Composite short-range denitrification method for aquaculture tail water treatment

Abstract

The application discloses a kind of composite short-range denitrification water culture tail water treatment methods, comprising the following steps: pretreatment: solid-liquid separation is carried out to culture tail water;Short-range denitrification treatment: after being treated by at least 2 rounds of "purification pond-filter dam", into final-stage purification pond, again by the bottom water through water partition wall in the tail of final-stage purification pond into aeration tank The processing technology, through water quality monitoring and automatic control, realize the environmental condition requirement of short-range biological denitrification: ecological treatment pond: further convert nutrient in water body by wetland organism;After being treated, culture tail water is discharged or recycled in accordance with standard.The technical method of the application can more directly and quickly remove nitrogen in tail water in the form of nitrogen gas, and has the advantages of high purification efficiency, good controllability, strong practicability, easy management, etc.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of aquaculture tail water treatment method, especially a kind of composite short-range denitrification aquaculture tail water treatment method. BACKGROUND

[0002] Aquaculture is an important part of agricultural production, and the tail water produced during the breeding process can cause harm to the surrounding water and the ecological environment, which has restricted the sustainable development of the industry, and the problem of tail water treatment technology needs to be solved urgently.

[0003] Aquaculture tail water has typical high-nitrogen characteristics, i.e., the main pollutants in the tail water are residual feed and excreta of aquatic animals, i.e., nitrogen compounds.

[0004] Currently, the main modes for treating aquaculture tail water are the "three pools and two dams" or "four pools and three dams" tail water treatment mode and the artificial wetland tail water treatment mode. The main treatment technology is to accelerate the decomposition of organic matter in the water body by biology. There are generally problems such as poor stability, poor operability, long treatment time, etc., especially low denitrification rate, incomplete water purification, and high total nitrogen content in the recycled water, which affects the reuse of tail water.

[0005] Industrial wastewater treatment technology is difficult for aquaculture farms to afford due to high investment and operating costs. Due to the disconnection between existing technology development and aquaculture application, the practicality and maturity of industrial wastewater treatment technology in the field of aquaculture tail water treatment are reduced. SUMMARY

[0006] The present application aims to provide a composite short-range denitrification aquaculture tail water treatment method. The present application controls the key environmental factors of short-range biological denitrification principle in a practical process, and combines it with the aquaculture tail water wetland ecological treatment process to propose a composite aquaculture tail water treatment method based on short-range denitrification process, plus front-end solid-liquid separation pretreatment, and back-end wetland biological treatment method. This method has high treatment efficiency, low treatment cost, and convenient management, and is especially suitable for large-volume aquaculture tail water treatment.

[0007] The technical solution of the present application is a composite short-range denitrification aquaculture tail water treatment method, comprising the following steps:

[0008] S1: Pretreatment: solid-liquid separation of aquaculture tail water;

[0009] S2: Short-range denitrification treatment: after at least 2 rounds of "purification pool-dam" treatment, enter the final purification pool, and then enter the aeration tank through the bottom water passage partition wall at the tail of the final purification pool, and realize the environmental condition requirements of short-range biological denitrification through water quality monitoring and automatic control:

[0010] S2-1. Purification pool: the pool bottom is earthy, floating aquatic plants are arranged on the water surface, and brushes are vertically arranged in the pool;

[0011] S2-2. Filter dam treatment: the filter dam is a vertical submerged dam with water flowing from bottom to top, and filter material is filled in the dam body;

[0012] S2-3. Final purification pool: water quality monitoring probes are arranged at a water depth of 40% from the pool bottom, and a plurality of aeration discs are arranged at about 30 cm from the pool bottom, automatic aeration is started when the dissolved oxygen is monitored to be lower than 0.25 mg / l, automatic aeration is stopped when the dissolved oxygen is monitored to be higher than 0.50 mg / l, and the dissolved oxygen in the middle layer of the final purification pool is maintained at 0.25-0.50 mg / l through such intermittent aeration, so as to achieve the environmental condition requirement of short-range biological denitrification;

[0013] S2-4. Bottom water passing partition wall: a partition wall with an upper part higher than the water surface and a bottom passage is arranged, so that the water body in the final purification pool directly enters the aeration tank through the lower part of the partition wall, or enters the aeration tank by overturning a partition wall drop after passing through the lower part passage of the partition wall;

[0014] S2-5. Aeration tank: aeration discs or microporous aeration pipes are laid in the aeration tank, and nitrogen overflow in the water body is accelerated through aeration;

[0015] S3: Ecological treatment pool: further conversion of nutrients in the water body by wetland organisms;

[0016] S4: After treatment of the aquaculture tail water, the treated tail water meets the discharge standard or is recycled.

[0017] In the foregoing composite short-range denitrification aquaculture tail water treatment method, the short-range denitrification treatment area of S2 is 60%-70% of the entire tail water treatment area; and the area of the ecological treatment pool of S2 is 40%-30% of the entire tail water treatment area.

[0018] In the foregoing composite short-range denitrification aquaculture tail water treatment method, the area of the floating aquatic plants in the purification pool of S2 is more than 50%; and the area of the floating aquatic plants in the final purification pool is more than 30%.

[0019] In the foregoing composite short-range denitrification aquaculture tail water treatment method, the water depth of the purification pool of S2 is greater than or equal to 2.0 meters; and the height of the filter dam in S2 is greater than or equal to 1.5 meters.

[0020] In the foregoing composite short-range denitrification aquaculture tail water treatment method, the area of the final purification pool in S2 is the largest, accounting for 40-60% of the total purification pool area.

[0021] In the aforementioned composite short-range denitrification aquaculture tail water treatment method, a sewage suction pipe is laid at the bottom of the filter dam in S2; and the purification tank and the filter dam in S2 are inoculated with a denitrification microbial community.

[0022] In the aforementioned composite short-range denitrification aquaculture tail water treatment method, the pH value of the water body in the final-stage purification tank in S2 is adjusted to 8.0-8.5 by using lime water.

[0023] In the aforementioned composite short-range denitrification aquaculture tail water treatment method, a brush area is arranged in the water body in the purification tank in S2, the area accounts for 20-30% of the area of the purification tank, and a brush is arranged at a density of one brush per 25-35 cm and is arranged in multiple places; a brush area is arranged in the water body in the final-stage purification tank, the area accounts for 20-30% of the area of the final-stage purification tank, and a brush is arranged at a density of one brush per 25-35 cm and is arranged in multiple places.

[0024] In the aforementioned composite short-range denitrification aquaculture tail water treatment method, a plurality of aeration discs are arranged in the water body in the final-stage purification tank in S2, the arrangement density is one aeration disc per 6-9 m 2 ~ 9 m 2 The arrangement area of the aeration disc accounts for more than 60% of the area of the final-stage purification tank, and the start and stop of aeration are automatically controlled according to the water quality monitoring result.

[0025] In the aforementioned composite short-range denitrification aquaculture tail water treatment method, the area of the aeration tank in S2 accounts for 5-10% of the area of the final-stage purification tank, is greater than or equal to 50 m 2 , the aeration disc is arranged at the bottom of the tank, the arrangement density is greater than or equal to 2.50 m 2 per aeration disc, and the aeration power is greater than or equal to 1.8 kw per 50 m 2 .

[0026] The beneficial effects of the present application are as follows: compared with the prior art, the traditional nitrification and denitrification reaction denitrification is carried out as follows: nitrification reaction: ammonia nitrogen--under the action of microorganisms--nitrite nitrogen--under the action of microorganisms--nitrate nitrogen; denitrification reaction: nitrate nitrogen--under the action of microorganisms--nitrite nitrogen--under the action of microorganisms--nitrogen. The short-range denitrification of the present application is relative to the traditional nitrification and denitrification denitrification, and the principle of the short-range denitrification of the present application is to let the nitrification reaction only proceed halfway, that is, to nitrite nitrogen and not to continue, but to directly carry out denitrification to generate nitrogen, which then overflows into the air.

[0027] To achieve short-range nitrification, in addition to the participation of microorganisms (denitrifying microorganisms, including nitrifying bacteria and denitrifying bacteria), the control of environmental conditions such as dissolved oxygen and ph, and the provision of sufficient microbial attachment substrate are required. The present application is mainly based on practical and convenient control to control the environmental conditions, through the setting of "purification pool-filter dam" and built-in objects, through natural biochemical evolution, the environmental conditions such as dissolved oxygen and ph are close to the required target range, and then the automatic monitoring and control system is used to regulate and control the dissolved oxygen, supplemented by manual adjustment of ph, so as to realize short-range denitrification.

[0028] When the dissolved oxygen is 0.25-0.50 mg / l, the short-range reaction can become the main reaction, otherwise the traditional nitrification-denitrification reaction will become the main reaction. When the ph value is 8.0-8.5 mg / l, it is more helpful for the short-range reaction to become the main reaction.

[0029] The technical method of the present application can more directly and quickly overflow the nitrogen in the tail water in the form of nitrogen gas, and has the advantages of high purification efficiency, good controllability, strong practicability, convenient management and the like. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 The process diagram of the present application is shown in the figure;

[0031] Fig. 2 The partial structure diagram of the present application is shown in the figure. DETAILED DESCRIPTION

[0032] The present application will be further described below in combination with examples, but it is not used as the basis for limiting the present application.

[0033] Embodiment of the present application: a composite short-range denitrification method for aquaculture tail water treatment, as shown in the figure, comprising the following steps: Figs. 1-2

[0034] (1) Pretreatment: solid-liquid separation of the aquaculture tail water is carried out through a microfilter, a sedimentation device and the like, and the solid-liquid separation can be realized by any existing technology. The tail water after solid-liquid separation is sent to the next step for treatment.

[0035] (2) Short-range denitrification treatment: after 2 rounds to multiple rounds of "purification pool-filter dam" treatment, the tail water enters the treatment process of "final-stage purification pool-bottom water passage partition-aeration tank", and the environmental conditions required for short-range biological denitrification are realized through water quality monitoring and automatic regulation and control.

[0036] (1) Purification pool: the pool bottom is a soil pool, a large proportion of floating aquatic plants are arranged on the water surface, which can absorb nutrients and block sunlight to reduce photosynthesis in the water body and thus reduce the dissolved oxygen in the water body; vertical brushes are arranged in the pool as microbial culture substrate. ​

[0037] (2) Filter dam treatment: vertical subsurface dam with water flowing from bottom to top. Filter material is filled in the dam body, which can be selected from ceramsite, volcanic rock, etc. to adsorb and filter organic matter, serve as the fixation matrix for denitrifying microorganisms, and adsorb gas in water to reduce dissolved oxygen.

[0038] (3) Circulation of "purification tank-filter dam". According to site conditions and treatment pressure, 2 to multiple rounds of continuous treatment of "purification tank-filter dam" are arranged.

[0039] (4) Final purification tank: water quality monitoring probe is arranged at 40% of water depth from the bottom of the tank, and multiple aeration discs are arranged at about 30 cm from the bottom of the tank. When the monitored dissolved oxygen is lower than 0.25 mg / l, automatic aeration is started, and when the monitored dissolved oxygen is higher than 0.50 mg / l, automatic aeration is stopped. The intermittent aeration keeps the dissolved oxygen in the middle layer of the final purification tank at 0.25-0.50 mg / l, so as to achieve the environmental condition requirement of short-range biological denitrification.

[0040] (5) Bottom water passage partition wall: the partition wall is arranged to have a 0.5 m passage at the bottom and be higher than the water surface, so that the water body in the final purification tank directly enters the aeration tank through the lower part of the partition wall, or enters the aeration tank by overturning a partition wall drop after passing through the lower passage of the partition wall.

[0041] (6) Aeration tank: aeration disc or microporous aeration pipe is laid in the aeration tank to accelerate the overflow of nitrogen in the water body.

[0042] (Three) Ecological treatment tank: further conversion of nutrients in the water body is realized by wetland organisms. Submerged plants and floating plants are planted at the bottom of the natural wetland treatment tank, emergent plants are planted around, oxygenation facilities are arranged, and a certain amount of silver carp, bighead carp, local snails and local shrimps are raised. Any existing wetland water purification technology can be used.

[0043] (Four) After the breeding tail water is treated, it can be discharged or recycled.

[0044] Step (two) short-range denitrification treatment area is 60%-70% of the entire tail water treatment area. The area of the ecological treatment tank in step (three) is 40%-30% of the entire tail water treatment area. The short-range denitrification treatment area accounts for a large proportion because the present application mainly uses short-range denitrification. After short-range denitrification, there is still a part of nitrogen in the tail water, so it is necessary to enter the ecological treatment tank to treat the remaining nitrogen by using the artificial wetland method.

[0045] The area of the floating aquatic plants in the purification pond of step (ii) is more than 50%, and the area of the floating aquatic plants in the final purification pond is more than 30%. The area of the floating aquatic plants in the purification pond of the "purification pond-filter dam" link is more than 50% in order to reduce the dissolved oxygen in the water as much as possible. The dissolved oxygen in the discharged aquaculture tail water is generally 1-3 mg / l, and the dissolved oxygen in the water is reduced through the purification pond which is shaded from sunlight to achieve the low dissolved oxygen of less than 0.50 mg / l required for short-range denitrification. The reason for setting the area of the floating aquatic plants in the final purification pond to more than 30% is that the dissolved oxygen in the water has basically reached less than 0.50 mg / l after the water is treated by the "purification pond-filter dam" link for 2-3 rounds. At this time, the final purification pond mainly plays a role in stabilizing the water quality, and many times it is also necessary to increase the oxygen for the dissolved oxygen which is too low in the previous step. Therefore, the plant area is lower than the previous one. Another reason is that a larger water surface is convenient for spraying lime water to adjust the pH value

[0046] The purification pond of step (ii): It is better to set a large proportion of floating aquatic plants on the water surface. When it is not easy to implement, it can be partially replaced by plastic and other floating industrial products.

[0047] The water depth of the purification pond of step (ii) is not less than 2.0 meters. The water depth can effectively reduce the dissolved oxygen in the water and promote the growth of denitrifying microorganisms.

[0048] The final purification pond of step (ii) has the largest area, accounting for 40-60% of the total purification pond area.

[0049] The height of the filter dam of step (ii) is not less than 1.5 meters. The water passes through the subsurface filter dam, and the microorganisms on the filter material can degrade the nutrients in the water, and the dissolved oxygen can be reduced. If the height is not enough, it will not achieve good results.

[0050] The filter dam of step (ii) is laid with a suction pipe at the bottom to regularly suck out the sediments.

[0051] In step (ii), the purification pond and the filter dam are inoculated with denitrifying microbial communities. Although a natural microbial community can be formed, artificial inoculation of denitrifying microbial communities can quickly form sufficient microbial quantities to achieve the short-range denitrification process we need. In addition, the denitrifying microbial strains (usually a combination of multiple strains) artificially inoculated are screened by humans and have high denitrification efficiency.

[0052] In the final purification pond of step (ii), lime water is used to adjust the pH value to 8.0-8.5 on a regular basis, because the pH value of 8.0-8.5 is a relatively suitable environmental condition for short-range denitrification.

[0053] In step (2), a brush area is arranged in the water body of the purification tank, the area accounts for 20-30% of the area of the purification tank, the arrangement density is one brush per 25-35 cm, and it is suitable to arrange in multiple places; a brush area is arranged in the water body of the final purification tank, the area accounts for 20-30% of the area of the final purification tank, the arrangement density is one brush per 25-35 cm, and it is suitable to arrange in multiple places, which balances the distribution of denitrifying microbial community in the purification tank and the final purification tank.

[0054] In step (2), a plurality of aerators are arranged in the water body of the final purification tank, the arrangement density is one aeration plate per 6-9 m 2 2 of the final purification tank, the arrangement area of the aerator accounts for more than 60% of the area of the final purification tank, and the start and stop of aeration are automatically controlled according to the water quality monitoring results to balance the dissolved oxygen in the water body.

[0055] In step (2), the aeration tank is a cement tank or a hardened tank paved with geotextile to avoid stirring the bottom mud during aeration.

[0056] In step (2), the area of the aeration tank is 5-10% of the area of the final purification tank, and is not less than 50 m 2 , the aerator is arranged at the bottom of the tank, the arrangement density is not less than one aeration plate per 2.50 m 2 , and the aeration power per 50 m 2 is not less than 1.8 kw, so that enough gas can be brought out of the water body to the air.​

Claims

1. A method for treating aquaculture effluent by a combined short-cut nitrogen removal process, characterized in that: It comprises the following steps: S1: Pretreatment: solid-liquid separation of aquaculture tail water; S2: Short-term nitrogen removal treatment: after at least two rounds of "purification pool-filter dam" treatment, enter the final purification pool, and then enter the aeration tank through the bottom water passage of the tail of the final purification pool, through water quality monitoring and automatic control, to achieve the environmental conditions required for short-term biological denitrification: S2-1. Purification pool: the bottom of the pool is a soil pool, floating aquatic plants are provided on the water surface, and brushes are vertically arranged in the pool; S2-2. Filter dam treatment: the filter dam is a vertical subsurface dam with water flowing from bottom to top, and filter material is filled in the dam body; S2-3. Final purification pool: water quality monitoring probes are arranged at a water depth of 40% from the bottom, and multiple aeration discs are arranged at about 30 cm from the bottom, and when the dissolved oxygen is less than 0.25 mg / l, the aeration is automatically started, and when the dissolved oxygen is more than 0.50 mg / l, the aeration is automatically turned off, and through such intermittent aeration, the dissolved oxygen in the middle layer of the final purification pool is maintained at 0.25-0.50 mg / l, to achieve the environmental conditions required for short-term biological denitrification; S2-4. Bottom water passage partition: a partition with an upper part higher than the water surface and a bottom passage is provided, so that the water body in the final purification pool directly enters the aeration tank through the lower part of the partition, or after passing through the lower passage of the partition, it jumps over a partition waterfall to enter the aeration tank; S2-5. Aeration tank: aeration discs or microporous aeration pipes are laid in the aeration tank to accelerate the overflow of nitrogen in the water body; S3: Ecological treatment pool: further conversion of nutrients in the water body by wetland organisms; S4: After treatment, the aquaculture tail water meets the discharge standard or is recycled; The short-term nitrogen removal treatment area of S2 is 60%-70% of the entire tail water treatment area; the ecological treatment pool area of S2 is 40%-30% of the entire tail water treatment area; The area of floating aquatic plants in the purification pool of S2 is more than 50%; the area of floating aquatic plants in the final purification pool is more than 30%; The water depth of the purification pool of S2 is ≥2.0 meters; the height of the filter dam of S2 is ≥1.5 meters; The area of the final purification pool of S2 is the largest, accounting for 40-60% of the total purification pool area; The filter dam bottom of S2 is paved with a sewage suction pipe; the purification pool and filter dam of S2 are inoculated with denitrification microbial communities; The water body in the final purification pool of S2 is adjusted to a ph value of 8.0-8.5 using lime water.

2. The composite short-cut de-nitrification method for treating the aquaculture tail water according to claim 1, characterized in that: The purification pool of S2 is provided with a brush area, which accounts for 20-30% of the purification pool area, and the brush area is arranged at a density of one brush per 25-35 cm and is arranged in multiple places; the final purification pool is provided with a brush area, which accounts for 20-30% of the final purification pool area, and the brush area is arranged at a density of one brush per 25-35 cm and is arranged in multiple places.

3. The composite short-cut de-nitrification method for the aquaculture tail water according to claim 1, characterized in that: The multiple aerators arranged in the water body of the final purification pool of S2 are arranged at a density of one aerator per 6 m 2 ~ 9 m 2 An aerator is arranged, the arrangement area of the aerator accounts for more than 60% of the area of the final purification pool, and the start and stop of aeration are automatically controlled according to the water quality monitoring result.

4. The composite short-cut de-nitrification method for the aquaculture tail water according to claim 1, characterized in that: The aeration tank area in S2 is 5% to 10% of the final purification tank area, ≥50 m 2 The aeration disc is arranged at the bottom of the tank, and the arrangement density is ≥2.50 m 2 One aeration disc, and the aeration power is ≥1.8 kw per 50 m 2 .

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