A sludge deep dewatering conditioner for municipal sewage treatment plants and its application method

Abstract

The present application relates to sewage treatment technical field, specifically, it relates to a kind of urban sewage treatment plant sludge deep dewatering conditioning agent and its application method, it includes the following raw materials: functionalization layered composite powder, cationic polyacrylamide, diatomite and sodium carbonate.Functionalization layered composite powder is used in the present application, after bentonite is organically modified by lauryl trimethylammonium bromide, interlayer spacing significantly increases, with excellent hydrophobicity and cation exchange capacity, can efficiently neutralize the negative charge on the surface of sludge colloid, destroy double electric layer structure, release part of bound water;Iron hydroxide deposited on its surface as amphoteric metal hydroxide, further through electric neutralization compresses double electric layer, and forms amorphous reticular structure, acts as high-efficiency adsorption flocculation net, captures small sludge particles;The synergistic effect of the powder and cationic polyacrylamide realizes the efficient removal of sludge bound water and intracellular water, achieves the dual goal of deep dewatering and sludge cake volume reduction.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a deep dewatering conditioner for sludge in urban wastewater treatment plants and its application method. Background Technology

[0002] The residual sludge produced by urban wastewater treatment plants has a high water content and large volume. Its efficient dewatering and safe disposal are key factors restricting the stable operation and sustainable development of wastewater treatment plants. Conventional sludge conditioning and mechanical dewatering methods (such as using polyacrylamide flocculants in combination with belt filter presses) can usually only reduce the sludge water content to about 80%, and the resulting sludge cake is still in a fluid plastic state. Subsequent transportation, landfilling or resource utilization are costly and pose environmental risks. Against this background, deep dewatering processes based on conditioner modification and high-pressure filter presses have been widely studied and applied. Among them, conditioning technology using mineral powder as a framework building block shows good prospects.

[0003] Among them, Chinese patent CN102381828B discloses a sludge dewatering composite conditioner and its application method. The sludge dewatering composite conditioner prepared therein can effectively destroy the polymers in the sludge and reduce the compressibility of organic matter by synergistic effect between Fenton reagent and / or Fenton-like reagent and the skeletal structure of the powder, thereby significantly improving the sludge dewatering performance.

[0004] However, conventional mineral powders used in existing technologies (such as lime, fly ash, and ordinary bentonite) mainly rely on physical adsorption to remove some of the free water between sludge flocs. However, their surface chemical properties are limited, making it difficult to effectively disrupt the stable structure of colloidal particles, displace tightly bound water, or break down microbial cell walls to release intracellular water, resulting in a low dewatering limit. In view of this, we propose a deep dewatering conditioner for sludge in urban wastewater treatment plants and its application method. Summary of the Invention

[0005] The purpose of this invention is to provide a deep dewatering conditioner for sludge from urban wastewater treatment plants and its application method, in order to solve the problem mentioned in the background art that conventional mineral powders (such as lime, fly ash, ordinary bentonite, etc.) used in the prior art mainly rely on physical adsorption to remove some of the free water between sludge flocs. However, their surface chemical properties are simple, which cannot effectively destroy the stable structure of colloidal particles, make it difficult to displace tightly bound water, and make it impossible to break down the cell walls of microorganisms to release intracellular water, resulting in a low dewatering limit.

[0006] This invention provides a deep dewatering conditioner for sludge from urban wastewater treatment plants, comprising the following raw materials: functionalized layered composite powder, cationic polyacrylamide, diatomaceous earth, and sodium carbonate;

[0007] The functionalized layered composite powder is prepared by organically cationically modifying bentonite with lauryltrimethylammonium bromide and then depositing ferric hydroxide on its surface.

[0008] Preferably, the preparation method of the functionalized layered composite powder is as follows:

[0009] Lauryltrimethylammonium bromide was added to deionized water to obtain a cationic solution;

[0010] The cationic solution was added dropwise to the bentonite suspension while stirring at 300-600 rpm for 30-60 min. After the addition was complete, stirring was continued for 1-2 h to obtain the mixture.

[0011] The mixture was placed in a water bath at 40-60℃ and stirred for 1 hour, then cooled to room temperature; washed 3-5 times with deionized water, filtered and collected the solid; the solid was dried at 60-80℃ for 12 hours to obtain organic modified bentonite;

[0012] Organically modified bentonite was redispersed in deionized water at a solid-liquid ratio of 1:10 and sonicated at 100-200W power for 5-10 minutes to obtain an organically modified bentonite suspension.

[0013] Add 0.5 mol / L ferric chloride hexahydrate solution to the organic modified bentonite suspension and stir at 300-400 rpm for 30 min; adjust the pH to 8-9 with 1.0 mol / L sodium hydroxide and continue stirring for 30-60 min; then age in a water bath at 50-80℃ for 1-3 h; after the reaction is complete, wash with deionized water until neutral, filter and collect the wet solid; dry at 60-80℃ for 12 h to obtain functionalized layered composite powder.

[0014] Preferably, the mass concentration of the cation solution is 3-5%.

[0015] Preferably, the bentonite suspension is obtained by adding bentonite to deionized water at a solid-liquid ratio of 1:10 and stirring at 200-300 rpm for 30 minutes at room temperature.

[0016] Preferably, the dry basis mass ratio of lauryltrimethylammonium bromide to bentonite is 0.3-0.5:1.

[0017] Preferably, the dry weight ratio of iron ions in the ferric chloride hexahydrate solution to organically modified bentonite is 0.05-0.20:1.

[0018] On the other hand, the present invention provides a method for applying a deep dewatering conditioner for sludge in urban wastewater treatment plants, the method being as follows:

[0019] S1.1. The functionalized layered composite powder, cationic polyacrylamide and diatomaceous earth are mixed evenly in proportion to obtain the conditioner powder;

[0020] S1.2 Take sludge from an urban wastewater treatment plant and adjust its moisture content to 95-98%; add conditioning agent powder and stir at 200-300 rpm for 5-10 minutes, during which time the pH is adjusted to 7.5-8.5 with sodium carbonate to obtain the conditioned sludge.

[0021] S1.3. The conditioned sludge is fed into a plate and frame filter press to obtain sludge cake.

[0022] Preferably, in step S1.1, the mass ratio of functionalized layered composite powder, cationic polyacrylamide, and diatomaceous earth is 2-5:0.6:1.

[0023] Preferably, in step S1.2, the mass ratio of the conditioner powder to the sludge is 1:50-200.

[0024] Preferably, in step S1.3, the filtration pressure of the plate and frame filter press is 0.3-0.6 MPa, and the filtration time is 20-40 min.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention discloses a deep dewatering conditioner for sludge in urban wastewater treatment plants and its application method. It utilizes a functionalized layered composite powder. Bentonite, after organic modification with lauryltrimethylammonium bromide, exhibits significantly increased interlayer spacing, excellent hydrophobicity, and cation exchange capacity. This allows for efficient neutralization of the negative charge on the surface of sludge colloids, disrupting the double-layer structure and releasing some bound water. The iron hydroxide deposited on its surface, acting as an amphoteric metal hydroxide, further neutralizes and compresses the double layer, forming an amorphous network structure that serves as a highly efficient adsorption and flocculation network, capturing fine sludge particles. The synergistic effect of this powder and cationic polyacrylamide makes the floc structure denser and more hydrophobic. This significantly reduces the dosage of the conditioner while achieving efficient removal of bound water and intracellular water from the sludge, achieving the dual goals of deep dewatering and sludge cake volume reduction. Detailed Implementation

[0027] 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 the present invention.

[0028] This invention provides a deep dewatering conditioner for sludge from urban wastewater treatment plants, comprising the following raw materials: functionalized layered composite powder, cationic polyacrylamide, diatomaceous earth, and sodium carbonate;

[0029] The functionalized layered composite powder is prepared by organically cationically modifying bentonite with lauryltrimethylammonium bromide and then depositing ferric hydroxide on its surface.

[0030] The following products were purchased from Shanghai Yuanye Biotechnology Co., Ltd.: lauryltrimethylammonium bromide (CAS No. 1119-94-4, purity 99%), bentonite (CAS No. 1302-78-9, purity CP, montmorillonite content ≥85%, cation exchange capacity (CEC) ≥80mmol / 100g), diatomaceous earth (CAS No. 61790-53-2, purity CP), and sodium carbonate (CAS No. 497-19-8, purity AR, 99.8%).

[0031] Ferric chloride hexahydrate (CAS No. 10025-77-1, purity AR, 99%) was purchased from Shandong Xiya Chemical Co., Ltd.

[0032] Cationic polyacrylamide (CAS No. 25085-02-3, purity 99%) was purchased from Hubei Xinkang Pharmaceutical Chemical Co., Ltd.

[0033] The specific steps for adjusting the sludge moisture content to 95%–98% are as follows: if the moisture content of the sludge to be treated is higher than 98%, it is first reduced to below 98% by gravity thickening or mechanical thickening; if the moisture content of the sludge to be treated is lower than 95%, the filtrate or supernatant from the sewage treatment plant is added for dilution and stirred evenly.

[0034] Example 1: A method for applying a deep dewatering conditioner for sludge in urban wastewater treatment plants, comprising the following steps:

[0035] S1.1. The functionalized layered composite powder, cationic polyacrylamide and diatomaceous earth are mixed evenly at a mass ratio of 2:0.6:1 to obtain the conditioner powder;

[0036] S1.2 Take sludge from a municipal wastewater treatment plant and adjust its moisture content to 95%; add conditioning agent powder, wherein the mass ratio of conditioning agent powder to sludge is 1:50, stir at 300 rpm for 10 min, and adjust the pH to 7.5 with sodium carbonate during the process to obtain the conditioned sludge.

[0037] S1.3. The conditioned sludge is fed into a plate and frame filter press. The filtration pressure is 0.6 MPa and the filtration time is 20 min to obtain sludge cake.

[0038] The preparation method of functionalized layered composite powder is as follows:

[0039] Adding lauryltrimethylammonium bromide to deionized water yields a cation solution with a mass concentration of 3%.

[0040] Bentonite was added to deionized water at a solid-liquid ratio of 1:10, and stirred at 300 rpm for 30 min at room temperature to obtain a bentonite suspension.

[0041] The cationic solution was added dropwise to the bentonite suspension, wherein the dry weight ratio of lauryltrimethylammonium bromide to bentonite was 0.3:1. The mixture was stirred at 300 rpm for 60 min, and after the addition was complete, the stirring was continued for 2 h to obtain the mixture.

[0042] The mixture was placed in a 60°C water bath and stirred for 1 hour, then cooled to room temperature; washed three times with deionized water, and the solid was collected by filtration; the solid was dried at 60°C for 12 hours to obtain organic modified bentonite.

[0043] Organically modified bentonite was redispersed in deionized water at a solid-liquid ratio of 1:10 and sonicated at 100W for 5 minutes to obtain an organically modified bentonite suspension.

[0044] A 0.5 mol / L ferric chloride hexahydrate solution was added to an organically modified bentonite suspension, wherein the dry weight ratio of iron ions in the ferric chloride hexahydrate solution to the organically modified bentonite was 0.05:1. The mixture was stirred at 300 rpm for 30 min. The pH was adjusted to 8 with 1.0 mol / L sodium hydroxide, and stirring was continued for another 30 min. The mixture was then aged in a water bath at 50 °C for 3 h. After the reaction was completed, the mixture was washed with deionized water until neutral, and the wet solid was collected by filtration. The solid was dried at 60 °C for 12 h to obtain the functionalized layered composite powder.

[0045] Example 2: The difference between this example and Example 1 is that the mass ratio of the dry basis of bentonite to lauryltrimethylammonium bromide is 1:0.4.

[0046] Example 3: The difference between this example and Example 1 is that the mass ratio of the dry basis of bentonite to lauryltrimethylammonium bromide is 1:0.5.

[0047] Example 4: The difference between this example and Example 1 is that the dry weight ratio of iron ions in the ferric chloride hexahydrate solution to organically modified bentonite is 0.12:1.

[0048] Example 5: The difference between this example and Example 1 is that the dry weight ratio of iron ions in the ferric chloride hexahydrate solution to organically modified bentonite is 0.20:1.

[0049] Zeta potential determination: 0.01 g of functionalized layered composite powder sample was dispersed in 100 mL of deionized water and ultrasonically treated for 5 minutes at 100 W power using an ultrasonic disperser to ensure uniform particle dispersion and prepare the suspension to be tested; the suspension was drawn up with a microsyringe and injected into a dedicated Zeta potential sample cell; the sample cell was placed in a Zeta potential analyzer, the appropriate temperature was set (e.g., 25 °C), and the instrument was run; the instrument calculates the electrophoretic mobility of the particles using laser velocimetry and automatically converts it into a Zeta potential value.

[0050] Contact angle determination: Take a small amount of dried functionalized layered composite powder and press it into a flat and dense sheet under a specific pressure using a powder press; fix the sheet on the sample stage of the contact angle measuring instrument; use the instrument's high-precision syringe to slowly add a drop of ultrapure water (about 2 μL) to the surface of the sheet; use the Young-Laplace equation to fit the water droplet profile and calculate the static contact angle.

[0051] Determination of centrifugal dewatering rate: Prepare a series of simulated sludge samples with known dry weight (e.g., 1.0 g) (or use raw sludge from a wastewater treatment plant), add a quantitative amount of functionalized layered composite powder (e.g., 5% of dry weight); after conditioning according to the application method, take an equal amount of conditioned sludge (e.g., 10 g) and place it in a centrifuge tube with a filter membrane, centrifuge at a constant speed (e.g., 4000 rpm) for 10 minutes; immediately after centrifugation, remove the sludge cake and weigh its wet weight; calculate the centrifugal dewatering rate: Dewatering rate = (mass of sludge before conditioning - wet weight of sludge cake after centrifugation) / mass of sludge before conditioning × 100%.

[0052] Table 1 Performance data of functionalized layered composite powders

[0053] Zeta potential Contact angle Centrifugal dehydration rate Example 1 +25.6mV 78.5° 62.3% Example 2 +35.2mV 105.8° 68.7% Example 3 +33.5mV 98.4° 66.1% Example 4 +38.9mV 92.1° 71.5% Example 5 +40.5mV 85.3° 65.8%

[0054] Comparing Examples 1, 2, and 3, it can be seen that as the proportion of lauryltrimethylammonium bromide increases from 0.3 to 0.4, the Zeta potential of the powder (from +25.6mV to +35.2mV) and the contact angle (from 78.5° to 105.8°) are significantly improved. This indicates that the higher organic loading effectively enhances the charge neutralization capacity and hydrophobicity of the powder, which directly leads to the peak value of centrifugal dehydration rate (68.7%).

[0055] However, when the ratio was further increased to 0.5 (Example 3), the contact angle and dehydration rate decreased instead, indicating that the excessive surfactant began to form a hydrophilic bilayer structure or blocked some pores, which had a slight inhibitory effect on performance.

[0056] Comparing Examples 1, 4, and 5, it can be seen that as the iron ion ratio increases from 0.05 to 0.12, the Zeta potential continues to increase significantly (from +25.6 mV to +38.9 mV), which is due to the strong charge neutralization effect of iron hydroxide. At the same time, the centrifugal dehydration rate reaches a peak of 71.5%, indicating that a moderate iron load forms an effective adsorption flocculation network and framework structure, which greatly improves the dehydration channel.

[0057] However, when the iron ratio was too high, up to 0.20 (Example 5), although the Zeta potential was the highest, the contact angle and dehydration rate both decreased significantly. This confirms that excessive iron hydroxide will agglomerate, block the interlayer and pores of bentonite, impair its hydrophobicity and ability to form water transport channels, and lead to deterioration of dehydration performance.

[0058] Example 6: A method for applying a deep dewatering conditioner for sludge in urban wastewater treatment plants, comprising the following steps:

[0059] S1.1. The functionalized layered composite powder, cationic polyacrylamide and diatomaceous earth are mixed evenly at a mass ratio of 4:0.6:1 to obtain the conditioner powder;

[0060] S1.2 Take sludge from a municipal wastewater treatment plant and adjust its moisture content to 98%; add conditioning agent powder, wherein the mass ratio of conditioning agent powder to sludge is 1:120, stir at 300 rpm for 10 min, and adjust the pH to 8.0 with sodium carbonate during the process to obtain the conditioned sludge.

[0061] S1.3. The conditioned sludge is fed into a plate and frame filter press. The filtration pressure is 0.4 MPa and the filtration time is 40 min to obtain sludge cake.

[0062] The preparation method of functionalized layered composite powder is as follows:

[0063] Adding lauryltrimethylammonium bromide to deionized water yields a cation solution with a mass concentration of 4%.

[0064] Bentonite was added to deionized water at a solid-liquid ratio of 1:10, and stirred at 300 rpm for 30 min at room temperature to obtain a bentonite suspension.

[0065] The cationic solution was added dropwise to the bentonite suspension, with a dry weight ratio of lauryltrimethylammonium bromide to bentonite of 0.4:1. The mixture was stirred at 400 rpm for 60 min, and stirred for 2 h after the addition was complete to obtain a mixed solution.

[0066] The mixture was placed in a 60℃ water bath and stirred for 1 hour, then cooled to room temperature; it was washed 5 times with deionized water, and the solid was collected by filtration; the solid was dried at 60℃ for 12 hours to obtain organic modified bentonite.

[0067] Organically modified bentonite was redispersed in deionized water at a solid-liquid ratio of 1:10 and sonicated at 200W for 10 minutes to obtain an organically modified bentonite suspension.

[0068] A 0.5 mol / L ferric chloride hexahydrate solution was added to an organically modified bentonite suspension, wherein the dry weight ratio of iron ions in the ferric chloride hexahydrate solution to the organically modified bentonite was 0.12:1. The mixture was stirred at 400 rpm for 30 min. The pH was adjusted to 8 with 1.0 mol / L sodium hydroxide, and stirring was continued for 60 min. The mixture was then aged in a water bath at 60 °C for 3 h. After the reaction was completed, the mixture was washed with deionized water until neutral, and the wet solid was collected by filtration. The solid was dried at 60 °C for 12 h to obtain the functionalized layered composite powder.

[0069] Example 7: The difference between this example and Example 6 is that the mass ratio of functionalized layered composite powder, cationic polyacrylamide and diatomaceous earth is 2:0.6:1.

[0070] Example 8: The difference between this example and Example 6 is that the mass ratio of functionalized layered composite powder, cationic polyacrylamide and diatomaceous earth is 5:0.6:1.

[0071] Example 9: The difference between this example and Example 6 is that the mass ratio of the conditioner powder to the sludge is 1:50.

[0072] Example 10: The difference between this example and Example 6 is that the mass ratio of the conditioner powder to the sludge is 1:200.

[0073] Determination of mud cake moisture content: Take a complete mud cake from the plate and frame filter press, and immediately take a certain amount (e.g., about 20g) of mud cake sample and put it into a pre-weighed evaporating dish or weighing bottle (weight recorded as M1). Quickly weigh the total mass of "evaporating dish + wet mud cake" and record it as M2. Place the sample in an oven at 105±5℃ until constant weight is achieved (usually takes 6-8 hours or longer). After removal, place it in a desiccator to cool to room temperature, and quickly weigh the total mass of "evaporating dish + dry mud cake" and record it as M3. Calculate the mud cake moisture content = [(M2-M3) / (M2-M1)]×100%.

[0074] Method for determining the solid content of mud cake: Take the mud cake obtained after pressure filtration and dry it at 105±5℃ to constant weight. The solid content of mud cake is calculated by the following formula: Solid content of mud cake = (mass of mud cake after drying / mass of mud cake before drying) × 100%.

[0075] Determination of capillary water absorption time: Take a small amount of "conditioned sludge" sample (no need for pressure filtration), and use a dedicated capillary water absorption time meter to inject the sample into the sample cell of the instrument; start the instrument and automatically record the time required for water to penetrate a certain distance (usually 1 cm) on the filter paper by capillary penetration, which is the CST value, and the unit is seconds.

[0076] Table 2 Performance data for sludge deep dewatering applications

[0077] Moisture content of mud cake Solid content of mud cake Capillary water absorption time Example 6 54.2% 45.8% 14.3s Example 7 61.8% 38.2% 21.5s Example 8 52.5% 47.5% 12.8s Example 9 49.8% 50.2% 10.5s Example 10 65.3% 34.7% 35.2s

[0078] Comparing Examples 6, 7, and 8, it can be seen that when the proportion of functionalized layered composite powder increased from 2 (Example 7) to 4 (Example 6), the moisture content of the cake decreased significantly from 61.8% to 54.2% (achieving the deep dehydration target). At the same time, the solid content of the cake increased from 38.2% to 45.8%, and the CST also decreased significantly from 21.5 seconds to 14.3 seconds. This proves the core role of the functional powder in breaking down bound water and constructing water transport channels.

[0079] When the ratio was further increased to 5 (Example 8), the moisture content improved slightly (52.5%), but the solid content of the cake also increased to 47.5%; this indicates that adding too much powder will increase the final solid content of the cake and bring about a certain volume increase effect, which needs to be balanced between economic efficiency and volume reduction goals.

[0080] Comparing Examples 6, 9, and 10, it can be seen that when the dosage is increased from 1:200 (Example 10) to 1:120 (Example 6), the moisture content decreases from 65.3% (not up to standard) to 54.2%, and the CST improves from 35.2 seconds (extremely poor dehydration) to 14.3 seconds; this proves that sufficient dosage is a prerequisite for ensuring effective conditioning.

[0081] When the dosage was further increased to 1:50 (Example 9), the dewatering effect was the best (moisture content 49.8%, CST 10.5 seconds, cake solids content 50.2%); this meant that more conditioner was needed to process one ton of sludge and more cake was produced, resulting in the highest processing cost.

[0082] Based on the above measurements, Example 6 is selected as the optimal example.

[0083] Comparative Example 1: The difference between this comparative example and Example 6 is that no functionalized layered composite powder was added.

[0084] Comparative Example 2: The difference between this comparative example and Example 6 is that no functionalized layered composite powder was added, and bentonite was used directly.

[0085] Comparative Example 3: The difference between this comparative example and Example 6 is that iron hydroxide was not deposited in the preparation method of the functionalized layered composite powder.

[0086] Comparative Example 4: The difference between this comparative example and Example 6 is that the preparation method of the functionalized layered composite powder did not involve organic cation modification.

[0087] Table 3 Performance data for sludge deep dewatering applications

[0088] Moisture content of mud cake Solid content of mud cake Capillary water absorption time Example 6 54.2% 45.8% 14.3s Comparative Example 1 ＞75% ＜25.0% ＞60s Comparative Example 2 68.5% 31.5% 35.0s Comparative Example 3 60.1% 39.9% 22.7s Comparative Example 4 64.8% 35.2% 29.4s

[0089] Comparative Example 1 (without any added functional powder) performed the worst, with a cake moisture content >75% and a CST >60 seconds. This indicates that cationic polyacrylamide (CPAM) and diatomaceous earth alone cannot form an effective dewatering channel. The sludge flocs are compressed and compacted during filter press, preventing water from being discharged, and deep dewatering completely fails.

[0090] Comparative Example 2 (using virgin bentonite) performed much better than Comparative Example 1, but was still far inferior to Example 6; this proves that virgin bentonite can only serve as a physical framework and cannot effectively exert the chemical conditioning functions of charge neutralization and hydrophobic cell disruption, resulting in limited dehydration efficiency (CST=35.0 seconds) and dehydration limit (moisture content 68.5%).

[0091] Although the moisture content of the sludge cake in Comparative Example 3 (without deposited iron) (60.1%) was better than that in Comparative Example 2 (original bentonite, 68.5%), it was still significantly higher than that in Example 6 (54.2%). This confirms that while organic modification alone can provide hydrophobicity, the deposition of iron hydroxide plays an irreplaceable dual synergistic role: iron species can effectively neutralize the negative charge on the surface of sludge colloids and form larger flocs through hydroxyl bridging, an effect that cannot be achieved by organic modification alone; the deposition of amorphous iron hydroxide between layers can produce a pillaring effect, effectively opening and fixing the interlayer spacing of the organic bentonite, thereby forming a more stable and interconnected porous water transport channel during the pressure filtration process; Comparative Example 3 lacks this rigid framework, and its channels are more prone to collapse under pressure, resulting in the release of water that cannot be discharged quickly and completely, thus limiting the dewatering limit.

[0092] Comparative Example 4 (without organic modification) lacks the hydrophobic effect of long-chain organic alkyl groups. Although iron modification provides a certain charge neutralization capacity, the powder is highly hydrophilic and cannot effectively "strip" bound water, and it will block the channels. Therefore, its dehydration efficiency (CST=29.4 seconds) and effect (water content 64.8%) are not ideal.

[0093] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A deep dewatering conditioner for sludge from urban wastewater treatment plants, characterized in that, The raw materials include: functionalized layered composite powder, cationic polyacrylamide, diatomaceous earth, and sodium carbonate; The functionalized layered composite powder is prepared by organically cationically modifying bentonite with lauryltrimethylammonium bromide and then depositing iron hydroxide on its surface. The preparation method of the functionalized layered composite powder is as follows: Lauryltrimethylammonium bromide was added to deionized water to obtain a cationic solution; The cationic solution was added dropwise to the bentonite suspension while stirring at 300-600 rpm for 30-60 min. After the addition was complete, stirring was continued for 1-2 h to obtain the mixture. The mixture was placed in a water bath at 40-60℃ and stirred for 1 hour, then cooled to room temperature; washed 3-5 times with deionized water, filtered and collected the solid; the solid was dried at 60-80℃ for 12 hours to obtain organic modified bentonite; Organically modified bentonite was redispersed in deionized water at a solid-liquid ratio of 1:10 and sonicated at 100-200W power for 5-10 minutes to obtain an organically modified bentonite suspension. Add 0.5 mol / L ferric chloride hexahydrate solution to the organic modified bentonite suspension and stir at 300-400 rpm for 30 min; adjust the pH to 8-9 with 1.0 mol / L sodium hydroxide and continue stirring for 30-60 min; then age in a water bath at 50-80℃ for 1-3 h; after the reaction is complete, wash with deionized water until neutral, filter and collect the wet solid; dry at 60-80℃ for 12 h to obtain functionalized layered composite powder.

2. The sludge deep dewatering conditioner for urban wastewater treatment plants according to claim 1, characterized in that, The mass concentration of the cation solution is 3-5%.

3. The sludge deep dewatering conditioner for urban wastewater treatment plants according to claim 1, characterized in that, The bentonite suspension is obtained by adding bentonite to deionized water at a solid-liquid ratio of 1:10 and stirring at 200-300 rpm for 30 minutes at room temperature.

4. The sludge deep dewatering conditioner for urban wastewater treatment plants according to claim 1, characterized in that, The dry basis mass ratio of lauryltrimethylammonium bromide to bentonite is 0.3-0.5:

1.

5. The sludge deep dewatering conditioner for urban wastewater treatment plants according to claim 1, characterized in that, The dry weight ratio of iron ions in the ferric chloride hexahydrate solution to organically modified bentonite is 0.05-0.20:

1.

6. A method for applying a deep dewatering conditioner for sludge in urban wastewater treatment plants as described in any one of claims 1-5, characterized in that, The application method is as follows: S1.

1. Mix the functionalized layered composite powder, cationic polyacrylamide and diatomaceous earth at a mass ratio of 2-5:0.6:1 to obtain the conditioner powder. S1.2 Take sludge from an urban wastewater treatment plant and adjust its moisture content to 95-98%; add conditioning agent powder, with a mass ratio of conditioning agent powder to sludge of 1:50-200, and stir at 200-300 rpm for 5-10 minutes. During this period, adjust the pH to 7.5-8.5 with sodium carbonate to obtain the conditioned sludge. S1.

3. The conditioned sludge is fed into a plate and frame filter press. The filtration pressure is 0.3-0.6 MPa and the filtration time is 20-40 min to obtain sludge cake.

7. The application method of the sludge deep dewatering conditioner for urban wastewater treatment plants according to claim 6, characterized in that, In S1.1, the mass ratio of functionalized layered composite powder, cationic polyacrylamide, and diatomaceous earth is 4:0.6:

1.

8. The application method of the sludge deep dewatering conditioner for urban wastewater treatment plants according to claim 6, characterized in that, In step S1.2, the mass ratio of the conditioner powder to the sludge is 1:120.