A process for reducing pollution and carbon sludge recycling

Abstract

The present application relates to the technical field of sludge treatment, and discloses a sludge recycling treatment process for reducing pollution and carbon, which comprises the following steps: mixing secondary aluminum ash, dihydrate desulfurization gypsum and light-burned magnesium oxide with a specific activity to prepare a solid-state composite conditioner; and adding the conditioner into sludge, using the slow dissolution characteristics of the light-burned magnesium oxide to control the pH value rising rate, driving the reaction system to first use the aluminum ash hydrolysis heat to make the sludge extracellular polymer heat breakage in the low pH value stage, and then exciting the calcium aluminate crystal growth and building a rigid skeleton in the high pH value stage; finally, water is discharged through mechanical pressure filtration, the present application solves the problems of high energy consumption of traditional sludge deep dewatering relying on external heat source and premature wrapping of sludge floc by crystals caused by strong alkali excitation, and realizes deep bound water release without external heat source through the kinetic decoupling of endogenous heat and crystal growth.

Description

Technical Field

[0001] This invention relates to a sludge recycling process for reducing pollution and carbon emissions, belonging to the field of sludge treatment technology. Background Technology

[0002] Sludge is a byproduct of wastewater treatment, possessing both pollutant and resource attributes. Its complex colloidal structure, composed of extracellular polymers, locks in a large amount of water as bound water, making mechanical dewatering difficult and hindering sludge reduction and resource utilization. Existing technologies often employ inorganic flocculants or organic polymeric conditioning agents to disrupt colloidal stability or introduce thermal drying and strong oxidation cell-wall breaking technologies to achieve deep dewatering. Based on the concept of treating waste with waste, the co-treatment of sludge using industrial solid wastes such as aluminum ash and gypsum can balance cost advantages with resource recycling potential.

[0003] To address the challenge of deep sludge dewatering, existing technologies attempt to break through from a biochemical regulation perspective, aiming to reduce sludge volume by optimizing microbial metabolic processes. For example, Chinese invention patent CN120136391A discloses a method for sludge recycling to reduce pollution and carbon emissions. This method involves screening dominant bacterial strains for anaerobic digestion of sludge and recycling the digestate as a carbon source for wastewater treatment. While this approach achieves some degree of organic matter biochemical transfer, its kinetics suffer from inherent stagnation: microbial cell disruption and metabolic reactions are highly dependent on environmental factors and have long cycles, failing to generate the explosive force needed to break the strong colloidal binding of sludge in a short time; furthermore, relying solely on enzymatic hydrolysis leaves the sludge flocs in a soft rheological state, lacking the rigid physical support to resist high-pressure pressing, hindering subsequent mechanical... The pores in the dewatering process are closed, making it difficult to remove deep bound water and achieve the required moisture content for deep volume reduction in the sludge cake. Existing technologies that utilize exothermic solid waste and mineral framework materials to co-treat sludge face challenges in kinetic matching. The thermally induced cell disruption process of sludge extracellular polymers requires sufficient enthalpy accumulation and time lag to fully relax the colloidal structure and release bound water. The formation of mineral frameworks such as ettringite is an ionic, rapid reaction that is prone to explosive nucleation under conventional strong alkaline conditions. The mismatch in the timing of physicochemical processes causes mineral crystals to close on the surface before the sludge flocs are fully thermally disrupted, forming a dense coating layer that hinders the removal of internal bound water and the continuous penetration of heat. This makes it difficult to achieve the required deep volume reduction in dewatering, resulting in a high rehydration rate and a risk of heavy metal leaching in the treated sludge cake.

[0004] Therefore, the technical problem to be solved by this invention is how to spontaneously decouple thermodynamic cell disruption and ordered kinetics of mineral crystal growth within the reaction system, ensuring that the extracellular polymer fully breaks down and releases bound water, while simultaneously constructing a pervasive rigid drainage framework to achieve low-energy consumption, high-efficiency deep dewatering of sludge and solidification of heavy metals. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: a sludge recycling treatment process for reducing pollution and carbon emissions, comprising the following steps:

[0006] 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.

[0007] 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;

[0008] 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.

[0009] Preferably, 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 in the stage where 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.

[0010] Preferably, the 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 the secondary aluminum ash is 20 micrometers to 40 micrometers, so that the hydrolysis heat generation rate of the aluminum ash matches the dissolution alkali generation rate of lightly calcined magnesium oxide; the mass content of calcium sulfate dihydrate in the desulfurized gypsum dihydrate is not less than 85%, and the chloride ion content is less than 0.1%.

[0011] Preferably, in step S2, the stirring speed is 40 rpm to 60 rpm; the duration of the stage with pH value below 9.0 is 5 minutes 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 minutes to 15 minutes.

[0012] Preferably, the average pore size of the flow-guiding micropores is 50 micrometers to 150 micrometers; when the pH value rises to 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.

[0013] Preferably, during the reaction process in step S2, the 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.

[0014] Preferably, 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 normalization 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.

[0015] Preferably, 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.

[0016] Preferably, the process 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 inside the sludge cake is used to maintain the temperature of the sludge cake above the ambient temperature; the water-containing sludge is municipal activated sludge with an initial water content of 95% to 98% and an organic matter content of 30% to 60%; after the process, the water content of the obtained sludge cake is less than 50%.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. In sludge recycling treatment, specific hydration-activated lightly calcined magnesium oxide is selected as a slow-release activation source. Utilizing the hysteresis kinetics of pH increase caused by dissolution, a time gradient of thermodynamic cell disruption and mineral crystal growth is spontaneously constructed within a single reaction system. The pH-induced window at the initial stage of dissolution allows aluminum source components to preferentially and mildly hydrolyze and accumulate enthalpy, driving thermal relaxation and structural disruption of sludge extracellular polymers under low viscosity conditions, releasing bound water. Explosive mineralization reaction occurs after the pH exceeds the nucleation threshold, allowing ettringite crystals to grow in situ between the disrupted flocs. Endogenous temporal control avoids the instantaneous activation of strong alkali, which could cause crystals to prematurely encapsulate undisrupted flocs, forming a water-locking effect. This ensures that the ettringite skeleton penetrates and supports the deeply disrupted sludge particles, achieving deep mechanical separation of bound water without the need for an external heat source.

[0019] 2. By utilizing the synergistic mechanism between the trace gas generated by the hydrolysis of aluminum source components and the growth space of ettringite crystals, a highly permeable rigid multi-level porous structure is constructed. In the initial stage of the reaction, the microbubbles generated by aluminum hydrolysis create pores in situ inside the relaxed sludge flocs, forming a through-flow fluid guiding channel. During the mineralization process, needle-like ettringite crystals grow and intertwine along the gas-liquid interface, solidifying the transient pore structure into an incompressible permanent rigid channel. The 3D micro-skeleton growing from the inside out physically blocks the recovery of sludge colloidal rheology, reduces the specific resistance of the filter cake during the pressure filtration process, and allows water to be discharged through the capillary channels between the rigid skeletons under mechanical pressure, solving the engineering problem of sticky sludge cake and easy clogging of filter cloth after traditional chemical treatment.

[0020] 3. By utilizing the synchronous coupling mechanism of extracellular polymer cell disruption and release with ettringite lattice growth, deep lattice solidification of heavy metal ions in sludge is achieved. A kinetic path of cell disruption followed by crystallization is adopted, where heavy metal ions originally encapsulated within the extracellular polymeric cells of the sludge are released into the liquid phase environment as the colloidal structure is destroyed, placing them in the explosive growth and enrichment zone of ettringite crystals. This microscopic process increases the probability of heavy metal ions entering the ettringite lattice structure through isomorphic substitution, locking free heavy metals within the mineral lattice and suppressing the risk of heavy metal leaching from the treated sludge cake under natural conditions, thus providing environmental safety assurance for the subsequent resource utilization of sludge. Attached Figure Description

[0021] Figure 1 This is a flow chart of the sludge recycling process of the present invention, which couples thermal cell disruption with crystal framework construction.

[0022] Figure 2 This is a comparison chart of sludge dewatering efficiency and specific resistance characteristics under different magnesium oxide activity levels according to the present invention;

[0023] Figure 3 This is a schematic diagram of the operation interaction and kinetic control logic of the sludge treatment process of the present invention;

[0024] Figure 4 The figures show the key process parameters and treatment effect data of each experimental group in Embodiment 2 of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] This specific embodiment provides a sludge recycling treatment process for reducing pollution and carbon emissions, including conditioning agent preparation, reaction and cell disruption, pressure filtration and dewatering, and post-treatment steps. In the conditioning agent preparation step, pre-treated secondary aluminum ash from ball milling, desulfurized gypsum dihydrate, and lightly calcined magnesium oxide are mixed to prepare a solid composite conditioning agent. The secondary aluminum ash is selected from aluminum electrolysis waste residue or aluminum processing waste residue that has undergone denitrification and defluorination pretreatment. The particle size of the secondary aluminum ash is... for to The mass fraction of active metallic aluminum is to The mass content of calcium sulfate dihydrate in desulfurized gypsum dihydrate is not less than Chloride ion content is lower than The particle size of lightly calcined magnesium oxide is At the end of the day The activity value of its citric acid method is as follows: to The activity values ​​of the citric acid method are based on industry standards. Measurement.

[0027] The molar ratio of aluminum, magnesium, and calcium in the compound conditioner is: to The addition mass of lightly calcined magnesium oxide and the addition mass of secondary aluminum ash in the composite conditioner satisfy the mass-activity matching relationship: ,in, For the quality of lightly calcined magnesium oxide, For the quality of secondary aluminum ash, The value represents the activity of lightly calcined magnesium oxide via the citric acid process, expressed in seconds. Normalized baseline constant, unit: seconds; Conditioner activity decay risk control procedure: relative humidity of storage environment. Ambient temperature Maximum effective stay time Pre-feeding testing: Retesting the activity of lightly calcined magnesium oxide after mixing. , compared with the initial calibration value The deviation must meet 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 Maintain under pressure minutes to Within minutes, water is drained through the pores and tubular channels formed by the ettringite crystal framework, resulting in a mud cake with a moisture content of less than [missing information]. In the post-processing step, the mud cake is piled up naturally, and the heat generated by the hydrolysis of the secondary aluminum ash remaining inside the mud cake is used to maintain the temperature of the mud cake above the ambient temperature.

[0029] Example 1: In a high-load operation scenario of a large municipal sludge treatment center with a daily processing capacity exceeding 500 tons, the organic matter content of the feed sludge is... to Fluctuations between, and the moisture content remained at a long-term level. to The high water content presents an objective technical obstacle in this operation: the colloidal energy barrier formed by the extracellular polymers in the sludge restricts the mechanical separation of water, causing the moisture content of the sludge cake after traditional filter press treatment to remain stagnant. The subsequent thermal drying process faces challenges of high energy consumption and equipment corrosion. To address this issue, this embodiment employs a pollution-reducing and carbon-reducing sludge recycling process. In the conditioner preparation stage, a solid composite conditioner is prepared based on the sludge properties. The activity value of lightly calcined magnesium oxide obtained using the citric acid method is calibrated at approximately [value missing]. to To match the hydrolysis kinetics of secondary aluminum ash, after the aqueous sludge and composite conditioner are mixed to construct the reaction system, the dissolution retardation characteristics of lightly calcined magnesium oxide are utilized to allow the system to... Value lower than The induction period lasts for approximately minute.

[0030] During this period, the mild hydrolysis reaction of secondary aluminum ash releases trace amounts of heat, causing thermal relaxation of the extracellular polymers. Simultaneously, the generated hydrogen bubbles construct in situ within the sludge flocs, creating pores with an average diameter of approximately [missing information]. The flow-guiding microporous network drives the system as lightly calcined magnesium oxide accumulates and dissolves. Value Breakthrough The oxide film on the surface of the secondary aluminum ash ruptures, and the reaction enters a rapid reaction phase, releasing heat of hydrolysis that raises the system temperature to [a certain level]. Rising to within minutes The thermal shock disrupts the relaxed extracellular polymer structure and converts bound water into free water. Simultaneously, in the interstices of the broken-cell and microporous flocs, needle-like ettringite crystals grow along the gas-liquid interface from the desulfurized gypsum dihydrate and aluminum hydrolysis products. These interwoven crystals form a rigid three-dimensional microframework, locking the free water within the framework interstices and preventing the recovery of colloidal rheology. During the pressure filtration dehydration stage, after… Low-pressure pre-pressurization discharges free water 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 this invention exhibits a clear two-stage characteristic of induction followed by outbreak, within approximately... During the 10-minute induction period, The value remains at The following system was slightly heated, and microbubbles were observed to form under a microscope; the temperature was within... Within minutes, it surged to ,correspond Value Breakthrough At this point, a large amount of needle-like ettringite was detected, and the final mud cake moisture content was as low as [missing information]. The resistivity was significantly reduced, and the lead leaching concentration was far below the national standard, confirming the temporal synergistic effect of thermal cell disruption and lattice solidification; in contrast, control group 1, due to excessively high magnesium oxide activity, only had an induction period of... Within minutes, ettringite is generated in large quantities and coats the sludge flocs before they are fully thermally broken down, hindering the subsequent heat generation from aluminum ash hydrolysis (maximum temperature only...). The release of internal moisture led to a deterioration in the dehydration effect. Control group 2, due to its low magnesium oxide activity and excessively slow reaction kinetics, failed to generate a concentrated thermal shock, resulting in poor cell disruption. Control group 3 utilized strong alkali activation, with an induction period of [missing information]. The instantaneous nucleation of ettringite leads to a deadlock effect, resulting in the highest specific resistance in the sludge cake, the most difficult dehydration, and the worst heavy metal solidification effect. Furthermore, to verify the rationality of the mass-activity matching relationship, the dosage of lightly calcined magnesium oxide was adjusted based on the sample group of this invention to achieve a matching value. They are respectively and The results showed that the matching value was At that time, the system The increase was slow, and the peak heat production decreased to The moisture content of the mud cake is Matching value At that time, the reaction was too violent and uncontrollable, and some aluminum ash was not completely hydrolyzed before being encapsulated, resulting in a mud cake with a moisture content of [missing information]. .

[0034] Example 3: This example combines Figures 1 to 3 A description of a sludge recycling process for reducing pollution and carbon emissions, such as... Figure 1As 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 minutes.

[0038] Example 5: To ensure the stable implementation and effect reproduction of the pollution reduction and carbon reduction sludge recycling treatment process of the present invention under different batches of raw materials, diverse equipment specifications, and complex environmental conditions, and to eliminate potential technical implementation risks, this example provides a standardized offline parameter calibration and engineering debugging procedure. Through systematic pre-testing, the optimal key process parameters are determined, thereby ensuring the reaction kinetics matching and treatment effect in the actual production process. For the core reaction-driving component, light-burned magnesium oxide, given its diverse sources and fluctuating activity with storage conditions, offline activity calibration using citric acid is performed before each new batch of raw materials is added to the production line. This requires reacting the light-burned magnesium oxide sample with a predetermined concentration of citric acid solution under standard laboratory conditions using a constant-temperature magnetic stirrer. The color change time of phenolphthalein indicator is used as the activity index. If the measured value deviates from the target value... to To determine the target window, it is necessary to physically mix batches of magnesium oxide with different activity levels or adjust its grinding fineness until the overall activity of the mixed sample falls within the standard range.

[0039] In addition, to address the differences in heat and mass transfer in the reaction system under actual engineering scale-up effects, a baseline calibration of the reaction thermodynamics must be performed after formal production or equipment overhaul. This involves using a pilot-scale reactor on the production line or a simulation device with the same stirring flow field characteristics, adding a standard ratio of sludge and composite conditioner at a set stirring rate, and monitoring the system temperature and... The dynamic change curve of the value is the focus of the examination. The value rises from the initial point to The time (induction period) and the rate at which the temperature rises to its peak value, if the induction period deviates from the peak value... to The set range or peak temperature rise within minutes is below If necessary, the addition ratio of the composite conditioner or the stirring rate needs to be fine-tuned until a baseline of thermo-chemical reaction kinetics that meets expectations is established. This calibration process ensures that the thermodynamic cell disruption and mineral skeleton construction mechanisms can still be coupled under different engineering environments.

[0040] Example 6: This example addresses the issues of process scale-up effects and adaptability to complex operating conditions identified in the aforementioned engineering black box list. It provides a standardized online adaptive calibration and control procedure for reaction thermodynamic parameters. By real-time monitoring of key process variables and feedback adjustment of operating parameters, it ensures that the core reaction kinetic characteristics of this invention can still be reproduced despite changes in production scale and environmental conditions. It clarifies the dynamic setting logic of benchmark parameters and establishes a correction model for the dosage of lightly calcined magnesium oxide based on differences in organic matter content and initial temperature of different batches of sludge. Based on regression analysis of experimental data, 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 benchmark 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 to obtain sludge cake; 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. 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 normalization 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.

2. The sludge recycling treatment process for reducing pollution and carbon dioxide levels 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%.

3. 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.

4. The sludge recycling treatment process for reducing pollution and carbon dioxide levels according to claim 3, 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.

5. 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.

6. The sludge recycling treatment process for pollution reduction and carbon reduction 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.

7. 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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