Farmland saline-alkali water deployment recycling system

Abstract

The application provides a farmland saline-alkali water deployment recycling system and relates to the technical field of saline-alkali water recycling, which comprises a water collecting well, a dry pipe connected above the outer side of the water collecting well, branch pipes fixedly connected to the two sides of the dry pipe, and blocking cotton covers fixedly arranged above the branch pipes; a water precipitation well, a sealing cover fixedly arranged at the top of the water precipitation well, and a water pump fixedly connected to the top of the water precipitation well and the top of the water collecting well; through water recovery of saline-alkali land, water can be stored and deployed as needed; water in a drainage ditch is input into a water purification device, and purified water flows into a water purification tank; a one-way water pump is opened to extract pure water in proportion, which is mixed with saline-alkali water, and a spiral propeller is used for auxiliary conveying and stirring, so that the mixed water can be input into a water storage tank; finally, an output pipeline arranged in the water storage tank is connected to irrigation equipment to realize irrigation, thereby solving the problem that existing irrigation facilities are inconvenient to deploy saline-alkali water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of saline water reuse, in particular to a farmland saline water deployment reuse system. BACKGROUND

[0002] The total area of saline land in China is about 99 million hectares, most of which is distributed in the northwest region of China. This region is an important grain production base in China, but it is facing the problem of drought and water shortage. If saline water can be reused, it will be conducive to ensuring China's food security.

[0003] Crops have different tolerances to salinity at different growth stages. Therefore, adjusting the salinity of irrigation water according to the growth stage of crops and improving the use rate of saline water can effectively reduce irrigation costs. However, the current irrigation facilities cannot adjust and configure according to the salinity, and cannot reasonably apply and process saline water. High salinity can cause crop death, and low salinity is not economical. SUMMARY

[0004] Therefore, the present application provides a farmland saline water deployment reuse system, which has a screw propeller that can assist in conveying and stirring water bodies of different salinities. The water can be fully mixed and then input into a water storage tank. Finally, the water in the water storage tank can be connected to irrigation equipment through an output pipeline for irrigation, realizing the deployment and reuse of saline water.

[0005] The present application provides a farmland saline water deployment reuse system, which specifically comprises: a water collection well, a dry pipe is connected above the outer side of the water collection well, branch pipes are fixedly connected on both sides of the dry pipe, and a blocking cotton cover is fixedly arranged above the branch pipes; a precipitation well, a sealing cover is fixedly arranged on the top of the precipitation well, a water pump is fixedly connected to the top of the precipitation well and the top of the water collection well, a suction pipe connected to the inside of the water collection well and the precipitation well is arranged at the input end of the water pump; a water storage tank, an input device is fixedly arranged on the lower side of one side of the water storage tank, a pipeline connected to the top of the input device is arranged at the top of the water pump, and a clean water tank is further arranged in the pipeline; an electric conductivity sensor is arranged in the water collection well, the precipitation well and the water storage tank.

[0006] A water purification device comprises a drainage tank, a source water pump, a first bag filter, a second bag filter, a multi-medium filter, a water inlet valve, a security filter and a high-pressure pump which are sequentially connected through pipelines; the high-pressure pump is connected to a reverse osmosis device, and the reverse osmosis device is connected with a pure water tank; a drainage ditch is further arranged outside the water collection well and connected through a pipeline, and the drainage ditch is connected to the drainage tank through a pipeline; the top of the clean water tank is connected to the water outlet end of the pure water tank through a pipeline; and a one-way water pump is arranged at the outlet of the clean water tank.

[0007] Optionally, the pipeline of the water collection well and the drainage ditch is lower than the dry pipe, so as to ensure the flow direction; an exhaust valve pipe is fixedly arranged on the top of the precipitation well, the water storage tank and the clean water tank.

[0008] Optionally, the inside of the input device is sealed and rotatably provided with a screw propeller driven by a motor.

[0009] Optionally, an electromagnetic valve A is connected at the outlet of the one-way water pump.

[0010] Optionally, the input end of the input device is further connected with an electromagnetic valve B.

[0011] Optionally, side positioning grooves are formed on both sides of the exhaust valve pipe and are fixed by bolt locking structures; the bottom of the exhaust valve pipe is a flange structure, a sliding rod is fixedly arranged at the bottom of the exhaust valve pipe, a floating valve is slidably arranged outside the sliding rod, and a baffle is fixedly arranged at the bottom of the sliding rod; a plug-in top cover is clamped at the top of the exhaust valve pipe.

[0012] Optionally, the water purification device further comprises an input device connected between the security filter and the high-pressure pump, for delivering sterilizing agent and scale inhibitor to the water purification device; a impeller group is rotatably arranged inside the input device in cooperation with a sealing bearing; the main body of the input device is an eccentric channel, side transmission frames are fixedly arranged on both sides of the input device, and crankshafts are rotatably arranged in the middle of the input device; electric cylinders are fixedly arranged at the bottom of the side transmission frames, sliding turrets are fixedly arranged at the extension ends of the electric cylinders, and linkage gears are rotatably arranged in the sliding turrets.

[0013] Optionally, guide sliding rods are fixedly arranged on the upper and lower ends of both sides of the input device, and strip frames are slidably arranged between the two groups of guide sliding rods on the same side; combination gears are fixedly arranged outside the shaft ends of the impeller group and the crankshafts; the linkage gears can engage with the two groups of combination gears when the electric cylinders are extended; delivery pistons are fixedly arranged on both sides of the input device, the extension ends of the delivery pistons are fixedly connected with the strip frames; one-way valves A and one-way valves B are connected to the tail ends of the delivery pistons, and the one-way valves A are connected to the inside of the input device; the two one-way valves B are respectively connected with the sterilizing agent and the scale inhibitor.

[0014] The beneficial effects are as follows:

[0015] 1. By recycling water from saline-alkali soil, water can be stored and adjusted as needed, and ditch water can be input into the water purification device, and purified water can flow into the water purification tank; opening the one-way water pump can extract pure water in proportion, mix it with saline-alkali water, and use the screw propeller to assist in conveying and stirring, so that the mixed water can be input into the water storage tank, and finally the output pipeline connected to the irrigation equipment in the water storage tank can be used for irrigation, realizing the utilization of saline-alkali water.

[0016] 2, set exhaust valve pipe, can provide air conditioning function, when the water level of precipitation well, water storage tank and water tank is raised, air can pass through the middle of exhaust valve pipe and discharge, when the water level is too high, it will float the float valve and block the exhaust valve pipe to avoid the water level to continue to increase and discharge, and the plug-in top cover can block the outside to provide protection, easy to assemble, can automatically adjust breath and control opening and closing.

[0017] 3, set input, provides driving input function, when water passes through the input, it drives the impeller group to rotate; start the electric cylinder to move the sliding turntable, engage the linkage gear with the combination gear, can drive the crankshaft and the impeller group, the crankshaft drives the strip frame to move back and forth, repeatedly extruding the delivery piston, through the variable volume, using the check valve B to suck the bactericide or scale inhibitor, then it passes through the check valve A into the outlet of the input, realizes automatic addition, and can adjust the input type of bactericide and scale inhibitor according to the need, and can adjust the input ratio by controlling the transmission time. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The overall arrangement structure schematic diagram of the embodiment in the application is shown;

[0019] Figure 2 The three-dimensional structure schematic diagram of the input of the embodiment in the application is shown;

[0020] Figure 3 The axonometric structure schematic diagram of the input of the embodiment in the application is shown;

[0021] Figure 4 The three-dimensional sectional structure schematic diagram of the input of the embodiment in the application is shown;

[0022] Figure 5 The three-dimensional disassembly structure schematic diagram of the exhaust valve pipe of the embodiment in the application is shown;

[0023] Figure 6 The side elevation disassembly structure schematic diagram of the exhaust valve pipe of the embodiment in the application is shown;

[0024] Figure 7 The A local enlarged structure schematic diagram of the embodiment in the application is shown;

[0025] Figure 8 The deployment system flow structure schematic diagram of the embodiment in the application is shown;

[0026] Figure 9 The water purification equipment structure schematic diagram of the embodiment in the application is shown;

[0027] Figure 10 The style schematic diagram of the gravel filter box of the embodiment in the application is shown.

[0028] LIST OF REFERENCE NUMERALS

[0029] 1, water collection well; 2, main pipe; 3, branch pipe; 301, blocking cotton cover; 4, dewatering well; 5, water pumping pump; 6, drainage ditch; 7, water storage tank; 701, input device; 702, screw propeller; 8, clean water tank; 801, one-way water pump; 9, electromagnetic valve A; 10, electromagnetic valve B; 11, exhaust valve pipe; 1101, side positioning groove; 1102, sliding rod; 1103, floating valve; 1104, plug-in top cover; 12, water purification equipment; 1201, drainage tank; 1202, source water pump; 1203, first-stage bag filter; 1204, second-stage bag filter; 1205, multi-medium filter; 1206, water inlet valve; 1207, security filter; 1208, high-pressure pump; 1209, reverse osmosis device; 1210, pure water tank; 1211, chemical washing valve; 1212, chemical washing pump; 1213, chemical washing tank; 13, inputter; 1301, impeller group; 1302, side transmission frame; 1303, crankshaft; 1304, electric cylinder; 1305, sliding trolley; 1306, linkage gear; 1307, guide sliding rod; 1308, strip frame; 1309, combined gear; 1310, delivery piston; 1311, one-way valve A; 1312, one-way valve B. DETAILED DESCRIPTION

[0030] In order to make the purpose, scheme and advantages of the technical scheme of the present application more clear, the technical scheme of the present application embodiment will be described clearly and completely in combination with the drawings of the specific embodiments of the present application below.

[0031] Embodiment 1:

[0032] Please refer to the drawings in the specification, Figures 1 to 10 as shown:

[0033] This invention proposes a system for the reprocessing and reuse of saline-alkali water in farmland, comprising: a collection well 1, with a main pipe 2 connected to the upper outer side of the collection well 1, and branch pipes 3 fixedly connected to both sides of the main pipe 2. Each branch pipe 3 is covered with a barrier cotton cover 301, primarily for filtration to prevent pipe blockage; the filter material can be geotextile-wrapped. A dewatering well 4, with a sealing cap fixedly installed on its top. A water pump 5 is fixedly connected to the top of both the dewatering well 4 and the collection well 1. The input end of the water pump 5 has a suction pipe connected to the lower interior of both the collection well 1 and the dewatering well 4. A water storage tank 7, with an input device 701 fixedly installed on one side of the lower part of the storage tank 7. The input end of the input device 701 is also connected to a solenoid valve B10. The internal sealed rotating device is equipped with a motor-driven screw propeller 702 to fully mix the water. The top of the water pump 5 is connected to the top of the input device 701 via a pipe. A branch of the pipe is also connected to the water purification tank 8. A one-way water pump 801 is connected to the outlet of the water purification tank 8, and a solenoid valve A9 is connected to the outlet of the one-way water pump 801. The tops of the dewatering well 4, the water storage tank 7, and the water purification tank 8 are all fixedly equipped with vent valve pipes 11. Conductivity sensors are installed inside the water collection well 1, the dewatering well 4, and the water storage tank 7. A pipe is also connected to the drainage ditch 6 outside the water collection well 1. The pipe between the water collection well 1 and the drainage ditch 6 is lower than the main pipe 2. This arrangement can ensure the flow direction. When the water level in the water collection well 1 is too high, it will flow into the drainage ditch 6 and be discharged.

[0034] Water purification equipment 12 includes a diversion tank 1201, a source water pump 1202, a primary bag filter 1203, a secondary bag filter 1204, a multi-media filter 1205, an inlet valve 1206, a security filter 1207, and a high-pressure pump 1208, all connected sequentially by pipes. The high-pressure pump 1208 is connected to a reverse osmosis unit 1209, which is connected to a pure water tank 1210. A pipe is installed at the top of the purified water tank 8 to connect to the pure water tank 1210. At the outlet of 10, one side of the pure water tank 1210 is connected to the chemical washing tank 1213. A chemical washing pump 1212 and a chemical washing valve 1211 are sequentially installed at the rear of the chemical washing tank 1213. The chemical washing pump 1212 pumps chemicals between the high-pressure pump 1208 and the reverse osmosis unit 1209 to provide chemical washing for the reverse osmosis unit 1209. The reverse osmosis unit 1209 is also equipped with a concentrated water discharge regulating valve for discharging purified high-salt concentrated water, and a flushing valve for discharging chemical washing flushing water. A pipe is connected to the drainage ditch 6 to the diversion tank 1201 for replenishing water to the water purification equipment 12.

[0035] The water purification device 12 also includes an input device 13, which is connected between the security filter 1207 and the high-pressure pump 1208 for adding bactericide and scale inhibitor into the water purification device 12.

[0036] The raw water is from the drainage ditch 6, and after the drainage ditch 6 is filtered through the gravel filter tank, the raw water enters the drainage tank 1201. The style of the gravel filter tank is referred to Figure 10 The gravel wrapped by the metal filter screen can also be in other forms. The drainage tank 1201 plays a role of negative pressure water pumping. The conductivity sensor is arranged in the drainage tank 1201 to monitor the conductivity of the raw water in real time. The raw water in the drainage tank 1201 is pumped by the source water pump 1202 and enters a plurality of filters in turn. The first bag filter 1203 traps impurities such as suspended solids, microorganisms and organic matters above 300 μm. The second bag filter 1204 traps impurities such as suspended solids, microorganisms and organic matters above 2 μm. The multi-medium filter 1205 is mainly filled with filter materials such as quartz sand and activated carbon to trap impurities such as suspended solids, microorganisms, colloids and organic matters in water. The security filter 1207 traps impurities such as suspended solids, microorganisms and organic matters above 1 μm. The water inlet valve 1206 is arranged between the multi-medium filter 1205 and the security filter 1207. The input device 13 mainly plays a role of conveying bactericides and scale inhibitors into the system to prevent bacteria from breeding on the reverse osmosis device 1209 and mineral precipitation. The reverse osmosis device 1209 filters most inorganic salts, and the desalination rate is above 99.7%. The concentrated water after desalination is discharged through the concentrated water discharge adjusting valve. The pure water tank 1210 is used to store the pure water produced by the reverse osmosis device 1209.

[0037] The chemical washing tank 1213 provides chemical cleaning. Generally, chemical cleaning is performed every 3 months or so. Long-term operation of the equipment can cause microorganisms to adhere to the membrane surface and inorganic salt scaling, resulting in membrane clogging. Chemical cleaning can restore the interception effect of the reverse osmosis membrane. The chemical washing function is selectively used, and the flow direction is controlled through a separately controlled valve.

[0038] The valves, pressure gauges and other devices are arranged between the components of the water purification equipment 12 to cope with maintenance and detection. For example, if the pressure difference between two components is too large, it indicates that a component fails, so that measures can be taken to maintain and repair the component.

[0039] Specific application mode: Branch pipes 3 for drainage are arranged in the field, the branch pipes 3 converge into the main pipe 2, the water in the main pipe 2 enters the water collecting well 1, a part of the water is stored in the water collecting well 1, and the excess water is discharged into the drainage ditch 6 through the pipeline. In order to increase the drainage effect, a plurality of dewatering wells 4 are pre-embedded in the field. The salinity in the dewatering well 4 and the water collecting well 1 is relatively high and can be monitored through the conductivity sensor. The water purification equipment 12 uses the water in the drainage ditch 6 for purification. The water produced by the water purification equipment 12 is close to pure water and has low salinity.

[0040] The crops have different tolerances to salinity at different growth stages, and thus, by controlling the proportion of water in the precipitation well 4, the water collection well 6 and the water purification device 12, the salinity of the irrigation water can be adjusted according to the growth stage of the crops, so as to effectively reduce the irrigation cost and improve the reuse rate of saline-alkali water.

[0041] Therefore, by controlling through the system, when the water in the drainage ditch 6 is input into the water purification device 12, the purified water can flow into the water purification tank 8; the electromagnetic valve B10 and the electromagnetic valve A9 are opened, the saline-alkali water is transported through the water pump 5, the pure water is extracted in proportion through the one-way water pump 801, and the saline-alkali water is mixed with the pure water, and the spiral propeller 702 is used to assist in conveying and stirring, so that the mixed water can be input into the water storage tank 7, and finally the output pipeline connected to the irrigation equipment in the water storage tank 7 can be used for irrigation.

[0042] Embodiment 2

[0043] On the basis of embodiment 1, one preferred structure of the exhaust valve pipe 11 is that side positioning grooves 1101 are arranged on both sides of the exhaust valve pipe 11, and the side positioning grooves 1101 are fixed through a bolt locking structure; the bottom of the exhaust valve pipe 11 is a flange structure, a sliding rod 1102 is fixedly arranged at the bottom of the exhaust valve pipe 11, a floating valve 1103 is slidably arranged outside the sliding rod 1102, and a baffle is fixedly arranged at the bottom of the sliding rod 1102; a plug-in top cover 1104 is clamped at the top of the exhaust valve pipe 11. When the water levels of the precipitation well 4, the water storage tank 7 and the water purification tank 8 rise, air can pass through the middle of the exhaust valve pipe 11 and be discharged, and when the water level is too high, the floating valve 1103 will be floated to block the exhaust valve pipe 11 to prevent the water level from continuing to rise and be discharged, and the plug-in top cover 1104 can block the outside to provide protection.

[0044] Embodiment 3

[0045] On the basis of embodiments 1 and 2, the impeller group 1301 is rotatably arranged in the input device 13 in cooperation with a sealing bearing; the main body of the input device 13 is an eccentric channel, side transmission frames 1302 are fixedly arranged on both sides of the input device 13, and crankshafts 1303 are rotatably arranged in the middle of the input device 13; electric cylinders 1304 are fixedly arranged at the bottom of each side transmission frame 1302, sliding trolleys 1305 are fixedly arranged at the extension ends of the electric cylinders 1304, and linkage gears 1306 are rotatably arranged in the sliding trolleys 1305.

[0046] The upper and lower ends of the input device 13 are fixedly provided with guide sliding rods 1307, and a strip-shaped frame 1308 is slidably arranged between the two guide sliding rods 1307 on the same side. The shaft end of the impeller set 1301 and the shaft end of the crankshaft 1303 are both fixedly provided with combined gears 1309. When the electric cylinder 1304 is extended, the linkage gear 1306 can be engaged with the two combined gears 1309. The two sides of the input device 13 are both fixedly provided with delivery pistons 1310, and the extension ends of the delivery pistons 1310 are both fixedly connected with the strip-shaped frame 1308. The tail ends of the delivery pistons 1310 are both connected with check valves A 1311 and check valves B 1312, and the check valves A 1311 are all connected to the inside of the input device 13. The two check valves B 1312 are respectively connected with a bactericide and a scale inhibitor. The bactericide prevents plankton and microorganisms in water from adhering to the surface of the reverse osmosis membrane and growing, causing membrane hole blockage. The scale inhibitor prevents inorganic matter from being supersaturated on the membrane surface and causing membrane hole blockage.

[0047] When water passes through the input device 13, the impeller set 1301 is driven to rotate. The electric cylinder 1304 is started to move the sliding trolley 1305, so that the linkage gear 1306 is engaged with the combined gear 1309. The crankshaft 1303 can be drivingly connected with the impeller set 1301. The crankshaft 1303 drives the strip-shaped frame 1308 to move forward and backward, repeatedly extruding the delivery pistons 1310. Through variable volume, the check valve B 1312 sucks in the bactericide or the scale inhibitor, which then passes through the check valve A 1311 into the outlet of the input device 13, so as to realize automatic addition. The type of the bactericide and the scale inhibitor input can be adjusted as needed, and the input ratio can be adjusted by controlling the transmission time.

[0048] Example 4:

[0049] The deployment process of examples 1-3 is automatically implemented by a computer system. In a preferred embodiment, a multi-objective optimization scheme based on NSGA-III is used to obtain water from three water sources (water collection well 1, precipitation well 4, and purified water tank 8) to achieve the target total water amount (W) and the target water quality conductivity (EC). The conductivity of the water source of the water collection well 1 and the water source of the precipitation well 4 is not much different and is assumed to be the same and is monitored at any time (C1), while the conductivity of the purified water is a stable known value (C3). The unit of conductivity is millisiemens per centimeter (mS / cm).

[0050] I. Optimization objectives

[0051] 1. Water amount objective 1: meet the total water amount target W

[0052] Ensure that the water amounts V1 (water amount of water collection well 1), V2 (water amount of precipitation well 4), and V3 (water amount of purified water tank 8) extracted from each water source meet the total water amount demand W,

[0053] The formula is as follows:

[0054] V1 + V2 + V3 = W

[0055] Water quality target 2: Achieve target conductivity EC

[0056] By adjusting the water intake of each water source, the conductivity of the mixed water is optimized to be as close to the target conductivity EC as possible,

[0057] The formula is as follows:

[0058] (V1 * C1 + V2 * C1 + V3 * C3) / (V1 + V2 + V3) = EC

[0059] Water quality priority target 3: Minimize the use of high conductivity water sources

[0060] In the optimization process, the use of high conductivity water sources (such as V1 or V2) is reduced to reduce water quality risk and environmental impact. This goal is achieved by reducing the use of V1 and V2 in the optimization process.

[0061] II. Decision variables and constraints

[0062] The main decision variables in the optimization process are the water intake of each water source V1, V2 and V3. The goal is to optimize the multi-objective function by adjusting these decision variables. The following constraints need to be met:

[0063] Water quantity constraint: water balance constraint

[0064] V1 + V2 + V3 = W

[0065] Water quality constraint: conductivity balance constraint

[0066] V1 * C1 + V2 * C1 + V3 * C3 = EC * W

[0067] Water quality background value constraint: non-negativity constraint

[0068] V1 ≥ 0, V2 ≥ 0, V3 ≥ 0

[0069] Specific use and effect of the invention: In the invention, branch pipes 3 for drainage are set up in the field, the branch pipes 3 converge into the main pipe 2, the water body in the main pipe 2 enters the water collecting well 1, a part of the water collecting well 1 is stored, and the excess is discharged into the drainage ditch 6 through the pipeline. To increase the drainage effect, a plurality of precipitation wells 4 are also pre-buried in the field;

[0070] The salinity in the precipitation well 4 and the water collecting well 1 is relatively high, and can be monitored by the conductivity sensor, while the water body produced by the water purification equipment 12 is close to pure water, the salinity is low, and the conductivity is a stable known value;

[0071] Thus, through the system control, when the water is purified, the ditch water in the drainage ditch 6 is input into the water purification device 12, and the purified water can flow into the water purification tank 8; open the electromagnetic valve B10 and the electromagnetic valve A9, transport the saline water through the water pump 5, open the one-way water pump 801 to extract pure water in proportion, mix it with saline water, and use the screw propeller 702 to assist transportation and stirring, which can input the mixed water into the water storage tank 7, and finally set up the output pipeline in the water storage tank 7 to connect the irrigation equipment for irrigation;

[0072] When the water level in the water collecting well 1 is too high, it will flow into the drainage ditch 6 to be discharged, and when the water level in the precipitation well 4, the water storage tank 7 and the water purification tank 8 rises, the air can pass through the middle of the air vent valve pipe 11 to be discharged, and when the water level is too high, the floating valve 1103 will be floated to block the air vent valve pipe 11 to avoid the water level to continue to rise and be discharged, and the plug-in top cover 1104 can block the outside to provide protection;

[0073] During water purification, when the water passes through the inputter 13, it drives the impeller set 1301 to rotate; start the electric cylinder 1304 to move the sliding turret 1305, engage the linkage gear 1306 with the combined gear 1309, which can drive the crankshaft 1303 and the impeller set 1301, the crankshaft 1303 drives the strip frame 1308 to move back and forth, repeatedly extruding the delivery piston 1310, through the variable volume, using the one-way valve B1312 to suck the bactericide or scale inhibitor, and then passing through the one-way valve A1311 into the outlet of the inputter 13, realizing automatic addition, and can adjust the input type of bactericide and scale inhibitor according to needs, and can adjust the input proportion by controlling the transmission time.

Claims

1. A system for preparing and reusing saline-alkali water in farmland, characterized in that, include: A water collection well (1) is provided with a main pipe (2) connected to the upper outer side of the water collection well (1). Branch pipes (3) are fixedly connected to both sides of the main pipe (2). A barrier cotton cover (301) is fixedly installed above each branch pipe (3). A dewatering well (4) is provided with a sealing cover fixedly installed on the top of the dewatering well (4). A water pump (5) is fixedly connected to the top of the dewatering well (4) and the top of the water collection well (1). A suction pipe is provided at the input end of the water pump (5) and connected to the lower interior of the water collection well (1) and the dewatering well (4). A water storage tank (7) is provided with a fixed lower side of the water storage tank (7). There is an input device (701), and a pipe is provided on the top of the water pump (5) to connect to the top of the input device (701). A branch is also provided in the pipe to connect to the water purification tank (8); a conductivity sensor is provided in the water collection well (1), the dewatering well (4) and the water storage tank (7); a water purification device (12) is provided, which includes a diversion tank (1201), a source water pump (1202), a primary bag filter (1203), a secondary bag filter (1204), a multi-media filter (1205), an inlet valve (1206), and a security filter, which are connected in sequence by pipes. The device (1207) and the high-pressure pump (1208) are connected; the high-pressure pump (1208) is connected to the reverse osmosis device (1209), and the reverse osmosis device (1209) is connected to the pure water tank (1210); a pipe is also provided outside the water collection well (1) to connect to the drainage ditch (6), and a pipe is provided in the drainage ditch (6) to connect to the diversion tank (1201). A pipe is provided on the top of the purified water tank (8) to connect to the outlet of the pure water tank (1210), and a one-way water pump (801) is connected to the outlet of the purified water tank (8); the pipe between the water collection well (1) and the drainage ditch (6) is lower than the main pipe (2), and the water collection well (1) and the drainage ditch (6) are connected to the main pipe (2). The top of the well (4), the water storage tank (7) and the clean water tank (8) are all fixedly equipped with an exhaust valve pipe (11); the two sides of the exhaust valve pipe (11) are provided with side positioning grooves (1101), and the side positioning grooves (1101) are fixed by bolt locking structure; the bottom of the exhaust valve pipe (11) is a flange structure, and a sliding rod (1102) is fixedly provided at the bottom of the exhaust valve pipe (11), a floating valve (1103) is slidably provided on the outside of the sliding rod (1102), and a baffle is fixedly provided at the bottom of the sliding rod (1102); the top of the exhaust valve pipe (11) is fitted with a plug-in top cover (1104). The water purification equipment (12) also includes an input device (13), which is connected between the security filter (1207) and the high-pressure pump (1208) for conveying bactericide and scale inhibitor to the water purification equipment (12); the input device (13) has an impeller assembly (1301) rotatably mounted inside with a sealed bearing; the main body of the input device (13) is an eccentric channel, and side transmission frames (1302) are fixedly mounted on both sides of the input device (13), and a crankshaft (1303) is rotatably mounted in the middle of the input device (13); an electric cylinder (1304) is fixedly mounted at the bottom of the side transmission frame (1302), and a sliding rotating frame (1305) is fixedly mounted at the telescopic end of the electric cylinder (1304), and a linkage gear (1306) is rotatably mounted in the sliding rotating frame (1305); the upper and lower ends of both sides of the input device (13) Guide slide rods (1307) are fixedly mounted on each side, and a strip frame (1308) is slidably arranged between the two sets of guide slide rods (1307) on the same side; a combination gear (1309) is fixedly mounted on the shaft end of the impeller assembly (1301) and the shaft end of the crankshaft (1303); when the electric cylinder (1304) extends, the linkage gear (1306) can mesh with the two sets of combination gears (1309); a conveying piston (1310) is fixedly mounted on both sides of the input device (13), and the telescopic ends of the conveying piston (1310) are fixedly connected to the strip frame (1308); a one-way valve A (1311) and a one-way valve B (1312) are connected to the tail end of the conveying piston (1310), and the one-way valve A (1311) is connected to the inside of the input device (13); the one-way valves B (1312) on both sides are connected to the bactericide and the scale inhibitor, respectively; The input device (701) is internally sealed and rotatably equipped with a screw propeller (702) driven by a motor. The allocation process is automatically implemented by a computer system, based on the multi-objective optimization scheme of NSGA-III, to obtain water from the collection well (1), the dewatering well (4) and the purification tank (8); The optimization goals are set as follows: Water quantity target 1: Satisfy the total water quantity target W, as shown in the following formula: V1 + V2 + V3 = W, In the formula, V1 is the water volume extracted by the collection well (1), V2 is the water volume extracted by the dewatering well (4), and V3 is the water volume extracted by the purification tank (8); Water quality target 2: Achieve target conductivity EC. The formula is as follows: (V1*C1+V2*C1+V3*C3) / (V1+V2+V3)=EC, In the formula, C1 is the water conductivity EC of the collection well (1) and the dewatering well (4), and C3 is the water conductivity EC of the purification tank (8); Water quality priority objective 3: Minimize the use of water sources with high electrical conductivity; The decision variables and constraints are set as follows: The decision variables in the optimization process are the water intake volumes V1, V2, and V3 for each water source. The goal is to optimize a multi-objective function by adjusting these decision variables, which requires satisfying the following constraints: Water quantity constraint: Water balance constraint V1 + V2 + V3 = W, Water quality constraints: conductivity balance constraints. V1*C1+V2*C1+V3*C3=EC*W, Water quality background value constraint: non-negativity constraint. V1≥0, V2≥0, V3≥0.

2. The farmland saline-alkali water preparation and reuse system as described in claim 1, characterized in that, A solenoid valve A (9) is connected to the outlet of the one-way water pump (801).

3. The farmland saline-alkali water preparation and reuse system as described in claim 1, characterized in that, The input terminal of the input device (701) is also connected to a solenoid valve B (10).

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