Nonlinear current treatment method for ammonia nitrogen electrochemical oxidation of high-salt pharmaceutical wastewater

Abstract

The invention discloses a non-linear current treatment method for ammonia nitrogen electrochemical oxidation of high-salt pharmaceutical wastewater. The non-linear current treatment method comprises the following steps: (1) adding ammonia nitrogen-containing high-salt pharmaceutical wastewater into an electrolytic bath; (2) connecting non-linear current for electrolysis; the nonlinear current is sinusoidal waveform current or chaotic current. According to the method, sinusoidal waveform current or chaotic current has good adaptability to high-salt and high-organic-matter wastewater, the technical problem of concentration polarization of ammonia nitrogen electrochemical oxidation is solved, high nitrogen and nitrogen removal rate is obtained with low electrolysis temperature and current density, treatment of ammonia nitrogen in high-salt pharmaceutical wastewater and energy consumption are achieved, and the method is suitable for industrial production. Wide application prospects are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ammonia-nitrogen wastewater treatment, in particular to a nonlinear current treatment method for electrochemical oxidation of ammonia-nitrogen in high-salt pharmaceutical wastewater. BACKGROUND

[0002] With the continuous development of the industrial field, more and more nitrogen-containing wastewater is discharged into water bodies. Excessive nitrogen in water bodies can cause eutrophication, which in turn affects water quality and aquatic ecology, and can have a serious impact on human life and production. Chemical pharmaceutical wastewater and petrochemical wastewater contain a relatively high concentration of nitrogen, making such wastewater have a relatively low carbon-nitrogen ratio, thereby preventing microorganisms in the water body from utilizing organic carbon sources to degrade nitrogen-containing components in the wastewater as in normal conditions. Microorganisms can only degrade low-concentration nitrogen-containing wastewater, but cannot degrade high-concentration nitrogen-containing wastewater.

[0003] In most cases, pharmaceutical waste salt includes inorganic salt, organic matter and heavy metal. The inorganic matter mainly includes NaCl, Na2SO4, NH4Cl and other inorganic salts, and the organic matter mainly includes methanol, hydroxylamine hydrochloride, etc. Due to the diverse sources of pharmaceutical waste salt, including different enterprises, different products and different production processes, the composition is complex and has high pollution. The nitrogen-containing components in the wastewater before the treatment of pharmaceutical waste salt mainly consist of organic nitrogen and inorganic nitrogen. The organic nitrogen includes urea, amide, etc., and the inorganic nitrogen mainly includes nitrite nitrogen, ammonia nitrogen and nitrate nitrogen, etc. How to efficiently treat nitrogen-containing high-salt pharmaceutical wastewater is one of the main problems faced by the world today. In current water treatment technologies, electrochemical oxidation is a new method. This method relies on strong oxidizing agents generated by electrochemical reactions on the electrode, such as hydroxyl radicals, to complete the purification of water. In the electrochemical treatment process, energy consumption is a core problem. In order to reduce the energy demand of electrochemical treatment, the key is to improve the efficiency of the current and reduce the required voltage. The specific oxidation capacity of the current and the type of organic matter reaction occurring on its surface directly affect the current efficiency, therefore, changing the power supply of the electrolysis process and finding an electrolysis method with adjustable and current continuous variation characteristics are expected to become a new breakthrough for achieving deep purification in the process of ammonia-nitrogen treatment of high-salt pharmaceutical wastewater. SUMMARY

[0004] In view of this, the purpose of the present application is to provide a nonlinear current treatment method for electrochemical oxidation of ammonia-nitrogen in high-salt pharmaceutical wastewater, comprising the following steps:

[0005] (1) adding ammonia-nitrogen-containing high-salt pharmaceutical wastewater into an electrolytic tank;

[0006] (2) connecting a nonlinear current for electrolysis;

[0007] The nonlinear current is a sine wave current or a chaotic current.

[0008] Preferably, the average current density of the nonlinear current is 75-90 A / m 2 .

[0009] Preferably, the average current density of the nonlinear current is 90 A / m 2 .

[0010] Preferably, the temperature of the electrolysis is 20 ℃. The method can be adjusting the water bath temperature of the electrolytic cell to 20 ℃.

[0011] Preferably, the pH value of the high-salt medical wastewater is adjusted to 7.

[0012] Preferably, the anode plate of the cathode and anode plate is a mesh titanium plated with ruthenium iridium, and the cathode plate is stainless steel.

[0013] Preferably, the distance between the cathode and anode plate in the electrolytic cell is 25 mm.

[0014] Preferably, the electrolysis time is 120 minutes.

[0015] Preferably, the frequency of the sinusoidal waveform current is 1000 Hz, and the duty cycle is 50%.

[0016] Preferably, the concentration of ammonium sulfate in the high-salt medical wastewater is 280 mg / L, the concentration of sodium sulfate is 14.2 g / L, and the concentration of chloride ions is 7.5 g / L, and the pH value is adjusted with 1 M NaOH solution.

[0017] The present application provides power by a nonlinear power supply, and the nonlinear current is a sinusoidal waveform current or a chaotic current. Compared with a traditional direct current power supply, the use of a continuously changing nonlinear current for electrochemical oxidation of ammonia nitrogen can reduce the concentration polarization caused by the difference between the ion concentration of the electrode interface layer solution and the bulk solution concentration in the electrolytic cell, and reduce the unit energy consumption. Moreover, the sinusoidal waveform current or the chaotic current of the present method has good adaptability to high-salt high-organic wastewater, solves the technical problem of concentration polarization in electrochemical oxidation of ammonia nitrogen, achieves high nitrogen removal rate at a low electrolysis temperature and current density, realizes the treatment of ammonia nitrogen in high-salt medical wastewater and solves the energy consumption problem, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a circuit structure diagram of the chaotic circuit of the nonlinear chaotic power supply of the present application;

[0019] Figure 2 The figure is an electrolysis device diagram of the nonlinear current electrolysis method for electrochemical oxidation of ammonia nitrogen of the present application (in the figure: power supply 1, current detection meter 2, stainless steel cathode 3, ruthenium iridium titanium base plate 4, organic glass electrolytic cell 5, constant temperature stirring water bath 6);

[0020] Figure 3 Current waveform diagram and experimental parameters of the nonlinear current electrolysis method for electrochemical oxidation of ammonia nitrogen in the present application (wherein (a) current waveform (i on is the on-period pulse current, i off is the off-period pulse current), (b) ammonia nitrogen electrocatalytic effect). DETAILED DESCRIPTION

[0021] The present application will be described in detail below with reference to the examples, which are merely illustrative and not restrictive of the scope of the present application. The present application is not limited to the following embodiments or examples, and any modifications and variations made without departing from the spirit of the present application shall be included within the scope of the present application. The experimental materials and reagents used in the following examples are commercially available unless otherwise specified.

[0022] The current treatment system used in the nonlinear current treatment method for electrochemical oxidation of ammonia nitrogen in high-salinity pharmaceutical wastewater of the present application includes a nonlinear power supply, a cathode, an anode, an electrolytic cell, and a water bath stirring pot.

[0023] The electrolytic cell is internally provided with a magnetic stirrer with a stirring speed of 300 r / min.

[0024] The electrolytic cell is internally provided with anode and cathode plates; the anode plate of the anode and cathode plate is a mesh-shaped titanium plating ruthenium iridium, and the cathode plate is stainless steel; the distance between adjacent anode and cathode plates is 25 mm.

[0025] The two ends of the anode and cathode plate are respectively connected to the cathode and anode of the power supply.

[0026] The nonlinear power supply is a power supply that can output nonlinear waveform current (referred to as "nonlinear current"), which is composed of a nonlinear waveform current signal generator and a power amplifier. According to the different generated current waveforms, the nonlinear power supply is divided into a nonlinear arbitrary wave power supply and a nonlinear chaotic power supply. The nonlinear waveform current signal generator of the nonlinear arbitrary wave power supply is a high-precision high-frequency arbitrary waveform generator (RIGOL, model HU0854), and the waveform characteristics of its output signal include but are not limited to pulse, sine, square wave, and triangular wave; the nonlinear waveform current signal generator of the nonlinear chaotic power supply is a chaotic circuit, which outputs chaotic signals. The output signal of the nonlinear waveform current signal generator is amplified by a power amplifier (Antai Electronics Technology Co., Ltd., model ATA-308) and adjusted to output nonlinear current.

[0027] The following steps are performed using the above system:

[0028] Inject high-salinity pharmaceutical wastewater into the electrolytic cell;

[0029] Start the nonlinear power supply to load nonlinear current for electrolysis.

[0030] The current structure of the chaotic circuit ( Figure 1 The analog multiplier U6 has its VS+ terminal connected to the positive terminal of the DC power supply, and its VS- terminal connected to the negative terminal of the DC power supply. The DC power supply provides a 15V voltage signal to the circuit.

[0031] The Z terminal, X2 terminal, Y1 terminal, and Y2 terminal of the analog multiplier U6 share a common ground.

[0032] The X1 terminal of the analog multiplier U6 receives the signal fed back from the operational amplifier L1;

[0033] The analog multiplier U6 multiplies the received signals to obtain the multiplied signal;

[0034] The W terminal of the analog multiplier U6 transmits the multiplication signal to the negative input terminal of the operational amplifier L1 through resistor R3;

[0035] The negative input terminal of operational amplifier L1 receives the signal fed back from operational amplifier L2 through resistor R1;

[0036] The negative input terminal of operational amplifier L1 receives the signal fed back from operational amplifier L3 through resistor R2;

[0037] The negative input terminal of operational amplifier L1 receives the feedback signal from operational amplifier L4 through resistor R4;

[0038] The positive input terminal of operational amplifier L1 is grounded;

[0039] The output terminal of operational amplifier L1 is connected in series with capacitor C1 and then connected to the negative input terminal of operational amplifier L1.

[0040] The output of operational amplifier L1 is connected in series with resistor R13 and then connected to the negative input of operational amplifier L2.

[0041] The positive input terminal of operational amplifier L2 is grounded;

[0042] The signal output from the output terminal of operational amplifier L2 enters the negative input terminal of operational amplifier L3 through resistor R5;

[0043] The output terminal of operational amplifier L2 is connected to the negative input terminal of operational amplifier L2 after being connected in series with resistor R14.

[0044] The negative input terminal of operational amplifier L3 receives the feedback signal from operational amplifier L3 through resistor R6;

[0045] The positive input terminal of operational amplifier L3 is grounded;

[0046] The output terminal of operational amplifier L3 is connected in series with capacitor C2 and then connected to the negative input terminal of operational amplifier L3.

[0047] The negative input terminal of the operational amplifier L4 receives the signal fed back by the operational amplifier L2 through the resistor R7;

[0048] The positive input terminal of the operational amplifier L4 is grounded;

[0049] The output terminal of the operational amplifier L4 is connected to the negative input terminal of the operational amplifier L4 in series with the capacitor C3;

[0050] The Y1 terminal of the analog multiplier U6 of the chaotic circuit is connected to the power amplifier (U5) Figure 1 (z) of the middle W.

[0051] In the following, the current processing system is used for electrolysis experiments of specific ammonia-nitrogen wastewater:

[0052] Example 1:

[0053] 1) Configure simulated ammonia-nitrogen wastewater: the concentration of ammonium sulfate is 280 mg / L, the concentration of sodium sulfate is 14.2 g / L, and the concentration of chloride ions (ionized from sodium chloride) is 7.5 g / L. The pH value is adjusted to 7 by using 1 M NaOH solution. The nonlinear power supply supplies power to the electrolysis system, and the electrolysis device is as shown in Figure 1 ;

[0054] 2) The nonlinear arbitrary wave power supply outputs a pulse signal current, which is connected to the ammonia-nitrogen electrolysis system. The frequency of the pulse current is 1000 Hz, and the duty cycle is 50%. The distance between the plates in the electrolytic cell is 25 mm, the water bath temperature is 20 ℃, and the average current density is 75 A / m 2 . 150 mL of simulated wastewater in step 1) is measured, and electrolysis is performed for 120 min. The ammonia-nitrogen content in the water sample is detected by using the Nash reagent spectrophotometric method, the ammonia-nitrogen removal rate = (initial ammonia-nitrogen content - ammonia-nitrogen content after electrolysis treatment) / initial ammonia-nitrogen content, and the ammonia-nitrogen removal rate in the simulated ammonia-nitrogen wastewater reaches 67.15%.

[0055] Example 2:

[0056] 1) Configure simulated ammonia-nitrogen wastewater: same as example 1; the nonlinear power supply supplies power to the electrolysis system;

[0057] 2) The nonlinear arbitrary wave power supply outputs a sine signal current, which is connected to the ammonia-nitrogen electrolysis system. The frequency of the sine current is 1000 Hz, and the duty cycle is 50%. The distance between the plates in the electrolytic cell is 25 mm, the water bath temperature is 20 ℃, and the average current density is 75 A / m 2 . 150 mL of simulated wastewater in step 1) is measured, and electrolysis is performed for 120 min. The ammonia-nitrogen removal rate in the simulated ammonia-nitrogen wastewater reaches 76.06%.

[0058] Example 3:

[0059] 1) Configuration of simulated ammonia-nitrogen wastewater: same as Example 1; nonlinear power supply for electrolysis system power supply;

[0060] 2) Nonlinear arbitrary wave power supply output square wave signal current, access square wave current and ammonia-nitrogen electrolysis system; the frequency of the square wave current is 500 Hz, and the duty cycle is 50%. The electrode plate spacing in the electrolytic cell is 25 mm, the water bath temperature is 20 ℃, and the average current density is 75 A / m 2 , 150 mL of simulated wastewater in step 1) is measured, and electrolysis is performed for 120 min. The removal rate of ammonia-nitrogen in simulated ammonia-nitrogen wastewater reaches 61.08%.

[0061] Example 4:

[0062] 1) Configuration of simulated ammonia-nitrogen wastewater: same as Example 1; nonlinear power supply for electrolysis system power supply;

[0063] 2) Nonlinear chaotic power supply outputs chaotic signal current, and accesses chaotic current and ammonia-nitrogen electrolysis system. The electrode plate spacing in the electrolytic cell is 25 mm, the water bath temperature is 20 ℃, and the average current density is 75 A / m 2 , 150 mL of simulated wastewater in step 1) is measured. The removal rate of ammonia-nitrogen in simulated wastewater reaches 88.02%.

[0064] Example 5:

[0065] 1) Configuration of simulated ammonia-nitrogen wastewater: same as Example 1; nonlinear power supply for electrolysis system power supply;

[0066] 2) Change the chaotic current density, and adjust the average current density to 90 A / m 2 . The system is powered by a nonlinear chaotic power supply, and the power supply outputs chaotic current. The electrode plate spacing in the electrolytic cell is 25 mm, the water bath temperature is 20 ℃, 150 mL of simulated wastewater in step 1) is measured, and electrolysis is performed for 120 min. The removal rate of ammonia-nitrogen in simulated wastewater reaches 95.02%.

[0067] In this embodiment, the nonlinear power supply provides electrical energy. Compared with the traditional direct current power supply, the use of nonlinear current with quasi-periodic characteristics and continuous change for electrochemical oxidation of ammonia-nitrogen can reduce the concentration polarization caused by the difference between the electrode interface layer solution ion concentration and the bulk solution concentration, and reduce the unit energy consumption. For ammonia-nitrogen wastewater, using low current density nonlinear current for electrolysis, ammonia-nitrogen can be well removed, and the removal rate can exceed 60%. Among them, the removal rate of sinusoidal current and chaotic current on ammonia-nitrogen has a significant effect, exceeding 75%, especially chaotic current, the removal rate can be as high as more than 88%, and when the average current density of chaotic current is 90 A / m 2The removal rate can reach more than 95%, and the method is energy-saving, environment-friendly and efficient, and has wide application value.

[0068] The conventional techniques and the schemes not described in detail in the above embodiments are well known in the art, and thus will not be described in detail herein. The above embodiments and / or experimental examples describe the preferred embodiments of the present application in detail, however, the present application is not limited to the specific details in the above embodiments, and within the technical concept of the present application, various simple modifications can be made to the technical scheme of the present application, and these simple modifications all belong to the protection scope of the present application.

Claims

1. A nonlinear current treatment method for ammonia nitrogen electrochemical oxidation in high-salinity pharmaceutical wastewater, characterized in that, Includes the following steps: (1) Add high-salt pharmaceutical wastewater containing ammonia nitrogen to the electrolytic cell; (2) Electrolysis is performed by connecting a nonlinear current; The nonlinear current is a sinusoidal current or a chaotic current.

2. The method as described in claim 1, characterized in that, The average current density of the nonlinear current regulation is 75-90 A / m. 2 .

3. The method as described in claim 1, characterized in that, The average current density of the nonlinear current regulation is 90 A / m 2 .

4. The method as described in claim 1, characterized in that, The electrolysis temperature is 20 °C.

5. The method as described in claim 1, characterized in that, The pH value of the high-salt pharmaceutical wastewater was adjusted to 7.

6. The method as described in claim 1, characterized in that, The anode plate of the cathode and cathode plates is made of ruthenium-iridium mesh-plated titanium, and the cathode plate is made of stainless steel.

7. The method as described in claim 1, characterized in that, The distance between the anode and cathode plates in the electrolytic cell is 25 mm.

8. The method as described in claim 1, characterized in that, The electrolysis time is 120 minutes.

9. The method as described in claim 1, characterized in that, The frequency of the sinusoidal current is 1000 Hz and the duty cycle is 50%.

10. The method according to any one of claims 2-9, characterized in that, The high-salt pharmaceutical wastewater contains ammonium sulfate at a concentration of 280 mg / L, sodium sulfate at a concentration of 14.2 g / L, and chloride ion at a concentration of 7.5 g / L, and the pH value is adjusted with 1 M NaOH solution.

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