Method for purifying polluted water area by using bioremediation technology

Abstract

The invention relates to a method for purifying a polluted water area by using a bioremediation technology, which utilizes the biological characteristics of watercress that the watercress is easy to cultivate, high in survival rate, rapid in growth, huge in yield, developed in root system and the like in the water area, and treats water area pollution by cultivating and harvesting the watercress in the polluted water area and converting the harvested watercress into biomass fuel particles. According to the method for purifying the polluted water area through the bioremediation technology, the bioremediation technology is adopted, the biological characteristics of watercress are used for purifying the polluted water area, compared with methods such as chemical remediation, secondary pollution cannot be generated, the method conforms to the pollution treatment thought that people and the nature are harmonious, the self-purification capacity of the nature is enhanced, and the pollution treatment effect is improved. The harvested watercress is converted into biomass fuel particles, resource recycling is achieved, water area pollution is treated, biomass fuel capable of being used for power generation or heat supply is obtained, the utilization efficiency of resources is improved, and good economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of water pollution control, and in particular relates to a method for purifying polluted waters using bioremediation technology. Background Art

[0002] With the rapid development of industrialization and the surge in population, more and more industrial and domestic wastewater, as well as other pollutants, are being discharged into water bodies, leading to increasingly serious water pollution problems worldwide. The situation in my country is also not optimistic. According to relevant statistics, the discharge of wastewater and sewage in my country has increased year by year. Large amounts of untreated sewage are directly discharged into water bodies, causing varying degrees of pollution in rivers, lakes, reservoirs and other water bodies.

[0003] Water pollution poses numerous hazards. Regarding its impact on human health, polluted water can enter the body through drinking water and the food chain, causing acute or chronic poisoning. In industrial and agricultural production, polluted water requires increased treatment costs, resulting in a waste of resources and energy. The food industry has even stricter water requirements; substandard water quality can halt production. Contaminated agricultural irrigation water can also affect the growth and quality of crops.

[0004] At present, the treatment technologies for water pollution mainly include physical methods, chemical methods and bioremediation technologies, but these technologies have certain limitations.

[0005] (1) Physical methods: Common physical methods, such as water diversion and dilution, dilute polluted water bodies through engineering water diversion, so that the water bodies can reach the corresponding water quality standards in a short period of time. However, this method only dilutes the pollutants and does not fundamentally remove the pollutants. It also requires a large amount of water resources and is not suitable for areas with water shortages. In addition, the physical method of dredging sediments controls and reduces the source of black and odorous water by removing the surface polluted sediments. However, this technology is labor-intensive and costly, and will cause certain damage to the water ecosystem.

[0006] (2) Chemical method: The chemical method is to control the components that cause black and odor in water by screening or synthesizing chemical agents. One or several synthetic and safe chemical products are added at a safe and reliable dosage, which can quickly achieve the purpose of alleviating black and odor and can inhibit the black and odor phenomenon for a certain period of time. However, the use of chemical agents may cause secondary pollution, and long-term use may cause imbalance in the water ecosystem.

[0007] (3) Bioremediation technology: Bioremediation technology includes microbial remediation technology, plant remediation technology, animal remediation technology and composite remediation technology. Microbial remediation technology uses microorganisms to degrade pollutants to achieve the purpose of water purification, but microbial remediation preparations are expensive, have a short shelf life, slow action, and are also limited by water environment conditions, making them difficult to use on a large scale; plant remediation technology uses the combined action of plants and their rhizosphere microorganisms to remove pollutants from water bodies, but some plant remediation methods have long growth cycles and need to be harvested regularly, making their actual effects less obvious; animal remediation technology uses the food chain and metabolic effects of aquatic animals to reduce the concentration of pollutants in water bodies, but the effectiveness of this technology is affected by many factors such as the species, number and living environment of the animals; composite remediation technology combines the above-mentioned technologies to give full play to their respective advantages, but in actual application, its technical combination and coordination are more difficult.

[0008] Watercress, also known as water mustard, watercress, and watercress, is a perennial aquatic herb of the genus Watercress in the family Cruciferae. Native to Europe, it possesses many properties suitable for use in water pollution control.

[0009] (1) Growth characteristics: Watercress grows fast, prefers cool and full-sun conditions, has few pests and diseases, and has a strong water requirement. The base of the plant needs to be watered or the soil is completely moist to grow properly and form a clump. A slight drought will hinder its growth. Usually, a water depth of 5 to 10 cm is most suitable for its growth. It is suitable for growing in water, ditches, swamps or paddy fields. During the entire growth period, it is very sensitive to water and can only grow normally when the planting area is flooded. It prefers a cool climate and grows vigorously when the temperature is 15 to 20°C. It grows slowly above 25°C, so it grows rapidly from February to May. Moreover, watercress has a developed branch regeneration ability. The stem nodes take root on the ground to form new plants. It has a strong ability to occupy space and can effectively inhibit the growth of other weeds. In addition, the yield of watercress cultivation is extremely high, with an annual yield of 10,000 kg of fresh grass per mu. The digestible crude protein in the nutrients per unit area is more than 7 times that of rice.

[0010] (2) Enrichment capacity: Studies have shown that aquatic vegetables have strong enrichment capacity, with an average enrichment coefficient of 2 to 150 times for common metal elements, and the average enrichment of rare elements is generally higher than that of terrestrial vegetables. The enrichment coefficient of heavy metal elements is generally around 10 times. As an aquatic vegetable, watercress has a very developed root system that can absorb pollutants in the water body and has a strong ability to resist and remove pollutants. For example, relevant studies have explored the effect of watercress in purifying pig wastewater, and proved that watercress has strong pollution resistance and can adapt to high-concentration biogas slurry and grow well in it. The nutrients in biogas slurry can provide favorable conditions for the rapid growth of watercress. There are also studies that measured the element content in water samples obtained from polluted waters in Switzerland and fresh watercress samples. The results showed that watercress has a good enrichment effect on heavy metal elements such as As, Cu, Zn and other 26 elements, especially P, Mn and Al. It has a strong enrichment effect on Cl, Fe, Si, Ca, S and other elements.

[0011] In summary, existing water pollution control technologies have certain limitations. However, watercress, with its easy cultivation, high survival rate, rapid growth, large yield, well-developed root system, and excellent enrichment of various pollutants, provides a research foundation and application prospects for its use in water pollution control. However, there is currently no mature technology for the large-scale application of watercress in water pollution control and its conversion into biomass fuel pellets, so this invention has important practical significance. Summary of the Invention

[0012] Purpose of the invention: In order to overcome the above shortcomings, the purpose of the present invention is to provide a method for purifying polluted waters using bioremediation technology. The method has a reasonable design and is based on the biological characteristics of watercress that grows in large quantities in waters. The aquatic plant watercress is cultivated in polluted waters according to the local climate. Energy is obtained and the heavy metal elements enriched therein are recovered by utilizing its characteristics of effectively enriching pollution sources and processing it into biomass fuel particles.

[0013] The purpose of the present invention is achieved through the following technical solutions: A method for purifying polluted waters using bioremediation technology utilizes the biological characteristics of watercress in water to cultivate and harvest watercress in polluted waters and convert the harvested watercress into biomass fuel pellets to control water pollution.

[0014] The present invention uses bioremediation technology, utilizing the biological properties of watercress to purify polluted waters. Compared to chemical remediation methods, this method does not produce secondary pollution, conforms to the pollution control concept of harmonious coexistence between humans and nature, and strengthens nature's own self-purification ability. Harvested watercress is converted into biomass fuel pellets, achieving resource recycling. This not only controls water pollution, but also produces biomass fuel that can be used for power generation or heating, improving resource utilization efficiency and achieving good economic and environmental benefits. Watercress has biological properties such as ease of cultivation, high survival rate, rapid growth, large yield, and a well-developed root system. It can adapt to waters of varying degrees and types of pollution, including waters contaminated by organic matter, inorganic matter, and metals, and has a wide range of applications.

[0015] Furthermore, the above-mentioned method of purifying polluted waters using bioremediation technology specifically includes the following steps: S1: Survey the polluted waters, define the volume and extent of pollution, and identify the main pollution sources; S2: Cultivating watercress in polluted waters; S3: Harvest watercress when it reaches 25-30 cm in height, based on its 30-40 day growth cycle. Harvest and replant at least three times within a one-year period, starting from the first planting of watercress in polluted waters. S4: Drying and crushing the mechanically harvested watercress near shore; S5: performing biomass molding processing on the dried and crushed watercress, and hot-pressing the watercress into biomass fuel pellets; S6: Continuously track and monitor the polluted waters, and repeat the above S2 to S5 processes until the polluted waters meet environmental safety requirements.

[0016] In step S1 of the present invention, the polluted waters are surveyed, the volume and extent of the pollution are defined, and the main sources of pollution are determined, which can provide an accurate basis for subsequent governance, make the governance measures more targeted, and improve the governance effect. For example, different pollution sources may require different governance focuses. After clarifying the pollution sources, the enrichment effect of watercress on specific pollutants can be better exerted. Step S3 stipulates the growth cycle and harvesting standards of watercress, as well as the number of harvesting and replanting within a one-year cycle, making full use of the rapid growth characteristics of watercress, harvesting multiple times in a short period of time, increasing the total amount of pollutant enrichment of watercress, and accelerating the process of water pollution control. Step S6 continuously tracks and monitors the polluted waters, and repeats the governance process until the polluted waters meet the environmental safety requirements, ensuring the continuity and effectiveness of governance, and being able to thoroughly solve the water pollution problem.

[0017] Furthermore, in the above-mentioned method of purifying polluted waters using bioremediation technology, in S2, watercress is directly cultivated in polluted waters with a water area of less than 1,000 square meters (such as small rivers, waterways, small pools, small ponds, etc.), and watercress is cultivated in fences after the water surface of polluted waters with a water area of ≥1,000 square meters is divided into areas.

[0018] Different cultivation methods are used depending on the type of polluted water. For small rivers, canals, small ponds, and small pools, cultivating watercress directly is simple and convenient. For other waters, cultivating watercress in fenced areas can better control its growth range, prevent its uncontrolled spread, and facilitate management and harvesting.

[0019] Furthermore, in the above-mentioned method of purifying polluted waters using bioremediation technology, in S2 and S3, the cultivation cycle of watercress depends on the local climate of the polluted waters, and watercress is cultivated when the ambient temperature is ≥10°C, and cultivation of watercress is stopped when the ambient temperature is ≤0°C.

[0020] Considering the growth habits of watercress, it prefers cool climates, growing vigorously between 15°C and 20°C, but slowing down above 25°C. Determining the cultivation cycle based on local climatic conditions allows watercress to grow in a suitable environment, improving its survival rate and growth rate, thereby further enhancing its role in purifying waters. Cultivating watercress in low-temperature environments, where it is unsuitable for growth, avoids resource waste and reduces management costs.

[0021] Furthermore, in the above-mentioned method of purifying polluted waters using bioremediation technology, the moisture content of the dried watercress is controlled at 5-10%.

[0022] Preferably, the moisture content of the dried watercress is controlled at 5%. Keeping the moisture content of the dried watercress at approximately 5% facilitates subsequent biomass molding. Excessively high moisture content can affect the hot pressing process, leading to unstable biomass fuel pellet quality. However, an appropriate moisture content allows the watercress to better blend with other biomass feedstocks and form a compact structure during the hot pressing process, improving the density and strength of the biomass fuel pellets.

[0023] Furthermore, in the above-mentioned method of purifying polluted waters using bioremediation technology, the specific steps of drying and crushing the harvested watercress are as follows: (1) Using a screw extrusion dehydrator to dehydrate fresh watercress, removing 60-70% of the water, and then collecting the water and discharging it into the water where the watercress was picked; (2) The squeezed watercress is mechanically crushed multiple times to a size of 5 to 6 cm; it is dried using a stirring electric drying device or a multi-layer electric drying box to continue to remove the remaining moisture in the watercress.

[0024] Preferably, a screw extrusion dehydrator is used to perform screw extrusion dehydration on the fresh watercress to remove 70% of the water.

[0025] Furthermore, in the above-mentioned method for purifying polluted waters using bioremediation technology, in S5, the dried and crushed watercress and the biomass raw material are mixed, and then an organic binder is added, and then a biomass pelletizer is used to hot-press and shape the mixed watercress into biomass fuel pellets.

[0026] Mixing dried and crushed watercress with other high-calorific biomass feedstocks can fully leverage the strengths of different biomass feedstocks, improving the calorific value and combustion performance of biomass fuel pellets. Adding an organic binder can enhance the molding effect of biomass fuel pellets, giving them greater strength and stability, making them easier to store and transport.

[0027] Furthermore, in the above-mentioned method of purifying polluted waters using bioremediation technology, in S5, the biomass raw materials include but are not limited to agricultural waste, agricultural product processing residues, agricultural product processing waste liquid, forestry waste, aquatic biomass and animal waste, and the organic binder includes but is not limited to waste liquid rich in sulfonate lignin, sulfite and lignin sulfonate generated by the papermaking industry and agricultural and forestry waste rich in starch and pectin.

[0028] Using waste liquid from the papermaking industry and agricultural and forestry waste as organic binders achieves resource utilization, reduces environmental pollution, and lowers the production cost of biomass fuel pellets. These organic binders are widely available, low-cost, and have excellent bonding properties. They can improve economic and environmental benefits while ensuring the quality of biomass fuel pellets.

[0029] Furthermore, in the above-mentioned method of purifying polluted waters using bioremediation technology, in said S5, a biomass burner is used to fully burn the above-mentioned biomass fuel particles, the heat generated is used for power generation or heating, and the high-temperature flue gas generated is recovered for waste heat and then safely discharged after being dried and purified.

[0030] The heat generated by burning biomass fuel pellets is used for power generation or heating, achieving energy recycling and reducing dependence on traditional energy sources, with good energy and economic benefits. The waste heat from high-temperature flue gas is recovered and then dried and purified before safe discharge, reducing the emission of harmful substances in the flue gas and reducing pollution to the atmospheric environment, thus meeting environmental protection requirements.

[0031] The term "full combustion" refers to any one or more of the following: 1. The combustion efficiency of biomass fuel pellets is >80%; 2. The calorific value of biomass fuel pellets is high; 3. The ash content of biomass fuel pellets should be as low as possible, generally required to be below 3%; 4. The volatile matter content of biomass fuel pellets is generally required to be between 70% and 85%; 5. The moisture content of biomass fuel pellets is less than 10%; 6. Environmental protection requirements require that pollutant emissions be minimized. For example, the sulfur content in the exhaust gas emitted after the biomass fuel pellets are fully burned should be less than 0.38%.

[0032] Furthermore, in the above-mentioned method for purifying polluted waters using bioremediation technology, in S5, the ash produced after combustion is collected, and then heavy metals are extracted and recovered.

[0033] The ash produced after combustion is collected and sent to a professional company with heavy metal extraction and recovery qualifications for heavy metal extraction and recovery. This achieves secondary utilization of heavy metal resources, improves resource utilization efficiency, and reduces resource waste. Recovering heavy metals from the ash can prevent secondary pollution of soil and water bodies by heavy metals, further protecting the ecological environment.

[0034] Compared with the prior art, the present invention has the following significant improvements and beneficial effects: (1) The method for purifying polluted waters using bioremediation technology disclosed in the present invention has the environmental benefits of efficiently purifying polluted waters, inhibiting weed growth, and avoiding secondary pollution; watercress has biological characteristics such as easy cultivation, high survival rate, rapid growth, huge yield, and a well-developed root system, and can effectively adsorb and enrich pollutants such as organic matter, inorganic matter, and metals in polluted waters. By continuously cultivating and harvesting watercress, the concentration of pollutants in the waters can be gradually reduced until environmental safety requirements are met, thereby achieving effective treatment of polluted waters; watercress has a well-developed branch regeneration ability, and its stem nodes take root on the ground to form new plants. It has a strong ability to occupy space and can form dense grass, which is good for Suppressing the growth of other weeds not only reduces competition between weeds and watercress for nutrients and space, thus facilitating the growth and reproduction of watercress, but also avoids potential pollution to the aquatic environment caused by the use of chemical herbicides, thus maintaining the balance and stability of the aquatic ecosystem. During the harvesting and processing of watercress, a series of measures are taken to avoid secondary pollution. The harvested watercress is dried near the shore to prevent the water and soil carried by the watercress from polluting the surrounding area. During the drying process, a screw extrusion dehydrator is used to remove about 70% of the water, which is then collected and discharged into the waters where the watercress was harvested, thus achieving the recycling of water resources and reducing the impact on the surrounding environment. (2) The method of purifying polluted waters using bioremediation technology disclosed in the present invention has good economic benefits; the yield of watercress cultivation is extremely high, which provides sufficient raw materials for the subsequent production of biomass fuel particles. The harvested watercress is dried, biomass-molded, hot-pressed into biomass fuel particles, and then fully burned using a biomass burner. The heat generated can be used for power generation or heating, realizing energy conversion and utilization; at the same time, the waste heat of the high-temperature flue gas generated is recovered and utilized, further improving energy utilization efficiency; this method of converting watercress into biomass fuel not only solves the problem of watercress processing, but also creates new energy products with high economic value; the ash after combustion is collected and sent to a professional company for extraction and recovery of heavy metals. These heavy metals have certain economic value and can be reused, which not only reduces the potential harm of heavy metals to the environment, but also brings additional economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a scene photo of picking mature watercress in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following is a summary of Example 1 and Example 2 in combination with specific experimental data and the attached Figure 1 , the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0037] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention. The following Example 1 is designed to verify the enrichment effect of watercress on pollutants in polluted waters.

[0038] Example 1 Environmental water samples and watercress samples grown in the water were collected from Le Grand Canal de Villeneuve, Switzerland, to test the watercress's ability to accumulate pollutants. The watercress, which had a growth period of approximately two months, was analyzed and the pollutant detection results are shown in Tables 1 and 2.

[0039] Table 1. Determination results of heavy metal element content Heavy metal elements Content of heavy metal elements in environmental water samples (mg / kg) Content of heavy metal elements in watercress samples (mg / kg) Cd ND ND Hg ND ND As ND 2.34 Pb ND ND Cr ND ND Cu 6.31 12.6 Ni 8.7 8.79 Zn 0.656 52.6 Table 2 Determination results of other element contents Other elements Content of other elements in environmental water samples (mg / kg) Content of other elements in watercress samples (mg / kg) S 147 5232 Si 105 33249 Ca 58.6 10538 Cl 17.2 9560 Fe 6.81 2169 Mn <0.1 2362 Al <0.1 2016 Sr 2.08 134 Zr <0.1 46.2 P <0.1 5076 Ti <0.1 30 Br <0.1 18.7 Ba <0.1 18.4 I <0.1 11 Rb <0.1 6.35 Co <0.1 4.01 Y <0.1 3.72 Table 1 shows that the concentrations of Cd, Hg, As, Pb, and Cr in the original environmental water sample were all below the detection limit and were undetectable. However, in the watercress sample grown in this water sample, As was enriched, reaching a concentration of 2.34 mg / kg.

[0040] Measurements of copper content in natural water samples from around the world show an average copper content of 3 μg / L in freshwater and 0.25 μg / L in seawater. When copper levels reach 0.01 mg / L, it significantly inhibits the water's self-purification process. When copper levels exceed 3.0 mg / L, it produces an unpleasant odor. Copper is highly toxic to aquatic life. Some believe that the toxic concentration of copper for fish begins at 0.002 mg / L, but it is generally considered safe for fish at 0.01 mg / L. Environmental water samples contain as much as 6.31 mg / kg of copper, clearly indicating copper contamination. Watercress grown in these waters, however, contained 12.6 mg / kg of copper, twice the average concentration in the water, demonstrating its ability to accumulate copper.

[0041] The nickel concentration in natural freshwater is approximately 0.5 μg / L, while that in seawater is 0.66 μg / L. The Ni content in environmental water samples reached 8.7 mg / kg, indicating that the waters were Ni-contaminated. However, watercress has a less pronounced Ni accumulation, saturating the waters to a mere 8.79 mg / kg.

[0042] The natural concentration of zinc in freshwater ranges from 5 to 100 μg / L, clearly indicating that the waters were also contaminated with zinc. However, the watercress sample contained a high zinc concentration of 52.6 mg / kg, nearly 80 times the concentration in the waters, demonstrating that watercress is an excellent zinc concentrator.

[0043] The following Example 2 provides a specific implementation method for purifying polluted waters using bioremediation technology.

[0044] Example 2 The specific implementation method of using bioremediation technology to purify polluted waters in Example 2 is as follows: (1) Survey the polluted waters, define the volume and extent of pollution, and identify the main pollution sources; (2) Cultivating watercress directly in polluted waters with an area of less than 1,000 square meters (such as small rivers, watercourses, small pools, small ponds, etc.); and cultivating watercress in fenced areas after dividing the water surface of polluted waters with an area of ≥1,000 square meters; (3) The cultivation cycle of watercress depends on the local climate of the polluted waters. Watercress should be cultivated when the ambient temperature is ≥10°C and stopped when the ambient temperature is ≤0°C (usually in winter). Watercress should be harvested when the seedlings are 25-30 cm tall, based on their 30-40 day growth cycle. Watercress should be harvested and replanted at least three times within a one-year period starting from the first cultivation of watercress in the polluted waters. (4) After the watercress matures, it is harvested mechanically and then dried near the shore to prevent the water / soil carried by the watercress from causing secondary pollution to the surrounding area; (5) Drying the harvested watercress; the first step is to use a screw extrusion dehydrator to screw-extrusion dehydration on the fresh watercress, which can remove about 70% of the water, and the water is then collected and discharged into the water area where the watercress was picked; the second step is to mechanically crush the squeezed watercress several times to make it about 5 cm in size; the last step is to use a stirring electric drying device or a multi-layer electric drying box to dry it, which can continue to remove up to about 25% of the 30% of water remaining in the watercress; the moisture content of the dried watercress is controlled at about 5%; (6) The dried watercress is subjected to biomass molding treatment, and the specific method is to mix the dried and crushed watercress with other high calorific value biomass raw materials (wood processing residues, such as sawdust, wood chips, etc.), and then add an organic binder (waste rich in natural biomass binder components, such as sulfonate lignin, sulfite and lignin sulfonate waste liquid generated by the papermaking industry, and agricultural and forestry waste with high starch and pectin content, etc.), and then use a biomass pelletizer to hot-press and mold it into biomass fuel pellets; wherein the mixing mass ratio of watercress, biomass raw materials, and organic binder is 6:3:1; (7) Using a biomass burner to fully burn the biomass fuel particles prepared above, the heat generated can be used for power generation / heating, and the high-temperature flue gas is recycled for waste heat and then dried and purified before being safely discharged; (8) Collect the ash after combustion and send it to a professional company for extraction and recovery of heavy metals; (9) Continuously track and monitor the pollution of the polluted waters, and repeat the above process of cultivating, harvesting, drying, crushing, and manufacturing biomass fuel pellets of watercress until the polluted waters meet environmental safety requirements.

[0045] The method of purifying polluted waters using bioremediation technology described in the present invention utilizes the biological characteristics of watercress to treat polluted waters, falls within the scope of bioremediation technology, and conforms to the trend of sustainable development. Compared with traditional pollution control technologies, bioremediation technology has the advantages of a wide range of applications, low cost, simple operation, and no secondary pollution, which is conducive to achieving long-term and stable treatment of polluted waters. The present invention combines pollution control with agricultural production, achieving a balance between ecological restoration and economic benefits. By planting watercress in polluted waters, not only is the water quality purified, but also economically valuable biomass fuels and recyclable heavy metals are produced, transforming traditional polluting agriculture into a new type of pollution-purifying agriculture. This model provides new ideas and directions for the sustainable development of agriculture and helps promote the development of ecological agriculture.

[0046] In summary, the method of purifying polluted waters using bioremediation technology described in the present invention has significant beneficial effects in terms of environment, economy, resource utilization and sustainable development, and has broad application prospects and promotion value.

[0047] The present invention has many specific application paths, and the above is only a preferred embodiment of the present invention. It should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, several improvements can be made without departing from the principles of the present invention, and these improvements should also be considered as the scope of protection of the present invention.

Claims

1. A method for purifying polluted waters using bioremediation technology, characterized in that: By utilizing the biological characteristics of watercress in water, watercress is cultivated and harvested in polluted waters, and the harvested watercress is converted into biomass fuel pellets to control water pollution.

2. The method for purifying polluted waters using bioremediation technology according to claim 1, characterized in that: The specific steps include: S1: Survey the polluted waters, define the volume and extent of pollution, and identify the main pollution sources; S2: Cultivating watercress in polluted waters; S3: Harvest watercress when it reaches 25-30 cm in height, based on its 30-40 day growth cycle. Harvest and replant at least three times within a one-year period, starting from the first planting of watercress in polluted waters. S4: Drying and crushing the mechanically harvested watercress near shore; S5: performing biomass molding processing on the dried and crushed watercress, and hot-pressing the watercress into biomass fuel pellets; S6: Continuously track and monitor the polluted waters, and repeat the above S2 to S5 processes until the polluted waters meet environmental safety requirements.

3. The method for purifying polluted waters using bioremediation technology according to claim 2, characterized in that: In the above S2, watercress is directly cultivated in the polluted water area with a water area less than 1000 square meters, and watercress is cultivated in the polluted water area with a water area greater than or equal to 1000 square meters after the water surface is divided into areas.

4. The method for purifying polluted waters using bioremediation technology according to claim 2, characterized in that: In S3, the cultivation cycle of watercress depends on the local climate of the polluted waters. When the ambient temperature is ≥10°C, the watercress is cultivated. When the ambient temperature is ≤0°C, the cultivation of watercress is stopped.

5. The method for purifying polluted waters using bioremediation technology according to claim 2, characterized in that: In the step S4, the moisture content of the dried watercress is controlled to be 5-10%.

6. The method for purifying polluted waters using bioremediation technology according to claim 2, characterized in that: In S4, the specific steps of drying and crushing the harvested watercress are: (1) Using a screw extrusion dehydrator to dehydrate fresh watercress, removing 60-70% of the water, and then collecting the water and discharging it into the water where the watercress was picked; (2) Mechanically crushing the squeezed watercress several times to a size of 5 to 6 cm; Use stirring electric drying equipment or multi-layer electric drying box to dry it and continue to remove the remaining moisture in the watercress.

7. The method for purifying polluted waters using bioremediation technology according to claim 1, characterized in that: In S5, the dried and crushed watercress and the biomass raw material are mixed, and then an organic binder is added, and then a biomass pelletizer is used to hot-press and shape the mixed watercress into biomass fuel pellets.

8. The method for purifying polluted waters using bioremediation technology according to claim 7, characterized in that: In said S5, the biomass raw materials include but are not limited to agricultural waste, agricultural product processing residues, agricultural product processing waste liquid, forestry waste, aquatic biomass and animal waste, and the organic binders include but are not limited to waste liquid rich in sulfonate lignin, sulfite and lignin sulfonate generated by the papermaking industry and agricultural and forestry waste rich in starch and pectin.

9. The method for purifying polluted waters using bioremediation technology according to claim 1, characterized in that: In S5, the biomass fuel particles are fully burned using a biomass burner, and the heat generated is used for power generation or heating. The high-temperature flue gas generated is recycled for waste heat and then dried and purified before being safely discharged.

10. The method for purifying polluted waters using bioremediation technology according to claim 9, characterized in that: In S5, the ash generated after combustion is collected, and then heavy metals are extracted and recovered.

Images