A sludge deep dewatering combined conditioner and a sludge deep dewatering combined conditioning method

Abstract

This invention relates to a combined conditioner and method for deep sludge dewatering. The combined conditioner comprises cationic surfactants, anionic surfactants, coagulants, and flocculants. By combining cationic and anionic surfactants, the conditioner optimizes the solubilizing and dispersing properties of the surfactants, significantly improving their ability to dissolve extracellular polymers in sludge and enhancing the release of bound water. Furthermore, by combining the coagulant and flocculant, the charge neutralization effect is enhanced, increasing the size and strength of the sludge flocs. This invention solves the problems of low sludge dewatering efficiency in current urban wastewater treatment plants and the increased volume of dewatered sludge caused by the addition of large amounts of lime, fly ash, and other materials during sludge dewatering. It improves the efficiency of deep sludge dewatering, is simple to use, does not generate secondary pollution, and significantly reduces the subsequent treatment costs of sludge, providing a new method for deep sludge dewatering.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, specifically to a combined conditioner and method for deep sludge dewatering. Background Technology

[0003] Current methods for sludge dewatering in municipal wastewater treatment plants primarily rely on mechanical dewatering equipment, such as belt filter presses, plate and frame filter presses, and centrifugal dewatering machines. Due to the hydrophilicity of extracellular polymers in sludge, the sludge has a high specific resistance, making direct mechanical dewatering ineffective. Therefore, sludge conditioning is necessary before dewatering to improve its dewatering performance. The most common sludge conditioning method involves chemical agents. Currently, wastewater treatment plants often use only a single coagulant for sludge conditioning, with unsatisfactory results. Even after conditioning and dewatering, the sludge still has a moisture content as high as 70%–80%, failing to meet the sludge disposal access requirement of a moisture content of 60% or less. Further reduction in moisture content is needed. To this end, current projects often employ drying and incineration processes to further reduce moisture content. However, these processes have significant drawbacks, including complex operation and management, high investment and maintenance costs, and secondary pollution during treatment.

[0004] To address the aforementioned issues, the research and development of advanced sludge dewatering technology based on enhanced sludge conditioning has become a hot topic. The development of advanced sludge dewatering technology will provide an efficient and low-cost path for sludge to meet the sludge disposal access requirements. Existing sludge deep dewatering and conditioning technologies primarily rely on adding skeleton materials such as quicklime, red mud, and fly ash to enhance sludge floc strength and reduce compressibility, thereby promoting sludge dewatering and significantly reducing sludge moisture content. However, the large quantities of quicklime, red mud, and fly ash added pose a significant problem of sludge volume expansion during dewatering. Another type of sludge deep dewatering and conditioning technology uses oxidants to break down extracellular polymers in the sludge, releasing bound water. However, oxidants usually need to be used in combination with other agents. For example, while persulfate advanced oxidation technology has a high free radical formation rate, it requires the use of transition metal ions to activate persulfate, which can easily introduce metal ions into the sludge system, causing secondary pollution and hindering subsequent sludge treatment and disposal. Furthermore, some oxidants are more effective under acidic conditions, which can corrode equipment, increasing sludge treatment costs and complicating operation and management. Therefore, developing a highly efficient, low-cost, and environmentally friendly sludge deep dewatering and conditioning technology is urgently needed. Summary of the Invention

[0005] The purpose of this invention is to provide a combined conditioner and method for deep dewatering of sludge, so as to solve the problems of low conditioning efficiency and high water content of dewatered sludge in existing sludge agents, and also to solve the problems of sludge volume increase, equipment corrosion and secondary pollution that are easily caused by existing deep dewatering methods.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A combined conditioner for deep dewatering of sludge, comprising cationic surfactants, anionic surfactants, coagulants, and flocculants.

[0008] Based on the aforementioned technical means, the synergistic effect of cationic and anionic surfactants can improve the performance of a single surfactant, effectively enhancing the dissolution of extracellular polymers in sludge and releasing a large amount of bound water. The combination of coagulants and flocculants can significantly reduce the electrostatic repulsion between sludge particles through charge neutralization and adsorption bridging, promoting the formation of larger and stronger sludge flocs and further improving sludge dewatering efficiency. This combined conditioner is suitable for deep dewatering of sludge of different types. The dosage of each agent can be adjusted according to the sludge's organic matter content, zeta potential, and other sludge characteristics, achieving efficient deep dewatering, significantly reducing sludge volume, and lowering subsequent treatment costs. Furthermore, this combined conditioner does not require pH adjustment, avoiding equipment corrosion. Compared to advanced oxidation processes, the sludge dewatering conditioner used in this invention is cheaper, easier to transport and store, and simpler to add and use. In addition, the surfactants, coagulants, and flocculants used in this combined conditioner have minimal environmental impact, contributing to the greening of sludge treatment.

[0009] Preferably, the sludge deep dewatering combined conditioner is composed of 100-300 mg / gDS cationic surfactant, 10-30 mg / gDS anionic surfactant, 40-80 mg / gDS coagulant and 3-5 mg / gDS flocculant.

[0010] Preferably, the cationic surfactant is selected from quaternary ammonium salt cationic surfactants.

[0011] Preferably, the anionic surfactant is selected from sodium dodecylbenzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS).

[0012] Preferably, the coagulant is selected from inorganic polymeric coagulants.

[0013] Preferably, the flocculant is selected from organic polymeric flocculants.

[0014] Preferably, the quaternary ammonium salt cationic surfactant is selected from one of hexadecyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium bromide (DTAB), and dodecyltrimethylammonium chloride (DTAC).

[0015] Preferably, the inorganic coagulant is selected from polyaluminum chloride (PAC) and polyferric sulfate (PFS).

[0016] Preferably, the organic flocculant is selected from cationic polyacrylamide (cPAM) and polydimethyldiallylammonium chloride (PDMDAAC).

[0017] Preferably, the mass ratio of the cationic surfactant to the anionic surfactant is 10:1 to 15:1.

[0018] The present invention also provides a method for sludge conditioning and dewatering using a sludge deep dewatering combination conditioner as described in the present invention, comprising the following steps:

[0019] S1. Add cationic and anionic surfactants to the sludge to be treated and stir thoroughly to react;

[0020] S2. Add coagulant to the sludge to be treated, stir quickly to react and mix thoroughly; then add flocculant, stir slowly to react, let stand, and obtain conditioned sludge.

[0021] S3. Press the conditioned sludge to obtain filtrate and sludge cake.

[0022] The sludge deep dewatering combined conditioning method of the present invention, by employing the sludge dewatering combined conditioning agent and treatment steps of the present invention, can significantly reduce the water content in the sludge, reducing it from 97%-99% to below 60%, thus achieving deep dewatering of the sludge. By adding different conditioning agents in stages and carrying out a stirring reaction, followed by mechanical filtration, the entire process is simple to operate, easy to control and implement. After dewatering, the filtrate and sludge cake can be recovered, and the sludge cake can be subsequently treated and utilized for resource recovery. The volume of the sludge after deep dewatering is significantly reduced, facilitating transportation and disposal, and reducing the environmental impact of the sludge. The present invention is applicable to the treatment of sludge with different sludge characteristics and has a wide range of applications.

[0023] Preferably, in step S1, when the organic matter content (VSS / TSS) in the sludge to be treated is ≤50%, the dosage of cationic surfactant is 100-200 mg / gDS, and the dosage of anionic surfactant is 10-20 mg / gDS; when the organic matter content (VSS / TSS) in the sludge to be treated is ≥50%, the dosage of cationic surfactant is 200-300 mg / gDS, and the dosage of anionic surfactant is 20-30 mg / gDS.

[0024] VSS / TSS represents the ratio of volatile suspended solids to total suspended solids. VSS, or volatile suspended solids, refers to the portion of organic matter that can burn and volatilize at a certain temperature (usually 550 degrees Celsius). TSS, or total suspended solids, refers to the total amount of solid matter suspended in water, including both organic and inorganic matter. A higher VSS / TSS ratio indicates a higher content of organic matter in the suspended solids.

[0025] Experimental studies have shown that the dosage of cationic surfactants is significantly correlated with the organic matter content of sludge. For different types of sludge, the dosage of cationic surfactants can be determined by the formula: 4.593 × (MLVSS / MLSS) - 34.229 (R). 2 =0.974) was estimated, and the dosage of cationic and anionic surfactants was further determined through experiments. Controlling the dosage of surfactants ensures the targeted and effective treatment results. Less surfactant is needed when the organic matter content is low, saving costs; conversely, the dosage is increased when the organic matter content is high, ensuring treatment efficiency. By adjusting the dosage of surfactants, the sludge treatment process can be better controlled, improving the stability and reliability of sludge treatment.

[0026] MLVSS / MLSS represents the ratio of volatile suspended solids to total suspended solids in the mixed liquor. MLVSS refers to the volatile suspended solids portion of the mixed liquor, mainly composed of microorganisms, while MLSS refers to the total suspended solids content, including microorganisms and non-volatile inorganic matter. The MLVSS / MLSS ratio can be used to estimate the microbial content in activated sludge and is commonly used in wastewater treatment processes to assess the biological activity of sludge.

[0027] Preferably, in step S1, when the sludge zeta potential value is below -15mV, the coagulant dosage is 60-80 mg / gDS and the flocculant dosage is 4-5 mg / gDS; when the sludge zeta potential value is above -15mV, the coagulant dosage is 40-60 mg / gDS and the flocculant dosage is 3-4 mg / gDS.

[0028] Experimental studies have shown a negative correlation between the initial zeta potential of sludge and the dosage of coagulants and flocculants; that is, the lower the initial zeta potential of the sludge, the more coagulants and flocculants are required. When the sludge zeta potential is below -15mV, controlling the dosage of coagulants and flocculants can effectively promote sludge flocculation while reducing unnecessary chemical use. When the sludge zeta potential is above -15mV, appropriately reducing the dosage of coagulants and flocculants can save costs and reduce the environmental impact of chemicals. It also avoids excessive positively charged coagulants causing the sludge surface to re-charge positively, thus generating electrostatic repulsion and affecting the flocculation effect. This flexible dosage adjustment strategy reflects the economic and environmental benefits of the treatment process.

[0029] Preferably, in step S1, the solid content of the sludge to be treated is between 10 g / L and 30 g / L.

[0030] By controlling the solids content of the conditioned sludge, the stability and efficiency of the sludge dewatering process can be ensured. A higher solids content in the conditioned sludge means a greater weight of sludge per volume, thus reducing the amount of sludge transported and processed, saving on dewatering costs. However, excessively high solids content leads to a thicker sludge cake during dewatering, prolonging the time for water removal and potentially causing equipment blockage and difficulty in cleaning. Controlling the solids content of the conditioned sludge helps improve the operating efficiency of sludge dewatering equipment, achieve better dewatering results, reduce the difficulty of subsequent processing, and extend the equipment's lifespan.

[0031] Preferably, in step S2, a coagulant solution is added, wherein the mass concentration of the coagulant in the coagulant solution is 5% to 10%.

[0032] Preferably, in step S2, the added flocculant is cationic polyacrylamide with a molecular weight greater than 3 million, and when a cationic polyacrylamide solution is added, the mass concentration of cationic polyacrylamide in the cationic polyacrylamide solution is 0.1% to 0.4%.

[0033] The added flocculant is cationic polyacrylamide with a molecular weight greater than 3 million. High molecular weight polyacrylamide has strong adsorption and bridging capabilities, effectively capturing suspended particles and promoting flocculation. Cationic polyacrylamide carries a positive charge, which can neutralize the negatively charged suspended particles, enhancing the flocculation effect. High molecular weight cationic polyacrylamide is not easily soluble in water, so preparing a low-concentration solution of 0.1%–0.4% is convenient.

[0034] Preferably, in step S2, the added flocculant is polydimethyl diallyl ammonium chloride with a molecular weight greater than 10 million, and when the polydimethyl diallyl ammonium chloride solution is added, the mass concentration of polydimethyl diallyl ammonium chloride in the polydimethyl diallyl ammonium chloride solution does not exceed 20%.

[0035] Polydimethyl diallyl ammonium chloride (PDMC) with a molecular weight greater than 10 million possesses strong bridging capabilities and a high positive charge density, effectively reducing electrostatic repulsion between particles and agglomerating suspended particles into larger flocs, thereby accelerating the sedimentation process. Furthermore, due to the large molecular weight of PDMC, excessively high solution concentrations can lead to high viscosity, making it difficult to add. Therefore, the mass concentration of PDMC is controlled to not exceed 20%.

[0036] Preferably, in step S2, the rapid stirring speed is 300 r / min, and the reaction time is 10 to 20 min.

[0037] Preferably, in step S2, the stirring speed is 60 r / min and the reaction time is 10 to 20 min.

[0038] Preferably, in step S2, the settling time is 10 to 30 minutes.

[0039] Preferably, a plate and frame filter press is used to mechanically filter the conditioned sludge. The filter cloth of the plate and frame filter press is made of polypropylene long fiber with good acid and alkali resistance, and the strength of the filter cloth is enhanced by twill weave. The filter plates of the plate and frame filter press are provided with filter cavities on both sides. Flat cylindrical protruding particles are densely distributed on the bottom surface of the filter cavity. The protruding particles are evenly distributed in a spiral shape radiating outward from the central through hole of the filter plate.

[0040] The beneficial effects of this invention are:

[0041] This invention presents a combined sludge dewatering and conditioning method. The combined sludge conditioner is highly efficient, low-cost, and simple to use, enabling deep dewatering of sludge of varying qualities. It solves the problems of sludge volume expansion and secondary pollution associated with current deep sludge dewatering and conditioning technologies. This invention effectively achieves a synergistic effect by combining anionic and cationic surfactants, as well as inorganic coagulants and organic flocculants, significantly improving the efficiency of existing sludge conditioning methods using single surfactants and coagulants. This combined conditioner, used for deep sludge dewatering, effectively promotes the release of bound water from the sludge. Furthermore, it works effectively over a wide pH range without the need for pre-adjustment, avoiding the need for acidic environments, thus preventing equipment corrosion, reducing filter cloth clogging, extending equipment lifespan, and minimizing secondary pollution and environmental impact, contributing to the greening of sludge treatment. In addition, the sludge dewatering conditioner is primarily organic, increasing the calorific value of the sludge and facilitating incineration. This sludge dewatering conditioner is suitable for sludge with different properties and has good adaptability. When used for deep sludge dewatering, it significantly improves dewatering efficiency and reduces sludge volume without causing sludge bulking; it also greatly reduces the cost of subsequent sludge treatment and disposal, resulting in significant economic benefits.

[0042] The sludge deep dewatering and conditioning method of this invention, through the use of the sludge dewatering conditioner combination and treatment steps of this invention, can significantly reduce the water content in sludge, reducing the water content in the sludge to be treated from over 98% to less than 60% in the sludge cake, thus achieving deep dewatering of sludge. The sludge dewatering conditioner combination of this invention, after being added to the sludge, dissolves completely without increasing the sludge volume. The volume of the dewatered sludge is reduced by more than 90%, greatly reducing the transportation and subsequent disposal costs of the sludge. Furthermore, the sludge dewatering conditioner has good flocculation effect, low viscosity, and good sludge cake detachment during sludge unloading, making it less likely to stick to the filter cloth, and sludge cake collection and filter cloth cleaning are relatively convenient. By adding different conditioning agents in stages and stirring the reaction, followed by mechanical pressure filtration, the entire process is simple to operate, easy to control and implement. During the dewatering process, filtrate and sludge cake can be recovered. The filtrate can be further treated or reused, and the sludge cake can be used as a resource for subsequent treatment or utilization, improving resource utilization efficiency. The volume of sludge after deep dewatering is significantly reduced, facilitating transportation and disposal, and lowering the cost and environmental impact of sludge treatment. Because the sludge to be treated has a very high moisture content, this invention is applicable to the treatment of various types of sludge with high moisture content, has a wide range of applications, and has significant potential for widespread application in the field of sludge treatment technology. Detailed Implementation

[0043] The following description, with reference to preferred embodiments, illustrates the implementation of the present invention. Those skilled in the art can clearly understand other advantages and effects of the present invention from the content set forth in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are merely illustrative of the present invention and not intended to limit the scope of protection of the present invention.

[0044] Example 1

[0045] A sludge deep dewatering combined conditioner is composed of 150 mg / gDS of hexadecyltrimethylammonium bromide, 15 mg / gDS of sodium dodecyl sulfate, 60 mg / gDS of polyaluminum chloride and 3.5 mg / gDS of cationic polyacrylamide.

[0046] The method of conditioning and dewatering sludge using the above-mentioned combined sludge dewatering conditioner...

[0047] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.35% cationic polyacrylamide solution.

[0048] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 16.70 g / L, and the single treatment volume was 1200 L, so the total solids content was 20040 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 38.58 ± 0.30%, the water content was 98.33%, the zeta potential was -8.60 mV, the pH value was 7.07, the TN concentration was 3.30 mg / L, the TP concentration was 0.82 mg / L, and the SCOD concentration was 74.525 mg / L.

[0049] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 150 mg / gDS of cationic surfactant cetyltrimethylammonium bromide and 15 mg / gDS of anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 30 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0050] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage, and stir continuously while adding the chemicals. Add 60 mg / gDS inorganic coagulant polyaluminum chloride to the sludge. After the addition is complete, stir rapidly at 300 r / min for 10 minutes. Then add 3.5 mg / gDS organic flocculant cationic polyacrylamide. After the addition is complete, stir slowly at 60 r / min for 10 minutes and let stand for 10 minutes to obtain conditioned sludge.

[0051] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0052] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0053] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 7.11, the TN concentration was 1.65 mg / L, the TP concentration was 0.20 mg / L, and the SCOD concentration was 20.370 mg / L. The moisture content of the mud cake was 48.98%.

[0054] Example 2

[0055] A sludge deep dewatering combined conditioner is composed of 100 mg / gDS of hexadecyltrimethylammonium chloride, 10 mg / gDS of sodium dodecyl sulfate, 40 mg / gDS of polyferric sulfate and 3 mg / gDS of cationic polyacrylamide.

[0056] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0057] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.2% cationic polyacrylamide solution.

[0058] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 28.05 g / L, and the single treatment volume was 1200 L, so the total solids content was 33660 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 33.28 ± 0.67%, the water content was 97.16%, the zeta potential was -6.92 mV, the pH value was 7.06, and the SCOD concentration was 84.521 mg / L.

[0059] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 100 mg / gDS cationic surfactant cetyltrimethylammonium chloride and 10 mg / gDS anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 15 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0060] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. Stir continuously while adding the chemicals. Add 40 mg / gDS inorganic coagulant polyferric sulfate to the sludge. After the addition is complete, stir rapidly at 300 r / min for 10 minutes. Then add 3 mg / gDS organic flocculant cationic polyacrylamide. After the addition is complete, stir slowly at 60 r / min for 10 minutes. Let stand for 20 minutes to obtain conditioned sludge.

[0061] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0062] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0063] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 7.15, the SCOD concentration in the filtrate was 29.297 mg / L, and the moisture content of the mud cake was 52.78%.

[0064] Example 3

[0065] A sludge deep dewatering combined conditioner is composed of 100 mg / gDS of dodecyltrimethylammonium chloride, 10 mg / gDS of sodium dodecyl sulfate, 40 mg / gDS of polyferric sulfate and 3 mg / gDS of cationic polyacrylamide.

[0066] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0067] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.2% cationic polyacrylamide solution.

[0068] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 26.78 g / L, and the single treatment volume was 1200 L, so the total solids content was 32136 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 33.08 ± 0.15%, the water content was 97.32%, the zeta potential was -7.33 mV, the pH value was 6.99, and the SCOD concentration was 81.065 mg / L.

[0069] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 100 mg / gDS cationic surfactant dodecyltrimethylammonium chloride and 10 mg / gDS anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 15 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0070] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. Stir continuously while adding the chemicals. Add 40 mg / gDS inorganic coagulant polyferric sulfate to the sludge. After the addition is complete, stir rapidly at 300 r / min for 10 minutes. Then add 3 mg / gDS organic flocculant cationic polyacrylamide. After the addition is complete, stir slowly at 60 r / min for 10 minutes. Let stand for 20 minutes to obtain conditioned sludge.

[0071] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0072] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0073] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 6.95, the SCOD concentration in the filtrate was 27.552 mg / L, and the moisture content of the mud cake was 56.52%.

[0074] Example 4

[0075] A sludge deep dewatering combined conditioner is composed of 200 mg / gDS of dodecyltrimethylammonium bromide, 20 mg / gDS of sodium dodecylbenzenesulfonate, 60 mg / gDS of polyaluminum chloride, and 4 mg / gDS of cationic polydimethyldiallylammonium chloride.

[0076] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0077] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 10 wt% cationic polyacrylamide solution.

[0078] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 21.77 g / L, and the single treatment volume was 1200 L, so the total solids content was 26124 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 48.52 ± 0.77%, the water content was 97.82%, the zeta potential was -10.90 mV, the pH value was 7.07, and the SCOD concentration was 41.06 mg / L.

[0079] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 200 mg / gDS cationic surfactant dodecyltrimethylammonium bromide and 20 mg / gDS anionic surfactant sodium dodecylbenzenesulfonate to the sludge to be treated at the same time, and stir rapidly at 300 r / min for 20 minutes to make the surfactant completely mixed and fully reacted.

[0080] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. While adding the chemicals, stir continuously. Add 60 mg / gDS inorganic coagulant polyaluminum chloride to the sludge. After the addition is complete, stir rapidly at 300 r / min for 15 minutes. Then add 4 mg / gDS organic flocculant cationic polydimethyldiallylammonium chloride. After the addition is complete, stir slowly at 60 r / min for 15 minutes. Let stand for 20 minutes to obtain conditioned sludge.

[0081] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0082] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0083] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 7.17, the SCOD concentration in the filtrate was 22.316 mg / L, and the water content of the mud cake was 57.28%.

[0084] Example 5

[0085] A sludge deep dewatering combined conditioner is composed of 300 mg / gDS of hexadecyltrimethylammonium bromide, 30 mg / gDS of sodium dodecyl sulfate, 80 mg / gDS of polyferric sulfate and 5 mg / gDS of cationic polyacrylamide.

[0086] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0087] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.2% cationic polyacrylamide solution.

[0088] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content (TS) of the sludge to be treated was 18.97 g / L, and the single treatment volume was 1200 L, so the total solids content was 22764 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 75.68 ± 0.44%, the water content was 98.10%, the zeta potential was -18.90 mV, the pH value was 7.10, and the SCOD concentration was 53.26 mg / L.

[0089] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 300 mg / gDS cationic surfactant cetyltrimethylammonium bromide and 30 mg / gDS anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 20 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0090] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. Stir continuously while adding the chemicals. Add 80 mg / gDS inorganic coagulant polyferric sulfate to the sludge. After the addition is complete, stir rapidly at 300 r / min for 15 minutes. Then add 5 mg / gDS organic flocculant cationic polyacrylamide. After the addition is complete, stir slowly at 60 r / min for 15 minutes. Let stand for 20 minutes to obtain conditioned sludge.

[0091] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0092] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0093] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 7.20, the SCOD concentration in the filtrate was 19.11 mg / L, and the moisture content of the mud cake was 51.78%.

[0094] Example 6

[0095] A sludge deep dewatering combined conditioner is composed of 300 mg / gDS of hexadecyltrimethylammonium chloride, 30 mg / gDS of sodium dodecylbenzenesulfonate, 80 mg / gDS of polyferric sulfate and 5 mg / gDS of cationic polydimethyldiallylammonium chloride.

[0096] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0097] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.35% cationic polyacrylamide solution.

[0098] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 19.15 g / L, and the single treatment volume was 1200 L, so the total solids content was 22980 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 77.25 ± 0.44%, the water content was 98.09%, the zeta potential was -17.99 mV, the pH value was 7.12, and the SCOD concentration was 51.77 mg / L.

[0099] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 300 mg / gDS cationic surfactant cetyltrimethylammonium chloride and 30 mg / gDS anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 20 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0100] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. While adding the chemicals, stir continuously. Add 80 mg / gDS inorganic coagulant polyferric sulfate to the sludge. After the addition is complete, stir rapidly at 300 r / min for 15 minutes. Then add 5 mg / gDS organic flocculant cationic polydimethyldiallylammonium chloride. After the addition is complete, stir slowly at 60 r / min for 15 minutes. Let stand for 20 minutes to obtain conditioned sludge.

[0101] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0102] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0103] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 7.18, the SCOD concentration in the filtrate was 16.091 mg / L, and the moisture content of the mud cake was 52.11%.

[0104] Example 7

[0105] A sludge deep dewatering combined conditioner is composed of 250 mg / gDS of hexadecyltrimethylammonium chloride, 20 mg / gDS of sodium dodecyl sulfate, 60 mg / gDS of polyaluminum chloride and 4 mg / gDS of cationic polyacrylamide.

[0106] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0107] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.35% cationic polyacrylamide solution.

[0108] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 14.50 g / L, and the single treatment volume was 1200 L, so the total solids content was 17400 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 60.68 ± 0.24%, the water content was 98.55%, the zeta potential was -12.90 mV, the pH value was 7.02, the TN concentration was 2.59 mg / L, and the TP concentration was 1.06 mg / L.

[0109] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 250 mg / gDS cationic surfactant cetyltrimethylammonium chloride and 20 mg / gDS anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 30 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0110] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. Stir continuously while adding the chemicals. Add 60 mg / gDS inorganic coagulant polyaluminum chloride to the sludge. After the addition is complete, stir rapidly at 300 r / min for 15 minutes. Then add 4 mg / gDS organic flocculant cationic polyacrylamide. After the addition is complete, stir slowly at 60 r / min for 15 minutes. Let stand for 20 minutes to obtain conditioned sludge.

[0111] S4. Sludge dewatering: The conditioned sludge is fed into a plate and frame filter press by a screw pump for mechanical filtration. The maximum sludge inlet pressure of the screw pump is 0.6 MPa, the secondary pressing pressure is 1.2 MPa, and the pressing time is 1 hour to obtain dewatered sludge.

[0112] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0113] The mud cake and filtrate obtained from the experiment were tested. The pH value of the filtrate was 6.98, the TN concentration was 2.23 mg / L, the TP concentration was 0.29 mg / L, and the SCOD concentration was 15.288 mg / L. The moisture content of the mud cake was 50.20%.

[0114] Example 8

[0115] A sludge deep dewatering combined conditioner is composed of 250 mg / gDS of hexadecyltrimethylammonium bromide, 20 mg / gDS of sodium dodecyl sulfate, 80 mg / gDS of polyaluminum chloride and 5 mg / gDS of cationic polyacrylamide.

[0116] The method for conditioning and dewatering sludge using the above-mentioned deep sludge dewatering combination conditioner includes the following steps:

[0117] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.1% cationic polyacrylamide solution.

[0118] The basic properties of the sludge to be treated were tested, and the total solids content of the sludge was calculated. The total solids content of the sludge to be treated was 18.97 g / L, and the single treatment volume was 100 ml, so the total solids content was 1.897 g. The dosage of each reagent component was calculated. Among them, the organic matter content (VSS / TSS) of the sludge to be treated was 57.24 ± 0.20%, the water content was 98.10%, the zeta potential was -17.49 mV, the pH value was 7.09, and the SCOD concentration was 41.20 mg / L.

[0119] S2. Add surfactant: Weigh the surfactant and add it to the sludge to be treated. Add 250 mg / gDS cationic surfactant cetyltrimethylammonium bromide and 20 mg / gDS anionic surfactant sodium dodecyl sulfate to the sludge to be treated. Stir rapidly at 300 r / min for 10 minutes to ensure that the surfactant is completely mixed and reacts fully.

[0120] S3. Adding coagulants and flocculants: Use a metering pump to precisely control the dosage. Stir continuously while adding the chemicals. Add 80 mg / gDS inorganic coagulant polyaluminum chloride to the initial treated sludge. After the addition is complete, stir rapidly at 300 r / min for 5 minutes. Then add 5 mg / gDS organic flocculant cationic polyacrylamide. After the addition is complete, stir slowly at 60 r / min for 10 minutes. Let stand for 20 minutes to obtain the conditioned sludge.

[0121] S4. Sludge dewatering: Pour the conditioned sludge into a precision positive pressure filter and filter for 15 minutes under a pressure of 0.4MPa.

[0122] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0123] Comparative Example 1

[0124] A method for deep dewatering and conditioning of sludge includes the following steps:

[0125] S1. Preparation: Prepare a 10% polyaluminum chloride solution and a 0.2% cationic polyacrylamide solution.

[0126] The basic properties of the sludge to be treated are the same as in Example 8. Seven sets of reactors were used for parallel comparative experiments. The formulation and dosage of the conditioner in each set are shown in Table 1. In Table 1, CTAB is hexadecyltrimethylammonium bromide, SDS is sodium dodecyl sulfate, PAC is polyaluminum chloride, and cPAM is cationic polyacrylamide.

[0127] Table 1. Composition and dosage of conditioning agents for each group

[0128]

[0129] S2. Add surfactant: Weigh and add surfactants. Add cationic surfactants to groups 1 and 5, and add anionic surfactants to groups 2 and 5. Stir rapidly at 300 r / min for 10 minutes to ensure complete mixing and full reaction.

[0130] S3. Add coagulant and flocculant: Add polyaluminum chloride to groups 3 and 6 and stir rapidly at 300 r / min for 5 minutes; then add cationic polyacrylamide to groups 4 and 6 and stir slowly at 60 r / min for 10 minutes. After conditioning, let each group stand for 20 minutes to obtain conditioned sludge.

[0131] S4. Sludge dewatering: Pour the raw sludge and the conditioned sludge into a precision positive pressure filter and filter for 15 minutes under a pressure of 0.4MPa.

[0132] S5. Depressurization and discharge: Recover the discharged filtrate and the sludge cake formed by pressure filtration.

[0133] The moisture content of the mud cakes obtained in Examples 1-8 and Control Example 1 were measured respectively, and the results are shown in Table 2.

[0134] Table 2 Filter cake moisture content results

[0135]

[0136] Table 2 shows that the combination of anionic and cationic surfactants, as well as the combination of coagulants and flocculants, produced a synergistic effect in sludge conditioning. Adding a small amount of anionic surfactant to cationic surfactants enhances their ability to dissolve extracellular polymers in sludge, further releasing water trapped within these polymers. Meanwhile, the combined use of coagulants and flocculants can combine functions such as double-layer compression and adsorption bridging, reducing electrostatic repulsion between sludge particles and promoting the formation of stronger floc structures. Therefore, the combined conditioning agents are more effective than the individual agents used alone.

[0137] In summary, the sludge deep dewatering combined conditioning method of the present invention, through the use of the sludge deep dewatering combined conditioning agent and treatment method steps of the present invention, can reduce the sludge moisture content to below 60%, achieving deep dewatering of the sludge. The sludge deep dewatering combined conditioning agent of the present invention achieves a synergistic effect through the combined use of anionic and cationic surfactants, and the combined use of inorganic coagulants and organic flocculants. This synergistic effect significantly enhances the efficiency of individual surfactants and coagulants, and significantly improves sludge dewatering efficiency. This combined conditioning agent exhibits high efficiency over a wide pH range, therefore, no pre-adjustment of the pH value is required during use, avoiding corrosion of equipment by acidic environments. Furthermore, this sludge deep dewatering combined conditioning agent is suitable for sludge from municipal wastewater treatment plants with different sludge characteristics, demonstrating good adaptability. Using this combined conditioning agent in sludge treatment can significantly improve dewatering efficiency, greatly reduce sludge volume, thereby reducing the cost of subsequent treatment and disposal, and has good economic benefits.

[0138] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A combined conditioner for deep dewatering of sludge, characterized in that, It consists of cationic surfactants, anionic surfactants, coagulants, and flocculants.

2. The sludge deep dewatering combined conditioner according to claim 1, characterized in that, It consists of 100~300 mg / gDS cationic surfactant, 10~30 mg / gDS anionic surfactant, 40~80 mg / gDS coagulant and 3~5 mg / gDS flocculant.

3. The sludge deep dewatering combined conditioner according to claim 1, characterized in that, The cationic surfactant is selected from quaternary ammonium salt cationic surfactants; And / or, the anionic surfactant is selected from sodium dodecylbenzenesulfonate and sodium dodecyl sulfate; And / or, the coagulant is selected from inorganic polymeric coagulants; And / or, the flocculant is selected from organic polymeric flocculants.

4. The sludge deep dewatering combined conditioner according to claim 3, characterized in that, The quaternary ammonium salt cationic surfactant is selected from one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyltrimethylammonium chloride; And / or, the inorganic coagulant is selected from polyaluminum chloride and polyferric sulfate; And / or, the organic flocculant is selected from cationic polyacrylamide and polydimethyldiallyl ammonium chloride.

5. The sludge deep dewatering combined conditioner according to any one of claims 1-4, characterized in that, The mass ratio of the cationic surfactant to the anionic surfactant is 10:1 to 15:

1.

6. A method for conditioning and dewatering sludge using a sludge deep dewatering combination conditioner as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Add cationic and anionic surfactants to the sludge to be treated and stir thoroughly to react; S2. Add coagulant to the sludge to be treated, stir quickly to react and mix thoroughly; then add flocculant, stir slowly to react, let stand, and obtain conditioned sludge. S3. The conditioned sludge is subjected to plate and frame filter press to obtain filtrate and sludge cake.

7. The method according to claim 6, characterized in that, In step S1, when the organic matter content (VSS / TSS) in the sludge to be treated is ≤50%, the dosage of cationic surfactant is 100~200 mg / gDS, and the dosage of anionic surfactant is 10~20 mg / gDS; when the organic matter content (VSS / TSS) in the sludge to be treated is ≥50%, the dosage of cationic surfactant is 200~300 mg / gDS, and the dosage of anionic surfactant is 20~30 mg / gDS.

8. The method according to claim 6, characterized in that, In S1, when the sludge zeta potential value is below -15mV, the coagulant dosage is 60~80mg / gDS and the flocculant dosage is 4~5mg / gDS; when the sludge zeta potential value is above -15mV, the coagulant and flocculant dosages can be reduced to 40~60mg / gDS and 3~4mg / gDS, respectively. And / or, in S1, the solid content of the sludge to be treated is 10 g / L to 30 g / L.

9. The method according to claim 6, characterized in that, In step S2, a coagulant solution is added, wherein the mass concentration of the coagulant in the coagulant solution is 5% to 10%. And / or, in S2, the added flocculant is cationic polyacrylamide with a molecular weight greater than 3 million, and when a cationic polyacrylamide solution is added, the mass concentration of cationic polyacrylamide in the cationic polyacrylamide solution is 0.1%~0.4%; Alternatively, in S2, the added flocculant is polydimethyl diallyl ammonium chloride with a molecular weight greater than 10 million, and when the polydimethyl diallyl ammonium chloride solution is added, the mass concentration of polydimethyl diallyl ammonium chloride in the polydimethyl diallyl ammonium chloride solution does not exceed 20%.

10. The method according to claim 6, characterized in that, In S2, the speed of the rapid stirring reaction is 300 r / min, and the time is 10~20 min; And / or, in S2, the stirring speed is 60 r / min and the time is 10~20 min; And / or, in S2, the settling time is 10~30min; And / or, a plate and frame filter press is used to mechanically filter the conditioned sludge. The filter cloth of the plate and frame filter press is made of polypropylene long fiber. The filter plates of the plate and frame filter press are provided with filter chambers on both sides. Flat cylindrical protruding particles are densely distributed on the bottom surface of the filter chamber. The protruding particles are evenly distributed in a spiral shape outward from the central through hole of the filter plate.

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