A sludge dewatering conditioner and its application

Abstract

This invention discloses a sludge dewatering conditioner and its application, belonging to the technical field of urban domestic sewage sludge resource utilization. The sludge dewatering conditioner of this invention comprises sludge-based biochar, a dispersant, and a bioenzyme; the sludge-based biochar is prepared using urban domestic sewage sludge as raw material. This invention is applied to the preparation of the sludge dewatering conditioner, specifically including the following steps: 1) bioenzymatic degradation and cell wall disruption; 2) sludge particle dispersion; 3) bioflocculation; 4) formation of a "rigid skeleton" permeation channel; 5) pressure filtration dewatering. Through the synergistic use of bioenzymes, dispersants, and sludge-based biochar, this invention achieves highly efficient sludge dewatering. The conditioning process is simple and rapid, reducing the moisture content of the dewatered sludge to below 50%, thus achieving sludge volume reduction, good environmental benefits, and facilitating subsequent sludge resource utilization.

Description

Technical Field

[0001] This invention relates to the field of urban sewage sludge resource utilization technology, and in particular to a sludge dewatering conditioner and its application. Background Technology

[0002] Sludge dewatering is the process of removing water from sludge to reduce its moisture content to a certain level. Sludge dewatering is achieved by applying external energy or chemicals to alter the sludge floc structure, making water easier to separate and thus achieving dewatering. Based on the way water binds to sludge particles, the water in sludge can be divided into bound water and free water. Bound water is further subdivided into interstitial water, surface water, and bound water based on its binding strength. Free water has a weaker adhesion to sludge particles, while bound water is tightly bound. The energy required to remove different forms of water varies. Free water is relatively easy to remove during dewatering, while bound water is a significant factor limiting sludge dewatering efficiency. Removing this portion of water requires substantial energy, and the trend in sludge moisture content changes with the removal of various water types is related to this energy requirement.

[0003] The dewatering performance of sludge is closely related to the composition and properties of its flocs. Changes in extracellular polymeric substances (EPS), surface charge, and particle size distribution play a decisive role in sludge dewatering. The limiting factors for sludge dewatering can be summarized into three main categories: the poor settling properties of colloidal particles, the high affinity of EPS for water, and the strong compressibility of sludge solids. Coagulation or flocculation is beneficial for improving sludge settling performance. Different technologies can be used to release water from EPS, and adding structural framework materials can help reduce the compressibility of sludge. Sludge particles have a double-electron-layer structure, which refers to the adsorption layer and diffusion layer outside the colloidal core. Sludge contains a large number of colloidal molecules, and the colloidal particles formed by the aggregation of these molecules are called colloidal cores. The colloidal core and adsorption layer are usually combined to form colloidal particles, which, together with the diffusion layer, form aggregates. Sludge particles are generally negatively charged. When cationic electrolytes are added, cations flood into the diffusion layer and even the adsorption layer, increasing the cation concentration in the double electron layer. This thins the diffusion layer, reduces the negative charge on the surface of the particle core, and compresses the double electron layer spacing, thus reducing the electrostatic repulsion between particles. This enhances particle aggregation and settling performance. EPS is one of the most important components of activated sludge. Its molecular weight, chemical properties, and structure are particularly important for pollutant removal and sludge characteristics. EPS is mainly a collective term for high molecular weight substances such as proteins and polysaccharides, affecting sludge flocculation, settling, and dewatering properties. Changes in EPS content increase the difficulty of sludge treatment due to the following factors: increased intercellular repulsion, weakening the flocculation performance of sludge particles; hydrophilic substances in EPS retain a large amount of water and increase the content of interstitial water; the formed stable colloidal structure prevents water from seeping out of the floc pores; a thin layer forms between the filter media and the sludge cake, blocking water channels; and increased sludge viscosity. Due to their complex colloidal structure, sludge particles experience a gradual decrease in volume reduction during mechanical dewatering. This leads to the gradual accumulation of a gelatinous cake on the filter media surface, increasing the difficulty of further pressure filtration and dewatering. The specific resistance of the sludge also increases with increasing pressure. The high compressibility of sludge makes it prone to deformation under pressure, resulting in a thickened filter cake that clogs the pores where the cake contacts the filter cloth, ultimately reducing the sludge's dewatering performance. Improving the porosity of the sludge cake and reducing its compressibility has become a new research direction. Research focuses on selecting inexpensive, readily available, and environmentally friendly filter aids with high porosity and a robust structure to act as skeletal structures and reduce sludge compressibility.

[0004] Mechanical dewatering can only remove free water and some interstitial water between sludge particles. Capillary water, with its strong binding force between sludge particles, requires significant mechanical force and energy. The content of internally bound water is related to the proportion of microbial cells in the sludge, and mechanical methods are ineffective in removing this water; high-temperature heating and freezing are often necessary. High-temperature heating typically employs thermal drying, where the heat energy breaks down the bound water within sludge cells, achieving deep dewatering. However, thermal drying technologies often utilize steam or flue gas, resulting in high treatment costs, large exhaust gas volumes, and large cooling water requirements. Furthermore, it poses risks of secondary pollution from odors and dust, as well as the risk of dust explosions. The investment and operating costs of sludge thermal drying are generally high, with equipment investment typically ranging from 200,000 to 500,000 RMB per ton of wet sludge and operating costs exceeding 200 to 300 RMB per ton of wet sludge. This results in high requirements and conditions for sludge thermal drying projects, hindering widespread application.

[0005] To reduce the cost of deep dewatering, chemical conditioning combined with plate and frame filter press technology is now widely used, resulting in lower overall operating costs compared to thermal drying. Commonly used chemical conditioners include inorganic conditioners composed of ferric chloride, quicklime, and fly ash. However, for sludge with an 80% moisture content, achieving good dewatering results requires sophisticated equipment and processes, with the total amount of conditioner exceeding 20% ​​of the sludge volume, leading to significant sludge volume increase and failing to achieve actual sludge reduction. Furthermore, some conditioners combine inorganic conditioners with polyacrylamide, which can reduce the total amount of conditioner added to some extent. However, because polyacrylamide is a viscous slurry, it can affect filtration and subsequent treatment effects and poses pollution problems such as difficulty in degradation.

[0006] Sludge dewatering and conditioning technology still suffers from the following three major shortcomings and drawbacks: 1. The amount of conditioning agent added is relatively large, resulting in a significant increase in sludge volume, which seriously affects the subsequent resource utilization of sludge and is also detrimental to its safe disposal. 2. The sludge conditioning process is relatively complex and not suitable for large-scale deep dewatering applications. 3. The economic and environmental benefits are relatively poor, with high investment and operating costs.

[0007] Therefore, it is very important to provide a sludge dewatering conditioner to improve the sludge dewatering rate. Summary of the Invention

[0008] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a sludge dewatering conditioner, which achieves efficient sludge dewatering, with a simple and quick conditioning process, reducing the moisture content of the dewatered sludge to below 50%.

[0009] In a second aspect, the present invention provides an application of the above-mentioned sludge dewatering conditioner.

[0010] According to a first aspect of the present invention, a sludge dewatering conditioner is provided, the sludge dewatering conditioner comprising sludge-based biochar, a dispersant, and a bioenzyme.

[0011] The sludge dewatering conditioner according to the first aspect of the present invention has at least the following beneficial effects:

[0012] This invention, through the synergistic effect of biological enzymes, dispersants, and sludge-based biochar, exhibits significant synergistic effects compared to single conditioners. It can achieve efficient sludge dewatering, with a simple and quick conditioning process. The moisture content of the dewatered sludge is reduced to below 50%, achieving sludge volume reduction, good environmental benefits, and facilitating subsequent sludge resource utilization.

[0013] According to some embodiments of the present invention, the sludge-based biochar has pores with a pore size of 2 to 100 nm.

[0014] Therefore, the sludge-based biochar has interconnected internal structures, and the micropores develop into mesopores, which effectively increases the specific surface area of ​​the sludge-based biochar. This is beneficial for forming water diffusion channels within the sludge system during its use as a sludge conditioner, which facilitates water discharge, promotes dehydration, and ensures a stable skeletal structure that can effectively maintain smooth drainage through the dehydration channels.

[0015] According to some embodiments of the present invention, the sludge-based biochar is a sludge-based biochar prepared from municipal sewage sludge.

[0016] According to some embodiments of the present invention, the method for preparing the sludge-based biochar includes the following steps:

[0017] After the first pyrolysis treatment of urban sewage sludge, it is washed, dried, crushed, impregnated with alkali, and then subjected to a second pyrolysis treatment to obtain sludge-based biochar.

[0018] The first pyrolysis treatment causes the organic matter in the municipal sewage sludge to condense, cross-link, and carbonize. The resulting solid product can be further pyrolyzed in a second treatment to improve the yield and specific surface area of ​​sludge-based biochar. By performing two pyrolysis treatments, the energy quality of the sludge is improved at the source, solving the problem of high moisture content and low calorific value in the sludge.

[0019] According to some embodiments of the present invention, the urban sewage sludge has a moisture content of 90% to 100%.

[0020] Preferably, the water content of the municipal sewage sludge is approximately 93-99%.

[0021] More preferably, the moisture content of the municipal sewage sludge is approximately 95.3%.

[0022] According to some embodiments of the present invention, the atmosphere for the first pyrolysis is an inert atmosphere of 99.99% nitrogen or argon.

[0023] According to some embodiments of the present invention, the temperature of the first pyrolysis treatment is 200°C to 400°C.

[0024] Preferably, the temperature of the first pyrolysis treatment is 250°C.

[0025] According to some embodiments of the present invention, the duration of the first pyrolysis treatment is 1 to 3 hours.

[0026] Preferably, the first pyrolysis treatment takes 1.5 hours.

[0027] According to some embodiments of the present invention, the washing step is to wash the product obtained from the first pyrolysis with ultrapure water, repeating 2 to 3 times.

[0028] The purpose of washing is to remove excess impurities.

[0029] According to some embodiments of the present invention, the drying temperature is 100°C to 120°C.

[0030] According to some embodiments of the present invention, the drying and combing instrument is an oven.

[0031] According to some embodiments of the present invention, the method for preparing the sludge-based biochar further includes passing it through a 200-mesh sieve after the crushing treatment.

[0032] According to some embodiments of the present invention, the immersion conditions are: soaking in a 5-30 wt% alkaline solution and standing for 0.5-3 days.

[0033] Preferably, the immersion conditions are: soaking in a 10wt% alkaline solution and standing for 1 day.

[0034] According to some embodiments of the present invention, the alkaline solution is at least one of KOH solution and NaOH solution.

[0035] According to some embodiments of the present invention, the solid-liquid ratio of the impregnation is 1g:1-2g.

[0036] According to some embodiments of the present invention, the impregnation method is an equal-volume impregnation method.

[0037] According to some embodiments of the present invention, the steps of the equal-volume impregnation method are as follows: S1: Determine the water absorption rate of the crushed biochar: Take 10g of crushed biochar and weigh it as m1. Soak it in deionized water for 1 hour, then take it out and drain the water. Wipe the surface free water with absorbent paper and weigh it as m2. Then the water absorption rate = (m2-m1) / m1*100%, which is the mass of water that a unit mass of carrier (the carrier is the pyrolyzed, crushed and sieved sludge-based biochar) can absorb. Since the density of water is about 1g / ml, the water absorption rate can also be regarded as the volume of solution that a unit mass of carrier can absorb; S2: Prepare the impregnation solution: Weigh the carrier to be impregnated as m3, calculate the mass of active component required for impregnation, and prepare it into an equal-volume impregnation solution with a volume of m3*water absorption rate. Impregnation: Place the carrier in a container, add the equal-volume impregnation solution, and stir evenly.

[0038] According to some embodiments of the present invention, the atmosphere of the second pyrolysis treatment is an inert atmosphere of nitrogen or argon with a purity of ≥99.99%.

[0039] According to some embodiments of the present invention, the conditions for the second pyrolysis treatment are: pyrolysis constant temperature of 500℃~600℃, and pyrolysis constant temperature residence time of 25~35min.

[0040] Preferably, the conditions for the second pyrolysis treatment are: pyrolysis constant temperature of 550℃~580℃, and pyrolysis constant temperature residence time of 28~33min.

[0041] More preferably, the conditions for the second pyrolysis treatment are: pyrolysis constant temperature of 550°C, and pyrolysis constant temperature residence time of 30 min.

[0042] According to some embodiments of the present invention, the bioenzyme is at least one selected from neutral protease, mesophilic amylase, cellulase, lipase, snail enzyme, and lysozyme.

[0043] Preferably, the bioenzyme is a mixture of neutral protease, mesophilic amylase and cellulase in a mass ratio of 1-3:1-3:1-3.

[0044] Preferably, the bio-enzyme is a mixture of lysozyme and snail enzyme in a mass ratio of 1-3:1-3.

[0045] Preferably, the bioenzyme is a mixture of neutral protease, cellulase, lipase, snail enzyme, and lysozyme in a mass ratio of 1-3:1-3:1-3:1-3:1-3:1-3.

[0046] Preferably, the bioenzyme is a mixture of mesophilic amylase, cellulase, snail enzyme, and lysozyme in a mass ratio of 1-3:1-3:1-3:1-3.

[0047] According to some embodiments of the present invention, the mass concentration of the biological enzyme liquid is 1% to 3%.

[0048] According to some embodiments of the present invention, the dispersant comprises wood sulfonate and polyalkyl aromatic sulfonate.

[0049] According to some embodiments of the present invention, the lignosulfonate is at least one of calcium lignosulfonate, sodium lignosulfonate, and magnesium lignosulfonate.

[0050] According to some embodiments of the present invention, the polyalkyl aromatic sulfonate is at least one of naphthalene sulfonate formaldehyde condensate, alkyl naphthalene sulfonate formaldehyde condensate, and melamine resin sulfonate condensate.

[0051] Lignosulfonates are polycyclic organic polymers containing a large number of negatively charged groups. They have a strong affinity for high-valence metal ions, enabling metal ions in wastewater to settle rapidly, which is beneficial for metal recovery. They also have good diffusion properties, are soluble in water of any hardness, have good chemical stability in aqueous solution, and are biodegradable.

[0052] Polyalkyl aromatic sulfonates are anionic surfactants. Their molecular structure is characterized by hydrophilic groups composed of sulfonate groups and hydrophobic groups composed of organic hydrocarbon groups, resulting in a highly polar molecule.

[0053] According to some embodiments of the present invention, the mass ratio of the wood sulfonate to the polyalkyl aromatic sulfonate is 2 to 5:1.

[0054] According to some embodiments of the present invention, the biofilm is composed of at least one of a cellulose carrier and a polyester carrier, and a fungus of the genus Aspergillus.

[0055] Preferably, the biofilm is composed of a polyester carrier and a fungus of the genus Aspergillus.

[0056] The cell walls of Aspergillus molds contain galactomannan. As the molds grow, galactomannan is released into the environment. This water-soluble organic polymer can improve the floc structure, increase the floc density, and greatly improve the sludge settling performance, which is beneficial for subsequent sludge dewatering.

[0057] According to a second aspect of the present invention, an application of the above-mentioned sludge dewatering conditioner in sludge dewatering is proposed.

[0058] According to some embodiments of the present invention, the sludge dewatering method uses the sludge-based biochar as a raw material for preparing the sludge dewatering conditioner.

[0059] According to some embodiments of the present invention, the sludge dewatering method includes the following steps:

[0060] S1. The sludge to be treated is enzymatically hydrolyzed using the aforementioned biological enzyme;

[0061] S2. Mix the sludge obtained in step S1 with the dispersant;

[0062] S3. Treat the sludge obtained in step S2 with the biofilm;

[0063] S4. The sludge obtained by conditioning step S3 with the sludge-based biochar;

[0064] S5. Dewater the sludge obtained in step S4 by filter pressing.

[0065] S5. After the sludge treated in step S4 is filtered by pressure, a deeply dewatered sludge cake is obtained.

[0066] The application of the second aspect of the present invention has at least the following beneficial effects:

[0067] This invention first releases water from EPS through bio-enzymatic degradation, then improves the settling performance of sludge through coagulation or flocculation by chemical dispersants and biological treatment, and finally adds solid residue from the pyrolysis of activated sludge to reduce the compressibility of sludge. Through the combined effect of the above chemical and biological conditioning and rigid framework, the floc structure in sludge can be effectively destroyed and the permeability of sludge can be improved, releasing adsorbed water, bound water and intracellular water as much as possible, improving the dewatering performance of sludge, and ultimately making the sludge moisture content reach below 50%.

[0068] According to some embodiments of the present invention, in step S1, the amount of the added bio-enzyme by pure weight is 0.5-1% of the dry basis of the sludge;

[0069] Preferably, in step S1, the amount of the added bio-enzyme is 0.7-0.9% of the dry basis of the sludge.

[0070] According to some embodiments of the present invention, in step S1, the enzymatic hydrolysis time is 60 to 180 min.

[0071] Preferably, in step S1, the enzymatic hydrolysis time is 90–120 min.

[0072] Neutral protease, mesophilic amylase, cellulase, lipase, snail enzyme, and lysozyme can degrade polysaccharides and proteins in extracellular polymeric substances (EPS), thereby degrading EPS, destroying the EPS structure, and converting bound water in EPS into free water. The destruction of the EPS structure allows the free water in EPS to flow out, thus improving the sludge dewatering performance.

[0073] Firstly, enzymatic hydrolysis can break down the cell walls of microorganisms, degrade large organic molecules such as EPS, and change the structure of sludge flocs, which is beneficial for the subsequent dispersion of dispersants and can reduce the amount and cost of subsequent dispersants (chemical agents).

[0074] According to some embodiments of the present invention, in step S2, the amount of dispersant added is 0.2 to 0.6% of the dry weight of the sludge.

[0075] Preferably, in step S2, the amount of dispersant added is 0.3 to 0.5% of the dry weight of the sludge.

[0076] According to some embodiments of the present invention, the reaction time of step S2 is 5 to 15 minutes.

[0077] Preferably, the reaction time of step S2 is 10 to 12 minutes.

[0078] When lignin sulfonate is added to sludge, the hydrophobic groups of lignin sulfonate are directionally adsorbed on the surface of sludge particles, while the hydrophilic groups point towards the aqueous solution, forming a monomolecular or multimolecular adsorption film. This causes the sludge particles to be dispersed due to the mutual repulsion of the same surface charge, releasing excess water from between the particles to achieve dehydration.

[0079] When naphthalene sulfonate formaldehyde polymer is added to sludge, the hydrophobic groups of the naphthalene sulfonate formaldehyde polymer molecules are directionally adsorbed on the surface of sludge micro-particles, while the hydrophilic groups form a protective layer outside the micro-particles. The electric double layer grid on the surface of the micro-particles increases rapidly. Due to the mutual repulsion of like charges, the sludge flocculent particles that are already wrapped with water are dispersed, releasing the wrapped water.

[0080] The sludge dewatering method provided by this invention reduces the use of traditional flocculants polyacrylamide and polyaluminum chloride by adjusting the steps and using dispersants, thereby reducing secondary pollution and achieving significant environmental benefits.

[0081] According to some embodiments of the present invention, the processing time of step S3 is 12 to 24 hours.

[0082] Preferably, the processing time for step S3 is 16 to 19 hours.

[0083] Biofilm treatment is inexpensive, recyclable, and can degrade organic pollutants. Due to the population effect, the cells in the biofilm have a strong resistance to toxicity, which is 50 to 500 times stronger than that of free cells. Biofilms also have a strong ability to adapt to changes in water quality.

[0084] According to some embodiments of the present invention, in step S4, the amount of sludge-based biochar added is equivalent to 25% to 100% of the dry weight of the sludge.

[0085] Preferably, in step S4, the amount of sludge-based biochar added is equivalent to 60-80% of the dry weight of the sludge.

[0086] According to some embodiments of the present invention, the reaction time of step S4 is 5 to 15 minutes.

[0087] Preferably, the reaction time of step S4 is 8 to 12 minutes.

[0088] According to some embodiments of the present invention, in step S5, the conditions for the pressure filtration process are: feed pressure of 1.6 MPa and pressing pressure of 1.8 MPa.

[0089] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0090] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0091] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0092] Plate and frame filter press: B M A 900-U; Shandong Jingjin Filter Press Group Co., Ltd.

[0093] Specific surface area analyzer: 3H-2000-A; Best Instruments Technology (Beijing) Co., Ltd.

[0094] Source of urban sewage sludge: Baishigang Water Purification Center.

[0095] Test method for moisture content of sludge cake: CJ / T221-2005 Test method for sludge from urban wastewater treatment plants.

[0096] Specific surface area of ​​municipal sewage sludge before treatment: 6.08 m² 2 / g.

[0097] The properties and parameters of the sludge used in the specific implementation are shown in Table 1.

[0098] Table 1. Detection results of original samples of municipal sewage sludge

[0099]

[0100] Table 2. Main element content (wt%) of sludge-based biochar after the second pyrolysis in Example 1.

[0101]

[0102] Example 1

[0103] This embodiment prepares a sludge-based biochar, and the specific steps are as follows:

[0104] The municipal sewage sludge undergoes a first pyrolysis treatment at a temperature of 250℃ for 1.5 hours. Before heating, nitrogen or argon gas with a purity of ≥99.99% is introduced to create an inert atmosphere.

[0105] Then, the sludge-based biochar obtained by pyrolysis was repeatedly washed with ultrapure water to remove impurities and dried in an oven at 105°C. The dried sludge-based biochar was crushed, passed through a 200-mesh sieve, and the sieve material was obtained. The sludge-based biochar powder was activated by impregnation with 10wt% KOH solution using an equal volume impregnation method and allowed to stand at room temperature for 1 day.

[0106] Then, a second pyrolysis treatment is carried out, with the pyrolysis temperature constant at 550℃ and the pyrolysis constant temperature holding time for 30 minutes. Before heating, 99.99% nitrogen or argon gas is introduced to form an inert atmosphere, and sludge-based biochar is obtained.

[0107] This embodiment also provides a method for sludge dewatering using the wastewater conditioner obtained in this embodiment. The steps of the above sludge dewatering method are as follows:

[0108] S1. First reaction adjustment: Add 2wt% biological enzyme to the sludge to be treated, and add 10mM Tris-HCl (pH 8.0) dispersion. The biological enzyme is a mixture of neutral protease, mesophilic amylase and cellulase in a mass ratio of 1:1:1. The amount of biological enzyme added is equivalent to 0.8% of the dry weight of the sludge, and the reaction time is 120min.

[0109] S2. Second reaction adjustment: Add a dispersant to the sludge treated in step S1. The dispersant is a sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate; the mass ratio of sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate is 3:1; the amount of dispersant added is 0.4% of the dry weight of the sludge, and the reaction time is 10 min.

[0110] S3. Third reaction adjustment: The sludge treated in step S2 is subjected to biofilm treatment. The biofilm consists of a polyester carrier and Aspergillus species. The treatment time is 18 hours.

[0111] S4. Fourth reaction adjustment: Add sludge-based biochar to the sludge treated in step S3. The amount of sludge biochar added is 75% of the dry weight of the sludge, and the treatment time is 10 minutes.

[0112] S5. The sludge treated in step S4 is subjected to deep dewatering using a plate and frame filter press with a feed pressure of 1.6 MPa and a pressing pressure of 1.8 MPa to obtain a deep-dewatered sludge cake.

[0113] Example 2

[0114] This embodiment prepares a sludge-based biochar, and the specific steps are as follows:

[0115] The municipal sewage sludge undergoes a first pyrolysis treatment at a temperature of 250℃ for 1.5 hours. Before heating, nitrogen or argon gas with a purity of ≥99.99% is introduced to create an inert atmosphere.

[0116] Then, the sludge-based biochar obtained by pyrolysis was repeatedly washed with ultrapure water to remove impurities and dried in an oven at 105°C. The dried sludge-based biochar was crushed, passed through a 200-mesh sieve, and the sieve material was obtained. The sludge-based biochar powder was activated by impregnation with 10wt% KOH solution using an equal volume impregnation method and allowed to stand at room temperature for 1 day.

[0117] Then, a second pyrolysis treatment is carried out, with the pyrolysis temperature constant at 550℃ and the pyrolysis constant temperature holding time for 30 minutes. Before heating, 99.99% nitrogen or argon gas is introduced to form an inert atmosphere, and sludge-based biochar is obtained.

[0118] This embodiment also provides a method for sludge dewatering using the wastewater conditioner described in this embodiment. The steps of the above-mentioned sludge dewatering method are as follows:

[0119] S1. First reaction adjustment: Add 2wt% biological enzyme to the sludge to be treated, and add 10mM Tris-HCl (pH 8.0) dispersion. The biological enzyme is a mixture of lysozyme and snail enzyme in a mass ratio of 1:1. The amount of biological enzyme added is equivalent to 0.7% of the dry weight of the sludge, and the reaction time is 100min.

[0120] S2. Second reaction adjustment: Add a dispersant to the sludge treated in step S1. The dispersant is a sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate; the mass ratio of sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate is 4:1; the amount of dispersant added is 0.5% of the dry weight of the sludge, and the reaction time is 10 min.

[0121] S3. Third reaction adjustment: The sludge treated in step S2 is subjected to biofilm treatment. The biofilm is composed of cellulose carrier and / or polyester carrier and Aspergillus species. The treatment time is 16 hours.

[0122] S4. Fourth reaction adjustment: Add sludge-based biochar to the sludge treated in step S3. The amount of sludge biochar added is 80% of the dry weight of the sludge, and the treatment time is 8 minutes.

[0123] S5. The sludge treated in step S4 is subjected to deep dewatering using a plate and frame filter press with a feed pressure of 1.6 MPa and a pressing pressure of 1.8 MPa to obtain a deep-dewatered sludge cake.

[0124] Example 3

[0125] This embodiment prepares a sludge-based biochar, and the specific steps are as follows:

[0126] The municipal sewage sludge undergoes a first pyrolysis treatment at a temperature of 250℃ for 1.5 hours. Before heating, nitrogen or argon gas with a purity of ≥99.99% is introduced to create an inert atmosphere.

[0127] Then, the sludge-based biochar obtained by pyrolysis was repeatedly washed with ultrapure water to remove impurities and dried in an oven at 105°C. The dried sludge-based biochar was crushed, passed through a 200-mesh sieve, and the sieve material was obtained. The sludge-based biochar powder was activated by impregnation with 10wt% KOH solution using an equal volume impregnation method and allowed to stand at room temperature for 1 day.

[0128] Then, a second pyrolysis treatment is carried out, with the pyrolysis temperature constant at 550℃ and the pyrolysis constant temperature holding time for 30 minutes. Before heating, 99.99% nitrogen or argon gas is introduced to form an inert atmosphere, and sludge-based biochar is obtained.

[0129] This embodiment also provides a method for sludge dewatering using the wastewater conditioner described in this embodiment. The steps of the above-mentioned sludge dewatering method are as follows:

[0130] S1. First reaction adjustment: Add 2wt% biological enzyme to the sludge to be treated, and add 10mM Tris-HCl (pH 8.0) dispersion. The biological enzyme is a neutral protease, and the mass ratio of cellulase, lipase, snail enzyme and lysozyme is 1:1:1:1:1. The amount of biological enzyme added is equivalent to 0.9% of the dry weight of the sludge, and the reaction time is 90min.

[0131] S2. Second reaction adjustment: Add a dispersant to the sludge treated in step S1. The dispersant is a sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate; the mass ratio of sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate is 2:1; the amount of dispersant added is 0.4% of the dry weight of the sludge, and the reaction time is 12 min.

[0132] S3. Third reaction adjustment: The sludge treated in step S2 is subjected to biofilm treatment. The biofilm is composed of cellulose carrier and / or polyester carrier and Aspergillus species. The treatment time is 19 hours.

[0133] S4. Fourth reaction adjustment: Add sludge-based biochar to the sludge treated in step S3. The amount of sludge biochar added is 60% of the dry weight of the sludge, and the treatment time is 12 minutes.

[0134] S5. The sludge treated in step S4 is subjected to deep dewatering using a plate and frame filter press with a feed pressure of 1.6 MPa and a pressing pressure of 1.8 MPa to obtain a deep-dewatered sludge cake.

[0135] Example 4

[0136] This embodiment prepares a sludge-based biochar, and the specific steps are as follows:

[0137] The municipal sewage sludge undergoes a first pyrolysis treatment at a temperature of 250℃ for 1.5 hours. Before heating, nitrogen or argon gas with a purity of ≥99.99% is introduced to create an inert atmosphere.

[0138] Then, the sludge-based biochar obtained by pyrolysis was repeatedly washed with ultrapure water to remove impurities and dried in an oven at 105°C. The dried sludge-based biochar was crushed, passed through a 200-mesh sieve, and the sieve material was obtained. The sludge-based biochar powder was activated by impregnation with 10wt% KOH solution using an equal volume impregnation method and allowed to stand at room temperature for 1 day.

[0139] Then, a second pyrolysis treatment is carried out, with the pyrolysis temperature constant at 550℃ and the pyrolysis constant temperature holding time for 30 minutes. Before heating, 99.99% nitrogen or argon gas is introduced to form an inert atmosphere, and sludge-based biochar is obtained.

[0140] This embodiment also provides a method for sludge dewatering using the wastewater conditioner described in this embodiment. The steps of the above-mentioned sludge dewatering method are as follows:

[0141] S1. First reaction adjustment: Add 2wt% biological enzyme to the sludge to be treated, and add 10mM Tris-HCl (pH 8.0) dispersion. The biological enzyme is a mixture of mesophilic amylase, cellulase, snail enzyme and lysozyme in a mass ratio of 1:1:1:1. The amount of biological enzyme added is equivalent to 0.5% of the dry weight of the sludge, and the reaction time is 105min.

[0142] S2. Second reaction adjustment: Add a dispersant to the sludge treated in step S1. The dispersant is a sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate; the mass ratio of sodium lignosulfonate and naphthalene sulfonate formaldehyde condensate is 5:1; the amount of dispersant added is 0.3% of the dry weight of the sludge, and the reaction time is 12 min.

[0143] S3. Third reaction adjustment: The sludge treated in step S2 is subjected to biofilm treatment. The biofilm is composed of cellulose carrier and / or polyester carrier and Aspergillus species. The treatment time is 19 hours.

[0144] S4. Fourth reaction adjustment: Add sludge-based biochar to the sludge treated in step S3. The amount of sludge biochar added is 60% of the dry weight of the sludge, and the treatment time is 12 minutes.

[0145] S5. The sludge treated in step S4 is subjected to deep dewatering using a plate and frame filter press with a feed pressure of 1.6 MPa and a pressing pressure of 1.8 MPa to obtain a deep-dewatered sludge cake.

[0146] Comparative Example 1

[0147] The application of a sludge-based biochar in the preparation of a composite sludge dewatering conditioner is specifically different from that in Example 1 in that step S1 is not included, i.e., no biological enzymes are added for degradation and cell wall breaking.

[0148] Comparative Example 2

[0149] The application of a sludge-based biochar in the preparation of a composite sludge dewatering conditioner is specifically different from that in Example 1 in that step S1 is not included, i.e., no dispersant is added.

[0150] Comparative Example 3

[0151] The application of a sludge-based biochar in the preparation of a composite sludge dewatering conditioner is specifically different from that in Example 1 in that step S1 is not included, i.e., no biofilm treatment is performed.

[0152] Comparative Example 4

[0153] The application of a sludge-based biochar in the preparation of a composite sludge dewatering conditioner is specifically different from that in Example 1 in that step S4 is not included, i.e., no sludge-based biochar is added.

[0154] Comparative Example 5

[0155] The application of a sludge-based biochar in the preparation of a composite sludge dewatering conditioner is specifically different from that in Example 1 in that the pyrolysis raw material is red mud.

[0156] Table 3 shows the content (wt%) of major elements in the red mud of Comparative Example 5.

[0157]

[0158] Test case

[0159] This test example tested the moisture content and specific surface area of ​​the sludge cakes obtained in the examples and comparative examples. The specific test method was: "CJ / T221-2005 Test Method for Sludge from Urban Wastewater Treatment Plants". The test results are shown in Table 4.

[0160] Table 4. Moisture content of treated sludge cake and specific surface area of ​​pyrolytic biochar as a sludge dewatering conditioner in corresponding test cases.

[0161] project Moisture content of mud cake (%) <![CDATA[Specific surface area (m 2 / g)]]> Example 1 47.5％ 160 Example 2 48.3％ 152 Example 3 48.6％ 143 Example 4 48.1％ 136 Comparative Example 1 58.8％ 160 Comparative Example 2 56.7％ 160 Comparative Example 3 54.7％ 160 Comparative Example 4 61.2％ / Comparative Example 5 53.6％ 98

[0162] The experimental results in Table 3 show that the final sludge cake moisture content in Examples 1-4 of this invention all reached below 50%. Compared with Comparative Example 5, the specific surface area of ​​the pyrolytic biochar, which plays the role of the "carbon skeleton" in sludge dewatering and conditioning, was effectively improved in other test examples. Combined with the results of Comparative Examples 1-4, it can be seen that this invention, through the synergistic effect of biological enzymes, dispersants, and sludge-based biochar, has a significant synergistic effect, achieving efficient sludge dewatering, reducing sludge volume, and facilitating subsequent sludge resource utilization. Based on the experimental results of Comparative Example 5, this invention, using municipal sewage sludge as the raw material, achieves a higher dewatering rate than sludge-based biochar prepared using red mud as the raw material. Therefore, this invention can be widely applied to wastewater and sludge treatment in industries such as chemical and municipal engineering, and is particularly suitable for the treatment of municipal sewage sludge from urban wastewater treatment plants.

[0163] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. The application of a sludge dewatering conditioner in sludge dewatering, characterized in that, The sludge dewatering conditioner includes sludge-based biochar, dispersant, and biological enzymes; The sludge-based biochar is prepared by a method comprising the following steps: After the first pyrolysis treatment of municipal sewage sludge, it is washed, dried, crushed, and then impregnated with alkali, followed by a second pyrolysis treatment to obtain sludge-based biochar. The temperature of the first pyrolysis treatment is 200℃~400℃, and the time is 1~3h. The impregnation conditions are: soaking in a 5~30wt% alkaline solution and standing for 0.5~3d. The conditions of the second pyrolysis treatment are: the constant temperature of the pyrolysis is 500℃~600℃, and the constant temperature residence time of the pyrolysis is 25~35min. The sludge-based biochar has pores with a pore size of 2~100 nm; The dispersant is lignin sulfonate and polyalkyl aromatic sulfonate; the mass ratio of lignin sulfonate to polyalkyl aromatic sulfonate is 2-5:

1. The sludge dewatering method includes the following steps: S1. The sludge to be treated is enzymatically hydrolyzed using the aforementioned biological enzyme; S2. Mix the sludge obtained in step S1 with the dispersant; S3. Treat the sludge obtained in step S2 with a biofilm; S4. The sludge obtained by conditioning step S3 with the sludge-based biochar; S5. Dewater the sludge obtained in step S4 by filter press; The biofilm is composed of at least one of a cellulose carrier and a polyester carrier, and a fungus of the genus Aspergillus.

2. The application according to claim 1, characterized in that, The bioenzyme is at least one of neutral protease, mesophilic amylase, cellulase, lipase, snail enzyme, and lysozyme.

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