Sludge circulation treatment process capable of reducing pollution and carbon

Abstract

The invention relates to the technical field of sludge treatment, and discloses a sludge circulation treatment process capable of reducing pollution and carbon, which comprises the following steps: mixing secondary aluminum ash subjected to ball milling pretreatment, desulfurized gypsum dihydrate and light calcined magnesia with specific activity to prepare a solid composite conditioner; the conditioner is added into sludge, the pH value rising rate is controlled by utilizing the dissolution hysteresis characteristic of light calcined magnesia, a reaction system is driven to enable sludge extracellular polymers to be subjected to thermal wall breaking by utilizing aluminum ash hydrolysis heat at a low pH value stage, ettringite crystals are excited to grow at a high pH value stage, and a rigid framework is constructed; the problems that traditional sludge deep dehydration depends on an external heat source, energy consumption is high, and sludge flocs are wrapped by crystals too early due to strong base excitation are solved, and deep bound water release without the external heat source is achieved through kinetic decoupling of endogenous heat and crystal growth.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of sludge reduction and carbon reduction sludge recycling treatment process, belong to sludge treatment technical field. BACKGROUND

[0002] Current sludge is the product of sewage treatment process, which has both pollution source and resource attributes. The complex colloid structure formed by extracellular polymeric substance (EPS) locks a large amount of water in the form of bound water, making mechanical dewatering difficult, which restricts sludge reduction and resource utilization. Existing technologies often use inorganic flocculants or organic polymer conditioners to destroy the stability of colloids or introduce thermal drying and strong oxidation to break the wall to achieve deep dewatering. Based on the concept of waste treatment, industrial solid wastes such as aluminum ash and gypsum are used to co-treat sludge, taking into account cost advantages and resource recycling potential.

[0003] To solve the problem of deep dewatering of sludge, existing technologies attempt to seek breakthroughs from the perspective of biological and chemical regulation, trying to achieve reduction by optimizing microbial metabolic processes. For example, the Chinese invention patent with publication number CN120136391A discloses a sludge reduction and carbon reduction recycling treatment method, which selects dominant bacteria for sludge anaerobic digestion treatment, and uses the digestion leachate as a carbon source for wastewater treatment. Although this scheme achieves a certain degree of biochemical flow of organic matter, the technical route has inherent lag in kinetics: the microbial wall breaking and metabolic reaction are greatly affected by the environment and have a long cycle, and cannot form a burst impact force to break the strong binding of sludge colloids in a short time. Moreover, after simple enzymatic hydrolysis, the sludge flocs are still in a soft rheological state, lacking the rigid physical support of high-pressure squeezing, resulting in the closure of the pores in the subsequent mechanical dewatering link, making it difficult to discharge deep bound water and achieve deep reduction of the moisture content of the sludge cake. When using exothermic solid waste and mineral skeleton materials to co-treat sludge, existing technologies face the problem of kinetic matching. The thermal-induced wall breaking process of sludge extracellular polymeric substance requires sufficient heat accumulation and time lag to achieve full relaxation of the colloidal structure and release of bound water. The formation of mineral skeleton materials such as ettringite is an ionic rapid reaction that can easily burst into nucleation under conventional strong alkali activation conditions. The mismatch of physical and chemical processes in time sequence leads to the closure of the surface of the mineral crystal before the complete thermal wall breaking of the sludge flocs, forming a dense wrapping layer that hinders the discharge of internal bound water and the continuous infiltration of heat, making it difficult to achieve deep dewatering and reduction. The moisture content of the treated sludge cake is high, and there is a risk of heavy metal leaching.

[0004] Therefore, how to spontaneously achieve thermodynamic wall breaking and ordered kinetic decoupling of mineral crystal growth in the reaction system, ensure that the extracellular polymeric substance is fully broken and the bound water is released, and at the same time build a penetrating rigid drainage skeleton, to achieve low-energy consumption, high-efficiency deep dewatering of sludge and heavy metal solidification, has become a technical problem to be solved by the present application. SUMMARY

[0005] To solve the problems presented in the background art, the technical scheme of the present application is as follows: a sludge recycling treatment process for reducing pollution and carbon, comprising the following steps:

[0006] Step S1, conditioner preparation, mixing the ball-milled pretreated secondary aluminum ash, dihydrate desulfurization gypsum and light-burned magnesium oxide to prepare a solid composite conditioner; wherein the mass fraction of active metal aluminum in the secondary aluminum ash is 15% to 25%, the citric acid method activity of the light-burned magnesium oxide is 60s to 90s, and the particle size is 150 to 200 mesh;

[0007] Step S2, reaction wall breaking, adding the composite conditioner to the aqueous sludge to construct a reaction system under stirring conditions; using the dissolution characteristics of the light-burned magnesium oxide to control the pH value rising rate of the reaction system, so that the reaction system undergoes the following processes in order: in the stage when the pH value is below 9.0, the secondary aluminum ash hydrolyzes and releases heat, causing the thermal wall breaking of the sludge extracellular polymer; as the light-burned magnesium oxide continues to dissolve and the pH value rises above 10.5, the oxide film on the surface of the secondary aluminum ash breaks and the heat release is intensified, and at the same time, the dihydrate desulfurization gypsum reacts with the aluminum hydrolysis product in the sludge floc gap to generate a calcium aluminate crystal framework;

[0008] Step S3, pressure filtration dewatering, conveying the reacted sludge to a diaphragm filter press to discharge water through the pores formed by the calcium aluminate crystal framework under mechanical pressure, and obtaining a sludge cake.

[0009] Preferably, in step S1, the molar ratio of aluminum element, magnesium element and calcium element in the composite conditioner is 1:0.8:2.5 to 1:1.2:3.5; this ratio is used to maintain the alkalinity of the reaction system in the stage when the pH value is below 9.0, and to ensure that the amount of calcium aluminate crystals generated at the end of the reaction supports the skeleton structure of the sludge cake.

[0010] Preferably, the secondary aluminum ash is aluminum electrolysis waste residue or aluminum processing waste residue after denitrification and fluorine removal pretreatment; the particle size D50 of the secondary aluminum ash is 20 to 40 microns, so that the hydrolysis heat release rate of the aluminum ash matches the dissolution alkali production rate of the light-burned magnesium oxide; the mass content of dihydrate calcium sulfate in the dihydrate desulfurization gypsum is not less than 85%, and the chlorine ion content is less than 0.1%.

[0011] Preferably, in step S2, the stirring condition has a rotation speed of 40 to 60 rpm; the duration of the stage when the pH value is below 9.0 is 5 to 10 minutes; during this period, hydrogen bubbles generated by the reaction of the secondary aluminum ash with water form flow guiding micropores inside the sludge floc; when the pH value rises above 10.5, the system temperature rises to 55 to 70℃, and the duration is 10 to 15 minutes.

[0012] Preferably, the average pore size of the flow guiding micropores is 50-150 microns; when the pH value rises to above 10.5, the ettringite crystals grow along the gas-liquid interface of the flow guiding micropores to form tubular channels; the tubular channels maintain their shape during the pressure filtration in step S3, providing a flow guiding channel for the filtrate to drain.

[0013] Preferably, during the reaction in step S2, the heavy metal ions released from the sludge enter the ettringite crystal lattice structure during the growth of the ettringite crystal framework; the heavy metal ions include at least one of lead ions, cadmium ions or zinc ions.

[0014] Preferably, the mass of the light-burned magnesium oxide and the mass of the secondary aluminum ash in the composite conditioner satisfy the following defined mass activity matching relationship: wherein, is the mass of the light-burned magnesium oxide, is the mass of the secondary aluminum ash, is the citric acid method activity degree value of the light-burned magnesium oxide, in seconds, and 60 is a normalized reference constant, in seconds; the matching relationship is used to ensure that the aluminum ash hydrolysis heat generation occurs before the ettringite crystallization.

[0015] Preferably, in step S3, the pressure control mode of the diaphragm filter press is as follows: maintaining at a pressure of 0.6-0.8 MPa for 5-8 minutes to drain free water and compact the ettringite crystal framework; maintaining at a pressure of 1.5-2.0 MPa for 15-20 minutes to drain capillary water.

[0016] Preferably, it further includes step S4, post-processing: naturally stacking the mud cake obtained in step S3; using the heat generated by the hydrolysis of the residual secondary aluminum ash in the mud cake to maintain the mud cake temperature higher than the ambient temperature; the water content of the sludge is 95-98% and the organic matter content is 30-60%, which is municipal activated sludge; after the process treatment, the water content of the obtained mud cake is less than 50%.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] 1. In the sludge recycling process, specific hydrated active light burned magnesium oxide is selected as a slow-release excitation source, the pH is increased by dissolution, and the time gradient of thermodynamic wall breaking and mineral crystal growth is spontaneously constructed in a single reaction system; the pH induced window at the initial stage of dissolution makes the aluminum source component preferentially accumulate heat enthalpy by mild hydrolysis, drives the thermal relaxation and structure wall breaking of sludge extracellular polymer under low viscosity environment, and releases bound water; after the pH breakthrough nucleation threshold, explosive mineralization reaction occurs, and calcium aluminate crystals grow in situ between the broken flocs; endogenous timing control avoids the premature wrapping of unbroken flocs by crystals due to strong alkali instantaneous excitation, ensuring that the calcium aluminate skeleton penetrates and supports the sludge particles after deep wall breaking, and realizing deep mechanical separation of bound water without external heat source.

[0019] 2. A high permeability rigid multi-pore structure is constructed by using the synergistic mechanism of micro-gas generated by aluminum component hydrolysis and calcium aluminate crystal growth space; fine bubbles generated by aluminum hydrolysis at the initial stage of the reaction in situ pore-forming inside the relaxed sludge flocs form through fluid guiding channels; during the mineralization process, needle-shaped calcium aluminate crystals grow along the gas-liquid interface and interweave, solidifying the transient pore structure into incompressible permanent rigid channels; the 3D microskeleton grows from the inside to the outside, physically blocking the recovery of sludge colloid rheological properties, reducing the specific resistance of filter cake in the pressure filtration process, and enabling water to pass through the capillary channels between the rigid skeleton and be discharged under mechanical pressure, solving the engineering problem of sticky and easily clogged filter cloth after traditional reagent treatment.

[0020] 3. By using the synchronous coupling mechanism of extracellular polymer wall breaking release and calcium aluminate lattice growth, deep lattice solidification of heavy metal ions in sludge is realized; by using the kinetics path of wall breaking before crystallization, the heavy metal ions originally wrapped in the sludge extracellular polymer are released to the liquid environment with the destruction of the colloid structure, and are in the enrichment area of explosive growth of calcium aluminate crystals; the microscopic process improves the probability of heavy metal ions entering the calcium aluminate lattice structure through isomorphism, locks the free heavy metals into the mineral lattice, and inhibits the risk of heavy metal leaching in the natural environment after treatment, providing environmental safety guarantee for subsequent resource utilization of sludge. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The sludge recycling process flow chart coupled with thermal wall breaking and crystal skeleton construction of the present application;

[0022] Figure 2 The sludge dewatering efficiency and specific resistance characteristic comparison chart under different activity degrees of magnesium oxide of the present application;

[0023] Figure 3 The operation interaction and kinetic regulation logic diagram of the sludge treatment process of the present application;

[0024] Figure 4 The key process parameter and treatment effect data chart of each test group of Example 2 of the present application. DETAILED DESCRIPTION

[0025] In order to better understand the technical scheme of the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0026] The specific embodiment provides a sludge recycling treatment process for reducing pollution and carbon, which comprises a conditioner preparation step, a reaction wall breaking step, a filter pressing and dewatering step and a post-treatment step. In the conditioner preparation step, the ball-milled pretreated secondary aluminum ash, dihydrate desulfurization gypsum and light-burned magnesium oxide are mixed to prepare a solid composite conditioner. The secondary aluminum ash is selected from aluminum electrolysis waste residue or aluminum processing waste residue which has been pretreated by denitrification and fluorine removal. The particle size of the secondary aluminum ash is For to , the mass fraction of active metal aluminum is to , the mass content of dihydrate calcium sulfate in the dihydrate desulfurization gypsum is not less than , the chloride ion content is less than , the particle size of the light-burned magnesium oxide is to , and the citric acid method activity value is to , and the citric acid method activity value is determined according to the industry standard .

[0027] The molar ratio of aluminum element, magnesium element and calcium element in the composite conditioner is to , and the mass of the light-burned magnesium oxide and the mass of the secondary aluminum ash in the composite conditioner satisfy the mass activity matching relationship: , wherein is the mass of the light-burned magnesium oxide, is the mass of the secondary aluminum ash, is the citric acid method activity value of the light-burned magnesium oxide, and the unit is second, is a normalized reference constant, and the unit is second, the conditioner activity decay risk control procedure is that the relative humidity of the storage environment is , the environmental temperature is , the maximum effective residence time is , the pre-feeding detection is that the activity value of the mixed light-burned magnesium oxide is re-measured, , and the deviation of the initial calibration value should satisfy Due to the extremely strong hygroscopic and carbonization properties of lightly calcined magnesium oxide, materials exceeding the limit undergo micron-level stripping and regeneration or disposal treatment to prevent the formation of a magnesium hydroxide / magnesium carbonate passivation shell on the particle surface from interfering with the precise expression of dissolution lag kinetics. In the reaction cell-breaking step, a composite conditioner is added to the water-containing sludge, with the water-containing sludge having an initial moisture content. to Organic matter content to Municipal activated sludge, at a rotation speed of to The reaction system was constructed under stirring conditions, and the solubility characteristics of lightly calcined magnesium oxide were utilized to control the system. The rate of increase of the value causes the reaction system to undergo the following processes in sequence: Value lower than The phase lasts for a period of time. minutes to Within minutes, the secondary aluminum ash hydrolyzes and releases heat, causing thermal cell disruption of the extracellular polymers in the sludge.

[0028] During this period, hydrogen bubbles generated by the reaction of secondary aluminum ash and water form pores with an average diameter inside the sludge flocs. to The micropores that guide the flow, as the lightly calcined magnesium oxide continues to dissolve, allow for... Value rises to The oxide film on the surface of the secondary aluminum ash cracks, exacerbating the exothermic reaction and raising the system temperature to [a certain level]. to The duration is minutes to Minutes; simultaneously, the desulfurization gypsum dihydrate and aluminum hydrolysis products react in the gaps between sludge flocs to form an ettringite crystal framework. The ettringite crystals grow along the gas-liquid interface of the micropores, forming tubular channels. During the reaction, heavy metal ions released from the sludge enter the ettringite crystal lattice structure during the growth of the ettringite crystal framework. These heavy metal ions include at least one of lead, cadmium, or zinc ions. In the filter press dewatering step, the reacted sludge is transported to a diaphragm filter press. The pressure control method of the diaphragm filter press is as follows: to Maintain under pressure minutes to Minutes are spent draining free water and compacting the ettringite crystal framework; interstage pressing dynamics constraint: a linear ramp pressurization mode is adopted, with the derivative of the pressurization rate... Limited to Within the specified range, step-by-step hydraulic shocks are strictly prohibited to avoid sudden stress changes that could cause brittle collapse of the rigid ettringite microframework or instantaneous densification (skin effect) of the filter cake surface. This ensures that the deep capillary channels maintain topological connectivity and compressive stability in an increasing compressive stress field. to maintained under pressure minutes to minutes, water is discharged through the pores and tubular channels formed by ettringite crystal framework, and a mud cake is obtained, which has a water content of less than ; in the post-processing step, the mud cake is naturally stacked, and the heat generated by the hydrolysis of the secondary aluminum ash remaining in the mud cake is used to maintain the temperature of the mud cake higher than the ambient temperature.

[0029] Example 1: In a high-load operation scenario of a large municipal sludge treatment center with a daily treatment capacity of more than 500 tons, the organic matter content of the feed sludge fluctuates between to , and the water content is maintained at a high level of to for a long time. The objective technical obstacle faced by this working condition is that the colloid energy barrier constructed by sludge extracellular polymers limits the mechanical separation of water, resulting in a mud cake with a water content of about after traditional pressure filtration process, and the subsequent thermal drying process faces the challenges of high energy consumption and equipment corrosion. For this working condition, the sludge recycling treatment process for reducing pollution and carbon is adopted. In the preparation of the conditioner, a solid composite conditioner is prepared according to the properties of the sludge, and the activity value of the light burned magnesium oxide prepared by the citric acid method is calibrated in the interval of to to match the hydrolysis kinetics characteristics of the secondary aluminum ash. When the water-containing sludge and the composite conditioner are mixed to construct the reaction system, the dissolution lagging characteristics of the light burned magnesium oxide are used to maintain the system at an induction period of value less than for about minutes.

[0030] During this period, the mild hydrolysis reaction of the secondary aluminum ash releases a small amount of heat to cause thermal relaxation of the extracellular polymers, and the hydrogen gas bubbles generated in situ construct a micro-porous network with an average pore size of about in the sludge floc. As the light burned magnesium oxide accumulates and dissolves, the value of the system breaks through , the oxide film on the surface of the secondary aluminum ash breaks, and the reaction enters the explosion period. The released hydrolysis heat raises the temperature of the system to in minutes, which destroys the structure of the relaxed extracellular polymers and converts the bound water into free water. At the same time, dihydrate desulfurized gypsum and aluminum hydrolysis products grow into needle-shaped ettringite crystals along the gas-liquid interface in the gap of the floc with broken walls and rich micro-pores. The crystals interweave to construct a rigid three-dimensional micro-framework, which locks the free water in the framework gap and blocks the recovery of colloidal rheology. In the pressure filtration dewatering stage, the free water is discharged through low pressure pre-pressing, and After high-pressure pressing removes deep moisture, the resulting mud cake has a moisture content reduced to [missing value]. Furthermore, it exhibits a sandy, loose texture. Test results indicate that the leaching concentrations of lead and cadmium heavy metal ions in the mud cake are lower than those in the original mud. In summary, this embodiment verifies that by controlling the reaction kinetics timing, an orderly coupling of thermodynamic cell disruption and mineral framework construction can be achieved within a single system, thus solving the technical challenges of deep dewatering and heavy metal solidification of high-organic-matter sludge.

[0031] Example 2: This example aims to verify the actual effectiveness, rationality of key parameters, and synergistic effect of the pollution reduction and carbon reduction sludge recycling treatment process in the above specific embodiments under different light-burned magnesium oxide activity and dosage conditions. The experiment used mechanically dewatered sludge from a municipal wastewater treatment plant, with an initial moisture content of [missing information]. The organic matter content is , Value The experiment included the experimental group of this invention and three control groups. All experimental groups were subjected to the same ambient temperature (…). The process is carried out under stirring conditions, and the stirring speed is uniformly set to [value missing]. The sample of this invention uses a solid composite conditioner that meets the requirements of the aforementioned specific embodiments, wherein the citric acid activity value of lightly calcined magnesium oxide is [value missing]. Particle size is Mesh; secondary aluminum ash particle size for The active aluminum content is The mass ratio of lightly calcined magnesia to secondary alumina ash is set to satisfy the mass-activity matching relationship. The middle value, that is, take .

[0032] Control group 1 used highly active lightly calcined magnesium oxide, whose activity value using the citric acid method was [value missing]. The remaining conditions were the same as those of the sample group of this invention. This setup was designed to simulate the condition where the alkali production rate was too fast, leading to premature crystallization of ettringite. Control group 2 used low-activity light-calcined magnesium oxide, with a citric acid activity value of [value missing]. The remaining conditions were the same as those of the sample group of this invention. This setting was designed to simulate the working condition of insufficient heat production due to the lag in alkali production rate. The control group 3 conditioner did not contain light-burned magnesium oxide, but only used secondary aluminum ash and desulfurized gypsum dihydrate, and used sodium hydroxide to adjust the system. Value to The remaining conditions were the same as those of the sample group of this invention. This setup was designed to verify the irreplaceable role of lightly calcined magnesium oxide as a timing controller. During the experiment, the temperature of each reaction system was monitored in real time. The values ​​changed, and after the reaction was completed, the mixture was dehydrated by pressure filtration. The moisture content, specific resistance (SRF), and leaching toxicity of heavy metals in the cake were measured. Key experimental data were recorded as follows:Figure 4 as shown.

[0033] Data analysis shows that the sample group of the present application presents obvious two-stage characteristics of pre-induction and post-explosion, and the temperature rises to minutes of the induction period, The value is maintained at The system is slightly hot, and microbubbles can be observed under a microscope; the temperature rises sharply to minutes, The value corresponding to breaks through At this time, a large amount of needle-shaped ettringite is generated, and the moisture content of the final mud cake is as low as The specific resistance is greatly reduced, and the lead leaching concentration is far lower than the national standard, confirming the synergistic effect of the timing of heat wall breaking and lattice solidification; in contrast, the induction period of the control group 1 is only minutes due to the excessively high activity of magnesium oxide, and ettringite is generated in large quantities and wrapped around the floc before the floc is fully heat broken, hindering the subsequent hydrolysis of aluminum ash to generate heat (the maximum temperature is only ) and the release of internal moisture, resulting in deterioration of the dewatering effect; the reaction kinetics of the control group 2 is too slow due to the excessively low activity of magnesium oxide, and it cannot form a concentrated heat shock, so the wall breaking effect is poor; the control group 3 uses strong alkali excitation, and the induction period is , and the instantaneous nucleation of ettringite leads to a deadlock effect, the specific resistance of the mud cake is the highest, the dewatering is the most difficult, and the heavy metal solidification effect is the worst; in addition, to verify the rationality of the mass-activity matching relationship, the dosage of light-burned magnesium oxide is adjusted based on the sample group of the present application, so that the matching values are and The results show that when the matching value is , the system improvement is slow, and the heat generation peak value is reduced to , and the moisture content of the mud cake is ; when the matching value is , the reaction is too violent and uncontrollable, and part of the aluminum ash is wrapped before it is completely hydrolyzed, and the moisture content of the mud cake is .

[0034] Example 3: This example combines Figures 1 to 3 to explain a kind of pollution reduction and carbon reduction sludge recycling process, such as Figure 1 ​As shown, pre-treated secondary aluminum ash, desulfurized gypsum dihydrate, and lightly calcined magnesium oxide with specific activity were used as raw materials. These were mixed to prepare a solid composite conditioner, which was then added to the water-containing sludge. In the reaction system construction and kinetic control phase, the pH rise rate was controlled by utilizing the lag characteristic of lightly calcined magnesium oxide dissolution. This process was divided into two core stages: in the low pH stage, the thermal decomposition of aluminum ash hydrolysis drove the thermal disruption of extracellular polymers in the sludge; in the high pH stage, the growth of ettringite crystals was stimulated, constructing a rigid framework. This mechanism achieved the release of deep bound water without an external heat source and the decoupling of endogenous heat from crystal growth kinetics. Finally, the reacted sludge entered the mechanical filter press dewatering stage, where water was discharged through mechanical filtration, resulting in sludge cake.

[0035] like Figure 2 As shown, the horizontal axis represents the experimental groups and the activity of lightly calcined magnesium oxide, which are the sample group of this invention (75s), control group 1 (30s), control group 2 (150s), and control group 3 (no MgO), respectively. The left vertical axis is the moisture content of the mud cake (%), and the right vertical axis is the specific resistance of the mud cake. The graph shows a bar chart distinguishing between the moisture content (%) and the specific resistance of the mud cake. The sample group of this invention showed lower values ​​than the other three control groups in both the moisture content and specific resistance of the mud cake, while control group 3 had the highest values ​​in all categories. Figure 3 As shown in the figure, the interaction logic between the sludge treatment operator and the process system is presented. The operator sequentially performs operations such as mixing aluminum ash / gypsum / magnesium oxide, preparing solid composite conditioner, constructing reaction system, post-treatment of sludge cake, and performing filter press dewatering. During the construction of reaction system, the system correspondingly controls the rate of pH increase by utilizing the lag characteristics of MgO, and induces thermal cell disruption at low pH stage, and constructs ettringite crystal framework at high pH stage. Finally, during filter press dewatering, water is discharged through the framework pores.

[0036] Example 4: This example addresses the parameter black box problem identified in the above-mentioned comprehensive disclosure adequacy special diagnosis regarding the determination of the activity of light-burned magnesium oxide using the citric acid method in solid composite conditioners. It provides a standardized calibration and verification procedure to eliminate parameter uncertainties caused by differences in activity determination methods and conditions, ensuring that the present invention utilizes the dissolution lag characteristics of light-burned magnesium oxide to control... The reproducibility of the core technical characteristic of the rate of increase in value in engineering applications, the clear pretreatment standards of the test object, the selection of the light-burned magnesium oxide sample to be tested, and the placement of it in Drying in an oven After drying for several hours to remove adsorbed water, the sample was placed in a desiccator and cooled to room temperature. The sample was then sieved using a standard sieve, and particles with a diameter within a certain range were selected. At the end of the day Particles of varying sizes were used as test samples to eliminate the influence of particle size differences on dissolution kinetics; secondly, a standardized reaction test system was constructed, with a concentration of [missing information]. Citric acid solution was used as the reaction medium, and a measured amount was taken. The citric acid solution was placed in Add to the conical flask concentration Phenolphthalein ethanol indicator, place the conical flask on a thermostatic magnetic stirrer, and set the water bath temperature to [temperature value missing]. The stirring speed is kept constant. Once the solution temperature has stabilized, quickly add After pretreatment, the lightly calcined magnesium oxide sample was used, and a timer was started. Dynamic monitoring and endpoint determination were then performed. During stirring, the color change of the solution was closely observed. Because magnesium oxide reacts with citric acid, consuming acid, the solution color changes as the reaction progresses to a certain point. As the phenolphthalein indicator increases, the solution will turn a faint reddish hue. This procedure defines the reaction endpoint as: the first visible faint reddish hue appearing in the solution, and... If the color does not fade within seconds, record the time required from the addition of the sample to reaching this endpoint, in seconds. This is the citric acid activity value of the sample.

[0037] Finally, a mapping verification between activity and process parameters was established. To verify the correlation between the measured activity values ​​and the induction period duration in the process of this invention, three groups of lightly calcined magnesium oxide samples with different activities were prepared, and the measured values ​​were as follows: , and The three groups of samples were prepared into composite conditioners according to the proportions described in the aforementioned specific embodiments, and then applied to sludge of the same properties to carry out cell wall disruption reactions, with the reaction system being monitored in real time. Value changes, record The value increases from the initial value to The required time, data shows: activity level is The actual induction period of the sample was only Minutes, resulting in insufficient heat generation from aluminum ash hydrolysis; activity level is The actual induction period of the sample was extended to Minutes, resulting in low processing efficiency; while activity is The actual induction period of the sample was Minutes, falling within the requirements of this invention. to Within a minute range, the validation results established the activity values ​​for the citric acid method. to This parameter range is related to the induction period. to There is a deterministic nonlinear monotonic correspondence between the process effects within 1-10 minutes.

[0038] Example 5: To ensure the stability and effect reproduction of the sludge recycling treatment process of the present application under different batches of raw materials, diversified equipment specifications and complex environmental conditions, and to eliminate potential technical implementation risks, this embodiment provides a set of standardized offline parameter calibration and engineering debugging procedures. Through systematic pre-test, the optimal key process parameters are determined to ensure the reaction kinetics matching and treatment effect in the actual production process. For the core reaction driving component of light-burned magnesium oxide, based on the diverse sources and activity fluctuations with storage conditions, offline calibration of citric acid method activity is performed before each new batch of raw materials is put into the production line. Under standard laboratory conditions, a constant temperature magnetic stirring device is used to react the to-be-tested light-burned magnesium oxide sample with a predetermined concentration of citric acid solution, and the phenolphthalein indicator color change time is used as the activity index. If the measured value deviates from the target window of to , then the mixed sample's comprehensive activity needs to be adjusted by physically mixing magnesium oxide of different activity batches or adjusting its grinding fineness until the comprehensive activity falls within the standard range.

[0039] And for the heat and mass transfer differences of the reaction system under the actual engineering amplification effect, after formal production or equipment overhaul, the reaction thermokinetics baseline calibration needs to be performed. Using the pilot reaction kettle on the production line or the simulation device with the same stirring flow field characteristics, the standard ratio of sludge and composite conditioner is put in under the set stirring rate, and the dynamic change curve of the system temperature and value is monitored in real time. The time (induction period) from the initial point to to and the rate of temperature rise to the peak value are mainly investigated. If the induction period deviates from the set range of to minutes or the temperature rise peak value is lower than , then the composite conditioner dosage ratio or stirring rate needs to be adjusted until the expected thermokinetics baseline of the reaction is established. This calibration process ensures that the thermodynamic wall breaking and mineral skeleton building mechanisms can still be coupled under different engineering environments.

[0040] Example 6: This embodiment provides a set of standardized reaction thermokinetics parameter online self-adaptive calibration and control procedures for the process amplification effect and complex working condition adaptability problems identified in the above engineering black box list. By monitoring the key process variables in real time and adjusting the operating parameters, it is ensured that the core reaction kinetics characteristics of the present application can still be reproduced when the production scale and environmental conditions change. The dynamic setting logic of the benchmark parameters is clear. For the differences in organic matter content and initial temperature of different batches of sludge, a light-burned magnesium dosage correction model is established. According to the experimental data regression analysis, the correction coefficient is determined. With sludge organic matter content and initial temperature The functional relationship is ,in and This is an empirical constant; in actual operation, it is measured by the feed sludge. and Calculation Then, the baseline dosage determined in the specific implementation method is multiplied by This yields the actual dosage for the current batch of sludge.

[0041] Secondly, a real-time monitoring and feedback control closed loop for the reaction process is constructed, by installing multiple temperature sensors and online monitoring systems within the reactor. Plan, with Data is collected in seconds, and a temperature rise rate threshold is set. and Lag window After the reaction starts, the control system calculates the current rate of temperature rise in real time. If in hour This indicates that the reaction is too fast, and the system automatically reduces the stirring speed to [a certain value]. To suppress mass transfer; if in hour Still no breakthrough This indicates a reaction lag, and the system automatically increases the stirring speed to [a certain value]. And turn on auxiliary heating until... The leap control strategy dynamically adjusts physical field parameters to constrain the reaction trajectory to a preset path of induction followed by eruption. Finally, it executes a quantitative procedure that integrates endpoint determination and post-processing. This approach abandons the traditional method of using time as the sole endpoint and instead employs a dual-index coupled endpoint determination method, where the system decreases after simultaneously reaching its peak temperature. and The value stabilizes at The above continues When both conditions are met, the reaction is determined to be complete and the crystal lattice construction is completed, and the discharge command is automatically triggered.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A sludge recycling treatment process for reducing pollution and carbon emissions, characterized in that, Includes the following steps: Step S1, Conditioner preparation: Mix the pre-treated secondary aluminum ash, desulfurized gypsum dihydrate, and lightly calcined magnesium oxide to prepare a solid composite conditioner; wherein, the mass fraction of active metallic aluminum in the secondary aluminum ash is 15% to 25%, the citric acid activity of the lightly calcined magnesium oxide is 60s to 90s, and the particle size is 150 mesh to 200 mesh. Step S2, reaction cell disruption: The composite conditioner is added to the water-containing sludge, and a reaction system is constructed under stirring conditions. The pH rise rate of the reaction system is controlled by utilizing the solubility characteristics of lightly calcined magnesium oxide, so that the reaction system undergoes the following processes in sequence: In the stage where the pH value is below 9.0, the secondary aluminum ash hydrolyzes and releases heat, causing thermal cell disruption of the extracellular polymers in the sludge; as the lightly calcined magnesium oxide continues to dissolve and the pH value rises to above 10.5, the oxide film on the surface of the secondary aluminum ash ruptures and exothermics the reaction, while the dihydrate desulfurization gypsum and aluminum hydrolysis products react in the gaps between the sludge flocs to form an ettringite crystal framework; Step S3, filter press dewatering: The reacted sludge is transported to a diaphragm filter press, where water is discharged through the pores formed by the ettringite crystal framework under mechanical pressure, resulting in a sludge cake.

2. The sludge recycling treatment process for reducing pollution and carbon dioxide levels according to claim 1, characterized in that, In step S1, the molar ratio of aluminum, magnesium and calcium in the composite conditioner is 1:0.8:2.5 to 1:1.2:3.5; this ratio is used to maintain the alkalinity of the reaction system when the pH value is below 9.0, and to ensure that the amount of ettringite crystals generated at the end of the reaction supports the skeleton structure of the sludge cake.

3. The sludge recycling treatment process for pollution reduction and carbon reduction according to claim 1, characterized in that, Secondary aluminum ash is aluminum electrolysis waste residue or aluminum processing waste residue that has undergone denitrification and defluorination pretreatment; the particle size D50 of secondary aluminum ash is 20 micrometers to 40 micrometers, so that the hydrolysis heat generation rate of aluminum ash matches the dissolution alkali generation rate of lightly calcined magnesium oxide; the mass content of calcium sulfate dihydrate in dihydrate desulfurization gypsum is not less than 85%, and the chloride ion content is less than 0.1%.

4. The sludge recycling treatment process for pollution reduction and carbon reduction according to claim 1, characterized in that, In step S2, the stirring speed is 40 rpm to 60 rpm; the pH value is below 9.0 for 5 to 10 minutes; during this period, hydrogen bubbles generated by the reaction of secondary aluminum ash and water form flow-guiding micropores inside the sludge flocs; when the pH value rises to above 10.5, the system temperature rises to 55°C to 70°C for 10 to 15 minutes.

5. The sludge recycling treatment process for reducing pollution and carbon emissions according to claim 4, characterized in that, The average pore size of the flow-guiding micropores is 50 to 150 micrometers; when the pH value rises above 10.5, ettringite crystals grow along the gas-liquid interface of the flow-guiding micropores to form tubular channels; the tubular channels maintain their shape during the pressure filtration process in step S3, providing a flow channel for the discharge of filtrate.

6. The sludge recycling treatment process for pollution reduction and carbon reduction according to claim 1, characterized in that, During the reaction in step S2, heavy metal ions released from the sludge enter the crystal lattice structure of ettringite during the growth of the ettringite crystal framework; the heavy metal ions include at least one of lead ions, cadmium ions, or zinc ions.

7. The sludge recycling treatment process for reducing pollution and carbon dioxide levels according to claim 1, characterized in that, The mass of lightly calcined magnesium oxide added to the composite conditioner and the mass of secondary aluminum ash added satisfy the following defined mass activity matching relationship: ,in, For the quality of lightly calcined magnesium oxide, For the quality of secondary aluminum ash, , where is the citric acid activity value of lightly calcined magnesium oxide, in seconds, and 60 is the normalized reference constant, in seconds; this matching relationship is used to ensure that the heat generated by the hydrolysis of aluminum ash precedes the large-scale crystallization of ettringite.

8. The sludge recycling treatment process for reducing pollution and carbon emissions according to claim 1, characterized in that, In step S3, the pressure control method of the diaphragm filter press is as follows: maintain a pressure of 0.6MPa to 0.8MPa for 5 to 8 minutes to discharge free water and compact the ettringite crystal skeleton; maintain a pressure of 1.5MPa to 2.0MPa for 15 to 20 minutes to discharge capillary water.

9. The sludge recycling treatment process for reducing pollution and carbon dioxide levels according to claim 1, characterized in that, It also includes step S4, post-processing: the sludge cake obtained in step S3 is naturally piled up; the heat generated by the hydrolysis of the secondary aluminum ash remaining in the sludge cake is used to maintain the temperature of the sludge cake above the ambient temperature, and the water-containing sludge is an initial municipal activated sludge with a water content of 95% to 98% and an organic matter content of 30% to 60%. After processing, the resulting mud cake has a moisture content of less than 50%.

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