A resource utilization method and application of saline-alkali land farmland irrigation wastewater

Abstract

The present invention relates to the field of agricultural hydroponics technology, and in particular to a method and application for resource utilization of saline-alkali farmland irrigation wastewater, comprising the following steps: pre-treating the farmland irrigation wastewater and adjusting the pH; adding nitrogen-fixing fish algae, protein core chlorella and chromococcus separated from the seawater aquaculture drainage outlet obtained by a conventional microalgae separation and purification method to the farmland irrigation wastewater after adjusting the pH; culturing, collecting microalgae after culturing, and obtaining treated farmland irrigation wastewater; adding urea, ammonium dihydrogen phosphate and ED-TA sodium iron salt to the treated farmland irrigation wastewater, and obtaining hydroponic water for pepper hydroponic seedlings. The present invention realizes the resource utilization of farmland irrigation wastewater in the alkali drainage channel, reduces the processing cost; alleviates the pressure on agricultural water resources; prevents soil salinization; reduces the cost of hydroponic seedlings, promotes the growth of pepper seedlings, and improves the survival rate of hydroponic seedlings.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural hydroponics, and in particular to a resource utilization method and application of saline-alkali farmland irrigation wastewater. Background Art

[0002] In recent decades, one of the ways to control salinization in agricultural areas is to use flood irrigation in winter to wash and drain salt from the land. This not only consumes a lot of water resources, but also discharges a lot of concentrated water. Although this measure has promoted the control of salinization in irrigation areas, since natural rivers are often the lowest in terrain and the outlet for drainage, it causes the salinization of river water and wastes precious water resources. The amount of water discharged from farmland each year is equivalent to 1 / 2 of the irrigation water. This part of the discharged water is not treated at all, but discharged into a specific canal, commonly known as the alkali drainage canal. Since the water in the alkali drainage canal is untreated farmland irrigation wastewater after irrigating farmland, it is also called alkali-pressed water. The water contains a large amount of macroelements such as nitrogen, phosphorus and potassium, as well as medium and trace elements, and also contains a variety of inorganic and organic carbon sources. These nutrients are wasted with drainage. Therefore, how to realize the resource utilization of agricultural farmland irrigation wastewater and reduce its treatment cost has become an important problem that needs to be solved urgently.

[0003] Microalgae are low-level autotrophic organisms with tiny individuals, simple structures, and high photosynthetic utilization. They are widely distributed in different habitats such as soil, oceans, rivers, and lakes, and even live in some extreme environments. Microalgae require macroelements, secondary elements, trace elements, and a variety of carbon sources during their growth. In addition, microalgae can release a variety of substances that promote the growth of pepper seedlings during their growth, such as plant hormones, proteins, lipids, and polysaccharides. There are existing technologies for using microalgae for plant cultivation.

[0004] Chinese patent 201510078413.6 provides an ecological hydroponic method based on crop-algae symbiosis. The patent uses the photosynthesis of green algae to increase the oxygen content in the nutrient solution and reduce the cost of hydroponic production. However, the patent does not target pepper seedlings. Peppers have shallow roots and require more dissolved oxygen when hydroponically cultivated. The dissolved oxygen provided by the photosynthesis of green algae alone may not meet the growth needs of peppers. In addition, green algae is a broad concept, and the properties of different types of green algae vary greatly. The inventors have found through experiments that not all green algae are suitable for pepper hydroponic seedlings. Some green algae have too high growth rates and absorb nutrients too quickly, which may compete with pepper seedlings, which is not conducive to the growth of pepper seedlings and increases the input cost of nutrients. The patent uses its own hydroponic nutrient solution, does not involve the resource utilization of farmland irrigation wastewater, and has a high cost. The microalgae used are all microalgae in fresh water and cannot quickly adapt to saline water.

[0005] Therefore, it is very necessary to design a technology that can combine seawater microalgae with the resource utilization of saline-alkali farmland irrigation wastewater, which can achieve the resource utilization of saline-alkali farmland irrigation wastewater while also generating certain economic and ecological benefits. Summary of the invention

[0006] The purpose of the present invention is to provide a method and application for resource utilization of saline-alkali land farmland irrigation wastewater, which combines the microalgae separated from the seawater aquaculture discharge port with the resource utilization of farmland irrigation wastewater, can realize the resource utilization of farmland irrigation wastewater and also produce certain economic and ecological benefits.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The present invention provides a method for resource utilization of farmland irrigation wastewater, comprising the following steps:

[0009] (1) Pre-treat agricultural irrigation wastewater and adjust pH;

[0010] (2) adding nitrogen-fixing Anabaena, Chlorella pyrenoidosa and Chromococcus separated from the marine aquaculture outlet to the farmland irrigation wastewater after pH adjustment in step (1);

[0011] (3) Cultivating the farmland irrigation wastewater to which the microalgae are added in step (2), collecting the microalgae after the cultivation is completed, and obtaining treated farmland irrigation wastewater;

[0012] (4) After adding urea, ammonium dihydrogen phosphate and ED-TA sodium iron salt to the farmland irrigation wastewater treated in step (3), hydroponic water that can be used for hydroponic cultivation of pepper seedlings or irrigation water for conventional seedling cultivation is obtained.

[0013] Furthermore, in step (1), the concentration of each ion in the farmland irrigation wastewater ranges from Na + 0.094~0.158g / L, K + 0.012~0.089 g / L, Ca 2+ 0.265~2.5 g / L, Mg 2+ 0.668~8.82 g / L, HCO3 - 0.019~0.025 g / L, CO3 2- 0.420~0.903 g / L, NO3 - 0.046~0.092 g / L, HPO4 2-0.029~0.268 g / L; the pretreatment method is to simply filter the large impurities in the farm irrigation wastewater, then add 60 mg of sodium hypochlorite per liter and let it stand for 24 hours, and then add 0.07 g of sodium thiosulfate per liter to the farm irrigation wastewater after standing and aerate for more than 8 hours.

[0014] Furthermore, in step (1), the pH is adjusted to adjust the pH of the farmland irrigation wastewater to 6.5-7.5.

[0015] Furthermore, in step (2), the amount of the nitrogen-fixing Anabaena added is 0.1-0.9 g / L, and the amount of the pyrenoid Chlorella added is 1-8×10 5 The amount of the chromococcus algae added is 1-8×10 5 Pieces / L.

[0016] Furthermore, in step (3), the culture conditions are: the light intensity is 160 μmol·m -2 ·s -1 , photoperiod of 16h / 8h (day / night), temperature of 28±2℃ / 18±2℃ (day / night); the method for collecting microalgae is to measure the conductivity every 2 days, and when the conductivity of the agricultural irrigation wastewater drops below 600 µS / cm, 3 / 5-4 / 5 of the mixed microalgae are collected by filtration or centrifugation.

[0017] Furthermore, in step (4), the amount of urea added is 140-300 mg / L, the amount of ammonium dihydrogen phosphate added is 70-75 mg / L, and the amount of ED-TA sodium iron salt added is 1.0-2.0 mg / L.

[0018] The present invention also provides hydroponic water for growing pepper seedlings in water by using the resource utilization method, characterized in that the hydroponic water comprises nitrogen-fixing Anabaena, Chrococcus and Chlorella pyrenoidosa at a concentration of 0.1-0.9 g / L, and the concentrations of nitrogen-fixing Anabaena, Chrococcus and Chlorella pyrenoidosa in the hydroponic water are all ≥1×10 5 Pieces / L.

[0019] The present invention also provides a method for hydroponic cultivation of pepper seedlings, which comprises the step of using the hydroponic water to perform hydroponic cultivation of seedlings. During the hydroponic cultivation of seedlings, aeration is performed for 5-10 minutes every 5-7 days, and the conductivity is measured every 2 days. When the conductivity of the hydroponic water drops below 400 µS / cm, the hydroponic water is used to perform a water change operation.

[0020] The present invention also provides a mixture that can be used for planting peppers in soil or for preparing microalgae fertilizers. The mixture is prepared by mixing the microalgae collected in the step (2) and the wastewater replaced during the water replacement operation.

[0021] The present invention also provides the resource utilization method, the hydroponic water, the pepper hydroponic seedling cultivation method, or the use of the mixture in the treatment and utilization of farmland irrigation wastewater.

[0022] The beneficial effects of the present invention are:

[0023] The seawater microalgae screened by the present invention can release certain active substances that promote the growth of pepper seedlings during their growth, and their photosynthesis can absorb carbon dioxide produced by the respiration of pepper seedlings and produce oxygen. Thereby increasing the dissolved oxygen content in the nutrient solution, preventing the pepper seedlings from dying due to insufficient oxygen content in the nutrient solution. The microalgae screened by the present invention can also combine with plant roots to promote plant growth, and the nitrogen-fixing cyanobacteria and chromococcus in cyanobacteria play a particularly obvious role in nitrogen fixation, which can convert nitrogen in the air into bioavailable N-containing substances. In addition, the microalgae used in the present invention comes from the seawater aquaculture drainage outlet, has a strong adaptability to saline-alkali farmland irrigation wastewater with high salinity, and can also colonize quickly and play a role when subsequently applied in saline-alkali soil.

[0024] The present invention also has the following beneficial effects: (1) it realizes the resource utilization of agricultural irrigation wastewater in the drainage channel and reduces the treatment cost; (2) it alleviates the pressure on agricultural water resources; (3) it prevents soil salinization; (4) it reduces the cost of hydroponic seedlings, promotes the growth of pepper seedlings, and improves the survival rate of hydroponic seedlings and conventional seedlings; (5) the growth of pepper seedlings and microalgae can further absorb the salt of agricultural irrigation wastewater, further reduce the salinity of agricultural irrigation wastewater, and prevent the aggravation of soil salinization after the wastewater is reused; (6) the microalgae cultured in the waste hydroponic solution can continue to be used for the cultivation of peppers in the soil or for the preparation of microalgae fertilizers, thereby generating additional economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a microscope image of microalgae contained in the hydroponic nutrient solution; from left to right, they are Chlorella pyrenoidosa, Anabaena nitrogen-fixing, and Chromococcus;

[0027] Figure 2The stems of each treatment in Example 1 were thick, wherein the egg was Chlorella pyrenoidosa; the solid was nitrogen-fixing Anabaena; the color was Chromococcus;

[0028] Figure 3 The leaf length, leaf width, plant height, and root length of each treatment in Example 1, wherein the egg is Chlorella pyrenoidosa; the solid is Anabaena nitrogen-fixing; the color is Chromococcus;

[0029] Figure 4 is the fresh weight of each treated plant in Example 1, wherein, egg is Chlorella pyrenoidosa; solid is nitrogen-fixing Anabaena; color is Chromococcus;

[0030] Figure 5 Example 1 Chlorophyll content of each treated plant, wherein egg is Chlorella pyrenoidosa; solid is nitrogen-fixing Anabaena; color is Chromococcus;

[0031] Figure 6 The root activity of each treated plant in Example 1, wherein the egg is Chlorella pyrenoidosa; the solid is nitrogen-fixing Anabaena; the color is Chromococcus;

[0032] Figure 7 The stem thickness of each treated plant in Example 2, wherein, U is Chlorella vulgaris; Chlamydomonas mexicana; IV is Scenedesmus quadricauda; Scenedesmus is Scenedesmus;

[0033] Figure 8 The leaf length, leaf width, plant height and root length of each treatment in Example 2, wherein, pu is Chlorella vulgaris; Chlamydomonas mexicana; xi is Scenedesmus quadricauda; Sc is Scenedesmus;

[0034] Fig. 9 is the fresh weight of the plants in each treatment of Example 2, wherein, U is Chlorella vulgaris; Chlamydomonas is Chlamydomonas mexicana; IV is Scenedesmus quadricauda; Scenedesmus is Scenedesmus;

[0035] Fig.10 is the chlorophyll content of each treatment plant in Example 2, wherein, Pu is Chlorella vulgaris; Chlamydomonas is Chlamydomonas mexicana; Four is Scenedesmus quadricauda; Scenedesmus is Scenedesmus;

[0036] Fig.11 is the root activity of each treatment plant in Example 2, wherein, U is Chlorella vulgaris; Chlamydomonas is Chlamydomonas mexicana; IV is Scenedesmus quadricauda; Scenedesmus is Scenedesmus;

[0037] Fig.12 Take a picture of the fruit in Example 3;

[0038] Fig.13 Take a picture of the pepper plants in Example 3. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below, and the embodiments are intended to explain the present invention and should not be construed as limiting the present invention. If specific techniques or conditions are not specified in the embodiments, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications. If the manufacturers of reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0041] Microscopic images of Chlorella pyrenoidosa, Anabaena nitrogen-fixing and Chromococcus used in the present invention are as follows: Figure 1 shown. Example 1

[0042] The farmland irrigation wastewater used in this example was taken from the alkali drainage canal in Bohu County, Bayinguoleng Autonomous Prefecture, and the collection time was February 2024. The concentration range of each ion in the water is Na + 0.094~0.158 g / L, K + 0.012~0.089 g / L, Ca 2+ 0.265~2.5 g / L, Mg 2+ 0.668~8.82 g / L, HCO3 - 0.019~0.025 g / L, CO3 2- 0.420~0.903 g / L, NO3 - 0.046~0.092 g / L, HPO4 2- 0.029~0.268 g / L.

[0043] The method for processing farmland winter irrigation and drainage in this embodiment comprises the following steps:

[0044] (1) Collect farmland irrigation wastewater from the drainage canal and filter out large impurities by simple filtration. Add 60 mg of sodium hypochlorite per liter of farmland irrigation wastewater from the drainage canal and let it stand for 24 hours. Add 0.07 g of sodium thiosulfate to the standing farmland irrigation wastewater and aerate for more than 8 hours.

[0045] (2) measuring the pH of the agricultural irrigation wastewater obtained in step (1), and adjusting the pH to 6.5-7.5 with acetic acid;

[0046] (3) Add 0.1-0.9 g of nitrogen-fixing Anabaena and 1×10 8 Chlorella pyrenoidosa and 1×10 8 Chromococcus;

[0047] (4) The agricultural irrigation wastewater with microalgae added in step (3) was placed under a light intensity of 160 μmol·m -2 ·s -1 , the culture was carried out under the conditions of 16h / 8h (day / night) light cycle and 28±2℃ / 18±2℃ (day / night);

[0048] (5) The conductivity is measured every 2 days. When the conductivity of the agricultural irrigation wastewater drops below 600 µS / cm, 3 / 5-4 / 5 of the mixed microalgae are collected by filtration or centrifugation to obtain the treated agricultural irrigation wastewater.

[0049] (6) After adding 140-300 mg of urea, 70-75 mg of diammonium phosphate, and 1.0-2.0 mg of ED-TA sodium iron salt per liter to the treated farmland irrigation wastewater obtained in step (5), hydroponic water that can be used for hydroponic cultivation of pepper seedlings is obtained.

[0050] Test Example 1

[0051] The pepper seeds were germinated; the hydroponic water prepared in Example 1 was added to four groups of cultivation containers (each group had 3 transparent containers), and the germinated peppers were planted in a planting basket with a sponge for hydroponic seedling cultivation. When the seedlings were hydroponic, aeration was performed for 5-10 minutes every 5-7 days, and the conductivity was measured every 2 days. When the conductivity of the hydroponic water dropped below 400 μS / cm, the water was changed.

[0052] A control group using untreated farmland irrigation wastewater for seedling cultivation, an experimental group containing nitrogen-fixing Anabaena, an experimental group containing Chrococcus, an experimental group containing Chlorella pyrenoidosa, an experimental group containing nitrogen-fixing Anabaena + Chrococcus, and an experimental group containing nitrogen-fixing Anabaena + Chrococcus + Chlorella pyrenoidosa were set up. The treatment method of the experimental group containing nitrogen-fixing Anabaena + Chrococcus + Chlorella pyrenoidosa was as shown in Example 1. The treatment methods of the other experimental groups were compared with Example 1, except that in step (3), 0.1-0.9 g of nitrogen-fixing Anabaena was added; 1×10 5 Chromococcus; 1×10 5 pyrenoidosa; 0.1-0.9 g of nitrogen-fixing Anabaena and 1×10 5 0.1-0.9 g of nitrogen-fixing Anabaena and 1×10 5 Chlorella pyrenoidosa;

[0053] The results showed that in this test case, the pepper seeds turned black and did not grow when untreated farmland irrigation wastewater was used for seedling cultivation, and the seedling cultivation failed. In the other experimental groups, after about 28 days of cultivation, the pepper seedlings in the nitrogen-fixing Anabaena + Chrococcus + Chlorella group had significantly higher plant height, stem thickness, root length, fresh weight, leaf length and leaf width than those in the other experimental groups; the root activity, SPAD value and chlorophyll content of the nitrogen-fixing Anabaena + Chrococcus + Chlorella group were also significantly higher than those of the control group. The specific results are as follows Figure 2-7 As shown. This shows that the nutrient solution of the experimental group can significantly promote the growth of pepper seedlings, promote the development of its root system and the absorption and utilization of nutrients. At the end of the experiment, each experimental group contained 2.56±0.25 g / L of Chromococcus; 1.22±0.09 g / L of Chlorella pyrenoidosa; 2.59±0.21 g / L of nitrogen-fixing Anabaena; 3.62±0.35 g / L of nitrogen-fixing Anabaena + Chlorella pyrenoidosa; 3.96±0.41 g / L of nitrogen-fixing Anabaena + Chromococcus; 4.86±0.26 g / L of nitrogen-fixing Anabaena + Chlorella pyrenoidosa + Chromococcus. Example 2

[0054] The farmland irrigation wastewater used in this example was taken from the alkali drainage canal in Bohu County, Bayinguoleng Autonomous Prefecture, and the collection time was February 2024. The concentration range of each ion in the water is Na + 0.094~0.158 g / L, K + 0.012~0.089 g / L, Ca 2+ 0.265~2.5 g / L, Mg 2+ 0.668~8.82 g / L, HCO3 - 0.019~0.025 g / L, CO3 2- 0.420~0.903 g / L, NO3 - 0.046~0.092 g / L, HPO4 2- 0.029~0.268 g / L.

[0055] (1) Collect farmland irrigation wastewater from the drainage canal and filter out large impurities by simple filtration. Add 60 mg of sodium hypochlorite per liter of farmland irrigation wastewater from the drainage canal and let it stand for 24 hours. Add 0.07 g of sodium thiosulfate to the standing farmland irrigation wastewater and aerate for more than 8 hours.

[0056] (2) measuring the pH of the agricultural irrigation wastewater obtained in step (1), and adjusting the pH to 6.5-7.5 with acetic acid;

[0057] (3) Add 1×10 8 Chromococcus;

[0058] (4) placing the agricultural irrigation wastewater with microalgae added in step (3) under the conditions of a light intensity of 160 μmol·m-2·s-1, a light cycle of 16h / 8h (day / night), and a temperature of 28±2℃ / 18±2℃ (day / night) for cultivation;

[0059] (5) Measure the conductivity every 2 days. When the conductivity of the agricultural irrigation wastewater drops below 600 µS / cm, collect 3 / 5-4 / 5 of the mixed microalgae by filtration or centrifugation to obtain the treated agricultural irrigation wastewater;

[0060] (6) Add 140-300 mg of urea, 70-75 mg of diammonium phosphate, and 1.0-2.0 mg of ED-TA sodium iron salt per liter to the hydroponic water obtained in step (5) to obtain hydroponic water that can be used for growing pepper seedlings in hydroponics.

[0061] Test Example 2

[0062] The pepper seeds were germinated; the hydroponic water prepared in Example 2 was added to four groups of cultivation containers (each group had 3 transparent containers), and the germinated peppers were placed in a planting basket with a sponge for hydroponic seedling cultivation. When the hydroponic seedlings were cultivated, aeration was performed for 5-10 minutes every 5-7 days, and the conductivity was measured every 2 days. When the conductivity of the hydroponic water dropped below 400 μS / cm, the water was changed.

[0063] A control group using untreated farmland irrigation wastewater for seedling cultivation, an experimental group containing Chlorella vulgaris, an experimental group containing Chlamydomonas mexicana, an experimental group containing Scenedesmus quadricauda, ​​and an experimental group containing Scenedesmus spp. were set up. The treatment methods of the above experimental groups were different from those of Example 2, except that in step (3), 1×10 5 Chlorella vulgaris; 1×10 5 Mexican Chlamydomonas; 1×10 5 Scenedesmus quadricauda; 1×10 5 Scenedesmus;

[0064] The results showed that in this test example, when untreated farmland irrigation wastewater was used for seedling cultivation, the pepper seeds turned black and did not grow, and the seedling cultivation failed. After about 28 days of cultivation in the other experimental groups, the growth indicators of pepper seedlings in the experimental group containing common Chlorella, the experimental group containing Chlamydomonas mexicana, the experimental group containing Scenedesmus quadricauda, ​​and the experimental group containing Scenedesmus quadricauda were different. Among them, the growth, chlorophyll content, and root activity of pepper seedlings in the experimental group containing common Chlorella, the experimental group containing Chlamydomonas mexicana, and the experimental group containing Scenedesmus quadricauda were lower than those in the experimental group containing nitrogen-fixing Anabaena + Chlorella pyrenoidosa + Chromococcus in Example 1, as shown in FIG. Figure 8-11At the end of the experiment, the experimental groups contained 1.39±0.07 g / L of Chlorella vulgaris, 1.84±0.11 g / L of Chlamydomonas mexicana, 1.62±0.20 g / L of Scenedesmus quadricauda, ​​and 1.11±0.10 g / L of Scenedesmus. When the solution was changed on the 28th day without aeration, the dissolved oxygen content in the nutrient solution containing Chlorella vulgaris, Chlamydomonas mexicana, Scenedesmus quadricauda, ​​and Scenedesmus was 5.73±0.45, 5.37±0.64, 5.77±0.06 mg / L, and 5.06±0.32 mg / L, respectively.

[0065] Conclusion: Combining Example 1 and Example 2, it can be seen that the treated farmland irrigation wastewater containing different microalgae has different effects on the growth of pepper seedlings. Among them, the farmland irrigation wastewater treated with nitrogen-fixing Anabaena + Chromococcus + Chlorella pyrenoidosa provided in Example 1 of the present invention for pepper seedling cultivation can significantly promote the growth of pepper seedlings and the absorption and utilization of nutrients. Example 3

[0066] The farmland irrigation wastewater used in this example was taken from the alkali drainage canal in Bohu County, Bayinguoleng Autonomous Prefecture, and the collection time was February 2024. The concentration range of each ion in the water is Na + 0.094~0.158 g / L, K + 0.012~0.089 g / L, Ca 2+ 0.265~2.5 g / L, Mg 2+ 0.668~8.82 g / L, HCO3 - 0.019~0.025 g / L, CO3 2- 0.420~0.903 g / L, NO3 - 0.046~0.092 g / L, HPO4 2- 0.029~0.268 g / L.

[0067] (1) Collect farmland irrigation wastewater from the drainage canal and filter out large impurities by simple filtration. Add 60 mg of sodium hypochlorite per liter of farmland irrigation wastewater from the drainage canal and let it stand for 24 hours. Add 0.07 g of sodium thiosulfate to the standing farmland irrigation wastewater and aerate for more than 8 hours.

[0068] (2) measuring the pH of the agricultural irrigation wastewater obtained in step (1), and adjusting the pH to 6.5-7.5 with acetic acid;

[0069] (3) Add 0.1-0.9 g or 1×10 5 0.1-0.9 g or 1×10 5Chromococcus, 0.1-0.9 g or 1×10 5 Chlorella pyrenoidosa;

[0070] (4) placing the agricultural irrigation wastewater with microalgae added in step (3) under the conditions of a light intensity of 160 μmol·m-2·s-1, a light cycle of 16h / 8h (day / night), and a temperature of 28±2℃ / 18±2℃ (day / night) for cultivation;

[0071] (5) Measure the conductivity every 2 days. When the conductivity of the agricultural irrigation wastewater drops below 600 µS / cm, collect 3 / 5-4 / 5 of the mixed microalgae by filtration or centrifugation to obtain the treated agricultural irrigation wastewater;

[0072] (6) Add 140-300 mg of urea, 70-75 mg of diammonium phosphate, and 1.0-2.0 mg of ED-TA sodium iron salt per liter to the farmland irrigation wastewater obtained in step (5) to obtain hydroponic water that can be used for hydroponic cultivation of pepper seedlings.

[0073] (7) adding the hydroponic water obtained in step (6) into a transparent container and performing hydroponic cultivation of pepper seedlings;

[0074] (8) Aeration for 5-10 minutes every 5-7 days during hydroponics;

[0075] (9) Measure the conductivity every 2 days. When the conductivity of the hydroponic water drops below 400 µS / cm, replace the water with the hydroponic water obtained in step (6);

[0076] (10) The wastewater replaced in step (9) is collected and mixed with the microalgae in step (5), and the resulting mixture is further used for growing peppers in the soil or for preparing microalgae fertilizer.

[0077] Test Example 3

[0078] The mixture obtained in Example 3 was used in pepper planting at an application rate of 1 L / mu and was applied 4 times during the entire planting cycle. The differences between the final indicators obtained and those of the control group are shown in Table 1.

[0079] Table 1 Effect of the mixture obtained in Example 3 on the size, weight and yield of pepper fruit

[0080] From Table 1 and Figure 12-13 It can be seen that compared with the control group, the pepper fruits applied with the present invention are significantly larger and the yield can be increased by 18-20%.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be covered by the scope of the claims of the present invention.

Claims

1. A method for resource utilization of farmland irrigation wastewater, characterized in that: The following steps are involved: (1) Pre-treat agricultural irrigation wastewater and adjust pH; (2) adding nitrogen-fixing Anabaena, Chlorella pyrenoidosa and Chromococcus separated from the marine aquaculture outlet to the farmland irrigation wastewater after pH adjustment in step (1); (3) Cultivating the farmland irrigation wastewater to which the microalgae are added in step (2), collecting the microalgae after the cultivation is completed, and obtaining treated farmland irrigation wastewater; (4) adding urea, ammonium dihydrogen phosphate and ED-TA sodium iron salt to the farmland irrigation wastewater treated in step (3) to obtain hydroponic water for growing pepper hydroponic seedlings or irrigation water for conventional seedling cultivation; In step (1), the concentration range of ions in the farmland irrigation wastewater is Na + 0.094~0.158 g / L, K + 0.012~0.089 g / L, Ca 2+ 0.265~2.5 g / L, Mg 2+ 0.668~8.82 g / L, HCO3 - 0.019~0.025 g / L, CO3 2- 0.420~0.903 g / L, NO3 - 0.046~0.092 g / L, HPO4 2- 0.029~0.268 g / L; the pretreatment method is to simply filter the large impurities in the farmland irrigation wastewater, then add 60 mg of sodium hypochlorite per liter and let it stand for 24 hours, and then add 0.07 g of sodium thiosulfate per liter to the farmland irrigation wastewater after standing and aerate for more than 8 hours; In step (1), the pH is adjusted to adjust the pH of the farmland irrigation wastewater to 6.5-7.5; In step (2), the amount of nitrogen-fixing Anabaena added is 0.1-0.9 g / L, and the amount of pyrenoidosa added is 1-8×10 5 The amount of the chromococcus algae added is 1-8×10 5 pcs / L; In step (3), the culture conditions are: the light intensity is 160 μmol·m -2 ·s -1 , photoperiod of 16h day / 8h night, temperature of 28±2℃ day / 18±2℃ night; the method of collecting microalgae is to measure the conductivity every 2 days, and when the conductivity of the agricultural irrigation wastewater drops below 600 µS / cm, 3 / 5-4 / 5 of the mixed microalgae are collected by filtration or centrifugation.

2. The resource utilization method according to claim 1, characterized in that: In step (4), the amount of urea added is 140-300 mg / L, the amount of ammonium dihydrogen phosphate added is 70-75 mg / L, and the amount of ED-TA sodium iron salt added is 1.0-2.0 mg / L.

3. A method for growing pepper seedlings in water, characterized in that: The pepper hydroponic seedling method comprises the step of using the hydroponic water described in claim 1 to perform hydroponic seedling cultivation. During the hydroponic seedling cultivation, aeration is performed for 5-10 minutes every 5-7 days, and the conductivity is measured every 2 days. When the conductivity of the hydroponic water drops below 400 µS / cm, the hydroponic water described in claim 1 is used to perform a water replacement operation.

Images