Slow-release type phosphorus removal agent for phosphorus pollution of low-temperature water body as well as preparation method and application of slow-release type phosphorus removal agent

Abstract

The invention relates to a slow-release phosphorus removal agent as well as a preparation method and application thereof, in particular to a slow-release phosphorus removal agent for phosphorus pollution of a low-temperature water body as well as a preparation method and application thereof. The slow-release phosphorus removal agent comprises the following components in parts by weight: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, wherein the weight ratio of the maltose to the pure water is 1: 20000. The preparation method comprises the following steps: 1, preparing the potato starch-based slow-release medicament; 2, forming and purifying starch microspheres; and step 3, preparing a sustained-release medicament finished product. The method has the beneficial effects that low-temperature water body phosphorus removal flora is efficiently activated, and the phosphate removal efficiency is remarkably improved; the slow-release characteristic meets the low-temperature treatment requirement, and long-acting stable phosphorus control is achieved; and the method is environment-friendly, excellent in economical efficiency and suitable for large-scale application.

Description

TECHNICAL FIELD

[0001] The present application relates to a slow-release phosphorus removal agent and a preparation method and application thereof, in particular to a slow-release phosphorus removal agent for low-temperature water body phosphorus pollution and a preparation method and application thereof. BACKGROUND

[0002] At present, water eutrophication has become a major water environmental problem, and phosphorus, as a key limiting factor for inducing water eutrophication, its pollution control is one of the core links of water environment management. The low-temperature water body environment can significantly inhibit the metabolic activity of the core functional microorganisms in the biological phosphorus removal system, resulting in a significant decrease in the uptake and storage rate of intracellular phosphorus, which directly leads to a sharp decrease in the efficiency of biological phosphorus removal, and ultimately causes the total phosphorus in the treated water body to be difficult to meet the standard, and aggravates the risk of eutrophication and ecological environmental pressure of low-temperature water body.

[0003] Chemical phosphorus removal is a common way of phosphorus removal, but the traditional chemical phosphorus removal drug has a fast release speed, and often ends in a few hours, and is quickly flowed to the downstream under the action of water flow, and cannot continuously purify the water body, and the phosphorus removal time and range are limited. Although there are studies on mixing water purification drugs with chemical release agents to slow down the release speed, but most of the existing phosphorus removal agents cannot flexibly adjust the slow-release rate according to the phosphorus content of the water body, and it is difficult to balance the slow-release effect and the phosphorus removal efficiency. The lanthanum-modified bentonite and other lanthanum-based phosphorus locking agents are widely used in phosphorus removal, which removes phosphorus by forming a difficult-to-dissolve lanthanum-phosphate complex with free phosphate in water. However, lanthanum is a rare earth element, and the mining cost is high, resulting in high price of lanthanum-based phosphorus locking agent. In addition, existing studies have not yet proved that lanthanum metal has no potential toxicity to aquatic organisms, and a large amount of lanthanum-containing solids are poured into natural water bodies and permanently deposited in the sediment, and the ecological risk is still immeasurable.

[0004] Most phosphorus removal materials have low removal rate and unsatisfactory removal effect for low-concentration phosphorus, such as salt-modified silicate cement phosphorus removal adsorbent, which is not suitable for low-concentration phosphorus removal, and cannot be recycled after being poured into natural water bodies, which will cause secondary pollution to the water body; the floc produced by the hydration reaction of sulphoaluminate cement has good removal effect on low-concentration phosphorus, but the floc structure strength decreases significantly under the condition of increasing water content, and the contained metal elements will be released into the environment; the preparation process of lanthanum-modified magnetic bentonite phosphorus removal material is completed under alkaline conditions, and when the pH is too high, the binding capacity of lanthanum and phosphate will decrease significantly, and the settling is slow, which will cause water turbidity and affect the life activities of aquatic organisms.

[0005] In view of the various problems existing in the low-temperature water body of the existing phosphorus removal technology, it is necessary to develop a slow-release phosphorus removal functional agent which can adapt to low-temperature environment, 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 low-temperature water body phosphorus pollution control. SUMMARY

[0006] The main purpose of the present application is to solve the problem that the self-dephosphorization efficiency of single PAOs is weak in low-temperature environment, which cannot meet the phosphorus removal demand in winter lakes in high-latitude regions, low-temperature industrial wastewater tail water and other scenes, resulting in continuous over-standard of total phosphorus in water bodies and directly increasing the risk of eutrophication and ecological pressure.

[0007] The second purpose of the present application is to solve the problem that the low-temperature microbial dephosphorization technology lacks effective means to target activate PAOs and strengthen dephosphorization efficiency, so that the low-temperature dephosphorization potential of PAOs is difficult to release; and the conventional chemical agents cannot provide stimulation for PAOs continuously due to the lack of slow-release characteristics and short action period, so that it is difficult to achieve stable and efficient dephosphorization effect.

[0008] The further purpose of the present application is to solve the problem that the prior art lacks stimulating agents that can adapt to the metabolic characteristics of PAOs, the conventional agents cannot activate the dephosphorization function of indigenous bacteria, or the stimulating effect is short-term due to uncontrollable release rate, resulting in waste of the dephosphorization potential of indigenous microorganisms, and it is difficult to achieve low-cost and long-acting treatment of phosphorus pollution in low-temperature water bodies.

[0009] The present application provides a slow-release dephosphorization agent for phosphorus pollution in low-temperature water bodies and a preparation method and application thereof.

[0010] The slow-release dephosphorization agent for phosphorus pollution in low-temperature water bodies provided by the present application 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 and stirring to mix, wherein the content of each component is as follows: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, and the ratio of maltose to pure water is 1:20000.

[0011] The preparation method of the slow-release dephosphorization agent for phosphorus pollution in low-temperature water bodies provided by the present application comprises the following steps:

[0012] The first step is to prepare a potato starch-based slow-release agent, and the specific steps are as follows:

[0013] Step 1, weigh the potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride and maltose, add them into the container in turn, then add pure water and mix and stir, the content of each component is as follows: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, the ratio of maltose to pure water is 1:20000 by weight;

[0014] Step 2, magnetic stirring until the solids are fully dispersed to form a starch suspension;

[0015] Step 3, place the container with the starch suspension prepared in step 2 in a 80℃ constant temperature water bath, magnetic stirring at a speed of 300r / min for 30min until the starch is completely gelatinized and the solution is uniform gel; after taking out, cool it to room temperature naturally to obtain the α-converted starch colloidal solution;

[0016] Second step, starch microsphere formation and purification, the specific steps are as follows:

[0017] Step 1, pour anhydrous ethanol into the container, and place it in an ultrasonic cleaner for ultrasonic treatment, the power of the ultrasonic cleaner is 300W and the frequency is 40kHz;

[0018] Step 2, add the α-converted starch colloidal solution drop by drop into the ethanol at a rate of 1 drop per second, the volume ratio of anhydrous ethanol to α-converted starch colloidal solution is 1:2;

[0019] Step 3, continue ultrasonic treatment for 30min to form a starch-ethanol suspension;

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

[0021] Step 5, resuspend the precipitate with anhydrous ethanol, the volume ratio of anhydrous ethanol used for resuspension to the above α-converted starch colloidal solution is 1:4;

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

[0023] Third step, preparation of sustained-release drug product, the specific steps are as follows:

[0024] Step 1, transfer the precipitate to a culture dish and dry it in a 30℃ oven for 24h until the weight is constant;

[0025] Step 2, take it out and grind it into a uniform powder with a mortar, pass it through a 100 mesh sieve to obtain white solid powder of potato starch sustained-release drug.

[0026] Pharmaceutical properties: hard white solid, insoluble in water, sinks to the lower water phase after being put into the water; slowly infiltrated by water molecules, continuously releases nutrient matrix starch and inorganic salt, realizes long-acting stimulation to the growth of phosphorus accumulating bacteria.

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

[0028] The beneficial effects of the present application are:

[0029] ①Highly activate phosphorus removal bacteria in low-temperature water bodies, significantly improve the phosphorus removal efficiency:

[0030] The slow-release agent provided by the present application can specifically solve the problem of weak self-phosphorus removal effect of phosphorus accumulating bacteria at low temperature - by continuously releasing active ingredients, providing stable stimulation to phosphorus accumulating bacteria, greatly strengthening the low-temperature metabolic activity of phosphorus accumulating bacteria, and significantly improving the phosphorus removal efficiency; at the same time, the phosphorus removal function of the indigenous microorganisms in the water body is more effectively activated, and the phosphorus removal potential of the natural bacterial community is fully tapped, compared with the scene without agent stimulation, the phosphorus removal rate of the low-temperature water body can be increased by more than 50%, effectively solving the core pain point of total phosphorus exceeding the standard in low-temperature water bodies.

[0031] ②The slow-release property is suitable for low-temperature treatment needs, and realizes long-acting and stable phosphorus control:

[0032] The agent provided by the present application adopts slow-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 to phosphorus accumulating bacteria and indigenous bacterial community, and also avoid the problems of agent waste or local high concentration, especially suitable for static / calm water bodies such as northern winter lakes and low-temperature sewage plant effluent, realizing "one-time addition, long-acting phosphorus control", reducing the labor and cost investment of repeated addition.

[0033] ③Environment-friendly and economical, suitable for large-scale application:

[0034] The technical solution provided by the present application avoids the ecological risk and high cost problems of traditional high-efficiency phosphorus removal materials, and there is no heavy metal leaching or harmful substance accumulation after addition, which is high in safety to aquatic organisms and meets the environmental protection needs of natural water body restoration; the agent can directly activate the original bacterial community in the water body, without the need for additional addition of exogenous bacterial strains, reducing the cost of bacterial strain culture and transportation, and the preparation process is simple, which is convenient for industrialized production, and provides a low-cost and easy-to-promote technical solution for the treatment of phosphorus pollution in low-temperature water bodies in high-latitude areas and cold seasons. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The bacterial development phylogenetic tree described in the present application is shown in the figure.

[0036] Figure 2A schematic diagram of the bacterial growth curve described in the present application.

[0037] Figure 3 A schematic diagram of the slow-release drug form described in the present application. DETAILED DESCRIPTION

[0038] The slow-release phosphorus removal agent for low-temperature water body phosphorus pollution provided by the present application comprises potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride and maltose, and is prepared by sequentially 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 and then adding pure water to mix and stir, wherein the content of each component is as follows: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, and the ratio by weight of the maltose to the pure water is 1:20000.

[0039] The preparation method of the slow-release phosphorus removal agent for low-temperature water body phosphorus pollution provided by the present application comprises the following steps:

[0040] First step, preparation of the potato starch-based slow-release agent, and the specific steps are as follows:

[0041] Step 1, weigh the potato starch, the sodium citrate, the ammonium sulfate, the sodium chloride, the potassium chloride, the magnesium sulfate, the calcium chloride and the maltose, sequentially add them into a container, then add pure water to mix and stir, wherein the content of each component is as follows: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, and the ratio by weight of the maltose to the pure water is 1:20000.

[0042] Step 2, magnetically stir until the solids are fully dispersed to form a starch suspension;

[0043] Step 3, place the container containing the starch suspension prepared in step 2 in an 80℃ constant-temperature water bath, magnetically stir at a speed of 300r / min, and keep the starch gelatinized for 30min until the solution becomes a uniform gel; then take it out and naturally cool it to room temperature to obtain an alpha-gelatinized starch colloid solution;

[0044] Second step, formation and purification of the starch microspheres, and the specific steps are as follows:

[0045] Step 1, pour anhydrous ethanol into a container, and place it in an ultrasonic cleaning machine for ultrasonic treatment, wherein the power of the ultrasonic cleaning machine is 300W and the frequency is 40kHz;

[0046] Step 2, add the alpha-starch colloidal solution drop by drop into ethanol at a rate of 1 drop per second using a rubber bulb dropper, and the ratio of anhydrous ethanol to alpha-starch colloidal solution is 1:2 by volume;

[0047] Step 3, continue ultrasonic treatment for 30 min to form a starch-ethanol suspension;

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

[0049] Step 5, resuspend the precipitate with anhydrous ethanol, and the ratio of anhydrous ethanol used for resuspension to the above alpha-starch colloidal solution is 1:4 by volume;

[0050] Step 6, grind into a paste and then centrifuge at 4000 rpm for 15 min, and collect the precipitate;

[0051] Third step, preparation of slow-release drug product, the specific steps are as follows:

[0052] Step 1, transfer the precipitate to a culture dish and dry in a 30°C oven for 24 h to constant weight;

[0053] Step 2, after taking out, grind into a uniform powder with a mortar, and pass through a 100-mesh sieve to obtain white solid powder of potato starch slow-release drug, and the drug properties are: hard white solid, insoluble in water, sinks to the lower water phase after being thrown into water; slowly infiltrated by water molecules, continuously releases nutrient substrate starch and inorganic salts, and realizes long-acting stimulation to growth of phosphorus accumulating bacteria.

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

[0055] The specific implementation is as follows:

[0056] Example 1:

[0057] Preparation of slow-release drug and verification of phosphorus removal performance

[0058] Preparation of experimental materials and reagents

[0059] Sample source: surface soil of lake shore (collected from a certain eutrophic lake in the north, sampling depth 5-10 cm, 4°C cold storage transportation after sampling, and processing within 24 h); lake water of the lake (used for preparing sterilized lake water and simulating low-temperature polluted water body);

[0060] Culture medium: PAM liquid medium (formula: 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, adjust pH to 7.0-7.2 with 1 mol / l HCl or NaOH, 121℃ high pressure steam sterilization for 20 min);

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

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

[0063] Polyphosphorus bacteria enrichment culture:

[0064] Step 1, soil pretreatment: weigh 1.00 g of lake shore soil, add sterile Erlenmeyer flask containing sterilized lake water, according to the mass ratio of surface soil to sterilized lake water is 1:50, the density of sterilized lake water is 1 g / mL, oscillate at 180 r / min for 30 min to make the microorganisms fully dispersed; after standing for 5 min, take the lower suspension as the inoculum source;

[0065] Step 2, low-temperature enrichment: take 1 mL of the inoculum prepared in step 1 and transfer it to a sterile Erlenmeyer flask containing PAM liquid medium, according to the volume ratio of inoculum to PAM liquid is 1:100, place it in a 5℃ constant temperature shaker under the condition of 180 r / min, avoid light, get the bacterial liquid;

[0066] Step 3, subculture domestication: every 2 days, take 10 mL of bacterial liquid in a super clean bench and transfer it to fresh PAM medium, according to the volume ratio of bacterial liquid to fresh PMA medium is 1:10; continuously enrich under the same condition for 4 times, obtain low-temperature adaptive polyphosphorus bacteria enrichment liquid, store at 4℃ for standby;

[0067] Identification of polyphosphorus bacteria:

[0068] The purified bacteria in the low-temperature adaptive polyphosphorus bacteria enrichment liquid are taken as the PCR reaction primers of universal primer 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3') of 16S rDNA sequence, and 2×TsingKE Master Mix system is used for PCR amplification. The PCR reaction system is: genomic DNA 1 μL, 2×TsingKE Master Mix 25 μL, 27F Primer (10 μM) 1 μL, 1492R Primer (10 μM) 1 μL, dH2O 22 μL. The PCR reaction condition is: pre-denaturation 94℃ 10 min, 30 cycles (94℃ 30 s, 55℃ 30 s, 72℃ 1.5 min), extension 72℃ 10 min. After the obtained PCR product is purified, it is sent to Shenguo Bioengineering (Shanghai) Co., Ltd. for sequencing.

[0069] The 16S rDNA sequence of the strain is uploaded to the NCBI database and BLAST homologous sequence comparison is performed, and the result shows that the similarity with Pseudomonas putida (AY395005.1) is higher than 99%, and the phylogenetic tree constructed by MEGA7 is as shown in Figure 1 The strain is identified as Pseudomonas putida JLU-01 in combination with the above analysis result.

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

[0071]

[0072] Pseudomonas JLU-01 is one of the PAOs, and in this embodiment, Pseudomonas JLU-01 is used as the target bacteria to verify the phosphorus removal performance of the slow-release agent prepared in the application.

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

[0074] The strain appears milky white in the LB medium, and the pure strain JLU-01 is inoculated in the sterilized LB liquid medium, cultured at 25°C and 180 r / min for 24 h to prepare the seed liquid. The seed liquid is inoculated into 100 ml of the LB liquid medium at 2% (OD 600 =5), and the cumulative culture is carried out at 25°C and 180 r / min for 48 h, and the OD 600 is measured at 0, 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 30, 36, 42 and 48 h, respectively. The growth curve is drawn with the OD 600 as the vertical coordinate and the culture time as the horizontal coordinate.

[0075] The LB liquid medium is used to culture the 2% seed liquid, and the OD 600 of the bacterial suspension is measured at regular time intervals to reflect the growth of the JLU-01 strain with time during the culture process. As shown in FIG. 1, the growth is slow at 0-1 h, the growth accelerates at 2-4 h, the logarithmic growth phase is entered at 4-12 h, the growth is rapid, then the growth slows down, reaches the maximum at 16 h, enters the stable phase, and has signs of decline after 30 h. Figure 2

[0076] Preparation of the potato starch-based slow-release agent:

[0077] Preparation of the α-modified starch colloidal solution: in a fume hood, the following ingredients are weighed according to the formula: 15.0 g of potato starch, 1.6 g of sodium citrate, 1.0 g of ammonium sulfate, 0.2 g of sodium chloride, 0.6 g of potassium chloride, 0.1 g of magnesium sulfate, 0.1 g of calcium chloride, and 0.01 g of maltose, which are all added into a 500 mL beaker; 200 mL of pure water is added into the beaker, a magnetic stirrer is placed in the beaker, and the magnetic stirring is carried out at 300 r / min for 10 min until the solids are completely dispersed to form a white starch suspension; the beaker is placed in an 80°C constant-temperature water bath, the magnetic stirring is continued at 300 r / min for 30 min, and the state of the suspension is observed during the period: the initial white suspension gradually becomes transparent, and finally a uniform light white gelatinous liquid is formed, which indicates that the starch is completely gelatinized; the water bath is turned off, the beaker is taken out, and the beaker is naturally cooled to room temperature to obtain the α-modified starch colloidal solution.

[0078] ​Starch microspheres forming and purifying: 100 mL of anhydrous ethanol was poured into a 250 mL beaker, the beaker was placed in an ultrasonic cleaner, and pure water was added to cover the beaker wall 1 / 2, and the ultrasonic (300 W, 40 kHz) was started; the cooled α-starch colloid solution was taken with a rubber dropper, and was added dropwise into the ultrasonic state of anhydrous ethanol at a rate of 1 drop per second, and the ultrasonic was continued during the dropping process, and after the dropping was completed, the ultrasonic was continued for 30 min, and a white and turbid starch-ethanol suspension was formed; the suspension was evenly divided into two 50 mL sterile centrifuge tubes, and was placed in a centrifuge, and the speed was set to 4000 rpm, and the centrifugation was carried out at room temperature for 15 min; after the centrifugation was completed, white precipitate was visible at the bottom of the tube, and the transparent ethanol solution was discarded; 25 mL of anhydrous ethanol was added to each centrifuge tube, and the precipitate was ground into a paste with a sterile glass rod, and the centrifugation was carried out again at 4000 rpm for 15 min, and the supernatant was discarded, and the white wet block-shaped precipitate (i.e. Figure 3 ) at the bottom of the tube was collected, and the purification (removal of unreacted small molecular impurities) was completed.

[0079] Preparation of the finished sustained-release medicament: the precipitate was dried at 30°C for 24 h to a constant weight, and was ground through a 100 mesh sieve to obtain a white powder of the sustained-release medicament.

[0080] Experimental grouping:

[0081] Blank control group: 500 mL of simulated water body + 10 mL of polyphosphorus bacteria enrichment liquid;

[0082] Conventional medicament group: 500 mL of simulated water body + 0.5 g of untreated starch + 10 mL of polyphosphorus bacteria enrichment liquid;

[0083] Sustained-release medicament group: 500 mL of simulated water body + 0.5 g of sustained-release medicament + 10 mL of polyphosphorus bacteria enrichment liquid;

[0084] Culturing conditions: 5°C, light-avoiding, and static culturing for 15 days;

[0085] Detection method: the total phosphorus concentration was determined according to GB / T 11893-1989, and the sampling was carried out at 0, 1, 3, 7, and 15 days.

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

[0087] Culture time (d) Total phosphorus concentration of blank control group (mg / L) Total phosphorus concentration of conventional medicament group (mg / L) Total phosphorus concentration of medicament group of the present application (mg / L) 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 polyphosphorus bacteria was added, and the self-phosphorus removal efficiency of the polyphosphorus bacteria was weak at low temperature, and the total phosphorus concentration only decreased by 0.18 mg / L after 15 days, and the removal rate was only 12%, which verified the technical problem of "insufficient phosphorus removal efficiency of single polyphosphorus bacteria at low temperature";

[0089] Conventional agent group: add starch without slow-release, in the initial stage (1d), due to the rapid release of starch, the total phosphorus concentration decreases to 0.85mg / L (removal rate 43.3%), but the subsequent starch is depleted, the polyphosphorus bacteria lack nutritional stimulation, the total phosphorus concentration rebounds, and the removal rate is only 23.3% in 15d, which embodies the defects of "short action period of conventional agent and poor sustained phosphorus control ability";

[0090] The agent group of the application: the agent continuously releases the nutrient matrix through the slow infiltration of water molecules, the total phosphorus concentration decreases to 0.12mg / L within 15 days, and the removal rate is 92.0%, and there is no concentration rebound phenomenon, which fully proves that the agent of the application can activate the polyphosphorus bacteria for a long time, and is suitable for low-temperature water body environment, realizes the stable removal of phosphorus, and solves the core difficulty of the prior art.

[0091] Example 2:

[0092] Adaptability verification of different starch raw materials

[0093] Replace the potato starch with corn starch, and the remaining steps are the same as in Example 1, and the total phosphorus removal rate is 81.5% in 15 days, and the slow-release period is shortened by about 6%; it is shown that the application is suitable for a variety of starch sources and has raw material flexibility.

[0094] Example 3:

[0095] Take the winter tail water (total phosphorus 1.2mg / L, water temperature 5℃) of a municipal wastewater treatment plant in the north, add slow-release agent to 1g / m³, and stand for 7 days, the total phosphorus concentration is stable below 0.3mg / L, reaching the first level A standard of "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant"; the duckweed growth inhibition experiment shows that the agent is non-toxic to aquatic organisms (survival rate ≥95%).

[0096] Example 4:

[0097] Adaptability verification of different culture temperatures

[0098] The polyphosphorus bacteria enrichment temperature is adjusted to 4℃ and 10℃, and the rest is the same as in Example 1; the bacteria liquid enriched at two kinds of temperature is matched with slow-release agent, and the total phosphorus removal rate is 82.1% and 84.7% respectively in 15 days; it is shown that the application is suitable for different low-temperature water body environment.

Claims

1. A slow-release phosphorus removal agent for low-temperature water body phosphorus pollution, characterized in that: It comprises potato starch, sodium citrate, ammonium sulfate, sodium chloride, potassium chloride, magnesium sulfate, calcium chloride and maltose, and is prepared by adding the above components into a container in sequence and then adding pure water to mix and stir. The content of each component is as follows: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, with the ratio of maltose to pure water being 1:20000. ​ 2. A method for preparing a slow-release phosphorus removal agent for low-temperature water body phosphorus pollution, characterized in that: The method comprises the following steps: Firstly, the potato starch-based sustained-release medicament is prepared, and the specific steps are as follows: Step 1: weigh 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. The weight of each component is as follows: 1500 parts of potato starch, 160 parts of sodium citrate, 100 parts of ammonium sulfate, 20 parts of sodium chloride, 60 parts of potassium chloride, 10 parts of magnesium sulfate, 10 parts of calcium chloride and 1 part of maltose, with the ratio of maltose to pure water being 1:20000. Step 2: magnetically stir until the solids are fully dispersed to form a starch suspension. Step 3: place the container containing the starch suspension prepared in step 2 in an 80℃ constant-temperature water bath, magnetically stir at a speed of 300r / min, and gelatinize the starch for 30min until the solution becomes a uniform gel. Then, take it out and naturally cool it to room temperature to obtain an α-starch gel solution. Secondly, the starch microspheres are formed and purified, and the specific steps are as follows: Step 1: pour anhydrous ethanol into a container and place it in an ultrasonic cleaner for ultrasonic treatment. The power of the ultrasonic cleaner is 300W and the frequency is 40kHz. Step 2: use a rubber bulb dropper to add the α-starch gel solution into the ethanol at a rate of 1 drop per second, with the volume ratio of anhydrous ethanol to α-starch gel solution being 1:

2. Step 3: continue ultrasonic treatment for 30min to form a starch-ethanol suspension. Step 4: divide the suspension into 50mL centrifuge tubes and centrifuge at 4000rpm for 15min, then discard the supernatant. Step 5: resuspend the precipitate with anhydrous ethanol, with the volume ratio of the anhydrous ethanol used for resuspension to the above α-starch gel solution being 1:

4. Step 6: grind the mixture into a paste and then centrifuge at 4000rpm for 15min to collect the precipitate. Thirdly, the finished sustained-release medicament is prepared, 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, then pass it through a 100-mesh sieve to obtain a white solid powder of the potato starch sustained-release medicament.

3. The slow-release phosphorus removal agent for low-temperature water body phosphorus pollution according to claim 1 or the slow-release phosphorus removal agent for low-temperature water body phosphorus pollution prepared by the preparation method of claim 2, which can be applied to the removal of phosphorus pollution in low-temperature water bodies, is a hard white solid, insoluble in water, and sinks to the lower water phase after being put into the water body; through slow infiltration of water molecules, the nutrient substrates starch and inorganic salts are continuously released, realizing long-acting stimulation of the growth of polyphosphorus bacteria.

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