Method for recycling sludge

Abstract

The invention discloses a sludge resource reutilization method, and relates to the technical field of sludge resource and environment-friendly treatment.The method comprises the steps that original sludge is collected and pretreated; based on the pretreated original sludge, a sludge digestion nutrient solution and sludge solid residues obtained after anaerobic digestion are obtained through an efficient anaerobic digestion method; on the basis of a sludge digestion nutrient solution, microalgae breeding is carried out through an intelligent photobioreactor, and high-added-value dry fronds are obtained; the method comprises the following steps: on the basis of sludge solid residues after anaerobic digestion, performing magnetic nano material assisted separation and combining with a plate-and-frame filter press to obtain high-efficiency dehydrated solid residues; the high-performance multifunctional building material is prepared on the basis of the high-efficiency dehydrated solid residues and multifunctional auxiliary materials. According to the invention, through combination of efficient anaerobic digestion and the intelligent photobioreactor and combination of efficient dehydration treatment and multifunctional auxiliary materials, the growth rate and additional value of microalgae are improved, and comprehensive recycling of sludge is realized.

Description

Technical Field

[0001] The invention relates to the technical field of sludge resource utilization and environmental protection treatment, in particular to a method for sludge resource reuse. Background Art

[0002] With the acceleration of urbanization, sewage treatment and solid waste management have become key areas of environmental protection and resource recycling. As an inevitable byproduct of wastewater treatment, sludge treatment and resource recycling are becoming increasingly serious. Traditional sludge treatment methods such as incineration and landfilling not only cause environmental pollution and waste of resources, but also increase disposal costs. Therefore, finding efficient, environmentally friendly and economically beneficial sludge resource technology has become a research hotspot. Among the many sludge treatment technologies, anaerobic digestion technology is widely used in the field of sludge treatment due to its advantages such as efficient organic matter degradation, low energy consumption and renewable energy (biogas) recovery. At the same time, the selection and application of microalgae have also attracted the attention of academia and industry. Microalgae can not only effectively absorb nutrients in sludge through photosynthesis, but also achieve rapid growth in a short period of time, with high economic added value. Therefore, sludge resource methods based on microalgae have gradually become an innovative direction for future sludge treatment.

[0003] However, the existing technology still has some limitations in sludge resource utilization. First, the traditional sludge anaerobic digestion process has the problems of long treatment cycle and unstable treatment effect, especially when the sludge concentration is high, which often leads to poor digestion effect and even affects the subsequent resource recovery link. Secondly, although the breeding process of microalgae can effectively improve the conversion rate of nutrients in sludge, the current technology is mostly focused on a single photobioreactor design and microalgae screening, and lacks precise control of the microalgae growth environment. This makes the efficiency of microalgae reproduction low, and it is difficult to achieve stable and efficient algae production under different environmental conditions. Therefore, the existing sludge resource technology still faces problems such as low treatment efficiency, difficulty in resource recovery, and unclear economic benefits in practical applications. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method for recycling sludge resources to solve the problems of long treatment cycle in traditional anaerobic digestion process and lack of precise environmental control in microalgae breeding process.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for recycling sludge resources, which includes collecting raw sludge and pretreating the raw sludge; obtaining sludge digestion nutrient solution and sludge solid residue after anaerobic digestion through a high-efficiency anaerobic digestion method based on the pretreated raw sludge; propagating microalgae through an intelligent photobioreactor based on the sludge digestion nutrient solution to obtain high-value-added dry algae; based on the sludge solid residue after anaerobic digestion, obtaining high-efficiency dehydrated solid residue through magnetic nanomaterial-assisted separation combined with a plate and frame filter press; and preparing high-performance multifunctional building materials based on the high-efficiency dehydrated solid residue and multifunctional auxiliary materials.

[0008] As a preferred solution of the method for recycling sludge resources described in the present invention, the steps of collecting the original sludge and pre-treating the original sludge are as follows:

[0009] Raw sludge is collected from wastewater treatment plants and industrial outfalls;

[0010] The pretreatment of the raw sludge includes removing large particle impurities, crushing and homogenizing.

[0011] As a preferred embodiment of the method for recycling sludge resources described in the present invention, the sludge digestion nutrient solution and the sludge solid residue after anaerobic digestion are obtained by a high-efficiency anaerobic digestion method based on the pretreated original sludge. The specific steps are as follows:

[0012] Based on the pre-treated raw sludge, it is fed into a large anaerobic reactor through a screw pump to mix with anaerobic bacteria;

[0013] The large anaerobic reactor is heated by indirect steam heating, and the reaction temperature of anaerobic bacteria and pretreated raw sludge is adjusted in real time using PID. The expression is:

[0014]

[0015] Among them, T r (t+Δt) is the reaction temperature after adjustment at time step t+Δt, T m is the target temperature, T a (t) is the actual temperature at time step t, T a (τ) is the actual temperature at the time point τ of the integral variable, K p is the proportional control coefficient of PID, K i is the integral control coefficient of PID, K d is the differential control coefficient of PID, dτ is the small increment of the integral variable at time point τ, d(T m -T a(t)) is the instantaneous change in temperature difference, dt is the small increment of time step t, τ is the index variable of the time point of the integration variable, t is the index variable of the time step, and Δt is the time increment;

[0016] The pH value of the reaction between anaerobic bacteria and pretreated raw sludge is adjusted by lime water and sodium bicarbonate, and the expression is:

[0017]

[0018] Where pH(t+Δt) is the pH value after adjustment at time step t+Δt, [H + ]0 is the initial hydrogen ion concentration, k s is the proportional constant of the effect of alkaline substances on hydrogen ion concentration, ΔV l (t) is the volume of lime water to be added at time step t, ΔV n (t) is the volume of sodium bicarbonate to be added at time step t, V e is the volume of the large anaerobic reactor;

[0019] The VFA concentration was measured by gas chromatography, and the operating parameters of the large-scale anaerobic reactor were optimized according to the VFA concentration measurement results;

[0020] Based on the adjusted reaction temperature, adjusted pH value and optimized large-scale anaerobic reactor operating parameters, anaerobic bacteria gradually decompose organic matter in the pretreated raw sludge to obtain digestion products;

[0021] The digestion products are separated by sedimentation separation and mechanical dehydration to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion.

[0022] As a preferred embodiment of the method for recycling sludge resources described in the present invention, the digestion products are separated by a sedimentation separation method and a mechanical dehydration method to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion. The specific steps are as follows:

[0023] The digestion product is stirred by a mechanical stirrer to obtain a homogenized product;

[0024] The homogenized product is settled to the bottom by gravity in a sedimentation tank to form a solid waste residue and a clear liquid rich in nutrient solution which are initially separated;

[0025] The solid waste residue that is initially separated is initially dehydrated by high-speed rotation of a centrifugal dehydrator;

[0026] After sedimentation separation and mechanical dehydration, the sludge digestion nutrient solution and the sludge solid residue after anaerobic digestion are finally obtained.

[0027] As a preferred solution of the method for recycling sludge resources described in the present invention, wherein: based on the sludge digestion nutrient solution, microalgae are propagated through an intelligent photobioreactor to obtain high value-added dried algae, the specific steps are as follows:

[0028] The nutrient components in the sludge digestion nutrient solution were adjusted by the linear adjustment method to optimize the sludge digestion nutrient solution in the intelligent photobioreactor. The expression is:

[0029] N(t)=N0+s1·W+s2·(Y-Y0);

[0030] Wherein, N(t) is the nutrient concentration in the sludge digestion nutrient solution after optimization at time step t, N0 is the nutrient concentration in the initial sludge digestion nutrient solution, s1 is the proportional constant for adjusting the nutrient concentration in the sludge digestion nutrient solution, s2 is the proportional constant for the temperature effect, W is the effective nutrient volume in the sludge digestion nutrient solution, Y is the real-time temperature in the intelligent photobioreactor, and Y0 is the starting temperature in the intelligent photobioreactor;

[0031] Based on the optimized nutrient solution from sludge digestion, microalgae with the best growth rate are screened from the microalgae library by biological screening method;

[0032] The optimal growth rate microalgae and the optimized sludge digestion nutrient solution were inoculated, and the growth status of the optimal growth rate microalgae was evaluated in real time through the sensor in the intelligent photobioreactor. The calculation expression is:

[0033]

[0034] Among them, F(t) is the growth optimization score of the microalgae with the best growth rate at time step t, I(t) is the light intensity at time step t, α is the temperature sensitivity coefficient, and Y u is the optimal temperature in the intelligent photobioreactor, β is the photoperiod adjustment coefficient, 2πt is the position of time step t in the periodic change, G is the photoperiod, δ is the pH sensitivity coefficient, γ is a constant term, and pH ′ (t) is the current pH value, pH z ′ is the optimal pH value, η is the dissolved oxygen regulation coefficient, D(t) is the dissolved oxygen concentration at time step t, and D x is the target dissolved oxygen concentration, θ is the dissolved oxygen impact index;

[0035] Based on the growth optimization score, the growth status of the microalgae with the best growth rate was evaluated;

[0036] Based on the growth status evaluation results of the microalgae with the best growth rate, the microalgae are collected by membrane separation technology, and the collected microalgae are subjected to low-temperature drying technology to remove moisture, ultimately obtaining high-value-added dried algae.

[0037] As a preferred embodiment of the method for recycling sludge as a resource of the present invention, the growth state of microalgae with the best growth rate is evaluated based on the growth optimization score, and the specific steps are as follows:

[0038] Based on the historical growth optimization score, the ideal growth threshold Б is set by analyzing the growth performance of microalgae corresponding to different score intervals;

[0039] Evaluate the growth status of microalgae with optimal growth rate based on growth optimization score and ideal growth threshold;

[0040] When F(t)≥Б, it means that the growth state of the microalgae with the current optimal growth rate is very ideal;

[0041] When F(t)<Б, it means that the growth state of the microalgae with the current optimal growth rate is not ideal, and the environmental parameters need to be adjusted until F(t)≥Б.

[0042] As a preferred solution of the method for recycling sludge resources described in the present invention, the solid residue of sludge after anaerobic digestion is separated by magnetic nanomaterials and combined with a plate and frame filter press to obtain highly efficient dehydrated solid residue. The specific steps are as follows:

[0043] preparing the magnetic nanomaterial into magnetic nanomaterial particles by a ball milling method;

[0044] The magnetic nanomaterial particles are mixed with the solid residue of sludge after anaerobic digestion in an organic liquid by a liquid dispersion method to obtain a magnetic nano suspension;

[0045] The solid residue of sludge after anaerobic digestion adsorbing magnetic nanomaterials is separated from the magnetic nano suspension by a strong magnetic field in magnetic field separation to obtain magnetic nano sludge solid residue;

[0046] Using a plate and frame filter press to dehydrate the magnetic nano-sludge solid residue by mechanical pressure to obtain a dehydrated solid residue;

[0047] The moisture content of the dehydrated solid residue is further reduced by hot air drying to obtain a highly efficient dehydrated solid residue.

[0048] As a preferred solution of the method for recycling sludge resources described in the present invention, wherein: the high-performance multifunctional building materials are prepared based on the highly efficient dehydrated solid residue and multifunctional auxiliary materials, and the specific steps are as follows:

[0049] The composition of the solid residue from high-efficiency dehydration was analyzed by X-ray fluorescence spectrometry;

[0050] Based on the analysis results, highly efficient dehydrated solid residues with a high proportion of minerals are screened out;

[0051] Comprehensive performance testing and material screening methods are used to select multifunctional auxiliary materials with excellent performance from the candidate material library;

[0052] The high-quality dehydrated solid residue with high mineral content and the multifunctional auxiliary materials with good performance are mixed in mass proportion by high-speed stirring;

[0053] The mixed high-proportion mineral efficient dehydration solid residue and high-quality multifunctional auxiliary materials are molded using prefabricated molds and hydraulic pressure;

[0054] The formed building materials are cured at room temperature to ultimately produce high-performance multifunctional building materials.

[0055] In a second aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, any step of the method for sludge resource reuse as described in the first aspect of the present invention is implemented.

[0056] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the method for sludge resource reuse as described in the first aspect of the present invention is implemented.

[0057] The beneficial effects of the present invention are as follows: through the combination of efficient anaerobic digestion and intelligent photobioreactor, efficient treatment and resource utilization of sludge are achieved. First, the organic matter in the sludge is efficiently decomposed to generate biogas and nutrient solution through the optimized anaerobic digestion method, and the treatment efficiency is improved by precisely controlling the reaction temperature and pH value. Secondly, based on the sludge digestion nutrient solution, the intelligent photobioreactor is used to accurately control the growth environment of microalgae, thereby improving the growth rate and added value of microalgae. Finally, through the combination of efficient dehydration treatment and multifunctional auxiliary materials, the solid residue is converted into high-performance building materials, realizing the comprehensive resource utilization of sludge, which not only reduces the environmental burden, but also has significant economic benefits and market application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0059] Figure 1 This is a flow chart of a method for recycling sludge resources in Example 1.

[0060] Figure 2 This is a flow chart for obtaining highly efficient dehydrated solid residue in Example 1. DETAILED DESCRIPTION

[0061] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0062] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0063] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0064] Example 1, reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, provides a method for recycling sludge resources, comprising the following steps:

[0065] S1. Collect the original sludge and pre-treat it.

[0066] S1.1. Collect raw sludge from sewage treatment plants and industrial outfalls.

[0067] S1.2. Pretreatment of raw sludge includes removal of large particle impurities, crushing and homogenization.

[0068] It should be noted that the original sludge is pretreated by removing large particle impurities, crushing and homogenizing. The specific process is as follows:

[0069] Removal of large particle impurities: Through a series of screening equipment, such as coarse screens (for intercepting larger floating objects and suspended solids) and fine screens (for capturing smaller particulate matter), these devices are usually composed of metal bars or mesh structures, and objects with a diameter larger than the set value are screened out according to a predetermined aperture size. In addition, rotary screens or vibrating screens can also be used to effectively separate large particle impurities;

[0070] Crushing: After removing large particles of impurities, the sludge is sent to a specially designed crusher, which is equipped with high-speed rotating blades or shearing devices. When the sludge passes through, these mechanical components will exert strong shear and impact forces on larger sludge clumps, breaking them into smaller and more uniform particles.

[0071] Homogenization: The crushed sludge is then introduced into a mixing tank or agitator, which is equipped with a high-efficiency stirring device, such as a paddle stirrer or a turbine stirrer. Through continuous and uniform stirring action, sludge of different properties and concentrations can be fully mixed.

[0072] S2. Based on the pretreated original sludge, a high-efficiency anaerobic digestion method is used to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion.

[0073] S2.1, based on the pre-treated raw sludge, it is input into a large anaerobic reactor through a screw pump to mix with anaerobic bacteria.

[0074] S2.2. The large anaerobic reactor is heated by indirect steam heating, and the reaction temperature of the anaerobic bacteria and the pretreated raw sludge is adjusted in real time using PID. The expression is:

[0075]

[0076] Among them, T r (t+Δt) is the reaction temperature after adjustment at time step t+Δt, T m is the target temperature, T a (t) is the actual temperature at time step t, T a (τ) is the actual temperature at the time point τ of the integral variable, K p is the proportional control coefficient of PID, K i is the integral control coefficient of PID, K d is the differential control coefficient of PID, dτ is the small increment of the integral variable at time point τ, d(T m -T a (t)) is the instantaneous change in temperature difference, dt is the small increment of time step t, τ is the index variable of the integration variable time point, t is the index variable of the time step, and Δt is the time increment.

[0077] It should be noted that by referring to the best practice temperature range for anaerobic digestion, combined with factors such as sludge characteristics, reactor design and operating costs, one of the medium temperature (35-38°C) or high temperature (50-55°C) digestion ranges is selected as the target. Engineers will evaluate the effects of different temperatures on the activity of anaerobic bacteria, consider local climatic conditions, energy consumption and economic benefits, and ultimately determine a target temperature that can ensure efficient and economical sludge treatment.

[0078] S2.3, adjust the pH value of the reaction between anaerobic bacteria and pretreated raw sludge by lime water and sodium bicarbonate, the expression is:

[0079]

[0080] Where pH(t+Δt) is the pH value after adjustment at time step t+Δt, [H + ]0 is the initial hydrogen ion concentration, k s is the proportional constant of the effect of alkaline substances on hydrogen ion concentration, ΔV l (t) is the volume of lime water to be added at time step t, ΔV n (t) is the volume of sodium bicarbonate to be added at time step t, V e is the volume of the large anaerobic reactor.

[0081] S2.4. Determine the VFA concentration by gas chromatography and optimize the operating parameters of the large-scale anaerobic reactor based on the VFA concentration measurement results.

[0082] Furthermore, first, representative samples are collected from different locations of the large anaerobic reactor and immediately pretreated to remove solid particles and substances that may interfere with the analysis; then, the pretreated samples are injected into a gas chromatograph that has been calibrated and set with specific separation conditions (such as column temperature, carrier gas flow rate, etc.), the automatic injection program is started, and the peak area or height in the chromatogram is compared with the standard curve to accurately calculate the concentration of each VFA component; then, based on the measured VFA concentration data, it is compared with the pre-set optimal operating range to evaluate whether the operating parameters such as organic loading rate, pH value, temperature, etc. deviate from the ideal state - for example, if the VFA concentration increases abnormally, it indicates that there may be too high organic load or inappropriate pH value and temperature. At this time, measures should be taken to reduce the feed rate, adjust the pH to the ideal range of 6.5-7.5, and ensure that the temperature is stable in the range of 35-38℃ (medium temperature) or 50-55℃ (high temperature); finally, based on the above evaluation results, these operating parameters are continuously monitored and adjusted accordingly to ensure that the anaerobic reactor is maintained in an efficient and stable operating state.

[0083] S2.5. Based on the adjusted reaction temperature, adjusted pH value and optimized large-scale anaerobic reactor operating parameters, anaerobic bacteria gradually decompose the organic matter in the pretreated raw sludge to obtain digestion products.

[0084] Furthermore, by adjusting the reaction temperature and pH value of the anaerobic reactor and optimizing the operating parameters of the reactor, environmental conditions suitable for the growth and metabolism of anaerobic bacteria are created. Then, the anaerobic bacteria gradually decompose the organic matter in the pretreated raw sludge under this optimized environment. The process goes through multiple stages such as hydrolysis, acidification, hydrogen production, acetogenesis and methanogenesis: in the hydrolysis stage, complex organic matter (such as protein, fat, carbohydrate, etc.) is decomposed into simple soluble organic matter; in the acidification stage, part of the hydrolysis products are converted into short-chain fatty acids, hydrogen and carbon dioxide; then, hydrogen-producing bacteria and acetogenic bacteria further convert hydrogen and organic acids to generate acetic acid and other intermediate metabolites; finally, in the methanogenesis stage, methanogens convert intermediate products such as acetic acid and hydrogen into methane and carbon dioxide. After this series of biochemical reactions, other substances in the reactor (the part that is not converted into gas) are finally generated as digestion products.

[0085] Furthermore, the generated methane and carbon dioxide gases are usually collected by gas collection devices and sent to the biogas purification system for treatment. First, the methane and carbon dioxide gases are separated. Methane can be used as a renewable energy source for power generation, heating or conversion into other forms of energy, while carbon dioxide can be processed through adsorption or other technologies, and some can be used for industrial applications or safe discharge. Through this treatment method, methane gas can be effectively utilized and carbon dioxide can be managed through appropriate channels, thereby achieving maximum resource utilization and sustainable environmental protection.

[0086] S2.6. The digestion products are separated by sedimentation separation and mechanical dehydration to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion.

[0087] S3. Separate the digestion products by sedimentation separation and mechanical dehydration to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion.

[0088] S3.1. Stir the digestion product by a machine stirrer to obtain a homogenized product.

[0089] S3.2. The homogenized product is settled to the bottom of the sedimentation tank by gravity to form a preliminarily separated solid waste residue and a clear liquid rich in nutrient solution.

[0090] It should be noted that the homogenized mixture is introduced into the sedimentation tank, and the heavier solid particles are gradually settled to the bottom of the tank by gravity, forming a preliminarily separated solid waste layer; at the same time, the lighter liquid part, that is, the clear liquid rich in nutrients, remains in the upper layer. After a period of standing, the solid and liquid phases are fully separated, and the solid waste at the bottom can be regularly removed by mud discharge equipment, while the upper clear liquid is discharged through an overflow weir or a suction device.

[0091] S3.3. The solid waste residue that is initially separated is initially dehydrated by high-speed rotation of a centrifugal dehydrator.

[0092] It should be noted that the initially separated water-containing solid waste residue is continuously or intermittently input into the centrifugal dehydrator, and the strong centrifugal force generated by the high-speed rotation of the machine is used to quickly separate the solid matter and water; the heavier solid particles are thrown to the inner wall of the centrifuge casing and accumulate to form a solid residue layer, while the lighter water is discharged through the filter or sieve holes, realizing effective separation of solid and liquid; finally, the dehydrated solid residue is discharged from the specific outlet of the centrifuge.

[0093] S3.4. After sedimentation separation and mechanical dehydration, the sludge digestion nutrient solution and the sludge solid residue after anaerobic digestion are finally obtained.

[0094] S4. Based on the nutrient solution from sludge digestion, microalgae are propagated through intelligent photobioreactors to obtain high value-added dry algae.

[0095] S4.1. The nutrient components in the sludge digestion nutrient solution are adjusted by a linear adjustment method to optimize the sludge digestion nutrient solution in the intelligent photobioreactor. The expression is:

[0096] N(t)=N0+s1·W+s2·(Y-Y0);

[0097] Among them, N(t) is the nutrient concentration in the sludge digestion nutrient solution after optimization at time step t, N0 is the nutrient concentration in the initial sludge digestion nutrient solution, s1 is the proportional constant for adjusting the nutrient concentration in the sludge digestion nutrient solution, s2 is the proportional constant for the temperature effect, W is the effective nutrient volume in the sludge digestion nutrient solution, Y is the real-time temperature in the intelligent photobioreactor, and Y0 is the starting temperature in the intelligent photobioreactor.

[0098] It should be noted that nutrients mainly include nitrogen (N), phosphorus (P), potassium (K) and trace elements such as iron (Fe), manganese (Mn), zinc (Zn);

[0099] It should also be noted that the inorganic and small molecular organic compounds produced by the decomposition of raw sludge by microorganisms during the anaerobic digestion process, when complex organic substances, including proteins, nucleic acids, carbohydrates and lipids, are gradually degraded by anaerobic bacteria in an anaerobic environment, will release ammonia nitrogen (from proteins), phosphates (from nucleic acids and phospholipids) and other mineral elements. These components are dissolved into the digestive fluid as the organic matter decomposes, forming a sludge digestion nutrient solution rich in various nutrients.

[0100] S4.2. Based on the optimized sludge digestion nutrient solution, microalgae with the best growth rate are screened from the microalgae library through biological screening methods.

[0101] It should be noted that, first, different types of microalgae samples were inoculated into a culture medium containing the optimized sludge digestion nutrient solution, and cultured in parallel in a laboratory environment with controlled light, temperature, pH and other conditions; then, the growth rate, biomass yield and nutrient absorption efficiency of each microalgae sample in the nutrient solution were regularly monitored; based on the experimental data, those microalgae strains that showed the fastest growth rate and the highest nutrient utilization efficiency under the specified nutrient solution conditions were selected, and finally the microalgae with the best growth rate that was most suitable for the nutrient solution was determined.

[0102] S4.3. Inoculate the microalgae with the best growth rate and the optimized sludge digestion nutrient solution, and evaluate the growth status of the microalgae with the best growth rate in real time through the sensor in the intelligent photobioreactor. The calculation expression is:

[0103]

[0104] Among them, F(t) is the growth optimization score of the microalgae with the best growth rate at time step t, I(t) is the light intensity at time step t, α is the temperature sensitivity coefficient, and Y u is the optimal temperature in the intelligent photobioreactor, β is the photoperiod adjustment coefficient, 2πt is the position of time step t in the periodic change, G is the photoperiod, δ is the pH sensitivity coefficient, γ is a constant term, and pH ′ (t) is the current pH value, pH z ′ is the optimal pH value, η is the dissolved oxygen regulation coefficient, D(t) is the dissolved oxygen concentration at time step t, and D x is the target dissolved oxygen concentration, and θ is the dissolved oxygen impact index.

[0105] It should be noted that the light intensity is obtained by real-time monitoring through the light sensor installed in the intelligent photobioreactor;

[0106] The photoperiod refers to the time pattern of alternating light and darkness, which simulates the day and night changes in nature to adapt to the physiological rhythm of microalgae. It is obtained by a set of time parameters of alternating light and darkness executed by the automated control system of the intelligent photobioreactor.

[0107] The dissolved oxygen concentration is continuously measured inside the intelligent photobioreactor using a dissolved oxygen probe or electrode;

[0108] It should also be noted that the optimal temperature in the intelligent photobioreactor is obtained by experimentally studying the growth rate and biomass yield of microalgae at different temperatures, and finding the temperature range that promotes the most efficient photosynthesis and cell division, which is usually mesothermal (35-38°C) or hyperthermal (50-55°C);

[0109] Optimal pH value: Through experimental evaluation of the effects of different pH values ​​on the growth rate, nutrient absorption and metabolic activity of microalgae, a pH range that can maximize the productivity of microalgae and maintain system stability is determined, generally between 6.5 and 7.5. Online pH sensors are used for real-time monitoring and automatic adjustment agents (such as sodium bicarbonate or lime water) to finally obtain the optimal pH value;

[0110] The target dissolved oxygen concentration is determined by experimentally measuring the growth performance and health status of microalgae at different dissolved oxygen levels. A concentration is selected that can support the normal respiration of microalgae while avoiding excessive oxygen inhibiting its growth. It is usually close to saturation but not exceeding 100%. The target dissolved oxygen concentration is finally obtained through feedback control of the aeration system and dissolved oxygen sensor.

[0111] S4.4. Evaluate the growth status of microalgae with the best growth rate based on the growth optimization score.

[0112] S4.5. Based on the growth status evaluation results of the microalgae with the best growth rate, the microalgae are collected by membrane separation technology, and the collected microalgae are subjected to low-temperature drying technology to remove moisture, ultimately obtaining high-value-added dried algae.

[0113] It should be noted that the culture solution containing microalgae is pumped into a membrane filtration system equipped with a suitable pore size (usually 0.1 to 0.45 microns) through membrane separation technology. By applying a moderate pressure difference, liquids and small molecules are allowed to pass through the membrane, while larger microalgae cells are retained on the membrane surface or in the concentration zone, thereby obtaining concentrated microalgae;

[0114] The concentrated microalgae collected by the above-mentioned membrane separation technology are first frozen to an extremely low temperature (usually below -40°C). At this temperature, the water inside the microalgae is completely frozen into ice crystals. Next, it enters the sublimation stage under a vacuum environment. The ice crystals are directly sublimated from the solid state to gaseous water vapor through decompression. In order to ensure the drying efficiency and product quality, the entire freeze-drying process requires precise control of temperature, pressure and time parameters. In addition, in some cases, a staged heating method is used to gradually increase the temperature to accelerate the sublimation of water while avoiding damage to the cell structure of the microalgae. In the end, what is obtained is a high-value-added dried algae body that retains the original nutrients and bioactive substances.

[0115] S5. Based on the growth optimization score, the growth status of the microalgae with the best growth rate is evaluated.

[0116] S5.1. Based on the historical growth optimization score, the ideal growth threshold Б is set by analyzing the growth performance of microalgae corresponding to different score intervals.

[0117] It should be noted that the historical growth optimization score is first divided into multiple intervals, and then the average values ​​and changing trends of key indicators such as microalgae growth rate, biomass yield and environmental adaptability in each interval are statistically analyzed; then, statistical methods (such as correlation analysis or regression analysis) are used to evaluate the relationship between these indicators and the scores, and the score interval corresponding to the optimal growth conditions is identified. According to these analysis results, by comparing the performance of key indicators such as microalgae growth rate, biomass yield and environmental adaptability in different score intervals, the score interval with the best performance is identified, and the lower limit value of the optimal score interval is selected as the ideal growth threshold, or the average value of all scores in the interval is calculated as the threshold.

[0118] S5.2, evaluating the growth status of microalgae with the best growth rate based on the growth optimization score and the ideal growth threshold;

[0119] When F(t)≥Б, it means that the growth state of the microalgae with the current optimal growth rate is very ideal;

[0120] When F(t)<Б, it means that the growth state of the microalgae with the current optimal growth rate is not ideal, and the environmental parameters need to be adjusted until F(t)≥Б.

[0121] S6. Based on the solid residue of sludge after anaerobic digestion, magnetic nanomaterial-assisted separation is combined with a plate and frame filter press to obtain highly efficient dehydrated solid residue.

[0122] S6.1. Prepare magnetic nanomaterials into magnetic nanomaterial particles by ball milling.

[0123] Specifically, the initial magnetic material powder and an appropriate amount of hard grinding balls (such as stainless steel or zirconia balls) are added to a ball mill in a certain proportion, and then an appropriate process control agent (such as a surfactant or a solvent) is added. The ball mill is then sealed and placed on a ball mill for mechanical ball milling at a set speed and time. During the ball milling process, the high-energy collision and friction between the grinding balls cause the magnetic material to be continuously refined, and ultimately form uniformly dispersed magnetic nanomaterial particles.

[0124] S6.2. Mix the magnetic nanomaterial particles with the solid residue of sludge after anaerobic digestion in an organic liquid by a liquid dispersion method to obtain a magnetic nano suspension.

[0125] Specifically, the pre-prepared magnetic nanomaterial particles and the solid residue of sludge after anaerobic digestion are added to the selected organic solvent respectively; then, the liquid dispersion method (ultrasonic treatment or mechanical stirring, etc.) is used to fully disperse and evenly mix the two in the organic liquid to ensure that the magnetic nanoparticles are evenly attached to the surface of the sludge particles; finally, unbound impurities are removed by filtration or centrifugal separation to obtain a stable and evenly distributed magnetic nanosuspension.

[0126] S6.3. The solid sludge residue after anaerobic digestion with adsorbed magnetic nanomaterials is separated from the magnetic nano suspension by a strong magnetic field in magnetic field separation to obtain magnetic nano sludge solid residue.

[0127] Specifically, the magnetic nano-suspension is introduced into the area of ​​action of the strong magnetic field, and the responsiveness of the magnetic nano-materials to the magnetic field is utilized to make the solid sludge residue adsorbed with the magnetic nano-materials move rapidly toward the magnetic poles and gather; then, by physically removing or collecting these solid particles attracted by the magnetic field, effective separation from the liquid is achieved, and finally the magnetic nano-sludge solid residue is obtained.

[0128] S6.4. Dewater the magnetic nano-sludge solid residue by mechanical pressure using a plate and frame filter press to obtain a dehydrated solid residue.

[0129] Specifically, the magnetic nano-sludge solid residue is evenly distributed in the filter chamber of the plate and frame filter press, and the liquid is squeezed and discharged from the filter cloth by applying mechanical pressure, while the solid particles are trapped in the filter chamber to form a cake-like substance; after a period of high-pressure pressing, the water is removed to the greatest extent possible, and finally a dry and stable dehydrated solid residue is obtained.

[0130] S6.5. Further reduce the moisture content of the dehydrated solid residue by hot air drying to obtain a highly efficient dehydrated solid residue.

[0131] Specifically, the dehydrated solid residue after being treated by the plate and frame filter press is evenly spread in the drying equipment, and then an appropriate amount of hot air is introduced to accelerate the evaporation of water by utilizing the high temperature and airflow of the hot air; during the hot air drying process, the temperature and humidity are continuously monitored to ensure uniform heating and efficient dehydration; finally, an efficiently dehydrated solid residue with extremely low moisture content, dry and stable texture is obtained.

[0132] S7. Prepare high-performance multifunctional building materials based on highly efficient dehydrated solid residues and multifunctional auxiliary materials.

[0133] S7.1. Analyze the composition of the high-efficiency dehydration solid residue by X-ray fluorescence spectrometry.

[0134] Specifically, the dehydrated solid residue sample is ground into fine powder and pressed into tablets or directly prepared into a form suitable for testing; then, the sample is placed on the sample stage of the XRF spectrometer, and the instrument emits X-rays to irradiate the sample to stimulate the characteristic fluorescent X-rays of the elements in the sample; by detecting the energy and intensity of these characteristic X-rays, the XRF spectrometer can quickly and non-destructively determine the type and content of each element in the sample.

[0135] S7.2. Based on the analysis results, screen out highly efficient dehydrated solid residues with a high proportion of minerals.

[0136] Specifically, based on the elemental composition data provided by XRF, samples containing a higher proportion of minerals (such as silicon, calcium, iron, etc.) are identified; then, a threshold standard for the mineral content is set, and by comparing the analysis results of each sample, high-efficiency dehydrated solid residues that meet or exceed the standard are selected.

[0137] S7.3. Use comprehensive performance testing and material screening methods to select multifunctional auxiliary materials with excellent performance from the candidate material library.

[0138] Specifically, key performance indicators are determined based on application requirements (such as the required mechanical strength, thermal stability, chemical durability or specific functional requirements, etc.), and physical, chemical and mechanical properties tests are conducted on candidate materials to evaluate their performance under different conditions; the test results are combined with cost-benefit analysis, and the comprehensive performance of each candidate material is compared using material screening methods. Ultimately, those materials that perform well in all key indicators and are cost-effective are selected as multifunctional auxiliary materials.

[0139] S7.4. High-quality dehydrated solid residue with high mineral content and good performance multifunctional auxiliary materials are mixed in mass proportion by high-speed stirring.

[0140] Specifically, the optimal ratio is determined based on the desired final product performance, such as mechanical strength, chemical stability or specific functionality, and through preliminary tests and analysis. For example, if you want to enhance the mechanical strength of the composite material, you may choose a higher proportion of auxiliary materials; while if you focus on cost control, you may adjust to a higher proportion of solid residues;

[0141] The two materials are accurately weighed according to a predetermined mass ratio, added into a high-speed mixer, and stirred continuously for a certain period of time at a set speed to ensure that the two are fully and evenly mixed, and finally a composite material with stable performance is obtained.

[0142] S7.5. The mixed high-proportion mineral efficient dehydration solid residue and high-quality multifunctional auxiliary materials are molded by using prefabricated molds and hydraulic pressure.

[0143] Specifically, first, the uniformly mixed material is filled into a pre-designed mold; then, the mold filled with the material is placed in a hydraulic press and compression molded by set pressure and holding time; finally, after a certain curing or cooling process, the stability and strength of the molded part are ensured, thereby obtaining a finished component with a fixed shape and excellent performance.

[0144] S7.6. The formed building materials are cured at room temperature to produce high-performance multifunctional building materials.

[0145] Specifically, the formed material is placed in a humidity-controlled and well-ventilated environment and naturally cured at room temperature for a certain period of time. During this period, chemical cross-linking reactions or physical changes occur inside the material, gradually enhancing its structural stability and mechanical properties. After curing, a universal testing machine is used to test its compressive, tensile and flexural strength to ensure that it meets the design standards. Durability is evaluated through accelerated aging tests, such as weather resistance, resistance to freeze-thaw cycles and chemical corrosion resistance. Functional requirements, such as thermal conductivity, water absorption and fire resistance, are checked, and comprehensive testing is carried out using professional instruments and standardized testing methods to ensure that it meets the expected strength, durability and functional requirements, thereby obtaining high-performance multifunctional building materials.

[0146] This embodiment also provides a computer device, which is suitable for a method for resource recycling of sludge, including: a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement a method for resource recycling of sludge as proposed in the above embodiment.

[0147] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0148] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, a method for realizing sludge resource recycling proposed in the above embodiment is implemented; the storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (Static Random Access Memory, referred to as SRAM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), erasable programmable read-only memory (Erasable Programmable Read Only Memory, referred to as EPROM), programmable read-only memory (Programmable Red-Only Memory, referred to as PROM), read-only memory (Read-Only Memory, referred to as ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0149] In summary, the present invention achieves efficient treatment and resource utilization of sludge through: the combination of efficient anaerobic digestion and intelligent photobioreactor. First, the organic matter in the sludge is efficiently decomposed to generate biogas and nutrient solution through optimized anaerobic digestion method, and the treatment efficiency is improved by precisely controlling the reaction temperature and pH value. Secondly, based on the sludge digestion nutrient solution, the intelligent photobioreactor is used to accurately control the growth environment of microalgae, thereby improving the growth rate and added value of microalgae. Finally, through the combination of efficient dehydration treatment and multifunctional auxiliary materials, the solid residue is converted into high-performance building materials, realizing the comprehensive resource utilization of sludge, which not only reduces the environmental burden, but also has significant economic benefits and market application potential.

[0150] Example 2, referring to Table 1, is the second example of the present invention. To further verify the technical solution of the present invention, experimental simulation data of a method for recycling sludge resources is provided.

[0151] In order to verify the innovation and advantages of the present invention in the resource recycling of sludge, a series of experiments were designed to compare the effects of the prior art and the present invention at different treatment stages. The experiment was based on the original sludge collected from sewage treatment plants and industrial discharge ports, and pretreatment, anaerobic digestion, solid residue separation, microalgae reproduction and subsequent solid residue treatment were carried out according to the steps of the invention. Through this experiment, the differences between the traditional sludge treatment method and the optimization scheme proposed by the present invention in terms of digestion efficiency, nutrient solution utilization, microalgae growth rate, solid residue dehydration rate, etc. were compared.

[0152] First, the first step of the experiment is to collect raw sludge from sewage treatment plants and industrial discharge ports and pre-treat it. During the pre-treatment process, the raw sludge is screened through coarse and fine screens to remove large particles of impurities, then sent to the crusher for mechanical crushing, and homogenized by a high-efficiency stirring device to ensure that the sludge is evenly mixed, providing a good foundation for subsequent treatment.

[0153] Secondly, based on the pretreated sludge, a screw pump is used to input it into a large anaerobic reactor and mixed with anaerobic bacteria for anaerobic digestion. The temperature in the reactor is adjusted in real time by a PID temperature control system, and the pH value of the reaction system is adjusted by lime water and sodium bicarbonate to optimize the reaction environment. In this environment, anaerobic bacteria begin to decompose organic matter in the sludge and generate digestion products, including gases such as methane and carbon dioxide.

[0154] Next, the digestion products are separated in a sedimentation tank and a centrifugal dehydrator to obtain a clear liquid rich in nutrient solution and a solid residue of sludge after anaerobic digestion. High-quality microalgae are collected using membrane separation technology, and their growth conditions are optimized in an intelligent photobioreactor. Microalgae with the best growth rate are screened out by real-time monitoring and adjustment of parameters such as light, temperature, and pH. Finally, water is removed through low-temperature drying technology to obtain high-value-added dried algae.

[0155] Finally, after magnetic nanomaterial-assisted separation and plate-and-frame filter press dehydration, the water content of the sludge solid residue was further removed to obtain highly efficient dehydrated solid residue. Based on these dehydrated residues and multifunctional auxiliary materials, high-performance multifunctional building materials were prepared through component analysis, performance screening and mixing, providing a sustainable solution for the resource recycling of sludge.

[0156] The prior art specifically refers to traditional sludge treatment methods, such as conventional anaerobic digestion and physical and chemical treatment technologies.

[0157] The details are shown in Table 1 below:

[0158] Table 1 Sludge treatment comparison data table

[0159]

[0160]

[0161] The present invention is superior to the prior art in multiple key indicators. Compared with the traditional sludge treatment method, the pretreatment effect (large particle impurity removal rate) of the prior art is 72.3%, while the present invention is increased to 85.7%. The digestion efficiency (COD removal rate) is also significantly improved, from 78.5% to 90.1%. In addition, the present invention also shows better effects in VFA concentration and microalgae growth rate. The VFA concentration is increased from 1050.4 mg / L to 1287.6 mg / L, and the microalgae growth rate is increased from 0.42 g / L·d to 0.58 g / L·d, indicating that the present invention has a higher promoting effect on the cultivation and biodegradation process of microalgae. The dehydration rate of solid residue is also increased from 61.7% to 74.3%, reflecting the advantages of the present invention in resource recovery.

[0162] The present invention significantly improves the sludge treatment efficiency and resource utilization effect by optimizing the coupling process of anaerobic digestion and microalgae cultivation. Compared with the prior art, the present invention can effectively remove large particle impurities, improve COD removal rate, increase VFA concentration, and promote the rapid growth of microalgae, thereby improving the sludge degradation efficiency and energy recovery rate. At the same time, the present invention can also improve the dehydration rate of solid residues, achieve efficient dehydration and resource utilization of sludge, reduce treatment costs, and have good environmental and economic benefits.

[0163] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for recycling sludge, characterized in that: include, Collecting raw sludge and pre-treating the raw sludge; Based on the pre-treated raw sludge, a high-efficiency anaerobic digestion method is used to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion; Based on the nutrient solution digested by sludge, microalgae are propagated through intelligent photobioreactors to obtain high value-added dried algae. Based on the solid residue of sludge after anaerobic digestion, the highly efficient dehydrated solid residue is obtained by combining magnetic nanomaterial-assisted separation with a plate and frame filter press; High-performance multifunctional building materials are prepared based on highly efficient dehydrated solid residues and multifunctional auxiliary materials.

2. The method for recycling sludge as claimed in claim 1, characterized in that: The raw sludge is collected and pre-treated, and the specific steps are as follows: Raw sludge is collected from wastewater treatment plants and industrial outfalls; The pretreatment of the raw sludge includes removing large particle impurities, crushing and homogenizing.

3. The method for recycling sludge as claimed in claim 2, characterized in that: The method of obtaining sludge digestion nutrient solution and sludge solid residue after anaerobic digestion based on the pretreated original sludge by a high-efficiency anaerobic digestion method is specifically performed as follows: Based on the pre-treated raw sludge, it is input into a large anaerobic reactor through a screw pump to mix with anaerobic bacteria; The large anaerobic reactor is heated by indirect steam heating, and the reaction temperature of anaerobic bacteria and pretreated raw sludge is adjusted in real time using PID. The expression is: Among them, T r (t+Δt) is the reaction temperature after adjustment at time step t+Δt, T m is the target temperature, T a (t) is the actual temperature at time step t, T a (τ) is the actual temperature at the time point τ of the integral variable, K p is the proportional control coefficient of PID, K i is the integral control coefficient of PID, K d is the differential control coefficient of PID, dτ is the small increment of the integral variable at time point τ, d(T m -T a (t)) is the instantaneous change in temperature difference, dt is the small increment of time step t, τ is the index variable of the time point of the integration variable, t is the index variable of the time step, and Δt is the time increment; The pH value of the reaction between anaerobic bacteria and pretreated raw sludge is adjusted by lime water and sodium bicarbonate, and the expression is: Where pH(t+Δt) is the pH value after adjustment at time step t+Δt, [H + ]0 is the initial hydrogen ion concentration, k s is the proportional constant of the effect of alkaline substances on hydrogen ion concentration, ΔV l (t) is the volume of lime water to be added at time step t, ΔV n (t) is the volume of sodium bicarbonate to be added at time step t, V e is the volume of the large anaerobic reactor; The VFA concentration was measured by gas chromatography, and the operating parameters of the large-scale anaerobic reactor were optimized according to the VFA concentration measurement results; Based on the adjusted reaction temperature, adjusted pH value and optimized large-scale anaerobic reactor operating parameters, anaerobic bacteria gradually decompose organic matter in the pretreated raw sludge to obtain digestion products; The digestion products are separated by sedimentation separation and mechanical dehydration to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion.

4. The method for recycling sludge as claimed in claim 3, characterized in that: The digestion products are separated by sedimentation separation and mechanical dehydration to obtain sludge digestion nutrient solution and sludge solid residue after anaerobic digestion. The specific steps are as follows: The digestion product is stirred by a mechanical stirrer to obtain a homogenized product; The homogenized product is settled to the bottom by gravity in a sedimentation tank to form a solid waste residue and a clear liquid rich in nutrient solution which are initially separated; The solid waste residue that is initially separated is initially dehydrated by high-speed rotation of a centrifugal dehydrator; After sedimentation separation and mechanical dehydration, the sludge digestion nutrient solution and the sludge solid residue after anaerobic digestion are finally obtained.

5. The method for recycling sludge as claimed in claim 4, characterized in that: The method is based on sludge digestion nutrient solution, and microalgae are propagated through intelligent photobioreactor to obtain high value-added dry algae. The specific steps are as follows: The nutrient components in the sludge digestion nutrient solution were adjusted by the linear adjustment method to optimize the sludge digestion nutrient solution in the intelligent photobioreactor. The expression is: N(t)=N0+s1·W+s2·(Y-Y0); Wherein, N(t) is the nutrient concentration in the sludge digestion nutrient solution after optimization at time step t, N0 is the nutrient concentration in the initial sludge digestion nutrient solution, s1 is the proportional constant for adjusting the nutrient concentration in the sludge digestion nutrient solution, s2 is the proportional constant for the temperature effect, W is the effective nutrient volume in the sludge digestion nutrient solution, Y is the real-time temperature in the intelligent photobioreactor, and Y0 is the starting temperature in the intelligent photobioreactor; Based on the optimized nutrient solution from sludge digestion, microalgae with the best growth rate are screened from the microalgae library by biological screening method; The optimal growth rate microalgae and the optimized sludge digestion nutrient solution were inoculated, and the growth status of the optimal growth rate microalgae was evaluated in real time through the sensor in the intelligent photobioreactor. The calculation expression is: Among them, F(t) is the growth optimization score of the microalgae with the best growth rate at time step t, I(t) is the light intensity at time step t, α is the temperature sensitivity coefficient, and Y u is the optimal temperature in the intelligent photobioreactor, β is the photoperiod adjustment coefficient, 2πt is the position of time step t in the periodic change, G is the photoperiod, δ is the pH sensitivity coefficient, γ is a constant term, and pH ′ (t) is the current pH value, pH z ′ is the optimal pH value, η is the dissolved oxygen regulation coefficient, D(t) is the dissolved oxygen concentration at time step t, and D x is the target dissolved oxygen concentration, θ is the dissolved oxygen impact index; Based on the growth optimization score, the growth status of the microalgae with the best growth rate was evaluated; Based on the growth status evaluation results of the microalgae with the best growth rate, the microalgae are collected by membrane separation technology, and the collected microalgae are subjected to low-temperature drying technology to remove moisture, ultimately obtaining high-value-added dried algae.

6. The method for recycling sludge as claimed in claim 5, characterized in that: Based on the growth optimization score, the growth status of the microalgae with the best growth rate is evaluated. The specific steps are as follows: Based on the historical growth optimization score, the ideal growth threshold Б is set by analyzing the growth performance of microalgae corresponding to different score intervals; Evaluate the growth status of microalgae with optimal growth rate based on growth optimization score and ideal growth threshold; When F(t)≥Б, it means that the growth state of the microalgae with the current optimal growth rate is very ideal; When F(t)<Б, it means that the growth state of the microalgae with the current optimal growth rate is not ideal, and the environmental parameters need to be adjusted until F(t)≥Б.

7. The method for recycling sludge as claimed in claim 4, characterized in that: The solid residue of sludge after anaerobic digestion is separated by magnetic nanomaterials and combined with a plate and frame filter press to obtain highly efficient dehydrated solid residue. The specific steps are as follows: preparing the magnetic nanomaterial into magnetic nanomaterial particles by a ball milling method; The magnetic nanomaterial particles are mixed with the solid residue of sludge after anaerobic digestion in an organic liquid by a liquid dispersion method to obtain a magnetic nano suspension; The solid residue of sludge after anaerobic digestion adsorbing magnetic nanomaterials is separated from the magnetic nano suspension by a strong magnetic field in magnetic field separation to obtain magnetic nano sludge solid residue; Using a plate and frame filter press to dehydrate the magnetic nano-sludge solid residue by mechanical pressure to obtain a dehydrated solid residue; The moisture content of the dehydrated solid residue is further reduced by hot air drying to obtain a highly efficient dehydrated solid residue.

8. The method for recycling sludge as claimed in claim 7, characterized in that: The method of preparing high-performance multifunctional building materials based on highly efficient dehydrated solid residue and multifunctional auxiliary materials comprises the following specific steps: The composition of the solid residue from high-efficiency dehydration was analyzed by X-ray fluorescence spectrometry; Based on the analysis results, highly efficient dehydrated solid residues with a high proportion of minerals are screened out; Comprehensive performance testing and material screening methods are used to select multifunctional auxiliary materials with excellent performance from the candidate material library; The high-quality dehydrated solid residue with high mineral content and the multifunctional auxiliary materials with good performance are mixed in mass proportion by high-speed stirring; The mixed high-proportion mineral efficient dehydration solid residue and high-quality multifunctional auxiliary materials are molded using prefabricated molds and hydraulic pressure; The formed building materials are cured at room temperature to ultimately produce high-performance multifunctional building materials.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for recycling sludge as a resource according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for recycling sludge as a resource according to any one of claims 1 to 8 are implemented.

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