Modified sludge dewatering conditioner, preparation method and application thereof, and sludge dewatering method

Abstract

The application discloses a modified sludge dewatering conditioner, a preparation method and application thereof, and a sludge dewatering method. The preparation method comprises the following steps: modifying reaction of a skeleton building agent and a chemical conditioner in a medium solvent, and the chemical conditioner is selected from at least one of an acid inorganic salt conditioner and an acid inorganic polymer flocculant. The above method can improve the surface area, average particle size and Zeta potential of the skeleton building agent through a mixed modification reaction based on existing consumables, improve the filtering aid effect, improve the dewatering performance, and then the maximum utility of the existing consumables can be achieved, so that the sludge dewatering level is improved in a low-cost, simple and green manner, and the high-value resource utilization of the skeleton building agent is realized.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, and in particular to a modified sludge dewatering conditioner, its preparation method and application, and a sludge dewatering method. Background Technology

[0002] In recent years, the rapid growth in wastewater treatment capacity and efficiency has led to a significant increase in excess sludge. Sludge dewatering is a crucial step in sludge reduction, making the development of a highly efficient, green, and cost-effective sludge dewatering agent a top priority in the sludge treatment industry. Fly ash, slag, and other sludge matrix building agents typically contain abundant metal ions and silica-alumina substances, and are commonly used as filter aids in sludge dewatering. Current sludge conditioning methods generally involve adding chemical conditioners to the sludge first, followed by the direct addition of sludge matrix building agents for filtration. However, in this method, the unmodified sludge matrix building agents, such as fly ash, often carry a negative charge on their surface. This negative charge competes with the negative charge of the sludge floc particles for the positive charge of the sludge conditioner, thus hindering the sludge dewatering process. Therefore, there is an urgent need to develop a highly efficient, green, and cost-effective sludge dewatering conditioner and dewatering method. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a modified sludge dewatering conditioner, its preparation method and application, and a sludge dewatering method.

[0004] In a first aspect, the present invention provides a method for preparing a modified sludge dewatering conditioner, comprising the following steps: performing a modification reaction between a skeleton building agent and a chemical conditioner in a medium solvent; wherein the chemical conditioner is selected from at least one of an acidic inorganic salt conditioner and an acidic inorganic polymeric flocculant.

[0005] The preparation method of the modified sludge dewatering conditioner according to embodiments of the present invention has at least the following beneficial effects: The preparation method uses a chemical conditioner and a framework building agent as raw materials, and carries out a modification reaction in a medium solvent. The chemical conditioner dissolves in the solvent, making the reaction system acidic. In the acidic reaction system, at least some impurities on the surface of the framework building agent dissolve, and even the surface of the framework building agent is micro-corroded, and small particles of the framework building agent are corroded away, thereby allowing H2 to be adsorbed on the surface. + This increases the specific surface area and average particle size of the framework building agent, thereby increasing the usable area for water adsorption and also increasing the number of surface adsorption sites. Furthermore, due to the acidic reaction system and the adsorption properties of the framework building agent, it can adsorb H₂. +This increases the zeta potential, thereby improving the filtration effect and enhancing dewatering performance. Therefore, this preparation method, based on existing consumables, enhances their effectiveness through a mixing and modification reaction, improving sludge dewatering levels in a low-cost, simple, and environmentally friendly manner, while also achieving high-value resource utilization of the skeleton building agent.

[0006] In some embodiments of the present invention, the chemical conditioner contains a metal element, specifically a non-heavy metal element that aids in dehydration, typically a divalent or higher metal element, such as any one or more of Al, Fe, Ca, Mg, Zn, and Ti, preferably Al and / or Fe, and more preferably Al. Since sludge floc particles carry a negative charge, the chemical conditioner containing the metal element, when applied to water, can improve the dewatering properties of the sludge through the action of metal ions, for example, some high-valence metal ions (such as Al). 3 + Fe 3+ Ti 4+ High positive charge can neutralize the charge of sludge flocs, weakening their repulsive forces and causing them to aggregate into larger flocs; some divalent metal ions (such as Mg) 2+ Ca 2+ (etc.) can bridge sludge flocs into larger flocs, thus aiding in sludge dewatering. Furthermore, the inventors have discovered that Al... 3+ Fe 3+ Its effect on improving sludge dewatering is significantly better than that of Mg. 2+ Ca 2+ Zn 2+ And Al 3+ Its effect on sludge dewatering (or enhancement effect) is better than Fe. 3+ Ti 4+ Although it has strong charge neutralization properties, it will hydrolyze rapidly in water. Therefore, chemical conditioners are generally preferred to contain Al or Fe elements, and even more preferred to use chemical conditioners containing Al elements.

[0007] In some embodiments of the present invention, the framework building agent contains the metal element, that is, the framework building agent contains at least the same metal element as the metal element in the chemical conditioner; the temperature of the modification reaction is controlled above the dissolution temperature of the metal element in the framework building agent and below the decomposition temperature of the chemical conditioner; the time of the modification reaction is controlled when the metal element in the framework building agent is in a dissolved state or the concentration of the metal ion corresponding to the metal element in the liquid phase returns to the initial reaction state. Wherein, the dissolution temperature of the metal element in the framework building agent refers to the temperature at which the metal element in the framework building agent, at least the same as the metal element contained in the chemical conditioner, can dissolve in the reaction system; the metal element in the framework building agent is in a dissolved state, that is, the content of the metal element in the solid phase is lower than that of the original framework building agent, while the content of the metal ion corresponding to the metal element in the liquid phase is higher.

[0008] Specifically, the chemical conditioner dissolves in the solvent, making the reaction system acidic. This acidic reaction system allows at least some of the metal elements in the framework building agent to dissolve. Furthermore, the inventors discovered during their experimental research that, under conditions above the dissolution temperature of the metal element in the framework building agent (which is the same as that contained in the chemical conditioner) and below the decomposition temperature of the chemical conditioner, the adsorption and dissolution of this metal element (i.e., the same as that contained in the chemical conditioner) in the framework building agent exhibit a cyclical behavior over time during the modification reaction. Specifically, due to the adsorption properties of the framework building agent itself, it first exhibits adsorption properties at the beginning of the reaction. Metal ions in the liquid phase are adsorbed into the framework building agent, and the concentration of metal ions in the liquid phase decreases initially. After reaching the adsorption limit, it enters the dissolution stage, where the metal elements in the framework building agent gradually dissolve, and the concentration of metal ions in the liquid phase slowly increases again. Since the metal elements originally contained in the framework building agent also dissolve, when the dissolution limit is reached, the concentration of metal ions in the liquid phase is higher than the initial state of the reaction. That is, the concentration of metal ions in the liquid phase has increased compared to the initial state of the reaction. Then, it enters the next round of metal ion adsorption stage, where metal ions in the liquid phase are gradually adsorbed into the framework building agent, and the concentration of metal ions in the liquid phase gradually returns to the initial stage of the reaction. Further reaction occurs, and metal ions are further gradually adsorbed into the framework building agent, and the concentration of metal ions in the liquid phase is lower than the initial state of the reaction. After reaching the adsorption limit, the adsorbed metal ions are further dissolved and released, and so on in a cycle. Besides the metal elements contained in the same chemical conditioner (such as Al in AlCl3), the dissolution of other metal elements in the framework building agent did not change significantly over time, but all remained in a dissolved state. However, the inventors' experimental research revealed that the dissolution of metal elements in the framework building agent that are the same as those in the chemical conditioner has a significant impact on the sludge dewatering effect. If metal element A, which is the same as that in the chemical conditioner, is in an adsorbed state while other metal elements are in a dissolved state, and the amount of dissolution is greater than the amount of adsorbed metal element A, the dewatering effect is still not as good as the dewatering effect when metal element A is in a dissolved state or when the concentration of metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase returns to the initial reaction state. As mentioned above, if the reaction time is controlled when the concentration of metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase is lower than the initial reaction state, the dehydration performance of the chemical conditioner may actually be lower than that of the original chemical conditioner. Therefore, in order to avoid the metal ions corresponding to the metal elements contained in the chemical conditioner in the original liquid phase system being reverse-adsorbed into the framework building agent and thus degrading the dehydration performance of the liquid phase, the modification reaction time is generally controlled when the metal elements in the framework building agent that are the same as the metal elements contained in the chemical conditioner are in a dissolved state or when the concentration of metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase returns to the initial reaction state.

[0009] Specifically, if the modification reaction time is controlled until the concentration of metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase system is basically restored to the initial reaction state, the solid-phase framework building agent, after modification treatment and the dissolution of other metal ions, improves the filtration effect and enhances sludge dewatering performance. Preferably, the modification reaction time is controlled until the metal elements in the framework building agent that are the same as the metal elements contained in the chemical conditioner are in a dissolved state. This allows for the effective modification of the liquid phase while simultaneously modifying the solid-phase framework building agent, increasing the content of metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase, which is more conducive to sludge dewatering. Based on the above reaction process, bidirectional modification of both the solid and liquid phases can be achieved; this modification reaction is called a bidirectional modification reaction. Specifically, the bidirectional modification reaction time is generally controlled to be more than 3 hours, and the bidirectional modification reaction time can be determined according to the dissolution of the metal element in the framework building agent that is the same as the metal element contained in the chemical conditioner. Specifically, the reaction time is controlled when the metal element in the framework building agent (the same as the metal element contained in the chemical conditioner) is in a dissolved state; preferably, the bidirectional modification reaction time is controlled at the dissolution limit state of the metal element in the framework building agent, that is, if further reaction is carried out after this, the framework building agent enters the adsorption stage of the corresponding metal ions.

[0010] The skeleton building agent generally contains silicon substances. In some embodiments of the present invention, the skeleton building agent is selected from at least one of fly ash, bottom ash, rice husk ash, silica fume, mineral powder, and red mud.

[0011] The chemical conditioner, acting as a coagulant, primarily conditions the sludge through chemical reactions such as charge neutralization and EPS degradation. In some embodiments of the present invention, the acidic inorganic conditioner is selected from at least one of acidic aluminum salt conditioners, acidic iron salt conditioners, and acidic titanium salt conditioners; the acidic inorganic polymeric flocculant is selected from at least one of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, polyferric chloride, polyferric chloride sulfate, and polyphosphoric ferric chloride. Specifically, the acidic aluminum salt conditioner can be at least one of aluminum chloride, aluminum sulfate, and alum; the acidic iron salt conditioner can be at least one of ferric chloride, ferric sulfate, and ferrous sulfate; and the acidic titanium salt conditioner can be at least one of titanium tetrachloride, titanium sulfate, and aluminum titanate.

[0012] The temperature of the modification reaction can be determined according to the type of chemical conditioner, and is generally controlled above the dissolution temperature of the metal elements in the framework building agent, but below the decomposition temperature of the chemical conditioner. For example, if at least one of acidic aluminum salt conditioner, polyaluminum chloride, and polyaluminum sulfate is selected as the chemical conditioner, the temperature of the modification reaction can be controlled at 25-50°C, and further controlled at 25-35°C, 35-45°C, and 40-50°C. According to the inventor's research and testing, when using the above chemical conditioners and controlling the modification reaction temperature within the above range, the metal elements in the framework building agent can exhibit a better dissolution state. It is preferable to keep the modification reaction temperature at room temperature (around 25°C). At this temperature, there is no need to cool down or heat up, thus saving energy. If the chemical conditioning agent is at least one of acidic ferric salt conditioning agent, polyferric sulfate, polyferric chloride, polyferric chloride sulfate, or polyphosphoric ferric chloride, the inventors' research and experiments have shown that using the above chemical conditioning agents results in poor dissolution of metal elements in the framework building agent at high temperatures. The temperature of the modification reaction can be controlled at 25–30°C, preferably around room temperature (25°C). If the chemical conditioning agent is an acidic titanium salt conditioning agent, the temperature of the modification reaction can be controlled below 10°C, preferably below 5°C, for example, 0–10°C, and further preferably between 0–5°C, preferably around 0°C. Within this temperature range, the hydrolysis rate of the acidic titanium salt conditioning agent can be slowed down, and the metal elements in the framework building agent can be leached out. In addition, as mentioned above, the modification reaction time is generally controlled when the metal elements in the framework building agent (which are the same as the metal elements contained in the chemical conditioner) are in a dissolved state or when the concentration of the metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase returns to the initial reaction state. For example, if an acidic aluminum salt conditioner (such as AlCl3) is used as a chemical conditioner, the modification reaction time can be controlled at around 3 hours or 24 hours, such as 3-4 hours or 24-25 hours; if an acidic titanium salt conditioner (such as TiCl4) is used as a chemical conditioner, the modification reaction time can be controlled at around 24 hours, such as 24-25 hours.

[0013] In some embodiments of the present invention, the modification reaction of the skeleton builder and the chemical conditioner in a medium solvent specifically includes: first dissolving the chemical conditioner in the medium solvent to obtain a chemical conditioner solution, and then adding the skeleton builder to carry out the modification reaction.

[0014] In some embodiments of the present invention, the modification reaction is carried out under stirring. Preferably, the stirring speed during the modification reaction is 500–1500 r / min.

[0015] In some embodiments of the present invention, the chemical conditioning agent contains a metal element, the concentration of the metal ion corresponding to the metal element in the chemical conditioning solution is 400-600 mmol / L, and the liquid-to-solid ratio of the chemical conditioning solution to the skeleton building agent is 3-10 mL / g.

[0016] In some embodiments of the present invention, before the framework building agent and chemical conditioning agent undergo a modification reaction in a medium solvent, the framework building agent is pretreated. The pretreatment includes at least one of cleaning, drying, grinding, and sieving. Preferably, the pretreatment involves sequentially performing cleaning, drying, grinding, and sieving. Specifically, cleaning can be done with deionized water to remove impurities from the surface of the framework building agent; drying can be done by baking at a temperature controlled between 60 and 105°C; and sieving after grinding can be done using a 50-200 mesh sieve.

[0017] In some embodiments of the present invention, after the modification reaction is completed, solid-liquid separation is performed to obtain the modified liquid and / or modified solid phase, thus obtaining a modified sludge dewatering conditioner. The modified liquid can be used alone as the modified sludge dewatering conditioner; or the modified liquid and modified solid phase can be used together as the modified sludge dewatering conditioner; or the modified solid phase can be used as the modified sludge dewatering conditioner in combination with other chemical conditioners (such as unmodified chemical conditioners). When the modified liquid and modified solid phase are used together as the modified sludge dewatering conditioner, or when the modified solid phase is used in combination with other chemical conditioners, the modified solid phase is typically used as a coagulant aid. In general, the modified liquid / other chemical conditioner is added first for coagulation, and then the modified solid phase is added; alternatively, the modified liquid / other chemical conditioner or the modified solid phase can be added simultaneously.

[0018] In some embodiments of the present invention, after solid-liquid separation to obtain the modified liquid and the modified solid phase, the modified solid phase is further subjected to post-treatment and then used in conjunction with the modified liquid as a modified sludge dewatering conditioner. The post-treatment includes at least one of washing and drying. Preferably, the post-treatment is washing and drying in sequence.

[0019] In a second aspect, the present invention provides a modified sludge dewatering conditioner, which is prepared by any of the modified sludge dewatering conditioners proposed in the first aspect of the present invention. The modified sludge dewatering conditioner may be a mixture obtained by modifying a framework builder and a chemical conditioner in a medium solvent; or the modified sludge dewatering conditioner may be a modified liquid and / or a modified solid phase obtained by further solid-liquid separation after modifying a framework builder and a modified conditioner in a medium solvent.

[0020] In a third aspect, the present invention provides the application of one or more modified sludge dewatering conditioners in sludge dewatering.

[0021] A fourth aspect of the present invention provides a sludge dewatering method comprising the following steps:

[0022] S1. Add a modified sludge dewatering conditioner to the sludge for conditioning to obtain conditioned sludge; the modified sludge conditioner includes any of the modified sludge dewatering conditioners proposed in the second aspect of the present invention, or the modified sludge dewatering conditioner prepared by the preparation method of any of the modified sludge dewatering conditioners proposed in the first aspect of the present invention.

[0023] S2. Dewater the conditioning sludge.

[0024] In some embodiments of the present invention, in step S1, the moisture content of the sludge is controlled at 95% to 98%.

[0025] In some embodiments of the present invention, before adding the modified sludge dewatering conditioner to the sludge for conditioning in step S1, the sludge may be concentrated first.

[0026] In some embodiments of the present invention, in step S1, the modified sludge dewatering conditioner is the modified sludge dewatering conditioner prepared by the above method without solid-liquid separation after the modification reaction, and the amount of the modified sludge dewatering conditioner added is 2% to 10% of the dry basis mass of the sludge.

[0027] In some embodiments of the present invention, in step S1, the modified sludge dewatering conditioner includes the modified sludge dewatering conditioner prepared by the above-mentioned method of preparing modified sludge dewatering conditioner by solid-liquid separation after modification reaction. The amount of modified liquid added is 2% to 10% of the dry weight of the sludge; the amount of modified solid added is 5% to 20% of the dry weight of the sludge. The modified liquid can be used alone as a modified sludge conditioner; preferably, the modified liquid and the modified solid phase are used together as a modified sludge dewatering conditioner. In this case, the modified liquid can be added to the sludge first, stirred for 1 to 5 minutes, and then the modified solid phase can be added and stirred for 10 to 20 minutes to obtain conditioned sludge. In some embodiments, the modified solid phase can also be used as a modified sludge dewatering conditioner. In this case, it can be used in combination with other chemical conditioners (such as unmodified chemical conditioners). Specifically, the chemical conditioner can be added to the sludge first, stirred for 1 to 5 minutes, and then the modified solid phase can be added and stirred for 10 to 20 minutes to obtain conditioned sludge.

[0028] In some embodiments of the present invention, in step S2, dewatering specifically involves using a plate and frame filter press or a plate and frame diaphragm filter press to dewater the conditioning sludge; or, dewatering specifically involves using vacuum filtration to dewater the conditioning sludge. Preferably, a plate and frame filter press or a plate and frame diaphragm filter press is used.

[0029] In some embodiments of the present invention, the dewatering pressure of the plate and frame filter press is 1-2 MPa, and the dewatering time can be controlled within 20-30 min; the vacuum filtration pressure is 0.05-0.1 MPa, and the time can be controlled within 5-10 min. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0031] Figure 1 The images show SEM images of the skeleton-building agent fly ash before the modification reaction and the modified solid phase obtained after the modification reaction in Example 1.

[0032] Figure 2 The particle size distribution diagrams are shown for the skeleton-building agent fly ash before the modification reaction and the modified solid phase obtained after the modification reaction in Example 1.

[0033] Figure 3 The images show the XRD patterns of the skeleton-building agent fly ash before the modification reaction and the modified solid phase obtained after the modification reaction in Example 1.

[0034] Figure 4 A comparison chart showing the moisture content and zeta potential of the dewatered sludge cakes obtained from Application Examples 1-3 and Comparative Examples 1-3;

[0035] Figure 5 The graph shows a comparison of the capillary water absorption time, sludge specific resistance, bound water content, and dewatering rate test results of the conditioned sludge obtained from Examples 4 and 5 and Comparative Examples 4 and 5. Detailed Implementation

[0036] 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.

[0037] Example 1

[0038] This embodiment prepares a modified sludge dewatering conditioner, the preparation method of which includes:

[0039] The fly ash used as a skeleton-building agent was pretreated by washing it and then placing it in a forced-air drying oven at 105℃ for 24 hours to remove residual moisture. It was then ground and passed through a 200-mesh sieve. The chemical conditioning agent AlCl3 was dissolved in water to obtain Al... 3 +A chemical conditioning solution of AlCl3 with a concentration of 500 mmol / L was prepared. The AlCl3 solution and the pretreated skeleton building agent fly ash were mixed at a liquid-to-solid ratio of 8 mL / g and stirred at 1000 r / min for 3 h at room temperature (25℃) to carry out the modification reaction, resulting in a mixed solution. The mixed solution was then subjected to solid-liquid separation to obtain a modified liquid and a modified solid phase. The modified solid phase was then washed and dried to obtain the modified sludge dewatering conditioning agent.

[0040] The fly ash used as the skeleton builder was purchased from the fine ash recovered from the flue gas after coal combustion at a coal-fired power plant. Its compound content is shown in Table 1.

[0041] Table 1. Compound content (wt.%) of fly ash as a skeleton-building agent

[0042]

[0043] The concentrations of metal ions in the AlCl3 solution before the modification reaction and in the final modified solution were measured by inductively coupled plasma (ICP). The relative concentration of metal ions dissolved in the modified solution (Formula 1) and the dissolution rate (Formula 2) were calculated to investigate the dissolution of metal elements in the modified skeleton building agent. The results are shown in Table 2.

[0044] Formula 1: C = c – A

[0045]

[0046] In Equation 1, C is the relative concentration of metal ions dissolved in the modified solution (mg / L), c is the measured concentration of metal ions in the modified solution (mg / L), and A is the measured concentration of metal ions in the original chemical conditioning solution (mg / L); in Equation 2, R is the metal ion dissolution rate of the modified solution (%), c is the measured concentration of metal ions in the modified solution (mg / L), V is the volume of the modified solution (L), a is the measured concentration of metal elements in fly ash (mg / kg), and M is the mass of fly ash (kg).

[0047] Table 2. Metal element leaching properties of the modified solution

[0048]

[0049] As shown in Table 2 above, after the modification reaction, the metal ion concentration in the modified solution increased compared to the original chemical conditioning solution (AlCl3 solution). Specifically, Al... 3+ It increased by 7.2%, Ca 2+ It increased by 96.5%, Fe 3+ It increased by 10.8%, Mg 2+The amount increased by 70.3%, indicating that the metal elements in the skeleton building agent that are conducive to dehydration were effectively dissolved after the modification reaction.

[0050] In addition, the SEM images, particle size distribution diagrams, and XRD patterns of the pre-treated skeleton-building agent fly ash and the modified solid phase obtained after the modification reaction are shown below. Figures 1-3 As shown, Figure 1 (a) is the SEM image of the original skeleton building agent fly ash, and (b) is the SEM image of the modified solid phase.

[0051] Depend on Figure 1 As shown in the SEM image, after the modification reaction, many small particles in the original framework-building agent from the fly ash were dissolved by the acidic chemical conditioning solution AlCl3, thus providing more active adsorption sites. Furthermore, tests showed that the specific surface area of ​​the framework-building agent increased from 1.361 m² before the modification reaction. 2 / g increased to 2.176m 2 / g.

[0052] Figure 2 The particle size distribution diagram shows that, compared with the original skeleton building agent fly ash with an average particle size Dx(50) of 436 μm, the average particle size Dx(50) of the modified solid phase obtained after the modification reaction increases to 957 μm, which greatly increases its adsorption area.

[0053] Figure 3 The XRD pattern shown indicates that, compared to the original skeleton building agent fly ash, the modified solid phase obtained after the modification reaction has more quartz peaks with SiO2 as the main substance, indicating that the Si content of the modified solid phase has increased.

[0054] As can be seen from the above, the above modification reaction can achieve bidirectional modification of the solid-phase skeleton building agent fly ash and the liquid-phase chemical conditioning liquid, which is a bidirectional modification reaction.

[0055] Application Example 1

[0056] This application example uses the modified sludge dewatering conditioner prepared in Example 1 above for sludge dewatering. The specific sludge dewatering method is as follows:

[0057] Municipal sludge was collected and subjected to multiple tests. The basic characteristics of this batch of municipal sludge are as follows: MLVSS = 16.09 ± 0.18 g·L⁻¹ -1 TSS = 33.11 ± 0.83 g·L -1 Standard capillary absorption time = 1.67 ± 0.56 s·L·(g·TSS) -1 Bound water content = 94.7 ± 0.7%; sludge specific resistance = 1.30 ± 0.21 10 9 ·s 2 / g; Dehydration rate = 0.60 ± 0.02 mL·s -1 pH = 5.86 ± 0.08; Zeta potential = -12.6 ± 0.4 mV.

[0058] The municipal sludge was concentrated to a moisture content of 96.52% to obtain concentrated sludge. The modified liquid of the modified sludge dewatering conditioner prepared in Example 1 was added to the concentrated sludge, with the amount of modified liquid accounting for 5% of the dry weight of the sludge in the concentrated sludge. The mixture was stirred at 200 r / min for 1 min. Then, the modified solid phase of the modified sludge dewatering conditioner prepared in Example 1 was added, with the amount of modified solid phase accounting for 10% of the dry weight of the sludge in the concentrated sludge. The mixture was stirred at 200 r / min for 2 min, and then stirred at 50 r / min for 15 min to mix evenly to obtain conditioned sludge. The conditioned sludge was then dewatered by plate and frame filter press filtration using a 6-10 μm filter cloth at a pressure of 2 MPa for 30 min to obtain dewatered sludge cake.

[0059] Comparative Example 1

[0060] The difference between this comparative example and application example 1 is that this comparative example directly uses the AlCl3 solution and the pretreated skeleton building agent fly ash from example 1 to replace the modified liquid and modified solid phase in application example 1, and then uses them together for sludge dewatering.

[0061] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 1, concentrate it to a moisture content of 96.52%, and obtain concentrated sludge; add AlCl3 solution from Example 1 to the concentrated sludge, the amount of AlCl3 solution added is 5% of the dry weight of the concentrated sludge, and stir at 200 r / min for 1 min; then add the pretreated skeleton building agent fly ash from Example 1, the amount of fly ash added is 10% of the dry weight of the concentrated sludge, stir at 200 r / min for 2 min, and then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then dewater the conditioned sludge by plate and frame filter press, using a 6-10 μm filter cloth at a pressure of 2 MPa for 30 min, and obtain dewatered sludge cake.

[0062] Example 2

[0063] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Example 1 is that in this embodiment, after the modification reaction, there is no solid-liquid separation, but the mixture obtained after the modification reaction in Example 1 is directly used as the modified sludge dewatering conditioner.

[0064] The specific preparation method is as follows: The fly ash used as a framework building agent is pretreated by washing it and then placing it in a forced-air drying oven at 105℃ for 24 hours to remove residual moisture, followed by sieving through a 200-mesh sieve; the chemical conditioning agent AlCl3 is dissolved in water to obtain Al... 3+ A chemical conditioning solution of AlCl3 with a concentration of 500 mmol / L was prepared. The AlCl3 solution and the pretreated skeleton building agent fly ash were mixed at a liquid-to-solid ratio of 8 mL / g and stirred at 1000 r / min for 3 h at room temperature (25℃) to carry out the modification reaction, and the resulting mixture was the modified sludge dewatering conditioning agent.

[0065] Application Example 2

[0066] This application example applies the modified sludge dewatering conditioner prepared in Example 2 to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 1 in that the modified sludge dewatering conditioner prepared in Example 2 (i.e., the mixed liquid obtained after modification reaction) is used instead of the modified sludge dewatering conditioner prepared in Example 1 (i.e., the modified liquid and modified solid phase obtained after sequential modification reaction and solid-liquid separation) used in Application Example 1. Other operations are basically the same as in Application Example 1.

[0067] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 1, concentrate it to a moisture content of 96.52%, and obtain concentrated sludge; add the modified sludge dewatering conditioner prepared in Example 2 to the concentrated sludge, the amount of modified sludge dewatering conditioner being added is 5% of the dry weight of the sludge in the concentrated sludge, stir at 200 r / min for 3 min; then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then dewater the conditioned sludge by plate and frame filter press, using a 6-10 μm filter cloth at a pressure of 2 MPa for 30 min, and obtain dewatered sludge cake.

[0068] Comparative Example 2

[0069] The difference between this comparative example and application example 2 is that this comparative example uses the AlCl3 solution from example 1 and the pretreated skeleton building agent fly ash directly mixed for sludge dewatering.

[0070] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 1, concentrate it to a moisture content of 96.52%, and obtain concentrated sludge; directly mix the AlCl3 solution from Example 1 and the pretreated skeleton-building agent fly ash to form a mixed liquid, add it to the concentrated sludge, the amount of the mixed liquid added is 5% of the dry weight of the sludge in the concentrated sludge, stir at 200 r / min for 3 min; then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then dewater the conditioned sludge by plate and frame filter press, using a 6-10 μm filter cloth at a pressure of 2 MPa for 30 min, to obtain dewatered sludge cake.

[0071] Example 3

[0072] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Embodiment 1 is that, after modification reaction and solid-liquid separation, the modified liquid is taken separately as the modified sludge dewatering conditioner.

[0073] The specific preparation method is as follows: the skeleton building agent fly ash is pretreated by washing it and placing it in a forced-air drying oven at 105℃ for 24 hours to remove residual moisture from the fly ash, and then passing it through a 200-mesh sieve; the chemical conditioner AlCl3 is dissolved in water to obtain a chemical conditioner solution AlCl3 with a concentration of 500 mmol / L; the AlCl3 solution and the pretreated skeleton building agent fly ash are mixed at a liquid-solid ratio of 8 mL / g, and stirred at 1000 r / min for 3 hours at room temperature (25℃) to carry out the modification reaction and obtain a mixed liquid; then the mixed liquid is separated into solid and liquid, and the modified liquid is taken to obtain the modified sludge dewatering conditioner.

[0074] Application Example 3

[0075] This application example applies the modified sludge dewatering conditioner prepared in Example 3 to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 1 in that the modified sludge dewatering conditioner prepared in Example 3 (i.e., the modified liquid obtained after sequential modification reaction and solid-liquid separation) is used instead of the modified sludge dewatering conditioner prepared in Example 1 (i.e., the modified liquid and modified solid phase obtained after sequential modification reaction and solid-liquid separation). Other operations are basically the same as in Application Example 1.

[0076] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 1, concentrate it to a moisture content of 96.52%, and obtain concentrated sludge; add the modified sludge dewatering conditioner prepared in Example 3 to the concentrated sludge, the amount of the modified sludge dewatering conditioner being added is 5% of the dry weight of the sludge in the concentrated sludge, stir at 200 r / min for 3 min; then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then dewater the conditioned sludge by plate and frame filter press, using a 6-10 μm filter cloth at a pressure of 2 MPa for 30 min, and obtain dewatered sludge cake.

[0077] Comparative Example 3

[0078] The difference between this comparative example and application example 3 is that this comparative example directly uses the AlCl3 solution from example 1 as a sludge dewatering conditioner for sludge dewatering treatment.

[0079] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 1, concentrate it to a moisture content of 96.52%, and obtain concentrated sludge; add AlCl3 solution from Example 1 to the concentrated sludge, the amount of AlCl3 solution added being 5% of the dry weight of the sludge in the concentrated sludge, and stir at 200 r / min for 3 min; then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then dewater the conditioned sludge by plate and frame filter press, using a 6-10 μm filter cloth at a pressure of 2 MPa for 30 min, to obtain dewatered sludge cake.

[0080] Example 4

[0081] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Example 1 is that TiCl4 is used instead of AlCl3 used in Example 1 as the chemical conditioner, and the modification reaction temperature is adjusted from room temperature (25°C) in Example 1 to be carried out in an ice-water bath at 0°C. The reaction time is adjusted from 3h in Example 1 to 24h. Other operations are the same as in Example 1.

[0082] The preparation method is as follows: The fly ash used as a framework building agent is pretreated by washing it and then placing it in a forced-air drying oven at 105℃ for 24 hours to remove residual moisture, followed by sieving through a 200-mesh sieve; the chemical conditioning agent TiCl4 is dissolved in water to obtain Ti... 4+A 500 mmol / L TiCl4 chemical conditioning solution was prepared. The TiCl4 solution and pretreated fly ash as a skeleton building agent were mixed at a liquid-to-solid ratio of 8 mL / g and stirred at 1000 r / min for 24 h in an ice-water bath at 0℃ to carry out the modification reaction, resulting in a mixed solution. The mixed solution was then subjected to solid-liquid separation to obtain a modified liquid and a modified solid phase. The modified solid phase was then subjected to post-treatment such as washing and drying to obtain the modified sludge dewatering conditioner.

[0083] Application Example 4

[0084] This application example applies the modified sludge dewatering conditioner prepared in Example 4 above to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 1 in that: in this application example, the modified sludge dewatering conditioner prepared in Example 4 is used instead of the modified sludge dewatering conditioner prepared in Example 1 used in Application Example 1, and the amount of modified solid phase added is adjusted to 5% of the dry basis mass of the concentrated sludge. The sludge batches are different, and the dewatering method is adjusted. Other specific operations are basically the same as in Application Example 1.

[0085] The specific sludge dewatering method is as follows: Take municipal sludge from the same location but different batches as in Application Example 1, and concentrate it to a water content of 96.74% to obtain concentrated sludge; add the modified liquid from the modified sludge dewatering conditioner prepared in Example 4 to the concentrated sludge, the amount of modified liquid added being 5% of the dry weight of the sludge in the concentrated sludge, and stir at 200 r / min for 1 min; then add the modified solid phase from the modified sludge dewatering conditioner prepared in Example 4, the amount of modified solid phase added being 5% of the dry weight of the sludge in the concentrated sludge, stir at 200 r / min for 2 min, and then stir at 50 r / min for 15 min to mix evenly to obtain conditioned sludge; then test the capillary water absorption time, a dewatering performance index, on the conditioned sludge, and then filter it under vacuum at a fixed pressure of 0.07 MPa for 5 min, and measure and calculate the sludge specific resistance, bound water content, and dewatering rate. The results are as follows. Figure 5 As shown.

[0086] Comparative Example 4

[0087] The difference between this comparative example and application example 4 is that in this comparative example, the TiCl4 solution and the pretreated skeleton building agent fly ash from example 4 were both pretreated in a 0°C refrigerator for 30 minutes, and then taken out and used in conjunction with sludge dewatering.

[0088] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 4, concentrate it to a moisture content of 96.74%, and obtain concentrated sludge; add TiCl4 solution pretreated at 0℃ to the concentrated sludge, the amount of TiCl4 solution added being 5% of the dry weight of the concentrated sludge, and stir at 200 r / min for 1 min; then add fly ash pretreated at 0℃, the amount of fly ash added being 5% of the dry weight of the concentrated sludge, and stir at 200 r / min for 2 min, then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then test the capillary water absorption time, a key dewatering performance indicator, on the conditioned sludge, and then filter it under vacuum at a fixed pressure of 0.07 MPa for 5 min, measuring and calculating the sludge specific resistance, bound water content, and dewatering rate. The results are as follows. Figure 5 As shown.

[0089] Example 5

[0090] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Example 4 is that the temperature conditions of the modification reaction in this embodiment are changed from 0°C ice-water bath in Example 4 to room temperature (25°C). The rest is the same as in Example 1.

[0091] Application Example 5

[0092] This application example applies the modified sludge dewatering conditioner prepared in Example 5 to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 4 in that the modified sludge dewatering conditioner prepared in Example 5 is used instead of the modified sludge dewatering conditioner prepared in Example 4 in Application Example 4. Other operations are the same as in Application Example 4.

[0093] Comparative Example 5

[0094] The difference between this comparative example and application example 5 is that this comparative example uses the TiCl4 solution from example 4 and the pretreated skeleton-building agent fly ash in combination for sludge dewatering.

[0095] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 4, concentrate it to a moisture content of 96.74%, and obtain concentrated sludge; add TiCl4 solution from Example 4 to the concentrated sludge, the amount of TiCl4 solution added being 5% of the dry weight of the concentrated sludge, and stir at 200 r / min for 1 min; then add the pretreated skeleton building agent fly ash from Example 4, the amount of fly ash added being 5% of the dry weight of the concentrated sludge, stir at 200 r / min for 2 min, and then stir at 50 r / min for 15 min, mixing evenly to obtain conditioned sludge; then test the capillary water absorption time, a dewatering performance index, on the conditioned sludge, and then filter it under vacuum at a fixed pressure of 0.07 MPa for 5 min, measuring and calculating the sludge specific resistance, bound water content, and dewatering rate of the dewatered sludge, and the results are as follows. Figure 5 As shown.

[0096] Example 6

[0097] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Example 1 is that the temperature conditions of the modification reaction in this embodiment are adjusted from room temperature (25°C) in Example 1 to 50°C. Other operations are the same as in Example 1.

[0098] Comparative Example 6

[0099] This comparative example prepared a modified sludge dewatering conditioner. The difference between this comparative example and Example 1 is that the temperature conditions of the modification reaction in this comparative example were adjusted from room temperature (25°C) in Example 1 to 80°C, while other operations were the same as in Example 1.

[0100] Example 7

[0101] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Example 1 is that the modification reaction time in this embodiment is adjusted from 3 hours in Example 1 to 24 hours. Other operations are the same as in Example 1.

[0102] Comparative Example 7-1

[0103] This comparative example prepared a modified sludge dewatering conditioner. The difference between this comparative example and Example 1 is that the modification reaction time in this comparative example was adjusted from 3 hours in Example 1 to 12 hours, while other operations were the same as in Example 1.

[0104] Comparative Example 7-2

[0105] This comparative example prepared a modified sludge dewatering conditioner. The difference between this comparative example and Example 1 is that the modification reaction time in this comparative example was adjusted from 3 hours in Example 1 to 1 hour, while other operations were the same as in Example 1.

[0106] Comparative Example 7-3

[0107] This comparative example prepared a modified sludge dewatering conditioner. The difference between this comparative example and Example 1 is that the modification reaction time in this comparative example was adjusted from 3 hours in Example 1 to 2 hours, while other operations were the same as in Example 1.

[0108] Example 8

[0109] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Embodiment 1 is that after modification reaction and solid-liquid separation, the modified solid phase is taken separately as the modified sludge dewatering conditioner. Due to the coagulation aid effect of the modified solid phase, untreated AlCl3 solution is used for coagulation treatment.

[0110] The specific preparation method is as follows: The fly ash used as a framework building agent is pretreated by washing it and then placing it in a forced-air drying oven at 105℃ for 24 hours to remove residual moisture, followed by sieving through a 200-mesh sieve; the chemical conditioning agent AlCl3 is dissolved in water to obtain Al... 3+ A chemical conditioning solution of AlCl3 with a concentration of 500 mmol / L was prepared. The AlCl3 solution and the pretreated skeleton building agent fly ash were mixed at a liquid-to-solid ratio of 8 mL / g and stirred at 1000 r / min for 3 h at room temperature (25℃) to carry out the modification reaction, thereby obtaining a mixed solution. The mixed solution was then subjected to solid-liquid separation, and the modified solid phase was taken to obtain the modified sludge dewatering conditioning agent.

[0111] Application Example 8

[0112] This application example applies the modified sludge dewatering conditioner prepared in Example 8 to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 1 in that the modified sludge dewatering conditioner prepared in Example 8 (i.e., the modified solid phase obtained after sequential modification reaction and solid-liquid separation) is used instead of the modified sludge dewatering conditioner prepared in Example 1 (i.e., the modified liquid and modified solid phase obtained after sequential modification reaction and solid-liquid separation). Untreated AlCl3 solution (i.e., the AlCl3 solution in Example 8) is added for coagulation treatment. The sludge batches are different, and the dewatering method is adjusted. Other operations are basically the same as in Application Example 1.

[0113] The specific sludge dewatering method is as follows: Take municipal sludge from the same location but different batches as in Application Examples 1 and 4, concentrate it to a moisture content of 96.80%, and obtain concentrated sludge; add untreated AlCl3 solution to the concentrated sludge for coagulation, the amount added is 5% of the dry weight of the concentrated sludge, stir at 200 r / min for 1 min, then add the modified sludge dewatering conditioner (i.e., modified solid phase) prepared in Example 8 to the concentrated sludge, the amount added is 10% of the dry weight of the concentrated sludge, then stir at 200 r / min for 2 min, then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then test the capillary water absorption time, a dewatering performance index, on the conditioned sludge, and then filter it under vacuum at a fixed pressure of 0.07 MPa for 5 min, measure and calculate the sludge specific resistance, bound water content and dewatering rate, and the results are shown in Table 6.

[0114] Comparative Example 8

[0115] The difference between this comparative example and application example 8 is that this comparative example directly uses untreated fly ash (i.e., the pretreated skeleton building agent fly ash in example 8) and untreated AlCl3 solution (AlCl3 solution in example 8) in combination for sludge dewatering treatment.

[0116] The specific sludge dewatering method is as follows: Take municipal sludge from the same batch as in Application Example 8, concentrate it to a moisture content of 96.80%, and obtain concentrated sludge; add untreated AlCl3 solution to the concentrated sludge for coagulation, the amount added is 5% of the dry weight of the concentrated sludge, stir at 200 r / min for 1 min, then add untreated fly ash to the concentrated sludge, the amount added is 10% of the dry weight of the concentrated sludge, then stir at 200 r / min for 2 min, then stir at 50 r / min for 15 min, mix evenly, and obtain conditioned sludge; then test the capillary water absorption time, a dewatering performance index, on the conditioned sludge, and then filter it under vacuum at a fixed pressure of 0.07 MPa for 5 min, measure and calculate the sludge specific resistance, bound water content and dewatering rate of the dewatered sludge, and the results are shown in Table 6.

[0117] Example 9

[0118] This embodiment prepares a modified sludge dewatering conditioner. The difference between this embodiment and Example 1 is that in this embodiment, after the chemical conditioner and the skeleton building agent are mixed and dissolved in the medium solution, the modification reaction time is maintained and the mixture is allowed to stand. Other operations are the same as in Example 1.

[0119] The specific preparation method is as follows: the skeleton building agent fly ash is pretreated by washing it and placing it in a forced-air drying oven at 105℃ for 24 hours to remove residual moisture from the fly ash, and then passing it through a 200-mesh sieve; the chemical conditioner AlCl3 is dissolved in water to obtain a chemical conditioner solution AlCl3 with a concentration of 500 mmol / L; the AlCl3 solution and the pretreated skeleton building agent fly ash are mixed at a liquid-solid ratio of 8 mL / g, and allowed to stand at room temperature (25℃) for 3 hours to carry out the modification reaction, resulting in a mixed liquid; then the mixed liquid is subjected to solid-liquid separation to obtain a modified liquid and a modified solid phase, and the modified solid phase is post-treated by washing, drying and other processes to obtain the modified sludge dewatering conditioner.

[0120] Application Example 9

[0121] This application example applies the modified sludge dewatering conditioner prepared in Example 9 to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 8 in that the modified sludge dewatering conditioner prepared in Example 9 (i.e., the modified liquid and modified solid phase obtained after sequential static reaction and solid-liquid separation) is used instead of the modified sludge dewatering conditioner prepared in Example 8 (i.e., the modified liquid and modified solid phase obtained after sequential modification reaction and solid-liquid separation). The sludge batches are different, and the dewatering method is adjusted. Other operations are basically the same as in Application Example 8.

[0122] The specific sludge dewatering method is as follows: Take municipal sludge from the same location but different batches as in Application Examples 1, 4, and 8, and concentrate it to a water content of 96.69% to obtain concentrated sludge; add the modified liquid from the modified sludge dewatering conditioner prepared in Example 9 to the concentrated sludge, the amount of modified liquid added being 5% of the dry weight of the sludge in the concentrated sludge, and stir at 200 r / min for 1 min; then add the modified solid phase from the modified sludge dewatering conditioner prepared in Example 9, the amount of modified solid phase added being 10% of the dry weight of the sludge in the concentrated sludge, stir at 200 r / min for 2 min, and then stir at 50 r / min for 15 min to mix evenly to obtain conditioned sludge; then test the capillary water absorption time, a dewatering performance index, on the conditioned sludge, and then filter it under vacuum at a fixed pressure of 0.07 MPa for 5 min, and measure and calculate the sludge specific resistance, bound water content, and dewatering rate. The results are shown in Table 7.

[0123] Application Example 10

[0124] This application example applies the modified sludge dewatering conditioner prepared in Example 1 to sludge dewatering. The specific sludge dewatering method differs from that in Application Example 9 in that the modified sludge dewatering conditioner prepared in Example 1 (i.e., the modified liquid and modified solid phase obtained after sequential modification reaction and solid-liquid separation) is used instead of the modified sludge dewatering conditioner prepared in Example 9. Other operations are basically the same as in Application Example 9.

[0125] Comparative Example 9

[0126] In this comparative example, the unmodified AlCl3 solution and the unmodified skeleton-building agent fly ash from Comparative Example 1 were used as sludge dewatering conditioners for sludge dewatering. The specific sludge dewatering method differed from that of Application Example 9 in that the sludge dewatering conditioner from Comparative Example 1 was used instead of the modified sludge dewatering conditioner prepared in Example 9. Other operations were basically the same as in Application Example 9.

[0127] The dewatered sludge cakes obtained from sludge dewatering in Examples 1-3 and Comparative Examples 1-3 were subjected to moisture content tests, and the sludge flocs were subjected to Zeta potential tests. The results are as follows: Figure 4 As shown in the figure, the closer the Zeta potential of the sludge flocs is to 0, the more negative charges are neutralized, the better the aggregation, and therefore the easier it is to dewater. This is consistent with the moisture content of the dewatered sludge cake. Furthermore, from... Figure 4 It can be seen that, compared with Comparative Example 1, where AlCl3 solution and fly ash were used separately for sludge dewatering; Comparative Example 2, where AlCl3 solution and fly ash were directly mixed for sludge dewatering; and Comparative Example 3, where AlCl3 solution was used alone, Application Example 1, where the modified liquid and modified solid phase were used separately for sludge dewatering; Application Example 2, where the mixed liquid obtained after the modification reaction was used directly for sludge dewatering; and Application Example 3, where the modified liquid was used alone for sludge dewatering, all showed lower moisture content in the dewatered sludge cake and a closer Zeta potential to 0 in the sludge flocs. Specifically, the moisture content of the dewatered sludge filter cake in Application Example 3 was reduced by 17.3% compared to Comparative Example 3; the moisture content of the dewatered sludge filter cake in Application Example 1 was reduced by 19.1% compared to Comparative Example 1; and the moisture content of the dewatered sludge filter cake in Application Example 2 was reduced by 18.4% compared to Comparative Example 2. Therefore, it can be concluded that the modified sludge dewatering conditioner obtained through the modification reaction can effectively improve sludge dewatering performance. In addition, in Comparative Example 2, AlCl3 solution and fly ash were directly mixed for sludge dewatering. However, when the mixture was directly used for sludge dewatering, the reaction time was very short, and metal ions could not be dissolved. Fly ash itself carries a negative charge, which will compete with the negatively charged sludge flocs for the positive charge of the coagulant AlCl3. By mixing fly ash with AlCl3 solution first, the fly ash mixes with the positively charged coagulant first, which is equivalent to directly neutralizing a part of the positive charge of the coagulant. This reduces the effectiveness of the coagulant after it enters the sludge and is not conducive to dewatering.

[0128] The capillary water absorption time, sludge specific resistance, bound water content, and dewatering rate of the conditioned sludge obtained from corresponding use cases 4 and 5 and comparative examples 4 and 5 were tested, and the results are as follows: Figure 5 As shown. By Figure 5 It can be seen that the modification reaction of TiCl4 solution and fly ash showed better modification effect at 0℃, specifically reflected in lower sludge specific resistance, bound water content, corrected capillary water absorption time and faster dehydration rate; while at room temperature, the modification effect of TiCl4 solution and fly ash was not good. This shows that the temperature control of the modification reaction is one of the important factors affecting the modification effect, which is different from simple room temperature mixing.

[0129] In addition, during the research and experimentation process, the inventors first conducted extensive research experiments on the effects of modification temperature and modification time on the dissolution of metal ions in the modification solution, and determined the modification conditions through experimental investigation. Some of the cases and test data are listed below, including:

[0130] Modified sludge dewatering conditioners were prepared according to the methods of Examples 1, 6-7, and Comparative Examples 6, 7-1 to 7-3. The concentrations of metal ions in the AlCl3 solution before the modification reaction and in the final modified solution were tested, and the relative concentrations of metal ions dissolved in the modified solution were calculated to investigate the effects of different modification temperatures and times on the relative concentrations of metal ions dissolved in the modified solution. The results are shown in Tables 3 and 4.

[0131] Table 3. Effect of reaction temperature on Al in the modified solution 3+ Ca 2+ Fe 3+ Mg 2+ Effect of relative dissolution concentration

[0132]

[0133] Table 4. Effect of reaction time on Al of the modified solution 3+ Effect of relative dissolution concentration

[0134]

[0135] As shown in Tables 3 and 4 above, in the modification reaction using AlCl3 solution and fly ash, as the temperature increases from 25℃ to 50℃, the Al... 3+ It still exhibits a dissolved state, but when the temperature rises to 80℃, Al 3+ It begins to exhibit an adsorption state, therefore the suitable modification reaction temperature is controlled between 25 and 50 °C. The reaction time is crucial for Al... 3+ The dissolution or adsorption of Al exhibits cyclical fluctuations, with Al at 1h and 2h. 3+ In the adsorption state, at 3 hours, Al3+ The solution is in a dissolution state at 12 hours, an adsorption state at 12 hours, and a dissolution state again at 24 hours. Therefore, reaction time is also an important influencing factor for the modification reaction, unlike simple mixing. Furthermore, under different conditions, Ca... 2+ Fe 3+ Mg 2+ The dissolution status did not change significantly, but all were in a dissolution state.

[0136] In addition, to examine the dewatering effect of the modified sludge dewatering conditioners prepared under the different conditions, the modified sludge conditioners prepared above were applied to sludge dewatering using the same sludge dewatering method as in Application Example 8, as follows:

[0137] Municipal sludge (from the same location but different batches as the municipal sludge in Application Examples 1, 4, 8, and 9, with a moisture content of 97.18%) was taken. The modified liquid from the modified sludge dewatering conditioner was added directly to the sludge, with the amount of modified liquid accounting for 5% of the dry weight of the concentrated sludge. The mixture was stirred at 200 r / min for 1 min. Subsequently, the modified solid phase from the modified sludge dewatering conditioner was added, with the amount of modified solid phase accounting for 10% of the dry weight of the concentrated sludge. The mixture was stirred at 200 r / min for 2 min, and then at 50 r / min for 15 min until it was uniformly mixed to obtain conditioned sludge. The conditioned sludge was then vacuum filtered at a fixed pressure of 0.07 MPa for 5 min. The sludge specific resistance and dewatering rate were measured and calculated. The results are shown in Table 5 below.

[0138] Table 5. Comparison of sludge dewatering effects of modified sludge dewatering conditioners prepared under different reaction conditions.

[0139]

[0140] As shown in Table 5 above, combined with Tables 3 and 4, the leaching of metal elements in the skeleton building agent that are similar to those in the chemical conditioner has a relatively greater effect on sludge dewatering. In Examples 1, 6, and 7, after modification treatment, the Al content in the modified solution... 3+ The relative concentration of dissolved substances is positive; compared to the initial reaction state, the Al concentration in the liquid phase is higher. 3+ Increased concentration, meaning that the Al element in the framework builder is in a dissolved state, plays a positive role in sludge dewatering. In comparative examples 6, 7-1, 7-2, and 7-3, after modification treatment, the Al content in the modified solution... 3+ The relative concentration of dissolved substances is negative, indicating that the Al concentration in the liquid phase is higher than that in the initial reaction state. 3+ Concentration decreases, i.e., Al 3+ The modified sludge dewatering conditioner is modified when the Al element in the skeleton building agent is in the adsorbed state, and the sludge dewatering effect is not as good as that of the modified sludge dewatering conditioner when the Al element is in the dissolved state.

[0141] Based on the above, in the modification reaction process, the reaction conditions are generally controlled so that the metal elements in the framework building agent that are the same as the metal elements contained in the chemical conditioner are in a dissolved state or the concentration of the metal ions corresponding to the metal elements contained in the chemical conditioner in the liquid phase is restored to the initial reaction state. It is preferable to control the metal elements in the framework building agent that are the same as the metal elements contained in the chemical conditioner to be in a dissolved state, so as to achieve effective modification of the liquid phase and increase the content of the metal ions corresponding to the metal elements in the chemical conditioner in the liquid phase.

[0142] Table 6. Effect of modified solid phase alone on sludge dewatering performance compared to unmodified solid phase.

[0143]

[0144] The conditioned sludge obtained from Example 8 and Comparative Example 8 was tested for capillary water absorption time, sludge specific resistance, bound water content, and dewatering rate. The results are shown in Table 6. As can be seen from Table 6, the use of modified solid phase alone also has a positive effect on sludge dewatering, specifically by correcting capillary water absorption time, reducing sludge specific resistance and bound water content, and increasing dewatering rate.

[0145] Table 7. Effects of static modification, unmodified sludge, and stirring modification on sludge dewatering performance.

[0146]

[0147] The conditioned sludge obtained from corresponding use case 9, application example 10, and comparative example 9 was tested for capillary water absorption time, sludge specific resistance, bound water content, and dewatering rate. The results are shown in Table 7. As can be seen from Table 7, static modification also plays a positive role in sludge dewatering, but its effect is not as great as that of stirring modification.

[0148] In addition, the inventors also used metal ion-containing framework building agents, such as silica fume and rice husk ash, to replace fly ash to prepare modified sludge dewatering conditioners in a similar manner as described above, and applied them to sludge dewatering. Experiments have verified that the modified sludge conditioners obtained after modification (including the mixed liquid obtained after the modification reaction, the modified liquid obtained by further solid-liquid separation, and / or the modified solid phase) can effectively improve the sludge dewatering level based on similar mechanisms.

[0149] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a modified sludge dewatering conditioner, characterized in that, Includes the following steps: The skeleton building agent and the chemical conditioner are modified in a medium solvent; the chemical conditioner is selected from at least one of acidic inorganic salt conditioners and acidic inorganic polymeric flocculants. The chemical conditioner contains a metal element, and the framework building agent contains the metal element; the temperature of the modification reaction is controlled above the dissolution temperature of the metal element in the framework building agent and below the decomposition temperature of the chemical conditioner; the time of the modification reaction is controlled when the metal element in the framework building agent is in a dissolved state or the concentration of the metal ion corresponding to the metal element in the liquid phase returns to the initial reaction state.

2. The preparation method of the modified sludge dewatering conditioner according to claim 1, characterized in that, The skeleton building agent is selected from at least one of fly ash, bottom ash, rice husk ash, silica fume, mineral powder, and red mud.

3. The preparation method of the modified sludge dewatering conditioner according to claim 1, characterized in that, The acidic inorganic salt conditioner is selected from at least one of acidic aluminum salt conditioner, acidic iron salt conditioner, and acidic titanium salt conditioner, and the acidic inorganic polymeric flocculant is selected from at least one of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, polyferric chloride, polyferric chloride sulfate, and polyphosphoric ferric chloride.

4. The preparation method of the modified sludge dewatering conditioner according to claim 1, characterized in that, The modification reaction of the skeleton builder and chemical conditioner in a medium solvent specifically includes: first dissolving the chemical conditioner in the medium solvent to obtain a chemical conditioner solution, and then adding the skeleton builder to carry out the modification reaction.

5. The preparation method of the modified sludge dewatering conditioner according to claim 4, characterized in that, The chemical conditioning agent contains a metal element, and the concentration of the metal ion corresponding to the metal element in the chemical conditioning solution is 400-600 mmol / L; the liquid-to-solid ratio of the chemical conditioning solution to the skeleton building agent is 3-10 mL / g.

6. The method for preparing the modified sludge dewatering conditioner according to any one of claims 1 to 5, characterized in that, After the modification reaction is completed, solid-liquid separation is performed, and the modified liquid and / or modified solid phase are taken to obtain the modified sludge dewatering conditioner.

7. A modified sludge dewatering conditioner, characterized in that, It is prepared by the method of any one of claims 1 to 6 for the preparation of the modified sludge dewatering conditioner.

8. The application of the modified sludge dewatering conditioner according to claim 7 in sludge dewatering.

9. A sludge dewatering method, characterized in that, Includes the following steps: S1. Add a modified sludge dewatering conditioner to the sludge for conditioning to obtain conditioned sludge; the modified sludge dewatering conditioner includes the modified sludge dewatering conditioner according to claim 7, or the modified sludge dewatering conditioner prepared by the preparation method of the modified sludge dewatering conditioner according to any one of claims 1 to 6. S2. Dewater the conditioning sludge.

10. The sludge dewatering method according to claim 9, characterized in that, In step S1, the modified sludge dewatering conditioner is the modified sludge dewatering conditioner prepared by the preparation method of the modified sludge dewatering conditioner according to any one of claims 1 to 5, and the amount of the modified sludge dewatering conditioner added is 2% to 10% of the dry weight of the sludge; or, in step S1, the modified sludge dewatering conditioner includes the modified sludge dewatering conditioner prepared by the preparation method of the modified sludge dewatering conditioner according to claim 6, the amount of the modified liquid added is 2% to 10% of the dry weight of the sludge, and the amount of the modified solid phase added is 5% to 20% of the dry weight of the sludge.

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