Sludge stabilizer and sludge dewatering process

Abstract

The present application provides a kind of sludge stabilizer and sludge dewatering process, the sludge stabilizer of the present application includes by mass fraction: 10 parts of magnesium carbonate, 20 parts of calcium carbonate, 10 parts of aluminum sulfate, 20 parts of potassium carbonate, 20 parts of alumina, 20 parts of calcium oxide.The present application is when carrying out sludge dewatering, sludge stabilizer is added to sludge and is fully stirred with sludge, the addition amount of the sludge stabilizer is 20%~40% of absolute dry mud amount;Sludge obtained in the above step is added with the organic dewatering agent, so that the concentration of organic dewatering agent in sludge is 0.02%~0.25%, and pressure filtration dewatering is carried out using plate and frame filter press.The present application adopts stabilizer special for sludge dewatering auxiliary reagent of plate and frame filter press, increases the squeezing effect of plate and frame dewatering squeezing stage, can destroy some colloidal particles in sludge and the molecular structure of original polyacrylamide of sludge, reduces the viscosity of sludge.

Description

Technical Field

[0001] This invention belongs to the field of sludge dewatering technology, specifically a sludge stabilizer and a sludge dewatering process. Background Technology

[0002] Municipal sewage sludge, when released into the environment without proper treatment and disposal, directly causes secondary pollution to groundwater, water bodies, and the atmosphere. This not only reduces the effective treatment capacity of sewage treatment systems but also poses a serious threat to the ecological environment and human activities. The large-scale generation of sewage sludge has made its treatment and disposal increasingly prominent, gradually becoming a major challenge for various sewage treatment industries in China. Compared to the rapid development of sewage treatment, my country's sludge treatment and disposal technology is still in its infancy. The main methods of sludge treatment and disposal in my country include land application, incineration and building material utilization, and landfill. Sludge drying is generally carried out using drying sheds and drying boxes.

[0003] Due to the characteristics of sludge, the following problems mainly exist in the sludge treatment and disposal process:

[0004] On the one hand, the sludge entering the plant has a water content of about 85%, and the water inside the microbial cells in the sludge is difficult to evaporate during the drying process. On the other hand, the sludge entering the plant is treated by the addition of flocculants and other agents during the dewatering process, which makes the sludge characteristics more like a "viscous" semi-solid and semi-liquid state, resulting in the current situation of unstable operation and low efficiency of the drying process.

[0005] During the heat exchange drying process, sludge emits odors to varying degrees, affecting the production workshop and factory environment and posing environmental risks to enterprises. Because the dried sludge carries odors, the resource recycling and reuse industry of dried sludge is interrupted, such as in brick factories and in replacing low-calorific-value inferior coal for combustion, resulting in resource waste.

[0006] The method of evaporating water from sludge by fuel heating is inefficient, costly, and difficult to maintain.

[0007] For example, patent document CN108947202A discloses a sludge composite thermal drying system and method, which uses the greenhouse effect of a transparent drying shed and uses the waste heat of steam from a power plant as an auxiliary heat source for drying. However, although this method improves the dewatering efficiency of sludge drying to a certain extent, it has problems such as limited drying capacity, low drying efficiency, and volatilization of fermentation odors. Furthermore, the process design does not take into account the extremely cold climate in the area, resulting in shutdown during the entire heating season.

[0008] Patent document CN217535795U discloses a device for drying sludge using a drying box. This device can remove moisture from the sludge inside the sludge box, thus enabling the sludge to be dried quickly. However, since the device uses electricity for heating, the energy consumption during the sludge drying process is high. Furthermore, because the sludge entering the sewage treatment plant has a high water content and high viscosity, the sludge cutting and cutting effect after drying is poor, resulting in low drying efficiency.

[0009] With the significant increase in sludge treatment volume, the use of a single drying shed or drying box for sludge drying can no longer meet the needs of sludge drying treatment.

[0010] In order to achieve the goals of "reduction, stabilization, harmlessness and resource utilization" in municipal sludge treatment, it is necessary to propose a new sludge drying treatment scheme. Summary of the Invention

[0011] The purpose of this invention is to provide a sludge stabilizer that disrupts some colloidal particles in the sludge and the original molecular structure of polyacrylamide in the sludge, thereby reducing the sludge's viscosity. Simultaneously, it provides a sludge dewatering process specifically designed for plate and frame filter presses, enhancing the pressing effect during the plate and frame dewatering stage.

[0012] The present invention is as follows:

[0013] In a first aspect, the present invention provides a sludge stabilizer, wherein the sludge stabilizer comprises, by mass fraction: 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide, with the error in the proportion of each component ≤1%.

[0014] In this application, the sludge stabilizer is prepared by uniformly mixing magnesium carbonate, calcium carbonate, aluminum sulfate, potassium carbonate, aluminum oxide, and calcium oxide according to the product composition ratio to obtain the sludge stabilizer.

[0015] The sludge stabilizer provided in this application is a mixture of various inorganic compounds, which appears as gray powder particles with a bulk density of approximately 900 kg / m³. 3 The moisture content is approximately 5%, and the product has a pH value of 8-9 in a 0.1% deionized aqueous solution. The moisture content is derived from the moisture inherent in the raw materials.

[0016] The stabilizer provided in this application enhances the pressing effect during the plate and frame dewatering stage. When applied to sludge, it disrupts some colloidal particles and the molecular structure of the original polyacrylamide in the sludge, reducing sludge viscosity. It stabilizes sludge properties even with complex sludge origins. Within the plate and frame dewatering system, it acts as a framework, increasing filtration channels for sludge dewatering. It disrupts sludge cell walls, facilitating the removal of intracellular and extracellular free water. It removes odors generated by adsorbing some of the sludge, without altering the quality of the filtered water.

[0017] Secondly, this application also provides a sludge dewatering process, comprising the following steps:

[0018] First, the stabilizer is used to adjust the properties of the sludge, making the chemical properties of the sludge material more stable and uniform. The specific process is as follows:

[0019] S1. Add the sludge stabilizer to the sludge and mix it thoroughly. The amount of sludge stabilizer added is 20% to 40% of the dry sludge weight.

[0020] Based on the above technical solution, this application adds the organic dewatering agent to the sludge after adding the stabilizer, as follows:

[0021] S2. Add an organic dewatering agent to the sludge obtained in S1, so that the concentration of the organic dewatering agent in the sludge is 0.02% to 0.25%.

[0022] S3. The sludge obtained in step S2 is fed into a plate and frame filter press for dewatering.

[0023] The organic dehydrating agent comprises, by mass fraction: 20 parts dimethyl diallyl ammonium chloride, 30 parts acryloyloxyethyl trimethyl ammonium chloride, and 50 parts polyamine. The organic dehydrating agent is prepared by mixing dimethyl diallyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, and polyamine according to the product composition ratio, heating to 50°C and reacting for 30 minutes, then drying, pulverizing, and granulating to obtain a dry powder of the organic dehydrating agent.

[0024] The organic dehydrating agent provided in this application is mainly composed of a characteristic cationic water-soluble polymer. It appears as a white powder, dissolving into a colorless, transparent to pale white liquid. The organic dehydrating agent is a low to medium molecular weight organic compound, a cationic mixture, with a bulk density of approximately 600 kg / m³. 3 It has a pH of approximately 6-7 in a 0.1% deionized aqueous solution and a viscosity of approximately 300 mPa·s in an aqueous solution (0.3% tap water, 20℃), indicating good water solubility.

[0025] Furthermore, the method for preparing the organic dehydrating agent before adding it to the sludge is as follows: add the organic dehydrating agent powder to clean water at 15-30°C and continuously stir to dissolve it, so as to dissolve the organic dehydrating agent powder into a storage aqueous solution of 0.25% to 0.50%.

[0026] When the stored aqueous solution is added to the sludge, it must be diluted online with 5 to 10 times the amount of water before being metered and added to the sludge.

[0027] It should be noted that the organic dehydrating agent of this application should be used as soon as possible after dissolution, and the storage time should not exceed 24 hours. Attention should be paid to the quality of the dissolving water. Use clean water for dissolution. If the pH value of the dissolving water is too acidic / alkaline, the water hardness is high, the SS content is high, the COD is high, the microbial content is high, the residual chlorine is high, or the water temperature is too high, it will affect the dissolution and use effect of the product. If it is dissolved manually, the powder particles should be evenly sprinkled into the water during dissolution. Adding the material too quickly can easily cause clumping. Avoid miscibility with anionic flocculants.

[0028] In this application, preferably, the device for adding the organic dewatering agent to the sludge is a positive displacement pump; more preferably, the positive displacement pump is a screw pump. Using a positive displacement pump avoids the destruction of the polymer chains by mechanical shear forces. The organic dewatering agent can be added continuously or in batches.

[0029] The key technical effects of this application are:

[0030] 1. This application uses a stabilizer specifically designed as an auxiliary agent for sludge dewatering in plate and frame filter presses. It enhances the pressing effect during the plate and frame dewatering stage, breaking down some colloidal particles in the sludge and the molecular structure of the original polyacrylamide in the sludge, thus reducing sludge viscosity. It stabilizes the properties of sludge from complex sources. Within the plate and frame filter press cavity, it acts as a framework, increasing the filtration channels for sludge dewatering. It disrupts the sludge cell walls, making it easier for intracellular and extracellular free water to escape, and removing the odor produced by adsorbing some of the sludge. It does not alter the quality of the filtered water.

[0031] 2. The sludge dewatering process adopted in this application uses the stabilizer and organic dewatering agent of this application. There is no need to add lime, iron salt and sludge conditioner during sludge dewatering. Only environmentally friendly agents need to be added for direct sludge dewatering. The dosage is small, the cost is low, the effect is good, the sludge filter cake has a moisture content of about 60%, does not stick to the filter cloth and does not clog the filter cloth, the water quality is not sticky and easy to filter.

[0032] 3. The sludge stabilizer of this application can construct a sludge skeleton structure, and a hydration gelation reaction will occur during the later treatment process to form a rigid structure with a certain strength, so that the sludge cake has the characteristics of long-term stability and continuous reduction of subsequent moisture loss. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0035] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] The applicant of this invention is engaged in research on sludge drying technology. In practice, it has been found that sludge with an influent water content of approximately 85% is difficult to evaporate during the drying process due to the difficulty in breaking down the cell walls. Furthermore, the addition of flocculants and other agents by wastewater treatment plants during dewatering alters the sludge's properties, making it often a "viscous," semi-solid, semi-liquid state. This results in unstable and inefficient operation of the drying process. During the heat exchange drying process, the sludge emits varying degrees of unpleasant odors, affecting the production workshop and plant environment, posing environmental risks to enterprises. The presence of unpleasant odors in the dried sludge also disrupts the resource recycling and reuse industry.

[0037] The inventors of this application previously used a ferrous sulfate and hydrogen peroxide process for sludge dewatering pretreatment. They discovered that a large amount of foam was generated during the reaction of the sludge and chemicals in the conditioning tank, which could easily overflow and pollute the environment. Simultaneously, the high-pressure diaphragm plate and frame filter press dewatering system suffered from unstable operation, large fluctuations in the moisture content of the sludge cake, and severe adhesion to the filter cloth, preventing automatic detachment and unloading. This resulted in one person being unable to work normally, forcing another person to temporarily assist with manual unloading, leading to high workload for sludge handling staff.

[0038] The process of adding ferrous sulfate and hydrogen peroxide caused severe corrosion of the filter cloth in the high-pressure diaphragm plate and frame filter press. The filter cloth broke after only three months of use, resulting in sludge leakage from the system. The filtrate containing sludge was discharged into the sewage treatment plant, which increased the cost of sludge removal agents for sewage treatment.

[0039] The process involves adding ferrous sulfate and hydrogen peroxide. Ferrous sulfate is acidic and contains iron ions, while hydrogen peroxide is a strong oxidant. During the sludge dilution process with system filter press water circulation, the wastewater showed excessive iron ion levels, becoming turbid and concentrated. The pH value continuously dropped to around 3, becoming acidic. When pumped into the wastewater treatment plant, the system produced large, uncontrollable foaming, and secondly, caused membrane system blockage requiring frequent membrane washing. The excessively low pH increased wastewater conditioning costs and also inhibited the normal reproduction of anaerobic and biological bacteria in the wastewater treatment plant, significantly impacting the wastewater treatment system.

[0040] Due to the large amount of reagent added, the site occupies a large area for material storage and is quite messy, which also increases the workload for personnel adding the reagent.

[0041] In view of the problems existing in the sludge drying process, and in order to achieve "volume reduction, stabilization, harmlessness, and resource recovery" in sludge drying treatment, the inventors of this application propose a sludge stabilizer, a method for preparing the sludge stabilizer, and a method for treating sludge wastewater using the sludge stabilizer. The applicant of this invention will illustrate the proposed sludge stabilizer, its preparation method, and the method for treating sludge wastewater using the sludge stabilizer through specific embodiments.

[0042] The first aspect is the method for preparing sludge stabilizers and the sludge stabilizers obtained.

[0043] The sludge stabilizer is obtained by uniformly mixing the magnesium carbonate, calcium carbonate, aluminum sulfate, potassium carbonate, aluminum oxide, and calcium oxide according to the product composition ratio.

[0044] The sludge stabilizer comprises, by weight, 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts alumina, and 20 parts calcium oxide, with an error of ≤1% in the proportions of each component. For example, the proportions of magnesium carbonate can be 9-11, calcium carbonate 18-22, aluminum sulfate 9-11, potassium carbonate 18-22, alumina 18-22, and calcium oxide 18-22.

[0045] Secondly, sludge dewatering is carried out using sludge stabilizers, specifically as follows:

[0046] S1. Add the sludge stabilizer to the sludge and mix it thoroughly. The amount of sludge stabilizer added is 20% to 40% of the dry sludge weight.

[0047] S2. Add an organic dewatering agent to the sludge obtained in S1, so that the concentration of the organic dewatering agent in the sludge is 0.02% to 0.25%.

[0048] S3. The sludge obtained in step S2 is fed into a plate and frame filter press for dewatering.

[0049] In the specific implementation process, the organic dehydrating agent needs to be prepared, specifically as follows:

[0050] The mixture consists of 20 parts by mass fraction of dimethyl diallyl ammonium chloride, 30 parts by mass fraction of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass fraction of polyamine. The mixture is heated to 50°C and reacted for 30 minutes. After the reaction is completed, the material is dried, pulverized, and granulated to obtain a white powder with a bulk density of 600 kg / m3.

[0051] The prepared organic dehydrating agent powder was added to clean water at 15-30℃ and continuously stirred to dissolve it, thus dissolving the organic dehydrating agent powder into a 0.25%–0.50% storage aqueous solution.

[0052] The obtained storage aqueous solution is diluted online with 5 to 10 times the amount of water and then stored for later use, with a storage time not exceeding 24 hours.

[0053] The sludge in the following examples is derived from a random mixture of sludge from Ningxia Hongsipu Sewage Treatment Plant, Qingtongxia Sewage Treatment Plant, and the First, Second, and Third Sewage Treatment Plants, with a sludge moisture content of 85%.

[0054] The present invention will now be described through specific embodiments, as follows:

[0055] Example 1.1

[0056] Methods for preparing stabilizers and stabilizers

[0057] The sludge stabilizer is obtained by uniformly mixing 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide according to the product composition ratio.

[0058] Example 1.2

[0059] Preparation of diluted organic dehydrating agent solution:

[0060] 20 parts by mass of dimethyl diallyl ammonium chloride, 30 parts by mass of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass of polyamine were uniformly mixed and heated to 50°C for 30 minutes. After the reaction was completed, the material was dried, pulverized, and granulated to obtain a bulk density of 600 kg / m³. 3 White powder particles.

[0061] The organic dehydrating agent powder was added to clean water at 22-27°C and continuously stirred to dissolve, resulting in a 0.35% storage aqueous solution.

[0062] The resulting storage aqueous solution was diluted online with 8 times the amount of water and stored for later use, with a storage time not exceeding 24 hours.

[0063] Example 1.3

[0064] Sludge dewatering process:

[0065] Dehydration was carried out using the diluted organic dehydrating agent prepared in Example 1.2.

[0066] S1. Add 400 kg of sludge stabilizer to 12 tons of sludge with a moisture content of 85% and stir thoroughly. The amount of sludge stabilizer added is 22% of the dry sludge weight.

[0067] The sludge stabilizer is a mixture of 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide by mass fraction.

[0068] S2. The diluted organic dehydrating agent obtained in Example 1.2 is added to the sludge obtained in S1 using a metering screw pump. The amount of the effective component of the organic dehydrating agent added is 250 kg, so that the concentration of the solution is 0.25%.

[0069] S3. The sludge treated in step S2 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was found to be 60%, as detailed in Table 1. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed a salt content of 5655 mg / L, a conductivity of 8.09 mS / cm, a COD of 1156 mg / L, and an ammonia nitrogen of 190 mg / L. No iron was detected in the sludge, as detailed in Table 2.

[0070] Example 2.1

[0071] Methods for preparing stabilizers and stabilizers

[0072] The sludge stabilizer is obtained by uniformly mixing 9 parts magnesium carbonate, 18 parts calcium carbonate, 11 parts aluminum sulfate, 22 parts potassium carbonate, 22 parts aluminum oxide, and 18 parts calcium oxide according to the product composition ratio.

[0073] Example 2.2

[0074] Preparation of diluted organic dehydrating agent solution:

[0075] 20 parts by mass of dimethyl diallyl ammonium chloride, 30 parts by mass of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass of polyamine were uniformly mixed and heated to 50°C for 30 minutes. After the reaction was completed, the material was dried, pulverized, and granulated to obtain a bulk density of 600 kg / m³. 3 White powder particles.

[0076] The organic dehydrating agent powder is added to clean water at 15-22°C and continuously stirred to dissolve, resulting in a 0.25% storage aqueous solution.

[0077] The resulting storage aqueous solution was diluted online with 5 times the amount of water and stored for later use, with a storage time not exceeding 24 hours.

[0078] Example 2.3

[0079] Sludge dewatering process:

[0080] Dehydration was carried out using the diluted organic dehydrating agent prepared in Example 2.2.

[0081] S1. Add 720 kg of sludge stabilizer to 12 tons of sludge with a moisture content of 85% and stir thoroughly. The amount of sludge stabilizer added is 40% of the dry sludge weight.

[0082] The sludge stabilizer is a mixture of 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide by mass fraction.

[0083] S2. The diluted organic dewatering agent obtained in Example 2.2 is added to the sludge obtained in S1 using a metering screw pump. The amount of the effective component of the organic dewatering agent added is 250 kg, so that the concentration of the solution is 0.25%.

[0084] S3. The sludge treated in step S2 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was 62%, as shown in Table 1. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed a salt content of 5622 mg / L, a conductivity of 8.05 mS / cm, a COD of 1157 mg / L, and an ammonia nitrogen of 191 mg / L. No iron was detected in the sludge, as shown in Table 2.

[0085] Example 3.1

[0086] Methods for preparing stabilizers and stabilizers

[0087] The sludge stabilizer is obtained by uniformly mixing 11 parts magnesium carbonate, 22 parts calcium carbonate, 9 parts aluminum sulfate, 18 parts potassium carbonate, 18 parts aluminum oxide, and 22 parts calcium oxide according to the product composition ratio.

[0088] Example 3.2

[0089] Preparation of diluted organic dehydrating agent solution:

[0090] 20 parts by mass of dimethyl diallyl ammonium chloride, 30 parts by mass of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass of polyamine were uniformly mixed and heated to 50°C for 30 minutes. After the reaction was completed, the material was dried, pulverized, and granulated to obtain a bulk density of 600 kg / m³. 3 White powder particles.

[0091] The organic dehydrating agent powder is added to clean water at 27-30°C and continuously stirred to dissolve, resulting in a 0.5% storage aqueous solution.

[0092] The resulting storage aqueous solution was diluted online with 10 times the amount of water and stored for later use, with a storage time not exceeding 24 hours.

[0093] Example 3.3

[0094] Sludge dewatering process:

[0095] Dehydration was carried out using the diluted organic dehydrating agent prepared in Example 3.2.

[0096] S1. Add 720 kg of sludge stabilizer to 12 tons of sludge with a moisture content of 85% and stir thoroughly. The amount of sludge stabilizer added is 40% of the dry sludge weight.

[0097] The sludge stabilizer is a mixture of 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide by mass fraction.

[0098] S2. The diluted organic dehydrating agent obtained in Example 3.2 is added to the sludge obtained in S1 using a metering screw pump. The amount of the effective component of the organic dehydrating agent added is 250 kg, so that the concentration of the solution is 0.25%.

[0099] S3. The sludge treated in step S2 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was 61%, as shown in Table 1. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed a salt content of 5699 mg / L, a conductivity of 8.09 mS / cm, a COD of 1150 mg / L, and an ammonia nitrogen of 190 mg / L. No iron was detected in the sludge, as shown in Table 2.

[0100] Example 4.1

[0101] Methods for preparing stabilizers and stabilizers

[0102] The sludge stabilizer is obtained by uniformly mixing 10 parts magnesium carbonate, 19 parts calcium carbonate, 10 parts aluminum sulfate, 21 parts potassium carbonate, 19 parts aluminum oxide, and 21 parts calcium oxide according to the product composition ratio.

[0103] Example 4.2

[0104] Preparation of diluted organic dehydrating agent solution:

[0105] 20 parts by mass of dimethyl diallyl ammonium chloride, 30 parts by mass of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass of polyamine were uniformly mixed and heated to 50°C for 30 minutes. After the reaction was completed, the material was dried, pulverized, and granulated to obtain a bulk density of 600 kg / m³. 3 White powder particles.

[0106] The organic dehydrating agent powder was added to clean water at 22-27°C and continuously stirred to dissolve, resulting in a 0.35% storage aqueous solution.

[0107] The resulting storage aqueous solution was diluted online with 8 times the amount of water and stored for later use, with a storage time not exceeding 24 hours.

[0108] Example 4.3

[0109] Sludge dewatering process:

[0110] Dehydration was carried out using the diluted organic dehydrating agent prepared in Example 3.2.

[0111] S1. Add 400 kg of sludge stabilizer to 12 tons of sludge with a moisture content of 85% and stir thoroughly. The amount of sludge stabilizer added is 22% of the dry sludge weight.

[0112] The sludge stabilizer is a mixture of 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide by mass fraction.

[0113] S2. The diluted organic dehydrating agent obtained in Example 4.2 is added to the sludge obtained in S1 using a metering screw pump. The amount of the effective component of the organic dehydrating agent added is 200 kg, so that the concentration of the solution is 0.2%.

[0114] S3. The sludge treated in step S2 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was 62%, as shown in Table 1. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed a salt content of 5631 mg / L, a conductivity of 8.12 mS / cm, a COD of 1184 mg / L, and an ammonia nitrogen of 195 mg / L. No iron was detected in the sludge, as shown in Table 2.

[0115] Example 5.1

[0116] Methods for preparing stabilizers and stabilizers

[0117] The sludge stabilizer is obtained by uniformly mixing 10 parts magnesium carbonate, 21 parts calcium carbonate, 10 parts aluminum sulfate, 19 parts potassium carbonate, 21 parts aluminum oxide, and 19 parts calcium oxide according to the product composition ratio.

[0118] Example 5.2

[0119] Preparation of diluted organic dehydrating agent solution:

[0120] 20 parts by mass of dimethyl diallyl ammonium chloride, 30 parts by mass of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass of polyamine were uniformly mixed and heated to 50°C for 30 minutes. After the reaction was completed, the material was dried, pulverized, and granulated to obtain a bulk density of 600 kg / m³. 3 White powder particles.

[0121] The organic dehydrating agent powder was added to clean water at 22-27°C and continuously stirred to dissolve, resulting in a 0.35% storage aqueous solution.

[0122] The resulting storage aqueous solution was diluted online with 8 times the amount of water and stored for later use, with a storage time not exceeding 24 hours.

[0123] Example 5.3

[0124] Sludge dewatering process:

[0125] Dehydration was carried out using the diluted organic dehydrating agent prepared in Example 3.2.

[0126] S1. Add 400 kg of sludge stabilizer to 12 tons of sludge with a moisture content of 85% and stir thoroughly. The amount of sludge stabilizer added is 22% of the dry sludge weight.

[0127] The sludge stabilizer is a mixture of 10 parts magnesium carbonate, 20 parts calcium carbonate, 10 parts aluminum sulfate, 20 parts potassium carbonate, 20 parts aluminum oxide, and 20 parts calcium oxide by mass fraction.

[0128] S2. The diluted organic dehydrating agent obtained in Example 5.2 is added to the sludge obtained in S1 using a metering screw pump. The amount of the effective component of the organic dehydrating agent added is 23 kg, so that the concentration of the solution is 0.02%.

[0129] S3. The sludge treated in step S2 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was tested and found to be 68%. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed that the salt content was 5632 mg / L, the conductivity was 8.04 mS / cm, the COD value was 1152 mg / L, and the ammonia nitrogen value was 197 mg / L. No iron was detected in the sludge. See Table 2 for details.

[0130] Comparative Example 1.1

[0131] Preparation of diluted organic dehydrating agent solution:

[0132] 20 parts by mass of dimethyl diallyl ammonium chloride, 30 parts by mass of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts by mass of polyamine were uniformly mixed and heated to 50°C for 30 minutes. After the reaction was completed, the material was dried, pulverized, and granulated to obtain a bulk density of 600 kg / m³. 3 White powder particles.

[0133] The organic dehydrating agent powder was added to clean water at 22-27°C and continuously stirred to dissolve, resulting in a 0.35% storage aqueous solution.

[0134] The resulting storage aqueous solution was diluted online with 8 times the amount of water and stored for later use, with a storage time not exceeding 24 hours.

[0135] Comparative Example 1.2

[0136] Sludge dewatering process:

[0137] Dehydration process using organic dehydrating agents

[0138] S1. The diluted organic dewatering agent obtained in Comparative Example 1.1 was added to 12 tons of sludge with a water content of 85% using a metering screw pump. The amount of effective component of the organic dewatering agent added was 250 kg, so that the concentration of the solution was 0.25%.

[0139] S2. The sludge treated in step S1 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was tested and found to be 68%, as detailed in Table 1. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed a salt content of 12640 mg / L, a conductivity of 9.0 mS / cm, a COD value of 4276 mg / L, an ammonia nitrogen value of 506 mg / L, and an iron content of 24.2 mg / L, as detailed in Table 2.

[0140] Comparative Example 2

[0141] Ferrous sulfate + hydrogen peroxide dehydration process

[0142] S1. Add 550 kg of ferrous sulfate to 8 tons of sludge with a moisture content of 85% and mix thoroughly.

[0143] S2. Add 400 kg of hydrogen peroxide to the sludge obtained in S1 and mix the hydrogen peroxide and sludge thoroughly.

[0144] S3. The sludge treated in step S2 was fed into a plate and frame filter press for filtration. The moisture content of the filter cake was tested and found to be 62%, as detailed in Table 1. The chemical composition of the filtrate after sludge dewatering was also tested. The results showed a salt content of 25902 mg / L, a conductivity of 13.53 mS / cm, a COD value of 2956 mg / L, an ammonia nitrogen value of 891 mg / L, and an iron content of 3218 mg / L, as detailed in Table 2.

[0145] Table 1 Comparison of dehydration effects of various examples and comparative examples

[0146]

[0147] Table 2 shows the chemical composition of the pressure filter water after sludge dewatering in the examples.

[0148]

[0149] As can be seen from Examples 1.3 and Comparative Examples 1.2 and 2, when treating sludge with a moisture content of 85%, the method of Example 1 is more cost-effective and has higher dewatering efficiency. Furthermore, the chemical composition of the sludge dewatered by the method of Example 1 is free of iron, and the salt content, conductivity, COD value, and ammonia nitrogen value are much lower than those of the methods of Examples 1.2 and 2.

[0150] Comparative Example 1.2, compared to Example 1, did not contain a stabilizer, resulting in lower dehydration efficiency and higher levels of salt, conductivity, COD, and ammonia nitrogen in the filtered water.

[0151] Therefore, it can be seen that the dehydrating agents and dehydration methods used in this application have lower dehydration costs, higher dehydration efficiency, and are more environmentally friendly.

[0152] The stabilizer provided in this application enhances the pressing effect during the plate and frame dewatering stage. When applied to sludge, it disrupts some colloidal particles and the molecular structure of the original polyacrylamide in the sludge, reducing sludge viscosity. The original polyacrylamide in the sludge originates from polyacrylamide flocculants left over from wastewater treatment processes. It stabilizes the properties of sludge with complex origins. Within the plate and frame dewatering system, it acts as a framework, increasing filtration channels for sludge dewatering. It disrupts sludge cell walls, facilitating the removal of intracellular and extracellular free water. It removes some of the odor produced by adsorbed sludge without altering the quality of the filtered water.

[0153] 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sludge dewatering process, characterized in that, A sludge stabilizer is adopted, which comprises, in parts by mass, 10 parts of magnesium carbonate, 20 parts of calcium carbonate, 10 parts of aluminum sulfate, 20 parts of potassium carbonate, 20 parts of aluminum oxide, and 20 parts of calcium oxide, with an error of less than 1% for each component; The sludge dewatering process comprises the following steps: S1, the sludge stabilizer is added to the sludge and fully stirred, and the addition amount of the sludge stabilizer is 20% to 40% of the absolute dry mud amount; S2, an organic dewatering agent is added to the sludge obtained in S1, so that the concentration of the organic dewatering agent in the sludge is 0.02% to 0.25%; the organic dewatering agent comprises, in mass fraction, 20 parts of dimethyl diallyl ammonium chloride, 30 parts of acryloyloxyethyl trimethyl ammonium chloride, and 50 parts of polyamine; S3, the sludge obtained in step S2 is fed into a plate and frame filter press for pressure filtration and dewatering treatment.

2. The sludge dewatering process of claim 1, wherein, The configuration method of the organic dewatering agent before being added to the sludge is as follows: the organic dewatering agent powder particles are added to clean water at 15-30℃, and continuously stirred and dissolved, so that the organic dewatering agent powder particles are dissolved into a 0.25% to 0.50% storage aqueous solution.

3. The sludge dewatering process of claim 2, wherein, Before being added to the sludge, the storage aqueous solution is diluted by 5 to 10 times of water on line.

4. The sludge dewatering process of claim 1, wherein, The device for adding the organic dewatering agent to the sludge is a volumetric dosing pump.

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