Vegetable cultivation device and method through domestic sewage tail water cultivation

Abstract

The invention discloses a vegetable cultivation device and method using domestic sewage tail water for cultivation, the method comprises the following steps: selecting a vegetable variety to be cultivated, carrying out sowing pretreatment on vegetable seeds, and sowing after the pretreatment is finished; covering a mulching film on the seedling culture substrate, and growing in an artificial climate greenhouse to preserve heat and moisture; after the vegetable seeds germinate and cotyledons turn green, the soil is kept moist, and fertilization is conducted in good time; seedling exercising is carried out before field planting; transplanting the seedlings into a vegetable cultivation device, regularly monitoring growth parameters of vegetables, and regularly and quantitatively applying fertilizer; according to the edible characteristics and values of different vegetable varieties, harvesting is conducted in good time, and after harvesting is finished, transplanting of vegetable seedlings in proper seasons is conducted at the same time, so that annual hydroponic vegetable cultivation of domestic sewage tail water is achieved. The invention provides a set of complete vegetable cultivation device and method through domestic sewage tail water cultivation, four-season crop rotation can be achieved, rural sewage resources can be effectively utilized, the ecological environment is improved, and economic benefits are created for farmers.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater and sewage purification, and specifically relates to a vegetable cultivation device and method for cultivating vegetables through domestic sewage tail water. Background Art

[0002] In the context of increasingly tight global water resources, how to efficiently use and treat water resources has become a pressing issue. The management of rural domestic sewage is particularly important because it not only involves the reuse of water resources, but also affects the protection of the rural ecological environment and the quality of life of farmers. In recent years, the research on the use of rural domestic sewage tailwater for hydroponic vegetables has gradually attracted attention. The construction of a related technical system can not only effectively treat sewage, but also improve the rural economy and promote sustainable development.

[0003] Rural domestic sewage mainly comes from daily household activities, such as washing, kitchen waste treatment and human excrement. Due to the lack of effective sewage treatment facilities in many rural areas, a large amount of sewage is directly discharged, causing water pollution, accumulation of heavy metals in the soil and deterioration of the rural ecological environment. Therefore, how to scientifically and rationally treat these sewage and convert it into reusable resources is an urgent problem to be solved.

[0004] After proper treatment, sewage tail water can be used to grow hydroponic vegetables. Hydroponics is a new type of soilless cultivation technology that can improve plant growth efficiency and reduce dependence on soil by growing plants in nutrient solution. Using treated sewage tail water for hydroponics has the following advantages:

[0005] Resource recycling: by reprocessing sewage, domestic sewage is converted into production materials, effectively reducing the waste of water resources;

[0006] Improve water quality: The roots of vegetables grown in the hydroponic system can effectively absorb nutrients in the water, purify the water quality, and reduce the concentration of pollutants in the water;

[0007] Economic benefits: Hydroponic vegetables grow fast and have high yields, which can provide farmers with higher economic returns while promoting local economic development.

[0008] At present, the method of growing vegetables with domestic sewage tailwater is still in its infancy, and there is no unified and effective existing technology. In particular, although domestic sewage tailwater contains nitrogen, phosphorus and potassium required for plant growth, the content is very low, and it is difficult for vegetables to grow luxuriantly with domestic sewage tailwater. If fertilizers are directly added to the water body, it will further pollute the water body, which is not worth the loss. Therefore, how to build a technology for hydroponically growing vegetables with rural domestic sewage tailwater needs to be developed. Summary of the invention

[0009] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide a vegetable cultivation device and method for cultivating vegetables through domestic sewage tail water.

[0010] In order to achieve the above purpose and the above technical effect, the technical solution adopted by the present invention is:

[0011] The invention discloses a vegetable cultivation device for cultivating through domestic sewage tail water, comprising a floating island frame, a sponge, a water-absorbing fiber strip and a buoyancy adjustment box, wherein the floating island frame is floated in the domestic sewage tail water body, a plurality of floating island grooves penetrating up and down are arranged on the floating island frame, the sponge is attached to the lower surface of the floating island frame, a plurality of root fixing grooves penetrating up and down are arranged on the sponge, the floating island grooves and the root fixing grooves are aligned up and down, the diameter of the root fixing grooves is smaller than the diameter of the floating island grooves, a plurality of water-absorbing fiber strips are provided and fixed on the lower surface of the sponge, the roots of the seedlings after training are placed in the root fixing grooves, and the stems of the seedlings pass through the floating island grooves, a plurality of buoyancy adjustment boxes are arranged on the floating island frame, the buoyancy adjustment boxes are placed in the domestic sewage tail water body, the interior of the buoyancy adjustment boxes is hollow, and the height at which the device floats on the water surface is adjustable by adjusting the weight of the buoyancy adjustment boxes.

[0012] Furthermore, there are four buoyancy regulating boxes, and one buoyancy regulating box is respectively arranged at the four corners of the floating island frame.

[0013] The present invention also discloses a vegetable cultivation method using domestic sewage tail water, comprising the following steps:

[0014] S1. Select the vegetable varieties to be cultivated and process the vegetable seeds before sowing;

[0015] S2, sowing after pre-treatment;

[0016] S3. After sowing, cover the seedling medium with a ground film and grow it in an artificial climate greenhouse to keep warm and moist;

[0017] S4. After the vegetable seeds germinate and the cotyledons turn green, keep the soil moist and apply fertilizer in time;

[0018] S5. Harden the seedlings 5-7 days before planting;

[0019] S6. Transplant the seedlings into the vegetable cultivation device, place the vegetable cultivation device in the tailwater of domestic sewage, regularly monitor the growth parameters of the vegetables, apply fertilizers regularly and quantitatively, and regularly check the stability of the device to ensure that it floats stably in the water;

[0020] S7. Harvest vegetables at the right time according to their edible characteristics and value, and measure their yield, quality and food safety indicators. After harvesting, transplant vegetable seedlings of the appropriate season to achieve year-round hydroponic vegetable cultivation in domestic sewage tail water.

[0021] Furthermore, in step S1, the vegetable varieties include one or a combination of lettuce, spinach, Chinese cabbage, Chinese kale, bee clam greens, meat vegetable, Chinese cabbage, and black moss.

[0022] Furthermore, in step S1, the step of treating the vegetable seeds before sowing includes:

[0023] 1) Drying seeds

[0024] Select the vegetable varieties you want to cultivate, and before sowing the vegetable seeds, choose a sunny day to dry the seeds for 2-3 hours;

[0025] 2) Germination

[0026] First soak the seeds in trisodium phosphate for 10-30 minutes, remove and wash, then soak the seeds in 40-60℃ warm water for 4-5 hours; spread the soaked seeds evenly in the seedling tray, cover with absorbent cotton cloth, germinate at 25-30℃, and sow when 70% of the seeds turn white.

[0027] Furthermore, in step S2, the step of sowing includes:

[0028] Use plug tray seedling cultivation, choose peat as the seedling medium, water it thoroughly in advance, set holes on the peat seedling medium, plant 2-3 seeds in each hole, and then cover it with 1.0-1.5cm thick seedling medium.

[0029] Furthermore, in step S3, the temperature of the seeds is controlled at 30-35° C. before germination, at 24-26° C. after germination, and at 70-90% humidity.

[0030] Furthermore, in step S4, the temperature during the vigorous growth period of the seedlings cannot be too high. The temperature is controlled but not the water to prevent the seedlings from growing too tall. The daytime temperature is controlled at 25-28°C and the nighttime temperature is controlled at 15-20°C. If the seedlings are deficient in nitrogen and phosphorus during the vigorous growth period, nitrogen and phosphorus fertilizers are sprayed on the leaves in the evening.

[0031] Furthermore, in step S5, the step of performing seedling hardening 5-7 days before planting includes:

[0032] Lower the temperature of the seedbed: the daytime temperature should be controlled at 18-20℃ and the nighttime temperature should be controlled at 6-15℃;

[0033] Control water: Do not water during the seedling hardening period to make the soil in the bed "white";

[0034] Peeling off the film: First peel off part of the film, and as the seedling hardening time increases, finally peel off the film completely to allow the seedlings to adapt to the open field environment. When the seedlings reach the planting standards, they can be transplanted.

[0035] Further, in step S6, the vegetable cultivation device includes a floating island frame, a sponge, a water-absorbing fiber strip and a buoyancy adjustment box, the floating island frame is floated in the domestic sewage tail water body, a plurality of floating island slots penetrating from top to bottom are arranged on the floating island frame, the sponge is attached to the lower surface of the floating island frame, a plurality of root fixing slots penetrating from top to bottom are arranged on the sponge, the floating island slot and the root fixing slot are aligned up and down, the diameter of the root fixing slot is smaller than the diameter of the floating island slot, there are a plurality of water-absorbing fiber strips and they are fixed on the lower surface of the sponge, the roots of the seedlings after training are placed in the root fixing slots, the stems of the seedlings pass through the floating island slots, a plurality of buoyancy adjustment boxes are arranged on the floating island frame, the buoyancy adjustment boxes are placed in the domestic sewage tail water body, and the interior of the buoyancy adjustment boxes is hollow;

[0036] When the roots of the seedlings after exercise are placed in the root fixing groove for less than 7 days, the weight of the buoyancy adjustment box is increased to immerse the sponge under the water surface; when the roots of the seedlings after exercise are placed in the root fixing groove for more than or equal to 7 days, the weight of the buoyancy adjustment box is reduced to make the sponge on the water surface and the water-absorbing fiber strips are located under the water surface. The water-absorbing fiber strips absorb water through capillary action to keep the sponge moist, and the coated fertilizer is added to the upper surface of the sponge through the floating island groove.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1) The present invention provides a complete vegetable cultivation method using domestic sewage tailwater, including the steps of pre-sowing treatment of vegetable seeds, sowing, seedling management, seedling hardening before planting, planting, growth management and vegetable harvesting, which can not only effectively utilize rural sewage resources and improve the ecological environment, but also create economic benefits for farmers;

[0039] 2) The present invention provides a variety of cold-resistant vegetable varieties, which can be rotated with conventional varieties in four seasons, which can not only ensure the purification effect of tail water in winter, but also increase the annual output of hydroponic vegetables and increase economic income;

[0040] 3) The present invention provides a vegetable cultivation device, which can realize two use states of the sponge body being located below the water surface and above the water surface. The use state is switched by adjusting the weight of the buoyancy regulating box. When the seedlings are just planted in the device and the roots have not yet penetrated into the sponge body, in order to ensure that the roots of the seedlings can effectively absorb water, the sponge body is located below the water surface, and the roots of the seedlings are also located below the water surface. After the seedlings grow for a period of time, the root system becomes longer and the lateral roots penetrate into the sponge body. At this time, the weight of the buoyancy regulating box is reduced to make the device float. The sponge body is located on the water surface, and the water-absorbing fiber strips are located below the water surface. Since the roots of the seedlings are relatively long, part of them are also in the water. The water-absorbing fiber strips absorb water through capillary action to keep the sponge body moist. The coated fertilizer is put onto the upper surface of the sponge body through the floating island trough. The coated fertilizer is slowly decomposed to form a nutrient zone in the sponge body. The seedlings can absorb the fertilizer through the lateral roots. The advantage of this arrangement is that the fertilizer will not enter the tail water of domestic sewage, thereby not further increasing water pollution. At the same time, the fertilizer can also be absorbed by vegetables to ensure the normal growth of vegetables. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0042] Figure 2 A top view of the present invention;

[0043] Figure 3 It is a structural schematic diagram of the floating island frame of the present invention;

[0044] Figure 4 It is a schematic structural diagram of the sponge of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0046] Obviously, the drawings described below are only some examples or embodiments of the present invention. For those of ordinary skill in the art, the present invention can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for those of ordinary skill in the art related to the contents disclosed in the present invention, some changes in design, manufacturing or production based on the technical contents disclosed in the present invention are just conventional technical means, and should not be understood as the contents disclosed in the present invention are insufficient.

[0047] like Figure 1-4 As shown, the present invention discloses a vegetable cultivation device for cultivating through domestic sewage tail water, comprising a floating island frame 1, a sponge 2, a water-absorbing fiber strip 3 and a buoyancy regulating box 4, wherein the floating island frame 1 is floated in the domestic sewage tail water body, a plurality of floating island slots 11 penetrating from top to bottom are arranged on the floating island frame 1, the sponge 2 is attached to the lower surface of the floating island frame 1, a plurality of root fixing slots 21 penetrating from top to bottom are arranged on the sponge 2, the floating island slots 11 and the root fixing slots 21 are aligned up and down, the diameter of the root fixing slots 21 is smaller than the diameter of the floating island slots 11, there are a plurality of water-absorbing fiber strips 3 and they are fixed on the lower surface of the sponge 2, the roots of the seedlings after training are placed in the root fixing slots 21, the stems of the seedlings pass through the floating island slots 11, a plurality of buoyancy regulating boxes 4 are arranged on the floating island frame 1, the buoyancy regulating boxes 4 are placed in the domestic sewage tail water body, the buoyancy regulating boxes 4 are hollow inside, and the height at which the device floats on the water surface is adjustable by adjusting the weight of the buoyancy regulating boxes 4.

[0048] In some embodiments, there are four buoyancy regulating boxes 4 , and one buoyancy regulating box 4 is respectively disposed at the four corners of the floating island frame 1 .

[0049] The present invention also discloses a vegetable cultivation method using domestic sewage tail water, comprising the following steps:

[0050] S1. Select the vegetable varieties to be cultivated and process the vegetable seeds before sowing. The steps include:

[0051] 1) Drying seeds

[0052] Select the vegetable varieties you want to cultivate and dry the seeds before sowing. Specifically, choose a sunny day, spread the seeds on newspapers or cotton cloth, and dry them for 2-3 hours to increase the germination rate and germination potential of the seeds.

[0053] 2) Germination

[0054] Soak the seeds in trisodium phosphate for 10-30 minutes, remove and wash, then soak in 40-60℃ warm water for 4-5 hours; spread the soaked seeds evenly in the seedling tray, cover with absorbent cotton cloth, germinate at 25-30℃, and sow when 70% of the seeds are white;

[0055] S2, after the pre-treatment, sowing is carried out, the steps include:

[0056] Use 50-hole trays with a specification of 54cm×28cm for seedling cultivation, choose peat as the seedling medium, water it thoroughly in advance, set holes on the seedling medium peat, plant 2-3 seeds in each hole, and then cover it with 1.0-1.5cm thick peat medium;

[0057] S3. Pre-emergence management

[0058] After sowing, cover the seedling medium with mulch and grow in an artificial climate greenhouse to keep warm and moisturize. Temperature control: The temperature before seed germination is controlled at 30-35℃, the temperature after germination is controlled at 24-26℃, and the humidity is controlled at 70-90%;

[0059] S4. Management during the seedling stage

[0060] After the vegetable seeds germinate and the cotyledons turn green, keep the soil moist. The temperature during the vigorous growth period of the seedlings should not be too high. Controlling the temperature instead of the water can prevent the seedlings from growing too tall. Temperature control: The daytime temperature is controlled at 25-28℃, the nighttime temperature is controlled at 15-20℃, and the minimum temperature is above 10℃. If the vegetable seedlings are deficient in nitrogen and / or phosphorus during the vigorous growth period, you can spray 0.2% potassium dihydrogen phosphate and / or 0.2% urea on the leaves, and the foliar spraying should be done in the evening;

[0061] S5. Hardening of seedlings before planting

[0062] Before transplanting, in order to improve the adaptability of seedlings to the environment after transplanting and shorten the seedling acclimatization time after transplanting, the seedlings should be hardened 5-7 days before transplanting. The specific measures are:

[0063] Lower the temperature of the seedbed: the daytime temperature should be controlled at 18-20℃, the nighttime temperature should be controlled at 13-15℃, and the cold-resistant varieties can be controlled at 6-8℃;

[0064] Control water: Generally, no watering is done during the seedling hardening period to make the soil in the bed "white";

[0065] Film removal: First remove part of the film, and as the hardening time increases, finally remove all the film to allow the seedlings to adapt to the open field environment. When the seedlings reach the planting standard, they will be planted;

[0066] S6. Vegetable planting and growth management

[0067] Transplanting the seedlings Figure 1-4In the vegetable cultivation device shown, the vegetable cultivation device is placed in the tail water of domestic sewage, and the growth parameters of the vegetables, including plant height, leaf area, stem thickness, etc., are regularly monitored. Slow-release fertilizer is added regularly and quantitatively, and the stability of the device is regularly checked to ensure that it floats stably in the water. Specifically, when the roots of the exercised seedlings are placed in the root fixing groove 21 for less than 7 days, stones and the like are put into the buoyancy adjustment box 4 to increase the weight of the buoyancy adjustment box 4 so that the sponge 2 is immersed under the water surface. When the roots of the exercised seedlings are placed in the root fixing groove 21 for more than or equal to 7 days, stones and the like are taken out to reduce the weight of the buoyancy adjustment box 4 so that the device floats, the sponge 2 is located on the water surface, and the water-absorbing fiber strips 3 are located under the water surface. The water-absorbing fiber strips 3 absorb water through capillary action to keep the sponge 2 moist, and the coating fertilizer is put on the upper surface of the sponge 2 through the floating island groove 11. Coated fertilizers can be Osmocote, EnviroGro, etc. The external coating of these fertilizers can control the water entering the fertilizer particles, thereby slowly releasing nutrients, suitable for a variety of plants and vegetables;

[0068] S7. Harvest vegetables in a timely manner according to their edible characteristics and value, and measure their yield, quality and food safety indicators. After harvesting, transplant vegetable seedlings of the appropriate season to achieve year-round hydroponic vegetable cultivation in domestic sewage tailwater.

[0069] In some embodiments, the vegetable varieties include one or a combination of lettuce, spinach, tall white cabbage, thousand-headed Chinese cabbage, bee clam vegetable, meat vegetable, Chinese cabbage, black hemp leaf moss, etc., and the cold-resistant vegetable varieties include one or a combination of one or more of dragon bud king cabbage, horse ear cabbage, green leafed cabbage, etc.

[0070] Example 1

[0071] like Figure 1-4 As shown, a vegetable cultivation device for cultivating vegetables by domestic sewage tailwater includes a floating island frame 1, a sponge 2, a water-absorbing fiber strip 3 and a buoyancy adjustment box 4, wherein the floating island frame 1 is floated in the domestic sewage tailwater body, a plurality of floating island grooves 11 penetrating vertically are arranged on the floating island frame 1, a sponge 2 is attached to the lower surface of the floating island frame 1, a plurality of root fixing grooves 21 penetrating vertically are arranged on the sponge 2, the floating island grooves 11 and the root fixing grooves 21 are aligned vertically, and the root fixing grooves 21 are aligned vertically. The diameter is smaller than that of the floating island trough 11, there are several water-absorbing fiber strips 3 and they are fixed on the lower surface of the sponge body 2, the roots of the exercised seedlings are placed in the root fixing groove 21, and the stems of the seedlings pass through the floating island trough 11, and a buoyancy adjustment box 4 is respectively arranged at the four corners of the floating island frame 1. There are four buoyancy adjustment boxes 4 in total, and the buoyancy adjustment boxes 4 are placed in the tail water body of domestic sewage. The inside of the buoyancy adjustment box 4 is hollow, and the height at which the device floats on the water surface can be adjusted by adjusting the weight of the buoyancy adjustment box 4.

[0072] A vegetable cultivation method using domestic sewage tail water, comprising the following steps:

[0073] S1. Select the vegetable varieties to be cultivated and process the vegetable seeds before sowing. The steps include:

[0074] 1) Drying seeds

[0075] Select the lettuce to be cultivated and dry the seeds before sowing. Specifically, choose a sunny day, spread the seeds on newspaper or cotton cloth, and dry them for 2 hours to improve the germination rate and germination potential of the seeds.

[0076] 2) Germination

[0077] Soak the seeds in 10% trisodium phosphate for 20 minutes, remove and wash, and then soak them in 55℃ warm water for 4 hours. Spread the soaked seeds evenly in the seedling tray, cover with absorbent cotton cloth, and germinate at 25℃. When 70% of the seeds are white, they can be sown;

[0078] S2, after the pre-treatment, sowing is carried out, the steps include:

[0079] Use 50-hole trays with a specification of 54cm×28cm, choose peat as the seedling medium, water it thoroughly in advance, set holes on the seedling medium peat, plant 2 seeds in each hole, and then cover it with 1.0cm thick peat medium;

[0080] S3. After sowing, cover the seedling medium with mulch and grow it in an artificial climate greenhouse to keep warm and moisturize. Temperature control: The temperature before seed germination is controlled at 30℃, the temperature after germination is controlled at 24℃, and the humidity is controlled at 70%;

[0081] S4. After the vegetable seeds germinate and the cotyledons turn green, keep the soil moist. The temperature during the vigorous growth period of the seedlings should not be too high. Controlling the temperature instead of the water can prevent the seedlings from growing too tall. Temperature control: The daytime temperature is controlled at 25°C and the nighttime temperature is controlled at 15°C. If the vegetable seedlings are deficient in nitrogen and / or phosphorus during the vigorous growth period, you can spray 0.2% potassium dihydrogen phosphate and / or 0.2% urea on the leaves, and the foliar spraying should be done in the evening;

[0082] S5. Before transplanting, in order to improve the adaptability of seedlings to the environment after transplanting and shorten the time for seedlings to grow after transplanting, the seedlings should be hardened 5 days before transplanting. The specific measures are:

[0083] Lower the temperature of the seedbed: the daytime temperature should be controlled at 18℃, the nighttime temperature should be controlled at 13℃, and the cold-resistant varieties can be controlled at 6℃;

[0084] Control water: Generally, no watering is done during the seedling hardening period to make the soil in the bed "white";

[0085] Film removal: First remove part of the film, and as the hardening time increases, finally remove all the film to allow the seedlings to adapt to the open field environment. When the seedlings reach the planting standard, they will be planted;

[0086] S6. Transplant the seedlings Figure 1-4 In the vegetable cultivation device shown, the vegetable cultivation device is placed in the tail water of domestic sewage, and the growth parameters of the vegetables, including plant height, leaf area, stem thickness, etc., are regularly monitored. Slow-release fertilizer is added regularly and quantitatively, and the stability of the device is regularly checked to ensure that it floats stably in the water. Specifically, when the roots of the exercised seedlings are placed in the root fixing groove 21 for less than 7 days, stones and the like are put into the buoyancy adjustment box 4 to increase the weight of the buoyancy adjustment box 4 so that the sponge 2 is immersed under the water surface. When the roots of the exercised seedlings are placed in the root fixing groove 21 for more than or equal to 7 days, stones and the like are taken out to reduce the weight of the buoyancy adjustment box 4 so that the device floats, the sponge 2 is located on the water surface, and the water-absorbing fiber strips 3 are located under the water surface. The water-absorbing fiber strips 3 absorb water through capillary action to keep the sponge 2 moist, and the coating fertilizer is put on the upper surface of the sponge 2 through the floating island groove 11. Coated fertilizers can be Osmocote, these fertilizers have an external coating that controls the entry of water into the fertilizer particles, thereby slowly releasing nutrients, suitable for a variety of plants and vegetables;

[0087] S7. Harvest vegetables in a timely manner according to their edible characteristics and value, and measure their yield, quality and food safety indicators. After harvesting, transplant vegetable seedlings of the appropriate season to achieve year-round hydroponic vegetable cultivation in domestic sewage tailwater.

[0088] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0089] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A vegetable cultivation device for cultivating vegetables using domestic sewage tailwater, characterized in that: The invention comprises a floating island frame, a sponge, a water-absorbing fiber strip and a buoyancy regulating box. The floating island frame is floated in a domestic sewage tailwater body. The floating island frame is provided with a plurality of floating island grooves which are passed through from top to bottom. The sponge is attached to the lower surface of the floating island frame. The sponge is provided with a plurality of root fixing grooves which are passed through from top to bottom. The floating island grooves and the root fixing grooves are aligned up and down. The diameter of the root fixing grooves is smaller than the diameter of the floating island grooves. There are a plurality of water-absorbing fiber strips which are fixed on the lower surface of the sponge. The roots of the seedlings after exercise are placed in the root fixing grooves. The stems of the seedlings pass through the floating island grooves. A plurality of buoyancy regulating boxes are provided on the floating island frame. The buoyancy regulating boxes are placed in the domestic sewage tailwater body. The interior of the buoyancy regulating boxes is hollow. By adjusting the weight of the buoyancy regulating boxes, the height at which the device floats on the water surface can be adjusted.

2. The vegetable cultivation device for cultivating vegetables by using domestic sewage tail water according to claim 1, characterized in that: There are four buoyancy regulating boxes in total, and one buoyancy regulating box is respectively arranged at the four corners of the floating island frame.

3. A vegetable cultivation method using domestic sewage tailwater, characterized in that: The following steps are involved: S1. Select the vegetable varieties to be cultivated and process the vegetable seeds before sowing; S2, sowing after pre-treatment; S3. After sowing, cover the seedling medium with a ground film and grow it in an artificial climate greenhouse to keep warm and moist; S4. After the vegetable seeds germinate and the cotyledons turn green, keep the soil moist and apply fertilizer in time; S5. Harden the seedlings 5-7 days before planting; S6. Transplant the seedlings into the vegetable cultivation device, place the vegetable cultivation device in the tailwater of domestic sewage, regularly monitor the growth parameters of the vegetables, apply fertilizers regularly and quantitatively, and regularly check the stability of the device to ensure that it floats stably in the water; S7. Harvest vegetables at the right time according to their edible characteristics and value, and measure their yield, quality and food safety indicators. After harvesting, transplant vegetable seedlings of the appropriate season to achieve year-round hydroponic vegetable cultivation in domestic sewage tail water.

4. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S1, the vegetable varieties include one or a combination of lettuce, spinach, Chinese cabbage, Chinese spinach, bee clam vegetable, meat vegetable, Chinese cabbage, and black moss.

5. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S1, the step of treating vegetable seeds before sowing includes: 1) Drying seeds Select the vegetable varieties you want to cultivate, and before sowing the vegetable seeds, choose a sunny day to dry the seeds for 2-3 hours; 2) Germination First soak the seeds in trisodium phosphate for 10-30 minutes, remove and wash, then soak the seeds in 40-60℃ warm water for 4-5 hours; spread the soaked seeds evenly in the seedling tray, cover with absorbent cotton cloth, germinate at 25-30℃, and sow when 70% of the seeds turn white.

6. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S2, the sowing step includes: Use plug tray seedling cultivation, choose peat as the seedling medium, water it thoroughly in advance, set holes on the peat seedling medium, plant 2-3 seeds in each hole, and then cover it with 1.0-1.5cm thick seedling medium.

7. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S3, the temperature of the seeds is controlled at 30-35° C. before germination, the temperature is controlled at 24-26° C. after germination, and the humidity is controlled at 70-90%.

8. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S4, the temperature during the vigorous growth period of the seedlings cannot be too high. The temperature is controlled but not the water to prevent the seedlings from growing too tall. The daytime temperature is controlled at 25-28°C and the nighttime temperature is controlled at 15-20°C. If the seedlings are deficient in nitrogen and phosphorus during the vigorous growth period, nitrogen and phosphorus fertilizers are sprayed on the leaves in the evening.

9. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S5, the step of hardening the rice seedlings 5-7 days before planting includes: Lower the temperature of the seedbed: the daytime temperature should be controlled at 18-20℃ and the nighttime temperature should be controlled at 6-15℃; Control water: Do not water during the seedling hardening period to make the soil in the bed "white"; Peeling off the film: First peel off part of the film, and as the seedling hardening time increases, finally peel off the film completely to allow the seedlings to adapt to the open field environment. When the seedlings reach the planting standards, they can be transplanted.

10. The vegetable cultivation method using domestic sewage tail water as claimed in claim 3, characterized in that: In step S6, the vegetable cultivation device includes a floating island frame, a sponge, a water-absorbing fiber strip and a buoyancy adjustment box. The floating island frame is floated in the domestic sewage tail water body. The floating island frame is provided with a plurality of floating island grooves that penetrate up and down. The sponge is attached to the lower surface of the floating island frame. The sponge is provided with a plurality of root fixing grooves that penetrate up and down. The floating island grooves and the root fixing grooves are aligned up and down. The diameter of the root fixing groove is smaller than the diameter of the floating island groove. There are a plurality of water-absorbing fiber strips that are fixed to the lower surface of the sponge. The roots of the seedlings after training are placed in the root fixing grooves. The stems of the seedlings pass through the floating island grooves. The floating island frame is provided with a plurality of buoyancy adjustment boxes. The buoyancy adjustment boxes are placed in the domestic sewage tail water body. The buoyancy adjustment boxes are hollow inside. When the roots of the seedlings after exercise are placed in the root fixing groove for less than 7 days, the weight of the buoyancy adjustment box is increased to immerse the sponge under the water surface; when the roots of the seedlings after exercise are placed in the root fixing groove for more than or equal to 7 days, the weight of the buoyancy adjustment box is reduced to make the sponge on the water surface and the water-absorbing fiber strips are located under the water surface. The water-absorbing fiber strips absorb water through capillary action to keep the sponge moist, and the coated fertilizer is added to the upper surface of the sponge through the floating island groove.

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