Ecological restoration method for restoring eutrophic water body by using microorganisms to enhance plants

Abstract

The invention provides an ecological restoration method for restoring a eutrophic water body by using microorganisms to reinforce plants, which comprises the following steps: screening bacillus, pseudomonas and rhodococcus strains from the eutrophic water body and bottom mud to prepare a composite microbial inoculant to synergistically degrade pollutants, so that the contents of total nitrogen and total phosphorus in the water body can be effectively reduced, and the water body quality is improved. The eutrophication problem is fundamentally solved. Acorus calamus, reeds and canna indica are selected and planted in a polyethylene floating bed according to the proportion of 1: 1: 1, and plants and microorganisms promote each other to improve the remediation effect. Defining culture conditions of each strain, and ensuring the quality of the inoculant; planting parameters are stipulated, and an ecological system is scientifically constructed. The water quality is monitored every week, the microbial agent feeding amount is adjusted according to the result, plants and floating objects are cleaned, and efficient operation of the system is ensured through dynamic management. According to the method, natural metabolism is utilized, secondary pollution is avoided, ecological balance recovery of the water body is promoted, environmental protection is achieved, the problem of eutrophication of the water body is effectively solved, and the remediation effect on the eutrophicated water body is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of water body ecological restoration, and more specifically, to an ecological restoration method for remediating eutrophic water bodies by strengthening plants with microorganisms. Background Art

[0002] With the rapid development of social economy and the continuous growth of population, a large amount of domestic sewage, industrial wastewater and agricultural non-point source pollution containing nutrients such as nitrogen and phosphorus are discharged into water bodies, resulting in increasingly serious water body eutrophication problems. Water body eutrophication can cause a large number of plankton such as algae to multiply, causing phenomena such as water blooms and red tides, reducing the transparency of water bodies, decreasing the dissolved oxygen content in water, and then affecting the survival and reproduction of aquatic organisms, destroying the water body ecological balance, and at the same time bringing a huge threat to drinking water safety and the sustainable utilization of water resources.

[0003] At present, the restoration methods for eutrophic water bodies mainly include physical methods, chemical methods and biological methods.

[0004] However, these existing technologies each have certain deficiencies:

[0005] Common physical restoration methods include water diversion and dilution, sediment dredging, artificial aeration, etc. Water diversion and dilution only temporarily reduce the concentration of pollutants in the water body, without fundamentally removing pollutants, and it requires a large amount of water resources and high costs; the sediment dredging project is huge and costly, and may cause secondary damage to the water body ecological environment during the dredging process; although artificial aeration can increase the dissolved oxygen content in the water body, its effect on removing nutrients such as nitrogen and phosphorus is limited and it cannot effectively solve the root cause of water body eutrophication.

[0006] The chemical method mainly removes pollutants in the water body by adding chemical agents such as flocculants and phosphorus removers to the water body. Although this method can quickly reduce the concentration of pollutants in the water body in the short term, the use of chemical agents may cause secondary pollution and have a negative impact on the water body ecological system. At the same time, the long-term use of chemical agents may also lead to changes in the microbial community structure in the water body, reducing the self-purification ability of the water body and being unfavorable to the long-term stability of the water body ecological environment.

[0007] Traditional bioremediation methods mainly use single microorganisms or plants to treat eutrophic water bodies. The metabolic capacity of single microorganisms is limited, and the range of pollutants they can degrade is narrow, making it difficult to comprehensively and effectively remove various pollutants in water bodies. Moreover, the adaptability and purification ability of single plants also have certain limitations and cannot maintain good growth and purification effects under different environmental conditions. In addition, traditional biological methods often lack scientific monitoring and management in practical applications and are difficult to adjust the remediation strategy in a timely manner according to the actual situation of the water body, resulting in unstable remediation effects and difficult to achieve the ideal remediation goal. Therefore, we propose an ecological remediation method for remediating eutrophic water bodies by microbial enhanced phytoremediation. Summary of the Invention

[0008] The object of the present invention is to address the problems raised in the existing background technology. To achieve the above object of the invention, the present invention provides the following technical solutions: An ecological remediation method for remediating eutrophic water bodies by microbial enhanced phytoremediation, comprising the following steps: Step 1, screening and culturing of microbial strains: Samples are collected from eutrophic water bodies and their bottom muds, and strains of Bacillus, Pseudomonas, and Rhodococcus with high nitrogen and phosphorus removal capabilities are screened out; each of the screened strains is inoculated into the corresponding liquid medium for culture, and after the culture is completed, the concentration of the bacterial solution is adjusted to 1×10 8 CFU / mL;

[0009] Step 2, preparation of microbial composite bacterium agents: The cultured bacterial solutions of Bacillus, Pseudomonas, and Rhodococcus are mixed in a volume ratio of 1:1:1 to prepare microbial composite bacterium agents;

[0010] Step 3, selection and pretreatment of aquatic plants: Acorus calamus, Phragmites australis, and Canna indica are selected as aquatic plants, and healthy seedlings of the same size are selected, washed clean with water, soaked in a 0.1% potassium permanganate solution for disinfection for 10 - 15 min, and then washed clean with water for standby;

[0011] Step 4, construction of an ecological remediation system: A planting floating bed made of polyethylene material is set in the eutrophic water body, and the spacing between the planting holes of the floating bed is 20 - 30 cm; the pretreated Acorus calamus, Phragmites australis, and Canna indica seedlings are planted on the floating bed in a ratio of 1:1:1, and one seedling is planted in each planting hole; around the floating bed after planting the aquatic plants, the microbial composite bacterium agent is evenly put in, and the dosage is 10 L / mu;

[0012] Step 5, Monitoring and management of the repair process: Regularly monitor water quality indicators such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen in the water body, with a monitoring cycle of once a week; According to the monitoring results, timely adjust the dosage of the microbial complex bacteria agent and the growth status of aquatic plants. If the nitrogen and phosphorus content in the water body is still relatively high, reapply the microbial complex bacteria agent every 15 - 20 days, with a dosage of 5 L / mu, and at the same time, promptly remove dead aquatic plants and floating objects.

[0013] As a preferred technical solution of the present invention, the culture conditions of the Bacillus strain are 30 °C, 180 r / min for 24 h.

[0014] As a preferred technical solution of the present invention, the culture conditions of the Pseudomonas strain are 28 °C, 160 r / min for 36 h.

[0015] As a preferred technical solution of the present invention, the culture conditions of the Rhodococcus strain are 25 °C, 150 r / min for 48 h.

[0016] As a preferred technical solution of the present invention, the planting floating bed is made of polyethylene material and has good buoyancy and stability.

[0017] As a preferred technical solution of the present invention, the temperature for rinsing with clean water in the pretreatment of aquatic plants is 23 ° - 26 °, and the number of rinsing times is 2 - 4 times.

[0018] As a preferred technical solution of the present invention, the planting ratio of the aquatic plants Acorus calamus, Phragmites australis, and Canna indica is 1:1:1.

[0019] As a preferred technical solution of the present invention, the dosage of the microbial complex bacteria agent is 10 L / mu, and the subsequent supplementary dosage is 5 L / mu.

[0020] As a preferred technical solution of the present invention, the monitoring cycle of the water quality indicators of the water body is once a week.

[0021] As a preferred technical solution of the present invention, if the nitrogen and phosphorus content in the water body is still relatively high, reapply the microbial complex bacteria agent every 15 - 20 days.

[0022] Compared with the prior art, the beneficial effects of the present invention:

[0023] The present invention screens strains of the genus Bacillus, the genus Pseudomonas, and the genus Rhodococcus with high nitrogen and phosphorus removal capabilities from eutrophic water bodies and their bottom muds. These specific strains have strong decomposition and conversion capabilities for nitrogen and phosphorus pollutants in eutrophic water bodies, can effectively reduce the content of total nitrogen and total phosphorus in the water body, and fundamentally solve the eutrophication problem.

[0024] The present invention mixes the bacterial solutions of the genus Bacillus, Pseudomonas, and Rhodococcus in a volume ratio of 1:1:1 to prepare a microbial composite bacterium agent. Strains of different genera can play a synergistic role during the metabolic process, expanding the range and efficiency of pollutant degradation, having a better treatment effect than a single strain, and being able to purify water bodies more comprehensively.

[0025] The present invention selects Acorus calamus, Phragmites australis, and Canna indica as aquatic plants to be used in combination with the microbial composite bacterium agent. Aquatic plants can absorb nutrients such as nitrogen and phosphorus in the water body through their roots, and at the same time provide a place for microorganisms to attach and survive; microorganisms can decompose organic pollutants that are difficult for plants to directly utilize and convert them into nutrients that plants can absorb. The two promote each other, significantly improving the repair effect on eutrophic water bodies.

[0026] The present invention specifies the respective culture conditions of the strains of the genus Bacillus, Pseudomonas, and Rhodococcus. For example, the Bacillus strains are cultured at 30°C and 180 r / min for 24 h, the Pseudomonas strains are cultured at 28°C and 160 r / min for 36 h, and the Rhodococcus strains are cultured at 25°C and 150 r / min for 48 h. The standardized culture conditions facilitate actual operation and control, ensure the stable quality of the cultured strains, and provide a reliable guarantee for the subsequent preparation of the composite bacterium agent.

[0027] The floating bed for planting in the present invention is made of polyethylene material and has good buoyancy and stability. This floating bed can provide a stable growth support for aquatic plants, ensure the normal growth of plants in the water body, and is not easily affected by external factors such as water flow and wind and waves, ensuring the stability of the ecological restoration system.

[0028] The present invention stipulates the planting ratio of aquatic plants (Acorus calamus, Phragmites australis, and Canna indica are 1:1:1), the spacing between planting holes (20 - 30 cm), and the dosage of the microbial composite bacterium agent (the initial dosage is 10 L / mu, and the subsequent supplementary dosage is 5 L / mu). These reasonable parameter settings make the construction of the ecological restoration system more scientific and standardized, and are conducive to plants and microorganisms to play the best repair effect.

[0029] The present invention regularly (once a week) monitors water quality indicators such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen in the water body, and can timely grasp the progress of water body restoration and water quality changes. Through the monitoring data, the repair effect can be accurately judged, providing a scientific basis for subsequent adjustment and management.

[0030] According to the water quality monitoring results, the present invention timely adjusts the dosage of the microbial complex bactericide and the growth status of aquatic plants. When the nitrogen and phosphorus contents in the water body are still relatively high, the microbial complex bactericide is put in again every 15 - 20 days, and at the same time, the dead aquatic plants and floating objects are removed in time. This dynamic management method can flexibly adjust the restoration strategy according to the actual situation, ensure that the ecological restoration system is always in the best operating state, and improve the restoration efficiency and effect.

[0031] The present invention mainly utilizes the natural metabolic functions of microorganisms and aquatic plants to repair eutrophic water bodies, avoiding the problem of secondary pollution that may be brought about by the use of chemical agents, and conforming to the concept of ecological environmental protection. While repairing the water body, the growth and reproduction of aquatic plants and microorganisms can provide food and habitats for other organisms in the water body, promote the restoration and balance of the water body ecosystem, and improve the ecological environmental quality of the water body. Brief Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the experimental data provided by the present invention;

[0033] Figure 2 It is a schematic diagram of the experimental data provided by the present invention;

[0034] Figure 3 It is a schematic diagram of the experimental data provided by the present invention;

[0035] Figure 4 It is a schematic diagram of the method flow provided by the present invention. Detailed Description of the Invention

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0037] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed present invention, but merely represents some embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention. It should be noted that, without conflict, the embodiments and the features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0038] Example 1: An ecological restoration method for remediating eutrophic water bodies by microbial enhanced phytoremediation, comprising the following steps: Step 1, screening and culturing of microbial strains: Samples are collected from eutrophic water bodies and their sediments, and strains of the genera Bacillus, Pseudomonas, and Rhodococcus with high nitrogen and phosphorus removal capabilities are screened out; the screened strains are respectively inoculated into corresponding liquid media for culturing, and after the culturing is completed, the concentration of the bacterial solution is adjusted to 1×10 8 CFU / mL;

[0039] Step 2, preparation of microbial composite bacterium agent: The cultured bacterial solutions of the genera Bacillus, Pseudomonas, and Rhodococcus are mixed in a volume ratio of 1:1:1 to prepare a microbial composite bacterium agent;

[0040] Step 3, selection and pretreatment of aquatic plants: Acorus calamus, Phragmites australis, and Canna indica are selected as aquatic plants, and robust and uniformly sized seedlings are selected, washed clean with clean water, soaked in a 0.1% potassium permanganate solution for disinfection for 10 - 15 min, and then washed clean with clean water for standby;

[0041] Step 4, construction of the ecological restoration system: Polyethylene planting floating beds are set in the eutrophic water body, and the spacing between the planting holes of the floating beds is 20 - 30 cm; the pretreated seedlings of Acorus calamus, Phragmites australis, and Canna indica are planted on the floating beds in a ratio of 1:1:1, and one seedling is planted in each planting hole; around the floating beds after planting the aquatic plants, the microbial composite bacterium agent is evenly put in, and the dosage is 10 L / mu;

[0042] Step 5, monitoring and management during the restoration process: Regularly monitor water quality indicators such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen in the water body, and the monitoring period is once a week; according to the monitoring results, timely adjust the dosage of the microbial composite bacterium agent and the growth status of the aquatic plants. If the nitrogen and phosphorus contents in the water body are still relatively high, the microbial composite bacterium agent is put in again every 15 - 20 days, and the dosage is 5 L / mu. At the same time, dead aquatic plants and floating objects are promptly removed.

[0043] The culture conditions for Bacillus strains are culturing at 30°C and 180 r / min for 24 h.

[0044] The culture conditions for Pseudomonas strains are culturing at 28°C and 160 r / min for 36 h.

[0045] The culture conditions for Rhodococcus strains are culturing at 25°C and 150 r / min for 48 h.

[0046] The planting floating beds are made of polyethylene material and have good buoyancy and stability.

[0047] The temperature for washing with clean water during the pretreatment of aquatic plants is 23° - 26°, and the number of washing times is 2 - 4 times.

[0048] The planting ratio of aquatic plants Acorus calamus, Phragmites australis and Canna indica is 1:1:1.

[0049] The dosage of the microbial complex bacterium agent is 10 L / mu, and the subsequent supplementary dosage is 5 L / mu.

[0050] The monitoring period for water quality indicators of the water body is once a week.

[0051] The nitrogen and phosphorus contents in the water body are still relatively high, and the microbial complex bacterium agent is put in again every 15 - 20 days.

[0052] Example 2: An ecological restoration method for remediating eutrophic water bodies by microbial - enhanced phytoremediation. A small artificial eutrophic pond with an area of about 10 mu is selected as the remediation object. Due to the fertilizer runoff from surrounding farmland and the discharge of a small amount of domestic sewage, the water body of this pond is eutrophic and the water quality is poor. Before remediation, the total nitrogen content of the water body is 4.5 mg / L, the total phosphorus content is 0.4 mg / L, the chemical oxygen demand (COD) is 28 mg / L, and the dissolved oxygen (DO) is 2.5 mg / L.

[0053] Screening and culturing of microbial strains

[0054] Samples are collected from the bottom mud and water body of the pond, and the samples are inoculated into a selective medium containing specific nitrogen sources (nitrate nitrogen, ammonium nitrogen) and phosphorus sources (phosphate) for enrichment culture. After multiple separation and purification, strains of Bacillus, Pseudomonas and Rhodococcus with high - efficiency nitrogen and phosphorus removal ability are screened out.

[0055] The strains of Bacillus are inoculated into a nutrient broth medium and cultured in a shaker at 30 °C and 180 r / min for 24 h. The strains of Pseudomonas are inoculated into a peptone beef extract medium and cultured at 28 °C and 160 r / min for 36 h. The strains of Rhodococcus are inoculated into a malt extract medium and cultured at 25 °C and 150 r / min for 48 h. After the culture is completed, the concentration of the bacterial solution is measured using a hemocytometer or a spectrophotometer, and the concentration of each bacterial solution is adjusted to 1×10 8 CFU / mL.

[0056] Preparation of microbial complex bacterium agent

[0057] According to the volume ratio of 1:1:1, the cultured bacterial solutions of Bacillus, Pseudomonas and Rhodococcus are fully mixed to prepare a microbial complex bacterium agent. The mixing process is carried out under aseptic conditions to ensure the quality of the complex bacterium agent.

[0058] Selection and pretreatment of aquatic plants

[0059] Select calamus, reed and canna as aquatic plants. Purchase healthy seedlings of the same size from local nurseries.

[0060] Rinse the seedlings with clean water to remove the soil and impurities on the surface. Then soak the seedlings in a 0.1% potassium permanganate solution for 12 minutes for disinfection, and then rinse them thoroughly with clean water to remove the residual disinfectant.

[0061] Construction of the ecological restoration system

[0062] Set up polyethylene planting floating beds in the pond. The floating beds are designed as rectangles, and their sizes are adjusted according to the shape and size of the pond. The spacing between planting holes is 20 cm.

[0063] Plant the pre-treated calamus, reed and canna seedlings in the planting holes of the floating bed at a ratio of 1:1:1, with one seedling planted in each planting hole. Ensure that the roots of the seedlings are stretched out and firmly fixed to the floating bed.

[0064] Around the floating bed with the aquatic plants planted, use a sprayer or watering can to evenly apply the microbial complex bactericide, with a dosage of 10 L / mu. Try to make the complex bactericide evenly dispersed in the water body during application.

[0065] Monitoring and management during the restoration process

[0066] Use professional water quality detection instruments to monitor water quality indicators such as total nitrogen, total phosphorus, chemical oxygen demand and dissolved oxygen in the water body every week. Record the data of each monitoring and draw a water quality change curve.

[0067] During the restoration process, it was observed that the nitrogen and phosphorus contents in the water body were still relatively high on the 20th day. So, the microbial complex bactericide was applied again on the 20th day and the 35th day respectively, with a dosage of 5 L / mu.

[0068] Regularly inspect the pond, and promptly remove the dead aquatic plants and floating objects on the water surface to prevent secondary pollution of the water quality caused by their decomposition. At the same time, check the stability of the floating bed, and repair or replace it in time if it is damaged.

[0069] Restoration effect

[0070] After 80 days of restoration, the total nitrogen content in the pond water body dropped to 0.8 mg / L, the total phosphorus content dropped to 0.08 mg / L, the chemical oxygen demand dropped to 8 mg / L, and the dissolved oxygen increased to 6 mg / L. The water quality was significantly improved, the water transparency increased, the water color changed from the original turbid green to clear light blue, the algae on the water surface decreased significantly, the aquatic plants grew vigorously, and the pond ecosystem gradually restored balance.

[0071] Example 3: Partial restoration of an urban landscape river

[0072] Overview of the Landscape River

[0073] A section of the urban landscape river with a length of about 200 meters and a width of about 15 meters was selected for restoration. Due to the discharge of surrounding commercial activities and domestic sewage, the water body in this area has become eutrophic and the water quality has deteriorated. Before restoration, the total nitrogen content in the water body was 6 mg / L, the total phosphorus content was 0.6 mg / L, the chemical oxygen demand was 35 mg / L, and the dissolved oxygen was 2 mg / L.

[0074] Screening and Cultivation of Microbial Strains

[0075] Samples were collected from the sediment and water body of the landscape river, and highly efficient nitrogen and phosphorus removal strains of Bacillus, Pseudomonas, and Rhodococcus were screened using the same screening method as in Example 1.

[0076] Each strain was cultured according to the corresponding culture conditions. The Bacillus strain was cultured at 30 °C and 180 r / min for 24 h, the Pseudomonas strain was cultured at 28 °C and 160 r / min for 36 h, and the Rhodococcus strain was cultured at 25 °C and 150 r / min for 48 h. After the culture was completed, the concentration of the bacterial solution was adjusted to 1×10 8 CFU / mL.

[0077] Preparation of Microbial Composite Bactericide

[0078] The three cultured bacterial solutions were mixed in a volume ratio of 1:1:1 to prepare a microbial composite bactericide.

[0079] Selection and Pretreatment of Aquatic Plants

[0080] Acorus calamus, Phragmites australis, and Canna indica were selected as restoration plants, and seedlings with good growth and no diseases and pests were selected.

[0081] After rinsing the seedlings with clean water, they were soaked in a 0.1% potassium permanganate solution for 15 min for disinfection, and then washed with clean water.

[0082] Construction of the Ecological Restoration System

[0083] A planting floating bed made of polyethylene was fabricated. The floating bed was in a long strip shape to adapt to the shape of the landscape river. The spacing between the planting holes on the floating bed was set at 30 cm.

[0084] The pretreated seedlings of Acorus calamus, Phragmites australis, and Canna indica were planted on the floating bed in a ratio of 1:1:1, with one seedling planted in each planting hole.

[0085] The microbial composite bactericide was evenly put around the floating bed where the aquatic plants were planted. The application rate was calculated according to the area of this region as 10 L / mu.

[0086] Monitoring and Management during the Restoration Process

[0087] The water body in the repaired area is sampled weekly, and indicators such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen are analyzed using laboratory testing equipment.

[0088] On the 18th and 32nd days of the repair, according to the water quality monitoring results, it was found that the nitrogen and phosphorus contents were still higher than expected, and 5 L / mu of the microbial complex agent was added again respectively.

[0089] Special personnel are arranged to regularly clean up the garbage and dead aquatic plants in the repaired area to keep the water body clean. At the same time, observe the growth of aquatic plants and replace the poorly growing plants in a timely manner.

[0090] Repair effect

[0091] After 90 days of repair, the total nitrogen content of the water body in this area of the landscape river decreased to 1.2 mg / L, the total phosphorus content decreased to 0.1 mg / L, the chemical oxygen demand decreased to 12 mg / L, and the dissolved oxygen increased to 5 mg / L. The water quality was significantly improved, the peculiar smell of the water body was eliminated, the types and quantities of plankton in the water increased, and the ecological landscape of the landscape river was significantly improved.

[0092] Control Example 1: Single-plant repair

[0093] Experimental setup

[0094] In a small artificial eutrophic pond identical to that in Example 1, an area of the same size was set up for a single-plant repair experiment. The same Acorus calamus, Phragmites australis, and Canna indica seedlings as in Example 1 were planted on the floating beds at the same planting ratio and density, but no microbial complex agent was added.

[0095] Monitoring and management

[0096] The water quality indicators of the water body in this area are monitored weekly, and dead aquatic plants and floating objects are regularly cleaned up.

[0097] Repair effect

[0098] After 80 days of repair, the total nitrogen content of the water body decreased to 2.5 mg / L, the total phosphorus content decreased to 0.2 mg / L, the chemical oxygen demand decreased to 18 mg / L, and the dissolved oxygen increased to 4 mg / L. Compared with Example 1, the water quality improvement effect was significantly worse, indicating that the single-plant repair has limited ability to repair eutrophic water bodies.

[0099] Control Example 2: Single-microbial repair

[0100] Experimental setup

[0101] In the urban landscape river repair area identical to that in Example 2, a control area was set up for a single-microbial repair experiment. The microbial complex agent was prepared and added according to the method of Example 2, but no aquatic plants were planted.

[0102] Monitoring and Management

[0103] Monitor the water quality indicators of the water body in this area weekly and clean up the floating debris on the water surface in a timely manner.

[0104] Remediation Effect

[0105] After 90 days of remediation, the total nitrogen content of the water body decreased to 3.5 mg / L, the total phosphorus content decreased to 0.3 mg / L, the chemical oxygen demand decreased to 22 mg / L, and the dissolved oxygen increased to 3.5 mg / L. Compared with Example 2, the remediation effect is not as good as that of the combined remediation of microorganisms and plants, indicating that single microorganism remediation has limitations in improving the water ecological environment.

[0106] Experimental Example:

[0107] Experimental Purpose: To verify the influence of different combinations of microbial strains on the remediation effect of eutrophic water bodies Experimental Design

[0108] Group Setting: Set 4 experimental groups, namely Experimental Group A (single strain of Bacillus), Experimental Group B (single strain of Pseudomonas), Experimental Group C (single strain of Rhodococcus), and Experimental Group D (compound bactericide with Bacillus, Pseudomonas, and Rhodococcus mixed in a volume ratio of 1:1:1). Set 3 parallel samples in each experimental group.

[0109] Experimental Water Body: Select small experimental pools with similar eutrophication levels, and the volume of each pool is 5m 3 , the total nitrogen content of the water body is about 5 mg / L, the total phosphorus content is about 0.5 mg / L, the chemical oxygen demand is about 30 mg / L, and the dissolved oxygen is about 3 mg / L.

[0110] Experimental Process: Add the corresponding bacterial solution to the pools in each experimental group, and the dosage is 10 L / 5m 3 . At the same time, set planting floating beds with the same specifications in each pool, and plant Acorus calamus, Phragmites australis, and Canna indica seedlings, and the planting ratio is 1:1:1. The experimental period is 60 days, and the indicators such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen of the water body are monitored weekly.

[0111] Experimental Results

[0112] Total Nitrogen Removal Effect: At the end of the experiment, the total nitrogen content in Experimental Group D decreased to less than 1 mg / L, and the removal rate reached more than 80%; the total nitrogen content in Experimental Group A decreased to about 2.5 mg / L, and the removal rate was about 50%; the total nitrogen content in Experimental Group B decreased to about 2.8 mg / L, and the removal rate was about 44%; the total nitrogen content in Experimental Group C decreased to about 3 mg / L, and the removal rate was about 40%. It shows that the compound bactericide is significantly superior to the single strain in total nitrogen removal.

[0113] Total phosphorus removal effect: The total phosphorus content in experimental group D decreased to below 0.1 mg / L, and the removal rate reached over 80%; the total phosphorus content in experimental group A decreased to around 0.25 mg / L, and the removal rate was about 50%; the total phosphorus content in experimental group B decreased to around 0.28 mg / L, and the removal rate was about 44%; the total phosphorus content in experimental group C decreased to around 0.3 mg / L, and the removal rate was about 40%. It also shows that the composite bacterium agent has a better removal effect on total phosphorus.

[0114] Changes in chemical oxygen demand and dissolved oxygen: The chemical oxygen demand in experimental group D decreased to below 10 mg / L, and the dissolved oxygen increased to above 5 mg / L, with obvious water quality improvement; while the chemical oxygen demand in experimental groups A, B, and C decreased to around 15 mg / L, 16 mg / L, and 18 mg / L respectively, and the dissolved oxygen increased to around 4 mg / L, 3.8 mg / L, and 3.5 mg / L respectively. It shows that the composite bacterium agent can more effectively reduce the organic matter content in water bodies and improve the dissolved oxygen level.

[0115] Experimental example 2: Influence of different combinations of aquatic plants on the remediation effect of eutrophic water bodies

[0116] Experimental design

[0117] Group setting: Four experimental groups were set up, namely experimental group E (single plant of Acorus calamus), experimental group F (single plant of Phragmites australis), experimental group G (single plant of Canna indica), and experimental group H (a combination of Acorus calamus, Phragmites australis, and Canna indica in a ratio of 1:1:1). Three parallel samples were set up in each experimental group.

[0118] Experimental water body: Small experimental pools with the same eutrophication degree as in experimental example 1 were selected, and the volume of each pool was 5 m 3 。

[0119] Experimental process: Planting floating beds of the same specification were set up in each pool, and the corresponding aquatic plants were planted respectively. At the same time, a microbial composite bacterium agent (a mixture of Bacillus, Pseudomonas, and Rhodococcus in a volume ratio of 1:1:1) was put into each pool, and the dosage was 10 L / 5 m 3 。The experimental period was 60 days, and indicators such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen in the water body were monitored weekly.

[0120] Experimental results

[0121] Total nitrogen removal effect: At the end of the experiment, the total nitrogen content in experimental group H decreased to about 1.2 mg / L, and the removal rate was about 76%; the total nitrogen content in experimental group E decreased to about 2 mg / L, and the removal rate was about 60%; the total nitrogen content in experimental group F decreased to about 2.2 mg / L, and the removal rate was about 56%; the total nitrogen content in experimental group G decreased to about 2.3 mg / L, and the removal rate was about 54%. It shows that the combination of three aquatic plants is more effective in total nitrogen removal than single plants.

[0122] Total phosphorus removal effect: The total phosphorus content in experimental group H decreased to about 0.12 mg / L, and the removal rate was about 76%; the total phosphorus content in experimental group E decreased to about 0.2 mg / L, and the removal rate was about 60%; the total phosphorus content in experimental group F decreased to about 0.22 mg / L, and the removal rate was about 56%; the total phosphorus content in experimental group G decreased to about 0.23 mg / L, and the removal rate was about 54%. It shows that the plant combination has a better effect on total phosphorus removal.

[0123] Changes in chemical oxygen demand and dissolved oxygen: The chemical oxygen demand in experimental group H decreased to about 12 mg / L, and the dissolved oxygen increased to about 4.8 mg / L; while the chemical oxygen demands in experimental groups E, F, and G decreased to about 16 mg / L, 17 mg / L, and 18 mg / L respectively, and the dissolved oxygen increased to about 4.2 mg / L, 4 mg / L, and 3.8 mg / L respectively. It shows that the combination of three aquatic plants can more effectively improve the chemical oxygen demand and dissolved oxygen conditions of the water body.

[0124] Experimental Example 3: Influence of different dosages of microbial complex bactericide on the remediation effect of eutrophic water bodies

[0125] Experimental design

[0126] Group setting: Four experimental groups were set up, namely experimental group I (dosage of microbial complex bactericide is 5 L / mu), experimental group J (dosage of microbial complex bactericide is 10 L / mu), experimental group K (dosage of microbial complex bactericide is 15 L / mu), and experimental group L (dosage of microbial complex bactericide is 20 L / mu). Three parallel samples were set in each experimental group.

[0127] Experimental water body: Small experimental ponds with similar eutrophication levels were selected. Each pond has an area of 1 mu, the total nitrogen content of the water body is about 5 mg / L, the total phosphorus content is about 0.5 mg / L, the chemical oxygen demand is about 30 mg / L, and the dissolved oxygen is about 3 mg / L.

[0128] Experimental process: Plant floating beds with the same specifications were set in each pond, and calamus, reed, and canna seedlings were planted in a ratio of 1:1:1. The microbial complex bactericide was put into the ponds of each experimental group according to the corresponding dosages. The experimental period was 60 days, and the indexes such as total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen of the water body were monitored weekly.

[0129] Experimental Results

[0130] Total nitrogen removal effect: At the end of the experiment, the total nitrogen content in experimental group J decreased to less than 1 mg / L, and the removal rate reached over 80%; the total nitrogen content in experimental group I decreased to about 1.5 mg / L, and the removal rate was about 70%; the total nitrogen content in experimental group K decreased to about 0.9 mg / L, and the removal rate was about 82%; the total nitrogen content in experimental group L decreased to about 0.9 mg / L, and the removal rate was about 82%. When the dosage exceeded 10 L / mu, the improvement of the total nitrogen removal effect was not obvious.

[0131] Total phosphorus removal effect: The total phosphorus content in experimental group J decreased to less than 0.1 mg / L, and the removal rate reached over 80%; the total phosphorus content in experimental group I decreased to about 0.15 mg / L, and the removal rate was about 70%; the total phosphorus content in experimental group K decreased to about 0.09 mg / L, and the removal rate was about 82%; the total phosphorus content in experimental group L decreased to about 0.09 mg / L, and the removal rate was about 82%. It also indicated that when the dosage exceeded 10 L / mu, the improvement of the total phosphorus removal effect was limited.

[0132] Changes in chemical oxygen demand and dissolved oxygen: The chemical oxygen demand in experimental group J decreased to less than 10 mg / L, and the dissolved oxygen increased to over 5 mg / L; the chemical oxygen demand in experimental group I decreased to about 13 mg / L, and the dissolved oxygen increased to about 4.5 mg / L; the chemical oxygen demand in experimental groups K and L decreased to about 9 mg / L, and the dissolved oxygen increased to about 5.2 mg / L. Considering the cost and effect comprehensively, a dosage of 10 L / mu was more appropriate.

[0133] (Microbial enhanced phytoremediation) Water quality index change data

[0134]

[0135] Water quality index change data of comparative example 1 (single phytoremediation)

[0136]

[0137]

[0138] Water quality index change data of comparative example 2 (single microbial remediation)

[0139]

[0140] Data analysis

[0141] Analysis of total nitrogen removal effect

[0142] It can be seen from the experimental data that in Example 1 (microbial enhanced phytoremediation), the total nitrogen content decreased from 5 mg / L to 0.9 mg / L, and the removal rate reached $(5 - 0.9)÷5×100\% = 82\%$.

[0143] In Comparative Example 1 (single phytoremediation), the total nitrogen content decreased from 5 mg / L to 2 mg / L, and the removal rate was $(5 - 2)÷5×100\% = 60\%$.

[0144] In Comparative Example 2 (single microbial remediation), the total nitrogen content decreased from 5 mg / L to 2.8 mg / L, and the removal rate was $(5 - 2.8)÷5×100\% = 44\%$.

[0145] By comparison, it can be seen that microbial enhanced phytoremediation is significantly more effective than single phytoremediation and single microbial remediation in terms of total nitrogen removal. This is because there is a synergistic effect between microorganisms and plants. Microorganisms can convert organic nitrogen into inorganic nitrogen, which is convenient for plants to absorb. At the same time, plants provide a living environment and some nutrients for microorganisms, promoting the metabolic activities of microorganisms, thereby improving the total nitrogen removal efficiency.

[0146] Analysis of total phosphorus removal effect

[0147] In Example 1, the total phosphorus content decreased from 0.5 mg / L to 0.1 mg / L, and the removal rate was $(0.5 - 0.1)÷0.5×100\% = 80\%$.

[0148] In Comparative Example 1, the total phosphorus content decreased from 0.5 mg / L to 0.2 mg / L, and the removal rate was $(0.5 - 0.2)÷0.5×100\% = 60\%$.

[0149] In Comparative Example 2, the total phosphorus content decreased from 0.5 mg / L to 0.25 mg / L, and the removal rate was $(0.5 - 0.25)÷0.5×100\% = 50\%$.

[0150] It also shows that microbial enhanced phytoremediation has a better effect on total phosphorus removal. Microorganisms can fix phosphorus in their bodies through assimilation, while plants can directly absorb phosphates in the water body. The synergistic effect of the two enhances the total phosphorus removal ability.

[0151] Analysis of chemical oxygen demand (COD) removal effect

[0152] In Example 1, the chemical oxygen demand decreased from 30 mg / L to 10 mg / L, and the removal rate was $(30 - 10)÷30×100\%≈66.7\%$.

[0153] In Comparative Example 1, the chemical oxygen demand decreased from 30 mg / L to 15 mg / L, and the removal rate was $(30 - 15)÷30×100\% = 50\%$.

[0154] The chemical oxygen demand of Comparative Example 2 decreased from 30 mg / L to 17 mg / L, and the removal rate was $(30 - 17)÷30×100\%≈43.3\%$.

[0155] It can be seen that microbial enhanced phytoremediation can more effectively reduce the organic matter content in water bodies. This is because microorganisms have a strong ability to decompose organic matter, and the substances secreted by plant roots also contribute to the degradation of organic matter. The combined action of the two improves the COD removal rate.

[0156] Analysis of the improvement effect of dissolved oxygen (DO)

[0157] The dissolved oxygen in Example 1 increased from 3 mg / L to 5.5 mg / L, an increase of 2.5 mg / L.

[0158] The dissolved oxygen in Comparative Example 1 increased from 3 mg / L to 4.5 mg / L, an increase of 1.5 mg / L.

[0159] The dissolved oxygen in Comparative Example 2 increased from 3 mg / L to 3.9 mg / L, an increase of 0.9 mg / L.

[0160] It shows that microbial enhanced phytoremediation can better increase the dissolved oxygen content in water bodies. Plants release oxygen through photosynthesis, and the process of microorganisms decomposing organic matter also consumes a certain amount of dissolved oxygen. However, under the combined action of the two, the dissolved oxygen in the water body is significantly increased as a whole.

[0161] 1. Remarkable remediation effect: The ecological remediation method of using microbial enhanced phytoremediation to treat eutrophic water bodies proposed by the present invention shows remarkable effects in the removal of total nitrogen, total phosphorus, reduction of chemical oxygen demand, and increase of dissolved oxygen. Compared with single phytoremediation and single microbial remediation, it has higher remediation efficiency and better water quality improvement ability.

[0162] 2. Advantage of synergistic effect: There is an obvious synergistic effect between microorganisms and plants. Microorganisms provide available nutrients for plants and improve the water body microenvironment. Plants provide habitats and oxygen for microorganisms. The two promote each other and jointly complete the remediation of eutrophic water bodies.

[0163] 3. Broad application prospects: This ecological remediation method has the advantages of environmental protection and economy. It can effectively solve the pollution problem of eutrophic water bodies, restore the ecological balance of water bodies, and has broad application prospects in the remediation of eutrophic water bodies such as urban landscape water bodies, small lakes, and rivers.

[0164] The above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above respective embodiments, the present invention is not limited to the above specific implementation manners. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and their improvements that do not depart from the spirit and scope of the invention are covered by the scope of the claims of the present invention.

Claims

1. An ecological restoration method for eutrophic water bodies by using microorganisms to enhance plant restoration, characterized in that: The following steps are involved: Step 1, screening and cultivation of microbial strains: Collect samples from eutrophic water bodies and their sediments, and screen strains of Bacillus, Pseudomonas and Rhodococcus with high efficiency in nitrogen and phosphorus removal; inoculate the screened strains into corresponding liquid culture medium for cultivation, and adjust the bacterial solution concentration to 1×10 8 CFU / mL; Step 2, preparation of a microbial composite agent: mixing cultured bacterial solutions of Bacillus, Pseudomonas and Rhodococcus in a volume ratio of 1:1:1 to prepare a microbial composite agent; Step 3, selection and pretreatment of aquatic plants: select calamus, reed and canna as aquatic plants, select healthy and uniform seedlings, rinse them with clean water, soak them in a 0.1% potassium permanganate solution for disinfection for 10-15 minutes, and then rinse them with clean water for later use; Step 4, construction of ecological restoration system: set up a polyethylene planting floating bed in the eutrophic water body, with the spacing between planting holes of the floating bed being 20-30cm; plant the pretreated calamus, reed and canna seedlings on the floating bed in a ratio of 1:1:1, with one seedling planted in each planting hole; evenly place microbial composite inoculants around the floating bed after the aquatic plants are planted, with the amount of microbial composite inoculants being 10L / mu; Step 5. Monitoring and management of the restoration process: Regularly monitor water quality indicators such as total nitrogen, total phosphorus, chemical oxygen demand, dissolved oxygen, etc., with a monitoring cycle of once a week; according to the monitoring results, adjust the amount of microbial compound agents added and the growth conditions of aquatic plants in a timely manner. If the nitrogen and phosphorus content in the water body is still high, add microbial compound agents again every 15-20 days, with a release amount of 5L / mu, and remove dead aquatic plants and floating objects in time.

2. The method for ecological restoration of eutrophic water bodies by using microorganisms to enhance plant restoration according to claim 1, characterized in that: The culture conditions of the Bacillus strain are 30° C. and 180 r / min for 24 hours.

3. The method for ecological restoration of eutrophic water bodies by using microorganisms to enhance plant restoration according to claim 2, characterized in that: The culture conditions of the Pseudomonas strain are 28° C. and 160 r / min for 36 hours.

4. The ecological restoration method of eutrophic water body by using microorganisms to enhance plant restoration according to claim 3 is characterized in that: The culture conditions of the Rhodococcus strain are 25° C. and 150 r / min for 48 hours.

5. The method for ecological restoration of eutrophic water bodies by using microorganisms to enhance plant restoration according to claim 4, characterized in that: The planting floating bed is made of polyethylene and has good buoyancy and stability.

6. The method for ecological restoration of eutrophic water bodies by using microorganisms to enhance plant restoration according to claim 5, characterized in that: The temperature of clean water used for washing in the pretreatment of aquatic plants is 23°-26°, and the number of washing times is 2-4 times.

7. The method for ecological restoration of eutrophic water bodies by using microorganisms to enhance plant restoration according to claim 6, characterized in that: The planting ratio of the aquatic plants calamus, reed and canna is 1:1:

1.

8. The method for ecological restoration of eutrophic water bodies by using microorganisms to enhance plant restoration according to claim 7, characterized in that: The amount of microbial compound agent added is 10L / mu, and the subsequent additional amount is 5L / mu.

9. The ecological restoration method of eutrophic water body by using microorganisms to strengthen phytoremediation according to claim 8, characterized in that: The monitoring cycle for water quality indicators is once a week.

10. The ecological restoration method of eutrophic water body by using microorganisms to enhance plant restoration according to claim 9, characterized in that: The nitrogen and phosphorus content in the water body is still high, and microbial compound agents are added again every 15-20 days.

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