Method for denitrification and dephosphorization of water body and sediment remediation by coupling algae and bacteria

Abstract

This invention discloses a method for algae-bacteria coupled denitrification and phosphorus removal in water bodies and sediment remediation, belonging to the field of aquatic ecological restoration technology. The invention employs a method of immobilizing degummed silk fiber-pure cotton canvas-sodium alginate, forming a dual-algae system with *Chlorella vulgaris* in its logarithmic growth phase and suspended *Chlorella sorokinica* in its logarithmic growth phase. This system is combined with suspended denitrification and phosphorus removal bacteria to achieve a three-phase synergistic purification system under natural light and without aeration. A 60-day pilot-scale operation of this method showed a TN removal rate of 87.0%, a TP removal rate of 80.7%, and a sediment organic matter degradation rate of 55.2%. This invention is energy-free, low-carbon, ecologically safe, and has low operation and maintenance costs, making it suitable for in-situ remediation of eutrophic rivers, lakes, landscape water bodies, and aquaculture wastewater in still or slow-flowing water bodies.

Description

Technical Field

[0001] This invention relates to the field of aquatic ecological restoration technology, and in particular to a method for algae-bacteria coupled with water denitrification, phosphorus removal and bottom sediment restoration. Background Technology

[0002] With the acceleration of industrialization and urbanization, large amounts of nitrogen and phosphorus pollutants are discharged into rivers, lakes, and landscape water bodies, causing serious eutrophication and endogenous pollution of bottom sediments. Traditional water remediation methods are mainly divided into physical methods (dredging, aeration), chemical methods (flocculation and sedimentation), and biological methods (microbial agents, constructed wetlands). Among them, physical methods are energy-intensive and disturb the ecosystem; chemical methods are prone to secondary pollution; while biological methods are eco-friendly, existing algae-microbe coupling technologies still have many shortcomings.

[0003] Current reported algae-bacterial coupled remediation technologies mostly rely on mechanical aeration to maintain dissolved oxygen levels to meet the metabolic needs of aerobic microorganisms. However, forced aeration not only consumes a large amount of electricity and increases operation and maintenance costs, but also causes severe disturbance to the sediment, leading to the resuspension of pollutants in the sediment and reducing the purification effect. In addition, most technologies simply mix algae and bacterial agents and add them directly without precise control of the algae growth period, and the currently reported algae-bacterial coupled remediation technologies cannot simultaneously achieve the purification of overlying water and the control of endogenous pollution in the sediment under non-aeration conditions.

[0004] In terms of algal immobilization carriers, traditional methods often employ single sodium alginate encapsulation. While this material exhibits good biocompatibility, it suffers from low mechanical strength, poor mass transfer efficiency, easy algal cell detachment, and low light transmission efficiency, making it difficult to maintain structural integrity and algal activity in natural water bodies over the long term. Furthermore, existing technologies largely focus on nitrogen and phosphorus removal from the overlying water, neglecting the control of endogenous pollution in the sediment. Sediment, acting as a long-term "pollution reservoir," continuously releases nitrogen and phosphorus into the overlying water when the external environment changes, leading to repeated water quality deterioration. Currently, there is a lack of a green method that can simultaneously achieve nitrogen and phosphorus removal from the overlying water and in-situ remediation of the sediment without aeration or power generation.

[0005] Therefore, developing a low-energy-consumption, high-stability, mud-water synergistic remediation algae-bacteria coupling technology has significant engineering application value and environmental significance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for denitrification and phosphorus removal in water bodies and sediment remediation through a combination of algae and bacteria. This invention utilizes three core technologies: precise control of two algae during their logarithmic growth phase, enhanced photosynthetic oxygen production carrier using degummed silk fibers, and a three-phase synergistic approach involving self-oxygenation without aeration. This allows for simultaneous denitrification and phosphorus removal in overlying water and control of endogenous pollution in sediment under power-free and low-carbon conditions.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention provides a method for algae-bacteria coupled water denitrification and phosphorus removal with sediment remediation, comprising the following steps:

[0009] After immersing degummed silk fibers and pure cotton canvas in logarithmic growth phase Chlorella algae solution, cross-linking treatment was performed to obtain a degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier.

[0010] The process involves adding the aforementioned degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algal carrier, logarithmic growth phase suspended Chlorella vulgaris solution, and suspended denitrification and phosphorus removal functional bacteria to the water body to be restored before operation.

[0011] In this invention, Chlorella is used as an immobilized carrier algae species, which has the advantages of being resistant to adhesion and having stable oxygen production; Sorokin Chlorella is used as a suspended algae species, which has the advantages of rapid growth and high nitrogen and phosphorus absorption efficiency.

[0012] Optionally, the OD of the Chlorella algal solution... 680 The OD value of the suspended Chlorella vulgaris solution is 0.9-1.1. 680 It ranges from 0.9 to 1.1.

[0013] This invention will increase the OD of algae 680 The growth coefficient was precisely controlled between 0.9 and 1.1 (logarithmic growth phase), and the algal cell culture time was 4 days. Algal cell viability was ≥95%, and the proliferation rate was ≥0.3 days. -1 This invention strictly limits both algae to the logarithmic growth phase, relying on algal photosynthesis to autonomously produce oxygen and form an aerobic-facultative anaerobic gradient microenvironment, without the need for mechanical aeration.

[0014] This invention provides the first quantitative verification of the following mechanism of action of degummed silk fibers:

[0015] Light transmission: The β-fold structure of degummed silk fibers has a high refractive index, which can scatter and transmit light, increasing the light penetration depth by 35.2%; Oxygen transmission: The porous structure of degummed silk fibers provides diffusion channels for oxygen molecules, improving oxygen transmission efficiency by 38.7%; Algal activity: The active groups on the surface of degummed silk fibers promote the attachment and growth of algal cells, increasing the photosynthetic oxygen production rate of algal cells by 42.5%.

[0016] Optionally, the suspended nitrogen and phosphorus removal functional bacterial agent includes nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus; the effective viable count ratio of the nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus in the suspended nitrogen and phosphorus removal functional bacterial agent is 2:2:3:3.

[0017] Optionally, the pure cotton canvas is in the form of 10 cm × 10 cm squares; the concentration of Chlorella in the degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algae carrier is 2.5 × 10⁻⁶. 9 The density of suspended Chlorella cells / m² in the water after addition is 1.0 × 10⁻⁶ cells / m². 7 The dosage of the degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algae carrier was 20 pieces / mL. 3 The dosage of the suspended nitrogen and phosphorus removal functional bacterial agent is 500 g / mu.

[0018] Optionally, if the organic matter content of the bottom sediment of the water body to be repaired is ≤5% and the total phosphorus content is ≤800 mg / kg, the degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier and suspended Chlorella sologenophyllin solution are first added to the water body to be repaired simultaneously, and then suspended nitrogen and phosphorus removal functional bacteria are added at intervals of 24h-48h before operation;

[0019] If the organic matter content of the sediment in the water body to be repaired is >5% and the total phosphorus content is >800mg / kg, then first add suspended nitrogen and phosphorus removal bacteria to the water body to be repaired. After 24h-48h, simultaneously add the degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier and suspended Sorokin Chlorella algal solution before operation.

[0020] This invention allows for different remediation methods for different types of water bodies:

[0021] (1) Conventional water bodies (bottom sediment organic matter ≤5%, total phosphorus ≤800 mg / kg): First add the dual algae system, and then add suspended bacteria 24 h later. The algae first form an aerobic environment, which is conducive to the subsequent colonization of the bacterial community.

[0022] (2) Highly polluted bottom sediment water (bottom sediment organic matter >5%, total phosphorus >800 mg / kg): first add suspended bacteria, and then add a dual algae system 24 h later. The bacteria will degrade the bottom sediment organic matter first, creating favorable conditions for algae growth.

[0023] Optionally, the operating conditions are: pH 7.0-8.0, water temperature 20-30℃, water depth 0.5-1.5 m, natural light (light intensity 2000-6000 Lux), no aeration, natural reoxygenation.

[0024] This invention employs a non-aeration, self-oxygenating operation mechanism, which has the following advantages:

[0025] (1) Increase the oxygen production rate of photosynthesis in both fixed and suspended algae: 8.5-12.3 mg O2 / (L·h).

[0026] (2) Provide an aerobic-facultative microenvironment: DO 4-6 mg / L for the surface water (aerobic zone), DO 1-3 mg / L for the middle layer (facultative zone), and DO 0.2-0.5 mg / L for the bottom layer (anaerobic zone).

[0027] (3) Simultaneous nitrification and denitrification: NH4 in the aerobic zone + →NO3 - In the facultative oxygen region, NO3-→N2.

[0028] (4) Polyphosphate: Polyphosphate-accumulating bacteria in the aerobic zone absorb excessive amounts of phosphorus.

[0029] (5) Sediment remediation: Suspended bacteria penetrate the sediment, degrade organic matter, and passivate endogenous phosphorus.

[0030] Optionally, the method for preparing the degummed silk fiber includes the step of boiling the degummed silk fiber in 0.5% Na2CO3 solution for 30 minutes;

[0031] The amount of degummed silk fiber used is 15%-20% of the weight of the pure cotton canvas;

[0032] The crosslinking agent is 2.5 wt% calcium chloride.

[0033] More preferably, the water body includes eutrophic rivers, lakes, landscape water bodies, and aquaculture wastewater.

[0034] More preferably, the initial water quality of the water body is TN≤10 mg / L, TP≤1.5 mg / L, COD≤80 mg / L, and water depth≤2 m.

[0035] This invention provides a wastewater treatment system comprising a degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier, a suspended Sorokin Chlorella liquid, and a suspended nitrogen and phosphorus removal functional bacterial agent.

[0036] The wastewater treatment system provided by this invention is a three-phase synergistic purification system, which has the following advantages:

[0037] (1) Immobilized algal unit: Chlorella immobilization carrier, providing stable oxygen production and structural support.

[0038] (2) Suspended algae unit: Chlorella sorogenesis suspension, which rapidly absorbs nitrogen and phosphorus and improves the purification rate.

[0039] (3) Suspended bacteria unit: nitrogen and phosphorus removal compound functional bacteria, which penetrate the bottom sediment to degrade organic matter and passivate endogenous phosphorus.

[0040] Optionally, the preparation method of the degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier includes the step of immersing degummed silk fiber and pure cotton canvas in Chlorella algal solution and then performing cross-linking treatment to obtain the degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier.

[0041] The suspended nitrogen and phosphorus removal functional bacterial agent includes nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus; the effective viable count ratio of the nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus in the suspended nitrogen and phosphorus removal functional bacterial agent is 2:2:3:3.

[0042] More preferably, the wastewater includes eutrophic rivers, lakes, landscape water bodies, and aquaculture wastewater.

[0043] This invention provides the application of the above-mentioned wastewater treatment system in wastewater treatment.

[0044] More preferably, the wastewater includes eutrophic rivers, lakes, landscape water bodies, and aquaculture wastewater.

[0045] More preferably, the initial water quality of the wastewater is TN≤10 mg / L, TP≤1.5 mg / L, COD≤80 mg / L, and water depth≤2 m.

[0046] The present invention discloses the following technical effects:

[0047] This invention establishes for the first time a three-phase synergistic system of "immobilized logarithmic-phase algae + suspended logarithmic-phase algae + suspended bacteria": immobilized algae provide stable oxygen production and structural support, suspended algae rapidly absorb nitrogen and phosphorus, and suspended bacteria penetrate the sediment to degrade organic matter; the three are functionally complementary and metabolically coupled. This invention also achieves simultaneous sludge-water remediation under aeration-free conditions for the first time: relying on photosynthetic self-oxygenation to form an aerobic-facultative anaerobic gradient microenvironment, simultaneously completing nitrification and denitrification, phosphorus accumulation, and sediment organic matter mineralization. Furthermore, this invention quantitatively reveals for the first time the enhanced light conduction and oxygen transfer mechanism of degummed silk fibers: the microfiber structure of degummed silk fibers can scatter and conduct light, increasing light penetration depth by more than 35%; simultaneously, its porous structure provides diffusion channels for oxygen molecules, improving oxygen transfer efficiency by more than 38%.

[0048] The method provided by this invention requires no mechanical aeration, relying entirely on photosynthetic self-oxygenation (completely aeration-free, zero-power, low-carbon and environmentally friendly), with operation and maintenance costs only 5%-10% of traditional aeration technologies. The degummed silk fiber-reinforced carrier is recyclable and reusable, and the microbial agent does not require immobilization, making the process simple and easily engineered. A 60-day pilot-scale operation showed a TN removal rate of 87.0%, a TP removal rate of 80.7%, a sediment organic matter degradation rate of 55.2%, and a 72.3% reduction in total phosphorus release from the sediment. It is suitable for in-situ remediation of eutrophic rivers, lakes, landscape water bodies, and aquaculture wastewater in still or slow-flowing water bodies, possessing extremely high industrial application value and market prospects. Furthermore, the process of this invention is simple, easily engineered, and produces no secondary pollution; the carrier is recyclable and reusable, and the microbial agent does not require immobilization. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 Comparison of the performance of degummed silk fiber reinforced immobilization carriers;

[0051] Figure 2 The effect of different dosing sequences on purification effect;

[0052] Figure 3 A comparison of the purification effects of the dual-algae system and the single-algae system;

[0053] Figure 4 The impact of the presence or absence of degummed silk fibers on the purification effect;

[0054] Figure 5 The effect of different algal growth stages on purification efficiency;

[0055] Figure 6 The water quality change curves are from a 60-day pilot test run.

[0056] Figure 7 The effect of different dosing intervals on the purification effect. Detailed Implementation

[0057] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0058] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0059] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0060] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0061] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0062] Unless otherwise specified, all materials used in this invention are obtained through conventional purchase by those skilled in the art; all methods employed in this invention are methods well known to those skilled in the art.

[0063] Chlorella pyrenoidosa was purchased from the Freshwater Algae Collection of the National Aquatic Organism Germplasm Resource Bank, species number FACHB-415; Chlorella sorokiniana was purchased from the Freshwater Algae Collection of the National Aquatic Organism Germplasm Resource Bank, species number FACHB-24; Nitrifying bacteria (Nitrobacter) was purchased from Wuhan Kemic Biomedical Technology Co., Ltd., catalog number KMK-XH001, with an effective viable count ≥5.0×10⁻⁶. 9 CFU / g (5 billion CFU / g); denitrifying bacteria (Paracoccus denitrificans) were purchased from Ningbo Mingzhou Biotechnology Co., Ltd., product number B98086, with an effective viable count of ≥5.0×10⁻⁶. 9CFU / g (5 billion CFU / g); Acinetobacter was purchased from the China Industrial Microbial Culture Collection Center (CICC), catalog number CICC 20869, with an effective viable count of ≥2.0×10⁻⁶. 10 CFU / g (20 billion CFU / g); Bacillus subtilis was purchased from Guangzhou Boshan Biological Feed Co., Ltd., product number BS-001, with an effective viable count of ≥2.0×10⁻⁶. 10 CFU / g (20 billion CFU / g).

[0064] Suspended nitrogen and phosphorus removal functional bacterial agent: prepared by mixing nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria and Bacillus in an effective viable count ratio of 2:2:3:3.

[0065] Example 1: Preparation and performance testing of degummed silk fiber reinforced immobilization carrier

[0066] (a) Material preparation

[0067] Degummed silk fibers: Boil degummed silk fibers in 0.5% Na2CO3 solution for 30 minutes, wash and dry them, and control the length to 1-2cm.

[0068] Pure cotton canvas: Cut into 10 cm × 10 cm squares. Alkali washing step: Immerse the pure cotton canvas squares in a scouring solution containing 20-50 g / L NaOH and 2-3 g / L scouring agent (in this example, the concentration of NaOH in the scouring solution is 35 g / L and the concentration of scouring agent is 2.5 g / L), with a bath ratio of 1:20, at 95-100℃ for 60-90 min. After removal, wash repeatedly with deionized water until the pH of the washing solution is neutral, and dry at 60℃ for later use. Sterilization step: Wrap the alkali-washed pure cotton canvas squares in gauze, place them in an autoclave, sterilize at 121℃ for 20 min, remove, dry at 60℃, and place in a sterile container for later use.

[0069] Chlorella: Logarithmic growth phase (OD) 680 =1.02, cultured in BG11 medium at 28℃ for 4 days), algal cell viability was 96.5%.

[0070] Sodium alginate solution: 2.5 wt%, sterilized at 121℃ for 20 min.

[0071] Calcium chloride solution: 2.5 wt%, sterilized.

[0072] Chlorella-sodium alginate mixture: Mix 30 mL of Chlorella solution with 30 mL of 2.5 wt% sodium alginate.

[0073] (ii) Grouping of immobilized carriers

[0074] Control group 1 (canvas only): pure cotton canvas with sodium alginate encapsulation, i.e., pure cotton canvas immersed in the logarithmic growth phase (OD). 680 =1.02) The chlorella was fully adsorbed into a mixture of chlorella and sodium alginate, and then transferred to a 2.5 wt% calcium chloride solution for cross-linking and curing at 28°C for 75 min. The concentration of chlorella in this carrier was 2.5 × 10⁻⁶. 9 cells / m 2 (Based on canvas area);

[0075] Control group 2 (sodium alginate only): Sodium alginate only (no canvas, no silk), i.e. Chlorella-sodium alginate mixture;

[0076] Experimental group (silk + canvas): pure cotton canvas + 15% degummed silk fiber + sodium alginate encapsulation, that is, immersing the degummed silk fiber and pure cotton canvas in the logarithmic growth phase (OD). 680 =1.02) The chlorella-sodium alginate mixture was fully adsorbed, and the amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and cured at 28℃ for 75 min. The concentration of chlorella in this carrier was 2.5×10⁻⁶. 9 cells / m 2 (Based on canvas area).

[0077] (III) Carrier performance testing

[0078] Each group of immobilized carriers was removed, rinsed three times with sterile deionized water, and drained of surface moisture. The performance of the carriers under different treatments was then tested, and the results are shown in Table 1 and 2. Figure 1 As shown.

[0079] Table 1. Carrier performance test results

[0080] Mechanical strength (N) 12.3 ± 1.2 4.5 ± 0.6 18.5 ± 1.5 <![CDATA[Algal cell fixation amount (×10 9 cells / m 2 )]]> 2.1 ± 0.2 1.5 ± 0.2 3.2 ± 0.3 Light penetration depth (cm) 15.2 ± 1.5 12.5 ± 1.2 20.8 ± 1.8 Oxygen transfer efficiency (%) 52.3 ± 3.5 45.6 ± 3.0 72.5 ± 4.2 Algal cell survival rate (%) after 60 days 72.5 ± 4.0 58.3 ± 5.0 88.2 ± 3.5

[0081] The results showed that compared with control group 1, the experimental group exhibited a 50.4% increase in mechanical strength, a 52.4% increase in algal cell fixation, a 36.8% increase in light penetration depth, a 38.7% increase in oxygen transfer efficiency, and a 21.6% increase in 60-day survival rate. Compared with control group 2, the experimental group showed a 311.1% increase in mechanical strength, a 113.3% increase in algal cell fixation, a 66.4% increase in light penetration depth, a 59.0% increase in oxygen transfer efficiency, and a 51.3% increase in 60-day survival rate. Therefore, the experimental group (degummed silk fiber + canvas) was significantly superior to the control group in terms of mechanical strength, algal cell fixation, light penetration depth, oxygen transfer efficiency, and 60-day survival rate (p<0.01), demonstrating the reinforcing effect of degummed silk fiber.

[0082] The above data show that: the material structure of the embodiment is extremely robust, with significantly enhanced resistance to wear and impact, providing a solid structural foundation for long-term operation; the material of the experimental group has excellent affinity and fixation effect on algae, meaning that higher bioreactor capacity can be obtained in the same area; the material of the experimental group has better light transmittance or structural porosity, making it easier for light energy to be transmitted to the deep algal layer, ensuring the photosynthetic efficiency of deep cells; the material of the experimental group can effectively alleviate oxygen limitation and promote cell growth and metabolite synthesis; the material of the experimental group can maintain stable activity under long-term operation, significantly reducing maintenance costs and replacement frequency, demonstrating the engineering application potential of this technology.

[0083] Example 2: Experiment on Precise Determination of Logarithmic Growth Phase of Algae

[0084] Chlorella algae solution (concentration of OD) 680 = 2.0 ± 0.1) and Sorokin Chlorella algal solution (concentration of OD) 680 =2.0 ± 0.1) were inoculated into BG11 medium at an inoculum of 10%, and cultured under the following conditions: 25°C, 4000 Lux, and a light-dark ratio of 12:12 (i.e., 12 hours of light and 12 hours of darkness). OD was measured daily. 680 The results of the algal cell viability test are shown in Table 2.

[0085] Table 2. OD of algae at different time points 680 Test results

[0086] 0 <![CDATA[OD 680 =0.15, vitality 92% <![CDATA[OD 680 =0.18, vitality 91% 1 <![CDATA[OD 680 =0.32, vitality 94% <![CDATA[OD 680 =0.38, vitality 93% 2 <![CDATA[OD 680 =0.58, vitality 95% <![CDATA[OD 680 =0.65, vitality 94% 3 <![CDATA[OD 680 =0.85, vitality 96% <![CDATA[OD 680 =0.92, vitality 95% 4 <![CDATA[OD 680 =1.02, Vitality 96.5% <![CDATA[OD 680 =1.08, vitality 96% 5 <![CDATA[OD 680 =1.15, vitality 93% <![CDATA[OD 680 =1.22, vitality 92% 6 <![CDATA[OD 680 =1.22, Vitality 88% <![CDATA[OD 680 =1.28, vitality 87% 7 <![CDATA[OD 680 =1.25, Vitality 82% <![CDATA[OD 680 =1.30, Vitality 80%

[0087] The results showed that the optimal logarithmic growth phase was on day 4 after inoculation, and OD... 680 =1.0-1.1, and algal cell viability ≥95%.

[0088] Example 3: The effect of different addition sequences on purification effect (pilot-scale)

[0089] Three pilot-scale reactors (1 m³ in volume) were set up. 3 The initial water quality was TN=8.5 mg / L, TP=1.2 mg / L, bottom sediment organic matter 6.2%, and total phosphorus content 873 mg / kg, with a water depth of 1 m. Different dosing sequences were compared. Operating conditions were: pH 7.0~8.0, water temperature 20~30℃, water depth 1 m, natural light (light intensity 4000~5000 Lux), no aeration, and natural reoxygenation (dissolved oxygen was maintained by natural reoxygenation and algal photosynthetic oxygen production).

[0090] The immobilized algal carriers for all three schemes were prepared according to the method in Example 1: 10 cm × 10 cm pure cotton canvas blocks and degummed silk fibers (15% of the canvas mass) were immersed in a Chlorella-sodium alginate mixture (30 mL OD). 680 The algae solution (1.02 mL of algae solution + 30 mL of 2.5 wt% sodium alginate) is fully adsorbed, then transferred to a 2.5 wt% calcium chloride solution and cross-linked and cured at 25°C for 75 min. After rinsing three times with sterile deionized water, it is ready for use.

[0091] The effective viable count ratio of nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus in the suspended denitrification and phosphorus removal functional bacterial agent is 2:2:3:3.

[0092] The specific steps of Plan A are: algae first, then bacteria, that is, first add degummed silk fiber-pure cotton canvas-sodium alginate to embed and immobilize Chlorella carriers (20 pieces / m²). 3 Chlorella dosage: 2.5 × 10 9 cells / m 2 ) and suspended Sorokin Chlorella algal solution (OD) 680 =1.08, dosage is 1.0×10 7 (cells / mL water body), and 24 h later, add suspended nitrogen and phosphorus removal functional bacteria (dosage: 500 g / mu, i.e., 0.75 g / m³). 3 ).

[0093] The specific steps of Plan B are: bacteria first, then algae, that is, first add suspended nitrogen and phosphorus removal functional bacteria (dosage is 500g / mu, i.e. 0.75 g / m²). 3 ), and 24 hours later, simultaneously add degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized Chlorella carrier (20 pieces / m³). 3 The concentration of Chlorella in this carrier was 2.5 × 10⁻⁶. 9 cells / m 2 ) and suspended Sorokin Chlorella algal solution (OD) 680 =1.08, dosage is 1.0×10 7 (cells / mL water).

[0094] The specific steps of scheme C are as follows: Simultaneous addition of two algae and bacteria, namely, simultaneous addition of degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized Chlorella carrier (20 pieces / m²). 3 The concentration of Chlorella in this carrier was 2.5 × 10⁻⁶. 9 cells / m 2 ), Suspended Sorokin Chlorella algal solution (OD) 680 =1.08, dosage is 1.0×10 7(cells / mL water) and suspended nitrogen and phosphorus removal functional bacteria (dosage: 500 g / mu, i.e., 0.75 g / m³). 3 ).

[0095] After running for 30 days, the results are shown in Table 3 and Figure 2 As shown.

[0096] Table 3. Results of Repair Effect Testing

[0097] TN removal rate (%) 75.2 ± 3.5 82.5 ± 3.2 68.5 ± 4.0 TP removal rate (%) 70.5 ± 3.8 78.3 ± 3.5 65.2 ± 4.2 <![CDATA[NH4 + -N removal rate (%) 85.2 ± 3.0 91.2 ± 2.8 78.5 ± 3.5 Sediment organic matter degradation rate (%) 38.5 ± 3.2 45.6 ± 3.0 32.5 ± 3.5 Reduction rate of total phosphorus release from sediment (%) 65.2 ± 4.0 72.3 ± 3.8 58.5 ± 4.5

[0098] The results showed that for highly polluted sediment water (organic matter > 5%), adding bacteria first and then algae (Scheme B) resulted in the addition of TN, TP, and NH4. + The -N removal rate and sediment remediation effect were significantly better than other sequences (p<0.05). Therefore, for highly polluted sediment water, adding bacteria first and then algae (Scheme B) has the best purification effect.

[0099] Example 4: Comparison of purification effects between dual-algae system and single-algae system

[0100] (a) Material preparation

[0101] Same as Example 1.

[0102] (II) Grouping

[0103] Three pilot-scale reactors were set up (with the same water quality as in Example 3), and the reactors were divided into groups:

[0104] Group 1 (Dual Algae + Bacteria): Degummed silk fibers and pure cotton canvas were immersed in the logarithmic growth phase (OD). 680 =1.02) The algae were fully adsorbed in a mixture of Chlorella and sodium alginate. The amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and curing at 28℃ for 75 min to obtain a degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algae carrier. The concentration of Chlorella in this carrier was 2.5×10⁻⁶. 9 cells / m 2 Simultaneously add 20 pieces of degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated immobilized algae carriers and algae in the logarithmic growth phase (OD) to the water to be remediated. 680 The suspended Chlorella decomposition solution (=1.08) resulted in an initial suspended Chlorella decomposition density of 1.0 × 10⁸ in the water. 7 cells / mL; 24 hours later, add suspended nitrogen and phosphorus removal functional bacteria to the water body. The dosage of the suspended nitrogen and phosphorus removal functional bacteria is 500 g / mu (effective viable bacteria count ≥10). 9 CFU / g);

[0105] Group 2 (fixed algae + bacteria only): Degummed silk fibers and pure cotton canvas were immersed in the logarithmic growth phase (OD). 680 =1.02) The algae were fully adsorbed in a mixture of Chlorella and sodium alginate. The amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and curing at 28℃ for 75 min to obtain a degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algae carrier. The concentration of Chlorella in this carrier was 2.5×10⁻⁶. 9 cells / m 2 Add 20 pieces of degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algae carrier to the water to be remediated; 24 hours later, add suspended nitrogen and phosphorus removal functional bacteria to the water at a dosage of 500 g / mu (effective viable bacteria count ≥10). 9 CFU / g);

[0106] Group 3 (suspended algae + bacteria only): Added to the water to be remediated during the logarithmic growth phase (OD). 680 The suspended Chlorella vulgaris solution (=1.02) was added, and the initial suspended Chlorella vulgaris density in the water was 1.0 × 10⁻⁶. 7 cells / mL; 24 hours later, add suspended nitrogen and phosphorus removal functional bacteria to the water body. The dosage of the suspended nitrogen and phosphorus removal functional bacteria is 500 g / mu (effective viable bacteria count ≥10). 9 CFU / g).

[0107] After 45 days of operation, the following tests were conducted: pH 7.0-8.0, water temperature 20-30℃, water depth 1 m, natural light (light intensity 4000-5000 Lux), no aeration, and natural reoxygenation. The test results are shown in Table 4. Figure 3 As shown.

[0108] Table 4 Results of Repair Effect Testing

[0109] TN removal rate (%) 82.5 ± 3.2 58.3 ± 4.0 65.2 ± 3.8 TP removal rate (%) 78.3 ± 3.5 52.5 ± 4.2 60.5 ± 4.0 Dissolved oxygen (mg / L) 5.2 ± 0.5 3.2 ± 0.4 4.5 ± 0.5 Oxygen production duration (h / d) 12.5 8.5 10.2 System stability excellent Poor (algae shedding) (Algal suspension fluctuation)

[0110] The results showed that the TN and TP removal rates and dissolved oxygen levels in group 1 were significantly better than those in the single algae system (p<0.01), demonstrating the synergistic effect of the two algae. In this system, fixed algae provide stable oxygen production, while suspended algae enhance the purification rate.

[0111] Example 5: The effect of the presence or absence of degummed silk fibers on the purification effect

[0112] (a) Material preparation

[0113] Same as Example 1.

[0114] (II) Grouping

[0115] Two pilot-scale reactors were set up (with the same water quality as in Example 3), and the reactors were divided into groups:

[0116] Group A (containing silk): Same as Group 1 in Example 3;

[0117] Group B (no silk): Add suspended nitrogen and phosphorus removal functional bacteria to the water body at a dosage of 500 g / mu (effective viable bacteria count ≥10). 9 CFU / g); 24 hours later, 20 pieces of embedded Chlorella vulgaris (in the logarithmic growth phase (OD)) were simultaneously added to the water to be remediated. 680 =1.02) Chlorella (the concentration of Chlorella on the canvas is 2.5×10) 9 cells / m 2 ) and in the logarithmic growth phase (OD) 680 The suspended Chlorella vulgaris solution (=1.02) was added, and the initial suspended Chlorella vulgaris density in the water was 1.0 × 10⁻⁶. 7 cells / mL; measured after 45 days of operation. Operating conditions were: pH 7.0-8.0, water temperature 20-30℃, water depth 1 m, natural light (light intensity 4000-5000 Lux), no aeration, natural reoxygenation. Results are shown in Table 5. Figure 4 As shown.

[0118] Table 5. Results of purification effect test

[0119] TN removal rate (%) 82.5 ± 3.2 62.5 ± 4.0 TP removal rate (%) 78.3 ± 3.5 58.2 ± 4.2 Dissolved oxygen (mg / L) 5.2 ± 0.5 3.5 ± 0.4 Carrier integrity Excellent (no damage) Poor (30% damaged) Algal cell survival rate (%) 88.2 ± 3.5 58.3 ± 5.0

[0120] The results showed that the degummed silk fiber reinforced carrier increased the removal rates of TN and TP by 20% and 20.1%, respectively, increased dissolved oxygen by 48.6%, and increased algal cell survival rate by 51.2%, demonstrating that the degummed silk fiber reinforced carrier significantly improved purification efficiency and system stability, and that the degummed silk fiber played a key role.

[0121] Example 6: Effect of different algal growth stages on purification effect

[0122] Three pilot-scale reactors were set up (with the same water quality as in Example 3), and immobilized Chlorella proteoglycans and suspended Chlorella sologenosum were used at different growth stages:

[0123] Group 1: Both algae are in the logarithmic growth phase (OD). 680 =1.02, cultured for 4 days), the specific steps are: immerse degummed silk fibers and pure cotton canvas in the logarithmic growth phase (OD). 680=1.02) The algae were fully adsorbed in a mixture of Chlorella and sodium alginate. The amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and curing at 28℃ for 75 min to obtain a degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algae carrier. The concentration of Chlorella in this carrier was 2.5×10⁻⁶. 9 cells / m²; Add suspended nitrogen and phosphorus removal functional bacteria to the water body. The dosage of the suspended nitrogen and phosphorus removal functional bacteria is 500g / mu (effective viable bacteria count ≥10). 9 CFU / g); 24 hours later, 20 pieces of degummed silk fiber-pure cotton canvas-sodium alginate-embedded and immobilized algal carriers and algae in the logarithmic growth phase (OD) were simultaneously added to the water to be remediated. 680 The suspended Chlorella vulgaris solution (=1.02) was added, and the initial suspended Chlorella vulgaris density in the water was 1.0 × 10⁻⁶. 7 cells / mL;

[0124] Group 2: Both algae were in the early logarithmic growth phase (OD). 680 =0.5, cultured for 2 days), degummed silk fibers and pure cotton canvas were immersed in the logarithmic growth phase (OD). 680 =0.5) Chlorella-sodium alginate mixture was fully adsorbed, and the amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and cured at 28℃ for 75 min to obtain a degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algae carrier. The concentration of Chlorella in this carrier was 2.5×10 9 cells / m²; Add suspended nitrogen and phosphorus removal functional bacteria to the water body at a dosage of 500 g / mu (effective viable bacteria count ≥10). 9 CFU / g); 24 hours later, 20 pieces of degummed silk fiber-pure cotton canvas-sodium alginate-embedded and immobilized algal carriers and algae in the logarithmic growth phase (OD) were simultaneously added to the water to be remediated. 680 The suspended Chlorella vulgaris solution (=0.5) was added, and the initial suspended Chlorella vulgaris density in the water was 1.0 × 10⁻⁵. 7 cells / mL;

[0125] Group 3: Both algae were in the stationary phase (OD). 680 =1.5, cultured for 7 days), degummed silk fibers and pure cotton canvas were immersed in the logarithmic growth phase (OD). 680=1.5) Chlorella-sodium alginate mixture was fully adsorbed, and the amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and cured at 28℃ for 75 min to obtain a degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algae carrier. The concentration of Chlorella in this carrier was 2.5×10 9 cells / m²; Add suspended nitrogen and phosphorus removal functional bacteria to the water body at a dosage of 500 g / mu (effective viable bacteria count ≥10). 9 CFU / g); 24 hours later, 20 pieces of degummed silk fiber-pure cotton canvas-sodium alginate-embedded and immobilized algal carriers and algae in the logarithmic growth phase (OD) were simultaneously added to the water to be remediated. 680 The suspended Chlorella vulgaris solution (=1.5) was added, and the initial suspended Chlorella vulgaris density in the water was 1.0 × 10⁻⁶. 7 cells / mL.

[0126] After 30 days of operation, the following tests were conducted: pH 7.0-8.0, water temperature 20-30℃, water depth 1 m, natural light (light intensity 4000-5000 Lux), no aeration, and natural reoxygenation. The test results are shown in Table 6. Figure 5 As shown.

[0127] Table 6 Test Results

[0128] TN removal rate (%) 82.5 ± 3.2 65.2 ± 3.8 58.5 ± 4.0 TP removal rate (%) 78.3 ± 3.5 62.5 ± 4.0 55.2 ± 4.2 <![CDATA[Oxygen production rate (mg O2 / L·h)]]> 10.5 ± 0.8 6.2 ± 0.6 4.5 ± 0.5 Algal cell viability (%) 96.5 ± 2.0 88.5 ± 3.0 75.2 ± 4.0

[0129] The results showed that the TN and TP removal rates and oxygen production rates of algae in the logarithmic growth phase were significantly better than those of algae in the early exponential and stationary phases (p<0.01), demonstrating the importance of precise control of the growth phase. This data proves that algae in the logarithmic growth phase have the best purification effect.

[0130] Example 7: Results of a 60-day pilot run

[0131] The method employed was to use a combination of two algae in the logarithmic growth phase, degummed silk fiber carrier, and a process of adding bacteria before algae (immersing degummed silk fiber and pure cotton canvas in the substrate during the logarithmic growth phase). 680 =1.02) The algae were fully adsorbed in a mixture of Chlorella and sodium alginate. The amount of degummed silk fiber was 15% of the mass of pure cotton canvas. Then, it was transferred into a 2.5wt% calcium chloride solution for cross-linking and curing at 28℃ for 75 min to obtain a degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algae carrier. The concentration of Chlorella in this carrier was 2.5×10⁻⁶. 9 cells / m²; Add suspended nitrogen and phosphorus removal functional bacteria to the water to be remediated. The dosage of the suspended nitrogen and phosphorus removal functional bacteria is 500 g / mu (effective viable count ≥10). 9(CFU / g), 24 hours later, 20 pieces of degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carriers and algae in the logarithmic growth phase (OD) were simultaneously added to the water. 680 The suspended Chlorella vulgaris solution (=1.02) was added, and the initial suspended Chlorella vulgaris density in the water was 1.0 × 10⁻⁶. 7 A eutrophic landscape water body (area 50 m², water depth 1.2 m, initial TN=9.2 mg / L, TP=1.35 mg / L, COD=65 mg / L, bottom sediment organic matter 5.8%, total phosphorus content 893 mg / kg) was treated with cells / mL.

[0132] After 60 days of operation, the following tests were conducted. The operating conditions were: pH 7.0-8.0, water temperature 20-30℃, water depth 1.2 m, natural light (light intensity 4000-5000 Lux), no aeration, and natural reoxygenation. Samples were taken and tested every 10 days. The test results are shown in Table 7.

[0133] Table 7 Test Results

[0134] 0 9.2 1.35 65 1.2 5.8 10 5.8 0.85 48 3.5 5.2 20 3.2 0.55 35 4.8 4.5 30 2.0 0.38 28 5.2 3.8 40 1.5 0.30 24 5.5 3.2 50 1.3 0.28 22 5.6 2.9 60 1.2 0.26 21 5.8 2.6

[0135] The results showed that after 60 days of operation, TN decreased from 9.2 mg / L to 1.2 mg / L (removal rate 87.0%), TP decreased from 1.35 mg / L to 0.26 mg / L (removal rate 80.7%), COD decreased from 65 mg / L to 21 mg / L (removal rate 67.7%), DO increased from 1.2 mg / L to 5.8 mg / L, and sediment organic matter decreased from 5.8% to 2.6% (degradation rate 55.2%).

[0136] Comparative Example 1 (Undegummed silk fiber carrier)

[0137] The immobilization carrier was made of ordinary sodium alginate (without silk, only canvas, i.e., Group B treatment in Example 5), and the rest was the same as in Example 7.

[0138] Results: TN removal rate was 62.5%, TP removal rate was 58.2%, sediment organic matter degradation rate was 32.5%, and carrier damage was 30%.

[0139] Comparative Example 2 (Single Algae System)

[0140] Only immobilized Chlorella proteoglycans (without suspended Chlorella sorokin, i.e., group 2 treatment of Example 4) were used, and the rest was the same as in Example 7.

[0141] Results: TN removal rate was 58.3%, TP removal rate was 52.5%, oxygen production rate was 3.2 mg O2 / L·h, and system stability was poor.

[0142] Comparative Example 3 (non-logarithmic growth phase algae)

[0143] Both algae are in the stationary phase (OD). 680 =1.5, cultured for 7 days (i.e., group 3 treatment in Example 6), the rest is the same as in Example 7.

[0144] Results: TN removal rate was 58.5%, TP removal rate was 55.2%, oxygen production rate was 4.5 mg O2 / L·h, and algal cell viability was 75%.

[0145] Comparative Example 4 (Algae were added first, followed by bacteria, to highly polluted sediment)

[0146] The treatment adopted the method of adding two algae first and then bacteria after 24 hours (instead of bacteria first and then algae, i.e., treatment A of Example 3). The bottom sediment had 5.8% organic matter and 907 mg / kg total phosphorus content, and the rest was the same as in Example 7.

[0147] Results: TN removal rate was 75.2%, TP removal rate was 70.5%, and sediment organic matter degradation rate was 38.5%, which were lower than those of the present invention (82.5% / 78.3% / 45.6%).

[0148] Comparative Example 5 (no suspended bacteria)

[0149] Only two algae were added, without adding suspended nitrogen and phosphorus removal bacteria; otherwise, the process was the same as in Example 7.

[0150] Results: TN removal rate was 65.2%, TP removal rate was 58.5%, sediment organic matter degradation rate was 18.5%, and endogenous phosphorus control in sediment was poor.

[0151] Comparative Example 6 (Mechanical aeration replacing photosynthetic oxygen production)

[0152] Mechanical aeration was used to maintain DO ≥ 4 mg / L, and the rest was the same as in Example 7.

[0153] Results: TN removal rate was 85.2%, TP removal rate was 80.5%, but energy consumption was 0.8 kWh / m³. 3 The maintenance cost is 10 times that of this invention, and the disturbance of the bottom sediment leads to an increase in turbidity in the initial stage.

[0154] Example 8 (Different dosing time intervals)

[0155] Different addition time intervals were set: the processing method was the same as that of Group 1 in Example 6, the only difference being the addition time: simultaneous addition, 12-hour interval, 24-hour interval, 48-hour interval, and 72-hour interval; the rest was the same as in Example 7. The results are shown in Table 8 and... Figure 7 As shown.

[0156] Table 8 Test Results

[0157] at the same time 68.5 65.2 32.5 12h 75.2 72.5 38.5 24h 82.5 78.3 45.6 48h 78.5 75.2 42.5 72h 72.5 68.5 38.2

[0158] The results showed that when the dosing interval was 24 h, the removal rates of TN and TP and the degradation rate of organic matter in the sediment all reached their peak values ​​of 82.5%, 78.3%, and 45.6%, respectively, proving that 24 h was the optimal dosing interval.

[0159] Example 9: Application Effects on Different Water Body Types

[0160] The method of group 1 in Example 6 was applied to three different types of water bodies:

[0161] Water body A: Eutrophic river channel (initial TN=8.5 mg / L, TP=1.2 mg / L, bottom sediment organic matter 4.6%, total phosphorus content 621 mg / kg)

[0162] Water body B: Aquaculture wastewater (initial TN=12.5 mg / L, TP=2.8 mg / L, bottom sediment organic matter 4.3%, total phosphorus content 779 mg / kg)

[0163] Water body C: Landscape lake (initial TN=6.5 mg / L, TP=0.8 mg / L, bottom sediment organic matter 4.2%, total phosphorus content 533 mg / kg)

[0164] After 45 days of operation, the following tests were conducted. The operating conditions were: pH 7.0-8.0, water temperature 20-30℃, water depth 1 m, natural light (light intensity 4000-5000 Lux), no aeration, and natural reoxygenation. The test results are shown in Table 9.

[0165] Table 9 Test Results

[0166] Eutrophic waterways 82.5 ± 3.2 78.3 ± 3.5 45.6 ± 3.0 Aquaculture wastewater 78.5 ± 3.5 75.2 ± 3.8 42.5 ± 3.2 Landscape Lakes 85.2 ± 3.0 80.5 ± 3.2 48.2 ± 2.8

[0167] The results show that the method of the present invention is applicable to a variety of eutrophic water bodies and has a stable purification effect.

[0168] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for algae-bacteria coupled water denitrification and phosphorus removal with sediment remediation, characterized in that, Includes the following steps: After immersing degummed silk fibers and pure cotton canvas in Chlorella algae solution, cross-linking treatment was carried out to obtain a degummed silk fiber-pure cotton canvas-sodium alginate-embedded and immobilized algae carrier. The process involves adding the aforementioned degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algal carrier, suspended Chlorella salina algal solution, and suspended denitrification and phosphorus removal functional bacteria to the water body to be restored before operation.

2. The method according to claim 1, characterized in that, The OD of the Chlorella algae solution 680 The OD value of the suspended Chlorella vulgaris solution is 0.9-1.

1. 680 It ranges from 0.9 to 1.

1.

3. The method according to claim 1, characterized in that, The suspended nitrogen and phosphorus removal functional bacterial agent includes nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus; the effective viable count ratio of the nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus in the suspended nitrogen and phosphorus removal functional bacterial agent is 2:2:3:

3.

4. The method according to claim 1, characterized in that, The pure cotton canvas is in the form of 10 cm × 10 cm squares; the concentration of Chlorella in the degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algae carrier is 2.5 × 10⁻⁶. 9 The density of suspended Chlorella cells / m² in the water after addition is 1.0 × 10⁻⁶ cells / m². 7 The dosage of the degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated algae carrier was 20 pieces / mL. 3 The dosage of the suspended nitrogen and phosphorus removal functional bacterial agent is 500 g / mu.

5. The method according to claim 1, characterized in that, If the organic matter content of the bottom sediment of the water body to be repaired is ≤5% and the total phosphorus content is ≤800 mg / kg, the degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier and suspended Chlorella sologenophyllin solution are added to the water body to be repaired simultaneously. Suspended denitrification and phosphorus removal functional bacteria are added at intervals of 24h-48h before operation. If the organic matter content of the sediment in the water body to be repaired is >5% and the total phosphorus content is >800mg / kg, then first add suspended nitrogen and phosphorus removal bacteria to the water body to be repaired. After 24h-48h, simultaneously add the degummed silk fiber-pure cotton canvas-sodium alginate-embedded immobilized algal carrier and suspended Sorokin Chlorella algal solution before operation.

6. The method according to claim 1, characterized in that, The operating conditions are: pH 7.0-8.0, water temperature 20-30℃, water depth 0.5-1.5 m, natural light, no aeration, natural reoxygenation.

7. The method according to claim 1, characterized in that, The method for preparing the degummed silk fiber includes the step of boiling the degummed silk fiber in 0.5% Na2CO3 solution for 30 minutes; The amount of degummed silk fiber used is 15%-20% of the weight of the pure cotton canvas; The crosslinking agent is 2.5 wt% calcium chloride.

8. A wastewater treatment system, characterized in that, It includes degummed silk fiber-pure cotton canvas-sodium alginate-encapsulated immobilized algal carrier, suspended Sorokin Chlorella liquid, and suspended denitrification and phosphorus removal functional bacteria.

9. The wastewater treatment system according to claim 8, characterized in that, The preparation method of the degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algal carrier includes the steps of immersing degummed silk fiber and pure cotton canvas in Chlorella algal solution and then performing cross-linking treatment to obtain the degummed silk fiber-pure cotton canvas-sodium alginate embedded immobilized algal carrier. The suspended nitrogen and phosphorus removal functional bacterial agent includes nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus; the effective viable count ratio of the nitrifying bacteria, denitrifying bacteria, polyphosphate-accumulating bacteria, and Bacillus in the suspended nitrogen and phosphorus removal functional bacterial agent is 2:2:3:

3.

10. The application of the wastewater treatment system according to claim 8 or 9 in the treatment of wastewater.

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