A sodium acetate carbon source water treatment agent for sewage treatment and its preparation method

Abstract

The present invention relates to the technical field of water treatment, and discloses a sodium acetate carbon source water treatment agent for sewage treatment and a preparation method thereof. The sodium acetate carbon source water treatment agent comprises the following raw materials in parts by weight: 65-75 parts of sodium acetate, 7-12 parts of polybutylene succinate, 3-4 parts of low-temperature activator, 0.5-1 part of microbial activator, 8-13 parts of heavy metal adsorbent, and 0.5-1 part of COD degrader. The present invention selects sodium acetate as the main carbon source, which can provide easily degradable organic carbon and quickly activate denitrifying bacteria. The addition of a low-temperature activator ensures the stability of the sodium acetate carbon source water treatment agent at low temperatures and improves the low-temperature self-adaptability. At a water temperature of 5°C, a relatively high COD removal rate and heavy metal removal rate are still retained, meeting the requirements for use at low temperatures.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and more specifically, to a sodium acetate carbon source water treatment agent for sewage treatment and a preparation method thereof. Background Art

[0002] In the process of sewage treatment, sewage treatment agents with various functions are used, and the carbon source is one of them. The carbon source can not only promote the growth and reproduction of microorganisms, but also provide the carbon element required for denitrifying bacteria to carry out denitrification and nitrogen removal, thereby accelerating the process of removing pollutants by microorganisms.

[0003] Sodium acetate, also known as sodium acetate, is a water-soluble salt that can quickly dissolve in water and release acetate ions, providing a rapidly available carbon source for microorganisms. It has good biodegradability. Moreover, sodium acetate can be effectively degraded by a variety of microorganisms, especially in anaerobic digestion and aerobic reactions during sewage treatment, serving as a carbon source to support the growth and reproduction of microorganisms and promoting the removal of organic matter. In some wastewater treatment processes (such as anaerobic ammonium oxidation), adding sodium acetate can improve the removal efficiency of nitrogen and phosphorus. By providing an additional carbon source, it can help form a more favorable microbial community and enhance the removal effect of N and P. However, the role of sodium acetate mainly focuses on the denitrification function, lacking the ability to co-treat heavy metals (such as Pb 2+ , Cr(VI)) and refractory COD. And due to the single function of sodium acetate, it cannot meet the treatment requirements of complex scenarios such as alpine regions and industrial wastewater. Therefore, constructing a multi-functional - low-temperature adaptive - high-stability carbon source system is an urgent problem for those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention proposes a sodium acetate carbon source water treatment agent for sewage treatment and a preparation method thereof, aiming to solve the problem of the single function of sodium acetate when used as a carbon source in the current technology.

[0005] On the one hand, the present invention provides a sodium acetate carbon source water treatment agent for sewage treatment, comprising the following raw materials in parts by weight:

[0006] 65 - 75 parts of sodium acetate, 7 - 12 parts of polybutylene succinate, 3 - 4 parts of low-temperature activator, 0.5 - 1 part of microbial activator, 8 - 13 parts of heavy metal adsorbent, 0.5 - 1 part of COD degrader.

[0007] Preferably, the sodium acetate carbon source water treatment agent for sewage treatment comprises the following raw materials in parts by weight:

[0008] 68 - 72 parts of sodium acetate, 9 - 11 parts of polybutylene succinate, 3 - 4 parts of low - temperature activator, 0.5 - 1 part of microbial activator, 9 - 11 parts of heavy - metal adsorbent, 0.5 - 1 part of COD degrader.

[0009] Preferably, the particle size of the polybutylene succinate is 50 - 100 μm;

[0010] The low - temperature activator includes one or more of potassium formate, betaine, and potassium thiocyanate;

[0011] The microbial activator includes: picolinic acid.

[0012] Preferably, the heavy - metal adsorbent includes sulfur - doped mesoporous biochar and chlorine - intercalated magnesium - aluminum layered double hydroxide;

[0013] The specific surface area of the sulfur - doped mesoporous biochar is 1250 ± 50 m 2 / g, and in the sulfur - doped mesoporous biochar, the mass content of sulfur is 10 - 12%;

[0014] The mass ratio of the sulfur - doped mesoporous biochar to the chlorine - intercalated magnesium - aluminum layered double hydroxide is (5 - 8):(3 - 5).

[0015] Preferably, the preparation method of the sulfur - doped mesoporous biochar includes the following preparation steps:

[0016] After grinding rice husks, soak them in a hydrochloric acid solution to obtain pretreated rice husk powder;

[0017] Under a nitrogen atmosphere, mix the pretreated rice husk powder with potassium hydroxide and carbonize to obtain carbonized rice husk powder;

[0018] Sulfurize under a sulfur - containing mixed gas to obtain the sulfur - doped mesoporous biochar;

[0019] The concentration of the hydrochloric acid solution is 0.1 - 0.2 mol / L, and the soaking time is 1 - 2 h;

[0020] The mass ratio of the pretreated rice husk powder to potassium hydroxide is 1:(2 - 4), the carbonization temperature is 750 - 850 °C, and the carbonization time is 1 - 2 h;

[0021] The sulfur - containing mixed gas includes hydrogen sulfide and nitrogen, the volume ratio of hydrogen sulfide to nitrogen is 1:(3 - 4), the sulfuration temperature is 600 - 650 °C, and the sulfuration time is 1 - 2 h.

[0022] Preferably, the preparation method of the chlorine - intercalated magnesium - aluminum layered double hydroxide includes the following steps:

[0023] After mixing and stirring magnesium nitrate, aluminum nitrate, and water, add a sodium hydroxide salt solution, carry out a hydrothermal reaction, and filter;

[0024] Immerse the filter residue in a hydrochloric acid solution and dry it to obtain the chlorine-intercalated magnesium-aluminum layered double hydroxide;

[0025] In the sodium hydroxide salt solution, the molar ratio of sodium hydroxide to sodium chloride is 0.4:(0.1 - 0.2);

[0026] The molar ratio of magnesium nitrate, aluminum nitrate to sodium hydroxide is (0.2 - 0.3):0.1:0.4;

[0027] The temperature of the hydrothermal reaction is 55 - 65 °C, and the time of the hydrothermal reaction is 10 - 12 h;

[0028] The concentration of the hydrochloric acid solution is 0.1 - 0.2 mol / L, and the impregnation time is 20 - 40 min.

[0029] Preferably, the COD degrading agent includes nano-zero-valent iron@biochar;

[0030] The nano-zero-valent iron@biochar is a nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material.

[0031] Preferably, the preparation method of the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material includes the following steps:

[0032] Place the sulfur-doped mesoporous biochar in a ferric chloride solution and sonicate to obtain a mixed solution;

[0033] Carry out a supercritical reduction reaction on the mixed solution, and then passivate and dry it to obtain the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar;

[0034] The mass-volume ratio of the sulfur-doped mesoporous biochar to the ferric chloride solution is 1 g:(15 - 25 mL), the concentration of the ferric chloride solution is 0.3 - 0.6 mol / L, and the sonication time is 20 - 40 min;

[0035] The pressure of the supercritical reduction reaction is 20 - 25 MPa, and the time of the supercritical reduction reaction is 1 - 2 h;

[0036] The passivation process includes: washing the product obtained from the supercritical reduction reaction with an ethanol solution of polyvinylpyrrolidone, and the mass concentration of the ethanol solution of polyvinylpyrrolidone is 0.1% - 0.2%.

[0037] On the other hand, the present invention also provides a preparation method of the sodium acetate carbon source water treatment agent for sewage treatment described above, including the following preparation steps:

[0038] (1) Mix polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide, and a low-temperature activator to obtain a first mixture. Spray a binder on the surface of the first mixture to obtain core particles;

[0039] (2) Mix nano-zero-valent iron supported sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture. Use the electrostatic spraying method to coat the second mixture on the surface of the core particles to form a 50 - 80 μm functional layer;

[0040] (3) Mix sodium acetate with a low-temperature activator to obtain a third mixture. Through centrifugal spray drying, coat the third mixture on the surface of the functional layer to obtain treatment agent particles;

[0041] (4) Immerse the treatment agent particles in a glutaraldehyde solution for cross-linking reaction. After the cross-linking reaction ends, dry to obtain the sodium acetate carbon source water treatment agent.

[0042] Preferably, in step (1), the binder is a hydroxypropyl methylcellulose ethanol solution, and the mass concentration of the hydroxypropyl methylcellulose ethanol solution is 3% - 6%;

[0043] The temperature of the spraying is -20~-15°C;

[0044] In step (2), the voltage of the electrostatic spraying method is 20 - 25 kV, and the flow rate of the electrostatic spraying method is 1 - 2 mL / min;

[0045] In step (3), the inlet temperature of the centrifugal spray drying is 30 - 40°C, and the outlet temperature of the centrifugal spray drying is 5 - 8°C; the mass ratio of the low-temperature activator in step (1) to the low-temperature activator in step (3) is (1 - 2):1;

[0046] In step (4), the mass concentration of the glutaraldehyde solution is 0.3% - 0.6%, the pH is 8 - 8.5, and the time of the cross-linking reaction is 8 - 12 s.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The present invention provides a sodium acetate carbon source water treatment agent for sewage treatment, which comprises raw materials in the following parts by weight: 65-75 parts of sodium acetate, 7-12 parts of polybutylene succinate, 3-4 parts of low-temperature activator, 0.5-1 part of microbial activator, 8-13 parts of heavy metal adsorbent, and 0.5-1 part of COD degrader. The present invention selects sodium acetate as the main carbon source, which can provide easily degradable organic carbon and quickly activate denitrifying bacteria. Moreover, sodium acetate hydrolyzes to generate acetic acid, maintaining the weakly alkaline environment required for denitrification. Polybutylene succinate has the effect of slow-release carbon source, and continuously releases succinic acid (C4H6O4) through the hydrolysis of ester bonds, avoiding the excessive proliferation of bacteria caused by instantaneous overdose of carbon source. At the same time, the degradation product succinic acid can be used as an electron shuttle to improve the denitrification electron transfer efficiency. The low-temperature activator ensures that the sodium acetate carbon source water treatment agent remains liquid at -20°C, improving the low-temperature self-adaptability.

[0049] 2. The present invention further defines that the microbial activator includes picolinic acid, which can induce the expression of nirS and nosZ genes of denitrifying bacteria, improving the activity of nitrate reductase (NAR); at the same time, it can form a stable complex with Cu 2+ / Zn 2+ to reduce the biological toxicity of heavy metals.

[0050] 3. The present invention further defines that the heavy metal adsorbent includes sulfur-doped mesoporous biochar and chlorine-intercalated magnesium-aluminum layered double hydroxide. The -SH groups on the surface of sulfur-doped mesoporous biochar can specifically bind to Pb 2+ / Cd 2+ to improve the adsorption capacity of the sodium acetate carbon source water treatment agent for heavy metals. The Cl ⁻ in chlorine-intercalated magnesium-aluminum layered double hydroxide exchanges with CrO4²⁻ to improve the removal capacity of Cr(VI), and at the same time can release OH⁻ to maintain the pH between 7 and 8, optimizing the conditions for denitrification and heavy metal precipitation.

[0051] 4. The present invention further defines that the COD degrader includes nano-zero-valent iron@biochar. Zero-valent iron can promote the Fenton-like reaction, releasing electrons through Fe 0 →Fe² + to generate -OH radicals (Fenton-like reaction) to degrade refractory organic matter (such as benzene series).

[0052] 5. The present invention also provides a preparation method of the sodium acetate carbon source water treatment agent for sewage treatment, which comprises the following preparation steps: (1) Mix polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide and a low-temperature activator to obtain a first mixture, and spray a binder on the surface of the first mixture to obtain core particles; (2) Mix nano-zero-valent iron loaded sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture, and use the electrostatic spraying method to wrap the second mixture on the surface of the core particles to form a 50-80 μm functional layer; (3) Mix sodium acetate with a low-temperature activator to obtain a third mixture, and through centrifugal spray drying, wrap the third mixture on the surface of the functional layer to obtain treatment agent particles; (4) Immerse the treatment agent particles in a glutaraldehyde solution for cross-linking reaction, and after the cross-linking reaction ends, dry to obtain the sodium acetate carbon source water treatment agent. The present invention adopts the supercritical reduction technology: realizing in-situ reduction of zero-valent iron and precise pore loading. Adopting a gradient coating design, the core particles include polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide and a part of the low-temperature activator to achieve a slow-release effect, and the outer core includes sodium acetate and a part of the low-temperature activator, having a rapid release effect. The intermediate functional layer includes nano-zero-valent iron loaded sulfur-doped mesoporous biochar material and 2-pyridinecarboxylic acid, which can block the inhibition of heavy metals on the flora. Both the core particles and the outermost outer core contain a low-temperature activator, so that it still has a high dissolution rate at -25°C. Detailed Embodiments

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0054] The present invention provides a sodium acetate carbon source water treatment agent for sewage treatment, which comprises the following raw materials in parts by weight:

[0055] 65-75 parts of sodium acetate, 7-12 parts of polybutylene succinate, 3-4 parts of low-temperature activator, 0.5-1 part of microbial activator, 8-13 parts of heavy metal adsorbent, 0.5-1 part of COD degrader.

[0056] In some embodiments of the present invention, the sodium acetate carbon source water treatment agent for sewage treatment comprises the following raw materials in parts by weight:

[0057] 68-72 parts of sodium acetate, 9-11 parts of polybutylene succinate, 3-4 parts of low-temperature activator, 0.5-1 part of microbial activator, 9-11 parts of heavy metal adsorbent, 0.5-1 part of COD degrader.

[0058] In some embodiments of the present invention, the particle size of the polybutylene succinate is 50 - 100 μm;

[0059] The low-temperature activator includes one or more of potassium formate, betaine, and potassium thiocyanate;

[0060] The microbial activator includes: 2-pyridinecarboxylic acid.

[0061] In some embodiments of the present invention, the heavy metal adsorbent includes sulfur-doped mesoporous biochar and chlorine-intercalated magnesium-aluminum layered double hydroxide;

[0062] The specific surface area of the sulfur-doped mesoporous biochar is 1250 ± 50 m 2 / g. In the sulfur-doped mesoporous biochar, the mass content of sulfur is 10 - 12%;

[0063] The mass ratio of the sulfur-doped mesoporous biochar to the chlorine-intercalated magnesium-aluminum layered double hydroxide is (5 - 8):(3 - 5).

[0064] In some embodiments of the present invention, the preparation method of the sulfur-doped mesoporous biochar includes the following preparation steps:

[0065] After grinding rice husks, soak them in a hydrochloric acid solution to obtain pretreated rice husk powder;

[0066] Under a nitrogen atmosphere, mix the pretreated rice husk powder with potassium hydroxide and carbonize to obtain carbonized rice husk powder;

[0067] Under a sulfur-containing mixed gas, perform sulfidation to obtain the sulfur-doped mesoporous biochar;

[0068] The concentration of the hydrochloric acid solution is 0.1 - 0.2 mol / L, and the soaking time is 1 - 2 h;

[0069] The mass ratio of the pretreated rice husk powder to potassium hydroxide is 1:(2 - 4), the carbonization temperature is 750 - 850 °C, and the carbonization time is 1 - 2 h;

[0070] The sulfur-containing mixed gas includes hydrogen sulfide and nitrogen, the volume ratio of hydrogen sulfide to nitrogen is 1:(3 - 4), the sulfidation temperature is 600 - 650 °C, and the sulfidation time is 1 - 2 h.

[0071] In some embodiments of the present invention, the preparation method of the chlorine-intercalated magnesium-aluminum layered double hydroxide includes the following steps:

[0072] Mix magnesium nitrate, aluminum nitrate, and water and stir, then add a sodium hydroxide salt solution, perform hydrothermal reaction, and filter;

[0073] The filter residue is impregnated in a hydrochloric acid solution and then dried to obtain the chlorine-intercalated magnesium-aluminum layered double hydroxide;

[0074] In the sodium hydroxide salt solution, the molar ratio of sodium hydroxide to sodium chloride is 0.4:(0.1 - 0.2);

[0075] The molar ratio of magnesium nitrate, aluminum nitrate to sodium hydroxide is (0.2 - 0.3):0.1:0.4;

[0076] The temperature of the hydrothermal reaction is 55 - 65 °C, and the time of the hydrothermal reaction is 10 - 12 h;

[0077] The concentration of the hydrochloric acid solution is 0.1 - 0.2 mol / L, and the impregnation time is 20 - 40 min.

[0078] In some embodiments of the present invention, the COD degrading agent includes nano-zero-valent iron@biochar;

[0079] The nano-zero-valent iron@biochar is a nano-zero-valent iron loaded sulfur-doped mesoporous biochar material.

[0080] In some embodiments of the present invention, the preparation method of the nano-zero-valent iron loaded sulfur-doped mesoporous biochar material comprises the following steps:

[0081] The sulfur-doped mesoporous biochar is placed in a ferric chloride solution and ultrasonically treated to obtain a mixed solution;

[0082] The mixed solution is subjected to a supercritical reduction reaction, followed by passivation and drying to obtain the nano-zero-valent iron loaded sulfur-doped mesoporous biochar;

[0083] The mass-volume ratio of the sulfur-doped mesoporous biochar to the ferric chloride solution is 1 g:(15 - 25 mL), the concentration of the ferric chloride solution is 0.3 - 0.6 mol / L, and the ultrasonic treatment time is 20 - 40 min;

[0084] The pressure of the supercritical reduction reaction is 20 - 25 MPa, and the time of the supercritical reduction reaction is 1 - 2 h;

[0085] The passivation process includes: washing the product obtained from the supercritical reduction reaction with an ethanol solution of polyvinylpyrrolidone, and the mass concentration of the ethanol solution of polyvinylpyrrolidone is 0.1% - 0.2%.

[0086] The present invention also provides a preparation method of the sodium acetate carbon source water treatment agent for sewage treatment as described above, which comprises the following preparation steps:

[0087] (1) Mix polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide, and a low-temperature activator to obtain a first mixture. Spray a binder on the surface of the first mixture to obtain core particles.

[0088] (2) Mix a nano-zero-valent iron-supported sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture. Use the electrostatic spraying method to coat the second mixture on the surface of the core particles to form a 50-80 μm functional layer.

[0089] (3) Mix sodium acetate with a low-temperature activator to obtain a third mixture. Through centrifugal spray drying, coat the third mixture on the surface of the functional layer to obtain treatment agent particles.

[0090] (4) Immerse the treatment agent particles in a glutaraldehyde solution for cross-linking reaction. After the cross-linking reaction ends, dry to obtain the sodium acetate carbon source water treatment agent.

[0091] In some embodiments of the present invention, in step (1), the binder is a hydroxypropyl methylcellulose ethanol solution, and the mass concentration of the hydroxypropyl methylcellulose ethanol solution is 3%-6%;

[0092] The temperature of the spraying is -20~-15°C;

[0093] In step (2), the voltage of the electrostatic spraying method is 20-25 kV, and the flow rate of the electrostatic spraying method is 1-2 mL / min;

[0094] In step (3), the inlet temperature of the centrifugal spray drying is 30-40°C, and the outlet temperature of the centrifugal spray drying is 5-8°C; the mass ratio of the low-temperature activator in step (1) to the low-temperature activator in step (3) is (1-2):1;

[0095] In step (4), the mass concentration of the glutaraldehyde solution is 0.3%-0.6%, the pH is 8-8.5, and the time of the cross-linking reaction is 8-12 s.

[0096] Example 1

[0097] A sodium acetate carbon source water treatment agent for sewage treatment, comprising the following raw materials in parts by weight:

[0098] 65 parts of sodium acetate, 7 parts of polybutylene succinate, 3 parts of potassium formate (low-temperature activator), 0.5 parts of 2-pyridinecarboxylic acid (microbial activator), 5 parts of sulfur-doped mesoporous biochar, 3 parts of chlorine-intercalated magnesium-aluminum layered double hydroxide, and 0.5 parts of nano-zero-valent iron-supported sulfur-doped mesoporous biochar material (COD degrader).

[0099] Among them, the preparation method of the sulfur-doped mesoporous biochar includes the following steps:

[0100] After grinding the rice husks, soak them in a 0.2 mol / L hydrochloric acid solution for 1 h to obtain pretreated rice husk powder;

[0101] Under a nitrogen atmosphere, mix the pretreated rice husk powder with potassium hydroxide (the mass ratio of pretreated rice husk powder to potassium hydroxide is 1:2), and carbonize at 750 °C for 1 h to obtain carbonized rice husk powder;

[0102] Under a mixed gas of hydrogen sulfide and nitrogen (the volume ratio of hydrogen sulfide to nitrogen is 1:4), sulfide at 600 °C for 1 h to obtain the sulfur-doped mesoporous biochar.

[0103] Among them, the preparation method of the chlorine-intercalated magnesium-aluminum layered double hydroxide includes the following steps:

[0104] Mix magnesium nitrate, aluminum nitrate, and water and stir, then add a sodium hydroxide salt solution (the molar ratio of sodium hydroxide to sodium chloride is 0.4:0.1), and carry out a hydrothermal reaction at 55 °C for 10 h, and filter; among them, the molar ratio of magnesium nitrate, aluminum nitrate to sodium hydroxide is 0.2:0.1:0.4.

[0105] Immerse the filter residue in a 0.1 mol / L hydrochloric acid solution for 20 min and dry to obtain the chlorine-intercalated magnesium-aluminum layered double hydroxide.

[0106] Among them, the preparation method of the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material includes the following steps:

[0107] Place the sulfur-doped mesoporous biochar in a 0.3 mol / L ferric chloride solution (the mass-volume ratio of sulfur-doped mesoporous biochar to ferric chloride solution is 1 g:25 mL), and ultrasonicate for 20 min to obtain a mixed solution;

[0108] Under the condition of a pressure of 25 MPa, carry out a supercritical reduction reaction on the mixed solution for 1 h, and then wash the product obtained from the supercritical reduction reaction with an ethanol solution of polyvinylpyrrolidone with a mass concentration of 0.1%, and dry to obtain the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar.

[0109] A preparation method of a sodium acetate carbon source water treatment agent for sewage treatment includes the following preparation steps:

[0110] Mix the above polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide, and a low-temperature activator to obtain a first mixture, and spray an ethanol solution of hydroxypropyl methylcellulose with a mass concentration of 3% on the surface of the first mixture, and the spraying temperature is -20 °C to obtain core particles;

[0111] (2) Mix the nano zero-valent iron loaded sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture, and use the electrostatic spraying method. Among them, the voltage of the electrostatic spraying method is 20 kV, and the flow rate is 1 mL / min, so that the second mixture wraps on the surface of the core particles to form a 40-μm functional layer;

[0112] (3) Mix sodium acetate with a low-temperature activator to obtain a third mixture, and through centrifugal spray drying (the inlet temperature of centrifugal spray drying is 30 °C, and the outlet temperature of centrifugal spray drying is 8 °C), so that the third mixture wraps on the surface of the functional layer to obtain treatment agent particles;

[0113] (4) Immerse the treatment agent particles in a glutaraldehyde solution with a pH of 8 and a mass concentration of 0.3% for 10 s of cross-linking reaction. After the cross-linking reaction ends, dry to obtain the sodium acetate carbon source water treatment agent.

[0114] Among them, the mass ratio of the low-temperature activator in step (1) to the low-temperature activator in step (3) is 1:1.

[0115] Example 2

[0116] A sodium acetate carbon source water treatment agent for sewage treatment, comprising the following raw materials in parts by weight:

[0117] 60 parts of sodium acetate, 12 parts of polybutylene succinate, 4 parts of betaine (low-temperature activator), 0.5 part of 2-pyridinecarboxylic acid (microbial activator), 6 parts of sulfur-doped mesoporous biochar, 4 parts of chlorine-intercalated magnesium-aluminum layered double hydroxide, and 0.5 part of nano zero-valent iron loaded sulfur-doped mesoporous biochar material (COD degrader).

[0118] Among them, the preparation method of the sulfur-doped mesoporous biochar includes the following steps:

[0119] After grinding rice husks, soak them in a 0.1 mol / L hydrochloric acid solution for 2 h to obtain pretreated rice husk powder;

[0120] Under a nitrogen atmosphere, mix the pretreated rice husk powder with potassium hydroxide (the mass ratio of the pretreated rice husk powder to potassium hydroxide is 1:4), and carbonize at a temperature of 850 °C for 1 h to obtain carbonized rice husk powder;

[0121] Under a mixed gas of hydrogen sulfide and nitrogen (the volume ratio of hydrogen sulfide to nitrogen is 1:3), sulfide at a temperature of 650 °C for 1 h to obtain the sulfur-doped mesoporous biochar.

[0122] Among them, the preparation method of the chlorine-intercalated magnesium-aluminum layered double hydroxide includes the following steps:

[0123] After mixing magnesium nitrate, aluminum nitrate, and water and stirring, add a sodium hydroxide salt solution (the molar ratio of sodium hydroxide to sodium chloride is 0.4:0.2), and carry out a hydrothermal reaction at 65 °C for 10 h, then filter; among them, the molar ratio of magnesium nitrate, aluminum nitrate to sodium hydroxide is 0.3:0.1:0.4.

[0124] Immerse the filter residue in a hydrochloric acid solution with a concentration of 0.2 mol / L for 30 min, and then dry to obtain the chlorine-intercalated magnesium-aluminum layered double hydroxide.

[0125] Among them, the preparation method of the nano zero-valent iron-loaded sulfur-doped mesoporous biochar material includes the following steps:

[0126] Place the sulfur-doped mesoporous biochar in a 0.6 mol / L ferric chloride solution (the mass-volume ratio of sulfur-doped mesoporous biochar to ferric chloride solution is 1 g:15 mL), and ultrasonicate for 20 min to obtain a mixed solution;

[0127] Carry out a supercritical reduction reaction on the mixed solution at a pressure of 25 MPa for 1 h, and then wash the product obtained from the supercritical reduction reaction with an ethanol solution of polyvinylpyrrolidone with a mass concentration of 0.2%, and dry to obtain the nano zero-valent iron-loaded sulfur-doped mesoporous biochar.

[0128] A preparation method of a sodium acetate carbon source water treatment agent for sewage treatment includes the following preparation steps:

[0129] Mix the above polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide, and the first part of betaine to obtain a first mixture, and spray an ethanol solution of hydroxypropyl methylcellulose with a mass concentration of 3% on the surface of the first mixture at a spraying temperature of -15 °C to obtain core particles;

[0130] (2) Mix the nano zero-valent iron-loaded sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture, and use the electrostatic spraying method, where the voltage of the electrostatic spraying method is 25 kV and the flow rate is 2 mL / min, so that the second mixture wraps around the surface of the core particles to form a 40 μm functional layer;

[0131] (3) Mix sodium acetate with the second part of betaine to obtain a third mixture, and through centrifugal spray drying (the inlet temperature of centrifugal spray drying is 40 °C, and the outlet temperature of centrifugal spray drying is 5 °C), so that the third mixture wraps around the surface of the functional layer to obtain treatment agent particles;

[0132] (4) Immerse the treatment agent particles in a glutaraldehyde solution with a pH of 8 and a mass concentration of 0.3% for a crosslinking reaction for 10 s. After the crosslinking reaction is completed, dry to obtain the sodium acetate carbon source water treatment agent.

[0133] Among them, the mass ratio of the low-temperature activator in step (1) to the low-temperature activator in step (3) is 1:1.

[0134] Example 3

[0135] It is basically the same as Example 1, except that the weight parts are 75 parts of sodium acetate, 10 parts of polybutylene succinate, 4 parts of potassium thiocyanate, 1 part of 2-pyridinecarboxylic acid (microbial activator), 8 parts of sulfur-doped mesoporous biochar, and 5 parts of nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material (COD degrader) 1 part.

[0136] Among them, the preparation methods of sulfur-doped mesoporous biochar, chloro-intercalated magnesium-aluminum layered double hydroxide, and nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material are the same.

[0137] The preparation method of the above sodium acetate carbon source water treatment agent for sewage treatment includes the following preparation steps:

[0138] Mix the above polybutylene succinate, chloro-intercalated magnesium-aluminum layered double hydroxide and the first part of potassium thiocyanate to obtain a first mixture, and spray a 3% hydroxypropyl methylcellulose ethanol solution on the surface of the first mixture at a spraying temperature of -18°C to obtain core particles;

[0139] (2) Mix the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture, and use the electrostatic spraying method, where the voltage of the electrostatic spraying method is 22 kV and the flow rate is 1 mL / min, so that the second mixture wraps around the surface of the core particles to form a 50-μm functional layer;

[0140] (3) Mix sodium acetate with the second part of potassium thiocyanate to obtain a third mixture, and through centrifugal spray drying (the inlet temperature of centrifugal spray drying is 35°C, and the outlet temperature of centrifugal spray drying is 5°C), so that the third mixture wraps around the surface of the functional layer to obtain treatment agent particles;

[0141] (4) Immerse the treatment agent particles in a glutaraldehyde solution with a pH of 8 and a mass concentration of 0.3%, carry out a cross-linking reaction for 10 s, and after the cross-linking reaction is completed, dry to obtain the sodium acetate carbon source water treatment agent.

[0142] Test Example

[0143] The carbon source release rate, heavy metal adsorption capacity, and low-temperature stability of the sodium acetate carbon source water treatment agents prepared in Test Examples 1-3 are shown in Table 1.

[0144] Table 1 Test results of Examples 1-3

[0145]

[0146] Test method: The carbon source release rate was determined by dynamic dissolution experiment (25°C / 4 h), the heavy metal adsorption capacity was determined by ICP-MS (Pb 2+ / Cd 2+ ), and the low-temperature stability was determined by -20°C freeze / thaw cycle (5 times).

[0147] As can be seen from the data in Table 1, the sodium acetate carbon source water treatment agent provided by the present invention has good heavy metal adsorption, low-temperature stability and appropriate carbon source release rate.

[0148] The sodium acetate carbon source water treatment agents prepared in Examples 1-3 were put into the simulated wastewater to test their treatment effects, and the test results are shown in Table 2.

[0149] Test conditions: water temperature 5°C (simulating alpine regions in winter); inlet pollutant concentration TN = 45 mg / L, COD = 180 mg / L (containing 20% of refractory organic matter), Pb 2+ 8 ppm, Cr(VI) 6 ppm).

[0150] Dosage, 80 mg / L.

[0151] Table 2 Test results of treatment effects of Examples 1-3

[0152]

[0153] As can be seen from the test results in Table 2, the denitrification efficiency of the sodium acetate carbon source water treatment agent provided by the present invention is ≥95%, and at a low temperature (5°C), it still maintains a high heavy metal / COD removal rate.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific embodiments of the present invention, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A sodium acetate carbon source water treatment agent for sewage treatment, characterized in that, Comprising the following raw materials in parts by weight: 65 - 75 parts of sodium acetate, 7 - 12 parts of polybutylene succinate, 3 - 4 parts of low-temperature activator, 0.5 - 1 part of microbial activator, 8 - 13 parts of heavy metal adsorbent, 0.5 - 1 part of COD degrader; Among them, the particle size of the polybutylene succinate is 50 - 100 μm; the low-temperature activator includes one or more of potassium formate, betaine, and potassium thiocyanate; the microbial activator includes picolinic acid; the heavy metal adsorbent includes sulfur-doped mesoporous biochar and chlorine-intercalated magnesium-aluminum layered double hydroxide; the specific surface area of the sulfur-doped mesoporous biochar is 1250 ± 50 m 2 / g, in the sulfur-doped mesoporous biochar, the mass content of sulfur is 10 - 12%; the mass ratio of the sulfur-doped mesoporous biochar to the chlorine-intercalated magnesium-aluminum layered double hydroxide is (5 - 8):(3 - 5); The preparation method of the sulfur-doped mesoporous biochar comprises the following preparation steps: After grinding rice husks, soak them in hydrochloric acid solution to obtain pretreated rice husk powder; Under a nitrogen atmosphere, mix the pretreated rice husk powder with potassium hydroxide and carbonize to obtain carbonized rice husk powder; the mass ratio of the pretreated rice husk powder to potassium hydroxide is 1:(2 - 4); Sulfurize under a sulfur-containing mixed gas to obtain the sulfur-doped mesoporous biochar; The preparation method of the chlorine-intercalated magnesium-aluminum layered double hydroxide comprises the following steps: Mix magnesium nitrate, aluminum nitrate and water and stir, then add sodium hydroxide salt solution and carry out hydrothermal reaction, and filter; Immerse the filter residue in hydrochloric acid solution and dry to obtain the chlorine-intercalated magnesium-aluminum layered double hydroxide; In the sodium hydroxide salt solution, the molar ratio of sodium hydroxide to sodium chloride is 0.4:(0.1 - 0.2); The molar ratio of magnesium nitrate, aluminum nitrate to sodium hydroxide is (0.2 - 0.3):0.1:0.4; The COD degrader includes nano-zero-valent iron@biochar; the nano-zero-valent iron@biochar is a nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material.

2. The sodium acetate carbon source water treatment agent for sewage treatment according to claim 1, wherein Comprising the following raw materials in parts by weight: 68 - 72 parts of sodium acetate, 9 - 11 parts of polybutylene succinate, 3 - 4 parts of low-temperature activator, 0.5 - 1 part of microbial activator, 9 - 11 parts of heavy metal adsorbent, 0.5 - 1 part of COD degrader.

3. A sodium acetate carbon source water treatment agent for sewage treatment according to claim 1, characterized in that, The concentration of the hydrochloric acid solution is 0.1 - 0.2 mol / L, and the soaking time is 1 - 2 h; The carbonization temperature is 750 - 850 °C, and the carbonization time is 1 - 2 h; The sulfur-containing mixed gas includes hydrogen sulfide and nitrogen, the volume ratio of hydrogen sulfide to nitrogen is 1:(3 - 4), the sulfuration temperature is 600 - 650 °C, and the sulfuration time is 1 - 2 h.

4. A sodium acetate carbon source water treatment agent for sewage treatment according to claim 1, characterized in that, The temperature of the hydrothermal reaction is 55 - 65 °C, and the hydrothermal reaction time is 10 - 12 h; The concentration of the hydrochloric acid solution is 0.1 - 0.2 mol / L, and the impregnation time is 20 - 40 min.

5. A sodium acetate carbon source water treatment agent for sewage treatment according to claim 4, characterized in that, The preparation method of the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar material comprises the following steps: Place the sulfur-doped mesoporous biochar in ferric chloride solution and ultrasonicate to obtain a mixed solution; Carry out a supercritical reduction reaction on the mixed solution, and then passivate and dry to obtain the nano-zero-valent iron-loaded sulfur-doped mesoporous biochar; The mass-volume ratio of the sulfur-doped mesoporous biochar to the ferric chloride solution is 1 g:(15 - 25 mL), the concentration of the ferric chloride solution is 0.3 - 0.6 mol / L, and the ultrasonication time is 20 - 40 min; The pressure of the supercritical reduction reaction is 20 - 25 MPa, and the supercritical reduction reaction time is 1 - 2 h; The passivation process includes: washing the product obtained from the supercritical reduction reaction with an ethanol solution of polyvinylpyrrolidone, where the mass concentration of the ethanol solution of polyvinylpyrrolidone is 0.1% - 0.2%.

6. The preparation method of a sodium acetate carbon source water treatment agent for sewage treatment according to any one of claims 1-5, characterized in that, It includes the following preparation steps: (1) Mix polybutylene succinate, chlorine-intercalated magnesium-aluminum layered double hydroxide, and a low-temperature activator to obtain a first mixture, and spray a binder on the surface of the first mixture to obtain core particles; (2) Mix the nano-zero-valent iron-supported sulfur-doped mesoporous biochar material with 2-pyridinecarboxylic acid to obtain a second mixture, and use the electrostatic spraying method to wrap the second mixture on the surface of the core particles to form a 50 - 80 μm functional layer; (3) Mix sodium acetate with a low-temperature activator to obtain a third mixture, and through centrifugal spray drying, wrap the third mixture on the surface of the functional layer to obtain treatment agent particles; (4) Immerse the treatment agent particles in a glutaraldehyde solution for cross-linking reaction. After the cross-linking reaction ends, dry to obtain the sodium acetate carbon source water treatment agent.

7. The preparation method of a sodium acetate carbon source water treatment agent for sewage treatment according to claim 6, characterized in that, In step (1), the binder is an ethanol solution of hydroxypropyl methylcellulose, and the mass concentration of the ethanol solution of hydroxypropyl methylcellulose is 3% - 6%; The temperature of the spraying is -20~-15°C; In step (2), the voltage of the electrostatic spraying method is 20 - 25 kV, and the flow rate of the electrostatic spraying method is 1 - 2 mL / min; In step (3), the inlet temperature of the centrifugal spray drying is 30 - 40°C, and the outlet temperature of the centrifugal spray drying is 5 - 8°C; the mass ratio of the low-temperature activator in step (1) to the low-temperature activator in step (3) is (1 - 2):1; In step (4), the mass concentration of the glutaraldehyde solution is 0.3% - 0.6%, the pH is 8 - 8.5, and the time of the cross-linking reaction is 8 - 12 s.

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