A slow-release phosphorus removal agent for low-temperature water pollution, its preparation method and application

Abstract

This invention relates to a slow-release phosphorus removal agent, its preparation method, and its application, particularly to a slow-release phosphorus removal agent for phosphorus pollution in low-temperature water bodies, its preparation method, and its application. The components of the slow-release phosphorus removal agent are: 1500 parts potato starch, 160 parts sodium citrate, 100 parts ammonium sulfate, 20 parts sodium chloride, 60 parts potassium chloride, 10 parts magnesium sulfate, 10 parts calcium chloride, and 1 part maltose, with a weight ratio of maltose to pure water of 1:20000. The preparation method is as follows: Step 1, preparation of the potato starch-based slow-release agent; Step 2, starch microsphere molding and purification; Step 3, preparation of the finished slow-release agent. Beneficial effects: It effectively activates phosphorus-removing bacteria in low-temperature water bodies, significantly improving phosphate removal efficiency; its slow-release characteristics are suitable for low-temperature treatment needs, achieving long-term stable phosphorus control; it is environmentally friendly and economical, suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to a slow-release phosphorus removal agent, its preparation method, and its application, and particularly to a slow-release phosphorus removal agent for phosphorus pollution in low-temperature water bodies, its preparation method, and its application. Background Technology

[0002] Eutrophication has become a major water environment problem, and phosphorus, as a key limiting factor inducing eutrophication, is a core aspect of water environment management. Low-temperature aquatic environments significantly inhibit the metabolic activity of core functional microorganisms in biological phosphorus removal systems, leading to a sharp decline in their intracellular phosphorus uptake and storage rates. This directly results in a drastic reduction in biological phosphorus removal efficiency, ultimately causing the treated water to fail to meet total phosphorus standards, exacerbating the risk of eutrophication in low-temperature water bodies and increasing ecological and environmental pressures.

[0003] Chemical phosphorus removal is a common method, but traditional chemical phosphorus removal agents release rapidly, often within a few hours, and quickly flow downstream, failing to provide continuous water purification and limiting the time and scope of phosphorus removal. While some studies have attempted to slow the release rate by mixing water purification agents with slow-release chemical agents, most existing phosphorus removal agents cannot flexibly adjust their release rate according to the phosphorus content of the water, making it difficult to balance slow-release effect and phosphorus removal efficiency. Lanthanum-based phosphorus-locking agents, such as lanthanum-modified bentonite, are widely used for phosphorus removal. They remove phosphorus by forming insoluble lanthanum-phosphate complexes with free phosphates in the water. However, lanthanum is a rare earth element with high mining costs, making lanthanum-based phosphorus-locking agents expensive. Furthermore, current research has not yet proven that lanthanum is not potentially toxic to aquatic organisms, and the ecological risks of introducing large amounts of lanthanum-containing solids into natural water bodies and permanently depositing them in sediment are immeasurable.

[0004] Most phosphorus removal materials have low removal rates and unsatisfactory removal effects for low-concentration phosphorus. For example, salt-modified silicate cement phosphorus adsorbents are not suitable for removing low-concentration phosphorus, and cannot be recycled after being put into natural water bodies, causing secondary pollution to the water. The flocs produced after the hydration reaction of sulfoaluminate cement have a good removal effect on low-concentration phosphorus, but when the water content increases, the structural strength of the flocs decreases significantly, and the metal elements contained therein will be released into the environment. The preparation process of lanthanum-modified magnetic bentonite phosphorus removal materials is completed under alkaline conditions. When the pH is too high, the binding ability of lanthanum to phosphate decreases significantly, and its sedimentation is slow, which will cause water turbidity and affect the life activities of aquatic organisms.

[0005] To address the various problems existing in current phosphorus removal technologies in low-temperature water bodies, there is a need to develop a slow-release phosphorus removal agent that can adapt to low-temperature environments, has good slow-release performance, can flexibly adjust the release rate according to the phosphorus content of the water body, efficiently removes phosphorus pollution, and is environmentally friendly, so as to meet the actual needs of phosphorus pollution control in low-temperature water bodies. Summary of the Invention

[0006] The main purpose of this invention is to solve the problem that the single polyphosphate-accumulating bacteria have weak autonomous phosphorus removal efficiency in low-temperature environments, which cannot meet the phosphorus removal needs of high-latitude lakes in winter and low-temperature industrial wastewater tailwater, resulting in the continuous excess of total phosphorus in water bodies, which directly aggravates the risk of eutrophication and ecological pressure.

[0007] The second objective of this invention is to address the lack of effective means to target and activate polyphosphate-accumulating bacteria and enhance phosphorus removal efficiency in low-temperature microbial phosphorus removal technology, which makes it difficult to release the low-temperature phosphorus removal potential of polyphosphate-accumulating bacteria; and the inability to continuously stimulate polyphosphate-accumulating bacteria and achieve stable and efficient phosphorus removal effects due to the lack of sustained-release properties and short action cycles of conventional chemical agents.

[0008] Another objective of this invention is to address the problem that existing technologies lack stimulating agents that can adapt to the metabolic characteristics of indigenous microorganisms. Conventional agents cannot activate the phosphorus removal function of indigenous microorganisms, or the stimulating effect is short-lived due to uncontrollable release rates, resulting in the waste of the phosphorus removal potential of indigenous microorganisms and making it difficult to achieve low-cost and long-term treatment of phosphorus pollution in low-temperature water bodies.

[0009] In order to achieve the above objectives and solve the above problems, this invention provides a slow-release phosphorus removal agent for low-temperature water phosphorus pollution, its preparation method, and its application.

[0010] The slow-release phosphorus removal agent for low-temperature water phosphorus pollution provided by this invention comprises potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride, and maltose. The potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride, and maltose are added sequentially to a container, followed by the addition of pure water and stirring to prepare the mixture. The weight percentages of the aforementioned components are as follows: 1500 parts potato starch, 160 parts sodium citrate, 100 parts ammonium sulfate, 20 parts sodium chloride, 60 parts potassium chloride, 10 parts magnesium sulfate, 10 parts calcium chloride, and 1 part maltose. The weight ratio of maltose to pure water is 1:20000.

[0011] The present invention provides a method for preparing a slow-release phosphorus removal agent for low-temperature water phosphorus pollution, the method comprising the following steps:

[0012] Step 1: Preparation of potato starch-based sustained-release agent, the specific steps are as follows:

[0013] Step 1: Weigh out potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride, and maltose. Add them to a container in sequence, then add pure water and mix. The contents of each component by weight are as follows: potato starch 1500 parts, sodium citrate 160 parts, ammonium sulfate 100 parts, sodium chloride 20 parts, potassium chloride 60 parts, magnesium sulfate 10 parts, calcium chloride 10 parts, and maltose 1 part. The weight ratio of maltose to pure water is 1:20000.

[0014] Step 2: Stir magnetically until the solid is fully dispersed, forming a starch suspension;

[0015] Step 3: Place the container containing the starch suspension obtained in step 2 into an 80°C constant temperature water bath, stir magnetically at a speed of 300 r / min for 30 min until the starch is completely gelatinized and the solution is a uniform gel; remove and allow to cool naturally to room temperature to obtain an α-starch colloidal solution.

[0016] The second step, starch microsphere formation and purification, is as follows:

[0017] Step 1: Pour anhydrous ethanol into a container and place it in an ultrasonic cleaner for ultrasonic treatment. The ultrasonic cleaner has a power of 300W and a frequency of 40kHz.

[0018] Step 2: Add the α-starch colloidal solution dropwise to ethanol at a rate of 1 drop / second using a dropper, with the volume ratio of anhydrous ethanol to α-starch colloidal solution being 1:2.

[0019] Step 3: Continue sonication for 30 minutes to form a starch-ethanol suspension;

[0020] Step 4: Dispense the suspension into 50mL centrifuge tubes, centrifuge at 4000rpm for 15min, and discard the supernatant;

[0021] Step 5: Resuspend the precipitate in anhydrous ethanol. The volume ratio of anhydrous ethanol used for resuspension to the above α-starch colloidal solution is 1:4.

[0022] Step 6: After grinding into a paste, centrifuge again at 4000 rpm for 15 min and collect the precipitate;

[0023] The third step is the preparation of the sustained-release drug product, and the specific steps are as follows:

[0024] Step 1: Transfer the precipitate to a petri dish and dry it in a 30°C oven for 24 hours until constant weight is achieved;

[0025] Step 2: After taking it out, grind it into a uniform powder using a mortar and pestle, and pass it through a 100-mesh sieve to obtain a white solid powder of potato starch slow-release agent.

[0026] Chemical characteristics: It is a hard white solid, insoluble in water, and sinks to the lower water phase after being added to the water body; it continuously releases nutrient matrix starch and inorganic salts through slow water molecule wetting, thereby achieving long-term stimulation of polyphosphate growth.

[0027] The slow-release phosphorus removal agent for low-temperature water phosphorus pollution prepared by the above method can be applied in low-temperature water phosphorus pollution.

[0028] The beneficial effects of this invention are:

[0029] ① Highly activates phosphorus-removing bacteria in low-temperature water, significantly improving phosphate removal efficiency:

[0030] The slow-release agent provided by this invention can specifically address the problem of weak phosphorus removal efficiency of polyphosphate-accumulating bacteria at low temperatures. By continuously releasing active ingredients, it provides stable stimulation to polyphosphate-accumulating bacteria, significantly enhancing their low-temperature metabolic activity and significantly improving phosphate degradation efficiency. At the same time, it has a better activation effect on the phosphorus removal function of native microorganisms in aquatic bodies, fully tapping the phosphorus removal potential of natural microbial communities. Compared with scenarios without agent stimulation, the phosphate removal rate in low-temperature water can be increased by more than 50%, effectively solving the core pain point of excessive total phosphorus in low-temperature water.

[0031] ② The slow-release properties are suitable for low-temperature treatment needs, achieving long-term and stable phosphorus control:

[0032] The agent provided by this invention adopts a sustained-release design, avoiding the defects of conventional agents such as "instantaneous reaction and rapid loss". The active ingredients can be continuously released in low-temperature water bodies, which can provide long-term functional stimulation for polyphosphate-accumulating bacteria and indigenous flora, and avoid the problems of agent waste or excessively high local concentration. It is especially suitable for static / slow-flowing water bodies such as lakes in northern winters and low-temperature sewage treatment plant effluent, achieving "one-time addition and long-term phosphorus control" and reducing the manpower and cost investment of repeated addition.

[0033] ③ Environmentally friendly and economical, suitable for large-scale applications:

[0034] The technical solution provided by this invention avoids the ecological risks and high costs associated with traditional high-efficiency phosphorus removal materials. After application, there is no leaching of heavy metals or accumulation of harmful substances, and it is highly safe for aquatic organisms, meeting the environmental protection requirements for natural water body restoration. The agent can directly activate the original bacterial community in the water body without the need for additional exogenous bacterial strains, reducing the cost of bacterial cultivation and transportation. Moreover, the preparation process is simple and easy to industrialize, providing a low-cost and easily promoted technical solution for the treatment of phosphorus pollution in low-temperature water bodies in high-latitude regions and cold seasons. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the bacterial evolutionary tree described in this invention.

[0036] Figure 2This is a schematic diagram of the bacterial growth curve described in this invention.

[0037] Figure 3 This is a schematic diagram of the sustained-release drug formulation described in this invention. Detailed Implementation

[0038] The slow-release phosphorus removal agent for low-temperature water phosphorus pollution provided by this invention comprises potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride, and maltose. The potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride, and maltose are added sequentially to a container, followed by the addition of pure water and stirring to prepare the mixture. The weight percentages of the aforementioned components are as follows: 1500 parts potato starch, 160 parts sodium citrate, 100 parts ammonium sulfate, 20 parts sodium chloride, 60 parts potassium chloride, 10 parts magnesium sulfate, 10 parts calcium chloride, and 1 part maltose. The weight ratio of maltose to pure water is 1:20000.

[0039] The present invention provides a method for preparing a slow-release phosphorus removal agent for low-temperature water phosphorus pollution, the method comprising the following steps:

[0040] Step 1: Preparation of potato starch-based sustained-release agent, the specific steps are as follows:

[0041] Step 1: Weigh out potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride, and maltose. Add them to a container in sequence, then add pure water and mix. The contents of each component by weight are as follows: potato starch 1500 parts, sodium citrate 160 parts, ammonium sulfate 100 parts, sodium chloride 20 parts, potassium chloride 60 parts, magnesium sulfate 10 parts, calcium chloride 10 parts, and maltose 1 part. The weight ratio of maltose to pure water is 1:20000.

[0042] Step 2: Stir magnetically until the solid is fully dispersed, forming a starch suspension;

[0043] Step 3: Place the container containing the starch suspension obtained in step 2 into an 80°C constant temperature water bath, stir magnetically at a speed of 300 r / min for 30 min until the starch is completely gelatinized and the solution is a uniform gel; remove and allow to cool naturally to room temperature to obtain an α-starch colloidal solution.

[0044] The second step, starch microsphere formation and purification, is as follows:

[0045] Step 1: Pour anhydrous ethanol into a container and place it in an ultrasonic cleaner for ultrasonic treatment. The ultrasonic cleaner has a power of 300W and a frequency of 40kHz.

[0046] Step 2: Add the α-starch colloidal solution dropwise to ethanol at a rate of 1 drop / second using a dropper, with the volume ratio of anhydrous ethanol to α-starch colloidal solution being 1:2.

[0047] Step 3: Continue sonication for 30 minutes to form a starch-ethanol suspension;

[0048] Step 4: Dispense the suspension into 50mL centrifuge tubes, centrifuge at 4000rpm for 15min, and discard the supernatant;

[0049] Step 5: Resuspend the precipitate in anhydrous ethanol. The volume ratio of anhydrous ethanol used for resuspension to the above α-starch colloidal solution is 1:4.

[0050] Step 6: After grinding into a paste, centrifuge again at 4000 rpm for 15 min and collect the precipitate;

[0051] The third step is the preparation of the sustained-release drug product, and the specific steps are as follows:

[0052] Step 1: Transfer the precipitate to a petri dish and dry it in a 30°C oven for 24 hours until constant weight is achieved;

[0053] Step 2: After taking it out, grind it into a uniform powder using a mortar and pestle, and pass it through a 100-mesh sieve to obtain a white solid powder of potato starch slow-release agent. Agent characteristics: It is a hard white solid, insoluble in water, and sinks to the lower water phase after being put into the water body; it continuously releases the nutrient matrix starch and inorganic salts through the slow wetting of water molecules, so as to achieve long-term stimulation of polyphosphate growth.

[0054] The slow-release phosphorus removal agent for low-temperature water phosphorus pollution prepared by the above method can be applied in low-temperature water phosphorus pollution.

[0055] The specific implementation method is as follows:

[0056] Example 1:

[0057] Preparation and phosphorus removal performance verification of sustained-release agents

[0058] Preparation of experimental materials and reagents

[0059] Sample sources: surface soil from the lake shore (collected from a eutrophic lake in northern China, at a depth of 5-10 cm, transported under refrigeration at 4℃ after sampling, and processed within 24 hours); lake water (used to prepare sterilized lake water and simulate low-temperature polluted water).

[0060] Culture medium: PAM liquid medium (formulation: glucose 5.0 g / L, NH4Cl 1.0 g / L, KH2PO4 0.5 g / L, MgSO4·7H2O 0.2 g / L, CaCl2 0.1 g / L, pH adjusted to 7.0-7.2 with 1 mol / L HCl or NaOH, autoclaved at 121℃ for 20 min);

[0061] Pharmaceutical raw materials: potato starch (analytical grade), sodium citrate (analytical grade), ammonium sulfate (analytical grade), sodium chloride (analytical grade), potassium chloride (analytical grade), magnesium sulfate (analytical grade), calcium chloride (analytical grade), maltose (analytical grade), anhydrous ethanol (analytical grade);

[0062] Simulated polluted water body: Take the sterilized lake water from the above-mentioned lakes and add KH2PO4 to prepare a low-temperature simulated water body with a total phosphorus concentration of 100mg / L (4-5℃, consistent with the water temperature in northern winters).

[0063] Polyphosphate enrichment culture:

[0064] Step 1, Soil sample pretreatment: Weigh 1.00g of lake shore soil and add it to a sterile Erlenmeyer flask containing sterilized lake water. The mass ratio of surface soil to sterilized lake water is 1:50, and the density of sterilized lake water is 1g / mL. Shake at 180r / min for 30min to fully disperse the microorganisms. After standing for 5min, take the lower layer suspension as the inoculum source.

[0065] Step 2, Low-temperature enrichment: Take 1 mL of the inoculum obtained in Step 1 and transfer it to a sterile Erlenmeyer flask containing PAM liquid medium. The volume ratio of inoculum to PAM liquid is 1:100. Place it in a constant temperature shaker at 5℃ and culture it in the dark at 180 r / min to obtain the bacterial solution.

[0066] Step 3, Subculture and domestication: Every 2 days, take 10 mL of bacterial culture in a clean bench and transfer it to fresh PAM medium at a volume ratio of bacterial culture to fresh PAM medium of 1:10; enrich 4 times under the same conditions to obtain low-temperature adaptable polyphosphate-accumulating bacteria enrichment solution, and store at 4℃ for later use.

[0067] Identification of polyphosphate-accumulating bacteria:

[0068] In this invention, purified bacteria from a low-temperature-adaptive polyphosphate-accumulating culture were amplified using universal primers 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3') for 16S rDNA sequences in a 2×TsingKE Master Mix system. The PCR reaction mixture consisted of: 1 μL genomic DNA, 25 μL 2×TsingKE Master Mix, 1 μL 27F Primer (10 μM), 1 μL 1492R Primer (10 μM), and 22 μL dH2O. The PCR conditions were: pre-denaturation at 94℃ for 10 min, 30 cycles (94℃ for 30 s, 55℃ for 30 s, 72℃ for 1.5 min), and extension at 72℃ for 10 min. The purified PCR products were then sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing.

[0069] The 16S rDNA sequence of the strain was uploaded to the NCBI database and BLAST homology sequence alignment was performed. The results showed that the similarity with Pseudomonas putida (AY395005.1) was higher than 99%. The phylogenetic tree constructed using MEGA7 is as follows: Figure 1 As shown. Based on the above analysis results, this strain was identified as Pseudomonas putida JLU-01.

[0070] 16S rDNA sequence of *Pseudomonas putida* JLU-01 (NCBI ID: PX765048):

[0071]

[0072] Pseudomonas JLU-01 is a type of polyphosphate-accumulating bacteria. In this embodiment, Pseudomonas JLU-01 was selected as the target bacterium to verify the phosphorus removal performance of the sustained-release agent prepared in this invention.

[0073] Growth curve of JLU-01 in the example:

[0074] The strain appeared milky white in LB medium. Pure strain JLU-01 was picked and inoculated into sterilized LB liquid medium, and cultured at 25℃ and 180 rpm for 24 h to prepare seed culture. The seed culture was then diluted with 2% (OD200) solution. 600 =5) Inoculate into 100 ml of LB liquid medium and incubate at 25℃ and 180 r / min for a total of 48 h with shaking. OD values ​​are measured at 0, 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 30, 36, 42, and 48 h. 600 . with OD 600 Plot the growth curve with the vertical axis as the ordinate and the culture time as the horizontal axis.

[0075] The bacterial suspension was cultured using LB liquid medium with 2% seed culture added, and the OD of the bacterial suspension was measured periodically. 600 This is used to reflect the characteristics of the JLU-01 strain's proliferation over time during cultivation. For example... Figure 2 As shown, growth is slow from 0 to 1 hour, accelerates from 2 to 4 hours, enters the logarithmic growth phase from 4 to 12 hours with rapid growth, then slows down, reaches its maximum value at 16 hours and enters the stable phase, and shows signs of decline after 30 hours.

[0076] Preparation of potato starch-based sustained-release pharmaceuticals:

[0077] Preparation of α-starch colloidal solution: In a fume hood, weigh out 15.0g of potato starch, 1.6g of sodium citrate, 1.0g of ammonium sulfate, 0.2g of sodium chloride, 0.6g of potassium chloride, 0.1g of magnesium sulfate, 0.1g of calcium chloride, and 0.01g of maltose according to the formula, and add them all to a 500mL beaker; add 200mL of pure water to the beaker, place a magnetic stir bar, and stir magnetically at 300r / min for 10min until the solid is completely dispersed, forming a white starch suspension; place the beaker in an 80℃ constant temperature water bath and maintain magnetic stirring at 300r / min for 30min, observing the state of the suspension during this period: the initial white suspension gradually becomes transparent, and finally forms a uniform light white gelatinous liquid, indicating that the starch is completely gelatinized; turn off the water bath, remove the beaker, and allow it to cool naturally to room temperature to obtain the α-starch colloidal solution.

[0078] Starch microsphere formation and purification: Pour 100 mL of anhydrous ethanol into a 250 mL beaker. Place the beaker in an ultrasonic cleaner and add pure water until it covers half of the beaker wall. Turn on the ultrasonic cleaner (300 W, 40 kHz). Use a dropper to draw up the cooled α-starch colloidal solution and add it dropwise to the ultrasonic anhydrous ethanol at a rate of 1 drop / second. Continue ultrasonication during the addition process. After the addition is complete, continue ultrasonication for 30 min to form a white, milky starch-ethanol suspension. Divide the suspension into two 50 mL sterile centrifuge tubes and centrifuge at 4000 rpm for 15 min at room temperature. After centrifugation, a white precipitate will be visible at the bottom of the tube. Discard the upper transparent ethanol solution. Add 25 mL of anhydrous ethanol to each centrifuge tube and grind the precipitate into a paste with a sterile glass rod. Centrifuge again at 4000 rpm for 15 min, discard the supernatant, and collect the white wet precipitate at the bottom of the tube (i.e., the white, wet precipitate). Figure 3 ), to complete purification (removal of unreacted small molecule impurities).

[0079] Preparation of sustained-release drug product: The precipitate was dried at 30℃ for 24 h to constant weight, ground and passed through a 100-mesh sieve to obtain a white powdered sustained-release drug.

[0080] Experimental Groups:

[0081] Blank control group: 500 mL simulated water + 10 mL polyphosphate-accumulating solution;

[0082] Conventional reagent group: 500mL simulated water + 0.5g untreated starch + 10mL polyphosphate-accumulating solution;

[0083] Slow-release agent group: 500mL simulated water + 0.5g slow-release agent + 10mL polyphosphate enrichment solution;

[0084] Culture conditions: Incubate at 5℃ in the dark for 15 days.

[0085] Test method: The total phosphorus concentration was determined according to GB / T 11893-1989, and samples were taken at 0, 1, 3, 7 and 15 days.

[0086] The results are shown in the table below:

[0087] Incubation time (d) Total phosphorus concentration (mg / L) in the blank control group Total phosphorus concentration (mg / L) in the conventional drug group Total phosphorus concentration (mg / L) of the reagent group of this invention 0 1.50 1.50 1.50 1 1.42 0.85 1.02 3 1.38 0.91 0.65 7 1.35 1.03 0.38 15 1.32 1.15 0.12

[0088] Blank control group: Only polyphosphate-accumulating bacteria were added. Under low temperature, the autonomous phosphorus removal efficiency of polyphosphate-accumulating bacteria was weak. After 15 days, the total phosphorus concentration decreased by only 0.18 mg / L, and the removal rate was only 12%, which confirmed the technical problem of "insufficient phosphorus removal efficiency of single polyphosphate-accumulating bacteria under low temperature conditions".

[0089] Conventional agent group: When starch without slow release is added, the total phosphorus concentration drops to 0.85 mg / L (removal rate 43.3%) in the initial stage (1 day) due to the rapid release of starch. However, after the starch is depleted, polyphosphate bacteria lack nutritional stimulation, and the total phosphorus concentration rises again. The removal rate is only 23.3% after 15 days, which reflects the defects of "conventional agents with short action cycle and poor continuous phosphorus control ability".

[0090] The reagent group of this invention: the reagent releases the nutrient matrix continuously through the slow wetting of water molecules. The total phosphorus concentration continuously decreases to 0.12 mg / L within 15 days, with a removal rate of 92.0%, and there is no concentration rebound. This fully demonstrates that the reagent of this invention can effectively activate polyphosphate-accumulating bacteria and is suitable for low-temperature water environments to achieve stable phosphorus removal, thus solving the core difficulties of the prior art.

[0091] Example 2:

[0092] Adaptability verification of different starch raw materials

[0093] Replacing potato starch with corn starch and following the same steps as in Example 1, the total phosphorus removal rate after 15 days was 81.5%, and the slow-release period was shortened by about 6%; this indicates that the present invention is applicable to a variety of starch sources and has raw material flexibility.

[0094] Example 3:

[0095] Winter effluent from a municipal wastewater treatment plant in northern China (total phosphorus 1.2 mg / L, water temperature 5℃) was collected, and a slow-release agent was added to a concentration of 1 g / m³. After standing for 7 days, the total phosphorus concentration stabilized below 0.3 mg / L, meeting the Class A standard of the "Discharge Standard of Pollutants for Urban Wastewater Treatment Plants". The duckweed growth inhibition experiment showed that the agent was non-toxic to aquatic organisms (survival rate ≥95%).

[0096] Example 4:

[0097] Adaptability verification at different incubation temperatures

[0098] The enrichment temperature of polyphosphate-accumulating bacteria was adjusted to 4℃ and 10℃, and the rest was the same as in Example 1; the total phosphorus removal rates of the bacterial solutions enriched at the two temperatures, when combined with slow-release agents, were 82.1% and 84.7% respectively after 15 days; indicating that the present invention is applicable to different low-temperature water environments.

Claims

1. A slow-release phosphorus removal agent for low-temperature water body phosphorus pollution, characterized in that: The low-temperature water body phosphorus pollution slow-release type phosphorus removal agent comprises potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride and maltose, and is prepared by adding the potato starch, the sodium citrate, the ammonium sulfate, the sodium chloride, the potassium chloride, the magnesium sulfate, the calcium chloride and the maltose into a container in sequence and then adding pure water to mix and stir, wherein the contents of the potato starch, the sodium citrate, the ammonium sulfate, the sodium chloride, the potassium chloride, the magnesium sulfate, the calcium chloride and the maltose are 1500 parts by weight, 160 parts by weight, 100 parts by weight, 20 parts by weight, 60 parts by weight, 10 parts by weight, 10 parts by weight and 1 part by weight respectively, and the ratio by weight of the maltose to the pure water is 1:20000. ​ The first step is to prepare the potato starch-based slow-release agent, and the specific steps are as follows: Step 1, weigh the potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride and maltose, and add them into a container in sequence, then add pure water to mix and stir, wherein the weights of the potato starch, the sodium citrate, the ammonium sulfate, the sodium chloride, the potassium chloride, the magnesium sulfate, the calcium chloride and the maltose are 1500 parts, 160 parts, 100 parts, 20 parts, 60 parts, 10 parts, 10 parts and 1 part respectively, and the ratio by weight of the maltose to the pure water is 1:20000; Step 2, magnetically stir until the solids are fully dispersed to form a starch suspension; Step 3, place the container with the starch suspension prepared in step 2 in a 80℃ constant temperature water bath, magnetically stir at a speed of 300r / min, and keep for 30min until the starch is completely gelatinized and the solution is uniform gel; The second step is to form and purify the starch microspheres, and the specific steps are as follows: Step 1, pour anhydrous ethanol into a container and place it in an ultrasonic cleaner, and the power of the ultrasonic cleaner is 300W and the frequency is 40kHz; Step 2, add the α-gelatinized starch colloid solution drop by drop into the ethanol at a rate of 1 drop per second, and the volume ratio of anhydrous ethanol to α-gelatinized starch colloid solution is 1:2; Step 3, continue to ultrasonic for 30min to form a starch-ethanol suspension; Step 4, divide the suspension into 50mL centrifuge tubes and centrifuge at 4000rpm for 15min, and discard the supernatant; Step 5, resuspend the precipitate with anhydrous ethanol, and the volume ratio of the anhydrous ethanol used for resuspension to the above-mentioned α-gelatinized starch colloid solution is 1:4; Step 6, grind into paste and then centrifuge at 4000rpm for 15min, and collect the precipitate; The third step is to prepare the finished slow-release agent, and the specific steps are as follows: Step 1, transfer the precipitate to a culture dish and dry it in a 30℃ oven until the weight is constant; Step 2, take it out and grind it into a uniform powder with a mortar, pass it through a 100 mesh sieve, and obtain a white solid powder of the potato starch slow-release agent.

2. The low-temperature water body phosphorus pollution slow-release type phosphorus removal agent according to claim 1 can be used for phosphorus removal in low-temperature water body phosphorus pollution, and the agent is a hard white solid and insoluble in water. After being put into the water body, it sinks to the lower water phase; through slow infiltration of water molecules, it continuously releases nutrient substrates starch and inorganic salts, and realizes long-term stimulation of the growth of phosphorus accumulating bacteria.

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