A method for efficiently treating industrial wastewater

Abstract

The application discloses a method for efficiently treating industrial wastewater, and belongs to the technical field of wastewater treatment. The method comprises the following steps: modifying Solidago Canadensis first, preparing a flocculating agent by using the modified Solidago Canadensis, preliminarily separating industrial wastewater in a factory, adding the flocculating agent into a sedimentation tank for repair, and then performing the steps of filtration, pH adjustment and filtration sedimentation treatment to obtain treated wastewater. In the method for treating industrial wastewater, the flocculating agent has better flocculating effect than traditional flocculating agents, has the advantages of weakening toxicity, and can efficiently treat industrial wastewater and is easy to biodegrade.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for efficiently treating industrial wastewater. Background Art

[0002] Domestic sewage, food processing, and industrial wastewater from papermaking contain organic substances such as carbohydrates, proteins, oils, and lignin. These substances exist in suspended or dissolved forms and can be decomposed through the biochemical action of microorganisms. Because they consume oxygen during decomposition, they are called oxygen-consuming pollutants. These pollutants reduce dissolved oxygen in the water, affecting the growth of fish and other aquatic organisms. Once dissolved oxygen is depleted, organic matter undergoes anaerobic decomposition, producing unpleasant odors such as hydrogen sulfide, ammonia, and mercaptans, deteriorating water quality.

[0003] Currently, there are many technologies available internationally for treating industrial wastewater, with flocculation and sedimentation being a common method. In flocculation and sedimentation, flocculants are a key factor in determining the effectiveness of coagulation treatment. Flocculants are classified into three broad categories: inorganic, organic, and microbial. Organic flocculants include synthetic organic polymer flocculants and natural organic polymer flocculants. Synthetic organic flocculants are generally high-molecular polymers, such as polyacrylamide flocculants. However, polyacrylamide exhibits strong neurotoxicity and certain carcinogenicity. When used in large quantities in wastewater treatment, high-molecular-weight residues can be produced, disrupting the aquatic food chain and potentially affecting human health. Natural organic flocculants are often used for wastewater treatment due to their environmental friendliness, non-toxicity, low cost, and readily biodegradable properties. However, these flocculants have disadvantages such as low charge density, low relative molecular weight, and poor flocculation effectiveness.

[0004] Therefore, a method for preparing synthetic organic flocculants using natural organic polymer materials is needed to reduce the toxicity of the polymer materials, improve the efficiency of industrial wastewater treatment, and at the same time, the synthesized organic flocculants are easily biodegradable and have low secondary pollution when used in industrial wastewater treatment. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for efficiently treating industrial wastewater to solve the problems of poor treatment effect during wastewater treatment and toxicity and residue caused after treatment.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A method for efficiently treating industrial wastewater, comprising the following steps:

[0008] (1) Discharge industrial wastewater into the screen channel to separate large suspended solids and floating matter in the wastewater to obtain pretreated industrial wastewater;

[0009] (2) Discharge the pretreated industrial wastewater into a sedimentation tank, add flocculants for repair, and filter to obtain filtered industrial wastewater;

[0010] (3) The filtered industrial wastewater is discharged into the acid-base regulating tank, and the pH of the wastewater in the tank is adjusted to 5.5-7.5 after sterilization and disinfection to obtain industrial wastewater with adjusted pH value;

[0011] (4) The industrial wastewater after pH adjustment is passed into an aerated grit chamber for treatment, and then passed into a bioreactor for treatment. The wastewater is discharged and filtered and settled to obtain treated industrial wastewater.

[0012] Furthermore, the flocculant in step (2) comprises the following raw materials: 20-30 parts by mass of modified Solidago canadensis, 5-6 parts by mass of sodium alginate, 0.5-0.8 parts by mass of quaternary ammonium starch ether, 4-9 parts by mass of acrylic acid, 2-5 parts by mass of sodium lauryl sulfate, and 10-13 parts by mass of pentaerythritol.

[0013] Furthermore, the flocculant is prepared by the following steps:

[0014] (1) Dissolving the modified Canada goldenrod in water to form a solution, adding sodium lauryl sulfate, pentaerythritol and acrylic acid and stirring, mixing and stirring uniformly at 40°C for 30-60 minutes, adding sodium hydroxide solution dropwise to the obtained paste, adjusting the pH value to 7, washing and drying to obtain a reactant;

[0015] (2) Sodium alginate, a small amount of water and quaternary ammonium starch ether are added to the above reactants, stirred at a speed of 1200-1400 r / min and then crushed to obtain a flocculant.

[0016] Furthermore, the modified Canada goldenrod includes the following raw materials: 20-35 parts by mass of Canada goldenrod, 16-20 parts by mass of polyacrylamide, 3-5 parts by mass of dicyclohexylcarbodiimide, 0.1-0.2 parts by mass of ammonium persulfate, 0.1-0.2 parts by mass of N,N'-methylenebisacrylamide, 11-17 parts by mass of cyclohexyl methacrylate, 0.1-0.3 parts by mass of tert-butyl peroxy-2-ethylhexanoate, and 4-8 parts by mass of an organic solvent.

[0017] Furthermore, the specific modification steps of the Canada solidago are:

[0018] (1) Crush the Canada goldenrod through a 100-mesh sieve, soak it in anhydrous ethanol and 1 wt% sodium hydroxide solution at room temperature for 24 h, wash it with deionized water until the pH is neutral, filter and dry it, then add it into water, heat it to 60-70 ° C and stir it for 30-40 min, then add ammonium persulfate, polyacrylamide and N,N'-methylenebisacrylamide, stir and mix it for 1-2 h to obtain an intermediate product;

[0019] (2) The intermediate product is dissolved in an organic solvent, dicyclohexylcarboximide is added and mixed, ultrasonicated for 20-25 minutes, heated to 55-80°C and reacted for 20-30 hours, cooled to room temperature, then added with anhydrous ethanol, allowed to stand and filtered, the filtered precipitate is washed and dried to obtain an intermediate, the intermediate, cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate are mixed, added to an organic solvent at 125-140°C, reacted at 125-140°C for 2-3 hours, and the modified Canada goldenrod is obtained.

[0020] Furthermore, the organic solvent in the preparation step (1) of the modified Solidago canadensis is toluene.

[0021] Canada goldenrod was first dissolved in a mixed solution containing sodium hydroxide to remove excess impurities. Because Canada goldenrod contains numerous reactive groups, such as hydroxyl groups, it imparts a negative surface charge, which can chelate and adsorb impurity particles in the water, agglomerating the particles into flocs. This exhibits a limited adsorption and flocculation effect, but this adsorption capacity is weak and only works within a certain pH range. Therefore, ammonium persulfate, polyacrylamide, and N,N'-methylenebisacrylamide were added to the surface of Canada goldenrod, allowing the Canada goldenrod and polyacrylamide to bind to form an intermediate product. The surface charge of the intermediate product varied at different pH values, and its zeta potential gradually decreased with increasing pH, shifting from positive to negative, resulting in excellent adsorption and flocculation across a wide pH range. The intermediate product was then reacted with dicyclohexylcarboximide, which added numerous active sites, further enhancing its rapid response to impurity atoms and phosphorus and nitrogen, effectively removing phosphate and nitrogen salts dissolved in industrial wastewater. The addition of cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate destabilizes organic and inorganic particles through a bridging flocculent reaction, significantly increasing the flocculation rate of the modified Solidago canadensis. The modified Solidago canadensis is then grafted onto the surface with sodium lauryl sulfate, pentaerythritol, and acrylic acid to form a three-dimensional network structure that better captures and fixes flocs, making them difficult to dislodge. The flocculant is then bonded to a quaternary ammonium starch ether with sodium alginate to produce a flocculant that captures even more pollutants. Beneficial effects

[0022] (1) Flocculants can reduce toxicity while efficiently treating industrial wastewater and are easy to biodegrade to remove suspended solids, phosphorus and other pollutants in the water.

[0023] (2) The method can effectively purify and repair industrial wastewater by using the flocculant prepared by the present invention. At the same time, the water purification process of the present invention method does not generate secondary pollution and is harmless to water bodies and organisms. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the embodiments:

[0025] 1. Preparation of modified Solidago canadensis

[0026] The present invention provides a flocculant for treating industrial wastewater and a preparation method thereof. However, before preparing the flocculant, modified Solidago canadensis needs to be prepared first. The raw materials of the modified Solidago canadensis prepared in the present invention are weighed according to the data in Table 1, and the specific proportions are as follows:

[0027] Table 1

[0028] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Canada goldenrod (g) 28 20 35 0 28 28 Polyacrylamide (g) 18 16 20 18 18 18 Dicyclohexylcarboimide (g) 4 3 5 4 0 4 Ammonium persulfate (g) 0.15 0.1 0.2 0.15 0.15 0.15 N,N'-Methylenebisacrylamide (g) 0.15 0.1 0.2 0.15 0.15 0.15 Cyclohexyl methacrylate (g) 14 11 17 14 14 0 Tert-butyl peroxy-2-ethylhexanoate (g) 0.2 0.1 0.3 0.2 0.2 0 Toluene (mL) 6 4 8 6 6 6

[0029] The specific preparation processes of Examples 1-3 and Comparative Examples 1-3 are as follows:

[0030] Example 1: Preparation of modified Solidago canadensis

[0031] (1) Canada goldenrod was crushed through a 100-mesh sieve, soaked in anhydrous ethanol and 1 wt% sodium hydroxide solution at room temperature for 24 h, filtered, washed with deionized water until the pH was neutral, dried at 50 ° C, added to water, heated to 65 ° C and stirred for 35 min, and then ammonium persulfate, polyacrylamide and N, N'-methylenebisacrylamide were added and stirred for 1.5 h to obtain an intermediate product;

[0032] (2) The intermediate product was dissolved in toluene, and dicyclohexylcarboximide was added and mixed. The mixture was ultrasonicated at 30 kHz for 23 minutes, heated to 67°C and reacted for 25 hours. The mixture was cooled to room temperature, and then anhydrous ethanol was added and allowed to stand for 2 hours before filtering. The filtered precipitate was washed and dried to obtain an intermediate. The intermediate, cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate were mixed and added to toluene at 133°C. The mixture was reacted at 133°C for 2.5 hours to obtain modified Canada goldenrod.

[0033] Example 2: Preparation of modified Solidago canadensis

[0034] (1) Crush the Canada goldenrod through a 100-mesh sieve, soak it in anhydrous ethanol and 1 wt% sodium hydroxide solution at room temperature for 24 h, filter it, wash it with deionized water until the pH is neutral, dry it at 50 ° C, add it into water, heat it to 60 ° C and start stirring. After stirring for 40 min, add ammonium persulfate, polyacrylamide and N,N'-methylenebisacrylamide, and stir and mix for 1 h to obtain an intermediate product;

[0035] (2) The intermediate product was dissolved in toluene, and dicyclohexylcarboximide was added and mixed. The mixture was ultrasonicated at 30 kHz for 20 minutes, heated to 80°C and reacted for 20 hours. The mixture was cooled to room temperature, and then anhydrous ethanol was added and allowed to stand for 2 hours before filtering. The filtered precipitate was washed and dried to obtain an intermediate. The intermediate, cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate were mixed and added to toluene at 140°C. The mixture was reacted at 140°C for 2 hours to obtain modified Canada goldenrod.

[0036] Example 3: Preparation of modified Solidago canadensis

[0037] (1) Canada goldenrod was crushed and passed through a 100-mesh sieve, soaked in anhydrous ethanol and 1 wt% sodium hydroxide solution at room temperature for 24 h, filtered, washed with deionized water until the pH was neutral, dried at 50 ° C, added to water, heated to 70 ° C and stirred for 30 min, and then ammonium persulfate, polyacrylamide and N, N'-methylenebisacrylamide were added and stirred for 2 h to obtain an intermediate product;

[0038] (2) The intermediate product was dissolved in toluene, and dicyclohexylcarboximide was added and mixed. The mixture was ultrasonicated at 30 kHz for 25 minutes, heated to 55°C and reacted for 30 hours. The mixture was cooled to room temperature, and then anhydrous ethanol was added and allowed to stand for 2 hours before filtering. The filtered precipitate was washed and dried to obtain an intermediate. The intermediate, cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate were mixed and added to toluene at 125°C. The mixture was reacted at 125°C for 3 hours to obtain modified Canada goldenrod.

[0039] Comparative Example 1: Preparation of modified Canada goldenrod

[0040] The step (2) of this comparative example is the same as that of Example 1, except for the step (1):

[0041] (1) Heat water to 65°C, add ammonium persulfate, polyacrylamide and N,N'-methylenebisacrylamide, and stir for 1.5 hours to obtain an intermediate product.

[0042] Comparative Example 2: Preparation of modified Canada goldenrod

[0043] The step (1) of this comparative example is the same as that of Example 1, except for the step (2):

[0044] (2) The intermediate product was dissolved in toluene, ultrasonicated at 30 kHz for 23 min, heated to 67 °C and reacted for 25 h, cooled to room temperature, and then added with anhydrous ethanol and allowed to stand for 2 h before filtering. The filtered precipitate was washed and dried to obtain an intermediate. The intermediate, cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate were mixed and added to toluene at 133 °C. The mixture was reacted at 133 °C for 2.5 h to obtain modified Canada goldenrod.

[0045] Comparative Example 3: Preparation of modified Canada goldenrod

[0046] The step (1) of this comparative example is the same as that of Example 1, except for the step (2):

[0047] (2) The intermediate product was dissolved in toluene, and dicyclohexylcarboximide was added and mixed. After ultrasonication at 30 kHz for 23 minutes, the mixture was heated to 67°C and reacted for 25 hours. The mixture was cooled to room temperature, and then anhydrous ethanol was added and allowed to stand for 2 hours before filtering. The filtered precipitate was washed and dried to obtain an intermediate. The intermediate was added to toluene at 133°C and reacted at 133°C for 2.5 hours to obtain modified Canada goldenrod.

[0048] 2. Preparation of flocculants

[0049] The raw materials used in the following examples and comparative examples were weighed according to the following table, and the modified Solidago canadensis used was prepared as in Example 1:

[0050] Table 2 (unit: g)

[0051] Modified Solidago canadensis Sodium alginate Quaternary ammonium starch ether acrylic acid Sodium lauryl sulfate Pentaerythritol Example 4 25 (Example 1) 5.5 0.6 7 4 12 Example 5 20 (Example 1) 5 0.5 4 2 10 Example 6 30 (Example 1) 6 0.8 9 5 13 Comparative Example 4 25 (Canada goldenrod) 5.5 0.6 7 4 12 Comparative Example 5 0 5.5 0.6 7 4 12 Comparative Example 6 25 (Example 1) 5.5 0.6 0 4 0 Comparative Example 7 25 (Example 1) 5.5 0.6 7 0 12

[0052] The preparation steps of each embodiment and comparative example are as follows:

[0053] Example 4: Preparation of flocculant

[0054] (1) The modified Solidago canadensis was dissolved in water to form a solution, sodium lauryl sulfate, pentaerythritol and acrylic acid were added, and the mixture was uniformly stirred at 40°C for 45 minutes to obtain a paste. Sodium hydroxide solution was added dropwise to the obtained paste, and the pH value thereof was adjusted to 7, and then washed and dried to obtain a reactant;

[0055] (2) Sodium alginate, 5 g of water and quaternary ammonium starch ether were added to the above reactants, stirred rapidly at a speed of 1300 r / min, and then crushed to obtain a flocculant.

[0056] Example 5: Preparation of flocculant 2

[0057] (1) The modified Solidago canadensis was dissolved in water to form a solution, sodium lauryl sulfate, pentaerythritol and acrylic acid were added, and the mixture was uniformly stirred at 40°C for 30 minutes to obtain a paste. Sodium hydroxide solution was added dropwise to the obtained paste, and the pH value was adjusted to 7, followed by washing and drying to obtain a reactant;

[0058] (2) Sodium alginate, 5 g of water and quaternary ammonium starch ether were added to the above reactants, stirred rapidly at a speed of 1200 r / min, and then crushed to obtain a flocculant.

[0059] Example 6: Preparation of flocculant 3

[0060] (1) The modified Solidago canadensis was dissolved in water to form a solution, sodium lauryl sulfate, pentaerythritol and acrylic acid were added, and the mixture was uniformly stirred at 40°C for 60 minutes to obtain a paste. Sodium hydroxide solution was added dropwise to the obtained paste, and the pH value thereof was adjusted to 7, and then washed and dried to obtain a reactant;

[0061] (2) Sodium alginate, 5 g of water and quaternary ammonium starch ether were added to the above reactants, stirred rapidly at a speed of 1400 r / min, and then crushed to obtain a flocculant.

[0062] Comparative Example 4: Preparation of flocculant

[0063] The steps of Comparative Example 4 are the same as those of Example 4.

[0064] Comparative Example 5: Preparation of flocculant

[0065] The step (2) of Comparative Example 5 is the same as that of Example 4, except for the step (1):

[0066] (1) Sodium lauryl sulfate, pentaerythritol, and acrylic acid were added to water, and the mixture was uniformly stirred at 40° C. for 45 minutes to obtain a paste. Sodium hydroxide solution was added dropwise to the obtained paste, and the pH value thereof was adjusted to 7, and the paste was washed and dried to obtain a reactant.

[0067] Comparative Example 6: Preparation of flocculant

[0068] The step (2) of Comparative Example 6 is the same as that of Example 4, except for the step (1):

[0069] (1) The modified Canada goldenrod was dissolved in water to form a solution, mixed and stirred at 40°C for 45 minutes, and then sodium hydroxide solution was added dropwise. The pH value was adjusted to 7, and then washed and dried to obtain a reactant.

[0070] Comparative Example 7: Preparation of flocculant

[0071] The step (2) of Comparative Example 7 is the same as that of Example 4, except for the step (1):

[0072] (1) The modified Canada goldenrod was dissolved in water to form a solution, pentaerythritol and acrylic acid were added, and the mixture was stirred at 40°C for 45 minutes to obtain a paste. Sodium hydroxide solution was added dropwise to the obtained paste, and the pH value was adjusted to 7, followed by washing and drying to obtain a reactant.

[0073] 3. Treatment of industrial wastewater

[0074] Example 7: Treatment of industrial wastewater

[0075] The specific steps are as follows:

[0076] (1) Discharge industrial wastewater into the screen channel, adjust the pH of the industrial wastewater to 6-8, the water load is 3000-4500 mg / L, the screen gap at the water inlet is 18-24 mm, and the screen gap at the water outlet is 5-12 mm. The large suspended solids and floating solids in the wastewater are separated and filtered through the screen channel to obtain pretreated industrial wastewater;

[0077] (2) Discharge the pretreated industrial wastewater into the sedimentation tank, add flocculant at a dosage of 0.1g / L, stir slowly to fully mix the industrial wastewater and flocculant, then let it stand for repair, and then separate the precipitate and clear liquid to obtain filtered industrial wastewater;

[0078] (3) The filtered industrial wastewater is discharged into an acid-base regulating tank, first disinfected with a mixture of bleaching powder and dichloramine, then stirred and mixed for 20-40 minutes, and then the pH is adjusted to 5.5-7.5 with hydrochloric acid to obtain industrial wastewater with adjusted pH value;

[0079] (4) The pH-adjusted industrial wastewater is passed into an aerated grit chamber for treatment, with a residence time of 20-40 minutes and a wastewater flow rate of 0.08-0.12 m / s. It is then passed into a bioreactor and aerated for 2-3 hours while the water is flowing in. The water flow is then closed to stop aeration and anaerobic treatment is performed for 1-2 hours. Finally, the wastewater is discharged for filtration and sedimentation to obtain the treated industrial wastewater.

[0080] Experiment 1: Treatment of industrial wastewater with flocculants

[0081] 1. Preparation method:

[0082] Experimental group: In experimental group 1, the flocculant was prepared by the preparation method of Example 4, wherein the modified Solidago canadensis was prepared according to Example 1.

[0083] Control group: Comparative groups 1-3 were prepared using the method of Example 6, but the modified Solidago canadensis was selected from the modified Solidago canadensis prepared in Comparative Examples 1-3 respectively;

[0084] Comparative groups 4-8 were prepared using the method of Comparative Examples 4-8, wherein the modified Solidago canadensis was prepared according to Example 1.

[0085] Blank control group: No flocculant was added to the blank control group when treating industrial wastewater.

[0086] 2. Specific experimental methods:

[0087] Each group of flocculants was prepared into a treatment solution with a mass fraction of 0.5% for standby use, with a total of 10 groups. 1 mL of the prepared flocculant solution was added to 400 mL of wastewater, and the mixture was stirred at a speed of 300 r / min for 10 minutes. After stopping, the shape and sedimentation rate of the flocs were observed. After standing for 30 minutes, the supernatant was taken to measure the turbidity. Turbidity can reflect the optical properties of suspended particles in water, can detect the efficiency of suspended solids removal in industrial wastewater, and is the main indicator for measuring water quality. The turbidity of industrial wastewater was measured on a turbidimeter according to GB 13200-1991. The results are shown in Table 3:

[0088] Table 3

[0089] Oil removal rate / % Turbidity removal rate / % Example 4 80.19 90.31 Comparative Example 1 60.44 64.53 Comparative Example 2 72.58 85.34 Comparative Example 3 68.67 80.48 Comparative Example 4 56.93 59.86 Comparative Example 5 54.36 55.74 Comparative Example 6 62.38 68.98 Comparative Example 7 65.32 76.41 Blank control 10.21 9.82

[0090] The treated industrial wastewater of each group was used to determine the ammonia nitrogen content in the wastewater using the Nessler reagent spectrophotometry method (HJ 535-2009), the total phosphorus content in the wastewater was determined using the ammonium molybdate spectrophotometry method (GB 11893-89), the total nitrogen content in the wastewater was determined using the alkaline potassium persulfate digestion ultraviolet spectrophotometry method (HJ 636-2012), and the COD content in the wastewater was determined using the rapid digestion spectrophotometry method (HJ / T 399-2007). The results are shown in Table 4:

[0091] Table 4

[0092] Ammonia nitrogen content (mg / L) Total phosphorus content (mg / L) Total nitrogen content (mg / L) COD content (mg / L) Example 4 0.65 0.26 1.32 9.12 Comparative Example 1 1.52 0.37 1.94 16.21 Comparative Example 2 0.87 0.31 1.84 13.56 Comparative Example 3 0.92 0.33 1.87 14.88 Comparative Example 4 1.76 0.38 1.95 17.51 Comparative Example 5 2.04 0.42 1.99 20.33 Comparative Example 6 1.48 0.36 1.91 15.97 Comparative Example 7 1.01 0.34 1.89 15.62 Blank control 12.37 17.64 2.86 164.37

[0093] According to the data analysis in Table 3-4:

[0094] 1. Example 4 achieved an oil removal rate of 80.19% and a turbidity removal rate of 90.31% for industrial wastewater. The oil removal rate of Comparative Example 1 was 19.75% lower than that of Example 4, and the turbidity removal rate was 25.78% lower. The ammonia nitrogen content in the industrial wastewater treated by Example 4 was only 0.65 mg / L, the total phosphorus content and total nitrogen content were 0.26 mg / L and 1.32 mg / L, respectively, and the COD content was 9.12 mg / L. The ammonia nitrogen content of Comparative Example 1 is 0.87 mg / L higher than that of Example 4, the total phosphorus content and total nitrogen content are 0.11 mg / L and 0.62 mg / L higher, and the COD content is increased by 7.09 mg / L. In Comparative Example 1, no Canada thistle was added, and only a small amount of polyacrylamide was used to prepare the flocculant. Therefore, the oil removal rate and turbidity removal rate were lower than those of Example 4. Oil-water and turbidity are important indicators for intuitively measuring the effect of wastewater treatment. Therefore, the water purification effect of the flocculant prepared in Comparative Example 1 is not as ideal as that of the flocculant prepared in Example 4.

[0095] 2. The oil removal rates of Comparative Examples 2 and 3 were 7.61% and 11.52% lower than those of Example 4, respectively, and the turbidity removal rates were reduced by 4.97% and 9.83%, respectively; the ammonia nitrogen content of Comparative Example 2 was 0.22 mg / L higher than that of Example 4, the total phosphorus content and the total nitrogen content were 0.05 mg / L and 0.52 mg / L higher, and the COD content increased by 4.44 mg / L; the ammonia nitrogen content of Comparative Example 3 was 0.27 mg / L higher than that of Example 4, the total phosphorus content and the total nitrogen content were 0.07 mg / L and 0.55 mg / L higher, and the COD content increased by 5.76 mg / L. Comparative Example 2 did not add dicyclohexylcarboximide, and the active sites of Canada thistle were not as abundant as those in Example 4, and could not quickly respond to impurity atoms in the water. Comparative Example 3 did not add cyclohexyl methacrylate and tert-butyl peroxy-2-ethylhexanoate, so the flocculant lacked the corresponding bridging flocculation reaction to capture particulate matter in the wastewater. Therefore, Example 4, which has high active sites and can produce a bridging flocculation reaction, can play a better role.

[0096] 3. The oil removal rate of Comparative Example 4 was 23.26% lower than that of Example 4, and the turbidity removal rate was 30.45% lower. The oil removal rate of Comparative Example 5 was 25.83% lower than that of Example 4, and the turbidity removal rate was 34.57% lower. The ammonia nitrogen content of Comparative Example 4 was 1.11 mg / L higher than that of Example 4, and the total phosphorus content and total nitrogen content were 0.12 mg / L and 0.63 mg / L higher, respectively, and the COD content increased by 8.39 mg / L. The ammonia nitrogen content of Comparative Example 5 was 1.39 mg / L higher than that of Example 4, and the total phosphorus content and total nitrogen content were 0.16 mg / L and 0.67 mg / L higher, respectively, and the COD content increased by 11.21 mg / L. Comparative Example 4 directly added Solidago canadensis to prepare the flocculant, while Comparative Example 5 did not add Solidago canadensis, and the two had the worst effects.

[0097] 4. The oil removal rate of Comparative Example 6 was 17.81% lower than that of Example 4, and the turbidity removal rate was 21.33% lower. The oil removal rate of Comparative Example 7 was 14.87% lower than that of Example 4, and the turbidity removal rate was 13.9% lower. The ammonia nitrogen content of Comparative Example 6 was 0.83 mg / L higher than that of Example 4, and the total phosphorus content and total nitrogen content were 0.1 mg / L and 0.59 mg / L higher, respectively, and the COD content increased by 6.85 mg / L. The ammonia nitrogen content of Comparative Example 7 was 0.36 mg / L higher than that of Example 4, and the total phosphorus content and total nitrogen content were 0.08 mg / L and 0.57 mg / L higher, respectively, and the COD content increased by 6.5 mg / L. Comparative Example 6 lacks sodium lauryl sulfate, acrylic acid, and pentaerythritol. Acrylic acid and pentaerythritol can form a three-dimensional network structure on the surface of the flocculant to better capture and fix flocs. Therefore, the turbidity removal rate and oil removal rate of the flocculant in the comparative example are poor, and even if flocs are captured, they are not easy to fix for a long time.

[0098] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and such modifications or equivalents shall be encompassed by the claims of the present invention. Any techniques, shapes, and structures not described in detail herein are well known.

Claims

1. A method for efficiently treating industrial wastewater, characterized in that: The steps of the method are: (1) Discharge industrial wastewater into the screen channel to separate large suspended solids and floating matter in the wastewater to obtain pretreated industrial wastewater; (2) Discharge the pretreated industrial wastewater into a sedimentation tank, add flocculants for repair, and filter to obtain filtered industrial wastewater; (3) The filtered industrial wastewater is discharged into the acid-base regulating tank, and the pH of the wastewater in the tank is adjusted to 5.5-7.5 after sterilization and disinfection to obtain industrial wastewater with adjusted pH value; (4) The pH-adjusted industrial wastewater is passed through an aerated grit chamber for treatment, and then passed through a bioreactor for treatment. The wastewater is discharged and filtered and sedimented to obtain treated industrial wastewater. The flocculant in step (2) includes the following raw materials: 20-30 parts by mass of modified Solidago canadensis, 5-6 parts by mass of sodium alginate, 0.5-0.8 parts by mass of quaternary ammonium starch ether, 4-9 parts by mass of acrylic acid, 2-5 parts by mass of sodium lauryl sulfate, and 10-13 parts by mass of pentaerythritol; The modified Canada goldenrod comprises the following raw materials: 20-35 parts by mass of Canada goldenrod, 16-20 parts by mass of polyacrylamide, 3-5 parts by mass of dicyclohexylcarbodiimide, 0.1-0.2 parts by mass of ammonium persulfate, 0.1-0.2 parts by mass of N,N'-methylenebisacrylamide, 11-17 parts by mass of cyclohexyl methacrylate, 0.1-0.3 parts by mass of tert-butyl peroxy-2-ethylhexanoate, and 4-8 parts by mass of an organic solvent; The specific modification steps of the Canada solidago are: (1) Crush the Canada goldenrod through a 100-mesh sieve, soak it in a mixed solution at room temperature for 24 hours, wash it with deionized water until the pH is neutral, filter and dry it, then add it into water, heat it to 60-70°C and stir it for 30-40 minutes, then add ammonium persulfate, polyacrylamide and N,N'-methylenebisacrylamide, and stir and mix it for 1-2 hours to obtain an intermediate product; (2) The intermediate product is dissolved in an organic solvent, and dicyclohexylcarboximide is added and mixed. The mixture is heated to 55-80°C after ultrasonic treatment and reacted for 20-30 hours. The mixture is cooled to room temperature, and then anhydrous ethanol is added, allowed to stand, and filtered. The filtered precipitate is washed and dried to obtain an intermediate. The intermediate, cyclohexyl methacrylate, and tert-butyl peroxy-2-ethylhexanoate are mixed and added to an organic solvent at 125-140°C. The mixture is reacted at 125-140°C for 2-3 hours to obtain modified Canada goldenrod.

2. A method for efficiently treating industrial wastewater according to claim 1, characterized in that: The preparation steps of the flocculant are: (1) Dissolving the modified Canada goldenrod in water to form a solution, adding sodium lauryl sulfate, pentaerythritol and acrylic acid and stirring, mixing and stirring uniformly at 40°C for 30-60 minutes, adjusting the pH value of the obtained paste to 7, washing and drying, and obtaining a reactant; (2) Sodium alginate, a small amount of water and quaternary ammonium starch ether are added to the above reactants, stirred rapidly and then crushed to obtain a flocculant.

3. A method for efficiently treating industrial wastewater according to claim 2, characterized in that: The stirring speed in the flocculant preparation step (2) is 1200-1400 r / min.

4. A method for efficiently treating industrial wastewater according to claim 3, characterized in that: The mixed solution in the preparation step (1) of the modified Canada goldenrod is a mixture of anhydrous ethanol and 1w% sodium hydroxide solution.

5. A method for efficiently treating industrial wastewater according to claim 4, characterized in that: The organic solvent in the preparation step (2) of the modified Canada goldenrod is toluene.

6. A method for efficiently treating industrial wastewater according to claim 5, characterized in that: The ultrasonic time in the preparation step (2) of the modified Canada goldenrod is 20-25 minutes and the frequency is 20-40 kHz.