Method for treating tetracycline wastewater based on metal ion mediated sludge floc complexation

Abstract

This invention discloses a method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation, comprising: S1, taking trivalent metal ion mediator, sludge, and tetracycline wastewater in a certain proportion; S2, mixing the trivalent metal ion mediator, sludge, and tetracycline wastewater, stirring, and then letting it stand for 25-35 minutes to complete the treatment; the method of this invention utilizes heteroatoms on antibiotic molecules as electron donor sites for metal coordination. Under the mediation of trivalent metal ions, the two complex with sludge, thus efficiently removing tetracycline antibiotics from tetracycline wastewater, improving the selectivity and treatment efficiency for tetracycline in water, and providing an economical and efficient solution for the treatment of tetracycline wastewater.

Description

Technical Field

[0001] This invention relates to the field of tetracycline wastewater treatment technology, specifically to a method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation. Background Technology

[0002] While antibiotics serve as a crucial barrier against bacterial infections in modern society, their entry into the environment poses significant environmental and ecological risks. High concentrations of antibiotic residues, typically ranging from 44 to 1000 mg / L, are discharged during antibiotic production, forming antibiotic production wastewater. Such high antibiotic concentrations present a significant challenge to traditional activated sludge-based biological wastewater treatment. High antibiotic concentrations can affect the stable operation of activated sludge and increase the risk of antibiotic resistance gene transmission. Therefore, to ensure effluent safety, robust and effective physicochemical pretreatment at the upstream end of wastewater biological treatment is essential to alleviate antibiotic stress. For example, enhanced hot water hydrolysis and ozone oxidation strategies utilize the readily hydrolyzable nature of tetracycline to pretreat high-concentration production wastewater by enhancing the decomposition of tetracyclic antibiotics.

[0003] However, pretreatment strategies based on pollutant decomposition are energy-intensive processes, especially for high concentrations of pollutants. Complete removal or recovery of antibiotics from wastewater offers a promising alternative to energy-intensive pollutant decomposition processes. However, existing strategies such as physical adsorption and membrane filtration also require significant material investment and lack selectivity for antibiotics, resulting in relatively low efficiency. Therefore, a cost-effective and efficient method for treating antibiotics is lacking. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation.

[0005] A method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation includes the following steps:

[0006] S1. Take trivalent metal ion dielectric, sludge and tetracycline wastewater according to the proportion; wherein, the trivalent metal ion dielectric is a trivalent metal salt, and the amount of trivalent metal ion dielectric added satisfies formula (1):

[0007]

[0008] In the formula, x is the dosage of trivalent metal ion dielectric based on the mass of the metal element, in grams, and C is the concentration of tetracycline in the tetracycline wastewater, in g / m³. 3 V represents the volume of tetracycline wastewater, in cubic meters (m³). 3 , where a is the wastewater heterogeneity coefficient, which is dimensionless;

[0009] The amount of sludge added satisfies formula (2):

[0010] y = 235 × b × x (2);

[0011] In the formula, y is the amount of sludge added on a dry weight basis in g, b is the sludge ratio coefficient, which is dimensionless, and x is the amount of trivalent metal ion dielectric added on a metal element basis.

[0012] S2. Mix the trivalent metal ion dielectric, sludge and tetracycline wastewater, stir and let stand for 25-35 minutes to complete the treatment.

[0013] Explanation: The above method, through precise calculation of the amount of trivalent metal ion mediator and sludge added, can efficiently remove tetracycline antibiotics from tetracycline wastewater. This is because heteroatoms on antibiotic molecules can serve as electron donor sites for metal coordination. By utilizing heteroatoms on antibiotic molecules as electron donor sites for metal coordination, trivalent metal ions, such as Al... 3+ Under the mediation of the two, they coordinate and complex with the sludge, and trivalent metal ions (Al) 3+ / Fe 3+ This method mediates the efficient migration and solidification of antibiotics at the sludge humic acid floc interface. Therefore, using trivalent metal ions as a medium and sludge can improve the selectivity and treatment efficiency of tetracycline. The method is simple, reduces the risk of secondary pollution, and provides an economical and efficient solution for the treatment of tetracycline wastewater.

[0014] Furthermore, the trivalent metal ion is Al. 3+ or Fe 3+ The calculation method for x is: x = m × w%; where m is the mass of the trivalent metal salt and w% is the mass fraction of the metal element in the trivalent metal salt.

[0015] Note: The above method, by specifying the types of trivalent metal ions and providing calculation formulas, makes the operation more concrete and executable, ensuring accurate control of the dosage of metal ions in practical applications, thereby improving the efficiency and effectiveness of wastewater treatment. This clear guidance helps operators to precisely adjust parameters according to actual conditions when treating tetracycline wastewater, ensuring the stability and reliability of the treatment process.

[0016] Furthermore, the trivalent metal ion is Al. 3+ When the trivalent metal ion dielectric is any one of aluminum chloride, aluminum sulfate, or aluminum nitrate.

[0017] Note: The trivalent metal ion conductors listed above can all provide Al for the flocculation of tetracycline. 3+ .

[0018] Furthermore, the wastewater heterogeneity coefficient 'a' is related to the water quality of tetracycline wastewater. The more complex the water composition of tetracycline wastewater, the smaller 'a'; the simpler the water composition of tetracycline wastewater, the larger 'a'.

[0019] Note: Research has shown that the complexity of the aquatic environment affects the value of 'a'. This explanation helps operators adjust parameters according to the specific conditions of the wastewater, ensuring the accuracy and effectiveness of the treatment process. This is because other organic pollutants or metal ions present in the wastewater compete with tetracycline and Al. 3+ / Fe 3+ The complexation requires the addition of more trivalent metal salts.

[0020] Furthermore, the wastewater heterogeneity coefficient α ranges from 0.1 to 2.

[0021] Note: Setting the range of cedar trees allows for more precise adjustment and control of the wastewater treatment process, ensuring the stability and reliability of the treatment effect.

[0022] Furthermore, the sludge proportioning coefficient b was determined through preliminary experiments on tetracycline wastewater.

[0023] Note: Determining the b-value through preliminary experiments ensures that the amount of sludge added during actual treatment is more scientific and reasonable, thereby improving the efficiency and effectiveness of wastewater treatment.

[0024] Furthermore, the method for determining the sludge proportioning coefficient b includes:

[0025] First, take 200-400 mL of tetracycline wastewater with a concentration of C; add a trivalent metal ion dielectric with an addition amount of x to obtain a premix;

[0026] With the sludge proportioning coefficient b ranging from 0.01 to 1.4, multiple parallel experiments were set up, and sludge was added to the premix.

[0027] Then, the S2 operation is performed to obtain the treated tetracycline wastewater. The sludge ratio coefficient b corresponding to the set of parallel experiments with the highest tetracycline removal rate in the treated tetracycline wastewater is selected.

[0028] Note: The above method ensures that the selection of the b value is based on actual experimental data, thereby improving the scientificity and effectiveness of wastewater treatment, providing a replicable and optimized experimental method for similar wastewater treatment, and enhancing the reliability and operability of the treatment process.

[0029] Furthermore, the sludge is pretreated sludge from a water treatment plant. The pretreatment method is as follows: first, take the sludge from the water treatment plant and put it into water with a volume of 2 to 3 times that of the sludge. Let it stand and settle for 24 hours at a temperature of 4°C. Then, skim off the supernatant to obtain sludge, and store the sludge at a temperature of 4°C.

[0030] Note: The above method effectively removes impurities and excess water from the sludge through low-temperature settling and supernatant removal, improving the purity and activity of the sludge and ensuring its high efficiency and stability in subsequent wastewater treatment. At the same time, the low-temperature storage conditions also extend the service life of the sludge, providing a high-quality auxiliary material for wastewater treatment.

[0031] Furthermore, the mixing and stirring treatment of trivalent metal ion dielectric, sludge, and tetracycline wastewater described in S2 includes:

[0032] First, add sludge and trivalent metal ion dielectric to the tetracycline wastewater, and stir at 200-400 rpm for 25-35 seconds. Then, continue stirring slowly at 40 rpm for 4-5 minutes, and let it stand for 30-120 minutes to allow solid-liquid separation, thus completing the treatment.

[0033] Note: The staged stirring method described above, which mixes trivalent metal ion conductors, sludge, and tetracycline wastewater, helps to form a stable flocculent mixture, ensuring that the trivalent metal ion conductors and sludge can be uniformly dispersed in the wastewater, thereby improving the removal efficiency of tetracycline.

[0034] The beneficial effects of this invention are:

[0035] This invention utilizes the precise calculation of the addition amounts of trivalent metal ion mediators and sludge to efficiently remove tetracycline antibiotics from tetracycline wastewater. Because heteroatoms on antibiotic molecules can serve as electron donor sites for metal coordination, this method leverages heteroatoms on antibiotic molecules as electron donor sites for trivalent metal ions, such as Al... 3+ Under the mediation of the two, they coordinate and complex with the sludge, and trivalent metal ions (Al) 3+ / Fe 3+ This method mediates the efficient migration and solidification of antibiotics at the sludge humic acid floc interface. Therefore, using trivalent metal ions as a medium and sludge can improve the selectivity and treatment efficiency of tetracycline. The method is simple, reduces the risk of secondary pollution, and provides an economical and efficient solution for the treatment of tetracycline wastewater. Attached Figure Description

[0036] Figure 1The embodiments of the present invention show the removal of tetracycline wastewater with concentrations of 10(a), 50(b), and 200 mg / L(c) and the content of residual Al in the water (d, e, f).

[0037] Figure 2 This is an example of the ligand characteristics of tetracyclic antibiotics in this invention and Al. 3+ - The removal effect of sludge on the interface;

[0038] Figure 3 This invention relates to the effect of sludge centrifugal dewatering on the stability of TC solidification in embodiments of the present invention.

[0039] Figure 4 The sludge dewatering properties in the embodiments of the present invention vary with Al. 3+ Changes in the amount added;

[0040] Figure 5 The variations of Zeta potential (a) and particle size (b) of mud flocs with Al dosage in embodiments of the present invention are shown.

[0041] Figure 6 This invention relates to Al under complex water quality conditions in embodiments of the present invention. 3+ Mediating the removal of TC(a,b), COD(c) and TP(d) by sludge;

[0042] Figure 7 The economic cost (a) and carbon footprint (b) of the hot water hydrolysis, ozone oxidation and Al-WS pretreatment in the embodiments of the present invention are shown.

[0043] Figure 8 The method provided by this invention is illustrated in the complete process diagram. Detailed Implementation

[0044] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0045] Based on the background technology, this study found that wastewater biological treatment processes continuously generate byproducts, namely residual activated sludge. This residual activated sludge typically has a floc size of 10-100 μm and a large specific surface area. Furthermore, the outer layer of activated sludge is coated with multiple layers of extracellular polymeric substance (EPS), which inherently possesses a certain degree of bioflocculation function. The EPS interface of wastewater sludge can effectively adsorb and enrich pollutants, thus creating conditions for the efficient degradation of pollutants by microorganisms within the sludge flocs. This interfacial effect also makes wastewater sludge an important sink for antibiotics. The idea is to directly bind antibiotics to the EPS interface of residual sludge, removing them without further biodegradation. Currently, the insufficient binding capacity and selectivity of sludge interfaces for high concentrations of antibiotics limits the realization of this concept.

[0046] Furthermore, heteroatoms on antibiotic molecules can serve as electron donor sites for metal coordination. 3+ The unique coordination-induced fluorescence response with tetracycline (TC) visualized the complexation of the antibiotic with the metal. Furthermore, trivalent metal ions (Al...) 3+ / Fe 3+ This invention mediates the efficient migration and solidification of antibiotics at the humic acid floc interface. The metal coordination properties of antibiotics provide new possibilities for the selective solidification of antibiotics at the sludge interface. Utilizing the ligand characteristics of antibiotics, under the mediation of trivalent metals, it is expected to achieve efficient and selective fixation of antibiotics at the sludge interface. This can be further verified in the scenario of antibiotic wastewater pretreatment, while solving the problem of pretreatment of high-concentration antibiotic wastewater. Therefore, the embodiments of this invention specifically verify the Al 3+ The effectiveness of sludge interfacial complexation in the pretreatment of high-concentration tetracycline antibiotic wastewater was investigated, and the effects of TC-Al were further revealed. 3+ - The microscopic interfacial molecular interaction mechanism and reaction thermodynamic characteristics of the ternary sludge system were investigated. Furthermore, the overall performance of the novel pretreatment process in a complete wastewater-sludge treatment system was evaluated; details are as follows:

[0047] Example 1: A method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation, comprising the following steps:

[0048] S1. Take trivalent metal ion dielectric, sludge and tetracycline wastewater according to the proportion; wherein, the trivalent metal ion dielectric is a trivalent metal salt, and the amount of trivalent metal ion dielectric added satisfies formula (1):

[0049]

[0050] In the formula, x is the dosage of trivalent metal ion dielectric based on the mass of the metal element, in grams, and C is the concentration of tetracycline in the tetracycline wastewater, in g / m³. 3 V represents the volume of tetracycline wastewater, in cubic meters (m³). 3 , where a is the wastewater heterogeneity coefficient;

[0051] The amount of sludge added satisfies formula (2):

[0052] y = 235 × b × x (2);

[0053] In the formula, y is the amount of sludge added on a dry weight basis in g, b is the sludge ratio coefficient, and x is the amount of trivalent metal ion dielectric added on a metal element basis.

[0054] The trivalent metal ion is Al 3+ The calculation method for x is: x = m × w%; where m is the mass of the trivalent metal salt, w% is the mass fraction of the metal element in the trivalent metal salt, and the trivalent metal ion dielectric is aluminum chloride.

[0055] The wastewater heterogeneity coefficient α is related to the water quality of tetracycline wastewater. The more complex the water quality composition of tetracycline wastewater, the smaller α is; the simpler the water quality composition of tetracycline wastewater, the larger α is. The wastewater heterogeneity coefficient α ranges from 0.1 to 2. In this embodiment, α is 0.74.

[0056] The sludge ratio coefficient b is determined through preliminary experiments on tetracycline wastewater. The method for determining the sludge ratio coefficient b includes: first, taking 200-400 mL of tetracycline wastewater with a concentration of C; adding a trivalent metal ion dielectric in an amount of x to obtain a premix; setting up multiple parallel experiments with the sludge ratio coefficient b ranging from 0.01 to 1.4, and adding sludge to the premix; then performing operation S2 to obtain treated tetracycline wastewater, and selecting the sludge ratio coefficient b corresponding to the parallel experiment with the highest tetracycline removal rate in the treated tetracycline wastewater. In this embodiment, the value of the sludge ratio coefficient b is 0.425.

[0057] The sludge is pretreated sludge from a water treatment plant. The pretreatment method is as follows: first, take the sludge from the water treatment plant and put it into water with a volume of 2 to 3 times that of the sludge. Let it stand and settle for 24 hours at a temperature of 4°C. Then, skim off the supernatant to obtain the sludge. The sludge is stored at a temperature of 4°C.

[0058] Sludge samples were taken from the wastewater treatment plant of a certain city's wastewater treatment company, specifically from the sludge storage tank connected to the secondary sedimentation tank. The plant's secondary biological treatment section uses a traditional A / A / O process, with an average treatment capacity of 365,000 tons / day. After sampling, the sludge was allowed to settle at 4℃ for 24 hours. The supernatant was then removed to obtain further concentrated sludge. The concentrated sludge was stored in a light-protected 4℃ cold storage and used immediately after collection. The properties of the concentrated sludge are shown in Table 1 below.

[0059] Table 1 Properties of sludge samples

[0060]

[0061] S2. Mix the trivalent metal ion dielectric, sludge and tetracycline wastewater, stir and let stand for 25-35 minutes to complete the treatment.

[0062] The mixing and stirring treatment of trivalent metal ion dielectric, sludge, and tetracycline wastewater described in S2 includes:

[0063] First, sludge and trivalent metal ion mediators are added to the tetracycline wastewater. The mixture is stirred at 300 rpm for 30 seconds, then slowly stirred at 40 rpm for 4.5 minutes. Finally, the mixture is allowed to settle for 50 minutes to separate the solid and liquid phases, thus completing the treatment.

[0064] For example, in this scheme, the volume of tetracycline wastewater is V = 400 mL, the concentration of tetracycline is C = 200 mg / L, the wastewater heterogeneity coefficient a is 0.74, the sludge ratio coefficient b is 0.425, and the calculated dosage of aluminum chloride (based on Al mass) x is 0.008 g, and the sludge dosage y based on dry weight is 2 g.

[0065] Based on the present invention, the following experimental results demonstrate the effectiveness of this solution:

[0066] I. Mechanism and Effect Demonstration Experiments:

[0067] ① The experimental steps of the present invention for coordination-mediated removal of antibiotics from sludge include: preparing a 400 mg / L tetracycline (TC) stock solution and a 2 g / L Al solution. 3+ Aluminum chloride (ACH) stock solution was prepared, and a sludge sample was added to obtain a sludge-TC mixture at the set concentration. Specifically, sludge-TC mixtures with set concentrations of 10, 50, and 200 mg / L and sludge concentrations of 2, 5, and 10 g TSS / L were prepared to obtain sludge-TC mixtures with a total volume of 400 mL. ACH was then added to the mixture. 3+The stock solution was rapidly stirred on a magnetic stirrer for 30 seconds (stirring speed 300 rpm / min) to ensure thorough mixing under vigorous hydraulic conditions, followed by slow stirring for 4.5 minutes (40 rpm / min) to allow the sludge flocs to grow under gentle hydraulic conditions. The total reaction time was 5 minutes. After stirring, the mixture was allowed to stand for 30 minutes to allow the sludge flocs to settle completely. After settling, the supernatant was collected using a syringe and filtered through a 0.45 μm filter to obtain a liquid sample. The pH was tested, and the sample was analyzed to determine chemical indicators such as TC concentration, dissolved organic carbon, and residual Al.

[0068] Furthermore, in other experimental cases of this invention, when simulating experiments under complex water quality conditions, a simulated mother liquor containing conventional pollutants is synthesized using skim milk powder, starch, sodium acetate, sodium dihydrogen phosphate, and ammonium chloride (in a mass ratio of 6:1:1:1.1:0.335). This mother liquor is then mixed with TC stock solution and diluted to a COD (chemical oxygen demand) of 4500 mg / L, at which point the dissolved COD is 3563 mg / L. This is used to simulate antibiotic wastewater under complex water quality conditions. The above experimental steps are repeated for the synthesis of coordination-mediated sludge removal of antibiotics under complex water quality conditions.

[0069] ② First, an ultrafiltration experiment was used to obtain EPS (extracellular polymeric substances) solution samples to characterize the mechanism of tetracycline adsorption by sludge; specifically, sludge efficiently adsorbs tetracycline through EPS on its surface.

[0070] Ultrafiltration Experiment: Dead-end filtration experiments were conducted using an MSC300 ultrafiltration cup from Shanghai Sumo Co., Ltd., and a 30kDa ultrafiltration membrane from another company. 200 mL of a mixture of EPS and 50 mg / L TC was injected into the ultrafiltration cup, the valve was closed to seal the equipment, and high-purity nitrogen was used for pressurization, maintaining a pressure of 0.08 MPa. After filtration, the filtrate was collected and analyzed by liquid chromatography. (The EPS sample was extracted from sludge using a cation exchange resin extraction method. First, the sludge sample was centrifuged at 3000 rpm for 15 min, washed twice with 100 mM NaCl solution, and then resuspended in NaCl solution. Cation exchange resin was added at a concentration of 60 g / g sludge, and the mixture was continuously stirred at 200 rpm and 4℃ for 12 h, followed by centrifugation at 12000 rpm and 4℃ for 30 min. The supernatant was filtered through a 0.45 μm filter membrane to obtain the EPS solution sample.)

[0071] ③ The interaction between EPS and tetracycline was illustrated from the perspective of fluorescence signal analysis using three-dimensional fluorescence spectroscopy and Stern-Volmer fitting. A Hitachi F-7100 fluorescence spectrophotometer was used to obtain three-dimensional fluorescence spectra, with a deuterium lamp as the excitation source. The excitation and emission wavelength ranges were 200 nm to 450 nm and 250 nm to 550 nm, respectively, with a scan interval of 5 nm. Spectra were recorded at a scan rate of 7000 nm / min and a scan voltage of 700 V. The interaction between EPS and TC was studied using steady-state fluorescence quenching and Stern-Volmer fitting. EPS was extracted from sludge samples using the aforementioned cation exchange resin method. TC was used as a quencher to quench the fluorescence signal of EPS, with the TC concentration gradually increasing from 0 to 200 mg / L. The obtained fluorescence intensity was calculated using the Stern-Volmer equation: F0 / F = K. SV [Q]+1=k q τ0[Q]+1, where F0 and F are the fluorescence intensities in the presence and absence of the quencher TC, respectively, and K SV Let F0 be the Stern-Volmer fluorescence quenching constant, Kq be the fluorescence quenching rate constant, τ0 be the fluorescence lifetime, and Q be the molar concentration of the quencher. The binding constant and the number of binding sites can be calculated using the following modified Stern-Volmer equation (Equation 6-2): log(F0 / F-1) = logK A +nlog[Q], where K A is the binding constant, and n is the number of binding sites.

[0072] II. Experimental Analysis Methods:

[0073] I. Liquid Chromatography Analysis: Samples were pretreated using microwave digestion before liquid chromatography to break down the metal complexes of TC. The concentration of TC was determined using an Agilent 1260 high-performance liquid chromatograph (HPLC) equipped with a C18 column (2.1 × 50 mm inner diameter, 1.7 μm particle size). The mobile phase was a mixture of solvent A (acetonitrile) and solvent B (ultrapure water containing 0.1% chromatographic grade formic acid), with a flow rate of 0.6 mL / min and a gradient of 35% A and 65% B. The column temperature was controlled at 25 °C, and the sample injection volume was 20 μL.

[0074] II. Dissolved Organic Carbon Analysis: Total Organic Carbon (TOC) analyzers are instruments used to determine the total organic carbon content in water samples. They are widely used in environmental monitoring, water treatment, pharmaceuticals, food and beverage industries. TOC analyzers oxidize organic carbon in water samples to CO2 at high temperatures, and then use an infrared detector to measure the CO2 concentration. They have low detection limits and provide accurate results. This experiment used a German Jenamulti N / C3100 TOC analyzer to analyze the dissolved organic carbon (DOC) content of the collected solution samples to indicate the remaining amount of organic matter in the solution.

[0075] III. Determination of Al Content: Inductively Coupled Plasma Optical Spectrometry (ICP-OES) is commonly used to determine the content of metallic elements, especially in solutions. In ICP, a gas (usually argon) is heated and ionized to form a high-temperature plasma. The sample is injected into the plasma, where the elements are excited into excited states. These excited-state atoms or ions emit light of specific wavelengths, i.e., emission spectral lines. OES measures the intensity of these emission spectral lines and determines the concentration of different elements based on their characteristic spectral lines. This experiment uses the Thermo Fisher iCAPPro ICP-OES system, with argon as the plasma carrier gas, to analyze the residual Al in the solution after the reaction.

[0076] IV. Sludge Dewatering Performance Assessment: The capillary time to water absorption (CST) tester is an effective tool commonly used to assess the dewatering performance of excess sludge. The CST of the reacted excess sludge was measured using a Triton 304B tester and Whatman No. 17 chromatography filter paper. Each sample was tested in triplicate, and the average value was taken to assess changes in sludge dewatering performance.

[0077] V. Sludge Particle Size and Surface Potential Analysis: The Malvern laser particle size analyzer is an instrument used to measure particle size distribution. It employs laser scattering technology for particle size analysis and can measure particle sizes ranging from 0.1 μm to 2 mm. Its working principle involves irradiating the sample with a laser and measuring the intensity of scattered light from the particles at different angles. The particle size distribution is determined by analyzing the intensity distribution of the scattered light. This experiment used the Mastersizer 3000 laser particle size analyzer from Malvern (UK), with water as the dispersion medium and an opacity setting of 0-10%. The size of the generated flocs was analyzed, with each sample tested in triplicate and the average value taken. Zeta potential refers to a parameter indicating the surface charge state of suspended particles, which is important for understanding particle stability, interactions, and dispersibility. This experiment used the Zetasizer Nano ZSP from Malvern (UK) to analyze the Zeta potential of sludge flocs. The floc sample was injected into the sample chamber, ensuring the absence of air bubbles and impurities. The instrument measured the dynamic light scattering pattern of the particles under laser irradiation by emitting a laser beam. The Zeta potential was calculated based on the particle velocity and light scattering pattern. Measuring the zeta potential allows us to understand the surface charge state of particles and assess their dispersibility and stability.

[0078] VI. Analysis of conventional pollutants: COD was analyzed using the potassium dichromate digestion method, after digestion at 150℃ for 2 hours. Total phosphorus (TP) was analyzed using the ammonium molybdate spectrophotometric method, after digestion at 120℃ for 30 minutes.

[0079] VII. Quantum Chemical Calculations: DFT calculations were performed using Gaussian 16, with the Gaussian 09 integral grid used by default. Based on DFT, the geometric configurations of molecular fragments were optimized and frequencies were calculated using the B3LYP mixed-element exchange-correlated functional and the def2-SVP basis set under the SMD-water continuous solvation model. Single-point energy calculations were performed using the def2-TZVP basis set, and the Gibbs free energy at room temperature was corrected for each structure to obtain accurate thermodynamic reaction parameters. The Independent Gradient Model (IGM) in Multiwfn 3.7 was used to study the host-guest interactions within the complex molecules, and then colored isosurface plots were drawn using VMD 1.9.3. Techno-economic analysis (TEA) and environmental lifecycle cost (E-LCC) were used for environmental techno-economic evaluation. Hot water hydrolysis and ozone oxidation, as two-phase technologies currently used for the pretreatment of antibiotic production wastewater, were used as comparative references. The hot water hydrolysis treatment conditions were maintained at 85℃ for 3 hours per ton of water, while the ozone oxidation treatment conditions were an introduction of 1680g of ozone per ton of water. Both hot water hydrolysis and ozone oxidation reference processes treated 500.1±5.5mg / L, therefore Al... 3+ - Sludge pretreatment was also calculated using the same pollutant concentration conditions, namely, 5 kg of aluminum sulfate and 2808 g of industrial aluminum sulfate per ton of water. TEA focuses on capital and operating costs, while E-LCC mainly assesses its environmental impact through global warming potential (GWP).

[0080] III. Experimental Implementation and Analysis Results:

[0081] ①、Al 3+ It can enhance TC-sludge interface migration, Al 3+ Adding it can significantly improve the removal efficiency of tetracycline, and Al 3+ There exists an optimal dosage, meaning that the effect is best when the dosage satisfies the above formula (1):

[0082] Through the above-described three-dimensional fluorescence spectroscopy and Stern-Volmer fitting experiments, coordination-induced fluorescence traced the enhanced transfer of Al to the humic acid interface, proving that Al 3+ It is reasonable to mediate the binding of TC to the sludge EPS interface; specifically, such as... Figure 1 As shown in -a, batch experiments were conducted in a 400 mL reaction system, with a TC contamination concentration set at 10 mg / L and a sludge concentration of 2 g / L. It was observed that without the addition of Al... 3+Under these conditions, only 1.92 mg / L of TC remained in the water, meaning that 2 g / L of sludge could achieve an 80.8% removal efficiency for 10 mg / L of TC. With the increase of Al... 3+ With the gradual addition of [amount], the removal rate of TC gradually increased, reaching [amount] at 10 mg / L Al. 3+ The removal efficiency reaches its maximum at the optimal dosage, at 96.5%. Optimal Al concentrations exceeding 10 mg / L... 3+ After dosage, the removal rate showed a slow downward trend, i.e., Al 3+ There is an optimal dosage. Further, a higher concentration of 5 g / L sludge was used to address a TC contamination level of 10 mg / L. Figure 1 a) Without adding Al 3+ Under these conditions, due to the increased sludge concentration, the removal efficiency of TC increased to 87.8%. With the addition of Al... 3+ The optimal removal efficiency for TC was further improved to 94.9%, but there was no further advantage compared to the 2 g / L sludge concentration. Furthermore, due to the increased sludge concentration, the required Al input at the optimal point... 3+ Increasing the dosage to 20 mg / L will result in more residual sludge after treatment.

[0083] ② When the intensity of tetracycline pollution changes, the method described in the examples shows better removal efficiency for tetracycline. The best effect is achieved when the amount of trivalent metal ions and sludge added meets the formula in the examples.

[0084] Increase the TC pollution intensity to 50 mg / L, such as... Figure 1 As shown in b, at this point, the sludge concentration of 2 g / L is achieved without the addition of Al. 3+ Under these conditions, the removal efficiency of TC was only 48.8%; with Al 3+ As the dosage gradually increases, the TC removal rate gradually increases, especially at an Al concentration of 10 mg / L. 3+ The maximum removal rate was achieved at the specified dosage of 95.4%; with Al 3+ When the dosage exceeds the optimal point, the removal rate gradually decreases. Increasing the sludge concentration to 5 g / L... Figure 1 b) Observation was made without the addition of Al 3+ Under these conditions, the removal efficiency of TC was significantly improved to 81.5%; further addition of Al 3+ The removal rate of TC was further improved at 15 mg / L Al. 3+ At the dosage, the removal rate reached a maximum of 98.5%; Al 3+When the dosage was further increased beyond the optimal level to 60 mg / L, the removal rate decreased slightly but remained at a high level of >96%. For a TC pollution intensity of 50 mg / L, further increasing the sludge concentration to 10 g / L did not show any further necessity. Without the addition of Al... 3+ Under these conditions, the removal efficiency of TC only slightly increased to 87.7% compared to a sludge concentration of 5 g / L; the addition of Al 3+ This led to a further increase in TC removal rate at 15 mg / L Al. 3+ The removal rate reached its maximum of 96.7% at the appropriate dosage; further improving Al 3+ The dosage caused a slight decrease in TC removal rate. Overall, for a TC pollution intensity of 50 mg / L, a 2 g / L sludge concentration is insufficient; a 5 g / L sludge concentration showed the highest and most stable removal efficiency; and a 10 g / L sludge concentration did not demonstrate better pollutant removal performance. Therefore, an appropriate sludge concentration should be selected, and blindly using higher concentrations is unnecessary.

[0085] When the TC concentration reaches 200 mg / L, it is close to the pollution intensity of antibiotic production wastewater in the pharmaceutical industry. For example... Figure 1 As shown in -c, at this concentration level, a sludge concentration of 2 g / L without the addition of Al 3+ Under these conditions, the removal efficiency of TC was only 28.8%; and the addition of Al... 3+ Although the removal rate of TC increased afterward, it remained within the optimal range of 10 mg / L Al. 3+ At the given dosage, the maximum removal rate of TC was only 54.7%; accompanied by Al 3+ Excessive addition of TC gradually reduced the removal rate. At this point, a sludge concentration of 2 g / L was insufficient to efficiently remove a high concentration of 200 mg / L TC. Increasing the sludge concentration to 5 g / L, without adding Al... 3+ Under these conditions, the removal efficiency of TC was further improved to 57.3%, and Al 3+ Further addition of TC continuously improves the removal rate, with an optimal Al concentration of 15 mg / L. 3+ At the given dosage, the TC removal rate reached its maximum of 91.2%; thereafter, excessive Al was added. 3+ This led to a significant decrease in TC removal rate, with Al at 60 mg / L. 3+ At the initial dosage, the TC removal rate had decreased to 60.3%. Further increasing the sludge concentration to 10 g / L significantly improved the sludge removal efficiency for 200 mg / L TC to 71.4%. Adding Al... 3+ This further promoted the removal of TC from the water, at an optimal Al concentration of 20 mg / L. 3+ At the dosage level, 96.5% of TC was removed; similarly, with Al3+ With further excessive increases in dosage, the removal rate of TC gradually decreased, and at 60 mg / L Al... 3+ The TC removal rate decreased to 82.7% at the given dosage.

[0086] Al was observed under all three TC loads mentioned above. 3+ When the dosage exceeds the optimal value, the removal efficiency of TC gradually decreases. This may be because excessive dosage leads to residual Al in the water. 3+ The binding of TC to the solid-phase interface is achieved through binary coordination. This water-solid two-phase competitive coordination process can also occur at the sludge interface. Therefore, the residual Al in the post-reaction solution was analyzed by ICP-OES, and the results are as follows: Figure 1 The df is shown. In the optimal Al 3+ At the dosage, Al 3+ Al is fully utilized at the sludge interface, and no residual Al is generated in the aqueous phase. 3+ When the dosage exceeds the optimal TC removal dose, the residual Al content in the solution increases with Al concentration. 3 + The dosage increased and continued to rise. The existence of these excess Al explains Al. 3+ The reason why there is an optimal dosage is that when Al... 3+ When the dosage exceeds the optimal level, the Al in the solution... 3+ It is possible that the TCs already bound at the sludge floc interface will be released back into the water through coordination with the TCs.

[0087] In summary, Al 3+ Enhanced sludge floc interface achieved high removal efficiency for TC under different loads. Al 3 + - The universality of sludge interface complexation mechanisms; Due to the high similarity in molecular structure among tetracycline family antibiotics, including tetracycline, chlortetracycline, oxytetracycline, doxycycline, minocycline, and tigecycline, many antibiotics share the same key structural feature: a six-membered ring composed of enol oxygen and carboxyl oxygen, serving as a chelation site ( Figure 2 This unique structural property indicates that by utilizing Al 3+ The mediated interface immobilization strategy may be effective not only against a specific tetracycline antibiotic but also against the entire tetracycline family. Experimental results further validated this hypothesis: under optimized treatment conditions, namely 10 g / L sludge and 20 mg / L Al... 3+ When used in combination, the removal rate of various tetracycline antibiotics exceeded 93% when the concentration was 200 mg / L. Figure 2 These data indicate that Al 3+Coordination-modified sludge interfaces can broadly and efficiently remove different types of tetracycline antibiotic pollution from water bodies. This not only demonstrates the universality and efficiency of this strategy in antibiotic wastewater treatment, but also provides strong support for the practical treatment of tetracycline-polluted water bodies.

[0088] ③ Further characterize the effectiveness and stability of the method of the present invention by analyzing the properties of the sludge;

[0089] Stability of pollutant solidification: After TC (total sulfide) is incorporated, the sludge undergoes free settling, which carries pollutants away from the aqueous phase, thus transferring them from the continuous aqueous medium to the discontinuous solid sludge medium, achieving pollutant control. After completing the pretreatment stage, the sludge is treated as excess sludge and proceeds to the next stage for dewatering. However, during this process, close attention must be paid to the potential re-release of TC trapped in the sludge under intense mechanical dewatering, as this may affect the overall effectiveness of the pretreatment process. 5 g / L sludge and 5 g / L sludge + 15 mg / L Al were used respectively. 3+ To remove 200 mg / LTC, the resulting mixture was subjected to solid-liquid separation in a laboratory high-speed centrifuge, simulating the action of sludge in a centrifugal dewatering process. The results showed that during the high-speed centrifugal dewatering of sludge, the individual sludge interface and Al... 3+ - The total TC captured at the sludge interface was not released back into the liquid phase after centrifugation and dewatering, demonstrating high pollutant solidification stability. Figure 3 Furthermore, the removal rate of TC increased slightly, from 58.8% and 94.8% to 63.6% and 95.2%, respectively. This is likely due to the centrifugation process causing more thorough separation of the tiny suspended flocs in the water, allowing TC to further transfer into the solid phase. These results demonstrate that Al... 3+ - The sludge interface can stabilize and solidify TC pollutants, preventing their re-release into the water during subsequent sludge dewatering processes. Conversely, the sludge dewatering process synergizes with the antibiotic pretreatment process, effectively solving the problem of solid-liquid separation and collection of pollutants captured by the sludge.

[0090] The impact of Al on sludge dewatering: 3+ It has a coagulation and conditioning effect on sludge, and is often used for chemical preconditioning of excess sludge before dewatering to improve sludge floc characteristics and enhance sludge dewatering performance. Capillary absorption time (CST) is a substitute indicator for evaluating sludge dewatering performance. Using 5 g / L sludge at different Al... 3+ At a dosage of 200 mg / LTC, the pretreated mixture was allowed to settle, and 80% of the supernatant was skimmed off to obtain the remaining sludge. The CST value was then used to determine the dewatering performance of the pretreated sludge. Figure 4 As shown, in the absence of Al 3+With the addition of [agent], the CST value of the remaining sludge was 1.30 s·L / g. As Al [increased / conducted]... 3+ With the addition of [a specific ingredient], the CST value of the sludge decreased significantly, with an Al concentration of 60 mg / L. 3+ At the given dosage, the CST value decreased to 0.74 s·L / g, indicating improved sludge dewatering properties. Analysis of the Zeta potential and floc size further revealed the coagulation and conditioning effect of Al3+ on the sludge flocs. The initial surface potential of the sludge flocs was -176.3 mV, and increased with increasing Al3+ content. 3+ The amount of Al gradually increased with the addition of Al. 3+ When the dosage reached 20 mg / L, the surface potential increased to -21.0 mV, reflecting the effect of Al. 3+ Significant charge neutralization effect on sludge flocs ( Figure 5 a). Charge neutralization leads to decreased stability of the sludge system, reducing the repulsive force and compressibility between flocs during sludge dewatering, thereby improving sludge dewatering performance. Further instability and aggregation of the flocs cause the sludge floc size to continuously increase. Figure 5 b). Increased floc size is generally positively correlated with improved sludge dewatering properties; larger flocs mean more bound water is released. (via Al) 3+ The coagulation effect modulates the properties of sludge flocs, effectively improving the dewatering performance of the sludge. Furthermore, Al... 3+ The coagulation effect on sludge flocs also improves the settling performance of the sludge, thus achieving more efficient separation and concentration of excess sludge after the pretreatment stage. In this process, Al... 3+ This significantly enhances the sludge interface's ability to immobilize total chloride (TC) while simultaneously pre-conditioning the sludge for dewatering, playing a dual role in the treatment process. From a holistic system perspective, this pretreatment strategy places the traditional chemical pre-conditioning step before sludge dewatering before biological wastewater treatment, allowing it to additionally undertake the task of pre-treating high-concentration antibiotic wastewater. In this process design, the excess sludge becomes a misplaced resource, achieving resource repositioning and optimized utilization. Currently, sludge dewatered from wastewater treatment plants requires further treatment and disposal and cannot be directly released into the environment. This further mitigates the risk of antibiotic-pretreated sludge re-entering the ecosystem. Furthermore, tetracyclic antibiotics are easily thermally degraded, decomposing at relatively low temperatures such as 85°C. Among the current abundant sludge disposal technology options, thermal drying (160-220°C), hot hydrolysis (165°C) anaerobic digestion, and more vigorous sludge incineration (900-1300°C) are particularly suitable for the subsequent disposal of this antibiotic-pretreated sludge. This integrated wastewater-sludge process effectively ensures the safety of wastewater and sludge treatment.

[0091] Treatment efficacy of antibiotics under complex water conditions: The above experimental results verify that Al… 3+ Highly efficient TC removal is achieved by enhancing the sludge-flocculation interface through coordination. This pollutant removal performance shows great potential for development into a novel pretreatment technology for antibiotic wastewater. However, considering the more complex water quality conditions of real antibiotic wastewater, especially antibiotic production wastewater, which contains not only characteristic pollutants like antibiotics but also large amounts of conventional pollutants such as COD and TP, further investigation into the effectiveness of this interface removal process under complex water quality conditions is necessary. Figure 6 As shown, synthetic wastewater with a TC load of 200 mg / L and a COD load of 4507 mg / L was prepared to simulate complex antibiotic production wastewater. Under the condition of a sludge concentration of 5 g / L, the initial removal rate of TC by the sludge was 41.4%; with Al 3+ With increasing dosage, TC removal efficiency gradually improves, when Al 3+ The removal rate reached its highest value of 87.9% when the dosage reached 80 mg / L. Figure 6 a) When the sludge concentration increased to 10 g / L, the initial removal rate of TC rose to 62.3%, and in Al 3+ The removal rate reached its optimal performance of 91.6% when the dosage was 100 mg / L. Figure 6 (b) The removal rate of TC showed a decreasing trend after exceeding the optimal dosage. The high efficiency of TC removal under complex wastewater conditions indicates that this pretreatment strategy has high selectivity for the characteristic pollutant TC and can undertake the task of pretreatment of antibiotic wastewater.

[0092] Meanwhile, it was observed that, compared to the optimal Al concentration of 20 mg / L under simple water quality conditions, 3+ Dosage (with a water quality heterogeneity coefficient α value of 0.74) was used to simulate the optimal TC removal conditions for Al under complex water quality. 3+ When the dosage was increased to 80 mg / L, the water heterogeneity coefficient α changed to 0.185, indicating that other complex components in the wastewater (such as COD and TP) affected Al. 3+ The competitive effect. This additional Al... 3+ It plays an important role in the simultaneous removal of traditional pollutants (such as COD and TP). Under optimal conditions, namely 5 g / L sludge and 80 mg / L Al... 3+ At that time, COD and TP decreased by 35.0% and 49.7%, respectively; while at 10 g / L sludge and 100 mg / L Al 3+ Under optimal conditions, the removal rates of COD and TP reached 31.3% and 61.9%, respectively. Figure 6 c, Figure 6 d). Pretreatment of NH4 +The removal of [specific pollutants] was not significantly affected. These results indicate that the Al3+-sludge interfacial complexation pretreatment strategy not only effectively removed the characteristic pollutant antibiotics but also significantly reduced the load of traditional pollutants. This will greatly alleviate the pollutant burden on subsequent biological wastewater treatment stages, enabling biological wastewater treatment to operate under lower load and lower carbon conditions, which is conducive to promoting the sustainability of wastewater systems.

[0093] Hot water hydrolysis and ozone oxidation are currently two main technologies for the pretreatment of wastewater containing high concentrations of tetracyclic antibiotics. Using these two pretreatment technologies as a reference, further analysis was conducted on their interaction with Al2O3 and E-LCC. 3+ - A comparative analysis of the techno-economic and environmental life-cycle costs of sludge pretreatment was conducted. The results showed that, per ton of antibiotic wastewater, thermal hydrolysis had the highest economic cost, reaching 77.52 CNY / ton, mainly due to the high specific heat capacity of water leading to higher heating energy consumption. In contrast, ozone oxidation further reduced the economic cost to 25.2 CNY / ton. Al... 3+ - The cost per ton of water treated by sludge pretreatment is only 3.17 CNY. This is because it recycles sludge, a byproduct of wastewater treatment plants, significantly reducing material input in the pretreatment process, requiring only a small amount of additional aluminum salts. It requires an average of only 0.455 mg of Al3+ to treat 1 mg of TC. Examining the environmental lifecycle costs of the three pretreatment technologies from a carbon emission perspective, the results show that thermal hydrolysis emits 0.0443 kg CO2 / ton, while ozone oxidation emits 4.4 times more, reaching 0.1931 kg CO2 / ton. This is because ozone cannot be fully utilized during pretreatment, with most escaping into the atmosphere. Ozone emitted into the troposphere is itself a greenhouse gas, thus generating high carbon emissions. In contrast, due to lower material and energy inputs and the non-degradable pollutant removal pathway, Al3+... 3+ - Sludge pretreatment also resulted in the lowest carbon emissions, at only 0.0009 kg CO2 / ton. These results indicate that Al 3+ - Sludge pretreatment, compared with the two more mature pretreatment technologies of hot water hydrolysis and ozone oxidation, shows advantages in terms of economic cost and environmental life cycle cost, and has the potential for further research and development.

[0094] In summary, such as Figure 7 Al 3+ - The sludge interface complexation pretreatment strategy has achieved multiple benefits in the context of wastewater-sludge systems. 3+- Sludge exhibits exceptional efficiency in pretreating characteristic pollutants in antibiotic wastewater, achieving selective and efficient removal of TC at concentrations up to 200 mg / L, with a removal rate exceeding 90%, even under complex water conditions. Secondly, the pretreatment process not only targets TC but also significantly reduces the load on traditional pollutants such as COD and TP. This dual effect greatly reduces the operating costs of subsequent wastewater treatment and is expected to further reduce the carbon footprint under low-load operation. Thirdly, pretreatment also synergistically improves sludge dewatering properties, which to some extent replaces the original chemical conditioning steps before excess sludge dewatering, further reducing the consumption of sludge conditioning agents. Essentially, Al 3+ The interfacial complexation further enhances the abiotic functions of the sludge interface, enabling it to effectively address the multiple challenges of antibiotic wastewater without requiring excessive additional investment outside of existing wastewater-sludge systems, thus maximizing economic and environmental benefits. The resource properties of the excess sludge are further developed, allowing it to undergo an additional antibiotic pretreatment process before exiting the wastewater treatment system.

[0095] The method of this invention is not only effective against tetracyclines, but also against other types of pollutants with ligand characteristics in the aquatic environment, such as fluoroquinolone antibiotics, for this interfacial complexation mechanism. This further coordinates the reduction of pollution and carbon emissions and the improvement of efficiency in the wastewater-sludge system, thereby optimizing the synergistic pursuit of sustainability and process efficiency.

[0096] This invention's embodiments study the use of trivalent metal Al 3+ Coordination-mediated, and through the solid-phase interface provided by sludge flocs, constructing Al 3+ This study evaluated the efficacy of sludge interfacial contact complexation pretreatment technology for treating high-concentration antibiotic production wastewater. It explored the enhanced mechanism of metal coordination in capturing pollutants at the biofloc interface and synergistically achieved the removal of conventional pollutants and simultaneous improvement of sludge dewatering properties. The results deepened the understanding of the dynamics of the water-solid interface in sludge and promoted the further application of the non-biological functions of sludge in wastewater treatment. Further application methods include... Figure 8 As shown.

[0097] Example 2: The difference between this example and Example 1 is that the trivalent metal used in this example is aluminum sulfate.

[0098] Example 3: The difference between this example and Example 1 is that the trivalent metal used in this example is aluminum nitrate.

[0099] Example 4: The difference between this example and Example 1 is that the trivalent metal used in this example is ferric chloride.

[0100] Example 5: The difference between this example and Example 1 is that sludge and trivalent metal ion mediators are first added to the tetracycline wastewater, and the mixture is stirred at 200 rpm / min for 35 seconds. Then, it is stirred slowly at 40 rpm / min for 5 minutes, and then allowed to settle for 120 minutes to separate the solid and liquid phases, thus completing the treatment.

[0101] Example 6: The difference between this example and Example 1 is that sludge and trivalent metal ion mediators are first added to the tetracycline wastewater, and the mixture is stirred at 400 rpm / min for 25 seconds. Then, it is stirred slowly at 40 rpm / min for 4 minutes, and then allowed to settle for 30 minutes to separate the solid and liquid phases, thus completing the treatment.

[0102] Example 7: The difference between this example and Example 1 is that in this example, a is 0.1 and the sludge ratio coefficient b is 0.01.

[0103] Example 8: The difference between this example and Example 1 is that in this example, a is 2 and the sludge ratio coefficient b is 1.4.

Claims

1. A method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation, characterized in that, Includes the following steps: S1. Take trivalent metal ion dielectric, sludge and tetracycline wastewater according to the proportion; wherein, the trivalent metal ion dielectric is a trivalent metal salt, and the amount of trivalent metal ion dielectric added satisfies formula (1): （1）； In the formula, x The dosage of trivalent metal ion dielectric is expressed in grams (g), and C is the concentration of tetracycline in the tetracycline wastewater, expressed in g / m³. 3 V represents the volume of tetracycline wastewater, in cubic meters (m³). 3 , a The wastewater heterogeneity coefficient; The amount of sludge added satisfies formula (2): （2）； In the formula, y The amount of sludge added is based on dry weight, in grams. b This is the sludge mixing ratio coefficient. x The dosage of trivalent metal ion dielectric is expressed as the mass of the metal element. The trivalent metal ion is Al 3+ or Fe 3+ ; The sludge ratio coefficient b The methods for determining this include: First, take 200-400 mL of tetracycline wastewater with a concentration of C; add the following amount: x The trivalent metal ion dielectric is used to obtain a premix; according to the sludge proportioning coefficient b Within a range of 0.01 to 1.4, multiple parallel experiments were conducted, and sludge was added to the premix. Then, operation S2 was performed to obtain treated tetracycline wastewater. The sludge ratio coefficient corresponding to the parallel experiment with the highest tetracycline removal rate in the treated tetracycline wastewater was selected. b ; S2. Mix the trivalent metal ion dielectric, sludge and tetracycline wastewater, stir and let it stand for 30~120 minutes to settle, and the treatment is complete.

2. The method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation as described in claim 1, characterized in that, The x The calculation method is as follows: x = m × w% ; m For the mass of trivalent metal salts, w% This represents the mass fraction of the metal element in a trivalent metal salt.

3. The method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation as described in claim 2, characterized in that, The trivalent metal ion is Al 3+ When the trivalent metal ion dielectric is any one of aluminum chloride, aluminum sulfate, and aluminum nitrate.

4. The method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation as described in claim 1, characterized in that, The wastewater heterogeneity coefficient a The value range is 0.1 to 2.

5. The method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation as described in claim 1, characterized in that, The sludge is pretreated sludge from a water treatment plant. The pretreatment method is as follows: first, take the sludge from the water treatment plant and put it into water with a volume of 2 to 3 times that of the sludge. Let it stand and settle for 24 hours at a temperature of 4°C. Then, skim off the supernatant to obtain the sludge. The sludge is stored at a temperature of 4°C.

6. The method for treating tetracycline wastewater based on metal ion-mediated sludge floc complexation as described in claim 1, characterized in that, The stirring treatment described in S2 includes: first, adding sludge and trivalent metal ion dielectric to tetracycline wastewater, stirring at a speed of 200-400 rpm / min for 25-35 seconds, then continuing to stir slowly at a speed of 40 rpm / min for 4-5 minutes, and then allowing it to settle for 30-120 minutes to separate the solid and liquid phases, thus completing the treatment.

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