl is used as electrolyte and is Oxidative HClO can be generated during the chemical process, which is beneficial to electrochemical oxidation. Therefore, the method of the present invention for the advanced treatment of organic matter in high-salt wastewater with electric synergistic persulfate, combined with the convenience of high salt content and low solution resistance of high-salt wastewater, is based on the principle of sulfate radical oxidation, and utilizes the direct and Indirect oxidation, based on the electric synergy of Na ₂ S ₂ O ₈ to generate strong oxidizing free radical SO ₄ ^- ·, on the basis of direct oxidation to remove organic matter, makes persulfate generate more free radicals under the action of micro electric field. removal of organic matter. On this basis, the deep removal effect can be enhanced by a simple process of adjusting pH to alkaline, which can overcome and make full use of the high-salt environment of high-salt wastewater, not be affected by a large number of inorganic ions in the wastewater, and can effectively remove refractory organic matter, which can reach 90 The removal rate of organic matter is more than %, the effect is remarkable, it is a very appropriate way of energy saving and emission reduction, especially suitable for salty wastewater system, which can solve the problem of difficult deep removal of organic matter in high-salt and high-chlorine wastewater. Compared with the existing conventional persulfate advanced oxidation treatment method, there is no need to add any activator (such as iron), which not only omits the activation step to make the process simpler, but also effectively avoids the secondary pollution caused by the activator, and has high efficiency. Environmental advantages.

The method for advanced treatment of organic matter in high-salt wastewater by electro-cooperative persulfate in the present invention uses sodium persulfate as the oxidant, which not only has good water solubility, stable storage, and low price, but also the by-product after the reaction is Na ₂ SO ₄ , which is free of The introduction of secondary pollution can be followed by evaporation and recovery of salt production.

Detailed ways

In the following embodiments of the present invention, the wastewater to be treated is the high-salt wastewater containing the typical organic 2-methoxyphenol configured with reference to the high-salt coal chemical wastewater of a large-scale coal chemical enterprise, wherein the organic pollutant 2-methoxyphenol The initial concentration of 50-200mg/L.

The detection of the content of 2-methoxyphenol in the following embodiments of the present invention adopts the conventional liquid chromatography method of the prior art, and specifically includes:

The mobile phase is methanol-water (50:50) mixed solution, and the flow rate is 1 mL/min;

UV detector, detection wavelength 270nm.

All samples were filtered through a 0.45 μm filter before injection.

Taking the degradation rate of 2-methoxyphenol as the analysis index, the calculation formula is as follows:

式中，

In the formula,

C ₀ is the initial concentration of 2-methoxyphenol, mg/L;

C _t is the concentration of 2-methoxyphenol at the end of the reaction, mg/L.

Example 1

The method for the advanced treatment of organic matter in high-salt wastewater by electricity with persulfate in the present embodiment includes the following steps

(1) get 300mL waste water (TDS value sees following table 1) that 2-methoxyphenol concentration is 50mg/L in reactor, add 0.3g sodium persulfate, make the sodium persulfate concentration in solution be 1g/L ( At this time, the solution is neutral, with a pH of about 7), and the initial pH of the wastewater is adjusted to 12 with NaOH;

(2) Insert a pair of carbon plate electrodes (5 × 2.5cm) into the reactor, keep the distance between the plates at 3cm, supply power with a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 3h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Example 2

The method for the advanced treatment of organic matter in high-salt wastewater by electricity with persulfate in the present embodiment includes the following steps

(1) get 2-methoxyphenol concentration and be 300mL waste water (TDS value is shown in table 1 below) of 100mg/L in the reactor, add 0.9g sodium persulfate, make the sodium persulfate concentration be 3g/L in the solution, And adjust the initial pH of wastewater to 12;

(2) Insert a pair of carbon plate electrodes (5 × 2.5cm) into the reactor, keep the distance between the plates at 3cm, supply power with a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 3h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Example 3

The method for the advanced treatment of organic matter in high-salt wastewater by electricity with persulfate in the present embodiment includes the following steps

(1) get 300mL waste water (TDS value is shown in table 1 below) that 2-methoxyphenol concentration is 200mg/L in reactor, add 1.5g sodium persulfate, make the sodium persulfate concentration be 5g/L in the solution, And adjust the initial pH of wastewater to 12;

(2) Insert a pair of carbon plate electrodes (5 × 2.5cm) into the reactor, keep the distance between the plates at 3cm, supply power with a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 3h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Example 4

The method for the advanced treatment of organic matter in high-salt wastewater by electricity with persulfate in the present embodiment includes the following steps

(1) get 300mL waste water that 2-methoxyphenol concentration is 200mg/L, TDS value is 23000mg/L in reactor, add 1.5g sodium persulfate, make the sodium persulfate concentration in solution be 5g/L, and Adjust the initial pH of wastewater to 12;

(2) Insert a pair of carbon plate electrodes (5 × 2.5cm) into the reactor, keep the distance between the plates at 3cm, supply power with a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 3h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Example 5

The method for the advanced treatment of organic matter in high-salt wastewater by electricity with persulfate in the present embodiment includes the following steps

(1) get 300mL waste water that 2-methoxyphenol concentration is 200mg/L, TDS value is 23000mg/L in reactor, add 3g sodium persulfate, make the sodium persulfate concentration in solution be 10g/L, and adjust The initial pH of the wastewater is 12;

(2) Insert a pair of carbon plate electrodes (5 × 2.5cm) into the reactor, keep the distance between the plates at 3cm, supply power with a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 3h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Example 6

The method for the advanced treatment of organic matter in high-salt wastewater by electricity with persulfate in the present embodiment includes the following steps

(1) get 300mL waste water (TDS value is shown in table 1 below) that 2-methoxyphenol concentration is 200mg/L in reactor, add 1.5g sodium persulfate, make the sodium persulfate concentration be 5g/L in the solution, And adjust the initial pH of wastewater to 11.5;

(2) Insert a pair of carbon plate electrodes (5×2.5cm) into the reactor, keep the distance between the plates at 5cm, supply power with a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 6h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Example 7

The method for advanced treatment of organic matter in high-salt wastewater by electro-cooperative persulfate in this embodiment includes the following steps

(1) get 300mL waste water (TDS value is shown in table 1 below) that 2-methoxyphenol concentration is 200mg/L in reactor, add 1.5g sodium persulfate, make the sodium persulfate concentration be 5g/L in the solution, And adjust the initial pH of wastewater to 12.5;

(2) Insert a pair of carbon plate electrodes (5 × 2.5cm) into the reactor, keep the distance between the plates at 7cm, supply power from a constant voltage power supply, set the voltage to 2V, start the sulfate radical oxidation reaction, and the reaction time is 5h .

After the reaction is completed, the power is turned off and the electrode is taken out to terminate the reaction, and the solution in the reactor is the reaction effluent.

Comparative Example 1

The method for treating organic matter in high-salt wastewater described in this comparative example is the same as that in Example 3, the only difference being that, during the degradation process, no micro-electric field is applied, that is, no electrode plate is inserted.

Comparative Example 2

The method for treating organic matter in high-salt wastewater described in this comparative example is the same as that in Example 3, except that in the degradation process, no persulfate oxidant is added, and only electrode electrification is performed.

Get the reaction effluent after treatment in above-mentioned embodiment 1-5 and comparative example 1-2, adopt above-mentioned high performance liquid chromatography method to carry out the determination of remaining organic matter content, and use TDS detection pen to measure TDS, record result is shown in table 1 below.

Table 1 Remaining organic matter concentration in reaction effluent and TDS measurement results

As can be seen from the data in the above table, the method for the advanced treatment of organic matter in high-salt wastewater by electro-cooperative persulfate according to the present invention is based on the combination of electrochemical method and persulfate advanced oxidation, and can be used without adding any activator. To achieve the deep removal of organic matter in high-chlorine and high-salt wastewater, compared with the single treatment method that does not use electric synergy or does not add persulfate, it can achieve better removal of organic matter (greater than 90%, increased by more than 75% and 33%, respectively. %), the removal efficiency can reach the level of adding Fe ²⁺ for activation in the prior art, and at the same time, the secondary pollution caused by the activator is effectively avoided. Therefore, the method for advanced treatment of organic matter in high-salt wastewater by electro-cooperative persulfate in the present invention has a wide range of application and broad application prospects for treating organic matter in high-chlorine and high-salt coal chemical wastewater.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (4)

1. The method for deeply treating the organic matters in the high-salinity wastewater by using the electricity in cooperation with the persulfate is characterized by fully utilizing the high-salinity environment of the high-salinity wastewater without adding any activating agent, and comprises the following steps of:

(1) adding persulfate oxidant into the high-salinity wastewater to be treated, fully and uniformly mixing, and adjusting the pH value of the high-salinity wastewater to be 11.5-12.5;

controlling the initial concentration of organic matters in the high-salinity wastewater to be treated to be 50-200mg/L, the concentration of chloride ions to be 7500-15000mg/L and the TDS range to be 23000-45000 mg/L;

(2) inserting a pair of carbon plate electrodes into the high-salinity wastewater, controlling the size of the electrodes to be 4-6cm multiplied by 2-3cm, controlling the distance between the electrodes to be 3-7cm, applying 2-2.5V voltage by a constant voltage power supply to react, and finishing the degradation of organic matters in the wastewater.

2. The method for deeply treating organic matters in high-salinity wastewater by using the electrically synergistic persulfate as claimed in claim 1, wherein, in the step (1), the persulfate oxidant comprises sodium persulfate and/or potassium persulfate.

3. The method for deeply treating the organic matters in the high-salinity wastewater by using the electrically synergistic persulfate according to the claim 1 or the claim 2, wherein in the step (1), the addition amount of the persulfate oxidizer is 1 to 10g/L of wastewater.

4. The method for deeply treating the organic matters in the high-salinity wastewater by using the electrically synergistic persulfate as claimed in the claim 1 or the claim 2, wherein the reaction time in the step (2) is 3 to 6 hours.