Method for treating rural sewage using natural freezing

Abstract

The application discloses a method for treating rural sewage by using natural freezing, and belongs to the technical field of sewage treatment. The method for treating rural sewage by using natural freezing comprises the following steps: step one, collecting rural sewage, flowing the rural sewage into a grit chamber through a grid for sedimentation, adjusting pH, adding a composite adsorption material for adsorption treatment, and obtaining pretreated rural sewage; step two, adding the pretreated rural sewage into a water storage tank, then discharging the pretreated rural sewage into a treatment tank, connecting a sludge tank to a four-stage treatment tank, using natural cooling to freeze, moving ice bodies in the treatment tank into an ice storage tank, then sequentially discharging sewage into a next-stage treatment tank, and repeating the operation; and step three, after temperature rises, using an ecological floating island technology to treat mixed sewage in the sludge tank, and using ice in the ice storage tank after the ice is dissolved for rural landscape and agricultural irrigation. The method can simply and efficiently treat rural sewage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and particularly relates to a method for treating rural sewage by using natural freezing. BACKGROUND

[0002] With the rapid development of rural economy and the continuous growth of population, the discharge of rural domestic sewage increases, while the corresponding sewage treatment facilities lag behind, leading to untreated sewage being directly discharged into rivers, lakes and other natural water bodies, polluting the rural environment and threatening the safety of rural water supply and ecological balance. In some remote and economically underdeveloped rural areas, due to the limitations of funds, technology and management, it is a great challenge to establish and maintain an efficient sewage treatment system.

[0003] Rural sewage discharge has the characteristics of dispersion, small and fluctuating water quantity, and complex water quality, which makes it difficult to effectively apply the traditional centralized sewage treatment mode. At the same time, rural areas generally lack professional sewage treatment technology and personnel, and are short of funds, making the construction and operation and maintenance cost of sewage treatment facilities high, and difficult to popularize. In addition, the content of organic matter, nitrogen and phosphorus and other pollutants in rural sewage is high, and if not properly treated, it will not only cause water eutrophication, but also affect the growth of crops and soil quality, further exacerbating the deterioration of the rural environment.

[0004] Therefore, it is particularly urgent to explore an economical and efficient sewage treatment method that is suitable for rural characteristics. Under the driving of such demand, the method of treating rural sewage by using natural freezing gradually enters the field of vision as an innovative solution. This method ingeniously uses the natural low temperature conditions in winter in cold regions, combines sewage treatment with the natural environment, and realizes a low-cost, low-energy-consumption and environmentally friendly treatment approach. SUMMARY

[0005] The purpose of the present application is to provide a method for treating rural sewage by using natural freezing, which solves the technical problem of poor rural sewage treatment in the prior art.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] The present application provides a method for treating rural sewage by using natural freezing, comprising the following steps:

[0008] Step one: collect rural sewage through a grid, flow into a sand settling tank for sedimentation, adjust pH, add composite adsorbent material for adsorption treatment, remove the composite adsorbent material after the adsorption treatment is completed, and obtain pretreated rural sewage;

[0009] Step two: the pretreated rural sewage is added into the water storage pool, and then is sequentially discharged into the first-stage treatment pool, the second-stage treatment pool, the third-stage treatment pool and the fourth-stage treatment pool, the fourth-stage treatment pool is connected with the sludge pool, the ice bodies in the first-stage treatment pool, the second-stage treatment pool, the third-stage treatment pool and the fourth-stage treatment pool are moved into the ice storage pool by using natural cooling and freezing, and then the sewage is sequentially discharged into the next-stage treatment pool, and the operation is repeated;

[0010] Step three: after the temperature rises, the mixed sewage in the sludge pool is treated by using the ecological floating island technology, and the ice in the ice storage pool is used for rural landscape and agricultural irrigation after being dissolved.

[0011] Preferably, in the step one, the grid distance of the grid is ≤20mm, the sedimentation time is ≥30min, lime or ferrous sulfate is added to adjust pH=6-8, and the adsorption treatment time is 60-90min.

[0012] Preferably, in the step one, the preparation method of the composite adsorption material comprises the following steps:

[0013] Q1: sodium hyaluronate is added into MES buffer solution, stirred and mixed, then 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride is added, continues to be stirred, then methylaminoacetaldehyde dimethyl acetal is added, heated and stirred, and condensed reflux, after the reflux is completed, dialysis, freeze-drying, and an intermediate is obtained;

[0014] Q2: the intermediate is added into deionized water, acid hydrolysis, pH adjustment, standing, and dialysis, and modified sodium hyaluronate is obtained;

[0015] Q3: polyvinyl alcohol is added into deionized water, heated and stirred to dissolve to obtain a polyvinyl alcohol solution, modified sodium hyaluronate is added into deionized water, stirred and dissolved to obtain a modified sodium hyaluronate solution, polyacrylic acid is added into deionized water, stirred and mixed uniformly to obtain a polyacrylic acid solution, then the polyvinyl alcohol solution, the modified sodium hyaluronate solution and the polyacrylic acid solution are mixed uniformly to obtain an electrospinning solution, and a nanometer membrane is obtained by electrospinning technology, heated and reacted, washed, and freeze-dried to obtain a composite adsorption material.

[0016] In the above process, the synthesis reaction formula of the modified sodium hyaluronate is as follows:

[0017]

[0018] As preferred, in the Q1, the amount ratio of sodium hyaluronate, MES buffer, 4-(4, 6-dimethoxy-1, 3, 5-triazin-2-yl)-4-methylmorpholinium chloride and methylaminoacetaldehyde dimethyl acetal is (1-1.5) g: (120-200) mL: (0.62-0.95) g: (0.14-0.22) g, the concentration of the MES buffer is 0.1 mol / L, pH=5.5, the continuous stirring time is 15-30 min, the heating stirring temperature is 60-65℃, the heating time is 20-24 h, during the dialysis, the molecular cut-off of the dialysis bag is 14 kDa, first dialysis for 2 days with 0.1 mol / L sodium chloride solution, and then dialysis for 1 day with deionized water.

[0019] As preferred, in the Q2, the amount ratio of the intermediate and deionized water is (1-1.8) g: (100-180) mL, acid hydrolysis is carried out for 2 days with 0.2 mol / L hydrochloric acid solution, the pH is adjusted to 3.8-4.2 with 0.1 mol / L sodium bicarbonate solution, the standing time is 10-12 h, and dialysis is carried out for 2-3 days with deionized water.

[0020] As preferred, in the Q3, the heating stirring temperature is 88-92℃, the amount ratio of the polyvinyl alcohol solution, the modified sodium hyaluronate solution and the polyacrylic acid solution is (30-45) g: (2-3) g: (20-28) g, the heating reaction temperature is 110-125℃, the reaction time is 6-8 h, and the washing time is 48-52 h with distilled water.

[0021] As preferred, in the step two, the area of the water storage pool is 6 mu, the height is 6 m, the water body does not freeze when the temperature is lower than 0℃, the area of the first-stage treatment pool is 54 mu, the height is 0.6 m, the area of the second-stage treatment pool is 9 mu, the height is 0.6 m, the area of the third-stage treatment pool is 1.5 mu, the height is 0.6 m, the area of the fourth-stage treatment pool is 0.25 mu, the height is 0.6 m, and the area of the ice storage pool is 6 mu, the height is 10 m, cement columns with a spacing of 2 m and a height of 0.1 m are installed in the first-stage to fourth-stage treatment pools.

[0022] As preferred, in the step two, the ice body is removed to the ice storage pool when the thickness of the ice body is 50 cm, and the treatment order of sequentially discharging the sewage into the next-stage treatment pool is: discharging the sewage in the fourth-stage treatment pool into the sludge pool, discharging the sewage in the third-stage treatment pool into the fourth-stage treatment pool, discharging the sewage in the second-stage treatment pool into the third-stage treatment pool, and discharging the sewage in the first-stage treatment pool into the second-stage treatment pool.

[0023] In summary, due to the adoption of the above technical solutions, the present application has the following beneficial effects:

[0024] The application firstly utilizes sodium hyaluronate, methylamino acetaldehyde dimethyl acetal, polyvinyl alcohol and polyacrylic acid as raw materials to prepare a composite adsorption material, the material is green and environmentally friendly and can be reused, the composite adsorption material is applied in the pretreatment process of rural sewage, the content of microorganisms and bacteria in the rural sewage can be effectively reduced, then the pretreated rural sewage is concentrated by natural freezing, so that COD, TN and TP in the sewage are efficiently concentrated, finally the concentrated sewage is treated by the ecological floating island technology, and the ice with low pollutant concentration is collected and applied in rural landscape and agricultural irrigation, the whole process is simple in operation, low in cost and low in operation cost, and is suitable for northern rural areas. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0026] Figure 1 It is a flow chart of the method for treating rural sewage by the application of natural freezing. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] Embodiment 1: The present embodiment discloses a preparation method of a composite adsorption material, comprising the following steps:

[0029] Q1: 1.25g of sodium hyaluronate is added to 100mL of MES buffer solution with a concentration of 0.1mol / L and pH=5.5, stirred and mixed, then 0.78g of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl morpholinium chloride is added, continues to stir for 30min, then 0.18g of methylamino acetaldehyde dimethyl acetal is added, heated and stirred at 60℃ for 24h, condenses and refluxes, after the refluxing is completed, dialysis is performed, the molecular cut-off of the dialysis bag is 14kDa, first dialysis is performed for 2 days using 0.1mol / L sodium chloride solution, then dialysis is performed for 1 day using deionized water, and freeze-drying is performed to obtain an intermediate;

[0030] Q2: 1.4 g of the intermediate was added to 140 mL of deionized water, and acid hydrolysis was performed with 0.2 mol / L hydrochloric acid solution for 2 days, 0.1 mol / L sodium bicarbonate solution was used to adjust pH = 4, and the solution was left to stand for 12 h, and deionized water was used for dialysis for 3 days to obtain modified sodium hyaluronate;

[0031] Q3: 2.4 g of polyvinyl alcohol was added to 26.7 mL of deionized water, and the solution was dissolved by heating and stirring at 90°C to obtain a polyvinyl alcohol solution, 1 g of modified sodium hyaluronate was added to 100 mL of deionized water, and the solution was dissolved by stirring to obtain a modified sodium hyaluronate solution, 1.8 g of polyacrylic acid was added to 24.8 mL of deionized water, and the solution was uniformly mixed by stirring to obtain a polyacrylic acid solution, then 37.5 g of the polyvinyl alcohol solution, 2.5 g of the modified sodium hyaluronate solution and 24 g of the polyacrylic acid solution were uniformly mixed to obtain an electrospinning solution, and a nanometer membrane was obtained by electrospinning technology, and the membrane was heated and reacted at 115°C for 8 h, washed with distilled water for 48 h, and freeze-dried to obtain a composite adsorption material.

[0032] Referring to Figure 1 The embodiment provides a method for treating rural sewage by natural freezing, and the method comprises the following steps:

[0033] Step one: the collected rural sewage is flowed into a sand settling tank through a grid with a grid spacing of less than or equal to 20 mm, and is deposited for 30 min, lime or ferrous sulfate is added to adjust pH to 7, and a composite adsorption material is added for adsorption treatment for 90 min, after the adsorption treatment is completed, the composite adsorption material is removed, and pretreated rural sewage is obtained;

[0034] Step two: the pretreated rural sewage is added to a water storage tank (with an area of 6 mu, a height of 6 m, and a water body that does not freeze when the temperature is lower than 0°C), and is then sequentially flowed into a first-stage treatment tank (with an area of 54 mu and a height of 0.6 m), a second-stage treatment tank (with an area of 9 mu and a height of 0.6 m), a third-stage treatment tank (with an area of 1.5 mu and a height of 0.6 m) and a fourth-stage treatment tank (with an area of 0.25 mu and a height of 0.6 m), the fourth-stage treatment tank is connected to a sludge tank, and is frozen by natural cooling until the ice body has a thickness of 50 cm, the ice bodies in the first-stage treatment tank, the second-stage treatment tank, the third-stage treatment tank and the fourth-stage treatment tank are moved into a storage ice tank (with an area of 6 mu and a height of 10 m), and then the sewage is sequentially flowed into a next-stage treatment tank in the order of: the sewage in the fourth-stage treatment tank is flowed into the sludge tank, the sewage in the third-stage treatment tank is flowed into the fourth-stage treatment tank, the sewage in the second-stage treatment tank is flowed into the third-stage treatment tank, the sewage in the first-stage treatment tank is flowed into the second-stage treatment tank, and the operation is repeated;

[0035] Step three: after the temperature rises, the mixed sewage in the sludge tank is treated by an ecological floating island technology, and the ice in the storage ice tank is dissolved and used for rural landscape and agricultural irrigation.

[0036] Embodiment 2: The embodiment discloses a preparation method of a composite adsorption material, and comprises the following steps:

[0037] Q1: 1g of sodium hyaluronate is added into 120mL of MES buffer solution with a concentration of 0.1mol / L and pH=5.5, and then stirred and mixed, 0.62g of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride is added, and stirring is continued for 30min, then 0.14g of methylaminoacetal dimethyl ketal is added, and heating and stirring are carried out at 60℃ for 24h, and then condensation reflux is carried out, after the reflux is completed, dialysis is carried out, the molecular weight cut-off of the dialysis bag is 14kDa, first dialysis is carried out using 0.1mol / L sodium chloride solution for 2 days, then dialysis is carried out using deionized water for 1 day, and then freeze-drying is carried out, to obtain an intermediate;

[0038] Q2: 1g of the intermediate is added into 100mL of deionized water, and acid hydrolysis is carried out using 0.2mol / L hydrochloric acid solution for 2 days, 0.1mol / L sodium bicarbonate solution is used to adjust pH=4, and then standing is carried out for 12h, and then dialysis is carried out using deionized water for 3 days, to obtain modified sodium hyaluronate;

[0039] Q3: 2.4g of polyvinyl alcohol is added into 26.7mL of deionized water, and heating and stirring are carried out to dissolve the polyvinyl alcohol, to obtain a polyvinyl alcohol solution, 1g of the modified sodium hyaluronate is added into 100mL of deionized water, and stirring and dissolution are carried out, to obtain a modified sodium hyaluronate solution, 1.8g of polyacrylic acid is added into 24.8mL of deionized water, and stirring is carried out, to obtain a polyacrylic acid solution, then 30g of the polyvinyl alcohol solution, 2g of the modified sodium hyaluronate solution and 28g of the polyacrylic acid solution are uniformly mixed, to obtain an electrospinning solution, and then a nanometer membrane is obtained through an electrospinning technology, heating and reaction are carried out at 115℃ for 8h, washing is carried out using distilled water for 48h, and then freeze-drying is carried out, to obtain the composite adsorption material.

[0040] Referring to Figure 1 As shown in the figure, the embodiment provides a method for treating rural sewage by using natural icing, and the method comprises the following steps:

[0041] Step one: the collected rural sewage is flowed into a sand settling tank through a grid with a grid spacing ≤20mm, and is settled for 30min, lime or ferrous sulfate is added to adjust pH=7, and a composite adsorption material is added for adsorption treatment for 90min, after the adsorption treatment is completed, the composite adsorption material is removed, and pretreated rural sewage is obtained;

[0042] Step two: the pretreated rural sewage is added into a water storage pool (6 mu in area, 6 m in height, the water body does not freeze when the temperature is lower than 0℃), and then is sequentially discharged into a first-stage treatment pool (54 mu in area, 0.6 m in height), a second-stage treatment pool (9 mu in area, 0.6 m in height), a third-stage treatment pool (1.5 mu in area, 0.6 m in height) and a fourth-stage treatment pool (0.25 mu in area, 0.6 m in height), the fourth-stage treatment pool is connected with a sludge pool, and when the ice body is frozen to a thickness of 50 cm by using natural cooling, the ice bodies in the first-stage treatment pool, the second-stage treatment pool, the third-stage treatment pool and the fourth-stage treatment pool are moved into a ice storage pool (6 mu in area, 10 m in height), and then the sewage is sequentially discharged into a next-stage treatment pool in the order of: the sewage in the fourth-stage treatment pool is discharged into the sludge pool, the sewage in the third-stage treatment pool is discharged into the fourth-stage treatment pool, the sewage in the second-stage treatment pool is discharged into the third-stage treatment pool, and the sewage in the first-stage treatment pool is discharged into the second-stage treatment pool, and the operation is repeated;

[0043] Step three: after the temperature rises, the mixed sewage in the sludge pool is treated by using the ecological floating island technology, and the ice in the ice storage pool is used for rural landscape and agricultural irrigation water after being dissolved.

[0044] Embodiment 3: The embodiment discloses a preparation method of a composite adsorption material, comprising the following steps:

[0045] Q1: 1.5 g of sodium hyaluronate is added into 200 mL of MES buffer solution with a concentration of 0.1 mol / L and pH=5.5, and then stirred and mixed, 0.95 g of 4-(4, 6-dimethoxy-1, 3, 5-triazin-2-yl)-4-methyl morpholinium chloride is added, and stirring is continued for 30 min, then 0.22 g of methylamino acetaldehyde dimethyl acetal is added, and heating and stirring are carried out at 60℃ for 24 h, and after refluxing, dialysis is carried out, the molecular weight cut-off of the dialysis bag is 14 kDa, first, 0.1 mol / L sodium chloride solution is used for dialysis for 2 days, then deionized water is used for dialysis for 1 day, and then freeze-drying is carried out, to obtain an intermediate;

[0046] Q2: 1.8 g of the intermediate is added into 180 mL of deionized water, and acid hydrolysis is carried out by using 0.2 mol / L hydrochloric acid solution for 2 days, 0.1 mol / L sodium bicarbonate solution is used for adjusting pH to 4, and standing is carried out for 12 h, and then deionized water is used for dialysis for 3 days, to obtain modified sodium hyaluronate;

[0047] Q3: 2.4 g of polyvinyl alcohol was added to 26.7 mL of deionized water, heated and stirred to dissolve at 90°C to obtain a polyvinyl alcohol solution, 1 g of modified sodium hyaluronate was added to 100 mL of deionized water, stirred and dissolved to obtain a modified sodium hyaluronate solution, 1.8 g of polyacrylic acid was added to 24.8 mL of deionized water, stirred and mixed uniformly to obtain a polyacrylic acid solution, then 45 g of the polyvinyl alcohol solution, 3 g of the modified sodium hyaluronate solution and 20 g of the polyacrylic acid solution were uniformly mixed to obtain an electrospinning solution, and a nanometer membrane was obtained by electrospinning technology, heated and reacted at 115°C for 8 h, washed with distilled water for 48 h, and freeze-dried to obtain a composite adsorption material.

[0048] Referring to Figure 1 As shown in the method for treating rural sewage by natural freezing, the method comprises the following steps:

[0049] Step one: the collected rural sewage is flowed into a sand settling tank through a grid with a grid spacing of less than or equal to 20 mm, and is deposited for 30 min, lime or ferrous sulfate is added to adjust the pH to 7, and a composite adsorption material is added for adsorption treatment for 90 min, after the adsorption treatment is completed, the composite adsorption material is removed, and pretreated rural sewage is obtained;

[0050] Step two: the pretreated rural sewage is added to a water storage tank (with an area of 6 mu, a height of 6 m, and the water body does not freeze when the temperature is lower than 0°C), and then is sequentially discharged into a first-stage treatment tank (with an area of 54 mu, a height of 0.6 m), a second-stage treatment tank (with an area of 9 mu, a height of 0.6 m), a third-stage treatment tank (with an area of 1.5 mu, a height of 0.6 m) and a fourth-stage treatment tank (with an area of 0.25 mu, a height of 0.6 m), the fourth-stage treatment tank is connected with a sludge tank, and is frozen by natural cooling until the ice body has a thickness of 50 cm, then the ice body in the first-stage treatment tank, the second-stage treatment tank, the third-stage treatment tank and the fourth-stage treatment tank is moved into a ice storage tank (with an area of 6 mu, a height of 10 m), and then the sewage is sequentially discharged into a next-stage treatment tank in the order of: the sewage in the fourth-stage treatment tank is discharged into the sludge tank, the sewage in the third-stage treatment tank is discharged into the fourth-stage treatment tank, the sewage in the second-stage treatment tank is discharged into the third-stage treatment tank, the sewage in the first-stage treatment tank is discharged into the second-stage treatment tank, and the operation is repeated;

[0051] Step three: after the temperature rises, the mixed sewage in the sludge tank is treated by an ecological floating island technology, and the ice in the ice storage tank is used for rural landscape and agricultural irrigation after being dissolved.

[0052] Embodiment 4: The embodiment discloses a preparation method of a composite adsorption material, comprising the following steps:

[0053] Q1: 1.1 g of sodium hyaluronate is added to 140 mL of MES buffer with a concentration of 0.1 mol / L and pH = 5.5, the mixture is stirred, then 0.67 g of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride is added, stirring is continued for 30 min, then 0.16 g of methylaminoacetaldehyde dimethyl acetal is added, stirring is carried out at 60°C for 24 h, condensation is carried out under reflux, after the end of the reflux, dialysis is carried out, the molecular weight cut-off of the dialysis bag is 14 kDa, first dialysis is carried out for 2 days using 0.1 mol / L sodium chloride solution, then dialysis is carried out for 1 day using deionized water, and freeze-drying is carried out, to obtain an intermediate;

[0054] Q2: 1.2 g of the intermediate is added to 160 mL of deionized water, acid hydrolysis is carried out using 0.2 mol / L hydrochloric acid solution for 2 days, 0.1 mol / L sodium bicarbonate solution is used to adjust the pH to 4, and standing is carried out for 12 h, and dialysis is carried out using deionized water for 3 days, to obtain modified sodium hyaluronate;

[0055] Q3: 2.4 g of polyvinyl alcohol is added to 26.7 mL of deionized water, and stirring and dissolution are carried out at 90°C to obtain a polyvinyl alcohol solution, 1 g of modified sodium hyaluronate is added to 100 mL of deionized water, and stirring and dissolution are carried out to obtain a modified sodium hyaluronate solution, 1.8 g of polyacrylic acid is added to 24.8 mL of deionized water, and stirring and mixing are carried out to obtain a polyacrylic acid solution, then 32 g of the polyvinyl alcohol solution, 2.2 g of the modified sodium hyaluronate solution and 22 g of the polyacrylic acid solution are uniformly mixed to obtain an electrospinning solution, and a nanometer membrane is obtained by electrospinning technology, and the nanometer membrane is heated at 115°C for 8 h, washed with distilled water for 48 h, and freeze-dried to obtain a composite adsorption material.

[0056] Referring to Figure 1 As shown in the figure, the embodiment provides a method for treating rural sewage by natural freezing, comprising the following steps:

[0057] Step one: the collected rural sewage is flowed into a sand settling tank through a grid with a grid spacing ≤ 20 mm and is deposited for 30 min, lime or ferrous sulfate is added to adjust the pH to 7, and a composite adsorption material is added for adsorption treatment for 90 min, after the adsorption treatment is completed, the composite adsorption material is removed, and pretreated rural sewage is obtained;

[0058] Step two: the pretreated rural sewage is added into a water storage pool (6 mu in area, 6 m in height, the water body does not freeze when the temperature is lower than 0℃), and then is sequentially discharged into a first-stage treatment pool (54 mu in area, 0.6 m in height), a second-stage treatment pool (9 mu in area, 0.6 m in height), a third-stage treatment pool (1.5 mu in area, 0.6 m in height) and a fourth-stage treatment pool (0.25 mu in area, 0.6 m in height), the fourth-stage treatment pool is connected with a sludge pool, and when the ice body is frozen to a thickness of 50 cm by using natural cooling, the ice bodies in the first-stage treatment pool, the second-stage treatment pool, the third-stage treatment pool and the fourth-stage treatment pool are moved into a ice storage pool (6 mu in area, 10 m in height), and then the sewage is sequentially discharged into a next-stage treatment pool in the order of: the sewage in the fourth-stage treatment pool is discharged into the sludge pool, the sewage in the third-stage treatment pool is discharged into the fourth-stage treatment pool, the sewage in the second-stage treatment pool is discharged into the third-stage treatment pool, and the sewage in the first-stage treatment pool is discharged into the second-stage treatment pool, and the operation is repeated;

[0059] Step three: after the temperature rises, the mixed sewage in the sludge pool is treated by using the ecological floating island technology, and the ice in the ice storage pool is used for rural landscape and agricultural irrigation water after being dissolved.

[0060] Embodiment 5: The embodiment discloses a preparation method of a composite adsorption material, comprising the following steps:

[0061] Q1: 1.4 g of sodium hyaluronate is added into 180 mL of MES buffer solution with a concentration of 0.1 mol / L and pH=5.5, and then stirred and mixed, 0.83 g of 4-(4, 6-dimethoxy-1, 3, 5-triazin-2-yl)-4-methyl morpholinium chloride is added, and stirring is continued for 30 min, then 0.2 g of methylamino acetaldehyde dimethyl acetal is added, and heating and stirring are carried out at 60℃ for 24 h, and after refluxing, dialysis is carried out, the molecular weight cut-off of the dialysis bag is 14 kDa, first, 0.1 mol / L sodium chloride solution is used for dialysis for 2 days, then deionized water is used for dialysis for 1 day, and then freeze-drying is carried out, to obtain an intermediate;

[0062] Q2: 1.6 g of the intermediate is added into 120 mL of deionized water, and acid hydrolysis is carried out by using 0.2 mol / L hydrochloric acid solution for 2 days, 0.1 mol / L sodium bicarbonate solution is used for adjusting pH to 4, and standing is carried out for 12 h, and then deionized water is used for dialysis for 3 days, to obtain modified sodium hyaluronate;

[0063] Q3: 2.4 g of polyvinyl alcohol was added to 26.7 mL of deionized water, heated and stirred at 90°C to dissolve to obtain a polyvinyl alcohol solution, 1 g of modified sodium hyaluronate was added to 100 mL of deionized water, stirred and dissolved to obtain a modified sodium hyaluronate solution, 1.8 g of polyacrylic acid was added to 24.8 mL of deionized water, stirred and mixed uniformly to obtain a polyacrylic acid solution, then 42 g of the polyvinyl alcohol solution, 2.8 g of the modified sodium hyaluronate solution and 26 g of the polyacrylic acid solution were uniformly mixed to obtain an electrospinning solution, and a nanometer membrane was obtained by electrospinning technology, heated and reacted at 115°C for 8 h, washed with distilled water for 48 h, freeze-dried to obtain a composite adsorption material.

[0064] Referring to Figure 1 As shown in the embodiment, a method for treating rural sewage by natural freezing is provided, which comprises the following steps:

[0065] Step one: the collected rural sewage is flowed into a sand settling tank through a grid with a grid spacing ≤ 20 mm, and is deposited for 30 min, lime or ferrous sulfate is added to adjust pH = 7, and a composite adsorption material is added for adsorption treatment for 90 min, after the adsorption treatment is completed, the composite adsorption material is removed, and pretreated rural sewage is obtained;

[0066] Step two: the pretreated rural sewage is added to a water storage tank (area of 6 mu, height of 6 m, the water body does not freeze when the temperature of the water storage tank is lower than 0°C), and then is sequentially discharged into a first-stage treatment tank (area of 54 mu, height of 0.6 m), a second-stage treatment tank (area of 9 mu, height of 0.6 m), a third-stage treatment tank (area of 1.5 mu, height of 0.6 m) and a fourth-stage treatment tank (area of 0.25 mu, height of 0.6 m), the fourth-stage treatment tank is connected with a sludge tank, and is frozen by natural cooling until the ice body has a thickness of 50 cm, then the ice body in the first-stage treatment tank, the second-stage treatment tank, the third-stage treatment tank and the fourth-stage treatment tank is moved into a ice storage tank (area of 6 mu, height of 10 m), and then the sewage is sequentially discharged into a next-stage treatment tank in sequence, and the treatment sequence is: the sewage in the fourth-stage treatment tank is discharged into the sludge tank, the sewage in the third-stage treatment tank is discharged into the fourth-stage treatment tank, the sewage in the second-stage treatment tank is discharged into the third-stage treatment tank, the sewage in the first-stage treatment tank is discharged into the second-stage treatment tank, and the operation is repeated;

[0067] Step three: after the temperature rises, the mixed sewage in the sludge tank is treated by an ecological floating island technology, and the ice in the ice storage tank is used for rural landscape and agricultural irrigation after being dissolved.

[0068] According to the climate conditions in Inner Mongolia, the rural sewage is treated by the method of Example 1, the test time is from November 1 to April 1 of the next year, and the COD, TN and TP in the water storage tank, the first-stage treatment tank, the second-stage treatment tank, the third-stage treatment tank, the fourth-stage treatment tank and the ice storage tank are detected, and the test results are shown in Table 1.

[0069] Table 1 Concentration and reduction rate of COD, TN and TP in the storage pool and ice storage pool

[0070]

[0071] Table 2 Total amount and concentration of pollutants in ice in each treatment pool during 11.1 to 1.15 of next year

[0072]

[0073] Table 3 Total amount and concentration of pollutants in water in each treatment pool during 11.1 to 1.15 of next year

[0074]

[0075] Table 4 Total amount and concentration of pollutants in ice in each treatment pool during 1.15 to 4.1

[0076]

[0077] Table 5 Total amount and concentration of pollutants in water in each treatment pool during 1.15 to 4.1

[0078]

[0079] From the data in Tables 1-5, it can be seen that the use of natural freezing method to treat rural sewage can simply and effectively remove COD, TN and TP in the sewage. Tables 2-5 show the total amount of COD, TN and TP before treatment in different treatment pools and the concentration of COD, TN and TP after treatment in different treatment pools during 11.1 to 1.15 of next year and 1.15 to 4.1. From the data in Tables 1-5, it can be found that the content of COD, TN and TP in water and ice is decreased after treatment, which indicates that the treatment method can effectively remove pollutants in rural sewage and is easy to operate and promote.

[0080] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent substitutions or changes to the technical solutions and inventive concept of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

[0081] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to provide the best illustration of the application and its practical application to those skilled in the art and to enable those skilled in the art to utilize the application in its best mode. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A method for treating rural sewage by means of natural freezing, characterized in that, The method comprises the following steps: Step one: the collected rural sewage is treated by a grid, flows into a grit chamber for sedimentation, pH is adjusted, a composite adsorption material is added for adsorption treatment, the composite adsorption material is removed after the adsorption treatment, and pretreated rural sewage is obtained; Step two: the pretreated rural sewage is added into a water storage tank, and then is sequentially discharged into a first-stage treatment tank, a second-stage treatment tank, a third-stage treatment tank and a fourth-stage treatment tank, the fourth-stage treatment tank is connected with a sludge tank, ice bodies in the first-stage treatment tank, the second-stage treatment tank, the third-stage treatment tank and the fourth-stage treatment tank are moved into an ice storage tank by using natural cooling and freezing, then the sewage is sequentially discharged into a next-stage treatment tank, and the operation is repeated; Step three: after the temperature rises, the mixed sewage in the sludge tank is treated by using an ecological floating island technology, and the ice in the ice storage tank is dissolved and used for rural landscape and agricultural irrigation water; In the step one, the preparation method of the composite adsorption material comprises the following steps: Q1: sodium hyaluronate is added into MES buffer solution, stirred and mixed, then 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride is added, continues to be stirred, then methylamino acetaldoxime dimethyl acetal is added, heated and stirred, condensation reflux is carried out, after the reflux is completed, dialysis is carried out, freeze-drying is carried out, and an intermediate is obtained; Q2: the intermediate is added into deionized water, acid hydrolysis is carried out, pH is adjusted, standing is carried out, dialysis is carried out, and modified sodium hyaluronate is obtained; Q3: polyvinyl alcohol is added into deionized water, heated and stirred to dissolve, so that a polyvinyl alcohol solution is obtained, the modified sodium hyaluronate is added into deionized water, stirred and dissolved to obtain a modified sodium hyaluronate solution, then the polyvinyl alcohol solution, the modified sodium hyaluronate solution and a polyacrylic acid solution are uniformly mixed to obtain an electrostatic spinning solution, a nanometer membrane is obtained by using an electrostatic spinning technology, heating reaction is carried out, washing is carried out, freeze-drying is carried out, and the composite adsorption material is obtained.

2. The method of treating rural sewage by means of natural freezing according to claim 1, characterized in that, In the step one, the grid distance of the grid is ≤20 mm, the sedimentation time is ≥30 min, lime or ferrous sulfate is added to adjust pH to 6-8, and the adsorption treatment time is 60-90 min.

3. The method of treating rural sewage by means of natural freezing according to claim 1, characterized in that, In the Q1, the amount ratio of sodium hyaluronate, MES buffer solution, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride and methylamino acetaldoxime dimethyl acetal is (1-1.5) g:(120-200) mL:(0.62-0.95) g:(0.14-0.22) g, the concentration of the MES buffer solution is 0.1 mol / L, pH is 5.5, the continued stirring time is 15-30 min, the heating and stirring temperature is 60-65 DEG C, the heating time is 20-24 h, in the dialysis process, the molecular cut-off of the dialysis bag is 14 kDa, first, 0.1 mol / L sodium chloride solution is used for dialysis for 2 days, and then deionized water is used for dialysis for 1 day.

4. The method of treating rural sewage by means of natural freezing according to claim 1, characterized in that, The Q2, the intermediate and deionized water are used in a ratio of (1-1.8) g:(100-180) mL, acid hydrolysis is carried out using 0.2 mol / L hydrochloric acid solution for 2 days, 0.1 mol / L sodium bicarbonate solution is used to adjust pH=3.8-4.2, the standing time is 10-12 h, and deionized water is used for dialysis for 2-3 days.

5. The method of treating rural sewage by means of natural freezing according to claim 1, characterized in that, In the Q3, the heating and stirring temperature is 88-92℃, the polyvinyl alcohol solution, the modified sodium hyaluronate solution and the polyacrylic acid solution are used in a ratio of (30-45) g:(2-3) g:(20-28) g, the heating reaction temperature is 110-125℃, and the reaction time is 6-8 h, and the washing is carried out using distilled water for 48-52 h.

6. The method of treating rural sewage by means of natural freezing according to claim 1, characterized in that, In the second step, the water storage pool has an area of 6 mu and a height of 6 m, the water body does not freeze when the temperature is lower than 0℃, the first-stage treatment pool has an area of 54 mu and a height of 0.6 m, the second-stage treatment pool has an area of 9 mu and a height of 0.6 m, the third-stage treatment pool has an area of 1.5 mu and a height of 0.6 m, the fourth-stage treatment pool has an area of 0.25 mu and a height of 0.6 m, and the ice storage pool has an area of 6 mu and a height of 10 m, cement columns with an interval of 2 m and a height of 0.1 m are installed in the first-stage to fourth-stage treatment pools.

7. The method of treating rural sewage by means of natural freezing according to claim 1, characterized in that, In the second step, the ice body is removed to the ice storage pool when the thickness of the ice body is 50 cm, and the sewage is sequentially discharged into the next-stage treatment pool in the following order: the sewage in the fourth-stage treatment pool is discharged into the sludge pool, the sewage in the third-stage treatment pool is discharged into the fourth-stage treatment pool, the sewage in the second-stage treatment pool is discharged into the third-stage treatment pool, and the sewage in the first-stage treatment pool is discharged into the second-stage treatment pool.

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