A multi-stage circulating ecological purification system for aquaculture tail water based on salt regulation and its operation process

Abstract

The present invention provides a multi-stage circulating ecological purification system for aquaculture tail water based on salinity regulation and its operation process. The system includes an aquaculture area, a tail water purification area, a water quality improvement area, an electric sluice, a make-up water regulation pond, a reflux system and an effluent regulation pond. The tail water in the aquaculture area passes through the purification area and is first purified by filter-feeding salt-tolerant fish, and then undergoes secondary purification through salt-tolerant ecological waterweeds, ultrafine bubble equipment, microbial agents and filter-feeding salt-tolerant fish in the water inlet area of the water quality improvement area. Finally, it is detected by the water quality monitoring electric sluice in the water outlet area of the water quality improvement area. If the water quality does not meet the standard, the reflux system is activated to purify the water body again; if the water quality meets the standard, it is determined by the numerical control center: if the system needs to make up water, the water body is introduced into the make-up water regulation pond, and after adjusting the salinity, it is transported to the aquaculture area; if the system faces a sharp rise in water level, the water body is introduced into the effluent regulation pond, and after diluting the water body concentration, it is discharged into the river. The present invention circulates and purifies aquaculture tail water through the comprehensive synergistic action of physics and biology, which is safe and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the field of ecological treatment of aquaculture tail water, and particularly relates to a multi-stage circulating ecological purification system for aquaculture tail water based on salinity regulation. Background Art

[0002] During the production process of the aquaculture industry, water pollution caused is a very common problem. There are many reasons for the pollution. For example, the breeding density is too high, the feeding method of bait is unscientific or the feeding amount is too large, the use of drugs in the fishery production process does not meet the requirements, etc. It will inevitably cause a certain degree of damage to the water environment and deteriorate the living environment of aquatic products in the aquaculture waters. The reasons for water pollution caused by aquaculture are: 1. The COD concentration is low, 2. The total nitrogen and ammonia nitrogen contents are high, 3. The one-time output of tail water is large. Especially when it comes to the cultivation of white shrimp, the situation of too high salinity of tail water will also be encountered.

[0003] For traditional aquaculture tail water treatment methods, generally a large amount of chemical reagents need to be added, and a separate treatment pool needs to be built, which occupies a large area. At the same time, the potential safety hazards are also very significant. The treated wastewater is directly poured into the river without a resource utilization process. The investment cost is high, there is no economic benefit, and it does not conform to the concept of environmental protection.

[0004] The Chinese patent authorization document "An Environmentally Friendly Aquaculture Tail Water Treatment Device" with the application number CN202222051530 is characterized in that it is a device used for treating the tail water containing fecal impurities generated by aquaculture, which plays a role in filtering and purifying the tail water and is applied to various aquaculture occasions; it aims to improve that usually the device will be used in combination with hydroponic cultivation during tail water treatment, but the tubular hydroponic cultivation results in a small water receiving area during hydroponics, making it impossible for hydroponic plants to absorb nutrients more fully, and the filtering effect increased by hydroponics is also poor. After a long time of hydroponics, maintenance and cleaning are also required, resulting in the inability to carry out water treatment and hydroponic use environmentally friendly. However, this device still needs to use a large amount of fresh water resources for cleaning and maintenance, and the subsequent cleaning wastewater is difficult to be utilized, easily causing waste of resources.

[0005] The Chinese patent authorization document "A Pond Land-Based Tail Water Treatment System" with the application number CN202222844450 is characterized in that it includes a physical filtration pool, an electrocatalytic filtration pool, an aeration filtration pool and a biological filtration pool, which aims to effectively remove reducing substances in water including organic matter, nitrite, ferrous salt, sulfide, etc., as well as the main pollutants in freshwater pond aquaculture tail water including chemical oxygen demand COD, ammonia nitrogen content index NH3-N, total nitrogen TN, total phosphorus TP, suspended solids SS and other substances. However, the physical filtration pool and electrocatalytic filtration pool of this device consume a high amount of power resources, have a large investment cost, and require manual maintenance, resulting in a large later maintenance and operation cost, which is uneconomical and impractical.

[0006] The Chinese patent authorization document "Fishery Aquaculture Tail Water Treatment System" with the application number CN202222270327 is characterized in that in the fishery aquaculture tail water treatment system, a biological treatment branch and a reflux branch are simultaneously set. The tail water in the pond is diverted to the biological treatment branch and the reflux branch. Part of the tail water passes through the biological treatment branch and is purified. After the ammonia nitrogen concentration is reduced, it flows back to the pond. The other part of the tail water directly flows back to the pond through the reflux branch. While purifying the tail water, it can maintain the relative stability of the water quality, avoid the sharp change of the water quality in the pond, and thus reduce the risk of stress reaction and death of aquatic products. This system has a large floor area, and the investment and operation cost of treating tail water by combining aerobic and anaerobic methods is relatively high and not economical. Moreover, it does not consider how to handle the situation of sudden heavy rain and large water flow, which is not rigorous enough.

[0007] The Chinese patent application document "An Aquaculture Tail Water Treatment System and Treatment Method" with the application number CN202111387916 is characterized in that the treatment system includes a sedimentation area, a filtration area and a filter-feeding animal treatment area. Among them, a composite bacterial community composed of Rhodospirillum rubrum, Rhodobacter capsulatus, Rhodopseudomonas palustris and Rhodotorula mucilaginosa is added to the filter-feeding animal treatment area. This invention screens the optimal proportion of microorganisms and combines the optimal proportion of microorganisms with filter-feeding animals to treat aquaculture tail water. The composite bacterial agent is combined with filter-feeding animals, and the effect is verified to be good through pilot-scale experiments. This invention develops a composite microecological preparation mainly composed of photosynthetic bacteria, and combines filter-feeding shellfish to treat aquaculture tail water to achieve good results. This invention does not consider the situation of insufficient treatment effect caused by excessive water flow and system overload when sudden heavy rain occurs, and has great limitations in application. Summary of the Invention

[0008] In order to overcome the shortcomings of the prior art, solve the pollution problem of aquaculture tail water at the same time, and achieve integrated cyclic purification, the present invention provides a multi-stage cyclic ecological purification system for aquaculture tail water based on salinity regulation and its operation process. The filter-feeding salt-tolerant fish put in the tail water purification area can purify the tail water in the aquaculture area once, and then through the salt-tolerant ecological water plants, ultra-microbubble devices, microbial agents and filter-feeding salt-tolerant fish in the water quality improvement area, the tail water is comprehensively purified for the second time. Finally, the water quality detection electric gate and the reflux system can effectively ensure the final treatment effect, and the water replenishment adjustment pool can achieve the recycling of water resources, and the water outlet adjustment pool can make up for the emergencies encountered in sudden situations, forming an integrated, ecological, economic, safe and reliable cyclic purification system. The later salt-tolerant ecological water plants and the bottom mud generated by fish feces at the bottom of the pond can also be recycled and sold as feed, agricultural fertilizer or reused.

[0009] Meanwhile, the purification system recycles the tail water resources. The subsequent sale of filter-feeding salt-tolerant fish can provide certain economic benefits, maximizing the utilization of aquaculture tail water, which is economical and practical. In the later stage, the sludge generated by fish farming and the aquatic plants at the bottom of the water in the purification system can also be used for composting or sold, accelerating the capital return.

[0010] Technical solution

[0011] A multi-stage circulating ecological purification system for aquaculture tail water based on salinity regulation. The system includes a farming area (1), a tail water purification area (2), a water quality improvement area (3), an electric gate module (4), a makeup water adjustment tank (5), a reflux system (6) and an effluent adjustment tank (7). Electric gates and water level salinity meters are provided between or within these areas and are connected to a numerical control center to transmit the detected real-time data to the numerical control center, and the numerical control center controls the operation of each system.

[0012] The tail water purification area (2) is separated from the farming area (1) by a ridge. A connecting pipe with a connecting valve is provided in the ridge to introduce the sewage in the farming area (1) into the tail water purification area (2) and establish a hydraulic connection between the areas.

[0013] The output end of the tail water purification area (2) is connected to the water quality improvement area to receive and secondary purify the tail water and perform subsequent shunt treatment. The output end of the water quality improvement area (3) is simultaneously connected to the makeup water adjustment tank (5) and the effluent adjustment tank (7). According to the load of the system, the system controls the direction of the purified effluent.

[0014] The makeup water adjustment tank (5) is connected to the farming area (1) through a pipe with an electric gate and a makeup water pump, and is used to transport the purified water in the makeup water adjustment tank (5) to the farming area when needed.

[0015] A water level salinity meter (7-2) is provided inside the effluent adjustment tank (7), and a water quality monitoring electric gate (4-11) is provided at the outlet. After diluting the tail water to the standard concentration through a water pipe, it is discharged into the river.

[0016] The reflux system is connected to the water quality improvement area (3) through a reflux pipe with a reflux pump, and is used to pump the unqualified tail water to the water quality improvement area (3) for re-purification, forming a circulating purification system.

[0017] The farming area (1) is divided into more than one farming block, and each farming block is provided with a corresponding tail water purification block for the primary purification of aquaculture tail water. The farming blocks and the tail water purification blocks are separated by ridges, and connecting pipes are provided in the middle of the ridges to introduce the farming blocks into the tail water purification blocks and establish a hydraulic connection within the blocks.

[0018] At most, one tail water purification area is connected to two aquaculture blocks. Filter-feeding salt-tolerant fish are released in the tail water purification area, and the pollutants concentration in the aquaculture tail water is reduced by the gill rakers of the filter-feeding salt-tolerant fish.

[0019] A water level and salinity monitor is installed in each aquaculture block to monitor the water level and water salinity content in the aquaculture area (1). At the same time, an aerator should be installed at the bottom of each aquaculture block to evenly mix the water body in the aquaculture area and increase the dissolved oxygen content in the water body of the aquaculture area.

[0020] The water quality improvement area is divided into three parts. The first two are the water inlet areas, namely the water quality improvement area 3-1 and the water quality improvement area 3-2 in sequence. The last one is the water outlet area, that is, the water quality improvement area 3-3. The three are arranged staggered in sequence. An electric gate with a water quality monitoring device is set at the end of the water outlet area, which is the area for further purifying and discharging the up-to-standard tail water. Salt-tolerant ecological waterweeds (3-4) are planted at the bottom of the water quality improvement area (3), an ultra-micro bubble device (3-5) is installed at the bottom, and filter-feeding salt-tolerant fish are released into the water body, and their synergistic effect reduces the pollutants concentration.

[0021] The electric gate module (4) includes electric gates set between each area in the water quality improvement area, the electric gate at the end of the water outlet area of the water quality improvement area, the return water outlet electric gate set at the end of the return system (6), and the electric gates set between the water replenishment and regulation pool (5) and the aquaculture area. The water quality monitoring electric gate at the end of the water outlet regulation pool is used to control the discharge of tail water into the river.

[0022] A water quality regulation salt tank and a water level and salinity monitor (5-7) are arranged in the water replenishment and regulation pool (5). Suitable salts for the growth of whiteleg shrimp are stored in the salt tank, and the numerical control center regulates the salt dosage to adjust the salinity of the water body in the water replenishment and regulation pool (5); the water level and salinity monitor monitors the water level and salinity of the water body; an air-flow type stirring device is installed in the water replenishment and regulation pool (5).

[0023] Based on the operation process of a multi-stage circulating ecological purification system for aquaculture tail water based on salinity regulation, the process is as follows:

[0024] (1) The tail water in the aquaculture area passes through the purification area, and the filter-feeding salt-tolerant fish purify the tail water in the aquaculture area once.

[0025] (2) The purified tail water passes through the salt-tolerant ecological waterweeds, ultra-micro bubble device, microbial inoculum and filter-feeding salt-tolerant fish in the water inlet area of the water quality improvement area, and the tail water is purified for the second time.

[0026] (3) The purified tail water is detected by the water quality monitoring electric gate in the water outlet area of the water quality improvement area. If the water quality does not meet the standard, the reflux system is activated to purify the water body again; if the water quality meets the standard, it is determined by the numerical control center. If the system needs to replenish water, the water body is introduced into the water replenishment adjustment pool, and after adjusting the salinity, it is transported to the aquaculture area; if the system is threatened by a sharp rise in water level, the water body is introduced into the water outlet adjustment pool, and after diluting the water body concentration, it is discharged into the river.

[0027] The operation process of the above-mentioned multi-stage circulating ecological purification system for aquaculture tail water with salinity regulation is as follows:

[0028] The first step: Estimate the total volume V1 and depth H1 of the aquaculture area (1) after completion, as well as the volume V2 and depth H2 of the water outlet area of the water quality improvement area, and calculate and determine the following supporting facility parameters;

[0029] The volume V3 of the water replenishment adjustment pool (5), the water pump flow rate Q1 of the water replenishment pump, the water pump flow rate Q2 of the reflux pump, and the volume V4 of the water outlet adjustment pool;

[0030]

[0031] In the formula:

[0032] V3: The volume of the water replenishment adjustment pool, m 3 ;

[0033] α: The safety magnification factor, generally taking 1 - 1.2;

[0034] β: The early warning water level margin, generally taking 1% - 5%;

[0035] H1: The depth of the aquaculture area, m;

[0036] H 1MIN : The critical minimum value of the aquaculture area water level, generally taking 1.5 m or 2 / 3 of the aquaculture area water level in the cultivation of Litopenaeus vannamei, m;

[0037] V1: The total volume of the aquaculture area, m 3 ;

[0038]

[0039] In the formula:

[0040] Q1: The water pump flow rate of the water replenishment pump, m 3 / h;

[0041] V3: The volume of the water replenishment adjustment pool, m 3 ;

[0042] t1: The water replenishment time, which is determined according to the actual situation of the aquaculture area volume. If the value is too small, it is easy to cause stress reactions in Litopenaeus vannamei during water replenishment, h;

[0043]

[0044] In the formula:

[0045] Q2: water pump flow rate of the return pump, m3 / h;

[0046] H2: depth of the water outlet area in the water quality improvement area, m;

[0047] β: early warning water level margin, generally taking 1% - 5%;

[0048] H 2MIN : water level critical value of the water outlet area in the water quality improvement area, determined according to the situation of planting salt-tolerant aquatic plants, m;

[0049] V2: volume of the water outlet area in the water quality improvement area, m 3 ;

[0050] t2: return time, h;

[0051]

[0052] V4: volume of the water outlet regulating tank, m 3 ;

[0053] α: safety magnification factor, generally taking 1 - 1.2;

[0054] β: early warning water level margin, generally taking 1% - 5%;

[0055] H 2MIN : minimum water level critical value of the water outlet area in the water quality improvement area, determined according to the situation of planting salt-tolerant aquatic plants, m;

[0056] V2: volume of the water outlet area in the water quality improvement area, m 3 ;

[0057] Step 2: Start the purification process of the system according to the climate conditions

[0058] (1) When the climate is hot and dry or humid with little rainfall, the characteristics of the tail water at this time are small water flow and high pollutant concentration. The numerical control center normally takes corresponding measures according to the climate characteristics;

[0059] A. The water body in the aquaculture area (1) flows into the tail water purification area (2) for purification

[0060] B. The numerical control center passes the water at the end of the tail water purification area into the water quality improvement area by adjusting the connection valve on the connecting pipe. After passing through the salt-tolerant ecological aquatic plants and the ultra-micro bubble equipment (and further reducing the pollutant concentration by adding microbial agents and filter-feeding salt-tolerant fish, and controlling the water level by adjusting the gate;

[0061] C. When the water body reaches the water quality monitoring electric sluice at the end of the third water quality improvement area (3-3), the water quality is judged first. The water quality judgment standard is C0:

[0062] C > C0

[0063] In the formula:

[0064] C: is the concentration of pollutants in the water body at this time, mg / L;

[0065] C0: is the discharge standard of aquaculture tail water, mg / L;

[0066] The discharge standard C0 of aquaculture tail water includes the discharge concentration standards of various pollutants. As long as one of the pollutant concentrations C in the water body satisfies the above formula C > C0, the output of this formula is truth; otherwise, the output is false.

[0067] D. If the output is truth, it means that the water quality does not meet the standard. Then, the water body is transported to the front end of the first water quality improvement area (3-1) through the reflux system (6) for re-purification until it meets the standard.

[0068] E. If the output is false, it means that the water quality meets the standard. Due to the influence of water surface evaporation on the water body in the system, the overall water level in the system is in a downward trend. At this time, the aquaculture area needs to supplement water regularly. Then, the electric sluice is opened, and the purified and up-to-standard water body flows from the third water quality improvement area (3-3) to the water replenishment regulation pool (5).

[0069] F. The water level of the water replenishment regulation pool is approaching the critical maximum value H 3MAX which can be determined by the following formula:

[0070]

[0071] In the formula:

[0072] H 3MAX : is the water level of the water replenishment regulation pool approaching the critical maximum value, m;

[0073] H3: is the depth of the water replenishment regulation pool, m;

[0074] β: is the early warning water level margin, generally taking 1% - 5%;

[0075] χ: is the main water quality influencing factor in the water body;

[0076] The main water quality influencing factor χ can be determined by the following formula:

[0077]

[0078] In the formula:

[0079] C: Pollutant concentration of water body at this time, mg / L;

[0080] C0: Discharge standard of aquaculture tail water, mg / L;

[0081] ρ: Salinity in water body at this time, %;

[0082] ρ1: Set aquaculture salinity in aquaculture area, %;

[0083] When the numerical control center receives that the water level of the water replenishment regulation pond is approaching the critical maximum value H 3MAX or the water level of the third water quality improvement area (3 - 3) drops to H 2MIN , at this time, the electric gate is closed. When the numerical control center receives that the water level of the aquaculture area is approaching the critical minimum value H 1MIN or the water replenishment regulation pond reaches the preset regular water replenishment time, immediately turn on the groundwater feed pump, water quality regulation salt tank and air - flow stirring device. After the water body in the pond is adjusted in concentration, the water body is supplemented into the aquaculture area (1) through the electric gate and the water replenishment pump until the water level in the aquaculture area (1) reaches the critical maximum value H 1MAX , value:

[0084] H 1MAX =(1 - β)×H1;

[0085] G. If the water quality of the third water quality improvement area (3 - 3) meets the standard, and the water replenishment regulation pond is working or the water level has reached the critical maximum value H 3MAX of the water level of the water replenishment regulation pond. At this time, if the water level of the third water quality improvement area (3 - 3) is approaching the critical maximum value H 2MAX of the water level of the third water quality improvement area (3 - 3), that is:

[0086] H 2现状 =H 2MAX =(1 - β)×H2

[0087] Then there is no lack of water in the system, and even the water source is sufficient; the electric gate of water quality monitoring is opened, and the purified and qualified water body flows from the third water quality improvement area (3 - 3) to the water outlet regulation pond (7), and the following judgment is made:

[0088]

[0089] H 4现状 ≥H 4MAX =H4×(1 - β)(χ0≤1)

[0090]

[0091] In the formula:

[0092] H 4现状 : Current water level of the water outlet regulation pond, m;

[0093] H 2现状 : is the current water level of the outlet area of ​​the water quality improvement area, m;

[0094] β: It is the margin of the early warning water level, generally 1% to 5%;

[0095] χ0: the main factors affecting water quality in the discharged water body;

[0096] H 2MAX : is the critical maximum water level of the outlet area of ​​the water quality improvement area, m;

[0097] H 2MIN : is the critical minimum water level in the outlet area of ​​the water quality improvement area, which is determined according to the planting conditions of salt-tolerant grass, m;

[0098] The main water quality influencing factor χ0 of this formula can be determined by the following formula:

[0099]

[0100] Where:

[0101] C: is the concentration of pollutants in the water at this time, mg / L;

[0102] C0: aquaculture tailwater discharge standard, mg / L;

[0103] ρ: salinity in the water at this time, %;

[0104] ρ0: The salinity of tailwater from aquaculture ponds located in non-saline-alkali soil areas is required to be 1%.

[0105] H. If the output is truth, the water quality monitoring electric gate is closed, and the water body is diluted to the standard concentration through the water supply pipe in the outlet regulating tank (7), the water level salinity meter and the water quality monitoring electric gate at the outlet of the outlet regulating tank (7). After the monitoring data of the three are coordinated and cooperated, the water quality monitoring electric gate is opened to discharge the tail water into the river;

[0106] Emergency I: When the water quality of the third water quality improvement zone (3-3) does not meet the standard, and the water level of the third water quality improvement zone (3-3) is close to the critical maximum value H of the water level of the third water quality improvement zone (3-3) 2MAX When the water quality still does not meet the standard after the return system (6) starts working, and because the water level in the water quality improvement zone (3) is at the critical water level, the water level in the third water quality improvement zone (3-3) is once again close to the critical maximum water level value H of the third water quality improvement zone (3-3). 2MAX When an error occurs, an alarm is immediately sent to the CNC center, and manual troubleshooting is required;

[0107] Meanwhile, the electric water quality monitoring sluice (4-10) is opened, and the water body that still fails to meet the standards after purification flows from the third water quality improvement area (3-3) to the effluent regulating tank (7), and a determination is made:

[0108]

[0109] H 4现状 ≥H 4MAX =H4×(1-β)(χ0≤1)

[0110]

[0111] In the formula:

[0112] H 4现状 : is the current water level of the effluent regulating tank, m;

[0113] H 2现状 : is the current water level of the water outlet area of the water quality improvement area, m;

[0114] β: is the early warning water level margin, generally taking 1% - 5%;

[0115] χ0: is the main water quality influencing factor in the discharged water body;

[0116] H 2MAX : is the critical maximum water level of the water outlet area of the water quality improvement area, m;

[0117] H 2MIN : is the critical minimum water level of the water outlet area of the water quality improvement area, and the value is taken according to the situation of planting salt-tolerant water plants, m;

[0118] The main water quality influencing factor χ0 of this formula can be determined by the following formula:

[0119]

[0120] In the formula:

[0121] C: is the concentration of pollutants in the water body at this time, mg / L;

[0122] C0: is the discharge standard of aquaculture tail water, mg / L;

[0123] ρ: is the salinity in the water body at this time, %;

[0124] ρ0: is the salinity of aquaculture pond tail water in non-saline-alkali soil areas for discharge requirements, taking 1, %;

[0125] When the output is "truth", the water quality monitoring electric valve is closed. Through the water supply pipe, water level and salinity meter in the effluent regulating pond (7), and the water quality monitoring electric valve at the outlet of the effluent regulating pond, the monitoring data of the three cooperate to dilute the water body to the standard concentration, and then the water quality monitoring electric valve (4-11) is opened to discharge the tail water into the river.

[0126] (2) In case of heavy rain and sudden rise of water level, the characteristics of the tail water at this time are large water flow and small pollutant concentration. The numerical control center adopts a rainstorm warning system according to the climate characteristics;

[0127] A. The aerator installed at the bottom of the aquaculture area (1) is turned on, and part of the water body in the aquaculture area (1) flows into the tail water purification area (2) for purification;

[0128] B. Due to the large flow, most of the water will enter the water inlet areas (3-1, 3-2) of the water quality improvement area through overflow; the flow in the water quality improvement area is large, and the water level is controlled by the gate adjustment; the numerical control center adjusts the connecting valve on the connecting pipe to introduce the water at the end of the tail water purification area into the water inlet area of the water quality improvement area. After passing through the salt-tolerant ecological water plants and the ultra-micro bubble equipment, and by adding microbial agents and filter-feeding salt-tolerant fish, the pollutant concentration is further reduced, and the water level is controlled by the gate adjustment;

[0129] C. When the water body flows to the water quality monitoring electric valve set at the end of the third water quality improvement area (3-3), the water quality is judged first. The water quality judgment standard is C0:

[0130] C > C0

[0131] In the formula:

[0132] C: is the pollutant concentration of the water body at this time, mg / L;

[0133] C0: is the discharge standard of aquaculture tail water, mg / L;

[0134] The discharge standard C0 of aquaculture tail water includes the discharge concentration standards of various pollutants. As long as one of the pollutant concentrations C of the water body satisfies the above formula C > C0, the output of this formula is "truth", otherwise the output is "false";

[0135] D. If the output is "truth", it means that the water quality does not meet the standard, and then the water body is transported to the front end of the first water quality improvement area (3-1) through the reflux system (6) for re-purification until it meets the standard;

[0136] Emergency situation E. If after the above step D, the water quality still does not meet the standard, and since the water levels in the water quality improvement area (3) are all at the critical water level, and the water level in the third water quality improvement area (3-3) is on the verge of the critical maximum value H of the water level in the third water quality improvement area (3-3) 2MAXImmediately send an alarm to the numerical control center and request manual troubleshooting of the cause;

[0137] At the same time, the water quality monitoring electric valve is opened, and the water body that still does not meet the standard after purification flows from the third water quality improvement area (3-3) to the outlet regulating tank (7), and the following judgment is made:

[0138]

[0139] H 4现状 ≥H 4MAX = H4×(1-β)(χ0≤1)

[0140]

[0141] In the formula:

[0142] H 4现状 : is the current water level of the outlet regulating tank, m;

[0143] H 2现状 : is the current water level of the water outlet area of the water quality improvement area, m;

[0144] β: is the early warning water level margin, generally taking 1% - 5%;

[0145] χ0: is the main water quality influencing factor in the discharged water body;

[0146] H 2MAX : is the critical maximum water level of the water outlet area of the water quality improvement area, m;

[0147] H 2MIN : is the critical minimum water level of the water outlet area of the water quality improvement area, and the value is taken according to the situation of planting salt-tolerant aquatic plants, m;

[0148] The main water quality influencing factor χ0 of this formula can be determined by the following formula:

[0149]

[0150] In the formula:

[0151] C: is the concentration of pollutants in the water body at this time, mg / L;

[0152] C0: is the discharge standard of aquaculture tail water, mg / L;

[0153] ρ: is the salinity in the water body at this time, %;

[0154] ρ0: is the salinity of aquaculture pond tail water required for discharge in non-saline-alkali soil areas, taking 1, %;

[0155] When the output is "truth", close the water quality monitoring electric valve (4-10). Through the water supply pipe, water level and salinity meter in the effluent regulation tank (7) and the water quality monitoring electric valve installed at the outlet of the effluent regulation tank, and through the coordinated cooperation of the monitoring data of the three, dilute the water body to the standard concentration, then open the water quality monitoring electric valve and discharge the tail water into the river;

[0156] F. If the output of the water body in the third water quality improvement area (3-3) is "false", it means that the water quality meets the standard. Since there is sufficient water source in the system and no water replenishment is required, open the water quality monitoring electric valve and discharge the water body until the water quality does not meet the standard, or Close the water quality monitoring electric valve again.

[0157] To sum up, the system includes a farming area, a tail water purification area, a water quality improvement area, electric valves, a water replenishment regulation tank, a reflux system and an effluent regulation tank. The tail water of the farming area passes through the tail water purification area and is purified once by the filter-feeding salt-tolerant fish in the tail water purification area. Then the tail water passes through the water quality improvement area, and through the salt-tolerant ecological water plants, ultrafine bubble equipment, microbial agents and filter-feeding salt-tolerant fish in the water inlet area of the water quality improvement area, the concentration of pollutants in the tail water is further reduced. Finally, it is detected by the water quality monitoring electric valve at the end of the water outlet area of the water quality improvement area. If the water quality does not meet the standard, the reflux system is started to pass the water body into the front section of the first water quality improvement area for purification again; if the water quality meets the standard, it is judged by the numerical control center. If the system needs to replenish water, the water body is passed into the water replenishment regulation tank, and after adjusting the salinity, it is transported into the farming area; if the system is threatened by a sharp rise in water level at this time, the water body is passed into the effluent regulation tank, and after diluting the water body to a suitable discharge concentration, it is discharged into the river. The present invention purifies the aquaculture tail water cyclically by physical and biological methods, which is safe and environmentally friendly; at the same time, the purification system recycles the tail water resources, and the subsequent sale of filter-feeding salt-tolerant fish can provide certain economic benefits, maximizing the utilization of aquaculture tail water resources, being economic and practical; the sludge generated by fish farming and the underwater water plants in the later purification system can also be used for composting or selling the water plants to accelerate the return of funds.

[0158] Compared with the prior art, the advantages of the present invention are as follows:

[0159] (1) The method has a moderate floor area and moderate upfront investment and operating costs, and is relatively cost-effective.

[0160] (2) The system uses pure physical and biological methods without adding chemical agents, which is safe and environmentally friendly. When realizing the integration of aquaculture and tail water treatment, there is no need to worry about potential safety hazards caused by chemical agents to the aquaculture objects.

[0161] (3) The system adopts the filter-feeding salt-tolerant fish purification technology, which can not only purify and improve the water quality, but also realize the resource utilization of tail water and the fish can generate certain economic benefits.

[0162] (4) The salt-tolerant ecological aquatic plants can be regularly harvested as feed and agricultural fertilizers, and the fish feces and sediment can also be used for composting, with a high degree of resource utilization, which fits the theme of environmental protection.

[0163] (5) This method adopts a circulating purification system, with a high purification degree and little harm to the river, and can be discharged with confidence.

[0164] (6) This method truly takes into account aquatic organisms in semi-saline aquaculture such as whiteleg shrimp. While recycling water, the water salinity in different areas of the system is ensured through automation. Description of the Drawings

[0165] Figure 1 It is a plan view of the aquaculture tail water purification system;

[0166] Figure 2 It is Figure 1 A sectional view along line a-a;

[0167] Figure 3 It is Figure 1 A sectional view along line b-b;

[0168] Figure 4 It is Figure 1 A sectional view along line c-c;

[0169] Figure 5 It is Figure 1 A sectional view along line d-d;

[0170] Figure 6 It is Figure 1 A sectional view along line e-e;

[0171] Figure 7 It is Figure 1 A sectional view along line f-f;

[0172] Figure 8 It is the schematic diagram of the aquaculture tail water purification system;

[0173] In the figure: aquaculture area 1, tail water purification area 2, water quality improvement area 3, electric sluice 4, make-up water regulating pool 5, reflux system 6, effluent regulating pool 7;

[0174] 1-1 - Aquaculture Area 1, 1-2 - Aquaculture Area 2, 1-3 - Aquaculture Area 3, 1-4 - Aquaculture Area 4;

[0175] Make-up water pump for Aquaculture Area 1 1-1-1, make-up water pump for Aquaculture Area 2 1-2-1, make-up water pump for Aquaculture Area 3 1-3-1, make-up water pump for Aquaculture Area 4 1-4-1;

[0176] Water level and salinity monitor 1-1-2 in Aquaculture Area 1, water level and salinity monitor 1-2-2 in Aquaculture Area 2, water level and salinity monitor 1-3-2 in Aquaculture Area 3, water level and salinity monitor 1-4-2 in Aquaculture Area 4;

[0177] Connecting pipe 1-1-3 in Aquaculture Area 1, connecting pipe 1-2-3 in Aquaculture Area 2, connecting pipe 1-3-3 in Aquaculture Area 3, connecting pipe 1-4-3 in Aquaculture Area 4;

[0178] Tail water purification area 1 2-1, tail water purification area 2 2-2, tail water purification area 3 2-3, tail water purification area 4 2-4;

[0179] Connecting pipe Ⅰ 2-1-1, connecting pipe Ⅱ 2-2-1, connecting pipe Ⅲ 2-3-1, connecting pipe Ⅳ 2-4-1;

[0180] Water quality improvement area 1 3-1, water quality improvement area 2 3-2, water quality improvement area 3 3-3;

[0181] Salt-tolerant ecological waterweeds 3-4, ultra-microbubble equipment 3-5, filter-feeding salt-tolerant fish 3-6;

[0182] Return effluent electric sluice 4-1; electric sluice 4-2, electric sluice 4-3, electric sluice 4-4, electric sluice 4-5, electric sluice 4-6, electric sluice 4-7, electric sluice 4-8;

[0183] Return influent electric sluice 4-9, water quality monitoring electric sluice 4-10, water quality monitoring electric sluice 4-11;

[0184] Feed pump Ⅰ 5-1, feed pump Ⅱ 5-2;

[0185] Water quality adjustment salt tank Ⅰ 5-3, water quality adjustment salt tank Ⅱ 5-4, water quality adjustment salt tank Ⅲ 5-5, water quality adjustment salt tank Ⅳ 5-6;

[0186] Water level and salinity monitor 5-7;

[0187] Airflow stirring device Ⅰ 5-8, airflow stirring device Ⅱ 5-9;

[0188] Return pipe Ⅰ 6-1, return pump Ⅱ 6-2;

[0189] Water supply pipe - 7-1, water level and salinity meter - 7-2. Specific implementation mode

[0190] The technical solutions of the present invention are introduced in detail below in conjunction with the accompanying drawings and specific embodiments. The present invention takes the tail water volume of the tail water body as the core. Therefore, different countermeasures are taken for the tail water with different water volumes generated in the aquaculture areas in the embodiments.

[0191] The system includes a farming area 1, a tail water purification area 2, a water quality improvement area 3, an electric sluice 4, a make-up water regulation pond 5, a reflux system 6, and an effluent regulation pond 7. All electronic devices such as electric sluices and water level and salinity meters transmit data to the numerical control center, which overall controls the electronic devices in the system.

[0192] The farming area is divided into n farming blocks, and each farming block is correspondingly provided with a tail water purification block. Filter-feeding salt-tolerant fish are put in each tail water purification area. The filter-feeding salt-tolerant fish use gill rakers to filter tiny plankton, bacteria, organic debris, etc. in the water for primary purification of the aquaculture tail water, so as to reduce the concentration of pollutants in the aquaculture tail water. The farming blocks and the tail water purification blocks are separated by dikes, and connecting pipes are provided in the middle of the dikes, through which the farming blocks can be connected to the tail water purification blocks to establish the hydraulic connection within the blocks.

[0193] Water level and salinity monitors are installed in each farming block for monitoring water level and water salinity. At the same time, aerators should be installed at the bottom of each farming block to evenly mix the water body in the farming area and increase the dissolved oxygen content in the water body in the farming area.

[0194] In the following embodiments, the number of partitions in the farming area is taken as 4, that is, n = 4. As Figure 1 described, there are a total of 4 farming blocks (Farming Area 1-1, Farming Area 1-2, Farming Area 1-3, Farming Area 1-4), and each farming block has a corresponding tail water purification block (Tail Water Purification Area 2-1, Tail Water Purification Area 2-2, Tail Water Purification Area 2-3, Tail Water Purification Area 2-4). Connecting pipes (Connecting Pipe I 2-1-1, Connecting Pipe II 2-2-1, Connecting Pipe III 2-3-1, Connecting Pipe IV 2-4-1) are provided between the farming blocks and the tail water purification blocks.

[0195] According to the regulations of the Discharge Standard of Aquaculture Tail Water in Ponds in Jiangsu Province (DB32 / 4043-2021), for the discharge limit of aquaculture tail water in freshwater receiving waters at the first level, C0 total nitrogen ≤ 3.0 mg / L, total phosphorus ≤ 0.4 mg / L, permanganate index ≤ 15 mg / L, and for other discharge requirements, the salinity ρ0 of the aquaculture pond tail water in non-saline-alkali soil areas should not be greater than 1.

[0196] The following embodiments take the farming of whiteleg shrimp as an example. The filter-feeding salt-tolerant fish selected is Barbus capito. Juvenile fish feed on zooplankton and small benthic invertebrates, and adult fish feed on small invertebrates, fish, and larvae. Adult fish need to be fed a certain amount of bait. The salt-tolerant ecological waterweed selected is Ceratophyllum demersum. According to relevant literature, the highest salinity tolerance of Ceratophyllum demersum is 6%, so the water salinity in the farming area is set to 4% in this embodiment.

[0197] Due to the relatively low hardness of the water source in the example area, calcium chloride and magnesium chloride are blended in the water quality adjustment salt tank in the ratio of sodium chloride:calcium chloride:magnesium chloride = 50:1:1 to increase the concentration of calcium and magnesium ions in the supplementary water source and provide nutrition for Litopenaeus vannamei.

[0198] Step 1: After measurement, the total volume V1 of aquaculture area 1 after completion is approximately 8320 m 3 and the depth H1 of the aquaculture area is approximately 2.11 m, and the volume V2 of the water outlet area of the water quality improvement area is approximately 930 m 3 and the depth H2 is approximately 2.5 m. The following supporting facility parameters are determined according to the calculation.

[0199] The water replenishment regulation pool 5 has four pipelines leading to the aquaculture area for the water replenishment process. Each pipeline has a corresponding electric valve and water replenishment pump, which are responsible for transporting the water body in the water replenishment regulation pool to the corresponding aquaculture block. The volume V3 of the water replenishment regulation pool 5, the water pump flow rate Q1 of the water replenishment pump, the water pump flow rate Q2 of the reflux pump, and the volume V4 of the water outlet regulation pool. Then there are the following relationships:

[0200]

[0201] In the formula:

[0202] V3: is the volume of the water replenishment regulation pool, m 3 ;

[0203] α: is the safety magnification factor, generally taking 1 - 1.2, and taking 1.1 in this formula;

[0204] β: is the early warning water level margin, generally taking 1% - 5%. Due to the low aquaculture depth, taking 5% in this formula;

[0205] H1: is the depth of the aquaculture area, m;

[0206] H 1MIN : is the critical minimum value of the aquaculture area water level. In the aquaculture of Litopenaeus vannamei, generally taking 1.5 or 2 / 3 of the aquaculture area water level. Therefore, taking 1.5 in this formula, m;

[0207] V1: is the total volume of the aquaculture area, m 3 .

[0208] Then through calculation, the recommended volume V3 of the water replenishment regulation pool 5 is approximately 3078 m 3 , and the actual volume of the water replenishment regulation pool in the example is approximately 3000 m 3 , and the depth H3 is 2.5 m, which basically meets the conditions.

[0209]

[0210] In the formula:

[0211] Q1: The water pump flow rate of the make-up water pump, m 3 / h;

[0212] V3: The volume of the make-up water regulation tank, m 3 ;

[0213] t1: The make-up water time, which is determined according to the actual situation of the aquaculture area volume. If the value is too small, it is easy to cause stress reactions in Litopenaeus vannamei during make-up water. In this formula, it takes 0.5, h.

[0214] Therefore, the recommended flow rate of the make-up water pump is 1500 m 3 / h. In the embodiment, 4 sewage pumps with a flow rate of 1500 m 3 / h are actually used.

[0215]

[0216] In the formula:

[0217] Q2: The water pump flow rate of the reflux pump, m3 / h;

[0218] H2: The depth of the water outlet area in the water quality improvement area, m;

[0219] β: The early warning water level margin, generally taking 1% - 5%. In this formula, it takes 5%;

[0220] H 2MIN : The water level critical value of the water outlet area in the water quality improvement area, which is determined according to the situation of planting salt-tolerant aquatic plants. Ceratophyllum demersum is suitable for waters with a water depth of 1 - 3 m. Therefore, in this formula, it takes 1, m;

[0221] V2: The volume of the water outlet area in the water quality improvement area, m 3 ;

[0222] t2: The reflux time. In this formula, it takes 0.1, h.

[0223] Therefore, the recommended water pump flow rate of the reflux pump is 5115 m 3 / h. In the embodiment, the actually adopted flow rate is 5200 m 3 / h of sewage pump.

[0224]

[0225] V4: The volume of the water outlet regulation tank, m 3 ;

[0226] α: The safety magnification factor, generally taking 1 - 1.2. In this formula, it takes 1.2;

[0227] β: The early warning water level margin, generally taking 1% - 5%. In this formula, it takes 5%;

[0228] H 2MIN: It is the critical minimum water level of the water outlet area in the water quality improvement area, and the value is taken according to the situation of planting salt-tolerant aquatic plants. In this formula, it is taken as 1, m;

[0229] V2: It is the volume of the water outlet area in the water quality improvement area, m 3 .

[0230] Therefore, the recommended volume of the water outlet regulating tank is about 631.8 m3, and the volume of the water outlet regulating tank in the actual implementation example is about 800 m 3 , and the depth H4 is 2.5 m, which basically meets the requirements.

[0231] Step 2: According to the climate conditions, start the purification process of the system.

[0232] Example 1

[0233] The climate is hot. The numerical control center is set to replenish water twice a day, respectively in the morning and evening, and the time is set at 6:00 and 18:00.

[0234] A. The water body in aquaculture area 1 flows into the tail water purification area 2 for purification;

[0235] B. The numerical control center passes the water at the end of the tail water purification area into the water inlet area (water quality improvement area 1 3-1, water quality improvement area 2 3-2) in the water quality improvement area through the connection valves on the connecting pipes (connecting pipe I 2-1-1, connecting pipe II 2-2-1, connecting pipe III 2-3-1, connecting pipe IV 2-4-1). After passing through the salt-tolerant ecological aquatic plants 3-4, the ultra-micro bubble device 3-5 and by adding microbial agents and filter-feeding salt-tolerant fish 3-6 and other methods, the pollutant concentration is further reduced. It can be adjusted by opening the gate to control the water level.

[0236] C. When the water body flows to the water quality monitoring electric gate 4-10 set at the end of the water quality improvement area 3 (water outlet area), the water quality is judged first. After monitoring, the water quality situation is that the total nitrogen is 2.43 mg / L, the total phosphorus is 0.21 mg / L, and the permanganate index is 4.24 mg / L. The water quality judgment standard is C0. After judgment, it can be obtained that:

[0237] C < C0

[0238] In the formula:

[0239] C: It is the pollutant concentration of the water body at this time, mg / L;

[0240] C0: It is the discharge standard of aquaculture tail water, mg / L.

[0241] D indicates that the water quality meets the standard. Due to the influence of water surface evaporation on the water body in the system, the water level in the system is generally on a downward trend. At this time, the aquaculture area needs to replenish water regularly, so the electric sluice 4-4 is opened, and the purified and up-to-standard water body flows from the third water quality improvement area 3-3 to the water replenishment and regulation pool 5. The water salinity is measured by the water level and salinity monitor 5-7 in the water replenishment and regulation pool 5 to be 1.92%.

[0242] E. The water level of the water replenishment and regulation pool is approaching the critical maximum value H 3MAX It can be determined by the following formula:

[0243]

[0244] In the formula:

[0245] H 3MAX : is the critical maximum value of the water level of the water replenishment and regulation pool, m;

[0246] H3: is the depth of the water replenishment and regulation pool, m;

[0247] β: is the early warning water level margin, generally taking 1% - 5%. In this formula, it takes 5%;

[0248] χ: is the main water quality influencing factor in the water body.

[0249] The main water quality influencing factor χ can be determined by the following formula:

[0250]

[0251] In the formula:

[0252] C: is the concentration of pollutants in the water body at this time, mg / L;

[0253] C0: is the discharge standard of aquaculture tail water, mg / L;

[0254] ρ: is the salinity in the water body at this time, %;

[0255] ρ1: is the set aquaculture salinity in the aquaculture area, %.

[0256] After calculation, the main water quality influencing factor χ in the water body is total nitrogen χ = 0.81. Therefore, the critical maximum value H of the water level of the water replenishment and regulation pool at this time 3MAX is 2.375 m.

[0257] When the numerical control center receives that the water level of the water replenishment and regulation pool is approaching the critical maximum value H 3MAX or the water level of the third water quality improvement area 3-3 drops to H 2MIN , the electric sluice 4-4 is closed at this time. When the numerical control center receives that the water level of the aquaculture area is approaching the critical minimum value H 1MIN、or when the water replenishment regulating pond reaches the preset regular water replenishment time, immediately turn on the groundwater feed pump (feed pump I 5-1, feed pump II 5-2), the water quality regulating salt tank (water quality regulating salt tank I 5-3, water quality regulating salt tank II 5-4, water quality regulating salt tank III 5-5, water quality regulating salt tank IV 5-6) and the air flow stirring device (air flow stirring device I 5-8, air flow stirring device II 5-9). After the water in the pond is adjusted to an appropriate concentration, through the electric sluice (electric sluice 4-5, electric sluice 4-6, electric sluice 4-7, electric sluice 4-8) and the water replenishment pump (aquaculture area I water replenishment pump 1-1-1, aquaculture area II water replenishment pump 1-2-1, aquaculture area III water replenishment pump 1-3-1, aquaculture area IV water replenishment pump 1-4-1), replenish the water into aquaculture area 1 until the water level in aquaculture area 1 reaches the critical maximum value H of the aquaculture area water level 1MAX , and the value is H 1MAX =(1-β)×H1 = 2m.

[0258] Example 2

[0259] The climate is hot, and the numerical control center is set to replenish water twice a day, respectively in the morning and evening, and the time is set to 6:00 and 18:00.

[0260] A. The water in aquaculture area 1 flows into the tail water purification area 2 for purification;

[0261] B. The numerical control center passes the water at the end of the tail water purification area into the water inlet area (3-1, 3-2) of the water quality improvement area through the connecting valve on the connecting pipe (2-1-1, 2-2-1, 2-3-1, 2-4-1). After passing through the salt-tolerant ecological waterweeds (3-4), the ultra-microbubble device (3-5) and by adding microbial agents and filter-feeding salt-tolerant fish (3-6) and other methods, further reduce the pollutant concentration, and the water level can be controlled by opening the gate.

[0262] C. When the water flows to the water quality monitoring electric sluice 4-10 set at the end of the third water quality improvement area (3-3), first conduct water quality judgment. After monitoring, the water quality situation is that the total nitrogen is 6.72 mg / L, the total phosphorus is 0.32 mg / L, and the permanganate index is 12.3 mg / L. The water quality judgment standard is C0. After judgment, it can be obtained that:

[0263] C > C0

[0264] In the formula:

[0265] C: is the pollutant concentration of the water body at this time, mg / L;

[0266] C0: is the aquaculture tail water discharge standard, mg / L.

[0267] D represents that the water quality does not meet the standard. If the return inlet sluice 4-9 is opened, the water body will be conveyed to the front end of the first water quality improvement area 3-1 through the return system 6 for purification again until it meets the standard.

[0268] E. When the water quality in the third water quality improvement area 3-3 does not meet the standard and the water level in the third water quality improvement area 3-3 is on the verge of the critical maximum water level value H 2MAX of the third water quality improvement area 3-3, after the return system 6 works, if the water quality still does not meet the standard, and since the water levels in the water quality improvement area 3 are all at the critical values, the water level in the third water quality improvement area 3-3 is on the verge of the critical maximum water level value H 2MAX of the third water quality improvement area 3-3 again, an alarm will be immediately sent to the numerical control center, and it is necessary to request manual troubleshooting of the reasons.

[0269] At the same time, the water quality monitoring electric sluice 4-10 is opened, and the water body that still does not meet the standard after purification flows from the third water quality improvement area 3-3 to the outlet regulating pond 7, and the following judgment is made:

[0270]

[0271] H 4现状 ≥H 4MAX = H4×(1-β)(χ≤1)

[0272]

[0273] In the formula:

[0274] H 4现状 : is the current water level of the outlet regulating pond, m;

[0275] H 2现状 : is the current water level of the outlet area of the water quality improvement area, m;

[0276] β: is the early warning water level margin, generally taking 1% - 5%, and taking 5% in this formula;

[0277] χ: is the main water quality influencing factor in the water body;

[0278] H 2MAX : is the critical maximum water level of the outlet area of the water quality improvement area, m;

[0279] H 2MIN : is the critical minimum water level of the outlet area of the water quality improvement area, and the value is taken according to the situation of planting salt-tolerant water plants. Taking 1 in this formula, m;

[0280] The main water quality influencing factor χ of this formula can be determined by the following formula:

[0281]

[0282] In the formula:

[0283] C: The concentration of pollutants in the water body at this time, mg / L;

[0284] C0: The discharge standard of aquaculture tail water, mg / L;

[0285] ρ: The salinity in the water body at this time, %;

[0286] ρ0: The salinity of the aquaculture pond tail water where the discharge requirement is located in non-saline-alkali soil areas, taking 1, %.

[0287] According to the monitoring of the water level and salinity meter 7-2, the salinity of this water body is 4.25%, and the calculated main influencing factor is the salinity χ = 4.25.

[0288] When the above judgment formula outputs "truth", the water quality monitoring electric gate 4-10 is closed. Through the water supply pipe 7-1 in the water outlet regulating pond 7, the water level and salinity meter 7-2, and the water quality monitoring electric gate 4-11 installed at the outlet of the water outlet regulating pond 7, through the coordinated cooperation of the monitoring data of the three, after diluting the water body to an appropriate concentration, the water quality monitoring electric gate 4-11 is opened, and the tail water is discharged into the river.

[0289] F. During subsequent manual inspections, it was found that due to the death of some hornworts in the third area of water quality improvement under direct sunlight and their decay in the water, the water quality did not meet the standards.

[0290] Example 3

[0291] When heavy rain suddenly drops and the water level soars, the numerical control center activates the rainstorm warning system, the water replenishment regulating pond 5 is closed, and the appropriate amount of aerators installed at the bottom in the aquaculture area 1 are turned on.

[0292] A. The appropriate amount of aerators installed at the bottom in the aquaculture area 1 are turned on, and part of the water body in the aquaculture area 1 flows into the tail water purification area 2 for purification.

[0293] B. Due to the large flow rate, most of the water flow will enter the water inlet areas (the first area of water quality improvement 3-1 and the second area of water quality improvement 3-2) of the water quality improvement area through the overflow method. The flow rate in the water quality improvement area is large, and at this time, the water level can be controlled by opening the gate for adjustment. The numerical control center in the tail water purification area passes the water at the end of the tail water purification area into the water inlet area of the water quality improvement area through the connection valve on the connecting pipe. After passing through the salt-tolerant ecological waterweeds 3-4, the ultra-microbubble device 3-5, and by adding microbial agents and filter-feeding salt-tolerant fish 3-6 and other methods, the pollutant concentration is further reduced, and the water level can be controlled by opening the gate for adjustment.

[0294] When the water body flows to the water quality monitoring electric gate 4-10 at the end of the third water quality improvement area 3-3 for water quality improvement, the water quality is first judged. After monitoring, the water quality conditions are: total nitrogen 1.2 mg / L, total phosphorus 0.06 mg / L, and permanganate index 2.34 mg / L. The water quality judgment standard is C0. After judgment, it can be obtained that:

[0295] C < C0

[0296] In the formula:

[0297] C: is the concentration of pollutants in the water body at this time, mg / L;

[0298] C0: is the discharge standard of aquaculture tail water, mg / L.

[0299] D. It represents that the water quality meets the standard. Since there is sufficient water source in the system and no water replenishment is required, the water quality monitoring electric gate 4-10 and the water quality monitoring electric gate 4-11 are opened, and an appropriate amount of water body is discharged until the water quality does not meet the standard, or The water quality monitoring electric gate 4-10 and the water quality monitoring electric gate 4-11 are closed again.

[0300] Example 4

[0301] When heavy rain suddenly drops and the water level rises sharply, the numerical control center activates the rainstorm warning system, the water replenishment regulating pond 5 is closed, and an appropriate amount of aerators installed at the bottom of the aquaculture area 1 are turned on.

[0302] A. An appropriate amount of aerators installed at the bottom of the aquaculture area 1 are turned on, and a part of the water body in the aquaculture area 1 flows into the tail water purification area 2 for purification;

[0303] B. Due to the large flow rate, most of the water flow will enter the water inlet areas (the first water quality improvement area 3-1, the second water quality improvement area 3-2) of the water quality improvement area through the overflow method. The flow rate in the water quality improvement area is large. At this time, the water level can be controlled by opening the gate. The numerical control center of the water body in the tail water purification area passes the water at the end of the tail water purification area into the water inlet areas (the first water quality improvement area 3-1, the second water quality improvement area 3-2) of the water quality improvement area through the connecting valves on the connecting pipes (connecting pipe I 2-1-1, connecting pipe II 2-2-1, connecting pipe III 2-3-1, connecting pipe IV 2-4-1). After passing through the salt-tolerant ecological waterweeds 3-4 and the ultra-microbubble device 3-5, and by adding microbial agents and filter-feeding salt-tolerant fish 3-6 and other methods, the pollutant concentration is further reduced, and the water level can be controlled by opening the gate.

[0304] C. When the water body flows to the water quality monitoring electric gate 4-10 at the end of the third water quality improvement area 3-3, the water quality is first judged. After monitoring, the water quality conditions are: total nitrogen 5.43 mg / L, total phosphorus 0.45 mg / L, and permanganate index 16.2 mg / L. The water quality judgment standard is C0. After judgment, it can be obtained that:

[0305] C > C0

[0306] Where:

[0307] C: is the concentration of pollutants in the water body at this time, mg / L;

[0308] C0: is the discharge standard of aquaculture tail water, mg / L.

[0309] D. If it represents that the water quality does not meet the standard, the water body will be transported to the front end of the first water quality improvement area 3-1 through the reflux system 6 for further purification until it meets the standard.

[0310] E. After the above step D, if the water quality still does not meet the standard, and since the water levels in the water quality improvement area 3 are all at the critical water level, the water level in the third water quality improvement area 3-3 is on the verge of the critical maximum value H of the water level in the third water quality improvement area 3-3 2MAX at this time, an alarm will be immediately sent to the numerical control center, and it is necessary to request manual investigation of the reasons.

[0311] At the same time, the water quality monitoring electric gate 4-10 is opened, and the water body that still does not meet the standard after purification flows from the third water quality improvement area 3-3 to the outlet regulating pond 7, and the following judgment is made:

[0312]

[0313] H 4现状 ≥H 4MAX = H4×(1 - β)(χ0 ≤ 1)

[0314]

[0315] Where:

[0316] H 4现状 : is the current water level of the outlet regulating pond, m;

[0317] H 2现状 : is the current water level of the water outlet area of the water quality improvement area, m;

[0318] β: is the early warning water level margin, generally taking 1% - 5%, and taking 5% in this formula;

[0319] χ0: is the main water quality influencing factor in the discharged water body;

[0320] H 2MAX : is the critical maximum value of the water level in the water outlet area of the water quality improvement area, m;

[0321] H 2MIN : is the critical minimum value of the water level in the water outlet area of the water quality improvement area, which is determined according to the situation of planting salt-tolerant water plants, m;

[0322] The main water quality influencing factor χ0 of this formula can be determined by the following formula:

[0323]

[0324] In the formula:

[0325] C: is the concentration of pollutants in the water body at this time, mg / L;

[0326] C0: is the discharge standard of aquaculture tail water, mg / L;

[0327] ρ: is the salinity in the water body at this time, %;

[0328] ρ0: is the salinity of the aquaculture pond tail water where the discharge requirement is located in non-saline-alkali soil areas, taking 1, %.

[0329] According to the monitoring of the water level and salinity meter 7-2, the salinity of this water body is 0.97%, and the calculated main influencing factor is total nitrogen χ = 1.81.

[0330] When the output is truth, the water quality monitoring electric gate 4-10 is closed. Through the water supply pipe 7-1 in the water outlet regulation pond 7, the water level and salinity meter 7-2, and the water quality monitoring electric gate 4-11 installed at the outlet of the water outlet regulation pond 7, through the coordinated cooperation of the monitoring data of the three, after diluting the water body to an appropriate concentration, the water quality monitoring electric gate 4-11 is opened, and the tail water is discharged into the river.

[0331] F. According to the subsequent manual investigation of the reasons, it is found that due to the damage of some slopes in the third area of water quality improvement, rainwater seeps into the ground and mixes with a small amount of sediment from the damaged slopes, resulting in unqualified water quality. The situation has improved after emergency manual reinforcement.

Claims

1. A multi-stage circulating ecological purification system for aquaculture tail water based on salinity regulation, characterized in that: The system includes a farming area (1), a tail water purification area (2), a water quality improvement area (3), an electric sluice module (4), a make-up water regulation pond (5), a reflux system (6) and an effluent regulation pond (7). Electric sluices and water level and salinity meters are provided between or within these areas, which are connected to a numerical control center to transmit the detected real-time data to the numerical control center, and the numerical control center controls the operation of each system; The tail water purification area (2) is separated from the farming area (1) by a ridge. A connecting pipe with a connecting valve is provided in the ridge for introducing the sewage in the farming area (1) into the tail water purification area (2) to establish a hydraulic connection between the areas; The output end of the tail water purification area (2) is connected to the water quality improvement area, which is used to receive and secondary purify the tail water and simultaneously perform subsequent diversion treatment; the output end of the water quality improvement area (3) is connected to the make-up water regulation pond (5) and the effluent regulation pond (7) at the same time. According to the load condition of the system, the system controls the direction of the purified effluent; The make-up water regulation pond (5) is connected to the farming area (1) through a pipe with an electric sluice and a make-up water pump, which is used to transport the purified water body in the make-up water regulation pond (5) to the farming area when needed; A water level and salinity meter (7-2) is provided inside the effluent regulation pond (7), and a water quality monitoring electric sluice II (4-11) is provided at the outlet. After diluting the tail water to the standard concentration through a water pipe, it is discharged into the river; The reflux system is connected to the water quality improvement area (3) through a reflux pipe with a reflux pump, which is used to pump the unqualified tail water to the water quality improvement area (3) for re-purification to form a cyclic purification system.

2. The multi-stage circulating ecological purification system for aquaculture tail water based on salt content regulation according to claim 1, characterized in that: The said farming area (1) is divided into more than one farming block, and each farming block is provided with a corresponding tail water purification block for the primary purification of farming tail water. The farming blocks and the tail water purification blocks are separated by ridges, and a connecting pipe is provided in the middle of the ridge for introducing the farming block into the tail water purification block to establish a hydraulic connection within the block.

3. The multi-stage circulating ecological purification system for aquaculture tail water based on salt regulation according to claim 2, characterized in that: At most two farming blocks are connected to one tail water purification area. Filter-feeding salt-tolerant fish are put in the tail water purification area, and the pollutant concentration in the farming tail water is reduced by the gill rakers of the filter-feeding salt-tolerant fish.

4. The multi-stage circulating ecological purification system for aquaculture tail water based on salt content regulation according to claim 2, characterized in that: A water level and salinity monitor is provided in each farming block for monitoring the water level and water body salinity content in the farming area (1). At the same time, an aerator should be installed at the bottom of each farming block for uniformly mixing the water body in the farming area and increasing the dissolved oxygen content in the water body in the farming area.

5. The multi-stage circulating ecological purification system for aquaculture tail water based on salt content regulation according to claim 1, wherein: The water quality improvement area is divided into three parts. The first two are water inlet areas, namely the water quality improvement area III-1 (3-1) and the water quality improvement area III-2 (3-2) in sequence. The last part is the water outlet area, namely the water quality improvement area III-3 (3-3). The three are arranged alternately in sequence, and a water quality monitoring electric sluice I (4-10) is set at the end of the water outlet area.

6. The multi-stage circulating ecological purification system for aquaculture tail water based on salt regulation according to claim 5, wherein: Salt-tolerant ecological waterweeds (3-4) are planted at the bottom of the water quality improvement area (3), an ultramicrobubble device (3-5) is installed at the bottom, and filter-feeding salt-tolerant fish are put in the water body to reduce the pollutant concentration through their synergistic effects.

7. The multi-stage circulating ecological purification system for aquaculture tail water based on salt regulation according to claim 5, wherein: The electric sluice module (4) includes the electric sluices set between the various areas in the water quality improvement area, the water quality monitoring electric sluice I (4 - 10) at the end of the water outlet area of the water quality improvement area, and the return water outlet electric sluice set at the end of the return system (6); the electric sluice set between the make-up water regulation pond (5) and the aquaculture area, and the water quality monitoring electric sluice II (4 - 11) at the end of the water outlet regulation pond, which is used to control the discharge of tail water into the river.

8. The multi-stage circulating ecological purification system for aquaculture tail water based on salt regulation according to claim 5, characterized in that: In the make-up water regulation pond (5), a water quality regulation salt tank and a water level and salinity monitor (5 - 7) are arranged. Suitable salts for the growth of Litopenaeus vannamei are stored in the salt tank, and the numerical control center regulates the salt dosage to adjust the salinity of the water body in the make-up water regulation pond (5); the water level and salinity monitor monitors the water level and salinity of the water body; an air-flow type stirring device is installed in the make-up water regulation pond (5).

9. The operation process of a multi-stage circulating ecological purification system for aquaculture tail water based on salt content regulation according to any one of claims 1 to 8, characterized in that, The steps are as follows: (1) The tail water in the aquaculture area passes through the purification area, and the filter-feeding salt-tolerant fish are used to purify the tail water in the aquaculture area for the first time. (2) The purified tail water passes through the salt-tolerant ecological waterweeds, ultra-microbubble devices, microbial agents, and filter-feeding salt-tolerant fish in the water inlet area of the water quality improvement area to purify the tail water for the second time. (3) The purified tail water is detected by the water quality monitoring electric sluice I (4 - 10) in the water outlet area of the water quality improvement area. If the water quality does not meet the standard, the return system is opened to purify the water body again; if the water quality meets the standard, it is judged by the numerical control center. If the system needs to make up water, the water body is sent to the make-up water regulation pond, and after adjusting the salinity, it is transported to the aquaculture area; if the system is threatened by a sharp rise in water level, the water body is sent to the water outlet regulation pond, and after diluting the water body concentration, it is discharged into the river.

10. The operation process of a multi-stage circulating ecological purification system for aquaculture tail water based on salt regulation according to claim 9, characterized in that, The specific steps are as follows: The first step: Estimate the total volume V1 and the depth H1 of the aquaculture area (1) after completion, as well as the volume V2 and depth H2 of the water outlet area of the water quality improvement area, and calculate and determine the following supporting facility parameters; The volume V3 of the make-up water regulation pond (5), the pump flow rate Q1 of the make-up water pump, the pump flow rate Q2 of the return pump, and the volume V4 of the water outlet regulation pond; In the formula: V3: Volume of the water replenishment regulating pond, m 3 ; α: is the safety amplification factor, taking 1 - 1.2; β: is the early warning water level margin, taking 1% - 5%; H1: is the depth of the aquaculture area, m; H 1MIN : The critical minimum water level of the aquaculture area, which is taken as 1.5 m or 2 / 3 of the water level of the aquaculture area in the cultivation of white - leg shrimp, m; V1: Total volume of the aquaculture area, m 3 ; In the formula: Q1: The water pump flow rate of the make-up water pump, m 3 / h; V3: The volume of the water replenishment regulating tank, m 3 ; t1: is the make-up water time, which is determined according to the actual situation of the aquaculture area volume. If the value is too small, it is easy to cause stress reactions in Litopenaeus vannamei during make-up water, h; In the formula: Q2: is the pump flow rate of the return pump, m3 / h; H2: is the depth of the water outlet area of the water quality improvement area, m; β: is the early warning water level margin, taking 1% - 5%; H 2MIN : The water level critical value of the effluent area in the water quality improvement area, which is determined according to the situation of planting salt-tolerant aquatic plants, m; V2: Volume of the effluent area in the water quality improvement area, m 3 ; t2: is the return time, h; V4: Volume of the effluent regulating tank, m 3 ; α: is the safety amplification factor, taking 1 - 1.2; β: is the early warning water level margin, taking 1% - 5%; H 2MIN : The critical minimum water level of the effluent area in the water quality improvement area, which is determined according to the situation of planting salt-tolerant aquatic plants, m; V2: Volume of the effluent area in the water quality improvement area, m 3 ; The second step: According to the climate conditions, start the purification process of the system (1) In hot and dry climate or humid climate with little rainfall, the characteristics of the tail water at this time are small water flow and high pollutant concentration, and the numerical control center normally takes corresponding measures according to the climate characteristics; A. The water body in the aquaculture area (1) flows into the tail water purification area (2) for purification; B. The CNC center passes the water at the end of the tail water purification area into the water quality improvement area by adjusting the connecting valve on the connecting pipe. After passing through the salt-tolerant ecological waterweeds and the ultramicrobubble equipment (and further reducing the pollutant concentration by adding microbial agents and filter-feeding salt-tolerant fish, the water level is controlled by adjusting the gate; C. When the water body flows to the water quality monitoring electric gate I (4 - 10) set at the end of the third water quality improvement area (3 - 3), the water quality is judged first. The water quality judgment standard is C0: C > C0 In the formula: C: is the pollutant concentration of the water body at this time, mg / L; C0: is the discharge standard of aquaculture tail water, mg / L; The discharge standard C0 of aquaculture tail water includes the discharge concentration standards of various pollutants. As long as one of the pollutant concentrations C of the water body satisfies the above formula C > C0, the output of this formula is truth, otherwise the output is false; D. If the output is truth, it means that the water quality does not meet the standard. Then the water body is transported to the front end of the first water quality improvement area (3 - 1) again for purification through the reflux system (6) until it meets the standard; E. If the output is false, it means that the water quality meets the standard. Due to the influence of water surface evaporation on the water body in the system, the water level in the system is generally in a downward trend. At this time, the aquaculture area needs to replenish water regularly. Then the electric gate is opened, and the purified and up-to-standard water body flows from the third water quality improvement area (3 - 3) to the water replenishment regulation pool (5); F. The water level of the make-up regulation pond is approaching the critical maximum value H 3MAX which is determined by the following formula: In the formula: H 3MAX : water level of the make-up regulation pond approaching the critical maximum value, m; H3: is the depth of the water replenishment regulation pool, m; β: is the early warning water level margin, taking 1% - 5%; χ: is the main water quality influencing factor in the water body; The main water quality influencing factor χ is determined by the following formula: In the formula: C: is the pollutant concentration of the water body at this time, mg / L; C0: is the discharge standard of aquaculture tail water, mg / L; ρ: is the salinity in the water body at this time, %; ρ1: is the set aquaculture salinity in the aquaculture area, %; When the numerical control center receives that the water level of the water replenishment regulation pool is approaching the critical maximum value H 3MAX or the water level of the third area (3-3) for water quality improvement drops to H 2MIN , at this time, the electric gate is closed. When the numerical control center receives that the water level of the aquaculture area is approaching the critical minimum value H 1MIN , or the water replenishment regulation pool reaches the preset regular water replenishment time, immediately turn on the groundwater feed pump, the water quality regulation salt tank and the air-flow stirring device. After the water body in the pool is adjusted in concentration, the water body is replenished into the aquaculture area (1) through the electric gate and the water replenishment pump until the water level in the aquaculture area (1) reaches the critical maximum value H of the water level in the aquaculture area 1MAX , value: H 1MAX = (1 - β) × H1; G. If the water quality in the third water quality improvement zone (3-3) meets the standard, and the make-up water regulation tank is working or the water level has reached the critical maximum value H of the make-up water regulation tank 3MAX At this time, if the water level in the third water quality improvement zone (3-3) is approaching the critical maximum value H of the water level in the third water quality improvement zone (3-3) 2MAX At this time, that is: H 2现状 = H 2MAX = (1 - β) × H2 Then there is no lack of water in the system, and even the water source is sufficient; the water quality monitoring electric gate I (4 - 10) is opened, and the purified and up-to-standard water body flows from the third water quality improvement area (3 - 3) to the water outlet regulation pool (7), and the following judgment is made: In the formula: H 4现状 : Current water level of the water outlet regulating pond, m; H 2现状 : The current water level of the effluent area in the water quality improvement area, m; β: is the early warning water level margin, taking 1% - 5%; χ0: is the main water quality influencing factor in the discharged water body; H 2MAX : The critical maximum water level of the effluent area in the water quality improvement area, m; H 2MIN : The critical minimum water level of the effluent area in the water quality improvement area, which is determined according to the situation of planting salt-tolerant aquatic plants, m; The main water quality influencing factor χ0 of this formula is determined by the following formula: In the formula: C: is the pollutant concentration of the water body at this time, mg / L; C0: is the discharge standard of aquaculture tail water, mg / L; ρ: is the salinity in the water body at this time, %; ρ0: is the salinity of the aquaculture pond tail water required for discharge in non-saline-alkali soil areas, taking 1, %; H. If the judgment output is truth, then close the water quality monitoring electric gate I (4 - 10). Through the water supply pipe, the water level and salinity meter in the water outlet regulation pool (7), and the water quality monitoring electric gate II (4 - 11) at the outlet of the water outlet regulation pool (7), through the coordinated cooperation of the monitoring data of the three, dilute the water body to the up-to-standard concentration, then open the water quality monitoring electric gate II (4 - 11), and discharge the tail water into the river; Emergency Situation I: When the water quality in the third water quality improvement zone (3-3) does not meet the standard, and the water level in the third water quality improvement zone (3-3) is on the verge of the critical maximum water level H of the third water quality improvement zone (3-3) 2MAX When the water quality still does not meet the standard after the operation of the return system (6), and since the water levels in the water quality improvement zone (3) are all at the critical values, the water level in the third water quality improvement zone (3-3) is again on the verge of the critical maximum water level H of the third water quality improvement zone (3-3) 2MAX Immediately send an alarm to the numerical control center and request manual investigation of the cause; At the same time, the water quality monitoring electric gate I (4 - 10) is opened, and the still unqualified water body after purification flows from the third water quality improvement area (3 - 3) to the water outlet regulation pool (7), and the following judgment is made: H 4现状 ≥H 4MAX =H4×(1-β)(χ0≤1) In the formula: H 4现状 : Current water level of the effluent regulating pond, m; H 2现状 : The current water level of the effluent area in the water quality improvement area, m; β: is the early warning water level margin, taking 1% - 5%; χ0: The main water quality influencing factor in the discharged water body; H 2MAX : The critical maximum water level of the effluent area in the water quality improvement area, m; H 2MIN : The critical minimum water level of the effluent area in the water quality improvement area, which is determined according to the situation of planting salt-tolerant aquatic plants, m; The main water quality influencing factor χ0 of this formula is determined by the following formula: In the formula: C: The concentration of pollutants in the water body at this time, mg / L; C0: The discharge standard of aquaculture tail water, mg / L; ρ: The salinity in the water body at this time, %; ρ0: The salinity of the aquaculture pond tail water where the discharge requirement is located in non-saline-alkali soil area, taking 1, %; When the output is truth, close the water quality monitoring electric gate Ⅰ (4 - 10), and through the water supply pipe, water level salinity meter in the effluent regulating pond (7) and the water quality monitoring electric gate Ⅱ (4 - 11) at the outlet of the effluent regulating pond, through the coordinated cooperation of the monitoring data of the three, dilute the water body to the standard concentration, then open the water quality monitoring electric gate Ⅱ (4 - 11), and discharge the tail water into the river; (2) When there is a sudden heavy rain and the water level rises sharply, the characteristic of the tail water at this time is large water flow and small pollutant concentration. The numerical control center adopts a rainstorm warning system according to the climate characteristics; A. Turn on the aerator installed at the bottom in the aquaculture area (1), and part of the water body in the aquaculture area (1) flows into the tail water purification area (2) for purification; B. Due to the large flow, most of the water will enter the water inlet area of the water quality improvement area through the way of overflow; the flow in the water quality improvement area is large, and the water level is controlled by the gate adjustment; the numerical control center adjusts the connecting valve on the connecting pipe to let the water at the end of the tail water purification area flow into the water inlet area of the water quality improvement area, and further reduces the pollutant concentration through salt-tolerant ecological waterweeds, ultrafine bubble equipment and by adding microbial agents and filter-feeding salt-tolerant fish, and controls the water level by the gate adjustment; C. When the water body flows to the water quality monitoring electric gate Ⅰ (4 - 10) set at the end of the water quality improvement area three (3 - 3), first conduct water quality judgment, and the water quality judgment standard is C0: C > C0 In the formula: C: The concentration of pollutants in the water body at this time, mg / L; C0: The discharge standard of aquaculture tail water, mg / L; The aquaculture tail water discharge standard C0 includes the discharge concentration standards of various pollutants. As long as one of the pollutant concentrations C in the water body satisfies the above formula C > C0, the output of this formula is truth, otherwise the output is false; D. If the output is truth, it means that the water quality does not meet the standard, then the water body is transported to the front end of the water quality improvement area one (3 - 1) again for purification through the reflux system (6) until it meets the standard; Emergency situation E: If, after the above step D, the water quality still does not meet the standard, and since the water levels in the water quality improvement area (3) are all at the water level critical value, the water level in the third water quality improvement area (3-3) is on the verge of reaching the critical maximum value H of the water level in the third water quality improvement area (3-3) again 2MAX Immediately send an alarm to the numerical control center and request manual investigation of the cause; At the same time, the water quality monitoring electric gate Ⅰ (4 - 10) is opened, and the water body that still does not meet the standard after purification flows from the water quality improvement area three (3 - 3) to the effluent regulating pond (7), and the following judgment is made: H 4现状 ≥H 4MAX = H4×(1-β)(χ0≤1) In the formula: H 4现状 : Current water level of the water outlet regulating pond, m; H 2现状 : The current water level of the effluent area in the water quality improvement area, m; β: The early warning water level margin, taking 1% - 5%; χ0: The main water quality influencing factor in the discharged water body; H 2MAX : The critical maximum water level of the effluent area in the water quality improvement area, m; H 2MIN : The critical minimum water level of the effluent area in the water quality improvement area, which is determined according to the situation of planting salt-tolerant aquatic plants, m; The main water quality influencing factor χ0 of this formula is determined by the following formula: In the formula: C: The concentration of pollutants in the water body at this time, mg / L; C0: The discharge standard of aquaculture tail water, mg / L; ρ: The salinity in the water body at this time, %; ρ0: The salinity of the aquaculture pond tail water where the discharge requirement is located in non-saline-alkali soil area, taking 1, %; When the output is "truth", close the water quality monitoring electric valve Ⅰ (4-10). Through the water supply pipe, water level and salinity meter in the effluent regulating tank (7), and the water quality monitoring electric valve Ⅱ (4-11) installed at the outlet of the effluent regulating tank, through the coordinated cooperation of the monitoring data of the three, dilute the water body to the standard concentration, then open the water quality monitoring electric valve Ⅱ (4-11) and discharge the tail water into the river; F. If the water quality in the water quality improvement area three (3-3) is judged and the output is false, it means that the water quality meets the standard. Since there is sufficient water source in the system and no water replenishment is required, open the water quality monitoring electric valve I (4-10) and discharge the water until the water quality does not meet the standard, or close the water quality monitoring electric valve I (4-10) again.

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