Stable and efficient phosphorus reduction process treatment method

Abstract

The invention provides a stable and efficient phosphorus reduction process treatment method, and relates to the technical field of wastewater phosphorus reduction. The method specifically comprises the following steps: firstly, carrying out primary treatment: introducing the phosphorus-containing wastewater into a primary reaction tank, and adding a primary metal salt solution into the primary reaction tank for reaction; after the reaction, the wastewater flows to a first-stage flocculation basin, and a flocculant solution is added into the first-stage flocculation basin for a flocculation reaction; finally, the wastewater flows to a sedimentation tank to be subjected to sedimentation separation to obtain primary treated wastewater; introducing the first-stage treated wastewater into a second-stage reaction tank, and adding a second-stage metal salt solution into the second-stage reaction tank for reaction; after the reaction, the wastewater flows to a second-stage flocculation basin, and a flocculant solution is added into the second-stage flocculation basin for a flocculation reaction; finally, the wastewater flows to a sedimentation tank to be subjected to sedimentation separation to obtain treated wastewater. The phosphorus content, the solid content and the content of magnesium ammonium phosphate which is not easy to degrade in the obtained treated wastewater are relatively low, and an excellent effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater phosphorus reduction, and in particular to a stable and efficient phosphorus reduction process treatment method. Background Art

[0002] Phosphorus exists in the form of phosphate in wastewater. An appropriate amount of phosphate can play an anti-corrosion role and is also a necessary substance for most aquatic plants and animals. However, excessive phosphate in water can cause eutrophication of water bodies. If the phosphorus content in the water body cannot be controlled within the standard range, this eutrophication of water bodies will have a great negative impact on human survival and the environment. In recent years, with the rapid development of the electronic semiconductor industry, the electronics industry has become one of the main sources of phosphorus-containing wastewater. As environmental emission standards become more and more stringent, the conventional treatment method for phosphorus-containing wastewater is: using a chemical precipitation process to remove phosphorus. The removal rate of a single chemical precipitation process is not high, and it is difficult to stably meet the low-phosphorus emission requirements. Therefore, there is an urgent need for a treatment method that can reduce the phosphorus content in phosphorus-containing wastewater to improve water utilization. Summary of the invention

[0003] The purpose of the present invention is to provide a stable and efficient phosphorus reduction process treatment method so as to better degrade phosphorus-containing wastewater, meet low-phosphorus emission requirements and improve water utilization.

[0004] In order to solve the above technical problems, the present invention specifically provides the following technical solutions: The present invention discloses a stable and efficient phosphorus reduction process method, comprising: S1: The phosphorus-containing wastewater is passed into the primary reaction tank to react with the primary metal salt solution; after the reaction, it flows to the primary flocculation tank to react with the flocculant solution; finally, it flows to the primary sedimentation tank to obtain the primary treated wastewater after sedimentation and separation; S2: The primary treated wastewater obtained in S1 is passed into the secondary reaction tank to react with the secondary metal salt solution; after the reaction, it flows to the secondary flocculation tank to react with the flocculant solution; finally, it flows to the secondary sedimentation tank to obtain treated wastewater after sedimentation separation; the flocculant solution is obtained by adding a flocculant to water, and the flocculant is at least one of polyacrylamide and a composite flocculant. The use of the composite flocculant can better combine with the phosphate particles generated in the phosphorus-containing wastewater to form larger particles, improve the efficiency of precipitation, reduce the phosphorus content of the treated wastewater, and reduce the solid content in the treated wastewater and the content of magnesium ammonium phosphate that is not easily degradable.

[0005] Preferably, the primary reaction tank in S1 includes a primary reaction tank 1 and a primary reaction tank 2.

[0006] Preferably, the phosphorus value of the phosphorus-containing wastewater in S1 is 2000-2200 mg / L; the primary metal salt solution is a calcium salt solution, the volume ratio of the amount of calcium salt solution used in the primary reaction tank 1 to the amount of phosphorus-containing wastewater is 1:35-48, and the volume ratio of the amount of calcium salt solution used in the primary reaction tank 2 to the amount of phosphorus-containing wastewater is 1:245-300.

[0007] Preferably, the primary metal salt solution in S1 is a calcium salt solution, and the volume ratio of the calcium salt solution used to the amount of phosphorus-containing wastewater is 1:35-48.

[0008] Preferably, the phosphorus value of the primary treated wastewater in S2 is 10-20 mg / L.

[0009] Preferably, the secondary metal salt solution in S2 is at least one of an aluminum salt solution, an iron salt solution, a polyaluminum-iron solution or a lanthanum salt solution.

[0010] Preferably, the volume ratio of the aluminum salt solution used in S2 to the amount of primary treated wastewater is 1:1100-1850, the volume ratio of the iron salt solution used to the amount of primary treated wastewater is 1:1100-1800, the volume ratio of the polyaluminum-iron solution used to the amount of primary treated wastewater is 1:9000-15000, and the volume ratio of the lanthanum salt solution used to the amount of primary treated wastewater is 1:2100-2800.

[0011] Preferably, the flocculant solution in S1 or S2 is obtained by adding flocculant to water, and the amount of flocculant added to water is 0.7-1.3 g / L; the volume ratio of the amount of flocculant solution used in S1 to the amount of phosphorus-containing wastewater is 1:0.3-0.6, and the volume ratio of the amount of flocculant solution used in S2 to the amount of primary treated wastewater is 1:32-55.

[0012] Preferably, the reaction time in S1 is 10-50 min, the reaction pH is adjusted to 7-10 by sodium hydroxide and sulfuric acid, and the flocculation reaction time is 8-15 min.

[0013] Preferably, the reaction time in S2 is 10-20 min, the reaction pH is adjusted to 7-10 by sodium hydroxide, sulfuric acid and aluminate solution; and the flocculation reaction time is 8-15 min.

[0014] The present invention discloses a stable and efficient phosphorus reduction process method, comprising: S1: Primary treatment: The phosphorus-containing wastewater is passed into the primary reaction tank, and a primary metal salt solution is added to the primary reaction tank for reaction; after the reaction, it flows to the primary flocculation tank, and a flocculant solution is added to the primary flocculation tank for flocculation reaction; finally, it flows to the sedimentation tank for sedimentation separation to obtain primary treated wastewater; S2: Secondary treatment: The primary treated wastewater obtained in S1 is passed into the secondary reaction tank, into which a secondary metal salt solution is added for reaction; after the reaction, it flows to the secondary flocculation tank, into which a flocculant solution is added for flocculation reaction; finally, it flows to the sedimentation tank, through sedimentation separation, to obtain treated wastewater.

[0015] Preferably, the phosphorus value of the phosphorus-containing wastewater is 2000-2200 mg / L.

[0016] Preferably, the primary reaction tank in S1 includes a primary reaction tank 1 and a primary reaction tank 2.

[0017] More preferably, the primary metal salt solution in S1 is a calcium salt solution, the volume ratio of the amount of calcium salt solution used in the primary reaction tank 1 to the amount of phosphorus-containing wastewater is 1:35-48, and the volume ratio of the amount of calcium salt solution used in the primary reaction tank 2 to the amount of phosphorus-containing wastewater is 1:245-300.

[0018] More preferably, the calcium salt solution is obtained by adding calcium salt into water, the amount of calcium salt added into water is 200-400 g / L, and the calcium salt is calcium chloride.

[0019] Preferably, the phosphorus value of the primary treated wastewater in S2 is 10-20 mg / L.

[0020] Preferably, the metal salt solution in S2 is at least one of an aluminum salt solution, an iron salt solution, a polyaluminum-iron solution or a lanthanum salt solution.

[0021] More preferably, the aluminum salt solution is obtained by adding aluminum salt into water, the amount of aluminum salt added into water is 100-400 g / L, and the aluminum salt is at least one of polyaluminum chloride solution and aluminum sulfate solution.

[0022] More preferably, the iron salt solution is obtained by adding an iron salt into water, the amount of the iron salt added into the water is 100-300 g / L, and the iron salt is at least one of a ferric chloride solution and a polyferric sulfate solution.

[0023] More preferably, the polyaluminum-iron solution is obtained by adding polyaluminum-iron to water, the amount of polyaluminum-iron added to water is 100-300 g / L, and the polyaluminum-iron is at least one of polyaluminum-iron chloride, polyaluminum-iron sulfate and polyaluminum-iron bisulfate.

[0024] More preferably, the lanthanum salt solution is obtained by adding a lanthanum salt to water, the amount of the lanthanum salt added to the water is 250-350 g / L, and the lanthanum salt is lanthanum chloride.

[0025] More preferably, the volume ratio of the amount of aluminum salt solution used to the amount of primary treated wastewater is 1:1100-1850.

[0026] More preferably, the volume ratio of the amount of the iron salt solution used to the amount of the primary treated wastewater is 1:1100-1800.

[0027] More preferably, the volume ratio of the amount of polyaluminum-ferroic solution used to the amount of primary treated wastewater is 1:9000-15000.

[0028] More preferably, the volume ratio of the amount of lanthanum salt solution used to the amount of primary treated wastewater is 1:2100-2800.

[0029] Preferably, the flocculant solution in S1 or S2 is obtained by adding the flocculant into water, and the amount of the flocculant added into the water is 0.7-1.3 g / L.

[0030] Preferably, the flocculant is at least one of polyacrylamide and a composite flocculant.

[0031] Preferably, the volume ratio of the amount of flocculant solution used in S1 to the amount of phosphorus-containing wastewater is 1:0.3-0.6.

[0032] Preferably, the volume ratio of the amount of flocculant solution used in S2 to the amount of primary treated wastewater is 1:32-55.

[0033] Preferably, the reaction time in S1 is 10-50 min, the reaction pH is adjusted to 7-10 by sodium hydroxide and sulfuric acid, and the flocculation reaction time is 8-15 min.

[0034] Preferably, the reaction time in S2 is 10-20 min, the reaction pH is adjusted to 7-10 by sodium hydroxide, sulfuric acid and aluminate solution; and the flocculation reaction time is 8-15 min.

[0035] The invention also discloses the preparation of the composite flocculant, comprising: First, chitosan is added to an acetic acid solution and mixed, and N,N-bis(2-hydroxyethyl)methacrylamide and sodium methacrylate sulfonate are added, and ammonium cerium nitrate is added under nitrogen conditions for reaction. After the reaction is completed, chitosan polymer is obtained by precipitation washing and vacuum drying; then polyaluminum chloride and water are added to the chitosan polymer to mix to obtain a composite liquid, and the composite liquid is dried and ground to obtain a composite coagulant.

[0036] Preferably, the acetic acid solution consists of acetic acid and water, and the volume ratio of the amount of water used to the amount of acetic acid used is 1:0.00026.

[0037] Preferably, the amount of chitosan added to the acetic acid solution is 1.8-2.3 g / L.

[0038] Preferably, the mass ratio of the amount of chitosan used to the amount of N,N-bis(2-hydroxyethyl)methacrylamide used is 1:0.2-0.3.

[0039] Preferably, the mass ratio of the amount of chitosan used to the amount of sodium methyl methacrylate sulfonate used is 1:0.2-0.3.

[0040] Preferably, the mass ratio of the amount of chitosan used to the amount of ammonium cerium nitrate used is 1:0.0002-0.0004.

[0041] Preferably, the mass ratio of the amount of chitosan polymer used to the amount of polyaluminium chloride used is 1:4-5.5.

[0042] Preferably, the amount of polyaluminium chloride in water is 48-51 g / L.

[0043] Preferably, the reaction temperature is 55-65°C and the reaction time is 4.5-6h.

[0044] More preferably, in the secondary treatment process, on the basis of using the composite flocculant solution, a carboxylic acid organosilicon salt solution can also be used. The addition of the carboxylic acid organosilicon salt solution can be used in conjunction with the composite flocculant solution to enhance the adhesion of phosphate particles in the wastewater, further agglomerate them, and make the agglomerates more compact, thereby promoting precipitation, further reducing the phosphorus content of the treated wastewater, reducing the solid content in the treated wastewater and the content of magnesium ammonium phosphate that is not easily degradable, and having excellent effects.

[0045] Preferably, the carboxylic acid organosilicon salt solution is obtained by adding carboxylic acid organosilicon salt to water, the amount of carboxylic acid organosilicon salt added to water is 0.7-1.3 g / L, and the volume ratio of the carboxylic acid organosilicon salt solution to the composite flocculant solution is 1:1.5-5.

[0046] The invention discloses the preparation of carboxylic acid organosilicon salt, comprising: First, vinylmethyldichlorosilane and trimethylchlorosilane are mixed, and isopropanol is added dropwise for reaction, and then water is added dropwise for continuous reaction. After the reaction is completed, the organic layer is separated, and the organic silicon precursor is obtained by washing, removing water and vacuum distillation. The organic silicon precursor, thioglycolic acid and tetrahydrofuran are mixed, and 2,2-dimethoxy-phenylacetophenone is added, and the reaction is carried out under ultraviolet light, and then sodium carbonate is added for continuous reaction. After the reaction is completed, the carboxylic acid organic silicon salt is obtained by rotary evaporation, washing and drying.

[0047] Preferably, vinylmethyldichlorosilane and trimethylchlorosilane are mixed in a mass ratio of 1:3.5-4.5.

[0048] Preferably, the mass ratio of the amount of isopropanol used to the amount of vinylmethyldichlorosilane used is 1:0.3-0.43.

[0049] Preferably, the mass ratio of the amount of water used to the amount of vinylmethyldichlorosilane used is 0.8-0.92.

[0050] Preferably, the mass ratio of the amount of the organosilicon precursor to the amount of the thioglycolic acid is 1:1-1.8.

[0051] Preferably, the mass ratio of the amount of the organosilicon precursor to the amount of tetrahydrofuran is 1:0.3-0.5.

[0052] Preferably, the mass ratio of the amount of the organosilicon precursor to the amount of 2,2-dimethoxy-phenylacetophenone is 1:0.02-0.034.

[0053] Preferably, the mass ratio of the amount of the organosilicon precursor used to the amount of the sodium carbonate used is 1:0.17-0.25.

[0054] Preferably, after adding isopropanol, the reaction temperature is 2-5°C and the reaction time is 0.8-1.2h.

[0055] Preferably, the reaction time after adding water is 1-2 hours.

[0056] Preferably, the reaction time after adding 2,2-dimethoxy-phenylacetophenone is 15 minutes.

[0057] Preferably, the reaction time after adding sodium carbonate is 1.5-2.3h.

[0058] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a stable and efficient phosphorus reduction process treatment method. First, primary treatment is performed: phosphorus-containing wastewater is passed into a primary reaction tank, a primary metal salt solution is added to the primary reaction tank for reaction; after the reaction, it flows to a primary flocculation tank, a flocculant solution is added to the primary flocculation tank for flocculation reaction; finally, it flows to a sedimentation tank for sedimentation separation to obtain primary treated wastewater; the primary treated wastewater is passed into a secondary reaction tank, a secondary metal salt solution is added to the secondary reaction tank for reaction; after the reaction, it flows to a secondary flocculation tank, a flocculant solution is added to the secondary flocculation tank for flocculation reaction; finally, it flows to a sedimentation tank for sedimentation separation to obtain treated wastewater. The phosphorus content, solid content and non-degradable magnesium ammonium phosphate content in the treated wastewater finally obtained are all low, and have excellent effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0060] Figure 1 This is the infrared spectrum characterization analysis diagram of chitosan polymer; Figure 2 This is a graph showing the results of the phosphorus content measurement in the treated wastewater; Figure 3 This is the result diagram of solid content measurement of treated wastewater; Figure 4 This is a diagram for determining the magnesium ammonium phosphate content in treated wastewater. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0063] Embodiment 1: Primary treatment: the phosphorus-containing wastewater is passed into the primary reaction tank 1, and calcium chloride solution is added to the primary reaction tank 1 to react for 15 minutes; after the reaction, it flows to the primary reaction tank 2, and calcium chloride solution is added to the primary reaction tank 2 to react for another 15 minutes; then it flows to the primary flocculation tank, and polyacrylamide solution is added to the primary flocculation tank, and the flocculation reaction is carried out for 10 minutes; finally, it flows to the sedimentation tank for sedimentation and separation to obtain the primary treated wastewater. The phosphorus value of the phosphorus-containing wastewater is 2000 mg / L; the calcium chloride solution is obtained by adding calcium chloride into water, the amount of calcium chloride added into water is 300 g / L, the volume ratio of the amount of calcium chloride solution added into the primary reaction tank 1 to the amount of phosphorus-containing wastewater is 1:45.71, and sodium hydroxide and sulfuric acid are added into the primary reaction tank 1 to adjust the pH to 9; the volume ratio of the amount of calcium chloride solution added into the primary reaction tank 2 to the amount of phosphorus-containing wastewater is 1:320, and sodium hydroxide and sulfuric acid are added into the primary reaction tank 2 to adjust the pH to 8; the polyacrylamide solution is obtained by adding polyacrylamide into water, the amount of polyacrylamide added into water is 1 g / L, and the volume ratio of the amount of polyacrylamide solution added into the primary flocculation tank to the amount of phosphorus-containing wastewater is 1:0.5; when the phosphorus value of the phosphorus-containing wastewater after reaction in the primary reaction tank 1 is ≤20 mg / L, it flows directly into the primary flocculation tank.

[0064] Secondary treatment: the primary treated wastewater is passed into the secondary reaction tank, and aluminum sulfate solution is added to the secondary reaction tank for reaction for 15 minutes; after the reaction, it flows to the secondary flocculation tank, and polyacrylamide solution is added to the secondary flocculation tank for flocculation reaction for 10 minutes; finally, it flows to the sedimentation tank for sedimentation and separation to obtain treated wastewater. The phosphorus value of the primary treated wastewater is 20 mg / L; the aluminum sulfate solution is obtained by adding aluminum sulfate to water, the amount of aluminum sulfate added to water is 300 g / L, and the volume ratio of the amount of aluminum sulfate solution added to the secondary reaction tank to the amount of primary treated wastewater is 1:1699; sodium hydroxide, sulfuric acid and aluminate solution are added to the secondary reaction tank to adjust the pH to 6.8; the polyacrylamide solution is obtained by adding polyacrylamide to water, the amount of polyacrylamide added to water is 1 g / L, and the volume ratio of the amount of polyacrylamide solution added to the secondary flocculation tank to the amount of primary treated wastewater is 1:50.

[0065] Embodiment 2: The primary treatment is the same as in Example 1.

[0066] Secondary treatment: the primary treated wastewater is passed into the secondary reaction tank, and ferric chloride solution is added to the secondary reaction tank for reaction for 15 minutes; after the reaction, it flows to the secondary flocculation tank, and polyacrylamide solution is added to the secondary flocculation tank for flocculation reaction for 10 minutes; finally, it flows to the sedimentation tank for sedimentation and separation to obtain treated wastewater. The phosphorus value of the primary treated wastewater is 20 mg / L; the ferric chloride solution is obtained by adding ferric chloride to water, the amount of ferric chloride added to water is 200 g / L, and the volume ratio of the amount of ferric chloride solution added to the secondary reaction tank to the amount of primary treated wastewater is 1:1675; sodium hydroxide, sulfuric acid and aluminate solution are added to the secondary reaction tank to adjust the pH to 6.8; polyacrylamide solution is obtained by adding polyacrylamide to water, the amount of polyacrylamide added to water is 1 g / L, and the volume ratio of the amount of polyacrylamide solution added to the secondary flocculation tank to the amount of primary treated wastewater is 1:50.

[0067] Embodiment 3: The primary treatment is the same as in Example 1.

[0068] Secondary treatment: the primary treated wastewater is passed into the secondary reaction tank, and aluminum sulfate solution and polyaluminum ferric chloride solution are added to the secondary reaction tank to react for 40 minutes; after the reaction, it flows to the secondary flocculation tank, and polyacrylamide solution is added to the secondary flocculation tank to flocculate for 4 hours; finally, it flows to the sedimentation tank for sedimentation and separation to obtain treated wastewater. The phosphorus value of the primary treated wastewater is 20 mg / L; the aluminum sulfate solution is obtained by adding aluminum sulfate to water, the amount of aluminum sulfate added to water is 300 g / L, and the volume ratio of the amount of aluminum sulfate solution added to the secondary reaction tank to the amount of primary treated wastewater is 1:1699; the polyaluminum ferric chloride solution is obtained by adding polyaluminum ferric chloride to water, the amount of polyaluminum ferric chloride added to water is 300 g / L, and the volume ratio of the amount of polyaluminum ferric chloride solution added to the secondary reaction tank to the amount of primary treated wastewater is 1:12000; sodium hydroxide, sulfuric acid and aluminate solution are added to the secondary reaction tank to adjust the pH to 6.8; the polyacrylamide solution is obtained by adding polyacrylamide to water, the amount of polyacrylamide added to water is 1 g / L, and the volume ratio of the amount of polyacrylamide solution added to the secondary flocculation tank to the amount of primary treated wastewater is 1:50.

[0069] Embodiment 4: The primary treatment is the same as in Example 1.

[0070] Secondary treatment: the primary treated wastewater is passed into the secondary reaction tank, into which aluminum sulfate solution and lanthanum chloride solution are added for reaction for 15 minutes; after the reaction, it flows to the secondary flocculation tank, into which polyacrylamide solution is added for flocculation reaction for 10 minutes; finally, it flows to the sedimentation tank for sedimentation and separation to obtain treated wastewater. The phosphorus value of the primary treated wastewater is 20 mg / L; the aluminum sulfate solution is obtained by adding aluminum sulfate to water, the amount of aluminum sulfate added to water is 300 g / L, and the volume ratio of the amount of aluminum sulfate solution added to the secondary reaction tank to the amount of primary treated wastewater is 1:1699; the lanthanum chloride solution is obtained by adding lanthanum chloride to water, the amount of lanthanum chloride added to water is 300 g / L, and the volume ratio of the amount of lanthanum chloride solution added to the secondary reaction tank to the amount of primary treated wastewater is 1:2560; sodium hydroxide, sulfuric acid and aluminate solution are added to the secondary reaction tank to adjust the pH to 6.8; the polyacrylamide solution is obtained by adding polyacrylamide to water, the amount of polyacrylamide added to water is 1 g / L, and the volume ratio of the amount of polyacrylamide solution added to the secondary flocculation tank to the amount of primary treated wastewater is 1:50.

[0071] Embodiment 5: Preparation of composite flocculant: chitosan is added to acetic acid solution and mixed, and N, N-bis (2-hydroxyethyl) methacrylamide and sodium methacryl sulfonate are added after mixing, and then ammonium cerium nitrate is added under nitrogen conditions, and the reaction is carried out at 60 ° C for 5 hours. After the reaction is completed, chitosan polymer is obtained by precipitation washing and vacuum drying; then polyaluminum chloride and water are added to the chitosan polymer to mix to obtain a composite liquid, and the composite liquid is dried and ground to obtain a composite coagulant. The acetic acid solution consists of acetic acid and water, the volume ratio of water to acetic acid is 1:0.00026, the amount of chitosan added to the acetic acid solution is 1.95 g / L, the mass ratio of chitosan to N,N-bis(2-hydroxyethyl)methacrylamide is 1:0.25, the mass ratio of chitosan to sodium methyl methacrylate sulfonate is 1:0.25, the mass ratio of chitosan to ammonium cerium nitrate is 1:0.0003, the mass ratio of chitosan polymer to polyaluminium chloride is 1:5, and the amount of polyaluminium chloride in water is 50 g / L.

[0072] The primary treatment is the same as in Example 1.

[0073] Secondary treatment: The secondary treatment in this embodiment is different from that in Example 1 in that the polyacrylamide solution replaces the composite flocculant solution, the composite flocculant solution is obtained by adding the composite flocculant prepared in this embodiment to water, the amount of the composite flocculant added to the water is 1 g / L, the volume ratio of the amount of the composite flocculant solution added to the secondary flocculation tank to the amount of the primary treated wastewater is 1:50, and other conditions and parameters are the same as in Example 4.

[0074] Embodiment 6: The preparation of the composite flocculant is the same as in Example 5.

[0075] The primary treatment is the same as in Example 1.

[0076] Secondary treatment: The difference between the secondary treatment in this embodiment and that in Example 5 is that the volume ratio of the amount of the composite flocculant solution added to the secondary flocculation tank to the amount of the primary treated wastewater is 1:40, and the other conditions and parameters are the same as in Example 5.

[0077] Embodiment 7: The preparation of the composite flocculant is the same as in Example 5.

[0078] Preparation of carboxylic acid organosilicon salt: Vinylmethyldichlorosilane and trimethylchlorosilane were mixed, and isopropanol was added dropwise to react at 4°C for 1 hour, and then water was added dropwise to continue the reaction for 1.5 hours. After the reaction, the organic layer was separated, and the organosilicon precursor was obtained by washing, removing water and vacuum distillation. The organosilicon precursor, thioglycolic acid and tetrahydrofuran were mixed, and 2,2-dimethoxy-phenylacetophenone was added, and the reaction was carried out under ultraviolet light for 15 minutes, and then sodium carbonate was added to continue the reaction for 2 hours. After the reaction, the carboxylic acid organosilicon salt was obtained by rotary evaporation, washing with n-hexane and drying. Vinylmethyldichlorosilane and trimethylchlorosilane are mixed in a mass ratio of 1:3.85, the mass ratio of isopropyl alcohol to vinylmethyldichlorosilane is 1:0.39, the mass ratio of water to vinylmethyldichlorosilane is 0.87, the mass ratio of the amount of silicone precursor to thioglycolic acid is 1:1.3, the mass ratio of the amount of silicone precursor to tetrahydrofuran is 1:0.41, the mass ratio of the amount of silicone precursor to 2,2-dimethoxy-phenylacetophenone is 1:0.028, and the mass ratio of the amount of silicone precursor to sodium carbonate is 1:0.214.

[0079] The primary treatment is the same as in Example 1.

[0080] Secondary treatment: the primary treated wastewater is passed into the secondary reaction tank, and aluminum sulfate solution is added to the secondary reaction tank for reaction for 15 minutes; the primary treated wastewater after the reaction flows to the secondary flocculation tank, and composite flocculant solution and carboxylic acid organosilicon salt solution are added to the secondary flocculation tank for flocculation reaction for 10 minutes; finally, it flows to the sedimentation tank for sedimentation and separation to obtain treated wastewater. The phosphorus value of the primary treated wastewater is 20 mg / L; the aluminum sulfate solution is obtained by adding aluminum sulfate into water, the amount of aluminum sulfate added into water is 300 g / L, and the volume ratio of the amount of aluminum sulfate solution added into the secondary reaction tank to the amount of the primary treated wastewater is 1:1699; sodium hydroxide, sulfuric acid and aluminate solution are added into the secondary reaction tank to adjust the pH to 6.8; the composite flocculant solution is obtained by adding the composite flocculant into water, the amount of the composite flocculant added into water is 1 g / L, and the volume ratio of the amount of the composite flocculant solution added into the secondary flocculation tank to the amount of the primary treated wastewater is 1:50; the carboxylic acid organosilicon salt solution is obtained by adding the carboxylic acid organosilicon salt into water, the amount of the carboxylic acid organosilicon salt added into water is 1 g / L, and the volume ratio of the amount of the carboxylic acid organosilicon salt solution added into the secondary flocculation tank to the amount of the composite flocculant solution is 1:2.

[0081] Embodiment 8: The preparation of the composite flocculant is the same as in Example 5.

[0082] The preparation of carboxylic acid organosilicon salt is the same as in Example 7.

[0083] The primary treatment is the same as in Example 1.

[0084] Secondary treatment: The secondary treatment in this embodiment is different from that in Example 7 in that the volume ratio of the carboxylic acid organosilicon salt solution to the composite flocculant solution added to the secondary flocculation tank is 1:3, and other conditions and parameters are the same as in Example 7.

[0085] Comparative Example 1: The preparation of the composite flocculant is the same as in Example 5.

[0086] The primary treatment is the same as in Example 1.

[0087] Secondary treatment: The difference between the secondary treatment in this embodiment and that in Example 5 is that the volume ratio of the composite flocculant solution added to the secondary flocculation tank to the primary treated wastewater is 1:60, and other conditions and parameters are the same as in Example 5.

[0088] Comparative Example 2: The preparation of the composite flocculant is the same as in Example 5.

[0089] The primary treatment is the same as in Example 1.

[0090] Secondary treatment: The difference between the secondary treatment in this embodiment and that in Example 5 is that the volume ratio of the amount of the composite flocculant solution added to the secondary flocculation tank to the amount of the primary treated wastewater is 1:28, and the other conditions and parameters are the same as in Example 5.

[0091] Experimental Example 1: The chitosan polymer was characterized and the composite flocculant prepared in Example 1 was characterized and analyzed by infrared spectroscopy with a scanning range of 400-4000 cm -1 The results are as follows Figure 1 As shown, 3200-3500 cm -1 is the characteristic absorption peak of OH, 2800-3000 cm -1 is the characteristic absorption peak of -CH3 and -CH2, 1651 cm -1 is the characteristic absorption peak of C=O, 1553 cm -1 is the characteristic absorption peak of NH, 1265 cm -1 is the characteristic absorption peak of S=O, 1074 cm -1 It is the characteristic absorption peak of CN.

[0092] Experimental Example 2: The phosphorus content of the treated wastewater obtained in Examples 1-8 and Comparative Examples 1-2 was measured. Figure 2As shown, the phosphorus content of the treated wastewater in Example 1 of the present invention is higher than that in Examples 3 and 4, indicating that on the basis of using polyaluminum chloride, adding polyaluminum chloride iron or lanthanum chloride can further reduce the phosphorus content of the treated wastewater and improve the phosphorus reduction effect; compared with Example 5, Example 4 shows that the use of a composite flocculant for flocculation treatment can improve the phosphorus reduction effect and reduce the phosphorus content of the treated wastewater; compared with Example 6, Example 5 shows that the phosphorus content of the treated wastewater is still low when the amount of the composite flocculant used is reduced within a certain range; compared with Example 7, Example 5 shows that on the basis of using a composite flocculant, adding a carboxylic acid organosilicon salt can synergistically reduce the phosphorus content of the treated wastewater; compared with Example 7 and Example 8, it shows that the reduction of the amount of the carboxylic acid organosilicon salt used within a certain range will increase the phosphorus content of the treated wastewater; compared with Comparative Examples 1 and 2, Example 5 shows that the amount of the composite flocculant used needs to be in an appropriate range. Too low a content inhibits the reduction of the phosphorus content of the treated wastewater. When the amount used exceeds a certain range, the phosphorus reduction effect will no longer be significantly improved even if the amount used is increased.

[0093] Experimental Example 3: The solid content of the treated wastewater obtained in Examples 1-8 and Comparative Examples 1-2 was measured. Figure 3 As shown, the solid content of the treated wastewater in Example 1 of the present invention is higher than that in Examples 3 and 4, indicating that on the basis of using polyaluminum chloride, adding polyaluminum chloride iron or lanthanum chloride can promote the formation of a stable form of precipitation and reduce the solid content in the treated wastewater after separation; compared with Example 5, Example 4 shows that the use of a composite flocculant for flocculation treatment can improve the flocculation effect, promote precipitation and sedimentation, and reduce the solid content in the treated wastewater after separation; compared with Example 6, Example 5 shows that the solid content in the treated wastewater after precipitation separation is still low when the amount of the composite flocculant used is reduced within a certain range; Compared with Example 7, Example 5 shows that on the basis of using a composite flocculant, adding carboxylic acid organosilicon salt can synergistically promote sedimentation and reduce the solid content in the treated wastewater after separation; compared with Example 8, Example 7 shows that reducing the usage of carboxylic acid organosilicon salt within a certain range will increase the solid content in the treated wastewater; compared with Comparative Examples 1 and 2, Example 5 shows that the usage of the composite flocculant needs to be in an appropriate range. Too low a usage will reduce the coagulation and sedimentation effect, thereby affecting the solid content of the treated wastewater. When the usage exceeds a certain range, increasing the usage will have no obvious effect on reducing the solid content.

[0094] Experimental Example 4: Magnesium ammonium phosphate particles are fine in size and have a density close to that of water. They do not sink in water for a long time and are difficult to handle. The content of magnesium ammonium phosphate in the primary treated wastewater without secondary treatment in Example 1 and the treated wastewater obtained in Examples 1-8 and Comparative Examples 1-2 was measured. The results are as follows: Figure 4As shown, the magnesium ammonium phosphate content of the primary treated wastewater without secondary treatment in Example 1 is used as a control; the magnesium ammonium phosphate content of the treated wastewater in Example 1 of the present invention is higher than that in Examples 3 and 4, indicating that on the basis of using polyaluminum chloride, adding polyaluminum chloride iron or lanthanum chloride can promote the reduction of the magnesium ammonium phosphate content and effective removal; Example 4 is compared with Example 5, indicating that the use of a composite flocculant for flocculation treatment can better reduce the magnesium ammonium phosphate content; Example 5 is compared with Example 6, indicating that a reduction in the use amount of the composite flocculant within a certain range will lead to an increase in the magnesium ammonium phosphate content; Example 5 is compared with Example 7, indicating that on the basis of using a composite flocculant, adding carboxylic acid organic silicon salt can synergistically promote the reduction of the magnesium ammonium phosphate content; Example 7 is compared with Example 8, indicating that a reduction in the use amount of carboxylic acid organic silicon salt within a certain range will increase the magnesium ammonium phosphate content; Example 5 is compared with Comparative Examples 1 and 2, indicating that the use amount of the composite flocculant needs to be in an appropriate range, too low will reduce the removal effect of magnesium ammonium phosphate, and when the use amount exceeds a certain range, increasing the use amount will no longer significantly improve the removal effect of magnesium ammonium phosphate.

[0095] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention. This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A stable and efficient phosphorus reduction process, comprising: S1: Phosphorus-containing wastewater is passed into the primary reaction tank to react with the primary metal salt solution; After the reaction, it flows to the primary flocculation tank to react with the flocculant solution; Finally, it flows to the primary sedimentation tank and undergoes sedimentation separation to obtain primary treated wastewater; S2: The primary treated wastewater obtained in S1 is passed into a secondary reaction tank to react with a secondary metal salt solution; after the reaction, it flows to a secondary flocculation tank to react with a flocculant solution; finally, it flows to a secondary sedimentation tank to obtain treated wastewater after sedimentation separation; the flocculant solution is obtained by adding a flocculant into water, the flocculant is at least one of polyacrylamide and a composite flocculant, and the composite flocculant is prepared from chitosan, N,N-bis(2-hydroxyethyl)methacrylamide, sodium methacrylic acid, ammonium cerium nitrate and polyaluminum ferric chloride.

2. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The primary reaction pool in S1 includes a primary reaction pool 1 and a primary reaction pool 2.

3. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The phosphorus value of the phosphorus-containing wastewater in S1 is 2000-2200 mg / L; the primary metal salt solution is a calcium salt solution, the volume ratio of the amount of calcium salt solution used in the primary reaction tank 1 to the amount of phosphorus-containing wastewater is 1:35-48, and the volume ratio of the amount of calcium salt solution used in the primary reaction tank 2 to the amount of phosphorus-containing wastewater is 1:245-300.

4. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The phosphorus value of the primary treated wastewater in S2 is 10-20 mg / L.

5. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The secondary metal salt solution in S2 is at least one of an aluminum salt solution, an iron salt solution, a polyaluminum-iron solution or a lanthanum salt solution.

6. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The volume ratio of the aluminum salt solution used in S2 to the amount of primary treated wastewater is 1:1100-1850, the volume ratio of the iron salt solution used to the amount of primary treated wastewater is 1:1100-1800, the volume ratio of the polyaluminum-iron solution used to the amount of primary treated wastewater is 1:9000-15000, and the volume ratio of the lanthanum salt solution used to the amount of primary treated wastewater is 1:2100-2800.

7. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The flocculant solution in S1 or S2 is obtained by adding flocculant into water, and the amount of flocculant added into water is 0.7-1.3 g / L; the volume ratio of the amount of flocculant solution used in S1 to the amount of phosphorus-containing wastewater is 1:0.3-0.6, and the volume ratio of the amount of flocculant solution used in S2 to the amount of primary treated wastewater is 1:32-55.

8. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The reaction time in S1 is 10-50 min, the reaction pH is adjusted to 7-10 by sodium hydroxide and sulfuric acid, and the flocculation reaction time is 8-15 min.

9. A stable and efficient phosphorus reduction process according to claim 1, characterized in that: The reaction time in S2 is 10-20 minutes, and the reaction pH is adjusted to 7-10 by sodium hydroxide, sulfuric acid and aluminate solution; the flocculation reaction time is 8-15 minutes.

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