Phosphorus and nitrogen removal composite filler, preparation method thereof and application thereof in water treatment

Abstract

The application discloses a phosphorus and nitrogen removal composite filler and a preparation method and application thereof in water treatment. The preparation method comprises the following steps: adding polyvinyl alcohol and sodium alginate into water, heating and dissolving to obtain a hydrogel; adding polycaprolactone, corncob powder and zero-valent iron powder into the hydrogel, uniformly stirring to obtain a mixed solution; adding aerobic denitrifying bacteria P.furukawaii ZS1 liquid into the mixed solution, uniformly stirring, and freezing and forming; taking out the filler after freezing and forming, placing the filler into a chemical cross-linking reagent solution, carrying out cross-linking reaction, and washing to obtain the phosphorus and nitrogen removal composite filler. The method combines the agricultural waste corncob, the zero-valent iron powder and the aerobic denitrifying bacteria, has low filler manufacturing cost, low equipment investment and operation cost, and can successfully achieve the purpose of efficiently purifying aquaculture tail water at normal temperature and low temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tail water treatment, and particularly relates to a phosphorus and nitrogen removal composite filler, a preparation method thereof and application thereof in water treatment. BACKGROUND

[0002] In recent years, the global aquaculture scale has increased significantly, and has greatly changed the pattern of global food consumption. As the amount of fish caught in the natural environment has reached the limit, the public has begun to rely on aquaculture aquatic products to maintain protein sources. The feed put in the process of aquaculture contains a large amount of nitrogen and phosphorus, but only about 25% of the nitrogen and phosphorus can be converted into fish biomass, and the remaining nutrients and fish manure are discharged into the surrounding water with the aquaculture tail water, causing serious harm to the surrounding water ecosystem.

[0003] The traditional biological denitrification process includes two key steps of aerobic autonitification and anaerobic heterotrophic denitrification (Hao, Z.-L., Ali, A., Ren, Y., Su, J.-F. and Wang, Z. (2022) A mechanistic review on aerobic denitrification for nitrogen removal in water treatment. Science of the Total Environment 847, 157452.). Considering that the dissolved oxygen in the aquaculture system often needs to be maintained at more than 5 mg / L, the traditional anaerobic denitrification process is inhibited, and the use of aerobic denitrification bacteria that can achieve simultaneous nitrification and denitrification under aerobic conditions is expected to achieve a key breakthrough in the denitrification technology of aquaculture tail water. However, the aquaculture tail water with low carbon-nitrogen ratio often needs to be treated at low temperature, and the denitrification and phosphorus removal efficiency is very low, which puts higher requirements on the application of aerobic denitrification bacteria in the process of aquaculture tail water treatment.

[0004] On the other hand, external carbon source is an effective method to improve the denitrification efficiency of aquaculture tail water, however, traditional liquid carbon sources (methanol, ethanol, acetic acid, etc.). However, adding dissolved carbon sources in natural water bodies will increase the organic pollution load, and if the calculated amount is unreasonable, it may even cause secondary pollution. Therefore, in recent years, solid carbon sources (corn cob, rice husk, polylactide, etc.) have been widely used in aquaculture tail water treatment due to their appropriate carbon release rate, long carbon release time, which can provide favorable conditions for microbial biofilm formation, easy management and long-term operation, etc. However, most of the researches on the application of solid carbon sources in recirculating aquaculture systems still cannot effectively remove phosphorus in aquaculture tail water.

[0005] In order to achieve efficient phosphorus removal of wastewater, iron-based materials have been widely studied in the removal of phosphate in wastewater. Compared with biological phosphorus removal, the Fe(II) and Fe(III) generated by the oxidation of externally added iron-containing materials (nano-iron, sponge iron, zero-valent iron, etc.) can achieve efficient phosphorus removal through precipitation. In a biological filter added with nano zero-valent iron, the phosphorus removal efficiency can reach 100%, and is basically not affected by temperature.

[0006] Currently, there is a need for a method of organically combining aerobic denitrifying bacteria, solid carbon source and iron-based material to make a aquaculture tail water efficient denitrification and phosphorus removal filler to solve the problem of difficult denitrification and phosphorus removal of aquaculture tail water at low temperature. SUMMARY

[0007] In order to overcome the shortcomings of the prior art, the present application provides a aquaculture tail water efficient phosphorus removal and denitrification composite filler organically combining aerobic denitrifying bacteria, solid carbon source and iron-based material, and a preparation method thereof and application in water treatment. The composite filler of the present application has low manufacturing cost, low equipment investment and operation cost, and the manufactured phosphorus removal and denitrification composite filler can successfully achieve the purpose of efficient purification of aquaculture tail water at low temperature, and can be used as a biological membrane carrier in the process of low-temperature aquaculture tail water treatment, and is easy to popularize and use.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application to solve its technical problems is:

[0009] A preparation method of a phosphorus removal and denitrification composite filler, comprising the following steps:

[0010] (1) adding polyvinyl alcohol and sodium alginate into water, heating and dissolving to obtain a hydrogel;

[0011] (2) adding polycaprolactone, corn cob powder and zero-valent iron powder into the hydrogel of step (1) and stirring uniformly to obtain a mixed solution;

[0012] (3) adding aerobic denitrifying bacteria P.furukawaii ZS1 (preserved unit: Guangdong Microbial Culture Collection Center; preservation time: March 2018; preservation number: GDMCC 1.2405) bacterial solution into the mixed solution of step (2) and stirring uniformly, and freezing into shape;

[0013] (4) taking out the filler after freezing into shape in step (3) and placing it into a chemical crosslinking reagent solution, crosslinking reaction, washing to obtain a phosphorus removal and denitrification composite filler.

[0014] Preferably, the mass ratio of polyvinyl alcohol and sodium alginate in step (1) is 5-10:1; the volume to mass ratio of water and polyvinyl alcohol is 1L:50-150g;

[0015] Further preferably, the mass ratio of the polyvinyl alcohol and sodium alginate in step (1) is 8:1; the volume-mass ratio of the water and polyvinyl alcohol is 1L:80g.

[0016] Preferably, the temperature for heating and dissolving in step (1) is 80-100℃; the time is 1-5 hours.

[0017] Further preferably, the temperature for heating and dissolving in step (1) is 95℃; the time is 2 hours.

[0018] Preferably, the corncob powder in step (2) is obtained by crushing corncob; the crushed corncob is sieved through a 50-200 mesh sieve.

[0019] Further preferably, the crushed corncob is sieved through a 100 mesh sieve.

[0020] Preferably, the particle size of the corncob powder in step (2) is 75-147μm.

[0021] Preferably, the mass ratio of the polycaprolactone, corncob powder and zero-valent iron powder in step (2) is 55:20-60:0-60.

[0022] Further preferably, the mass ratio of the polycaprolactone, corncob powder and zero-valent iron powder in step (2) is 55:40:0-60 (0, 20, 40, 60, etc.).

[0023] Preferably, the volume-mass ratio of the water in step (1) and the corncob powder in step (2) is 1L:20-80g.

[0024] Further preferably, the volume-mass ratio of the water in step (1) and the corncob powder in step (2) is 1L:40g.

[0025] Preferably, the OD600 of the aerobic denitrifying bacteria P. furukawaii ZS1 bacterial solution in step (3) is 0.5-15.

[0026] Further preferably, the OD600 of the aerobic denitrifying bacteria P. furukawaii ZS1 bacterial solution in step (3) is 1.00±0.05.

[0027] Preferably, the volume ratio of the aerobic denitrifying bacteria P. furukawaii ZS1 bacterial solution and the mixed solution in step (3) is 1-5:10.

[0028] Further preferably, the volume ratio of the aerobic denitrifying bacteria P. furukawaii ZS1 bacterial solution and the mixed solution in step (3) is 3-10.

[0029] Preferably, the aerobic denitrifying bacteria P.furukawaii ZS1 liquid in step (3) is obtained by culturing in Luria-Bertani medium;

[0030] Preferably, the temperature of the freeze forming in step (3) is -30 to -10 DEG C, and the time is 12 to 36 hours.

[0031] Further preferably, the temperature of the freeze forming in step (3) is -20 DEG C, and the time is 24 hours.

[0032] Preferably, the chemical cross-linking reagent solution in step (4) is a boric acid solution containing 2 to 6% CaCl2.

[0033] Further preferably, the chemical cross-linking reagent solution in step (4) is a saturated boric acid solution containing 4% CaCl2.

[0034] Preferably, the temperature of the cross-linking reaction in step (4) is 0 to 10 DEG C, and the time is 8 to 16 hours.

[0035] Further preferably, the temperature of the cross-linking reaction in step (4) is 4 DEG C, and the time is 12 hours.

[0036] The phosphorus and nitrogen removal composite filler prepared by the preparation method.

[0037] The application of the phosphorus and nitrogen removal composite filler in water treatment.

[0038] Preferably, the water treated is aquaculture tail water; the temperature of the water treatment is 10 to 30 DEG C (10 DEG C, 15 DEG C, 20 DEG C, 25 DEG C, 30 DEG C, etc.); and the water treatment is inoculated with aerobic tank activated sludge.

[0039] Further preferably, the temperature of the water treatment is 14 DEG C ± 0.5 DEG C.

[0040] Further preferably, the oxygen concentration of the aquaculture tail water is 5 to 7 mg / L; and the inoculation amount of the aerobic tank activated sludge is 1 to 3 g / L.

[0041] More preferably, the inoculation amount of the aerobic tank activated sludge is 2 g / L.

[0042] The beneficial effects of the present application are:

[0043] (1) The present application uses zero-valent iron powder and solid carbon source to fix aerobic denitrifying bacteria, so that the efficient nitrogen and phosphorus removal filler simultaneously serves as an electron donor and a biofilm carrier, which can meet the optimal carbon-nitrogen ratio requirement of the aerobic denitrifying bacteria, provide trace elements required for the growth of the bacteria, reduce the influence of water flow scouring and environmental temperature reduction on the functional microorganisms, and enable the functional microorganisms to normally exert their physiological and biochemical properties at low temperature.

[0044] (2) The preparation process of the present application is simple, does not need high-temperature calcination, has low equipment investment cost and operation cost, and fully utilizes agricultural waste corn cobs, which is conducive to achieving the goal of "waste treatment with waste" and meets the concept of sustainable development. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 Scanning electron microscope (SEM) test graphs of the three kinds of aquaculture tail water high-efficiency denitrification and phosphorus removal fillers prepared by the present application examples 1, 2 and 4 before and after use. DETAILED DESCRIPTION

[0046] The present application will be further described below in combination with the drawings of the specification and specific preferred embodiments, but the protection scope of the present application is not limited thereby.

[0047] A preparation method of an aquaculture tail water phosphorus removal and denitrification composite filler, comprising the following steps:

[0048] (1) Corn cobs are crushed through a 100-mesh sieve to obtain particles with a particle size of 75-147 μm (corn cob powder);

[0049] (2) Prepare hydrogel: add 80 g of polyvinyl alcohol and 10 g of sodium alginate per liter of water; after mixing uniformly, heat in a water bath at 95℃ for 2 hours until completely dissolved;

[0050] (3) Put the following components in the hydrogel mixture according to the weight ratio: based on the water in step (2), add 55 g of polycaprolactone, 40 g of corn cob powder and 0-60 g of zero-valent iron powder per liter of water, and stir uniformly;

[0051] (4) After cooling to room temperature, add 0-300 ml of Luria-Bertani culture medium (containing 5 g of yeast extract, 10 g of peptone and 10 g of sodium chloride per liter) to the OD600 = 1.00±0.05 aerobic denitrifying bacteria P.furukawaii ZS1 (GenBank No.MK615112) liquid to the mixture (1L) in step (3), and stir uniformly;

[0052] (5) Pour the mixture into a 1cm×1cm×1cm square mold, freeze at -20℃ for 24 hours to form;

[0053] (6) Chemical reagent crosslinking: take out the frozen filler from the mold, immediately put it into the prepared saturated boric acid solution containing 4% CaCl2, crosslink at 4℃ for 12 hours, and then wash the surface crosslinking agent with water to complete the preparation of the filler.

[0054] Example 1

[0055] A preparation method of an aquaculture tail water phosphorus removal and denitrification composite filler, comprising the following steps:

[0056] (1) Corn cob was crushed to pass through a 100-mesh sieve to obtain particles with a particle size of 75-147 μm;

[0057] (2) Preparation of hydrogel: 80 g of polyvinyl alcohol and 10 g of sodium alginate were added per liter of water; after uniform mixing, heating in a water bath at 95°C for 2 hours until complete dissolution;

[0058] (3) The following components were taken by weight ratio and placed in the hydrogel mixture: 55 g of polycaprolactone, 40 g of corn cob powder, and 0 g of zero-valent iron powder per liter of water based on the water of step (2), and stirred uniformly;

[0059] (4) After cooling to room temperature, 0 ml of aerobic denitrifying bacteria P. furukawaii ZS1 (GenBank No. MK615112) bacterial solution cultured in Luria-Bertani medium to OD600 = 1.00 ± 0.05 was added to the mixture (1 L) of step (3) and stirred uniformly;

[0060] (5) The mixture was poured into a 1 cm x 1 cm x 1 cm square mold and frozen at -20°C for 24 hours to form a shape;

[0061] (6) Chemical reagent crosslinking: the frozen filler was removed from the mold and immediately placed in a prepared saturated boric acid solution containing 4% CaCl2 at 4°C for 12 hours of crosslinking. After washing the surface crosslinking agent with water, the filler preparation was completed.

[0062] Example 2

[0063] A method for preparing a composite filler for phosphorus and nitrogen removal from aquaculture tail water, comprising the following steps:

[0064] (1) Corn cob was crushed to pass through a 100-mesh sieve to obtain particles with a particle size of 75-147 μm;

[0065] (2) Preparation of hydrogel: 80 g of polyvinyl alcohol and 10 g of sodium alginate were added per liter of water; after uniform mixing, heating in a water bath at 95°C for 2 hours until complete dissolution;

[0066] (3) The following components were taken by weight ratio and placed in the hydrogel mixture: 55 g of polycaprolactone, 40 g of corn cob powder, and 0 g of zero-valent iron powder per liter of water based on the water of step (2), and stirred uniformly;

[0067] (4) After cooling to room temperature, 300 ml of aerobic denitrifying bacteria P. furukawaii ZS1 (GenBank No. MK615112) bacterial solution cultured in Luria-Bertani medium to OD600 = 1.00 ± 0.05 was added to the mixture (1 L) of step (3) and stirred uniformly;

[0068] (5) Pour the mixed solution into a 1cm x 1cm x 1cm square mold, freeze at -20℃ for 24 hours to shape;

[0069] (6) Chemical reagent crosslinking: take out the frozen filler from the mold, immediately put it into the prepared saturated boric acid solution containing 4% CaCl2, crosslink at 4℃ for 12 hours, and then wash the surface crosslinking agent with water to complete the preparation of the filler.

[0070] Example 3

[0071] A method for preparing a phosphorus and nitrogen removal composite filler for aquaculture tail water, comprising the following steps:

[0072] (1) Corn cob is crushed to pass through a 100 mesh sieve to obtain particles with a particle size of 75-147μm;

[0073] (2) Prepare a hydrogel: add 80g of polyvinyl alcohol and 10g of sodium alginate per liter of water; mix well and heat in a water bath at 95℃ for 2 hours until completely dissolved;

[0074] (3) Put the following components in the hydrogel mixture according to the weight ratio: add 55g of polycaprolactone, 40g of corn cob powder, and 20g of zero-valent iron powder per liter of water based on the water of step (2), and stir well;

[0075] (4) After cooling to room temperature, add 300ml of P. furukawaii ZS1 (GenBank No. MK615112) bacterial solution cultured in Luria-Bertani medium to OD600 = 1.00±0.05 to the mixture (1L) of step (3), and stir well;

[0076] (5) Pour the mixed solution into a 1cm x 1cm x 1cm square mold, freeze at -20℃ for 24 hours to shape;

[0077] (6) Chemical reagent crosslinking: take out the frozen filler from the mold, immediately put it into the prepared saturated boric acid solution containing 4% CaCl2, crosslink at 4℃ for 12 hours, and then wash the surface crosslinking agent with water to complete the preparation of the filler.

[0078] Example 4

[0079] A method for preparing a phosphorus and nitrogen removal composite filler for aquaculture tail water, comprising the following steps:

[0080] (1) Corn cob is crushed to pass through a 100 mesh sieve to obtain particles with a particle size of 75-147μm;

[0081] (2) Prepare a hydrogel: add 80g of polyvinyl alcohol and 10g of sodium alginate per liter of water; mix well and heat in a water bath at 95℃ for 2 hours until completely dissolved;

[0082] (3) Put the following components into the hydrogel mixture by weight ratio: 55 g of polycaprolactone, 40 g of corn cob powder, and 40 g of zero-valent iron powder per liter of water based on the water in step (2), and stir uniformly;

[0083] (4) After cooling to room temperature, add 300 ml of aerobic denitrifying bacteria P. furukawaii ZS1 (GenBank No. MK615112) bacterial solution cultured in Luria-Bertani medium to OD600 = 1.00 ± 0.05 to the mixture (1L) in step (3), and stir uniformly;

[0084] (5) Pour the mixture into a 1cm x 1cm x 1cm square mold and freeze at -20°C for 24 hours to shape;

[0085] (6) Chemical reagent crosslinking: remove the frozen filler from the mold and immediately place it in a prepared saturated boric acid solution containing 4% CaCl2, crosslink at 4°C for 12 hours, and then wash the surface crosslinking agent with water to complete the preparation of the filler.

[0086] Example 5

[0087] A method for preparing a phosphorus and nitrogen removal composite filler for aquaculture tail water, comprising the following steps:

[0088] (1) Corn cob is crushed to pass through a 100 mesh sieve to obtain particles with a particle size of 75-147 μm;

[0089] (2) Prepare a hydrogel: add 80 g of polyvinyl alcohol and 10 g of sodium alginate per liter of water; mix uniformly and heat in a water bath at 95°C for 2 hours until completely dissolved;

[0090] (3) Put the following components into the hydrogel mixture by weight ratio: 55 g of polycaprolactone, 40 g of corn cob powder, and 40 g of zero-valent iron powder per liter of water based on the water in step (2), and stir uniformly;

[0091] (4) After cooling to room temperature, add 300 ml of aerobic denitrifying bacteria P. furukawaii ZS1 (GenBank No. MK615112) bacterial solution cultured in Luria-Bertani medium to OD600 = 1.00 ± 0.05 to the mixture (1L) in step (3), and stir uniformly;

[0092] (5) Pour the mixture into a 1cm x 1cm x 1cm square mold and freeze at -20°C for 24 hours to shape;

[0093] (6) Chemical reagent cross-linking: The frozen filler was taken out of the mold and immediately placed in a prepared saturated boric acid solution containing 4% CaCl2, cross-linked at 4°C for 12 hours, and then washed with water to remove the surface cross-linking agent. The filler was prepared.

[0094] Application Example 1

[0095] Effect of different zero-valent iron content on phosphorus and nitrogen removal in aquaculture tail water by composite filler:

[0096] Four parallel shake flasks were established, and the four fillers in Examples 2, 3, 4, and 5 were filled into the four reactors, respectively. Each shake flask contained 250 mL of synthetic aquaculture tail water and 20 g of filler. The shake flasks were placed in a shaker at a speed of 150 r / min for 24 hours. In all the shake flasks, 2 g / L of MLSS of activated sludge from an aerobic tank (Li'ankeng Sewage Treatment Plant in Guangzhou, China) was inoculated. The main components of the synthetic aquaculture tail water were 5 mg / L of ammonia nitrogen, 10 mg / L of nitrate nitrogen, and 3 mg / L of orthophosphate. Sodium acetate was used to adjust the carbon-nitrogen ratio to 4. The temperature of the reactor was adjusted to 25±0.5°C. After 24 hours of reaction, the concentrations of total nitrogen (TN) and total phosphorus (TP) in the effluent of the reactor were detected by using the national standard detection method.

[0097] The results showed that the nitrogen removal efficiency of the fillers prepared in Examples 2, 3, 4, and 5 in aquaculture tail water was 90.17%, 92.34%, 96.23%, and 97.01%, respectively, and the phosphorus removal efficiency was 3.02%, 50.89%, 99.21, and 99.23%, respectively. Considering the preparation cost of the filler, the filler in Example 4 was selected as the filler for the subsequent test.

[0098] Application Example 2

[0099] Changes in structure and composition of a composite filler for phosphorus and nitrogen removal in aquaculture tail water before and after treatment of low-temperature aquaculture tail water:

[0100] Three parallel laboratory-scale organic glass sequencing batch biofilm reactors were established, each with an effective volume of 10 liters. The three reactors were filled with the fillers in Examples 1, 2, and 4, respectively. The filling rate of the composite material was 15%. The hydraulic retention time of the reactor was 12 hours. The reactor was operated for 55 days, and during the operation of the three reactors, the dissolved oxygen concentration in the reactor was maintained at 5-7 mg / L. In all the reactors, 2 g / L of MLSS of activated sludge from an aerobic tank (Li'ankeng Sewage Treatment Plant in Guangzhou, China) was inoculated. The main components of the synthetic aquaculture tail water were 5 mg / L of ammonia nitrogen, 10 mg / L of nitrate nitrogen, and 3 mg / L of orthophosphate. Sodium acetate was used to adjust the carbon-nitrogen ratio to 4. The temperature of the reactor was adjusted to 25±0.5°C for the first 10 days of operation and to 14±0.5°C for the last 45 days.

[0101] The composite filler used in this specific embodiment was tested using scanning electron microscopy-X-ray energy dispersive spectroscopy (SEM-EDS) before and after use. The results are as follows: Figure 1 As shown, (a) is a SEM image of the packing material before use in Example 1, (b) is a SEM image of the packing material after use in Example 1, (c) is a SEM image of the packing material before use in Example 2, (d) is a SEM image of the packing material after use in Example 2, (e) is a SEM image of the packing material before use in Example 4, and (f) is a SEM image of the packing material after use in Example 4. Figure 1 It can be concluded that the fillers prepared in the three examples had smooth surfaces before use, which effectively protected the internal materials from excessive exposure to the external environment; however, after use, obvious voids appeared on the surface of the fillers, indicating that the carbon source had been released into the water. In addition, the thickness of oxidation products in some areas of the filler surface prepared in Example 4 increased significantly, indicating that zero-valent iron powder participated in the phosphate removal process.

[0102] X-ray energy dispersive spectroscopy (EDS) was used to show the elemental composition of the fillers prepared in the three examples before and after use. As shown in Table 1, the elemental composition of the fillers prepared in each example was similar before use, with the filler prepared in Example 4 containing a small amount of zero-valent iron on its surface. After use, the zero-valent iron in the filler prepared in Example 4 was gradually exposed, and corrosion products were deposited on the surface. Element O and P were mainly distributed on the surface of the filler prepared in Example 4, indicating that phosphate adsorption and precipitation occurred on the surface of the filler prepared in Example 4.

[0103] Table 1

[0104] X-ray energy dispersive spectroscopy elemental analysis of aquaculture wastewater before and after treatment with composite packing material for nitrogen and phosphorus removal at low temperatures.

[0105]

[0106] Application Example 3

[0107] A composite packing material for phosphorus and nitrogen removal in aquaculture wastewater treatment at low temperatures achieves the following nitrogen and phosphorus removal efficiency:

[0108] A lab-scale sequencing batch biofilm reactor was established. The effective volume of the reactor was 10 L. The reactor was filled with the packing material described in Example 1. The packing rate of the composite material was 15%. The hydraulic retention time of the reactor was 12 hours. The reactor was operated for 55 days. The dissolved oxygen concentration in the reactor was maintained at 5-7 mg / L during the three reactor runs. The activated sludge with 2 g / L MLSS from the aerobic tank (LiKeng WWTP, Guangzhou, China) was inoculated in all reactors. The main components of the synthetic aquaculture effluent were 5 mg / L ammonia nitrogen, 10 mg / L nitrate nitrogen and 3 mg / L orthophosphate. The carbon-nitrogen ratio was adjusted to 4 using sodium acetate. The temperature was adjusted to 25±0.5°C for the first 10 days and to 14±0.5°C for the last 45 days. The concentrations of total nitrogen (TN) and total phosphorus (TP) in the effluent from the reactor were determined every two days using the national standard detection method.

[0109] The results show that the packing material prepared in Example 1 has a denitrification efficiency of 81.32% and a phosphorus removal efficiency of 5.18% in aquaculture effluent at room temperature (25±0.5°C); the denitrification efficiency is 54.77% and the phosphorus removal efficiency is 3.98% in aquaculture effluent at low temperature.

[0110] Application Example 4

[0111] The denitrification and phosphorus removal efficiencies of the aquaculture effluent phosphorus and nitrogen removal composite packing material in low-temperature aquaculture effluent:

[0112] A lab-scale sequencing batch biofilm reactor was established. The effective volume of the reactor was 10 L. The reactor was filled with the packing material described in Example 2. The packing rate of the composite material was 15%. The hydraulic retention time of the reactor was 12 hours. The reactor was operated for 55 days. The dissolved oxygen concentration in the reactor was maintained at 5-7 mg / L during the three reactor runs. The activated sludge with 2 g / L MLSS from the aerobic tank (LiKeng WWTP, Guangzhou, China) was inoculated in all reactors. The main components of the synthetic aquaculture effluent were 5 mg / L ammonia nitrogen, 10 mg / L nitrate nitrogen and 3 mg / L orthophosphate. The carbon-nitrogen ratio was adjusted to 4 using sodium acetate. The temperature was adjusted to 25±0.5°C for the first 10 days and to 14±0.5°C for the last 45 days. The concentrations of total nitrogen (TN) and total phosphorus (TP) in the effluent from the reactor were determined every two days using the national standard detection method.

[0113] The results show that the packing material prepared in Example 2 has a denitrification efficiency of 88.74% and a phosphorus removal efficiency of 8.82% in aquaculture effluent at room temperature (25±0.5°C); the denitrification efficiency is 76.02% and the phosphorus removal efficiency is 5.84% in aquaculture effluent at low temperature.

[0114] Application Example 5

[0115] The application discloses a kind of aquaculture tail water phosphorus removal denitrification composite filler treatment low temperature aquaculture tail water denitrification phosphorus removal efficiency:

[0116] A laboratory scale plexiglass sequencing batch biofilm reactor is established, and the effective volume of the reactor is 10 liters. The reactor is filled with the filler described in Example 4. The filling rate of the composite material is 15%. The hydraulic retention time of the reactor is 12 hours. The reactor is operated for 55 days, and the dissolved oxygen concentration in the reactor is maintained at 5-7 mg / L during the three reactor operation periods. The activated sludge in the aerobic tank (Li'ankeng Sewage Treatment Plant in Guangzhou, China) is inoculated in all reactors, and the MLSS is 2 g / L. The main components of the synthetic aquaculture tail water are 5 mg / L of ammonia nitrogen, 10 mg / L of nitrate nitrogen and 3 mg / L of orthophosphate. The carbon-nitrogen ratio is adjusted to 4 by sodium acetate. The temperature is adjusted to 25±0.5°C for 10 days before the operation of the reactor, and the temperature is adjusted to 14±0.5°C for 45 days. The concentration of total nitrogen (TN) and total phosphorus (TP) in the effluent of the reactor is detected every two days by using the national standard detection method.

[0117] The results show that the denitrification efficiency of the filler prepared in Example 4 in the aquaculture tail water at room temperature (25±0.5°C) is 95.05%, and the phosphorus removal efficiency is 100.00%; the denitrification efficiency in the aquaculture tail water at low temperature is 85.44%, and the phosphorus removal efficiency is 99.75%.

[0118] It can be known from Examples 1 to 5 that the aquaculture tail water high-efficiency denitrification and phosphorus removal filler in Example 4 of the application exhibits excellent denitrification efficiency and phosphorus removal efficiency when treating aquaculture tail water at room temperature and low temperature, which is beneficial to realize the standard discharge of aquaculture tail water.

[0119] The above is only a preferred embodiment of the application, and does not limit the application in any form. Although the application has been disclosed as above with a preferred embodiment, it is not intended to limit the application. Any person skilled in the art can make many possible changes and modifications to the technical solution of the application by using the disclosed methods and technical contents without departing from the spirit and technical solution of the application. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments according to the technical essence of the application are still within the protection scope of the technical solution of the application.

Claims

1. A method for preparing a phosphorus and nitrogen removal composite packing, characterized in that, The steps include: (1) Adding polyvinyl alcohol and sodium alginate to water and heating to dissolve, thereby obtaining a hydrogel; the mass ratio of polyvinyl alcohol to sodium alginate is 5~10:1; the volume mass ratio of water to polyvinyl alcohol is 1L:50~150g; the heating temperature in step (1) is 80-100℃; the time is 1-5 hours; (2) Adding polyvinyl lactone, corn cob powder and zero-valent iron powder to the hydrogel in step (1) and stirring evenly to obtain a mixture; the mass ratio of polyvinyl lactone, corn cob powder and zero-valent iron powder is 55:20~60:20~60; the particle size of the corn cob powder is 75~147 µm; (3) Adding aerobic denitrifying bacteria P. furukawaii ZS1 bacterial solution was added to the mixture described in step (2), stirred evenly, and then frozen to form a solid shape. The aerobic denitrifying bacteria P. furukawaii The OD600 of ZS1 bacterial solution is 0.5~15; the aerobic denitrifying bacteria described in step (3) P. furukawaii The volume ratio of ZS1 bacterial solution to mixed solution is 1~5:10; the freezing temperature in step (3) is -30~-10℃ and the time is 12~36 hours; (4) the filler after freezing in step (3) is taken out and placed in a chemical crosslinking reagent solution for crosslinking reaction, and washed to obtain phosphorus-removing and nitrogen-removing composite filler; the chemical crosslinking reagent solution is a boric acid solution containing 2~6% CaCl2.

2. The preparation method according to claim 1, characterized in that, The temperature of the crosslinking reaction in step (4) is 0~10℃ and the time is 8~16 hours.

3. A phosphorus and nitrogen removal composite packing prepared by the preparation method according to any one of claims 1-2.

4. The application of the phosphorus and nitrogen removal composite packing material according to claim 3 in aquaculture wastewater treatment, characterized in that, The application involves inoculating activated sludge into an aerobic tank.

5. The application according to claim 4, characterized in that, The phosphorus and nitrogen removal composite packing material is used to treat aquaculture wastewater at a temperature of 10~30℃.

6. The application according to claim 4, characterized in that, The oxygen concentration in the aquaculture wastewater is 5-7 mg / L; the inoculation amount of activated sludge in the aerobic tank is 1-3 g / L.

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