A resource utilization method for high COD wastewater

Abstract

The present invention belongs to the technical field of resource utilization of brewing wastewater, and relates to a method for resource utilization of high-COD wastewater. It comprises the following steps: 1) diluting the high-COD wastewater; 2) adjusting the pH of the diluted wastewater; 3) filtering the wastewater after pH adjustment to obtain water-soluble fertilizer; 4) using the water-soluble fertilizer for planting and cultivating crop products; wherein, the dilution step in step 1) and the pH adjustment step in step 2) are not interchangeable; the high-COD wastewater is wastewater generated during the stacking of lees of sauce-flavored liquor. According to the characteristics of the wastewater, the present invention performs a simple pretreatment on the high-COD wastewater to prepare water-soluble fertilizer, which can be used for the planting of crop products. It uses a relatively low treatment cost, realizes the resource utilization of high-COD wastewater, and the use of water-soluble fertilizer further improves the yield and quality of crops.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of brewing wastewater and relates to a resource utilization method of high-COD wastewater. Background Art

[0002] Brewery wastewater is a highly concentrated organic wastewater, consisting of high-organic-matter concentrations of cellar bottom water, pot bottom water, and rinse water, along with other wastewaters such as lees leachate. It exhibits high COD, low pH, high SS, high ammonia nitrogen, and high phosphorus concentrations. Treatment methods for brewery wastewater include physical, chemical, and biological methods such as adsorption, membrane filtration, and advanced oxidation. While these technologies are relatively mature, they are associated with high treatment costs. Many researchers have also employed novel approaches, such as electrolysis and catalysis, which have shown promising results, but are still relatively inadequate in practical application.

[0003] Fresh distiller's grains refer to the residue left after brewing wine, such as sorghum. They have a high moisture content of about 60%. Wastewater is generated during stacking or storage, and the wastewater contains a large amount of organic matter, high acidity, and a pollutant (COD) concentration of up to 250,000 mg / L. It is highly difficult to treat and will cause serious environmental pollution if not properly treated. Currently, there are many studies on resource-based treatment technologies for distiller's grains, such as using distiller's grains to produce feed, using distiller's grains as fuel, and producing organic fertilizer with distiller's grains. However, there are relatively few studies on the resource utilization of wastewater (distiller's grains leachate) generated during the storage of distiller's grains.

[0004] Regarding the resource recycling of distiller's grains leachate, Chinese patent CN115094006A "A method for resource utilization of distiller's grains leachate" discloses a method for preparing a culture medium for fermenting microbial inoculants using high-concentration wastewater generated during the distiller's grains stacking process. However, preparing high-concentration wastewater into a microbial culture medium requires sterilization treatment, which consumes a lot of energy.

[0005] Based on this, the present invention aims to provide a method for efficiently resource-utilizing high-COD wastewater generated during the storage of distiller's grains. Summary of the Invention

[0006] The present invention aims to provide a method for resource utilization of high-COD wastewater generated during the storage of distiller's grains, which has a high degree of resource utilization and low energy consumption.

[0007] Another object of the present invention is to provide a new use of high-COD wastewater in the preparation of water-soluble fertilizers.

[0008] Water-soluble fertilizers refer to composite fertilizers containing nitrogen, phosphorus, potassium, calcium, magnesium, trace elements, amino acids, humic acid, alginic acid, etc. that can be completely dissolved in water. Based on the nutrient content, there are macronutrient water-soluble fertilizers, medium-nutrient water-soluble fertilizers, trace-nutrient water-soluble fertilizers, amino acid-containing water-soluble fertilizers, humic acid-containing water-soluble fertilizers, organic water-soluble fertilizers, etc. The high COD wastewater generated during the storage of vinasse is rich in nutrients such as nitrogen (N), phosphorus (P), and potassium (K). Based on this, the present invention aims to use the high COD wastewater generated during the storage of vinasse for the production of water-soluble fertilizers. However, the research on the preparation of water-soluble fertilizers using the high COD wastewater generated during the storage of vinasse is still blank. In the process of preparing water-soluble fertilizer using high-COD wastewater, the present invention found that due to the high organic matter content in the high-COD wastewater, microorganisms are easy to grow and reproduce in an open environment, especially when the hydroponic solution is deep, oxygen is consumed quickly, anaerobic bacteria multiply rapidly, the hydroponic solution is easy to stink and pollute the environment, and it is also easy to cause necrosis of plant roots.

[0009] In one aspect, the present invention provides a method for preparing water-soluble fertilizer using high-COD wastewater.

[0010] In some embodiments, the high-COD wastewater is wastewater generated during the stacking of Maotai-flavor liquor lees.

[0011] On the other hand, the present invention also provides a method for resource utilization of high COD wastewater, comprising the following steps:

[0012] 1) Dilution treatment of high COD wastewater;

[0013] 2) adjusting the pH of the diluted wastewater;

[0014] 3) filtering the wastewater after the pH adjustment to obtain a water-soluble fertilizer;

[0015] 4) using the water-soluble fertilizer for cultivating and planting crops;

[0016] Among them, the dilution step in step 1) and the pH adjustment step in step 2) are not interchangeable; the high-COD wastewater is the wastewater generated during the stacking process of Maotai-flavor liquor lees.

[0017] In some embodiments, in step 1), the diluting treatment of the high-COD wastewater includes: adding the high-COD wastewater to water and mixing.

[0018] In some embodiments, the dilution factor is 30-800 times; preferably, the dilution factor is 50-200 times; preferably, the dilution factor is 70-200 times; preferably, the dilution factor is 80-190 times; preferably, the dilution factor is 80-150 times; preferably, the dilution factor is 90-120 times; preferably, the dilution factor is 95-105 times.

[0019] In some embodiments, in step 2), adjusting the pH of the diluted wastewater comprises: adding a pH adjuster to the diluted wastewater to adjust the pH to 5.0-7.0; in step 2), adjusting the pH to 6.1-6.9; preferably, adjusting the pH to 6.3-6.6.

[0020] In some embodiments, the pH adjuster is selected from one or more of calcium magnesium phosphate, sodium bicarbonate, sodium bicarbonate and calcium carbonate; preferably, the pH adjuster is selected from calcium magnesium phosphate.

[0021] In some embodiments, in step 3), the filtering comprises: filtering through six layers of gauze.

[0022] In some embodiments, when used for lettuce seed germination and / or shallow tray hydroponics and / or hydroponics, in step 1), the dilution multiple is 80-150; preferably, the dilution multiple is 90-120.

[0023] In some embodiments, when used for seed germination and / or shallow tray hydroponics and / or hydroponics of lettuce, in step 2), the pH is adjusted to 6.1-6.9; preferably, the pH is adjusted to 6.3-6.6.

[0024] In some embodiments, when used for lettuce planting, in step 1), the dilution multiple is 80-150; preferably, the dilution multiple is 90-120.

[0025] In some embodiments, when used for growing lettuce, in step 2), the pH is adjusted to 5.5-6.9; preferably, the pH is adjusted to 6.0-6.6.

[0026] In some embodiments, when used for wheatgrass seed germination and / or shallow tray hydroponics and / or hydroponics, in step 1), the dilution multiple is 70-200 times; preferably, in step 1), the dilution multiple is 50-100 times.

[0027] In some embodiments, when used for wheatgrass seed germination and / or shallow tray hydroponics and / or hydroponics, in step 2), the pH is adjusted to 5.0-7.0; preferably, in step 2), the pH is adjusted to 6.3-6.7.

[0028] On the other hand, the present invention also provides a water-soluble fertilizer prepared by the method.

[0029] On the other hand, the present invention also provides an application of the method or the water-soluble fertilizer in the field of crop cultivation and planting.

[0030] In some embodiments, the crop cultivation and planting include: lettuce seed germination cultivation, lettuce hydroponics, wheatgrass hydroponics, and lettuce planting.

[0031] On the other hand, a crop cultivation and planting method comprises: adding the water-soluble fertilizer according to claim 8 during the crop seed germination cultivation / or shallow tray hydroponics / or planting process.

[0032] In some embodiments, the crops include lettuce and wheat grass.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] The present invention provides a method for resource utilization of high-COD wastewater, and prepares water-soluble fertilizer through high-COD wastewater. The method takes wastewater generated in the stacking process of high-COD and low-pH distiller's grains as the resource object, adopts different methods for pretreatment according to the characteristics of the wastewater to prepare water-soluble fertilizer, and is used for the cultivation of crop products, thereby realizing the resource utilization of high-COD wastewater, saving treatment costs, avoiding environmental pollution, and improving the yield and quality of crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a comparison chart of the growth of lettuce with and without irrigating base fertilizer in the embodiment of the present invention; Figure 1 (A) is the growth diagram of lettuce irrigated with base fertilizer. Figure 1 (B) is the growth diagram of lettuce without irrigation of base fertilizer;

[0036] Figure 2 This is a comparison chart of the growth of lettuce sprayed with different foliar fertilizers one month after sowing in the embodiment of the present invention; wherein, Figure 2 (A) shows the growth of lettuce sprayed with foliar fertilizer A / B one month after sowing. Figure 2 (B) Growth of lettuce sprayed with foliar fertilizer C one month after sowing;

[0037] Figure 3This is a comparative diagram showing the lettuce planting effects under different treatment group conditions in the embodiment of the present invention;

[0038] Figure 4 This is a comparison chart showing the effects of water-soluble fertilizers prepared under different dilution conditions on the average plant height growth of wheatgrass cultured in shallow trays;

[0039] Figure 5 This is a comparative diagram showing the effects of water-soluble fertilizers prepared under different dilution conditions on the germination rate of wheat grass cultured in shallow trays;

[0040] Figure 6 This is a comparative diagram showing the effects of water-soluble fertilizers prepared under different pH conditions on the average plant height growth of wheatgrass cultured in shallow trays;

[0041] Figure 7 This is a comparison of the water-soluble fertilizer with a pH of 6.5 and the wheat grass hydroponic growth under water conditions in the shallow tray in the embodiment of the present invention; wherein, Figure 7 (A) is a photo of wheatgrass growing in a shallow hydroponic culture under the condition of water-soluble fertilizer with a pH of 6.5. Figure 7 (B) is a photo showing the actual growth of wheatgrass in a shallow tray under water conditions;

[0042] Figure 8 Comparison of the effects of water-soluble fertilizers prepared with different pH regulators on the growth of hydroponically grown wheatgrass. DETAILED DESCRIPTION

[0043] The following is a detailed description of the technical solution of the present invention, which does not limit the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention.

[0044] The "high COD wastewater" used in the embodiments of the present invention refers to the high COD wastewater generated during the stacking of Maotai-flavor liquor lees, and its parameter indicators are shown in Table 1 below;

[0045] Table 1 High COD wastewater parameter indicators

[0046] parameter concentration <![CDATA[Chemical Oxygen Demand (COD cr )]]> 250000mg / L <![CDATA[Biochemical Oxygen Demand (BOD5)]]> 130000mg / L Suspended solids (SS) 3000mg / L pH 4.5 Total nitrogen (TN) 7500mg / L <![CDATA[Ammonia nitrogen (NH3-N)]]> 3500mg / L Total phosphorus (TP) 3500mg / L Cr 0.185mg / L Cd 0.014mg / L As 0.026mg / L Pb 0.150mg / L Hg <0.0028mg / L

[0047] According to the parameter indicators of high COD wastewater in Table 1, it can be seen that the toxic and harmful components of the high COD wastewater used in the present invention meet the relevant standards for the preparation of water-soluble fertilizers "Limit Requirements for Mercury, Arsenic, Cadmium, Lead and Chromium in Water-Soluble Fertilizers" (NY1110-2010).

[0048] The "calcium magnesium phosphate fertilizer" used in the embodiments of the present invention is sourced from Yunnan Agricultural Development Group Co., Ltd. It is produced using a blast furnace process, where selected raw materials such as phosphate rock, serpentine, silica, and dolomite are melted at 1400-1800°C in a blast furnace and then water-quenched to produce a mineral powder containing readily absorbed phosphorus, silicon, magnesium, calcium, and various other plant-beneficial nutrients. The organically certified "calcium magnesium phosphate fertilizer" contains 15.40% effective phosphorus pentoxide by mass.

[0049] Example 1 Study on the Effect of Water-soluble Fertilizers of Different pH Values ​​on Lettuce Seed Germination

[0050] 1) Preparation of water-soluble fertilizer

[0051] Take high COD wastewater and dilute it 100 times. Specifically, take 10mL of high COD wastewater and add it to 990mL of water. After dilution, the COD cr , BOD5, SS, pH, TN, NH3-N, TP, Cr, Cd, As, Pb, and Hg were 2500mg / L, 1300mg / L, 30mg / L, 4.7, 75mg / L, 35mg / L, 35mg / L, 1.85μg / L, 0.14μg / L, 0.26μg / L, 1.50μg / L, and <0.028μg / L, respectively. ;

[0052] Calcium magnesium phosphate fertilizer is added to the diluted wastewater to adjust the pH, and the pH of the diluted wastewater is adjusted to 4.7, 5.0, 5.5, 6.0, 6.5, and 7.0 respectively; the wastewater after pH adjustment is filtered through six layers of gauze, and the filtrate is the water-soluble fertilizer with a pH of 4.7, 5.0, 5.5, 6.0, 6.5, and 7.0 respectively.

[0053] 2) Study on the effect of the prepared water-soluble fertilizer on lettuce seed germination

[0054] Experimental Method: Place a layer of circular filter paper on the bottom of a 9 cm diameter Petri dish and evenly place 10 lettuce seeds. Set up seven treatment groups, with three replicates for each treatment. Add the water-soluble fertilizer prepared in step 1) at pH values ​​of 4.7, 5.0, 5.5, 6.0, 6.5, and 7.0, respectively. A control group containing water was added. Maintain the water-soluble fertilizer at a depth of approximately 2 mm within the dish. Incubate at room temperature and observe the germination of the lettuce seeds. The treatment groups are as follows:

[0055] Water-soluble fertilizer added in treatment group 1: The high-COD wastewater was diluted 100 times and the pH was adjusted to 4.7;

[0056] Water-soluble fertilizer added in treatment group 2: high-COD wastewater was diluted 100 times and then the pH was adjusted to 5.0;

[0057] Water-soluble fertilizer added in treatment group 3: high-COD wastewater was diluted 100 times and then the pH was adjusted to 5.5;

[0058] Water-soluble fertilizer added in treatment group 4: high-COD wastewater was diluted 100 times and then the pH was adjusted to 6.0;

[0059] Water-soluble fertilizer added in treatment group 5: high-COD wastewater was diluted 100 times and then the pH was adjusted to 6.5;

[0060] Water-soluble fertilizer added in treatment group 6: high-COD wastewater was diluted 100 times and then the pH was adjusted to 7.0;

[0061] Control group: water.

[0062] Table 2 Germination of lettuce seeds after 3 days of cultivation

[0063]

[0064]

[0065] After 3 days of cultivation, the germination of lettuce is shown in Table 2. Compared with the germination rate of 73% in treatment group 7 (blank control group), treatment groups 1, 2, 3, 4, and 6 all had a certain inhibitory effect on the germination of lettuce seeds, and treatment groups 1, 2, 3, and 4 all showed mold. The water-soluble fertilizer with a pH of 6.5 prepared by the method of treatment group 5 did not show mold and significantly improved the germination rate of lettuce seeds.

[0066] Based on the above 3-day culture results, the above-mentioned treatment groups 4, 5, 6, and the control group were cultured for another 3 days and the growth of the lettuce seedlings was observed. The results are shown in Table 3.

[0067] Table 3 Growth of lettuce seedlings after 6 days of cultivation

[0068] Group Average bud length thick Treatment group 4 2.2cm 1.0mm Treatment group 5 3.2cm 1.0mm Treatment group 6 2.0cm 1.0mm Treatment group 7 (control group) 2.4cm 0.8mm

[0069] After 6 days of cultivation, the growth of the lettuce seedlings is shown in Table 3. The results in Table 3 show that compared with Treatment 7 (the control group), the water-soluble fertilizer added to Treatment Groups 4 and 6 had a certain inhibitory effect on the growth of the lettuce. After 6 days of cultivation, the average sprout length of the lettuce seedlings in Treatment Groups 4 and 6 was shorter than that in the blank control group. However, Treatment Group 5 had a significant effect on promoting the growth of the lettuce seedlings.

[0070] The comparison of the germination rates of lettuce seedlings cultured for three days and the growth of lettuce seedlings cultured for six days in each treatment group shows that diluting the high-COD wastewater generated during the storage of distiller's grains and adjusting its pH can produce a water-soluble fertilizer that can be directly utilized as a resource for lettuce seed germination and growth. Furthermore, the above results show that the water-soluble fertilizer prepared by diluting the high-COD wastewater 100 times and adjusting its pH to 6.5 has a good effect on promoting the germination and growth of lettuce seeds when used for germination, without causing mold.

[0071] Example 2

[0072] The water-soluble fertilizer prepared by the method of Example 1 was used to study the effect of hydroponically growing lettuce. Based on the comparison results in Example 1, this example selected the water-soluble fertilizer with a pH of 6.5 to study the effect of hydroponically growing lettuce, and water was used as the control group. The details are as follows:

[0073] Ten lettuce seedlings with good growth (2 leaves) were selected and transferred to 250 mL triangular flasks for planting and culture. Treatment group 1: the triangular flask was filled with the water-soluble fertilizer with a pH of 6.5 prepared in Example 1; treatment group 2 (blank control): the triangular flask was filled with water; the lettuce was hydroponically cultured at room temperature and the hydroponic conditions of the lettuce were observed.

[0074] The hydroponic conditions of lettuce are as follows: After 3 days of cultivation, in group 1, which was filled with water-soluble fertilizer with a pH of 6.5, microorganisms multiplied rapidly, resulting in hypoxia, anaerobic bacteria multiplication, and the generation of a foul odor in the culture medium; after 7 days of cultivation, lettuce seedlings died; while in the control group, no obvious deaths occurred.

[0075] It can be seen from this that when the water-soluble fertilizer prepared by this method is used to cultivate plants that require deep water cultivation, the frequency of replacing the water-soluble fertilizer needs to be increased, but it will cause waste of resources, further increase the cost of wastewater treatment, and fail to achieve effective utilization of resources and save treatment costs.

[0076] Example 3 Effects of different dilution ratios of water-soluble fertilizers on lettuce planting

[0077] Base fertilizer, foliar fertilizer A, foliar fertilizer B, and foliar fertilizer C were prepared from high COD wastewater, as follows:

[0078] Base fertilizer: Dilute high COD wastewater 10 times and adjust the pH to 6.0, then filter through six layers of gauze;

[0079] Foliar fertilizer A: high COD wastewater was diluted 10 times and the pH was adjusted to 6.0, and filtered through six layers of gauze;

[0080] Foliar fertilizer B: high COD wastewater was diluted 50 times and the pH was adjusted to 6.0, and filtered through six layers of gauze;

[0081] Foliar fertilizer C: high COD wastewater was diluted 100 times and then the pH was adjusted to 6.0 and filtered through six layers of gauze;

[0082] The specific sowing and planting steps are as follows: the lettuce variety is glass lettuce; the diameter of the planting pot is 9 cm, the soil is fully crushed and mixed evenly, and then placed in the planting pot and flattened. The soil thickness is 8 cm, and 100 mL of base fertilizer (control is water) is irrigated. The operation is consistent for each treatment; after sowing, cover with a 0.3 cm soil layer, water regularly, and spray foliar fertilizer regularly. Spray the entire plant, including new leaves and the back of the leaves. After the lettuce grows to 5 leaves, retain one lettuce seedling with the best growth in each treatment.

[0083] Treatment 1: Irrigate with base fertilizer after sowing and spray foliar fertilizer A one month later, and spray again every half a month after one month;

[0084] Treatment 2: Irrigate with base fertilizer after sowing and spray foliar fertilizer B one month later, and spray again every half a month after one month;

[0085] Treatment 3: Apply base fertilizer after sowing and spray foliar fertilizer C one month later, and then spray again every half a month after one month;

[0086] Control: Irrigate with water after sowing and spray with water one month later, and then spray again every half a month after one month;

[0087] Each treatment was repeated in two groups and watering was done normally.

[0088] like Figure 1 As shown in the figure, one month after sowing, the lettuce treated with irrigated base fertilizer grew better than the blank control. Therefore, using water-soluble fertilizer prepared from high-COD wastewater as base fertilizer can significantly promote the growth of lettuce.

[0089] like Figure 2 As shown in FIG1 , one month after sowing, 22 days after the first foliar fertilizer spraying (7 days after the second foliar fertilizer spraying), yellow spots appeared on the lettuce leaves sprayed with foliar fertilizers A and B, while the lettuce leaves sprayed with foliar fertilizer C did not have the above phenomenon and the lettuce grew better. Figure 3 As shown, at harvest (2.5 months after sowing), the growth of lettuce in Treatments 1 and 2 was essentially identical to the control group, while treatment 3 exhibited the best growth, with no yellowing or disease on the leaves. The average biomass of the lettuce increased by approximately 35% compared to the control. Therefore, a water-soluble fertilizer with a pH of 6.0, obtained by diluting high-COD wastewater 100-fold, can also be used in lettuce cultivation, with significant yield increases.

[0090] Example 4 Study on the effect of water-soluble fertilizers prepared at different dilution ratios on wheatgrass shallow tray hydroponics

[0091] 1) Preparation of water-soluble fertilizer

[0092] After diluting high COD wastewater by 10, 20, 30, 50, 70, 100, 200, 300, 400, 500, 600, 700, and 800 times, calcium magnesium phosphate fertilizer was added to adjust the pH to 6.5 to obtain water-soluble fertilizers with different dilution ratios;

[0093] 2) Study on the effect of wheatgrass shallow tray hydroponics using the prepared water-soluble fertilizer

[0094] Method: Take the bottom of a culture dish with a diameter of 9 cm, lay a layer of round filter paper inside, and evenly place 20 wheatgrass seeds. Add the prepared water-soluble fertilizer with different dilution multiples into the culture dish (the initial addition amount is 15 mL), use water as the blank control, and conduct three parallel experiments for each treatment. During the culture process, add the corresponding water-soluble fertilizer every day, control the depth of the water-soluble fertilizer in the dish at about 2 mm, and culture at room temperature for one month. Measure the final plant height and germination rate of wheatgrass in each treatment.

[0095] The results are as follows Figure 4 、 Figure 5 As shown, when the dilution ratio is too low, such as when the dilution ratio is 10-30 times, it will inhibit the germination rate of wheatgrass seeds and the growth of wheat sprouts; when the water-soluble fertilizer prepared with a dilution ratio of greater than or equal to 50 times is used for wheatgrass shallow tray culture, it will not cause root necrosis and can promote the growth of wheatgrass, and can meet the nutrients required for wheatgrass growth. Compared with CK, when the dilution ratio is 50 times, the average plant height is 27.3% higher and the germination rate is 8.4% higher; the water-soluble fertilizer prepared with a dilution ratio of 70-200 times has a better effect, and the height of wheatgrass is 44.5% higher than the control. As the concentration of the water-soluble fertilizer increases, the color of the wheatgrass gradually deepens, and the wheatgrass leaves cultured with the water-soluble fertilizer diluted 100 times are dark green; while in the control group, the leaves of the wheatgrass are yellow.

[0096] Example 5 Study on the effect of water-soluble fertilizers prepared under different pH conditions on wheatgrass shallow tray hydroponics

[0097] 1) Preparation of water-soluble fertilizer

[0098] After diluting the high COD wastewater 100 times, the pH was adjusted to 4.5, 5.0, 5.5, 6.0, 6.5, and 7.0 respectively with calcium magnesium phosphate fertilizer, and then filtered to obtain water-soluble fertilizers with different pH values.

[0099] 2) Effects of water-soluble fertilizers with different pH values ​​on wheatgrass hydroponics

[0100] Methods: 20 wheatgrass seeds were evenly distributed on the bottom of a 9-cm-diameter Petri dish, lined with a circular layer of filter paper. The prepared water-soluble fertilizers of varying pH values ​​were added to the dish (15 mL initially). Water was used as a blank control. Three replicates were run for each treatment. The corresponding water-soluble fertilizers were added daily throughout the growth process, maintaining a depth of approximately 2 mm within the dish. The seeds were incubated at room temperature for one month. The final plant height of each treatment group was measured.

[0101] The results are as follows Figure 6 、 Figure 7 The results showed that the water-soluble fertilizer prepared by diluting high-COD wastewater 100 times and adjusting the pH to 6.5 with calcium magnesium phosphate fertilizer had the best effect on wheatgrass hydroponics, but the differences between the treatments were not significant. This shows that water-soluble fertilizer prepared from high-COD wastewater can be used for shallow tray hydroponics of wheatgrass.

[0102] Example 6 Effect of water-soluble fertilizers prepared with different pH regulators on the effect of wheatgrass shallow tray hydroponics

[0103] 1) Preparation of water-soluble fertilizer

[0104] Take high COD wastewater, dilute it 100 times, and adjust the pH to 6.5 with calcium magnesium phosphate fertilizer, sodium bicarbonate, and sodium bicarbonate + calcium carbonate (first adjust the pH to 6.0 with calcium carbonate and then adjust with sodium bicarbonate), respectively. After filtering, water-soluble fertilizer is prepared;

[0105] 2) Effect of water-soluble fertilizers prepared with different pH regulators on wheatgrass shallow tray hydroponics

[0106] Methods: 20 wheatgrass seeds were evenly distributed on the bottom of a 9-cm-diameter Petri dish, lined with a circular layer of filter paper. The prepared water-soluble fertilizer was added to each dish (15 mL initially), with water serving as a blank control. Three replicates were run for each treatment. The corresponding water-soluble fertilizer was added daily during growth, maintaining a depth of approximately 2 mm within the dish. The wheat plants were incubated at room temperature for three weeks. The final plant height of each treatment was measured.

[0107] The results are as follows Figure 8 As shown, according to Figure 8 The results showed that water-soluble fertilizer prepared with calcium magnesium phosphate as pH regulator had the best growth-promoting effect on wheatgrass.

[0108] Comparative Example 7 Effect of pH Adjustment Order on Preparation of Water-soluble Fertilizer

[0109] Calcium magnesium phosphate was used to adjust the pH value of the high-COD wastewater before and after diluting it 100 times. When the pH value of the high-COD wastewater was adjusted with calcium magnesium phosphate before diluting it 100 times, it was found that due to the high COD concentration, the solution was relatively thick. Without dilution, the solubility of calcium magnesium phosphate was low. More calcium magnesium phosphate was added to adjust the pH to 6.5, and more calcium magnesium phosphate was precipitated. After diluting it 100 times, the pH value of the water-soluble fertilizer had risen to about 8 due to the further dissolution of the precipitated calcium magnesium phosphate. Therefore, in the process of preparing water-soluble fertilizer using the method of the present invention, adjusting the pH before diluting the high-COD wastewater cannot effectively control the final pH value of the solution.

[0110] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A method for resource utilization of high COD wastewater, characterized in that: The steps include: 1) Dilution treatment of high COD wastewater; 2) adjusting the pH of the diluted wastewater; 3) filtering the wastewater after the pH adjustment to obtain a water-soluble fertilizer; 4) using the water-soluble fertilizer for seed germination and / or shallow tray hydroponics of crops and / or planting of crops; The dilution step in step 1) and the pH adjustment step in step 2) are not interchangeable; The high COD wastewater is the wastewater generated during the stacking of Maotai-flavor liquor lees; In step 1), the dilution treatment of the high COD wastewater includes: taking the high COD wastewater and adding it into water, and mixing it evenly; the dilution ratio is 50-200 times; In step 2), adjusting the pH of the diluted wastewater comprises: adding a pH regulator to the diluted wastewater to adjust the pH to 6.1-6.9; the pH regulator is selected from calcium magnesium phosphate.

2. The method according to claim 1, wherein In step 1), the dilution ratio is 70-200 times.

3. The method according to claim 1, wherein In step 1), the dilution ratio is 80-190 times.

4. The method according to claim 1, wherein In step 1), the dilution ratio is 80-150 times.

5. The method according to claim 1, wherein In step 1), the dilution ratio is 90-120 times.

6. The method according to claim 1, wherein In step 3), the filtering comprises: filtering through six layers of gauze.

7. The method according to claim 1, wherein When used for germination of lettuce seeds and / or shallow tray hydroponics of lettuce, in step 1), the dilution multiple is 80-150.

8. The method according to claim 1, wherein When used for germination of lettuce seeds and / or shallow tray hydroponics of lettuce, in step 2), the pH is adjusted to 6.1-6.

9.

9. The method according to claim 1, wherein When used for growing lettuce, in step 1), the dilution multiple is 80-150.

10. The method according to claim 1, wherein When used for growing lettuce, in step 2), the pH is adjusted to 6.0-6.

6.

11. The method according to claim 1, wherein When used for wheatgrass seed germination and / or shallow tray hydroculture of wheatgrass, in step 1), the dilution multiple is 70-200 times.

12. The method according to claim 1, wherein When used for wheatgrass seed germination and / or shallow tray hydroponics of wheatgrass, in step 2), adjust the pH to 6.3-6.

7.

13. A water-soluble fertilizer prepared according to any one of claims 1 to 12.

14. Use of the method according to any one of claims 1 to 12 or the water-soluble fertilizer according to claim 13 in the fields of crop seed germination cultivation and / or crop shallow tray hydroponics and / or crop planting.

15. The use according to claim 14, characterized in that The seed germination cultivation of the crops includes: seed germination cultivation of lettuce; the shallow tray hydroponics of the crops includes: shallow tray water cultivation of lettuce and shallow tray hydroponics of wheatgrass; and the planting of the crops includes planting of lettuce.

16. A method for germinating and cultivating crop seeds / or cultivating crops in shallow trays and / or planting crops, characterized in that: include: During the process of crop seed germination cultivation / or crop shallow tray hydroponics / or crop planting, the water-soluble fertilizer according to claim 13 is added.

17. The method according to claim 16, characterized in that The crops include lettuce and wheat grass.

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