Nanoscale sludge settling accelerator, preparation method and application thereof

Abstract

The application belongs to the field of sewage treatment, and discloses a nano sludge settling accelerator, a preparation method and application. The nano sludge settling accelerator comprises the following components and component mass ratios: 0.01-0.1 parts of A component nano-scale ferroferric oxide particles, 5-15 parts of B component high polymer coagulant aid, 15-30 parts of C component inorganic salt solution, 0.1-0.2 parts of D component preservative stabilizer, and 55-80 parts of water. The sludge settling effect is good, the dosing amount is small, the nano sludge settling accelerator is non-toxic to microorganisms, and can be used for a long time, so that the long-term stable operation of a sewage plant can be realized.

Description

Technical Field

[0001] This invention belongs to the field of wastewater purification and treatment in the field of environmental protection technology, and particularly relates to a nano-accelerating sludge settling agent, its preparation method and application. Background Technology

[0002] The activated sludge process is the primary treatment method used by the vast majority of wastewater treatment plants both domestically and internationally. The stable operation of activated sludge is a decisive factor affecting wastewater treatment efficiency and cost. Difficulty in sludge settling, especially in northern regions where low winter temperatures can easily lead to sludge bulking, results in slow sludge settling in the secondary sedimentation tank, making sludge-water separation difficult. This phenomenon, known as sludge floating and sludge runoff, not only affects the stable operation of the biological treatment system but also poses a significant challenge to subsequent advanced treatment processes, potentially even affecting effluent discharge standards and causing significant environmental impact, while simultaneously increasing the operating costs of the wastewater treatment plant.

[0003] Currently, commonly used flocculants on the market, such as inorganic flocculants like iron and aluminum salts, and high-molecular-weight organic flocculants like polyacrylamide, can accelerate the settling of difficult-to-settle sludge through charge neutralization, adsorption, and bridging. However, these agents have the following drawbacks:

[0004] (1) Commonly used aluminum salts, such as PAC, require a large dosage. Long-term and large-scale use will cause aluminum salts to accumulate in the system, which has a great toxic effect on microorganisms, reduces sludge activity, and further deteriorates sludge activity, which will have an adverse impact on the operation of the wastewater treatment plant.

[0005] (2) Conventional iron salts, such as polyferric sulfate, require large dosages. Excessive dosage will increase the amount of sludge, affect the pH value of the effluent, increase the color of the effluent, and cause serious corrosion to the relevant equipment of the sewage treatment plant.

[0006] (3) The addition of organic polymers (such as polyacrylamide) can accelerate sludge settling, but the residual monomer acrylamide in polyacrylamide is toxic to microorganisms, which reduces sludge activity and increases the viscosity of the wastewater treatment system. In addition, it may increase the risk of ammonia nitrogen rise. Long-term addition is not conducive to the stable operation of wastewater treatment plants.

[0007] In response to the actual operational needs of wastewater treatment plants and the drawbacks of conventional reagents, such as large dosage and biological toxicity, the development of a product with good sludge settling effect, small dosage, non-toxicity to microorganisms, and long-term use is urgently needed to help wastewater treatment plants achieve long-term stable operation. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a nano-accelerated sludge settling agent, its preparation method, and its application. It exhibits good sludge settling effect, requires a small dosage, is non-toxic to microorganisms, and can be used long-term, helping wastewater treatment plants achieve long-term stable operation.

[0009] This invention provides a nano-accelerated sludge settling agent, comprising the following components and their mass ratios as follows: Component A: 0.01-0.1 parts of nano-sized iron oxide particles; Component B: 5-15 parts of polymeric coagulant aid; Component C: 15-30 parts of inorganic salt solution; Component D: 0.1-0.2 parts of corrosion inhibitor and stabilizer; and 55-80 parts of water.

[0010] Furthermore, component B contains one or more of hexadecyltrimethylammonium chloride, polydimethyldiallylammonium chloride, dimethyldiallylammonium chloride-acrylamide polymer, and polyamines.

[0011] Furthermore, the inorganic salt solution of component C contains two or more of ferrous sulfate, aluminum sulfate, ferrous chloride, and aluminum chloride.

[0012] Furthermore, the D component corrosion stabilizer comprises one or more of the following: micronized iron powder, isothiazolinone, sodium sulfite, citric acid, and disodium ethylenediaminetetraacetate.

[0013] Furthermore, the particle size of the nano-sized iron oxide particles in component A is between 20-100 nm.

[0014] Another object of the present invention is to provide a method for preparing a nano-accelerated settling agent that accelerates sludge settling, the method comprising the following steps:

[0015] Step 1: Preparation of nano-sized Fe3O4 particles of component A: The iron salt mixture was dissolved in 0.5 mol / L dilute hydrochloric acid at a mass ratio of 1:5 to 1:10 under an inert atmosphere. The iron salt mixture consisted of FeCl3·6H2O and FeSO4·7H2O mixed in a molar ratio of 2:1 to 3:1. 2 mol / L ammonia was slowly added dropwise to the solution while mechanically stirring at 500 to 2000 rpm until the pH of the solution rose to 9. The resulting solution was stirred and heated at 85°C for 2 to 4 hours. The product was magnetically separated, washed three times with deionized water and ethanol respectively, and dried in a vacuum oven at 60°C. The resulting nano-Fe3O4 particles had a particle size between 20 and 100 nm.

[0016] Step 2: Add 5-15 parts of the polymeric coagulant of component B to 55-80 parts of water, and stir at 50-150 r / min until completely mixed to obtain the nano-fast settling agent base liquid; wherein, component B contains one or more of hexadecyltrimethylammonium chloride, polydimethyldiallylammonium chloride, dimethyldiallylammonium chloride-acrylamide polymer and polyamine.

[0017] Step 3: Add 15-30 parts of the inorganic salt of component C to the nano-precipitant base solution obtained in step 2, control the temperature at 30-40℃, seal the container, and stir at 150-200 r / min in an anaerobic environment until completely dissolved. Adjust the pH to 3 with hydrochloric acid and set aside for use. The inorganic salt solution of component C contains two or more of ferrous sulfate, aluminum sulfate, ferrous chloride, and aluminum chloride.

[0018] Step 4: Add 0.01 to 0.1 parts of the nano-iron oxide particles obtained in Step 1 to the nano-precipitant base liquid, stir for 1 to 2 hours at a speed of 500 to 1000 r / min, and simultaneously use ultrasonic waves to assist in the dispersion of the nano-particles.

[0019] Step 5: Add 0.1 to 0.2 parts of component D corrosion stabilizer to the mixture obtained in step 4, stir evenly, and mature for 48 hours to obtain nano-accelerated settling agent; wherein, component D corrosion stabilizer contains one or more of micron iron powder, isothiazolinone, sodium sulfite, citric acid, and disodium ethylenediaminetetraacetate.

[0020] A municipal wastewater treatment method, wherein the municipal wastewater treatment method uses the nano-accelerated sludge settling agent described in the above technical solution.

[0021] A method for treating wastewater from textile, printing and dyeing, papermaking, pharmaceutical, food processing, slaughtering, chemical, pesticide, steel, leather, electroplating, and other industries, wherein the wastewater treatment method for textile, printing and dyeing, papermaking, pharmaceutical, food processing, slaughtering, chemical, pesticide, steel, leather, electroplating, and other industries uses the nano-accelerating sludge settling agent described in the above technical solution.

[0022] A method for treating rural sewage and decentralized sewage, wherein the rural sewage and decentralized sewage treatment method uses the nano-accelerating sludge settling agent described in the above technical solution.

[0023] To demonstrate the technical effectiveness of this invention, a real wastewater treatment plant experiment was conducted:

[0024] In a wastewater treatment plant in Guangdong Province that mixes industrial and domestic wastewater, the sludge at the end of the aerobic tank of the sludge-water mixture exhibited sludge bulking, with a sludge settling index (SVI) of approximately 180 ml / g, indicating difficulty in settling and sludge overflow into the secondary sedimentation tank, affecting the normal operation of the wastewater treatment plant. The nano-accelerated settling agent prepared in Example 1 of this invention was applied to the sludge-water mixture of this plant. A blank control group was set up. A sludge settling experiment was conducted using a 1000 ml graduated cylinder. After 0.5 hours of sedimentation, the supernatant was analyzed to measure chemical oxygen demand, temperature, suspended solids concentration, and total phosphorus for comparison. The test results are shown in Tables 1 and 2.

[0025] Table 1: Effect of nano-accelerated settling agent on the settling performance of expanded sludge in wastewater treatment plants (dosage 25 mg / L)

[0026]

[0027] As can be seen from the results in the table above, compared with the control group, the addition of nano-sedimentation agent can greatly improve the settling performance of difficult-to-settle sludge and accelerate the sludge settling speed.

[0028] Table 2: Effect of nano-accelerated settling agent on the water quality improvement of supernatant after sedimentation in wastewater treatment plants (dosage 25 mg / L)

[0029] parameter Chemical oxygen demand suspended matter Total phosphorus Turbidity unit mg / L mg / L mg / L NTU blank 106.7 63.81 1.49 52.80 Example 1 51.3 12.65 1.07 18.48

[0030] The results in the table above show that the nano-accelerated settling agent not only accelerates sludge settling but also improves the water quality of the supernatant. The supernatant in the dosing group was observed to be clearer than that in the control group, with significant reductions in both suspended solids concentration and turbidity. Furthermore, the addition of the nano-accelerated settling agent removed some of the chemical oxygen demand and also aided in phosphorus removal, alleviating the pressure on subsequent advanced treatment and reducing the need for subsequent chemicals.

[0031] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows:

[0032] 1. Significantly accelerates sludge settling speed: The product of this invention can quickly neutralize the negative charge on the surface of sludge flocs, and through the adsorption and bridging effect of organic-inorganic components, sludge rapidly forms large flocs with nanoparticles as crystal nuclei, thereby achieving rapid sludge settling.

[0033] 2. Improve effluent quality and reduce pressure on downstream wastewater treatment processes: The product of this invention can adsorb fine suspended solids in wastewater onto sludge flocs through multiple functions such as charge neutralization, adsorption bridging, and net capture and sweeping, thereby separating them from water, making the effluent clearer, reducing the chemical chlorine demand, suspended solids content, and turbidity of the effluent, and reducing the pressure on downstream deep treatment.

[0034] 3. Non-toxic to microorganisms and will not affect sludge activity: All products of this invention are made of microorganism-friendly materials. Long-term addition will not have any impact on microorganisms. While accelerating sedimentation, it will not have any negative impact on the operation of sewage treatment plants.

[0035] 4. It has an auxiliary phosphorus removal function: While accelerating sludge settling, the product of this invention can also remove a portion of total phosphorus through chemical reaction and adsorption, thus playing a certain role in phosphorus removal and reducing the amount of phosphorus removal agent used.

[0036] 5. Emergency treatment assistance for wastewater treatment plants: The product of this invention can quickly achieve sludge-water separation. Therefore, when industrial or domestic wastewater treatment plants are subjected to water volume and quality shocks, sludge poisoning, sludge expansion, floating sludge, or other situations, it can be added as an emergency measure to prevent sludge loss and ensure the stable operation of the wastewater treatment plant. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] Example 1:

[0039] (1) A mixture of iron salts was dissolved in 0.5 mol / L dilute hydrochloric acid at a mass ratio of 1:8 under an inert atmosphere. The iron salt mixture consisted of FeCl3·6H2O and FeSO4·7H2O mixed in a molar ratio of 2.5:1. 2 mol / L ammonia was slowly added dropwise to the solution while mechanically stirring at 1500 rpm until the pH of the solution reached 9. The resulting solution was heated and stirred at 85°C for 3 hours. The product was magnetically separated, washed three times alternately with deionized water and ethanol, and dried in a vacuum oven at 60°C. The obtained nano-Fe3O4 particles had a particle size between 30-80 nm.

[0040] (2) Add 0.1 parts of hexadecyltrimethylammonium chloride, 0.9 parts of polyamine, and 9 parts of polydimethyldiallylammonium chloride to 72.3 parts of water and stir at 100 r / min until completely mixed to obtain nano-precipitant base liquid.

[0041] (3) Add 5 parts aluminum chloride and 12.5 parts ferrous chloride to the base solution obtained in step 2, control the temperature at 30°C, seal the container, and stir at 180 r / min in an anaerobic environment until completely dissolved. Adjust the pH to 3 with hydrochloric acid and set aside for later use.

[0042] (4) Add 0.05 parts of nano-iron oxide obtained in step 1 to the nano-precipitant base liquid, stir for 1.5 hours at a speed of 800 r / min, and use ultrasonic-assisted dispersion to ensure that the nanoparticles are uniformly dispersed in the solution.

[0043] (5) Add 0.15 parts of corrosion stabilizer (including 0.05 parts of micron iron powder, 0.02 parts of isothiazolinone, 0.05 parts of sodium sulfite and 0.03 parts of disodium ethylenediaminetetraacetate) to the solution obtained in step 4, stir evenly, and mature for 48 hours to obtain nano-accelerated settling agent.

[0044] Example 2

[0045] (1) A mixture of iron salts was dissolved in 0.5 mol / L dilute hydrochloric acid at a mass ratio of 1:5 under an inert atmosphere. The iron salt mixture consisted of FeCl3·6H2O and FeSO4·7H2O mixed in a molar ratio of 2:1. 2 mol / L ammonia was slowly added dropwise to the solution while mechanically stirring at 500 rpm until the pH of the solution reached 9. The resulting solution was heated and stirred at 85°C for 2 hours. The product was magnetically separated, washed three times alternately with deionized water and ethanol, and dried in a vacuum oven at 60°C. The obtained nano-Fe3O4 particles had a particle size between 20-50 nm.

[0046] (2) Add 0.15 parts of hexadecyltrimethylammonium chloride, 4.35 parts of dimethyl diallyl ammonium chloride-acrylamide copolymer and 0.5 parts of polyamine to 64.79 parts of water and stir at 50 r / min until completely mixed to obtain nano-sedimentary liquid base.

[0047] (3) Add 22 parts of ferrous sulfate and 8 parts of aluminum sulfate to the base solution obtained in step 1, control the temperature at 40℃, seal the container, and stir at 200r / min in an anaerobic environment until completely dissolved. Adjust the pH to 3 with hydrochloric acid and set aside for later use.

[0048] (4) Add 0.01 parts of the nano-iron oxide particles obtained in step 1 to the nano-precipitant base liquid, stir for 1 hour at a speed of 500 r / min, and simultaneously use ultrasonic waves to disperse the nano-particles.

[0049] (5) Add 0.2 parts of corrosion stabilizer (including 0.08 parts of micron iron powder, 0.02 parts of isothiazolinone, 0.02 parts of citric acid and 0.08 parts of sodium sulfite) to the solution obtained in step 4, stir evenly, and mature for 48 hours to obtain nano-accelerated settling agent.

[0050] Example 3

[0051] (1) A mixture of iron salts was dissolved in 0.5 mol / L dilute hydrochloric acid at a mass ratio of 1:10 under an inert atmosphere. The iron salt mixture consisted of FeCl3·6H2O and FeSO4·7H2O mixed in a molar ratio of 3:1. 2 mol / L ammonia was slowly added dropwise to the solution while mechanically stirring at 2000 rpm until the pH of the solution reached 9. The resulting dark-colored solution was heated and stirred at 85°C for 4 hours. The product was magnetically separated, washed three times each with deionized water and ethanol, and dried in a vacuum oven at 60°C. The obtained nano-Fe3O4 particles had a particle size between 50-100 nm.

[0052] (2) Add 0.1 parts of hexadecyltrimethylammonium chloride, 1 part of polyamine, 2 parts of polydimethyldiallylammonium chloride, and 11.9 parts of dimethyldiallylammonium chloride-acrylamide polymer to 79.8 parts of water and stir at 150 r / min until completely mixed to obtain nano-precipitant base liquid.

[0053] (3) Add 4 parts of ferrous chloride and 1 part of aluminum chloride to the base solution obtained in step 1, control the temperature at 30°C, seal the container, and stir at 150 r / min in an anaerobic environment until completely dissolved. Adjust the pH to 3 with hydrochloric acid and set aside for later use.

[0054] (4) Add 0.1 part of the nano-iron oxide obtained in step 1 to the nano-precipitant base liquid, stir for 2 hours at a speed of 1000 r / min, and simultaneously use ultrasonic waves to disperse the nanoparticles.

[0055] (5) Add 0.1 parts of corrosion stabilizer (including 0.02 parts of micron iron powder, 0.04 parts of isothiazolinone, 0.01 parts of disodium ethylenediaminetetraacetate and 0.03 parts of sodium sulfite) to the solution obtained in step 4, stir evenly and mature for 48 hours to obtain nano-accelerated settling agent.

[0056] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A nano-superpacer for accelerating sludge settling, characterized in that, The nano-speed settling agent comprises the following components and component mass ratio: 0.01-0.1 parts of A component nano-sized ferroferric oxide particles, 5-15 parts of B component high polymer coagulant aid, 15-30 parts of C component inorganic salt solution, 0.1-0.2 parts of D component preservative stabilizer, and 55-80 parts of water. The preparation method of the nano-speed settling agent comprises the following steps: Step 1: Preparation of A component nano-sized ferroferric oxide particles: an iron salt mixture and 0.5 mol / L dilute hydrochloric acid are dissolved in a mass ratio of 1:5-1:10 under an inert atmosphere, wherein the iron salt mixture is a mixture of FeCl3·6H2O and FeSO4·7H2O in a molar ratio of 2:1-3:1, 2 mol / L ammonia water is slowly added dropwise into the solution, the mechanical stirring speed is 500-2000 rpm, until the pH of the solution rises to 9, the obtained solution is heated and stirred at 85°C for 2-4 h, the product is magnetically separated, washed with deionized water and ethanol for 3 times respectively, and dried in a vacuum oven at 60°C, the obtained nano Fe3O4 particles have a particle size of 20-100 nm; Step 2: 5-15 parts of B component high polymer coagulant aid is added into 55-80 parts of water, stirred at a speed of 50-150 r / min until completely mixed and uniform, and a nano-speed settling agent base solution is obtained; wherein the B component contains one or more of cetyltrimethylammonium chloride, polydimethyl diallyl ammonium chloride, dimethyl diallyl ammonium chloride-acrylamide polymer and polyamine; Step 3: 15-30 parts of C component inorganic salt is added into the nano-speed settling agent base solution obtained in step 2, the temperature is controlled at 30-40°C, the container is sealed, stirring is carried out in an oxygen-free environment at a speed of 150-200 r / min until completely dissolved, and the pH is adjusted to 3 with hydrochloric acid for standby use; wherein the C component inorganic salt solution contains two or more of ferrous sulfate, aluminum sulfate, ferrous chloride and aluminum chloride; Step 4: 0.01-0.1 parts of nano ferroferric oxide particles obtained in step 1 is added into the nano-speed settling agent base solution, stirring is carried out at a speed of 500-1000 r / min for 1-2 h, and the nano particles are dispersed by ultrasonic assistance; Step 5: 0.1-0.2 parts of D component preservative stabilizer is added into the mixed solution prepared in step 4, stirred uniformly, and the nano-speed settling agent is obtained after aging for 48 h; wherein the D component preservative stabilizer contains one or more of micron iron powder, isothiazolinone, sodium sulfite, citric acid and ethylenediaminetetraacetic acid.

2. A method of municipal sewage treatment, characterized by, The municipal sewage treatment method uses the nano-speed settling agent for accelerating sludge settling according to claim 1.

3. A method for treating wastewater from textile, printing and dyeing, papermaking, pharmaceutical, food processing, slaughter, chemical industry, pesticide, steel, leather, electroplating, characterized in that, The textile, printing and dyeing, papermaking, pharmaceutical, food processing, slaughter, chemical, pesticide, steel, leather, electroplating wastewater treatment method uses the nano-speed settling agent for accelerating sludge settling according to claim 1.

4. A method for treating rural sewage and decentralized sewage, characterized by, The rural and decentralized sewage treatment method uses the nano-speed settling agent for accelerating sludge settling according to claim 1.

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