CN113443786A

CN113443786A - Biogas slurry treatment and resource utilization system and method

Info

Publication number: CN113443786A
Application number: CN202110764397.1A
Authority: CN
Inventors: 冷天华; 袁昌定; 何道领; 韦艺媛; 高敏
Original assignee: Chongqing Chunjiang Environmental Protection Technology Co ltd
Current assignee: Chongqing Chunjiang Environmental Protection Technology Co ltd
Priority date: 2021-07-06
Filing date: 2021-07-06
Publication date: 2021-09-28

Abstract

The invention discloses a system and a method for biogas slurry treatment and resource utilization. The biogas slurry treatment system comprises a buffer pool, an ozone advanced oxidation treatment device and an ecological pond. The buffer pool can play a role in buffering and temporarily storing; the ozone advanced oxidation treatment device can increase the concentration of dissolved oxygen in the biogas slurry while disinfecting and oxidizing the biogas slurry, thereby ensuring the normal growth of cress and fishes in the ecological pond; the ecological pond utilizes the biogas slurry oxidized by ozone to float and plant the cress, the cress can be harvested 4-5 times a year, the annual output is 1 ten thousand kg/mu, and the annual output value is 3 ten thousand yuan/mu; in addition, snakeheads and chubs are mixed and put into the ecological pond, the culture density is 500-1000 fishes/mu, and the annual output value is about 1000 yuan/mu. The biogas slurry treatment system is simple to operate, low in operation and management cost, free of season limitation in water cresses planting, continuous, stable and efficient in purification effect, and capable of achieving the water quality standard for farmland irrigation (GB5084-2005) after biogas slurry is treated by the system, so that recycling of biogas slurry is realized.

Description

Biogas slurry treatment and resource utilization system and method

Technical Field

The invention relates to the technical field of biogas slurry treatment, in particular to a system and a method for biogas slurry treatment and resource utilization.

Background

In recent years, livestock and poultry breeding in China is rapidly developed, and according to 'Chinese countryside statistics yearbook', the number of live pigs in China in 2019 is 69382.4 ten thousand, beef cattle in China is 4397.5 ten thousand, poultry in China is 1308936.0 ten thousand, and dairy cows in the end of the year are 1037.7 ten thousand, so that the problem of agricultural non-point source pollution caused by a large amount of livestock and poultry feces generated each year is increasingly prominent. The first pollution source census data in China shows that the annual production of excrement and urine of the breeding industry in China is 2.43 hundred million tons, and the annual production of urine is 1.63 hundred million tons, so that how to effectively treat the excrement and the dirt of livestock and poultry becomes a serious environmental problem. The biogas engineering can effectively treat the livestock and poultry manure, can also produce clean energy and fertilizer, and brings considerable economic benefit, but the biogas engineering mode of centralized treatment usually produces a large amount of biogas slurry. Researches show that the biogas slurry contains rich nitrogen, phosphorus, potassium, calcium, magnesium, trace elements, humic acid, amino acid, vitamins, auxin and other bioactive substances, and is mainly used for returning to farmland. However, the common mode of returning biogas slurry to the field cannot absorb the increasing amount of biogas slurry. The utilization and the consumption of the biogas slurry are realized through resource treatment, and the urgent need of realizing stable production and sustainable development of large-scale livestock and poultry breeding is gradually met.

The water cress is an edible umbelliferae herbaceous plant, and has the characteristics of no seasonal limitation, repeated harvesting, large fertilizer absorption amount, high economic value and the like besides active substances for reducing blood pressure, blood fat and cancer. Can bring higher economic value while continuously purifying the water quality. However, organic matters in the biogas slurry, nitrogen, phosphorus and other nutrient elements are too high in concentration, and the water cress can die when the water cress is directly used for cultivation of the water cress.

The ozone advanced oxidation technology is used for carrying out oxidation treatment on organic pollutants by generating a large amount of hydroxyl radicals. The ozone treatment can not only effectively remove the organic pollutants which are difficult to degrade, but also improve the biodegradability of the wastewater. The oxidation-reduction potential of the ozone is 2.07V, the strong oxidizability can obviously change the molecular structure of organic matters in the wastewater, and the secondary product of the ozone after oxidation reaction is oxygen, so that the secondary pollution is avoided, the dissolved oxygen concentration of the biogas slurry can be increased, and the subsequent system treatment is facilitated.

Disclosure of Invention

The purpose of the invention can be realized by the following technical scheme: comprises a buffer pool, an ozone advanced oxidation treatment device and an ecological pond which are connected in sequence according to a treatment process; the buffer pool is provided with a buffer pool water inlet and a buffer pool water outlet, the buffer pool water inlet is filled with water through a pipeline, the buffer pool water outlet adopts a water outlet valve to discharge water, and an iron net is arranged at the front end of the water outlet valve to intercept solid matters and prevent the pipeline from being blocked; the ozone advanced oxidation treatment device is provided with a high-energy ozone generator, the high-energy ozone generator is provided with a self-suction ejector, and the self-suction ejector is connected with an air supply pump through a pipeline; the ecological pond is provided with a liquid inlet end, a circulating water exchange end and a liquid outlet end, the liquid inlet end adopts a pipeline for water inflow, the circulating water exchange end adopts a circulating water pump for pumping biogas slurry to an ozone advanced oxidation treatment device for circulating treatment, the liquid outlet end adopts a pipeline for automatically flowing out water, and the effluent of the ecological pond is recycled and used for aquaculture and agricultural irrigation.

In the biogas slurry treatment and resource utilization system, the buffer pool, the ozone advanced oxidation treatment device, the ecological pond and the fish pond can be arranged in a line in sequence, and can also be arranged in multiple lines according to an operation site, and the process sequence of liquid flow is ensured to be correct by structures such as pipelines.

The buffer tank can temporarily store biogas slurry after anaerobic fermentation treatment, play a role in buffering and temporary storage, and can effectively control the running condition of the whole system.

The high-energy ozone generator is arranged in the ozone advanced oxidation treatment device, and can generate high-purity ozone, oxidize various organic substances in the biogas slurry, reduce COD concentration and realize biogas slurry disinfection and deodorization; and pure oxygen aeration can be carried out, so that the concentration of dissolved oxygen in the biogas slurry is increased, and the subsequent ecological pond system treatment is facilitated.

The water cresses in the ecological pond have the advantages of large fertilizer absorption amount, no season limitation and the like, can absorb and utilize rich nutrient elements in the biogas slurry, can provide good environmental conditions at the root of the water cresses, generate a large amount of planktons, can be used for normal growth of snakeheads and chubs, form a complete biological chain, and realize efficient utilization of organic matters, nitrogen and phosphorus elements in the biogas slurry.

In the biogas slurry treatment and resource utilization system, the hydraulic retention time of the buffer tank is 5-10 min, so that the operation, maintenance and management of the system are facilitated while the water quality and the water quantity are adjusted; the aperture of the iron net at the front end of the water outlet valve is 70-80 meshes, so that the pipeline can be effectively prevented from being blocked.

In the biogas slurry treatment and resource utilization system, the ozone advanced oxidation treatment device is provided with a high-energy ozone generator, the high-energy ozone generator performs aeration in a pipeline through a self-suction ejector, the self-suction ejector is connected with a flow meter and a high-concentration ozone generator through pipelines, the flow meter is connected with a molecular sieve through a pipeline, the molecular sieve is connected with an air drying agent through a pipeline, the air drying agent is connected with a precision filter through a pipeline, the precision filter is connected with a cold dryer through a pipeline, the cold dryer is connected with a condenser through a pipeline, and the condenser is connected with an oil-free air compressor through a pipeline; a multi-time drying system is arranged in the high-energy ozone generator, so that the removing effect on water vapor in air can be enhanced, and the problem of difficulty in ozone production in a high-humidity environment is solved; adopting a molecular sieve to remove carbon dioxide and nitrogen, ensuring that the ozone generation concentration reaches 99 percent and the energy consumption is as low as 4.2 kw.h/kgO 3; the self-suction ejector can ensure that gas and liquid are mixed more uniformly and can reduce the generation of foam.

In the biogas slurry treatment and resource utilization system, the number of matched live pigs per mu in the ecological pond is less than or equal to 75, cress are planted in the ecological pond by using the floating bed, the planting density is 200-250 plants/m 2, the area of the floating bed of cress accounts for 50% of the water surface area of the ecological pond, and various nutrient substances in biogas slurry can be utilized to the maximum extent while the normal growth and development of cress are ensured; the water in the ecological pond can be lifted to an ozone advanced oxidation treatment device for ozone aeration treatment by the circulating water exchange, so that the dissolved oxygen content in the water can be increased while organic matters are degraded, disinfection and sterilization are carried out, and the normal growth of water celery in the ecological pond is ensured; the snakehead and the chub feed on plankton, and form a stable ecological system with cress and the like, so that the nitrogen and phosphorus content of the biogas slurry is effectively reduced.

The biogas slurry treatment and recycling system implemented by the invention at least has the following beneficial effects:

1) the ozone can effectively remove organic matters, not only can oxidize organic nitrogen into ammonia nitrogen to facilitate the absorption and utilization of the cress, but also can increase the concentration of dissolved oxygen in the biogas slurry and enhance the biodegradability of the system; meanwhile, the ozone has the effects of sterilization, disinfection, decoloration and deodorization, and can obviously reduce the total suspended solids of the biogas slurry.

2) The water cresses not only contain active substances for reducing blood pressure, blood fat and cancer, but also have the advantages of no seasonal restriction, large fertilizer absorption amount and the like, thereby ensuring the continuity of water purification; meanwhile, the cresses can be repeatedly harvested for 4-5 times in one year, the average annual output is 4000 kg/mu, the average annual output value is 2-3 ten thousand yuan/mu, and the cresses have high economic value.

3) And the mixed culture density of the snakeheads and the chubs is 500-1000 fish/mu, and planktons in the ecological pond are eaten for a long time, so that the utilization rate of various nutrient elements in the biogas slurry is improved, and the purification effect on the biogas slurry is strengthened.

4) After ozone oxidation, water cress absorption and fish purification, the COD effluent concentration of the biogas slurry is 100-200 mg/L, the NH4+ -N effluent concentration is 20-50 mg/L, and the TP effluent concentration is 5-8 mg/L, the treated biogas slurry is recycled and used for aquaculture, agricultural irrigation and the like, and biogas slurry treatment and resource utilization are effectively realized.

The operation method for biogas slurry treatment and resource utilization comprises the following steps:

1) enabling the biogas slurry generated after solid-liquid separation and anaerobic fermentation treatment to enter a buffer tank through a pipeline, and opening a water outlet valve of the buffer tank after the biogas slurry stays in the buffer tank for 5-10 min;

2) the biogas slurry passing through the buffer tank sequentially enters an ozone advanced oxidation treatment device, a high-energy ozone generator is started, the principle of a Venturi scrubber is utilized, a self-suction ejector is adopted to inject gas generated by the high-energy ozone generator into a biogas slurry conveying pipeline, and the gas and the liquid realize mixed aeration in the pipeline;

3) the biogas slurry after ozone oxidation treatment sequentially enters the ecological pond, a circulating water pump in the ecological pond is timely started to exchange water in a circulating mode, cress float on the water surface through a floating bed, carbon dioxide is absorbed and fixed under photosynthesis, nutritive salts such as nitrogen and phosphorus in the biogas slurry are utilized to grow, plankton in water is used as food for snakeheads and chubs, a complete biological chain is formed, the content of nitrogen and phosphorus in the biogas slurry is effectively reduced, and the biogas slurry after the ecological pond is treated is recycled and used for aquaculture and agricultural irrigation.

In the operation method, the COD concentration of the biogas slurry entering the buffer tank is 8000-12000 mg/L, NH4+ -N, and the concentration of the biogas slurry entering the buffer tank is 500-600 mg/L, TP, and the concentration of the biogas slurry is 80-100 mg/L in the step 1).

In the operation method, the aeration is divided into ozone aeration and pure oxygen aeration in the step 2), the ozone aeration and the pure oxygen aeration are carried out in a pipeline, the pipeline adopts a PE (polyethylene) pipe or a PPR (polypropylene random) pipe with DN 50-110, in order to ensure that gas stays in the pipeline for more than 1min, the pipeline is arranged in a U shape along the periphery of the ecological pond, the U-shaped pipe is provided with a pipeline liquid inlet, and the length of the pipeline between the pipeline liquid inlet and an aeration port is not less than 100 m; if the length of the pipeline is less than 100m, adopting 5-10 m long PE pipes or PPR pipes of DN 110-150 near the aeration port, and adopting DN 50-110 pipes to form a U shape along the periphery of the ecological pond along the residual length; the high-energy ozone generator adopts an air source to produce ozone, the concentration of the produced ozone is more than 99%, the ozone aeration is divided into two stages, the first stage is a biogas slurry water inlet stage, aeration is carried out for 20min when water enters the water inlet stage, the second stage is a circulating water changing stage, and aeration is carried out for 20min in the circulating water changing stage; pure oxygen aeration is carried out at 1:00-2:00 in the morning, once a day, 20min in summer and 10min in winter.

In the operation method, the ecological pond is characterized in that in the step 3), the depth of water is controlled to be 0.6-1.5 m, the hydraulic power stays for 15-20 d in summer and 35-40 d in winter, the water is circularly changed by a circulating water pump at 12:00-13:00 noon every day, the flow of the circulating water pump is 25m3/h, the water circulates for 1-2 h in summer and the water circulates for 1-4 h in winter; the water cress are harvested once 45-60 days after seedling throwing, are harvested for 30-40 days in the hottest and coldest months, and are harvested 4-5 times each year.

In the operation method, the COD concentration of the biogas slurry treated by the system is 100-200 mg/L, the NH4+ -N concentration is 20-50 mg/L, and the TP concentration is 5-8 mg/L, so that the working method reaches the Water quality Standard for Farmland irrigation (GB 5084-2005). .

Drawings

The drawings of the invention are illustrated as follows:

fig. 1 is a process flow diagram of a biogas slurry treatment and resource utilization system in example 1.

FIG. 2 is a flow chart of the operation of the high-energy ozone generator in example 3.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

Example 1

Referring to fig. 1, fig. 1 is a process flow diagram of a system for biogas slurry treatment and resource utilization, which comprises a buffer pool, an ozone advanced oxidation treatment device and an ecological pond which are sequentially connected according to a treatment process; the buffer pool is provided with a buffer pool water inlet and a buffer pool water outlet, the buffer pool water inlet is filled with water through a pipeline, the buffer pool water outlet adopts a water outlet valve to discharge water, and an iron net is arranged at the front end of the water outlet valve to intercept solid matters and prevent the pipeline from being blocked; the ozone advanced oxidation treatment device is provided with a high-energy ozone generator, the high-energy ozone generator is provided with a self-suction ejector, and the self-suction ejector is connected with an air supply pump through a pipeline; the ecological pond is provided with a liquid inlet end, a circulating water exchange end and a liquid outlet end, the liquid inlet end adopts a pipeline for water inflow, the circulating water exchange end adopts a circulating water pump for pumping biogas slurry to an ozone advanced oxidation treatment device for circulating treatment, the liquid outlet end adopts a pipeline for automatically flowing out water, and the effluent of the ecological pond is recycled and used for aquaculture and agricultural irrigation.

In the biogas slurry treatment and resource utilization system, the buffer pool, the ozone advanced oxidation treatment device, the ecological pond and the fish pond can be arranged in a line in sequence, and can also be arranged in multiple lines according to an operation field, and the process sequence of liquid flow is ensured to be correct through structures such as pipelines.

The buffer tank can temporarily store biogas slurry treated after anaerobic fermentation, play a role in buffering and temporary storage, and can effectively control the running condition of the whole system.

Example 2

After ozone is dissolved in water, a large amount of hydroxyl free radicals are generated, and the hydroxyl free radicals have strong oxidizability, degrade organic matters in the biogas slurry and realize disinfection, sterilization, decoloration and deodorization; in addition, the ozone can also convert organic nitrogen into ammonia nitrogen, so that the subsequent cress can be absorbed and utilized; the cress has the advantages of large fertilizer absorption amount, no season limitation and the like, can absorb and utilize rich nutrient elements in the biogas slurry, can provide good environmental conditions at the root of the cress, generates a large amount of plankton, can be used for normal growth of snakeheads and chubs, forms a complete biological chain, and realizes efficient utilization of organic matters, nitrogen and phosphorus elements in the biogas slurry; the invention has been practically applied in Hechuan district of Chongqing city and Yue chi county of Sichuan province, wherein a farm in Hechuan district of Chongqing city is used for pig and cattle mixed cultivation, 5000 pigs and 700 cattle are cultivated, the daily output of biogas slurry is about 100m3, the farm is provided with 10 mu ecological ponds, and the average daily treatment capacity is 15m 3; the method comprises the following steps of (1) breeding live pigs in a farm in Yuchi county of Sichuan province, wherein the pigs are slaughtered 13000 years, the daily yield of biogas slurry is about 100m3, the farm is provided with 40 mu of ecological ponds, and the average daily treatment capacity is 50m 3; detecting and analyzing effluent of the two-place system to obtain results in tables 1 and 2; table 1 shows the heavy metal effluent concentration in the testing base of the Hechuan district in Chongqing city, and as can be seen from table 1, no heavy metal is detected in the biogas slurry treated by the method, so that the biogas slurry meets the requirements of the relevant standards of farmland irrigation; table 2 shows the effluent water quality conditions of the biogas slurry in the experimental base of Yuchi county in Sichuan province, and the treated biogas slurry is neutral, and the indexes related to COD, NH4+ -N, TP and fecal coliform bacteria group all reach the Water quality Standard for Farmland irrigation (GB5084-2005) as can be seen from Table 2; the biogas slurry treated in the two experimental places is used for agricultural irrigation, so that the biogas slurry is absorbed and treated, and the resource utilization is realized.

Table 1 heavy metal effluent concentration units in the test base of the united chuan area in Chongqing city: mg/L

Table 2 unit of biogas slurry effluent water quality condition in experimental base in Yue pool county of Sichuan province: mg/L, pH dimensionless, faecal coliform: MPN/100ML

Example 3

Please refer to fig. 2, fig. 2 is a flow chart of the high-energy ozone generator, the high-energy ozone generator absorbs air through an oil-free air compressor, the oil-free air compressor is connected with a condenser through a pipeline, the condenser is connected with a cooling dryer through a pipeline, the cooling dryer is connected with a precision filter through a pipeline, the precision filter is connected with an air drying agent through a pipeline, the air drying agent is connected with an electromagnetic valve through a pipeline, the electromagnetic valve is connected with a molecular sieve through a pipeline, the molecular sieve is connected with a pressure stabilizing tank through a pipeline, the pressure stabilizing tank is connected with the air filter through a pipeline, the air filter is connected with a flow meter through a pipeline, the flow meter is connected with a pure oxygen self-priming ejector and a high-concentration ozone generator through a pipeline, and the high-concentration ozone generator is connected with a self-priming ejector through a pipeline.

In the above embodiment, the energy consumption of the high-energy ozone generator is as low as 4.2kw · h/kgO3, the condenser condenses the sucked air for the first time, the freeze dryer condenses the air for the second time, the precision filter filters the condensed air, the air drying agent dries the air, and the vapor in the air is removed by condensation and drying, so that the high-energy ozone generator can be applied to high-humidity areas; the molecular sieve can remove nitrogen, carbon dioxide and the like in air to obtain high-purity oxygen, the pressure stabilizing tank can collect pure oxygen and stabilize air pressure, the air filter can filter gas impurities again, the flowmeter can measure gas flow and is convenient to control aeration quantity, the ozone generator can convert the pure oxygen into ozone, the ozone concentration reaches more than 99%, and the self-suction ejector can enable gas and liquid to be mixed more uniformly and can reduce foam.

Example 4

The invention adopts the water cress to purify the biogas slurry, and the water cress not only contains active substances for reducing blood pressure, blood fat, cancer and the like, but also has the advantages of no seasonal limitation, repeated harvesting, large fertilizer absorbing amount, high economic value and the like; the cress has two planting modes, the first mode is that particle seeds which are grown at the end of summer are collected and sowed in a flat muddy field after being soaked in biogas slurry for several days for seedling raising, and after 20 days, seedling transplanting and separate planting are carried out, wherein the needed seeds are 1 kg/mu; the second method is that old stems with the growing period exceeding 60d are cut into sections (about 10 cm) or old roots with whiskers are uniformly spread and cultivated, the required segmented stems or root whiskers are 2000-2666 kg/mu, and special germination accelerating procedures are not needed in the two methods; when the cress are mature, collecting samples of the cress, and then sending the cress to a third-party detection mechanism for detection, wherein the detection result of the content of pollutants in the cress is shown in table 3, and the detection result of the nutrition condition of the cress is shown in table 4; the results in Table 3 show that no pesticide residue is detected in the water cress, and although the fluorine element is 0.43mg/kg, the fluorine element does not exceed the national food limit standard; detecting heavy metals in the water cresses, and finding that all the heavy metals are lower than the limit value of the national standard; the results in table 4 show that the content of vitamin C in 100g of cress is as high as 33.5mg, the detected nutrient substances also comprise protein, various essential amino acids for human bodies, crude fiber, soluble sugar and the like, and the cress cultured in a floating mode by biogas slurry has high nutritional value while meeting food safety conditions.

Table 3 pesticide and heavy metal residue status in cress: unit: mg/kg

Table 4 nutrient content in cress:

detecting items	Unit of	Measured value
			Protein	g/100g	2.55
Amino acid (Total amount)	g/100g	1.08
			Aspartic acid	g/100g	0.147
Threonine	g/100g	0.0561
			Serine	g/100g	0.0498
Glutamic acid	g/100g	0.146
			Glycine	g/100g	0.0620
Alanine	g/100g	0.0690
			Valine	g/100g	0.0688
Methionine	g/100g	0.0124
			Isoleucine	g/100g	0.0544
Leucine	g/100g	0.101
			Tyrosine	g/100g	0.0441
Phenylalanine	g/100g	0.0642
			Histidine	g/100g	0.0393
Lysine	g/100g	0.0631
			Arginine	g/100g	0.0556
Proline	g/100g	0.0462
			Coarse fiber	％	0.9
Soluble sugar	％	0.57
			Vitamin C	mg/100g	33.5

The implementation effect is as follows:

the system and the method for biogas slurry treatment and resource utilization are applied and popularized in multiple areas of Sichuan and Chongqing, and the water quality index of biogas slurry effluent in all the areas reaches the Water quality Standard for Farmland irrigation (GB 5084-2005).

Compared with the traditional method, the biogas slurry resource utilization method described in the patent has obvious advantages, high-concentration organic matters in the biogas slurry can be utilized, nutrient elements such as nitrogen and phosphorus are used for culturing cress, the cress can be harvested 4-5 times a year, the annual output is 1 ten thousand kg/mu, the annual output value is 3 ten thousand yuan/mu, the snakeheads and the chubs in the pond are reused for purifying water, a complete ecological system is formed, the annual output values of the snakeheads and the chubs are about 1000 yuan/mu, and finally the treated biogas slurry is recycled and used for aquaculture, agricultural irrigation and the like, so that environment protection and efficient recycling of resources are achieved, and sustainable development of production and ecology is guaranteed.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.

Claims

1. A system for biogas slurry treatment and resource utilization is characterized by comprising a buffer pool, an ozone advanced oxidation treatment device and an ecological pond which are sequentially connected according to a treatment process; the buffer pool is provided with a buffer pool water inlet and a buffer pool water outlet, the buffer pool water inlet is filled with water through a pipeline, the buffer pool water outlet adopts a water outlet valve to discharge water, and an iron net is arranged at the front end of the water outlet valve to intercept solid matters and prevent the pipeline from being blocked; the ozone advanced oxidation treatment device is provided with a high-energy ozone generator, the high-energy ozone generator is provided with a self-suction ejector, and the self-suction ejector is connected with an air supply pump through a pipeline; the ecological pond is provided with a liquid inlet end, a circulating water exchange end and a liquid outlet end, the liquid inlet end adopts a pipeline for water inflow, the circulating water exchange end adopts a circulating water pump for pumping biogas slurry to an ozone advanced oxidation treatment device for circulating treatment, the liquid outlet end adopts a pipeline for automatically flowing out water, and the effluent of the ecological pond is recycled and used for aquaculture and agricultural irrigation.

2. The system for biogas slurry treatment and resource utilization according to claim 1, wherein the hydraulic retention time of the buffer tank is 5-10 min, so that the system can be conveniently operated, maintained and managed while the water quality and the water quantity are adjusted; the aperture of the iron net at the front end of the water outlet valve is 70-80 meshes.

3. The biogas slurry treatment and resource utilization system according to claim 1, wherein the ozone advanced oxidation treatment device is provided with a high-energy ozone generator, the high-energy ozone generator adopts a self-suction ejector to aerate in a pipeline, the self-suction ejector is connected with a flow meter and a high-concentration ozone generator through a pipeline, the flow meter is connected with a molecular sieve through a pipeline, the molecular sieve is connected with an air drying agent through a pipeline, the air drying agent is connected with a precision filter through a pipeline, the precision filter is connected with a cold dryer through a pipeline, the cold dryer is connected with a condenser through a pipeline, and the condenser is connected with an oil-free air compressor through a pipeline.

4. The biogas slurry treatment and resource utilization system according to claim 1, wherein the number of matched live pigs per mu in the ecological pond is less than or equal to 75, cress are planted in the ecological pond by using a floating bed, the planting density is 200-250 plants/m 2, the area of the floating bed of cress accounts for 50% of the water surface area of the ecological pond, snakeheads and chubs are mixed and thrown in the ecological pond, and the mixed breeding density is 500-1000 tails/mu.

5. The operation method of the biogas slurry ecological treatment culture system of claim 1 is characterized by comprising the following steps:

1) enabling the biogas slurry generated after solid-liquid separation and anaerobic fermentation treatment to enter a buffer tank through a pipeline, and opening a valve at a water outlet of the buffer tank after the biogas slurry stays in the buffer tank for 5-10 min;

6. The operation method according to claim 5, wherein in the step 1), the concentration of Chemical Oxygen Demand (COD) of the biogas slurry entering the buffer tank is 8000-12000 mg/L, ammonia nitrogen (NH4+ -N) is 500-600 mg/L, and Total Phosphorus (TP) is 80-100 mg/L.

7. The operation method according to claim 5, wherein in the step 2), the aeration is divided into ozone aeration and pure oxygen aeration, both of which are carried out in a pipeline, the pipeline adopts a PE pipe or a PPR pipe with DN 50-110, in order to ensure that the gas stays in the pipeline for more than 1min, the pipeline is arranged in a U shape along the periphery of the ecological pond, the U-shaped pipe is provided with a pipeline liquid inlet, and the length of the pipeline between the pipeline liquid inlet and the aeration port is not less than 100 m; if the length of the pipeline is less than 100m, adopting 5-10 m long PE pipes or PPR pipes of DN 110-150 near the aeration port, and adopting DN 50-110 pipes to form a U shape along the periphery of the ecological pond along the residual length; the high-energy ozone generator adopts an air source to produce ozone, the concentration of the produced ozone is more than 99%, the ozone aeration is divided into two stages, the first stage is a biogas slurry water inlet stage, aeration is carried out for 20min when water enters the water inlet stage, the second stage is a circulating water changing stage, and aeration is carried out for 20min in the circulating water changing stage; pure oxygen aeration is carried out at 1:00-2:00 in the morning, once a day, 20min in summer and 10min in winter.

8. The operation method according to claim 5, wherein in the step 3), the ecological pond controls the water depth to be 0.6-1.5 m, the summer hydraulic power stays for 15-20 d, the winter hydraulic power stays for 35-40 d, the water is circularly changed by a circulating water pump at 12:00-13:00 at noon every day, the flow rate of the circulating water pump is 25m3/h, the summer circulates for 1-2 h, and the winter circulates for 1-4 h; the water cress are harvested once 45-60 days after seedling throwing, and are harvested for 30-40 days in the hottest and coldest months, and are harvested for 4-5 times each year.

9. The operation method according to claim 5, wherein the COD concentration of the biogas slurry treated by the system is 100-200 mg/L, the NH4+ -N concentration is 20-50 mg/L, and the TP concentration is 5-8 mg/L, which reaches the Water quality Standard for Farmland irrigation (GB 5084-2005).