CN104058558B - A kind of circulation utilization method of wastewater from pig farm - Google Patents

Abstract

The present invention discloses a kind of wastewater from pig farm circulation utilization method, comprises the following steps: after the excrement dirt produced in the production process of pig farm is homogeneous, carry out anaerobically fermenting; The natural pond liquid that anaerobically fermenting obtains carries out three grades of aerating oxidation at least 2 cover tertiary oxidation ponds be arranged in parallel; A biological degradation is carried out through the natural pond liquid that three grades of aerating oxidation obtain; Water after biological degradation waterplant in circulation water channel carries out secondary biological degradation; Through the biodegradable water accumulation of secondary, discharge after reaching emission standard.The present invention can solve the pressure that piggery waste brings, and reduces the use water pressure in water resources anxiety area, can reduce simultaneously and produce vegetables required purchase fertilizer expenses.Present invention achieves the regeneration of the energy, the combination of plant husbandry and aquaculture, achieve " zero release " of Animal Husbandry Pollution, finally can realize the Sustainable development of livestock industry.This wastewater from pig farm circulation utilization method simplicity of design, implements convenient, simple to operate and safe and practical, suitablely promotes.

Description

A method for recycling pig farm sewage

technical field

The invention belongs to the technical field of pig farm sewage treatment and utilization, in particular to a method for recycling pig farm sewage, and more specifically to the treatment of biogas slurry obtained by anaerobic fermentation of pig farm manure.

Background technique

With the vigorous development of large-scale and intensive pig farming, the discharge of sewage and sewage from pig farms has increased sharply, causing great pressure on environmental protection. Another major source of environmental pollution after livestock, and large-scale pig farms are also major polluters in livestock farms. The national environmental protection department has recognized this point. Most of the manure produced by large-scale pig farms adopts a simple biogas fermentation treatment mode. The liquid can be returned to the field nearby, which can not only solve the environmental pressure brought by the pig farm, but also realize the resource utilization of pig farm manure. However, with the continuous reduction of arable land in China, there is not enough land around many pig farms to decompose the manure generated by the pig farms. The above-mentioned manure treatment mode is not applicable to most pig farms. At the same time, the production water in the pig farms It is also a challenge for areas with scarce water resources. That is to say, although most pig farms now use biogas fermentation of manure to relieve a lot of environmental pressure to a certain extent, the biogas slurry produced after biogas fermentation has always been a problem that plagues pig farm investors. Manure has brought serious damage to the agricultural ecological environment and affected the sustainable development of the overall economy of the surrounding areas. Therefore, it is necessary to propose a scientific and reasonable pig farm sewage treatment model.

Contents of the invention

The object of the present invention is to provide a method for recycling pig farm sewage in order to solve the existing problems in the existing pig farm manure treatment technology.

The purpose of the present invention is achieved through the following technical solutions:

A method for recycling pig farm sewage, which sequentially performs anaerobic fermentation, three-stage aeration oxidation, primary biodegradation, and secondary biodegradation treatment, including the following steps:

(1) After the manure produced in the pig farm production process is homogenized, anaerobic fermentation is carried out;

(2), the biogas slurry obtained by anaerobic fermentation is subjected to three-stage aeration oxidation in at least two sets of three-stage oxidation ponds arranged in parallel;

(3) The biogas slurry obtained through the three-stage aeration oxidation undergoes a biodegradation through aquatic plants;

(4) The water after primary biodegradation is subjected to secondary biodegradation through the aquatic plants in the circulating water channel;

(5) The water after secondary biodegradation is accumulated and discharged after reaching the discharge standard.

In step (1), the manure generated during the pig farm production process is fully homogenized in the homogenization tank. Homogenization is a process of mixing pig manure and sewage. The homogenized manure is placed in the biogas anaerobic fermentation tower Perform anaerobic fermentation. Anaerobic fermentation of manure in a biogas anaerobic fermentation tower is a routine operation, and the removal rate of COD by anaerobic fermentation is generally between 80% and 90%.

In step (2), the biogas slurry is alternately aerated and oxidized in at least two sets of tertiary oxidation ponds arranged in parallel, and each set of tertiary oxidation ponds includes the first oxidation pond, the second oxidation pond and the third oxidation pond connected in sequence. Oxidation tank, the volumes of the first oxidation tank, the second oxidation tank and the third oxidation tank are 600m ³ , 400m ³ and 300m ³ respectively; the first oxidation tank, the second oxidation tank and the third oxidation tank are all equipped with There is an oxygen pump to make the oxygen in the air fully contact with the biogas slurry, increase the oxygen content of the biogas slurry, and ensure that the dissolved oxygen in the biogas slurry is 2.5-4.5mg/L. The purpose of setting the tertiary oxidation ponds in parallel is to make one set of tertiary oxidation ponds collect the biogas slurry, and the other set of tertiary oxidation ponds conduct static aeration and oxidation treatment of the biogas, so as to avoid oxidation caused by aeration while the biogas liquor flows in. A case where it doesn't work well.

Further preferably, the biogas slurry is alternately aerated and oxidized in 2 sets of tertiary oxidation ponds arranged in parallel (i.e. the tertiary oxidation ponds in the A area and the B area tertiary oxidation ponds arranged in parallel); the specific operation of the alternate aeration oxidation is: The biogas slurry first enters the first oxidation pond in area A at a flow rate of 5m ³ /h until it is full, and then begins to stand for aeration and oxidation; the biogas slurry in the first oxidation pond of area A is left for aeration and oxidation for 10-15 days, Then put the supernatant into the second oxidation tank in A area for secondary aeration and oxidation for 10-15 days, and 2/3 of the supernatant in the second oxidation tank in A area enters the third oxidation tank in A area for tertiary aeration Oxidation for 10-15 days; when the biogas slurry in the first oxidation pond of A area starts to stand for aeration and oxidation, the biogas slurry enters the first oxidation pond of B area at the same flow rate, and is treated according to the treatment method of the three-stage oxidation pond of A area The biogas slurry is aerated and oxidized step by step; the three-stage oxidation tanks in A and B areas are alternately aerated and oxidized, and the dissolved oxygen in the biogas slurry is maintained at 2.5-4.5mg/L during the aeration and oxidation process.

In step (3), the biogas slurry oxidized by the three-stage aeration stays in the aquatic plant field for 10-15 days to perform a biodegradation; the aquatic plant field is planted with aquatic plants. The planting density of the aquatic plants in the aquatic plant field is: 1m wide row, 0.8m narrow row, 0.6m spacing between plants, and 1400 pier per mu.

In step (4), the primary biodegraded water undergoes secondary biodegradation in the circulating water channel, and the flow rate of the water in the circulating water channel is 1-2 cm/s, which is conducive to the biodegradation of aquatic plants in the water channel. The circulating water channel is composed of multiple sections of horizontal channels, and each adjacent two sections of horizontal channels form a drop of 10-20 cm; each section of the horizontal channel is provided with at least one net cage, and aquatic plants are planted in the net cage. The circulating water canal is built around the periphery of the pig farm to form a biosafety isolation zone. According to the treatment situation, the water in the circulating canal can be pumped from the end of the canal to the starting point of the canal again, and biodegraded in multiple cycles.

The aquatic plants of the present invention are water hyacinth, lotus root, water bamboo, reed or calamus, preferably water bamboo. Aquatic plants are characterized by strong environmental adaptability, rapid growth, well-developed root system, and high water demand. They are suitable for planting in clay loam or soil with sufficient water sources, convenient irrigation, deep and soft soil, fertile soil, rich in organic matter, and strong water and fertilizer retention capabilities. in loam. Aquatic plants can consume most of the pollution indicators in sewage. The use of cages to plant aquatic plants in circulating water channels is convenient for controlling the salvage and collection of aquatic plants. As green feed for pig farms, it can also effectively control the spread of harmful plants that are defined by people.

In step (5), the secondary biodegraded water is accumulated in the sedimentation tank, and the supernatant is discharged into the discharge area.

The present invention also provides a recycling system for swine farm sewage, comprising a homogeneous pool, a biogas anaerobic fermentation tower, at least two sets of parallel tertiary oxidation pools, aquatic plant fields, and a circulating water channel. The homogeneous pool and The pig farm is connected, the homogeneous tank is connected to the biogas anaerobic fermentation tower through pipelines, and the biogas anaerobic fermentation tower is connected to the inlet of the tertiary oxidation tank. Each set of tertiary oxidation tanks includes the first oxidation tank and the second oxidation tank connected in sequence pond and the third oxidation pond; the third oxidation pond of each set of three-stage oxidation ponds leads to the aquatic plant field through pipelines, and the described aquatic plant field is connected with the circulating water channel through the water channel; the described circulating water channel is composed of multi-section horizontal The water channel is composed of two adjacent horizontal water channels forming a drop of 10-20cm, and at least one cage is arranged in each horizontal water channel; the circulating water channel is connected to the sedimentation tank; the sedimentation tank is connected to the discharge area.

Further preferably, the pig farm sewage recycling system is provided with two sets of tertiary oxidation ponds in parallel; each section of the horizontal water channel is provided with a net cage.

The water channel slate outside the aquatic plant field ridge is provided with holes for filtering the water once biodegraded by the aquatic plant field; the pipeline connecting the third oxidation pond of each set of three-level oxidation pools and the aquatic plant field With water pump.

The principles involved in the inventive method are as follows:

a. "Zero discharge principle": "Zero discharge" of sewage from pig farms is realized through the cycle of "pig breeding - sewage - anaerobic fermentation - aerobic oxidation - aquatic plants/aquatic plant biodegradation - pig breeding".

b. Low energy consumption: Choosing a constructed wetland with a small investment to treat pig farm sewage can significantly reduce the content of total phosphorus, total nitrogen, and heavy metals copper and zinc in manure.

c. The nutrients in the biogas slurry produced by the fermentation of pig farm manure can be used as organic fertilizer for aquatic plants for the growth of aquatic plants.

Compared with prior art, the beneficial effect of the present invention:

The pig farm sewage recycling method of the invention is simple, easy to implement, simple to operate, safe and practical, and suitable for popularization. On the one hand, it can ideally treat the sewage of pig farms, reduce the environmental pressure caused by pig farm manure, and reduce the water pressure in water-stressed areas; on the other hand, it can reduce the need to purchase organic fertilizers for the production of aquatic plants (vegetables) cost. Can greatly reduce the content of COD, N, P, Zn, Cu in the pig farm sewage through the treatment of the inventive method, the removal rate of COD in the pig farm sewage reaches 99.5%, the removal rate of total phosphorus (TP) reaches 99.5%, and the total nitrogen The removal rate of (TN) reached 76.1%, the removal rate of Cu reached 61.5%, and the removal rate of Zn reached 99.2%. Especially, the biodegradation of biogas slurry by aquatic plants can significantly remove COD, total phosphorus, total nitrogen, Heavy metal ions Cu and Zn. It has the characteristics of environmental protection, economy, energy saving and water saving. The method of the invention realizes the recycling of energy, the recycling of pig farm production water, the organic combination of planting and breeding, the realization of "zero discharge" of animal husbandry pollution, and finally the sustainable development of animal husbandry.

Description of drawings

Fig. 1 is the flow chart of the recycling method of pig farm sewage of the present invention;

Figure 2 is a schematic diagram of aeration and oxidation in a three-stage oxidation tank;

Fig. 3 is a schematic diagram of aquatic plant field filtration;

Figure 4 is a schematic diagram of biogas slurry degradation in circulating water channels.

In the figure, 1-pig farm, 2-homogeneous tank, 3-biogas anaerobic fermentation tower, 4-tertiary oxidation tank, 5-aquatic plant field, 6-circulating channel, 7-sedimentation tank, 8-discharge area, The first oxidation pool in area 9-A, the first oxidation pool in area 10-B, the second oxidation pool in area 11-A, the second oxidation pool in area 12-B, the third oxidation pool in area 13-A, the first oxidation pool in area 14-B Oxidation pond, 15-aquatic plant ridge, 16-reserve hole, 17-drainage stone slab, 18-cage.

detailed description

The present invention will be further described below in conjunction with specific cases.

Referring to Figures 1, 2, 3 and 4, a pig farm sewage recycling system includes a homogeneous tank (2), a biogas anaerobic fermentation tower (3), two sets of parallel tertiary oxidation tanks (4), an aquatic Plant fields (5), circulating water channels (6); each set of tertiary oxidation ponds includes first oxidation ponds (9, 10), second oxidation ponds (11, 12) and third oxidation ponds connected in sequence (13, 14); the homogeneous pond (2) is connected with the pig farm (1), the homogeneous pond (2) is connected with the biogas anaerobic fermentation tower (3) through the pipeline, and the biogas anaerobic fermentation tower (3) Connect with the first oxidation pond (9,10) inlet of every set of three-stage oxidation ponds, the third oxidation pond (13,14) of every set of three-stage oxidation ponds leads to aquatic plant field (5) through pipeline, connects the third The pipeline of the oxidation pond (13,14) and the aquatic plant field (5) is provided with a water pump; the water channel slab (17) outside the described aquatic plant field ridge (15) is provided with a retaining hole (16), and the aquatic plant field ( 5) Connect the circulating water channel (6) through the water channel; the circulating water channel (6) is composed of multiple sections of horizontal water channels, each adjacent two sections of horizontal water channels form a drop of 10-20cm, and a net is provided in each section of horizontal water channels. box (18); the circulation channel (6) is connected to the sedimentation tank (7); the sedimentation tank (7) is connected to the discharge area (8).

The volumes of the first oxidation pond (9,10), the second oxidation pond (11,12) and the third oxidation pond (13,14) are respectively 600m ³ , 400m ³ and 300m ³ ; the first oxidation pond ( 9, 10), the second oxidation pond (11, 12) and the third oxidation pond (13, 14) are equipped with oxygen pumps to allow the oxygen in the air to fully contact the biogas slurry and increase the oxygen content of the biogas slurry .

The width of the circulating water channel (6) is 3m, and the length of each horizontal channel is 4-6m; the specification of the net cage (18) is 2.5×3m ² or 2.5×4m ² .

A method for recycling pig farm sewage, comprising the following steps:

(1) After the manure produced in the production process of the pig farm (1) is fully homogenized in the homogenization tank (2), it is anaerobically fermented in the biogas anaerobic fermentation tower (3).

(2) The biogas slurry produced by anaerobic fermentation in the biogas anaerobic fermentation tower ( ³ ) enters two sets of three-stage oxidation ponds (4) connected in parallel for alternate aeration and oxidation. The flow rate of h enters the first oxidation pond (9) of A district until it is full, and begins to stand for aeration and oxidation. The biogas slurry in the first oxidation pond (9) of A district is left for aeration and oxidation for 10 days, and then the upper The supernatant enters the second oxidation pond (11) in the A district for secondary aeration oxidation for 10 days, and 2/3 of the supernatant in the second oxidation pond (11) in the A district enters the third oxidation pond (13) in the A district for Aerated and oxidized for 10 days; when the biogas slurry in the first oxidation pond of A area starts to stand still for aeration and oxidation, the biogas slurry enters the first oxidation pond of B area at the same flow rate of 5m ³ /h, and follows the three-stage oxidation method of A area The treatment method of the pond is to carry out step-by-step aeration and oxidation of the biogas slurry; the three-stage oxidation ponds in A and B areas are alternately aerated and oxidized, and the dissolved oxygen in the biogas slurry is maintained at 2.5-4.5mg/L during the aeration and oxidation process.

(3) The biogas slurry obtained by the three-stage aeration oxidation enters the aquatic plant field planted with Zizania (5) and stays for 15 days for a biodegradation. The planting density of Zizania in the aquatic plant field: 1m wide row, 0.8m narrow row, The plant spacing is 0.6m, and 1400 piers are planted per mu.

(4) The water obtained through a biodegradation treatment passes through the holes (16) on the slabs (17) of the outer canal (17) of aquatic plants and flows into the canal, and then enters the circulating canal (6) composed of multiple horizontal canals , the flow velocity of the water is controlled to be 1-2cm/s, and the water is simultaneously subjected to secondary biodegradation through Zizania in the net cage (18).

(5). The secondary biodegraded water is accumulated in the settling tank (7) for sedimentation, and the water reaching the discharge standard enters the discharge area (8) for discharge.

Applications

A pig farm with 1,200 basic sows in Jiangsu has a 2,000m ³ biogas anaerobic fermentation tower, and 20 acres of aquatic plant fields attached to it, where wild rice stems are planted. The pig farm sewage recycling method of the present invention is used to treat the pig farm sewage, and the contents of COD, total phosphorus, total nitrogen, and heavy metals Cu and Zn in each treatment stage are detected.

Table 1 Relevant environmental indicators at each stage of pig farm sewage recycling treatment (n=7)

Note: a, b, c, and d are compared in the same line, and the superscript without the same letter indicates a significant difference (P<0.05); A, B, C is compared in the same line, and the superscript without the same letter indicates an extremely significant difference (P<0.01); data Expressed as "mean ± standard error".

It can be seen from Table 1 that 86% of COD in manure can be removed by anaerobic fermentation treatment, and the COD value after fermentation is extremely significantly reduced (P<0.01); three-stage aeration oxidation removes 30% of COD in biogas slurry, The COD value in the water after the three-stage aeration oxidation was significantly lower than the COD value in the biogas slurry after anaerobic fermentation (P<0.05); 73% of the COD in the water after the three-stage oxidation was removed by one-time biodegradation, and one-time biodegradation was removed 83% of COD in the biodegraded water, and the total removal rate of COD in the final pig farm manure reaches 99.5%. After anaerobic fermentation, 7% of total phosphorus (TP) was removed, 3.8% of total phosphorus in biogas slurry was removed after three-stage oxidation, 56% of total phosphorus in water after three-stage oxidation was removed by primary biodegradation, and TP after primary biodegradation was removed by secondary biodegradation The total phosphorus in water is 98%, and the total removal rate of total phosphorus reaches 99.5%. The total removal rate of total nitrogen (TN) reached 76.1%, the total removal rate of Cu reached 61.5%, and the total removal rate of Zn reached 99.2%. In summary, adopting the method of the present invention to process pig farm manure can obviously remove COD, total phosphorus, total nitrogen, heavy metal ions Cu and Zn, and COD, TP, TN after treatment are far lower than <<Livestock and Poultry Breeding Industry Pollution> According to the Standard of Waste Discharge (GB18596-2001), the content of copper and zinc is also significantly reduced (P<0.01).

Table 2 Zn and Cu contents in soil of aquatic plant field and different parts of aquatic plants (n=5)

Note: A, B, C, and D are compared in the same row, and the superscript without the same letter means that the difference is extremely significant (P<0.01), and the data are expressed as "mean ± standard deviation".

It can be seen from Table 2 that the content of Cu and Zn in the soil of the aquatic plant field reaches the "Soil Environmental Quality Standard (Revised Edition)" GB15618-2008. my country has abolished the limit indicators of Fe, Cu and Zn in food because the intake of dietary Fe of Chinese residents is similar to that of developed countries, and the intake of Zn has a downward trend. The result in 2007 was lower than the level of developed countries, and the intake of Cu higher than in developed countries. At the same time, the intakes of Fe, Cu, and Zn were far below the tolerated maximum intakes. Therefore, the contents of Cu and Zn in Zizania are within the safe range.

Claims (8)

1. A method for recycling pig farm sewage, characterized in that anaerobic fermentation, three-stage aeration oxidation, primary biodegradation, and secondary biodegradation treatment are carried out successively, specifically comprising the following steps: (1) After the manure produced in the pig farm production process is homogenized, anaerobic fermentation is carried out; (2), the biogas slurry obtained by anaerobic fermentation is alternately aerated and oxidized in 2 sets of tertiary oxidation ponds arranged in parallel, that is, in the tertiary oxidation ponds of A district and the tertiary oxidation ponds of B district arranged in parallel; The first oxidation pond includes the first oxidation pond, the second oxidation pond and the third oxidation pond which are sequentially connected, and the oxygenation pump is arranged in the first oxidation pond, the second oxidation pond and the third oxidation pond; The specific operation of alternate aeration oxidation is as follows: the biogas slurry first enters the first oxidation pond in area A until it is full, and then begins to stand for aeration and oxidation; the biogas slurry in the first oxidation pond of area A is left for 10-15 2/3 of the supernatant in the second oxidation tank of area A enters the third oxidation tank of area A for tertiary oxidation. Aerated and oxidized for 10-15 days; when the biogas slurry in the first oxidation pond of A area begins to stand for aeration and oxidation, the biogas slurry enters the first oxidation pond of B area, and the biogas is treated according to the treatment method of the three-stage oxidation pond of A area The liquid is aerated and oxidized step by step; the three-stage oxidation tanks in A and B areas are alternately aerated and oxidized, and the dissolved oxygen in the biogas slurry is maintained at 2.5-4.5mg/L during the aeration and oxidation process; (3) Biodegradation of biogas slurry obtained through three-stage aeration oxidation; (4) The water after primary biodegradation is subjected to secondary biodegradation through the aquatic plants in the circulating water channel; (5) The water after secondary biodegradation is accumulated and discharged after reaching the discharge standard. 2. the recycling method of pig farm sewage according to claim 1 is characterized in that in step (1), the manure produced in the pig farm production process is fully homogenized in the homogeneous tank, and is heated in the biogas anaerobic fermentation tower in anaerobic fermentation. 3. The recycling method of pig farm sewage according to claim 1, characterized in that in step (3), the biogas slurry after three-stage aeration and oxidation stays in the aquatic plant field for 10-15 days to perform a biodegradation; Aquatic plants are planted in the aquatic plant field; the planting density of aquatic plants in the aquatic plant field is: 1m wide row, 0.8m narrow row, 0.6m spacing between plants, and 1400 pier per mu. 4. the recycling method of pig farm sewage according to claim 1 is characterized in that in step (4), the water through primary biodegradation is carried out secondary biodegradation in circulating water channel, and the flow velocity of water in circulating water channel is 1 -2cm/s; the circulating water channel is composed of multiple horizontal water channels, and every two adjacent horizontal water channels form a drop of 10-20cm; at least one cage is arranged in each horizontal channel, and the planting in the cage There are aquatic plants. 5. The method for recycling pig farm sewage according to claim 1, characterized in that in step (5), the secondary biodegraded water is accumulated in a settling tank, and the supernatant enters a discharge area for discharge. 6. A recycling system for pig farm sewage, characterized in that it comprises a homogeneous pond, a biogas anaerobic fermentation tower, at least two sets of parallel three-stage oxidation ponds, aquatic plant fields, and a circulation channel, and the homogeneous pond and The pig farm is connected, the homogeneous tank is connected to the biogas anaerobic fermentation tower through pipelines, and the biogas anaerobic fermentation tower is connected to the inlet of the tertiary oxidation tank. Each set of tertiary oxidation tanks includes the first oxidation tank and the second oxidation tank connected in sequence pond and the third oxidation pond; the third oxidation pond of each set of three-stage oxidation ponds leads to the aquatic plant field through pipelines, and the described aquatic plant field is connected with the circulating water channel through the water channel; the described circulating water channel is composed of multi-section horizontal The water channel is composed of two adjacent horizontal water channels forming a drop of 10-20cm, and at least one cage is arranged in each horizontal water channel; the circulating water channel is connected to the sedimentation tank; the sedimentation tank is connected to the discharge area. 7. The pig farm sewage recycling system according to claim 6, characterized in that the pig farm sewage recycling system is provided with two sets of three-stage oxidation ponds in parallel; each section of the horizontal water channel is provided with a net box. 8. The recycling system of pig farm sewage according to claim 6, characterized in that holes are provided on the slate of the water channel outside the ridge of the aquatic plant field; the third oxidation pool connected to each set of three-stage oxidation pools is characterized in that Water pumps on pipes with aquatic plants field.