Arsenic pollution efficient remediation method based on chlorella vulgaris-vallisneria co-symbiotic system

Abstract

The application discloses an efficient arsenic pollution remediation method based on a Chlorella vulgaris-Vallisneria natans symbiotic system and belongs to the technical field of pollution prevention and control. The remediation method uses Chlorella vulgaris as a functional algae species, and constructs a stable biofilm symbiotic system with Vallisneria natans. The Chlorella vulgaris is colonized on the surface of the Vallisneria natans in a dense biofilm, and the enrichment capacity of the Vallisneria natans for arsenic is improved through the effects of interface functional group amplification, rhizosphere arsenic form activation, photosynthetic protection and antioxidant regulation, and the stress resistance of the Vallisneria natans is greatly enhanced, so that efficient, rapid and ecologically friendly remediation of an arsenic-polluted water body is realized.

Description

Technical Field

[0001] This invention relates to the fields of pollution prevention and control, water environment pollution treatment and ecological restoration technology, and to a highly efficient method for the remediation of arsenic pollution based on a common Chlorella-Vallisneria salina symbiotic system, specifically to a highly efficient method for the remediation of arsenic-polluted water bodies based on the enhancement of arsenic enrichment and stress resistance of Vallisneria salina by common Chlorella. Background Technology

[0002] Arsenic is a highly toxic metallic pollutant that is widely present in the aquatic environment. Long-term exposure can cause skin lesions, cardiovascular diseases and various cancers in humans. It has been listed by the World Health Organization as a primary pollutant to be controlled.

[0003] Existing physical and chemical methods for remediating arsenic-contaminated water bodies suffer from drawbacks such as high costs, potential for secondary pollution, and disruption of the aquatic ecosystem. Submerged plant remediation, due to its environmental friendliness, low cost, and ecological value-added functions, has become a core direction for the green treatment of arsenic pollution. (Vallisneria natans...) Vallisneria natans As a typical perennial submerged plant, it has a large biomass, strong environmental adaptability, and a certain tolerance and accumulation capacity for arsenic, making it an excellent material for the remediation of arsenic pollution in water bodies.

[0004] However, the remediation of arsenic by using only Vallisneria natans faces significant technical bottlenecks: the arsenic enrichment efficiency is limited, and the enrichment amount is difficult to increase under high concentrations of arsenic stress; arsenic stress inhibits the growth of Vallisneria natans, leading to stagnation in plant height and biomass growth; arsenic can damage the photosynthetic system of Vallisneria natans, causing chlorophyll degradation and a decrease in photosynthetic efficiency; arsenic-induced oxidative stress can cause cell membrane lipid peroxidation and damage to the antioxidant system; and there are insufficient arsenic binding sites on the surface of Vallisneria natans, resulting in weak interfacial adsorption and fixation capacity.

[0005] Existing research largely focuses on submerged plant configurations or single-plant remediation. For example, CN108383243B discloses the enrichment of heavy metals using a combination of *Vallisneria natans*, *Ceratophyllum demersum*, and *Myriophyllum spicatum*; CN108101328B discloses the removal of heavy metals from sediment using submerged plants; and CN119558714A only lists *Vallisneria natans* and *Chlorella vulgaris* as species for toxicity testing. None of the above existing technologies disclose *Chlorella vulgaris*. The specific biofilm symbiotic system of Vallisneria natans did not reveal the mechanism by which biofilm-mediated interfacial functional group regulation, arsenic speciation activation, and physiological stress resistance synergistically enhance arsenic accumulation, thus failing to achieve efficient and rapid remediation of water bodies polluted with medium to high concentrations of arsenic.

[0006] Therefore, developing a highly efficient remediation method for arsenic pollution based on the common Chlorella-Vallisneria symbiotic system is of great practical significance for achieving low-cost and eco-friendly treatment of water bodies with high concentrations of arsenic pollution. Summary of the Invention

[0007] To address the problems of poor rhizome accumulation stability, large long-term fluctuations in effectiveness, and weak adaptability to natural environments in existing methods of remediating arsenic-contaminated waters using only *Vallisneria natans*, this invention provides a highly efficient method for remediating arsenic pollution based on a *Chlorella vulgaris*-*Vallisneria natans* symbiotic system. This method significantly enhances the arsenic accumulation capacity of *Vallisneria natans* and alleviates arsenic stress damage, while the *Chlorella vulgaris*-*Vallisneria natans* symbiotic system demonstrates high efficiency and stability in remediation. This invention uses *Chlorella vulgaris* as the functional algae species, constructing a stable biofilm symbiotic system with *Vallisneria natans*. *Chlorella vulgaris* colonizes the surface of *Vallisneria natans* via a dense biofilm, enhancing the arsenic accumulation capacity of *Vallisneria natans* through interfacial functional group amplification, rhizosphere arsenic speciation activation, photosynthetic protection, and antioxidant regulation, while also significantly strengthening the stress resistance of *Vallisneria natans*, achieving efficient, rapid, and eco-friendly remediation of arsenic-contaminated waters.

[0008] Firstly, a highly efficient method for remediating arsenic pollution is provided, including: S1: Vallisneria natans was planted in the remediation water system after adaptive cultivation; S2: Inoculate the expanded Chlorella vulgaris into the remediation water system to construct a Chlorella vulgaris-Vallisneria natans symbiotic system; S3: Continuous repair, including re-inoculation with common Chlorella and harvesting senescent plants to complete the repair.

[0009] In some embodiments, in S1, adaptive cultivation refers to selecting Vallisneria natans with a plant height of 25-35cm, adapting them to hydroponics in Hogrange nutrient solution for 15 days, and then transplanting them into the restoration water system for planting, preferably at a height of 30cm.

[0010] In some embodiments, after planting Vallisneria natans in S1, modified Hogland nutrient solution is added for cultivation.

[0011] In some embodiments, the hydroponic culture is adapted to a culture temperature of 28~33 ℃, a pH stable at 6.1~6.5, a daily full-spectrum light duration of ≥8 h, and regular aeration every day.

[0012] In some embodiments, in S1, Vallisneria natans is planted at a density of 30 to 60 plants per cubic meter of the remediation water system, preferably 30, 40, 50, or 60 plants.

[0013] In some embodiments, in S2, common Chlorella is inoculated at 2-8% (v / v) of the total volume of the remediation water system, preferably 2%, 3%, 4%, 5%, 6%, 7%, or 8%.

[0014] In some embodiments, the common Chlorella is expanded using BG-11 medium and cultured to the logarithmic growth phase under conditions of 23±0.5 ℃, light intensity of 3960 lux, and light-dark cycle of 12 h:12 h.

[0015] In some embodiments, the BG-11 culture medium includes NaNO3, K2HPO4·3H2O, Na2CO3, citric acid, ferric ammonium citrate, EDTA-Na2, CaCl2·2H2O, MgSO4·7H2O, H3BO3, MnCl2·4H2O, ZnSO4·7H2O, Na2MoO4·2H2O, CuSO4·5H2O, and Co(NO3)2·6H2O. Preferably, the BG-11 culture medium is shown in Table 1.

[0016] In some embodiments, the arsenic concentration in the remediation water system is 10~100 μg / L, preferably 10 μg / L, 20 μg / L, 30 μg / L, 40 μg / L, 50 μg / L, 60 μg / L, 70 μg / L, 80 μg / L, 90 μg / L, or 100 μg / L.

[0017] In some embodiments, in S3, the basic repair cycle for continuous repair is 21 days.

[0018] In some embodiments, in S3, continuous repair culture is carried out at a temperature of 28~33 ℃, with a light exposure of ≥8 h per day, aeration 3 times a day for 1 h each time, and pH stable at 6.1~6.5 for 21 consecutive days. The modified Hogland nutrient solution is replaced every 7 days to maintain the nutritional stability of the system.

[0019] In some embodiments, the modified Hogland nutrient solution has a nitrogen-to-phosphorus molar ratio of 32:1, a nitrate-to-nitrogen ratio of 9:1, and a significant reduction in phosphorus sources. The amount of macroelements such as calcium, magnesium, and potassium is reduced by 55% to lower the total ionic strength, weaken the interference of high-salt ions on arsenic detection, and enhance pH buffering capacity to adapt to the characteristics of natural freshwater environments.

[0020] In some embodiments, in S3, common Chlorella solution is replenished every 3 months, and senescent Vallisneria plants are harvested and new plants are added every 6 months. Common Chlorella colonizes the surface of Vallisneria in the form of a dense biofilm, increasing the abundance of hydroxyl, amino, carboxyl, and polysaccharide CO2 polar functional groups on the surface of Vallisneria, providing binding sites for arsenic.

[0021] The mechanism by which the common Chlorella-Vallisneria symbiotic system enhances arsenic accumulation and stress resistance: 1. Increased interfacial sites and arsenic binding sites: Common Chlorella covers the surface of the rhizomes and leaves of Vallisneria natans with a dense biofilm and secretes a large number of extracellular polymers, which significantly increases the abundance of polar functional groups such as hydroxyl, amino, carboxyl, and polysaccharide CO on the surface of Vallisneria natans, providing a large number of adsorption and complexation sites for arsenate and greatly improving the arsenic capture and fixation capacity.

[0022] 2. Activation of rhizosphere arsenic forms, improving absorbability: Chlorella vulgaris regulates rhizosphere pH and releases dissolved organic matter through metabolism, converting poorly absorbed fixed arsenic into readily absorbable arsenic by Vallisneria natans, reducing arsenic blockage in the rhizosphere, enhancing arsenic bioavailability, and promoting rapid absorption by Vallisneria natans.

[0023] 3. Physiological stress protection and improved repair stability: Common Chlorella significantly alleviates the stress damage of arsenic to Vallisneria natans: delays chlorophyll degradation and increases SPAD value (relative chlorophyll value); reduces MDA (malondialdehyde) content and alleviates membrane lipid peroxidation; maintains SOD (superoxide dismutase) activity and enhances antioxidant capacity; promotes plant height and biomass growth, enabling Vallisneria natans to grow stably and accumulate continuously in high arsenic environments.

[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention uses *Chlorella vulgaris* as the functional algae species to construct a stable symbiotic system with *Vallisneria natans*. *Chlorella vulgaris* colonizes the surface of *Vallisneria natans* via a dense biofilm, enhancing the accumulation and stress resistance of *Vallisneria natans* for arsenic through interfacial functional group amplification, rhizosphere arsenic speciation activation, photosynthetic protection, and antioxidant regulation. Under 100 μg / L arsenic stress, the arsenic accumulation stability of *Vallisneria natans* is increased by 32.30% compared to *Vallisneria natans* alone, with a maximum increase of 14.29% in leaf SPAD value and a decrease of 17.60% in MDA content, significantly improving remediation efficiency and stress resistance. This invention solves the problems of low remediation efficiency of *Vallisneria natans* alone, susceptibility to damage under high arsenic stress, and insufficient arsenic accumulation capacity. It is suitable for efficient ecological remediation of arsenic-polluted water bodies such as mining areas, rivers, and lakes, and has advantages such as high efficiency, strong stress resistance, ecological safety, and simple operation and maintenance. Specifically: 1. Significantly improved remediation efficiency: After common Chlorella and Vallisneria natans coexisted, under 100 μg / L arsenic stress for 21 days, the overall arsenic content of Vallisneria natans increased by 32.30% compared with the control group without algae, significantly promoting the translocation of arsenic to Vallisneria natans and effectively solving the technical problem of low enrichment efficiency of aquatic plants in water bodies with high concentrations of arsenic pollution.

[0025] 2. Enhanced plant stress resistance: Common Chlorella can significantly alleviate the growth inhibition of Vallisneria natans by arsenic, increase plant height and biomass; increase the SPAD value of Vallisneria natans leaves by up to 14.29%, protecting the photosynthetic system; reduce MDA content by 17.60%, maintain high SOD activity, reduce oxidative damage, ensure normal growth and metabolism of Vallisneria natans in high arsenic environment, and enhance the stress resistance of Vallisneria natans.

[0026] 3. Significantly increased binding sites: Common Chlorella colonizes the rhizomes and leaves of Vallisneria natans in the form of dense biofilms, significantly increasing the abundance of polar functional groups such as hydroxyl, amino, carboxyl, and polysaccharide CO on the surface of Vallisneria natans, providing a large number of binding sites for arsenate, and enhancing the adsorption and fixation of arsenic at the micro-interface.

[0027] 4. Ecological safety and no secondary pollution: It adopts a pure biological symbiotic system, which does not require the addition of chemical agents, does not damage the original aquatic ecological structure, and can also improve the dissolved oxygen level of the water, thus having the added value of water purification and ecological improvement.

[0028] 5. Wide range of applications: The algae species are readily available and the system is easy to construct. It is suitable for water bodies polluted with arsenic concentrations of 10~100μg / L and can be applied to various remediation scenarios such as mine tailwater, smelting wastewater, polluted rivers and lakes. 6. Simple operation and maintenance, low cost: No complicated equipment is required. The repair effect is maintained stably by relying on the algae-grass symbiosis system. The operation and maintenance cost is low, it is easy to engineer, and it is suitable for large-scale application.

[0029] Terminology Explanation Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0030] It should be further appreciated that certain features of the invention, for clarity, have been described in multiple independent embodiments, but may also be provided in combination in a single embodiment. Conversely, various features of the invention, for brevity, have been described in a single embodiment, but may also be provided individually or in any suitable sub-combination.

[0031] Unless otherwise stated, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. All patents and publications related to this invention are incorporated herein by reference in their entirety.

[0032] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] In the following content, all figures disclosed herein, whether or not they use words such as "approximately" or "about," are approximate values. The value of each figure may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a figure with a value of N is disclosed, any figure with a value of N±1%, N±2%, N±3%, N±5%, N±7%, N±8%, N±10%, N±15%, or N±20% will be explicitly disclosed, where "±" indicates addition or subtraction. Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the symbiotic system in Example 1.

[0035] Figure 2 This is a SEM image of Chlorella vulgaris attached to the surface of the rhizome of Vallisneria natans.

[0036] Figure 3 This is a graph showing the long-term changes in arsenic concentration in water bodies for different treatment groups. Figure 3 (a): Arsenic concentration 10 μg / L; Figure 3 (b): Arsenic concentration 50 μg / L; Figure 3 (c): Arsenic concentration 100 μg / L. Different letters in the figure indicate significant differences at the 0.05 level.

[0037] Figure 4 The infrared spectra of rhizomes of *Vallisneria natans* cultured for 14 days under 100 μg / L arsenic stress are shown. The blue curve represents *Vallisneria natans* cultured alone, and the red curve represents *Vallisneria natans* co-cultured with *Chlorella vulgaris*.

[0038] Figure 5 Infrared spectra of leaves of *Vallisneria natans* cultured for 14 days under 100 μg / L arsenic stress. The blue curve represents the *Vallisneria natans* cultured alone, and the red curve represents the *Vallisneria natans* co-cultured with *Chlorella vulgaris*. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0040] All reagents used in this invention can be purchased commercially or prepared by the methods described in this invention.

[0041] In this invention, room temperature / normal temperature refers to 20~30℃, preferably 25~30℃.

[0042] Example 1: In-situ ecological restoration of water bodies with an initial arsenic concentration of 100 μg / L like Figure 1 As shown, 1. Pretreatment of Vallisneria natans: Select Vallisneria natans with a plant height of 30 cm and well-developed root system. After washing with deionized water, transfer them to a culture device containing 1 / 2 Hoagland nutrient solution and allow them to adapt to hydroponics for 15 days. Culture environment conditions: temperature 28~33℃, daily full-spectrum light duration ≥8 h, aeration 3 times a day for 1 h each time, and nutrient solution pH stable at 6.1~6.5. Culture for 15 days until the plants have stably sprouted and have uniform growth status, and then use them for cultivation.

[0043] 2. Common Chlorella ( Chlorella vulgaris Expansion culture: Using BG-11 medium (Table 1), the algae were expanded in an artificial climate incubator with a temperature of 23±0.5 ℃, a light intensity of 3960 lux, and a light-dark cycle of 12 h:12 h until the algal solution reached its OD value. 680 =1.00±0.05 logarithmic growth period, for future use.

[0044] Table 1. Formulation of BG-11 medium (1 L)

[0045] 3. System Construction: (1) Symbiotic system group: 5 cm glass beads were laid in a glass tank culture device (67 cm × 45 cm × 35.5 cm), 5 pretreated Vallisneria natans were planted, and modified Hogland nutrient solution was added (the nitrogen-phosphorus molar ratio was adjusted to 32:1, the nitrate-ammonium nitrogen ratio was set to 9:1 and the phosphorus source was significantly reduced, and the amount of macroelements such as calcium, magnesium and potassium was reduced by 55% to reduce the total ionic strength, weaken the interference of high salt ions on arsenic detection, and at the same time strengthen the pH buffering capacity to adapt to the characteristics of natural freshwater environment); 5% (v / v) of the total volume of the remediation water system was inoculated with common Chlorella in the logarithmic growth phase to construct a common Chlorella-Vallisneria natans symbiotic system, and the arsenic concentration in the remediation water system was 100 μg / L.

[0046] (2) Single Vallisneria group: without inoculation with Chlorella vulgaris. The rest are the same as (1).

[0047] (3) Algae-free control group: No common Chlorella was inoculated, and no Vallisneria natans was planted. The rest was the same as (1).

[0048] (4) Single Chlorella group: only Chlorella vulgaris was inoculated in the water. The rest is the same as (1).

[0049] (5) Common green algae-Vallisneria group: Common green algae were inoculated instead of common Chlorella in the water. The rest is the same as (1).

[0050] 4. Synergistic repair culture: Temperature 28~33 ℃, light ≥8 h per day, aeration 3 times a day for 1 h each time, pH stable at 6.1~6.5, culture continuously for 21 days, change the modified Hogland nutrient solution every 7 days to maintain the nutritional stability of the symbiotic system.

[0051] 5. Effect verification and repair completion: After the repair is completed, the soaked plants are harvested and the relevant effects are verified.

[0052] like Figure 2 As shown, *Chlorella vulgaris* in the symbiotic system can colonize and form a dense biofilm on the rhizomes and leaves of *Vallisneria natans*. The SPAD value of *Vallisneria natans* leaves increased by up to 14.29%, MDA content decreased by 17.60%, and SOD activity increased by 11.97%.

[0053] like Figure 3 As shown in (c), after 21 days of cultivation, the residual arsenic concentration in the water of the symbiotic system group was 32.37% lower than that of the single *Vallisneria natans* group; the overall arsenic content of *Vallisneria natans* in the symbiotic system group was 32.30% higher than that of the single *Vallisneria natans* group, and the arsenic content in the rhizomes of *Vallisneria natans* in the symbiotic system group was stable, indicating stable arsenic accumulation; the single *Vallisneria natans* group relied solely on the plant's own absorption and fixation of arsenic, resulting in low overall remediation efficiency and significant oxidative physiological damage to the plant under high arsenic stress. After 21 days of cultivation, the residual arsenic concentration in the water of the symbiotic system group was 28.65% lower than that of the single *Chlorella vulgaris* group; the overall arsenic content of *Vallisneria natans* in the symbiotic system group was 24.88% higher than that of the single *Chlorella vulgaris* group. Common green algae-Vallisneria group: The common green algae-Vallisneria system cannot form a dense biofilm like that of common Chlorella on the surface of Vallisneria, and the stability of arsenic enrichment is improved by less than 10%, with no obvious synergistic effect.

[0054] like Figure 4 and Figure 5 The images shown are Fourier transform infrared spectra of leaves and rhizomes of *Vallisneria natans* in a single plant and in a *Vallisneria natans*-*Chlorella vulgaris* symbiotic system, respectively. Compared to the single *Vallisneria natans* group, the leaves and rhizomes of *Vallisneria natans* in the symbiotic system show higher wavelengths at 3420 cm⁻¹. - ¹Near hydroxyl / amino characteristic peaks, 1640 cm⁻¹ - ¹Near the characteristic peak of amide C=O, 1000–1350 cm⁻¹ - ¹The absorption intensity of the CO characteristic peak of polysaccharides in the interval was significantly enhanced, indicating that after colonization by Chlorella vulgaris, a large number of active functional groups of hydroxyl, amino and polysaccharide active groups can be induced on the surface of the rhizomes and leaves of Vallisneria natans. The abundant active functional groups can provide more complexation and adsorption sites for arsenic ions, revealing the intrinsic mechanism of synergistic enrichment and fixation of arsenic in the algae-grass symbiotic system at the micro-interface level.

[0055] Example 2: In-situ ecological restoration of water bodies with an initial arsenic concentration of 50 μg / L 1. The pretreatment of Vallisneria natans is the same as in Example 1.

[0056] 2. The propagation of common Chlorella is the same as in Example 1.

[0057] 3. System construction: (1) Symbiotic system group, (2) Single Vallisneria group, (3) Algae-free control group, (4) Single Chlorella group are all the same as in Example 1, except that the arsenic concentration in the water is 50 μg / L.

[0058] 4. The culture conditions for repair are the same as in Example 1.

[0059] 5. Repair effect: such as Figure 3 As shown in (b), after 21 days of cultivation, the residual arsenic concentration in the water of the symbiotic system group was 28.12% lower than that of the single Vallisneria natans group; the residual arsenic concentration in the water of the symbiotic system group was 26.33% lower than that of the single Chlorella vulgaris group; the overall arsenic content of Vallisneria natans in the symbiotic system group was 28.25% higher than that of the control group without algae; the biomass of Vallisneria natans was significantly increased, with the highest increase in SPAD value of leaves by 14.06%, a decrease in MDA content by 15.85%, and an increase in SOD activity by 15.57%.

[0060] The results show that the present invention still possesses stable in-situ ecological restoration capabilities that are superior to existing technologies in water bodies contaminated with low to medium concentrations of arsenic.

[0061] Example 3: In-situ ecological restoration of water bodies with an initial arsenic concentration of 10 μg / L 1. The pretreatment of Vallisneria natans is the same as in Example 1.

[0062] 2. The propagation of common Chlorella is the same as in Example 1.

[0063] 3. System construction: (1) Symbiotic system group, (2) Single Vallisneria group, (3) Algae-free control group, and (4) Single Chlorella group are all the same as in Example 1, except that the arsenic concentration in the water is 10 μg / L.

[0064] 4. The culture conditions for repair are the same as in Example 1.

[0065] 5. Repair effect: such as Figure 3 As shown in (a), compared with the algae-free control group, the residual arsenic concentration in the water of the symbiotic system group was 51.56% lower than that of the single Vallisneria group within 6 months of cultivation; the overall arsenic content of Vallisneria in the symbiotic system group was 29.91% higher than that of the algae-free control group; the growth status of Vallisneria was significantly better than that of the single Vallisneria group, and there was no arsenic stress damage.

[0066] The results of six months of long-term operation have proven that this invention can achieve long-term in-situ ecological restoration of water bodies with low concentrations of arsenic, fully meeting the restoration needs of ecologically sensitive water bodies such as water sources.

[0067] The method of this invention has been described through preferred embodiments. Those skilled in the art will readily be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and context of this invention to implement and apply the technology of this invention. Those skilled in the art can refer to the content herein to appropriately improve process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of this invention.

Claims

1. A highly efficient method for remediating arsenic pollution, characterized in that, Constructing a common Chlorella-Vallisneria symbiotic system for in-situ water remediation includes: S1: Select *Vallisneria natans* plants with a height of 25-35cm, acclimate them to hydroponics in Hogrange nutrient solution for 15 days, and then transplant them into the remediation water system. The hydroponic acclimatization temperature is 28-33℃, the pH is stable at 6.1-6.5, the daily full-spectrum light duration is ≥8 hours, and regular aeration is performed daily. Plant *Vallisneria natans* at a density of 30-60 plants per cubic meter of remediation water system. After planting, add modified Hogrange nutrient solution for cultivation. S2: Inoculate the expanded Chlorella vulgaris into the remediation water system at a rate of 2-8% (v / v) of the total volume of the remediation water system to construct a Chlorella vulgaris-Vallisneria natans symbiotic system. Chlorella vulgaris colonizes the surface of Vallisneria natans with a dense biofilm. S3: Continuous repair, supplemented with common Chlorella and harvested senescent plants to complete the repair. The basic repair cycle for continuous repair is 21 days. Continuous repair culture: temperature 28~33 ℃, light ≥8 h per day, aeration 3 times a day for 1 h each time, pH stable at 6.1~6.5, continuous culture for 21 days, change the modified Hogland nutrient solution every 7 days to maintain the nutritional stability of the system.

2. The repair method according to claim 1, characterized in that, The common Chlorella was propagated using BG-11 medium and cultured to the logarithmic growth phase under conditions of 23±0.5 ℃, light intensity of 3960 lux, and light-dark cycle of 12 h:12 h.

3. The repair method according to claim 2, characterized in that, The BG-11 medium contains NaNO3, K2HPO4·3H2O, Na2CO3, citric acid, ferric ammonium citrate, EDTA-Na2, CaCl2·2H2O, MgSO4·7H2O, H3BO3, MnCl2·4H2O, ZnSO4·7H2O, Na2MoO4·2H2O, CuSO4·5H2O, and Co(NO3)2·6H2O.

4. The repair method according to claim 1, characterized in that, The arsenic concentration in the remediation water system is 10~100 μg / L.

5. The repair method according to claim 1, characterized in that, In S3, ordinary Chlorella solution is added every 3 months, and old Vallisneria plants are harvested and new plants are added every 6 months.

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