Polyaluminum chloride and polyferric sulfate composite sewage treatment agent and preparation method thereof

Abstract

The application discloses a composite sewage treatment agent containing polyaluminum chloride and polyferric sulfate and a preparation method thereof. The composite sewage treatment agent is prepared from the following raw materials in parts by weight: 15-25 parts of polyaluminum chloride, 10-20 parts of polyferric sulfate, 10-18 parts of a composite microbial flora, 5-12 parts of an adsorption enhancer, 0.5-1.5 parts of rhamnolipid, and 2-5 parts of poly-gamma-glutamic acid. The composite sewage treatment agent can realize rapid and efficient sewage treatment and can meet certain long-acting treatment requirements.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment agent preparation technology, specifically relating to a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate and its preparation method. Background Technology

[0002] With the acceleration of industrialization and urbanization, the composition of modern wastewater is becoming increasingly complex, often exhibiting characteristics of "compound pollution" such as high concentrations of organic matter (COD / BOD), high ammonia nitrogen and total nitrogen, rich in heavy metal ions, and accompanied by recalcitrant emulsified oils. Traditional wastewater treatment typically employs a two-stage independent treatment process of "physicochemical coagulation and sedimentation" and "biodegradation".

[0003] In the physicochemical stage, commonly used inorganic polymeric flocculants (such as polyaluminum chloride PAC and polyferric sulfate PFS) have good removal effects on suspended solids (SS) and colloidal phosphorus, but their removal rates for dissolved organic matter and ammonia nitrogen are extremely low. In the biochemical stage, although microorganisms (such as nitrifying bacteria and denitrifying bacteria) can effectively remove nitrogen and carbon, traditional free-state or simply biofilm-forming microbial communities have extremely poor stress resistance. Specifically, this manifests in two ways: firstly, trace amounts of heavy metal ions (such as Cu) in wastewater... 2+ Pb 2+ Cr 6+ First, it can easily inactivate the microbial enzyme system, leading to the collapse of the biochemical system. Second, nitrifying bacteria consume a large amount of alkalinity and produce acid during the process of converting ammonia nitrogen into nitrate nitrogen, causing a sudden drop in the local microenvironment pH, which in turn inhibits the continued progress of the nitrification reaction. Third, the traditional microbial denitrification process (especially the denitrification stage) has low electron transfer efficiency, resulting in a slow total nitrogen removal rate.

[0004] In recent years, the preparation of "integrated wastewater treatment agents" by combining inorganic flocculants, adsorbents, and microbial communities has become a research hotspot. However, existing composite agents have significant drawbacks: First, simple physical mixing can lead to the chemical agents being toxic to microorganisms; second, traditional modified adsorbent materials (such as ordinary activated carbon or silane-modified minerals) suffer from problems such as easy pore clogging, lack of pH buffering capacity, and incomplete heavy metal removal; finally, traditional chemical surfactants (such as CAB) added to solve the problem of organic matter encapsulation are not only difficult to degrade, producing large amounts of persistent foam, but also cause serious secondary pollution.

[0005] In the prior art, such as patent document CN120647099A, a method for preparing a polyaluminum chloride-based composite wastewater treatment agent is provided. By weight, it is prepared from the following raw materials: 20-35 parts polyaluminum chloride, 5-12 parts slow-release microorganisms, 3-6 parts modified activated carbon, 4-8 parts modified attapulgite, 0.5-1.2 parts cocamidopropyl betaine, and 2-5 parts polyacrylamide. Using polyaluminum chloride as the main raw material, and by combining modified activated carbon, modified attapulgite, and slow-release microorganisms, the prepared water treatment agent has a good effect on removing nitrogen, phosphorus, and heavy metals, and has a good slow-release effect. However, the above-mentioned technical solutions, which use microcapsules to prepare slow-release microorganisms, have shortcomings such as time lag in drug dissolution and release, and the high concentration of metal ions still causing microenvironmental collapse after the capsule ruptures, resulting in low bacterial survival rates. At the same time, the cocamidopropyl betaine used in these solutions easily generates a large amount of foam that is difficult to eliminate in water treatment, and also increases the COD of the water, which has a potential inhibitory effect on the subsequent biofilm formation and survival of microorganisms. Polyacrylamide is a synthetic polymer that is extremely difficult to degrade naturally.

[0006] Therefore, the present invention aims to further optimize the formulation and provide a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate, and its preparation method. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate and its preparation method, which can achieve rapid and efficient wastewater treatment and meet certain long-term treatment requirements.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate, which is prepared by weight from the following raw materials: 15-25 parts polyaluminum chloride, 10-20 parts polyferric sulfate, 10-18 parts composite microbial flora, 5-12 parts adsorption enhancer, 0.5-1.5 parts rhamnolipid, and 2-5 parts poly-γ-glutamic acid.

[0010] As a preferred embodiment of the technical solution of the present invention, the preparation of the composite microbial community includes the following steps:

[0011] S11. Polylactic acid is dissolved in dichloromethane to form an organic phase; then modified zeolite is added to the organic phase and ultrasonically dispersed to obtain a mixture; next, an aqueous solution containing polyvinyl alcohol is added dropwise to the mixture, stirred and heated until the dichloromethane is completely evaporated, and finally washed and dried to obtain the carrier.

[0012] S12. Add the carrier obtained in step S11 to the dopamine solution, stir and react under light-protected conditions, and then wash and dry to obtain the modified carrier.

[0013] S13. Add the modified carrier obtained in step S12 to the mixed bacterial suspension, then shake and incubate, and finally filter and freeze dry to obtain the composite microbial community.

[0014] As a preferred embodiment of the technical solution of the present invention, in step S11, the ratio of polylactic acid, dichloromethane, and modified zeolite is 2~8g:40~60mL:5~15g; the concentration of the aqueous solution containing polyvinyl alcohol is 0.5~1.5wt%; and the volume ratio of the mixed solution to the aqueous solution containing polyvinyl alcohol is 1:5~10.

[0015] The preparation of the modified zeolite powder includes the following steps: adding zeolite powder to a 1-2 mol / L hydrochloric acid solution, stirring at 50-65°C, followed by washing and drying to obtain pre-modified zeolite; then adding the pre-modified zeolite to a 75-90 wt% ethanol solution, adjusting the pH of the system to 4.0-5.0 with acetic acid, adding 3-5% KH550 by weight of the pre-modified zeolite, stirring at room temperature, then heating to 65-75°C, and stirring again for 4-8 hours; after treatment, centrifuging, washing, and drying to obtain modified zeolite.

[0016] As a preferred embodiment of the technical solution of the present invention, in step S12, the preparation of dopamine solution includes the following steps: adding dopamine hydrochloride to Tris-HCl buffer solution with a pH of 8.2~8.7, and controlling the concentration at 0.5~4 mg / mL;

[0017] The ratio of carrier to dopamine solution is 1g: 5~10mL;

[0018] The stirring reaction was carried out at room temperature for 8 to 24 hours.

[0019] As a preferred embodiment of the technical solution of the present invention, in step S13, the total viable count of the mixed bacterial suspension is not less than 1×10⁻⁶. 10 CFU / g; The mixed bacteria were obtained by mixing Nitrifying Bacillus, Pseudomonas mendoza and Bacillus subtilis in a live count ratio of 1:1:1;

[0020] The shaking incubation temperature is 25~35℃, and the incubation time is 12~36h.

[0021] As a preferred embodiment of the present invention, the preparation of the adsorption enhancer includes the following steps:

[0022] S21. Preparation of nitrogen-doped biochar;

[0023] S22. Add the nitrogen-doped biochar obtained in step S21 to deionized water and disperse it by ultrasonication to obtain a suspension.

[0024] S23. Add the metal salt solution to the suspension obtained in step S22 and stir at room temperature for 0.5 to 4 hours to obtain a mixed solution.

[0025] S24. Under heating conditions, sodium phytate intercalation solution is slowly added dropwise to the mixture obtained in step S23. During the dropwise addition, the pH value of the system is adjusted by sodium hydroxide solution. After the dropwise addition is completed, the reaction is continued to be carried out at a constant temperature with stirring. After the reaction is completed, the mixture is transferred to a reactor for hydrothermal reaction. After the reaction is completed, the mixture is cooled, centrifuged, washed, and dried to obtain the adsorption enhancer.

[0026] As a preferred embodiment of the technical solution of the present invention, in step S21, the preparation of nitrogen-doped biochar includes the following steps: drying and crushing straw, sieving it through an 80-150 mesh screen, adding it to deionized water, then adding urea and potassium bicarbonate, heating and stirring, and drying to obtain a precursor; wherein, the mass ratio of straw, urea, and potassium bicarbonate is 1:0.8-1.2:0.4-0.6;

[0027] The precursor was pyrolyzed at 730-765℃ for 1-4 hours under nitrogen protection. After pyrolysis, it was cooled and then soaked in 0.5-1.5 mol / L hydrochloric acid solution. Finally, it was washed with deionized water and dried to obtain nitrogen-doped biochar.

[0028] As a preferred embodiment of the technical solution of the present invention, in step S22, the concentration of the suspension is 10~30 g / L;

[0029] In step S23, the preparation of the metal salt solution includes the following steps: weigh magnesium nitrate hexahydrate and aluminum nitrate nonahydrate at a molar ratio of 2:1, add them to deionized water, and stir until homogeneous; the concentration of magnesium nitrate hexahydrate is 0.5~1 mol / L.

[0030] The volume ratio of the metal salt solution to the suspension is 2:0.8~1.5.

[0031] As a preferred embodiment of the technical solution of the present invention, in step S24, the preparation of the sodium phytate intercalation solution includes the following steps: preparing a phytic acid aqueous solution with a concentration of 40~60wt%, and then adjusting the pH to 9.0~9.5 with a sodium hydroxide solution of 1.6~2.5mol / L.

[0032] The heating temperature is 55~70℃; the pH value of the system is controlled at 9.5~10.0; the constant temperature stirring reaction time is 1~4h; the hydrothermal reaction temperature is 110~130℃, and the reaction time is 6~24h.

[0033] Secondly, the present invention also provides a method for preparing the above-mentioned composite wastewater treatment agent, comprising the following steps: premixing polyaluminum chloride and polyferric sulfate, adding rhamnolipid, stirring at 35~45°C, then adding adsorption enhancer and poly-γ-glutamic acid, and stirring again; cooling to room temperature, dry mixing in composite microbial flora, stirring evenly, and then the agent is ready.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This invention provides a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate. With polyaluminum chloride and polyferric sulfate as the main components, it achieves rapid and efficient wastewater treatment by introducing a composite microbial community, an adsorption enhancer, rhamnose glycolipids, and poly-γ-glutamic acid.

[0036] This invention provides a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate. The rhamnolipid used has the advantages of being biodegradable and non-toxic, and can significantly promote the secretion of extracellular polymers (EPS) by mixed bacterial communities. This accelerates the adhesion of microorganisms to the carrier surface and the formation of biofilm from a physiological perspective, thereby improving the treatment effect. The poly-γ-glutamic acid used not only has extremely strong flocculation and sedimentation capabilities, but is also completely non-toxic and biodegradable.

[0037] This invention provides a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate. The composite microbial community is mainly based on an organic-inorganic composite carrier. Through modification with polydopamine, direct and firm adsorption of the microbial community is achieved, overcoming the shortcomings of the traditional microbial community encapsulation method. Specifically, the composite carrier uses polylactic acid as the organic carrier and zeolite as the inorganic carrier. The use of polylactic acid takes into account the carbon source requirements of bacteria such as Pseudomonas mendoza during denitrification. Zeolite itself has a very good ammonia nitrogen adsorption capacity, which can enrich ammonia nitrogen in wastewater onto the carrier surface, providing a high concentration of nitrogen source for nitrifying bacteria and greatly improving the nitrification rate. In the preparation process, the inventors modified the zeolite. First, it was subjected to pore-expanding activation treatment by acid washing to expose the silanol groups on the surface. Then, it was modified with KH550 to achieve amylation modification of the zeolite surface. The above modification is beneficial to its composite with polylactic acid, and the introduction of amino groups is beneficial to improving the encapsulation modification of dopamine, thus improving the modification effect and ultimately achieving the effect of improving the adhesion of microbial communities. Meanwhile, the inventors also modified the composite carrier with dopamine. The purpose of this modification is to enable the microbial community to attach efficiently through the abundant active groups on the surface of dopamine. This direct adsorption method reduces mass transfer resistance, allowing microorganisms to directly contact the wastewater and further improve treatment efficiency.

[0038] This invention provides a composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate. The adsorption enhancer is mainly composed of biochar and magnesium aluminum hydrotalcite (MgA) structures. The adsorption enhancer is prepared by growing MgA on nitrogen-doped biochar, overcoming the disadvantage of easy aggregation when using MgA alone. Specifically, the biochar is modified by nitrogen doping, and further improved by growing MgA, thus increasing the specific surface area of ​​the material. This is beneficial for subsequent phytic acid modification. Phytic acid modification facilitates the intercalation of MgA and introduces a large number of active binding sites (such as hydroxyl groups), improving compatibility with the composite microbial community and further enhancing the treatment effect. Furthermore, the choice of nitrogen-doped biochar in this invention also considers the sensitivity of the microbial community to the pH of the system. For example, during denitrification by *Pseudomonas mendoza*, nitrogen-doped biochar can transfer electrons, while the surface MgA structure can consume protons (H+). + It acts as a pH buffer, balancing the acidity of the system and preventing excessive pH fluctuations. Of course, biochar and magnesium aluminum hydrotalcite structures are themselves excellent adsorbent materials, capable of providing a certain degree of wastewater treatment.

[0039] In summary, by optimizing the types of substances and carrying out targeted modifications, the composite wastewater treatment agent prepared by this invention can achieve very good treatment results. Detailed Implementation

[0040] The embodiments of the present invention are described in detail below. All embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0041] In this embodiment of the invention, polyaluminum chloride was purchased from Shenzhen Qingyuan Water Purification Equipment Co., Ltd.

[0042] Polyferric sulfate was purchased from Jinan Guocheng Chemical Co., Ltd.

[0043] The nitrifying bacteria was Nitrifying Bacillus vesiculosus, purchased from Beijing BioBio Biotechnology Co., Ltd.

[0044] Mendoza Pseudomonas was purchased from Beijing BioBio Biotechnology Co., Ltd.

[0045] Bacillus subtilis was purchased from Beijing Bio-Bio Biotechnology Co., Ltd.

[0046] Polylactic acid was purchased from Zhejiang Hisun Biomaterials Co., Ltd., brand name Revode 110;

[0047] Polyvinyl alcohol was purchased from Sichuan Weihua Chemical Co., Ltd., and its brand name was PVA-1788.

[0048] Poly-γ-glutamic acid was purchased from Nanjing Xuankai Biotechnology Co., Ltd.

[0049] The zeolite powder was purchased from Jinan Guanghui Chemical Co., Ltd., with a particle size of approximately 300 μm.

[0050] Rhamnose glycolipids were purchased from Shaanxi Deguan Biotechnology Co., Ltd., and are in solid powder form.

[0051] It should be noted that, unless otherwise specified, all parts mentioned in the following embodiments are by weight, and the specific weights mentioned are only examples. In actual production, the weights can be increased proportionally as needed.

[0052] Example 1

[0053] A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate is prepared from the following raw materials in parts by weight: 20 parts polyaluminum chloride, 15 parts polyferric sulfate, 12 parts composite microbial flora, 8 parts adsorption enhancer, 1 part rhamnolipid, and 3 parts poly-γ-glutamic acid.

[0054] The preparation of the composite microbial community includes the following steps:

[0055] S11. Dissolve 5g of polylactic acid in 50mL of dichloromethane to form an organic phase; then add 10g of modified zeolite to the organic phase and ultrasonically disperse it evenly to obtain a mixture; next, add an aqueous solution containing 1wt% polyvinyl alcohol dropwise to the mixture at a volume ratio of 1:8, stir and heat until the dichloromethane is completely evaporated, and finally wash and dry to obtain the carrier;

[0056] S12. According to the dosage of 1g:8mL, the carrier obtained in step S11 is added to the dopamine solution (dopamine hydrochloride is added to Tris-HCl buffer with a pH of 8.5 and the concentration is controlled at 2mg / mL to obtain the carrier). The carrier is stirred and reacted for 12h under the protection of light and at room temperature. After washing and drying, the modified carrier is obtained.

[0057] S13. Add to the mixed bacterial suspension (total viable count not less than 1×10⁻⁶) 10 The mixed bacterial composition (CFU / g, specifically a mixture of Nitrifying Bacillus, Pseudomonas mendoza, and Bacillus subtilis in a 1:1:1 ratio of viable cells) was added to the modified carrier obtained in step S12, followed by shaking incubation at 30°C for 24 hours, and finally filtered and freeze-dried to obtain the composite microbial community; wherein the ratio of the mixed bacterial suspension to the modified carrier was 20 mL : 1 g.

[0058] In step S11, the preparation of the modified zeolite powder includes the following steps: 10g of zeolite powder is added to 45mL of 1.5mol / L hydrochloric acid solution, stirred at 60℃ for 4h, and then washed and dried to obtain pre-modified zeolite; then the pre-modified zeolite is added to 85wt% ethanol solution, the pH of the system is adjusted to 4.5 with acetic acid, 4% KH550 by mass of the pre-modified zeolite is added, stirred at room temperature and then heated to 70℃, stirred again for 6h; after the treatment is completed, the modified zeolite is obtained by centrifugation, washing and drying.

[0059] The preparation of the adsorption enhancer includes the following steps:

[0060] S21. Preparation of nitrogen-doped biochar: 10g of peanut straw was dried, crushed, and sieved through a 100-mesh sieve. It was then added to 100mL of deionized water, followed by 10g of urea and 5g of potassium bicarbonate. The mixture was heated and stirred at 60℃ for 2h and then dried to obtain a precursor. The precursor was pyrolyzed at 750℃ for 2h under nitrogen protection. After pyrolysis, it was cooled and then soaked in 1mol / L hydrochloric acid solution for 1h. Finally, it was washed with deionized water and dried to obtain nitrogen-doped biochar.

[0061] S22. Add the nitrogen-doped biochar obtained in step S21 to deionized water, disperse it by ultrasonication to obtain a suspension, and control the concentration of the suspension to 20 g / L.

[0062] S23. Add the metal salt solution to the suspension obtained in step S22, and stir at room temperature for 2 hours to obtain a mixed solution; wherein, the preparation of the metal salt solution includes the following steps: weigh magnesium nitrate hexahydrate and aluminum nitrate nonahydrate at a molar ratio of 2:1, add them to deionized water, and stir evenly; the concentration of magnesium nitrate hexahydrate is 0.5 mol / L; the volume ratio of metal salt solution to suspension is 2:1;

[0063] Under heating conditions of S24 and 65℃, 50wt% sodium phytate intercalation solution was slowly added dropwise to the mixture obtained in step S23. During the dropwise addition, the pH of the system was adjusted to about 9.5 using 2mol / L sodium hydroxide solution. After the dropwise addition was completed, the mixture was stirred at a constant temperature of 65℃ for 2 hours. After the reaction was completed, the mixture was transferred to a reactor for hydrothermal reaction (120℃, 8 hours). After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the adsorption enhancer. The preparation of the sodium phytate intercalation solution included the following steps: preparing a 50wt% phytic acid aqueous solution, and then adjusting the pH to about 9.0 using 2mol / L sodium hydroxide solution.

[0064] The preparation of the composite wastewater treatment agent includes the following steps: premixing polyaluminum chloride and polyferric sulfate, adding rhamnolipid, stirring at 40°C, then adding adsorption enhancer and poly-γ-glutamic acid, and stirring again; cooling to room temperature, then dry mixing in the composite microbial community, stirring evenly, and it is ready.

[0065] Example 2

[0066] A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate is prepared from the following raw materials in parts by weight: 18 parts polyaluminum chloride, 16 parts polyferric sulfate, 10 parts composite microbial flora, 9 parts adsorption enhancer, 0.8 parts rhamnolipid, and 2.6 parts poly-γ-glutamic acid.

[0067] The preparation of the composite microbial community includes the following steps:

[0068] S11. Dissolve 5g of polylactic acid in 55mL of dichloromethane to form an organic phase; then add 10g of modified zeolite to the organic phase and ultrasonically disperse it evenly to obtain a mixture; next, add an aqueous solution containing 1wt% polyvinyl alcohol dropwise to the mixture at a volume ratio of 1:7, stir and heat until the dichloromethane is completely evaporated, and finally wash and dry to obtain the carrier.

[0069] S12. According to the dosage of 1g:9mL, the carrier obtained in step S11 is added to the dopamine solution (dopamine hydrochloride is added to Tris-HCl buffer with a pH of 8.5 and the concentration is controlled at 2mg / mL to obtain the carrier). The carrier is stirred and reacted for 12h under the protection of light and at room temperature. After washing and drying, the modified carrier is obtained.

[0070] S13. Add to the mixed bacterial suspension (total viable count not less than 1×10⁻⁶) 10 The CFU / g mixed bacterial composition (specifically, a mixture of Nitrifying Bacillus, Pseudomonas mendoza, and Bacillus subtilis in a 1:1:1 ratio of viable cells) was added to the modified carrier obtained in step S12, followed by shaking incubation at 30°C for 24 hours, and finally filtered and freeze-dried to obtain the composite microbial community; wherein the ratio of the mixed bacterial suspension to the modified carrier was 18 mL : 1 g.

[0071] In step S11, the preparation of the modified zeolite powder includes the following steps: 10g of zeolite powder is added to 50mL of 1.6mol / L hydrochloric acid solution, stirred at 60℃ for 3.5h, then washed and dried to obtain pre-modified zeolite; then the pre-modified zeolite is added to 85wt% ethanol solution, the pH of the system is adjusted to 4.5 with acetic acid, 3.8% KH550 by mass of the pre-modified zeolite is added, stirred at room temperature and then heated to 70℃, stirred again for 6h; after the treatment is completed, the modified zeolite is obtained by centrifugation, washing and drying.

[0072] The preparation of the adsorption enhancer includes the following steps:

[0073] S21. Preparation of nitrogen-doped biochar: 10g of dried and crushed peanut straw was sieved through a 100-mesh sieve and added to 100mL of deionized water. Then, 10g of urea and 5g of potassium bicarbonate were added. The mixture was heated and stirred at 60℃ for 2.5h and then dried to obtain a precursor. The precursor was pyrolyzed at 750℃ for 2h under nitrogen protection. After pyrolysis, it was cooled and then soaked in 1.2mol / L hydrochloric acid solution for 0.5h. Finally, it was washed with deionized water and dried to obtain nitrogen-doped biochar.

[0074] S22. Add the nitrogen-doped biochar obtained in step S21 to deionized water, disperse it by ultrasonication to obtain a suspension, and control the concentration of the suspension to 18 g / L.

[0075] S23. Add the metal salt solution to the suspension obtained in step S22, and stir at room temperature for 2 hours to obtain a mixed solution; wherein, the preparation of the metal salt solution includes the following steps: weigh magnesium nitrate hexahydrate and aluminum nitrate nonahydrate at a molar ratio of 2:1, add them to deionized water, and stir evenly; the concentration of magnesium nitrate hexahydrate is 0.45 mol / L; the volume ratio of metal salt solution to suspension is 2:1;

[0076] Under heating conditions of S24 and 65℃, 50wt% sodium phytate intercalation solution was slowly added dropwise to the mixture obtained in step S23. During the dropwise addition, the pH of the system was adjusted to about 9.5 using 2mol / L sodium hydroxide solution. After the dropwise addition was completed, the mixture was stirred at a constant temperature of 65℃ for 3 hours. After the reaction was completed, the mixture was transferred to a reactor for hydrothermal reaction (120℃, 8 hours). After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the adsorption enhancer. The preparation of the sodium phytate intercalation solution included the following steps: preparing a 50wt% phytic acid aqueous solution, and then adjusting the pH to about 9.0 using 2mol / L sodium hydroxide solution.

[0077] The preparation of the composite wastewater treatment agent includes the following steps: premixing polyaluminum chloride and polyferric sulfate, adding rhamnolipid, stirring at 40°C, then adding adsorption enhancer and poly-γ-glutamic acid, and stirring again; cooling to room temperature, then dry mixing in the composite microbial community, stirring evenly, and it is ready.

[0078] Example 3

[0079] A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate is prepared from the following raw materials in parts by weight: 22 parts polyaluminum chloride, 16 parts polyferric sulfate, 10 parts composite microbial flora, 7 parts adsorption enhancer, 1.2 parts rhamnolipid, and 2.8 parts poly-γ-glutamic acid.

[0080] The preparation of the composite microbial community includes the following steps:

[0081] S11. Dissolve 5g of polylactic acid in 50mL of dichloromethane to form an organic phase; then add 10g of modified zeolite to the organic phase and ultrasonically disperse it evenly to obtain a mixture; next, add an aqueous solution containing 1wt% polyvinyl alcohol dropwise to the mixture at a volume ratio of 1:9, stir and heat until the dichloromethane is completely evaporated, and finally wash and dry to obtain the carrier;

[0082] S12. According to the dosage of 1g:9mL, the carrier obtained in step S11 is added to the dopamine solution (dopamine hydrochloride is added to Tris-HCl buffer with a pH of 8.5 and the concentration is controlled at 2mg / mL to obtain the carrier). The carrier is stirred and reacted for 16h under the protection of light and at room temperature. After washing and drying, the modified carrier is obtained.

[0083] S13. Add to the mixed bacterial suspension (total viable count not less than 1×10⁻⁶) 10 The CFU / g mixed bacterial composition (specifically, a mixture of Nitrifying Bacillus, Pseudomonas mendoza, and Bacillus subtilis in a 1:1:1 ratio of viable cells) was added to the modified carrier obtained in step S12, followed by shaking incubation at 30°C for 18 hours, and finally filtered and freeze-dried to obtain the composite microbial community; wherein the ratio of the mixed bacterial suspension to the modified carrier was 22 mL : 1 g.

[0084] In step S11, the preparation of the modified zeolite powder includes the following steps: 10g of zeolite powder is added to 40mL of 1.4mol / L hydrochloric acid solution, stirred at 60℃ for 5h, and then washed and dried to obtain pre-modified zeolite; then the pre-modified zeolite is added to 85wt% ethanol solution, the pH of the system is adjusted to 4.5 with acetic acid, 4.5% KH550 by mass of the pre-modified zeolite is added, stirred at room temperature and then heated to 70℃, stirred again for 6h; after the treatment is completed, the modified zeolite is obtained by centrifugation, washing and drying.

[0085] The preparation of the adsorption enhancer includes the following steps:

[0086] S21. Preparation of nitrogen-doped biochar: 10g of dried and crushed peanut straw was sieved through a 100-mesh sieve and added to 100mL of deionized water. Then, 10g of urea and 5g of potassium bicarbonate were added. The mixture was heated and stirred at 60℃ for 2h and then dried to obtain a precursor. The precursor was pyrolyzed at 745℃ for 2.5h under nitrogen protection. After pyrolysis, it was cooled and then soaked in 1.2mol / L hydrochloric acid solution for 1.5h. Finally, it was washed with deionized water and dried to obtain nitrogen-doped biochar.

[0087] S22. Add the nitrogen-doped biochar obtained in step S21 to deionized water, disperse it by ultrasonication to obtain a suspension, and control the concentration of the suspension to 20 g / L.

[0088] S23. Add the metal salt solution to the suspension obtained in step S22, and stir at room temperature for 2 hours to obtain a mixed solution; wherein, the preparation of the metal salt solution includes the following steps: weigh magnesium nitrate hexahydrate and aluminum nitrate nonahydrate at a molar ratio of 2:1, add them to deionized water, and stir evenly; the concentration of magnesium nitrate hexahydrate is 0.55 mol / L; the volume ratio of metal salt solution to suspension is 2:1;

[0089] Under heating conditions of S24 and 65℃, 50wt% sodium phytate intercalation solution was slowly added dropwise to the mixture obtained in step S23. During the dropwise addition, the pH of the system was adjusted to about 9.5 using 2mol / L sodium hydroxide solution. After the dropwise addition was completed, the mixture was stirred at a constant temperature of 65℃ for 2 hours. After the reaction was completed, the mixture was transferred to a reactor for hydrothermal reaction (120℃, 8 hours). After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the adsorption enhancer. The preparation of the sodium phytate intercalation solution included the following steps: preparing a 50wt% phytic acid aqueous solution, and then adjusting the pH to about 9.0 using 2mol / L sodium hydroxide solution.

[0090] The preparation of the composite wastewater treatment agent includes the following steps: premixing polyaluminum chloride and polyferric sulfate, adding rhamnolipid, stirring at 40°C, then adding adsorption enhancer and poly-γ-glutamic acid, and stirring again; cooling to room temperature, then dry mixing in the composite microbial community, stirring evenly, and it is ready.

[0091] Comparative Example 1

[0092] Compared with Example 1, the modification of zeolite powder was omitted in Comparative Example 1, that is, the raw material zeolite powder was used directly in step S11, and the rest were the same.

[0093] Comparative Example 2

[0094] Compared with Example 1, step S12 was omitted in Comparative Example 2, the carrier was not modified with dopamine, other steps were adjusted accordingly, and the rest were the same.

[0095] Comparative Example 3

[0096] Compared with Example 1, steps S22 to S24 are omitted in Comparative Example 3, that is, only nitrogen-doped biochar is used as an adsorption enhancer, and other steps are adjusted accordingly, while the rest are the same.

[0097] Comparative Example 4

[0098] Compared with Example 1, the use of nitrogen-doped biochar was omitted in Comparative Example 4, that is, only intercalated modified metal salts were used as adsorption enhancers, and other steps were adjusted accordingly, while the rest were the same.

[0099] Comparative Example 5

[0100] Compared with Example 1, the treatment of sodium phytate intercalation solution was omitted in Comparative Example 5, and other steps were adjusted accordingly, while the rest were the same.

[0101] Referring to patent document CN120647099A, the performance of the polyaluminum chloride-based composite wastewater treatment agents prepared in Example 1 and Comparative Examples 1-5 was tested. The specific method is as follows: K2Cr2O7 was added to pure tap water, so that Cr 6+ The concentration of the phosphate ion was 100 mg / L; ammonium chloride was added to make the ammonium ion concentration 40 mg / L; potassium dihydrogen phosphate was added to make the phosphate ion concentration 40 mg / L, and an appropriate amount of glucose was added. After stirring evenly, simulated wastewater was prepared. Then, equal amounts of the above simulated wastewater were taken, and the polyaluminum chloride-based composite wastewater treatment agents prepared in Example 1 and Comparative Examples 1-5 were added at 0.15 g / L respectively. The mixture was stirred at 40 rpm for 5 min, and all experimental groups were kept under the same conditions. Samples were then taken immediately to measure phosphate ions, ammonium ions, and Cr. 6+ The content of the above substances was calculated to obtain the removal rate; after stopping stirring, the mixture was allowed to stand for 3 hours, and the content of the above substances was measured again. Phosphate ions, ammonium ions, and Cr... 6+ The detection was performed using a spectrophotometer, a common method that can be employed, and will not be elaborated upon here. The test results are shown in Table 1.

[0102] Table 1 Removal rate results for each substance

[0103]

[0104] As can be seen from Table 1, the composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate prepared in this embodiment of the invention can achieve a treatment effect equivalent to 3 hours within 5 minutes, indicating that it is effective in treating wastewater (removing ammonium ions, phosphate ions, and Cr). 6+ The high efficiency indicates that the efficient chelation of poly-γ-glutamic acid and rhamnolipin and the flocculation and trapping of PAC / PFS in this invention can rapidly enrich and fix free pollutants in water in a very short time. In addition, the modified adsorption enhancer with a high specific surface area and intercalation trapping capacity also promotes the rapid adsorption of pollutants.

[0105] On the other hand, the treatment effect of 3 hours is relatively better than that of 5 minutes, indicating that the composite wastewater treatment agent prepared by this invention can maintain the stability of the treatment agent through the synergistic effect of each component and has a certain long-term treatment capacity. The above-mentioned long-term effect is due to the structure formed by the polylactic acid skeleton and dopamine modification, which not only blocks heavy metal ions and bacteria, but also forms an extremely stable microenvironment with strong pH buffering capacity inside the composite microorganisms, perfectly protecting the core dormant bacteria from heavy metal poisoning. When the bacteria (Nitrifying Bacillus, Pseudomonas mendoza and Bacillus subtilis) start to work, they can rapidly metabolize and degrade the adsorbed ammonia nitrogen and organic matter.

[0106] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate, characterized in that, It is prepared by weight from the following raw materials: 15-25 parts polyaluminum chloride, 10-20 parts polyferric sulfate, 10-18 parts complex microbial flora, 5-12 parts adsorption enhancer, 0.5-1.5 parts rhamnolipid, and 2-5 parts poly-γ-glutamic acid.

2. The composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 1, characterized in that, The preparation of the composite microbial community includes the following steps: S11. Polylactic acid is dissolved in dichloromethane to form an organic phase; then modified zeolite is added to the organic phase and ultrasonically dispersed to obtain a mixture; next, an aqueous solution containing polyvinyl alcohol is added dropwise to the mixture, stirred and heated until the dichloromethane is completely evaporated, and finally washed and dried to obtain the carrier. S12. Add the carrier obtained in step S11 to the dopamine solution, stir and react under light-protected conditions, and then wash and dry to obtain the modified carrier. S13. Add the modified carrier obtained in step S12 to the mixed bacterial suspension, then shake and incubate, and finally filter and freeze dry to obtain the composite microbial community.

3. The composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 2, characterized in that, In step S11, the ratio of polylactic acid, dichloromethane, and modified zeolite is 2-8g: 40-60mL: 5-15g; the concentration of the aqueous solution containing polyvinyl alcohol is 0.5-1.5wt%; and the volume ratio of the mixed solution to the aqueous solution containing polyvinyl alcohol is 1:5-10. The preparation of the modified zeolite powder includes the following steps: adding zeolite powder to a 1-2 mol / L hydrochloric acid solution, stirring at 50-65°C, and then washing and drying to obtain pre-modified zeolite; The pre-modified zeolite was then added to a 75-90 wt% ethanol solution, and the pH of the system was adjusted to 4.0-5.0 with acetic acid. 3-5% KH550 by weight of the pre-modified zeolite was added, and the mixture was stirred at room temperature and then heated to 65-75℃ and stirred again for 4-8 hours. After the treatment was completed, the modified zeolite was obtained by centrifugation, washing and drying.

4. The composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 2, characterized in that, In step S12, the preparation of the dopamine solution includes the following steps: adding dopamine hydrochloride to a Tris-HCl buffer solution with a pH of 8.2-8.7, and controlling the concentration at 0.5-4 mg / mL; The ratio of carrier to dopamine solution is 1g: 5~10mL; The stirring reaction was carried out at room temperature for 8 to 24 hours.

5. The composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 2, characterized in that, In step S13, the total viable count of the mixed bacterial suspension is not less than 1×10⁻⁶. 10 CFU / g; The mixed bacteria were obtained by mixing Nitrifying Bacillus, Pseudomonas mendoza and Bacillus subtilis in a live count ratio of 1:1:1; The shaking incubation temperature is 25~35℃, and the incubation time is 12~36h.

6. The composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 1, characterized in that, The preparation of the adsorption enhancer includes the following steps: S21. Preparation of nitrogen-doped biochar; S22. Add the nitrogen-doped biochar obtained in step S21 to deionized water and disperse it by ultrasonication to obtain a suspension. S23. Add the metal salt solution to the suspension obtained in step S22 and stir at room temperature for 0.5 to 4 hours to obtain a mixed solution. S24. Under heating conditions, sodium phytate intercalation solution is slowly added dropwise to the mixture obtained in step S23. During the dropwise addition, the pH value of the system is adjusted by sodium hydroxide solution. After the dropwise addition is completed, the reaction is continued to be carried out at a constant temperature with stirring. After the reaction is completed, the mixture is transferred to a reactor for hydrothermal reaction. After the reaction is completed, the mixture is cooled, centrifuged, washed, and dried to obtain the adsorption enhancer.

7. A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 6, characterized in that, In step S21, the preparation of nitrogen-doped biochar includes the following steps: drying and crushing straw, sieving it through an 80-150 mesh sieve, adding it to deionized water, then adding urea and potassium bicarbonate, heating and stirring, and drying to obtain the precursor; wherein, the mass ratio of straw, urea, and potassium bicarbonate is 1:0.8-1.2:0.4-0.

6. The precursor was pyrolyzed at 730-765℃ for 1-4 hours under nitrogen protection. After pyrolysis, it was cooled and then soaked in 0.5-1.5 mol / L hydrochloric acid solution. Finally, it was washed with deionized water and dried to obtain nitrogen-doped biochar.

8. A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 6, characterized in that, In step S22, the concentration of the suspension is 10~30 g / L; In step S23, the preparation of the metal salt solution includes the following steps: weigh magnesium nitrate hexahydrate and aluminum nitrate nonahydrate at a molar ratio of 2:1, add them to deionized water, and stir until homogeneous; the concentration of magnesium nitrate hexahydrate is 0.5~1 mol / L. The volume ratio of the metal salt solution to the suspension is 2:0.8~1.

5.

9. A composite wastewater treatment agent containing polyaluminum chloride and polyferric sulfate according to claim 6, characterized in that, In step S24, the preparation of sodium phytate intercalation solution includes the following steps: preparing a phytic acid aqueous solution with a concentration of 40~60wt%, and then adjusting the pH to 9.0~9.5 with a 1.6~2.5mol / L sodium hydroxide solution; The heating temperature is 55~70℃; the pH value of the system is controlled at 9.5~10.0; the constant temperature stirring reaction time is 1~4h; the hydrothermal reaction temperature is 110~130℃, and the reaction time is 6~24h.

10. A method for preparing the composite wastewater treatment agent according to any one of claims 1 to 9, characterized in that, The process includes the following steps: premixing polyaluminum chloride and polyferric sulfate, adding rhamnolipid, stirring at 35~45℃, then adding adsorption enhancer and poly-γ-glutamic acid, and stirring again; cooling to room temperature, then dry-mixing in the composite microbial flora, stirring evenly, and it is ready.

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