Sewage treatment system for instable water inflow

Abstract

The invention relates to a sewage treatment system for unstable inflow water, which comprises a regulating tank, an intermediate regulation and control tank, a biochemical treatment unit and a post-treatment unit which are connected in sequence, and unstable inflow water sewage enters the regulating tank for homogeneous regulation; the middle regulation and control pool comprises an overflow area, a water inlet area and a water outlet area which are sequentially arranged, a water outlet pipe of the regulation pool is connected with the water inlet area, the bottom of the downstream side of the water inlet area is connected with the water outlet area, an overflow plate is arranged between the upstream side of the water inlet area and the overflow area, and a water outlet pipe of the overflow area is connected with the regulation pool and used for controlling the flow of outlet water of the regulation pool; the biochemical treatment unit comprises an anaerobic tank, a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank and a second-stage aerobic tank which are connected in sequence, and is used for carrying out biochemical treatment on effluent of the regulating tank; the post-treatment unit comprises a sedimentation tank and is used for carrying out mud-water separation on the water body subjected to biochemical treatment to obtain produced water.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a sewage treatment system for unstable water inflow. Background Art

[0002] In sewage treatment, unstable water inflow includes two main factors: unstable water inflow and unstable water quality. For example, unstable water inflow is common in rural sewage treatment. Unstable water inflow includes large changes in water flow at different times of the day, and large fluctuations in water inflow throughout the year. Especially when it rains, rainwater often enters the pipe network, causing large changes in water volume and quality. The unstable water quality of the inflow is due to the small rural population, and the water quality varies greatly at different times of the day. At the same time, in the summer, the pipe network seeps into groundwater or rainwater pours into the pipe network, which also causes water quality fluctuations.

[0003] The above unstable water inflow brings difficulties to traditional sewage treatment equipment, often resulting in adverse consequences such as effluent quality exceeding the standard and loss of microorganisms in the system. Summary of the invention

[0004] In view of the above problems, the present invention provides a sewage treatment system for unstable water inflow, comprising a regulating tank, an intermediate regulating tank, a biochemical treatment unit and a post-treatment unit connected in sequence, wherein the unstable water inflow sewage enters the regulating tank for homogenization regulation; the intermediate regulating tank comprises an overflow area, an inlet area and an outlet area arranged in sequence, the outlet pipe of the regulating tank is connected to the inlet area, the bottom of the downstream side of the inlet area is connected to the outlet area, an overflow plate is provided between the upstream side of the inlet area and the overflow area, and the outlet pipe of the overflow area is connected to the regulating tank for controlling the flow rate of the outlet water of the regulating tank;

[0005] The biochemical treatment unit includes an anaerobic tank, a primary anoxic tank, a primary aerobic tank, a secondary anoxic tank and a secondary aerobic tank which are connected in sequence to perform biochemical treatment on the effluent from the regulating tank; the post-treatment unit includes a sedimentation tank to separate mud and water from the water after biochemical treatment to obtain produced water.

[0006] Optionally, an overflow plate is provided on the upstream side of the water inlet area, and a water outlet orifice plate is provided on the downstream side, and the top of the overflow plate is lower than the top of the water outlet orifice plate. If the amount of water in the water inlet area is too large, it overflows into the overflow area through the overflow plate and then returns to the regulating tank;

[0007] A plurality of water outlet holes are evenly arranged at the lower part of the water outlet hole plate, which are used to connect the water inlet area and the water outlet area.

[0008] Optionally, a nitrification liquid reflux pipe is connected between the secondary aerobic tank and the primary anoxic tank to return the nitrification liquid from the aerobic tank to the anoxic tank; a sludge reflux pipe is connected between the sedimentation tank and the anaerobic tank to return part of the sludge obtained by precipitation to the anaerobic tank to replenish the sludge amount.

[0009] Optionally, a diversion and mixing device is provided in the middle of the anaerobic tank, the lower part of the diversion and mixing device is connected to the outlet pipe of the water outlet area, and the top is connected to the outlet of the sludge return pipe, which is used to evenly mix the inlet water of the anaerobic tank with the returned sludge; a stirring device is provided on the upstream side of the anaerobic tank, which is used to continue mixing the mud-water mixed flow output by the diversion and mixing device with the water in the anaerobic tank to promote anaerobic biochemical treatment.

[0010] Further optionally, the diversion mixing device includes a diversion tube and a first stirring part and a second stirring part inside the diversion tube, the water pipe of the water outlet area connected to the anaerobic tank is connected to the bottom of the diversion tube, and the outlet of the sludge return pipe is connected to the top of the diversion tube; the stirring paddle of the first stirring part is a continuous single spiral stirring blade, which can continuously transport the sludge transported by the sludge return pipe downward in the diversion tube;

[0011] The gas separation part and the second stirring part are arranged below the first stirring part. After the sewage input to the bottom of the guide tube is stirred by the second stirring part, the flow rate is increased, and then part of the oxygen-containing gas is separated by the gas separation part, and then the water body continues to move upward and mix with the sludge;

[0012] The side wall of the guide tube is provided with an outlet for outputting the mixed sewage and sludge.

[0013] Further optionally, the gas separation part includes a conical separation cover and an exhaust pipe, the separation cover is small at the top and large at the bottom, and is conical, the separation cover is concentrically arranged with the guide tube, and there is a gap between the bottom edge of the separation cover and the inner wall of the guide tube, allowing the sewage in the guide tube to pass through the separation cover;

[0014] At least two exhaust pipes are connected to the top of the separation cover. The exhaust pipes pass through the guide tube and extend along the outer wall of the guide tube to above the liquid level of the anaerobic tank to discharge the gas separated by the separation cover. The exhaust pipes can be connected to the position of the fixed separation cover.

[0015] Further optionally, an expansion part is provided between the gas separation part and the second stirring part, and the diameter of the guide tube part corresponding to the expansion part is larger than the diameter of other parts of the guide tube, so that the inside of the expansion part expands outwards;

[0016] The ratio of the inner diameter of the non-expansion part of the guide tube to the inner diameter of the expansion part is 1:(1.5-2), and the height of the expansion part accounts for 50-75% of the height of the guide tube part between the gas separation part and the second stirring part.

[0017] Optionally, a stirring device is provided between the upstream side of the anaerobic tank and the guide cylinder, the stirring shaft of the stirring device is vertically arranged and the top is connected to a third motor above the anaerobic tank, a plurality of mixing and stirring pieces are provided at the position of the stirring shaft corresponding to the outlet, and the plurality of mixing and stirring pieces are evenly arranged along the circumference of the stirring shaft;

[0018] The mixing and stirring element is hemispherical and concave toward the stirring axis and is hollow. The circular surface of the opening of the mixing and stirring element is vertical and passes through the center of the sphere. The opening of the mixing and stirring element faces away from the stirring axis. The outlet is between the highest point of the opening of the mixing and stirring element and the center of the sphere.

[0019] Optionally, the outlet of the nitrification liquid reflux pipe is provided with a reducer, the diameter of the reducer gradually decreases from top to bottom, the reducer is inclined and inclined toward the downstream side of the primary anoxic tank, and the reducer is at the bottom of the primary anoxic tank;

[0020] An inclined plate is provided at the bottom of the downstream side of the first-stage anoxic tank, which is conducive to changing the flow direction of the pressurized water output by the reducer, driving the water in the first-stage anoxic tank to form a rotating state and promoting the contact between sludge and sewage.

[0021] Optionally, the post-treatment unit includes a primary sedimentation tank, a coagulation tank and a secondary sedimentation tank connected in sequence, an air lift device is provided at the bottom of the primary sedimentation tank, the air lift device is connected to a sludge return pipe, and produced water is discharged from the top of the secondary sedimentation tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural diagram of a sewage treatment system for unstable water inflow;

[0023] Figure 2 is a schematic diagram of a flow-guiding mixing device;

[0024] Figure 3 It is a schematic diagram of the stirring device in the anaerobic tank;

[0025] Figure 4 Schematic diagram of another flow-guiding mixing device of Example 1.

[0026] In the attached drawings, 1-regulating tank, 2-intermediate regulating tank, 3-overflow area, 4-water inlet area, 5-water outlet area, 6-anaerobic tank, 7-primary anoxic tank, 8-primary aerobic tank, 9-secondary anoxic tank, 10-secondary aerobic tank, 11-water outlet orifice plate, 12-nitrification liquid return pipe, 13-sludge return pipe, 14-guide tube, 15-first stirring part, 16-second stirring part, 17-outlet, 18-separation cover, 19-exhaust pipe, 20-stirring shaft, 21-mixing stirring member, 22-opening, 23-fourth motor, 24-connecting shaft, 25-reducing pipe, 26-inclined plate, 27-first aeration device, 28-second aeration device, 29-pre-sedimentation tank, 30-primary sedimentation tank, 31-coagulation tank, 32-secondary sedimentation tank, 33-expansion part. DETAILED DESCRIPTION

[0027] This embodiment provides a sewage treatment system for unstable water inflow, such as Figure 1-Figure 3As shown, it includes a regulating tank 1, an intermediate regulating tank 2, a biochemical treatment unit and a post-treatment unit connected in sequence, and unstable influent sewage enters the regulating tank 1 for homogenization regulation; the intermediate regulating tank 2 includes an overflow area 3, an inlet area 4 and an outlet area 5 arranged in sequence, the outlet pipe of the regulating tank 1 is connected to the inlet area 4, the bottom of the downstream side of the inlet area 4 is connected to the outlet area 5, an overflow plate is provided between the upstream side of the inlet area 4 and the overflow area 3, and the outlet pipe of the overflow area 3 is connected to the regulating tank 1 for controlling the flow rate of the outlet water of the regulating tank 1;

[0028] The biochemical treatment unit includes an anaerobic tank 6, a primary anoxic tank 7, a primary aerobic tank 8, a secondary anoxic tank 9 and a secondary aerobic tank 10 which are connected in sequence to perform biochemical treatment on the effluent from the regulating tank 1; the post-treatment unit includes a sedimentation tank to separate mud and water from the water after the biochemical treatment to obtain produced water.

[0029] Optionally, a circulating mixer and a sewage lifting pump are provided in the regulating tank 1 , and the sewage lifting pump is connected to the outlet pipe of the regulating tank 1 and then connected to the water inlet area 4 of the intermediate regulating tank 2 .

[0030] If unstable sewage is directly subjected to biochemical treatment, it will cause impact on the biochemical system. The treatment effect will be poor when the water volume is large, and excessive treatment will be performed when the water volume is small, wasting energy. Unstable influent enters the regulating tank 1 for buffering, mixing, and homogenization. The impeller of the circulation mixer rotates horizontally, driving the sewage to flow downward quickly, flushing the bottom of the regulating tank 1 to prevent sludge precipitation, and forming a circulating stirring to homogenize the sewage.

[0031] Optionally, an overflow plate is provided on the upstream side of the water inlet area 4, and a water outlet orifice plate 11 is provided on the downstream side, and the top of the overflow plate is lower than the top of the water outlet orifice plate 11. If the amount of water in the water inlet area 4 is too large, it overflows into the overflow area 3 through the overflow plate and then returns to the regulating tank 1;

[0032] A plurality of water outlet holes are evenly arranged at the lower part of the water outlet plate 11 for connecting the water inlet area 4 and the water outlet area 5 .

[0033] The intermediate control tank 2 is used to control the amount of sewage entering the subsequent biochemical treatment unit. The overflow plate and the outlet orifice plate 11 divide the intermediate control tank 2 into three areas, namely the overflow area 3, the water inlet area 4 and the water outlet area 5. The sewage transported by the sewage lifting pump first enters the water inlet area 4 for buffering, then flows to the water outlet area 5 through the outlet holes on the outlet orifice plate 11, and then enters the anaerobic tank 6.

[0034] The diameter of the water outlet hole is 10-20 mm, and the number and diameter of the water outlet holes are determined by the average water inflow. The pressure of the outflow from the water outlet hole comes from the liquid level difference between the water inlet area 4 and the water outlet hole position. According to the average water inflow, the number, diameter and liquid level difference of the water outlet holes can be calculated. The overflow plate discharges the excess sewage from the water inlet area 4 to the overflow area 3, and then returns it to the regulating tank 1 in time.

[0035] Optionally, a nitrification liquid return pipe 12 is connected between the secondary aerobic tank 10 and the primary anoxic tank 7 to return the nitrification liquid from the aerobic tank to the anoxic tank; a sludge return pipe 13 is connected between the sedimentation tank and the anaerobic tank 6 to return part of the sludge obtained by precipitation to the anaerobic tank 6 to replenish the sludge amount.

[0036] Optionally, a diversion mixing device is provided in the middle of the anaerobic tank 6, the lower part of the diversion mixing device is connected to the outlet pipe of the water outlet area 5, and the top is connected to the outlet of the sludge return pipe 13, which is used to evenly mix the influent of the anaerobic tank 6 with the returned sludge; a stirring device is provided on the upstream side of the anaerobic tank 6, which is used to continue mixing the mud-water mixed flow output by the diversion mixing device with the water in the anaerobic tank 6 to promote anaerobic biochemical treatment;

[0037] A first connecting pipe is provided at the top of the downstream side of the anaerobic tank 6 for connecting to the bottom of the upstream side of the primary anoxic tank 7 to input the water treated in the anaerobic tank 6 into the primary anoxic tank 7 .

[0038] Further optionally, the diversion mixing device includes a diversion tube 14 and a first stirring part 15 and a second stirring part 16 inside the diversion tube 14, the water pipe connecting the water outlet area 5 to the anaerobic tank 6 is connected to the bottom of the diversion tube 14, and the outlet of the sludge return pipe 13 is connected to the top of the diversion tube 14; the stirring paddle of the first stirring part 15 is a continuous single spiral stirring blade, which can continuously transport the sludge transported by the sludge return pipe 13 downward in the diversion tube 14;

[0039] A gas separation part and a second stirring part 16 are provided below the first stirring part 15 in sequence. After the sewage input to the bottom of the guide tube 14 is stirred by the second stirring part 16, the flow rate is increased, and then part of the oxygen-containing gas is separated by the gas separation part, and then the water body continues to move upward and mix with the sludge;

[0040] The side wall of the guide tube 14 is provided with an outlet 17 for outputting the mixed sewage and sludge.

[0041] Further optionally, the guide tube 14 is cylindrical as a whole, the top of the guide tube 14 is open and higher than the liquid level of the anaerobic tank 6, so that the sludge return pipe 13 can input the returned sludge into the top of the guide tube 14, and the bottom of the guide tube 14 is at the bottom of the anaerobic tank 6;

[0042] The top of the rotating shaft of the first stirring part 15 extends upward from the liquid surface of the anaerobic tank 6 and is connected to the first motor above the anaerobic tank 6 to drive the first stirring part 15 to rotate; the bottom of the rotating shaft of the second stirring part 16 is connected downward to the second motor, which is arranged at the bottom of the guide tube 14 and is used to drive the second stirring part 16 to rotate.

[0043] Further optionally, the gas separation part includes a conical separation cover 18 and an exhaust pipe 19. The separation cover 18 is small at the top and large at the bottom, and is conical. The separation cover 18 is concentrically arranged with the guide tube 14. There is a gap between the bottom edge of the separation cover 18 and the inner wall of the guide tube 14, allowing the sewage in the guide tube 14 to pass through the separation cover 18;

[0044] At least two exhaust pipes 19 are connected to the top of the separation cover 18. The exhaust pipes 19 pass through the guide tube 14 and extend along the outer wall of the guide tube to above the liquid level of the anaerobic tank 6 to discharge the gas separated by the separation cover 18. The exhaust pipes 19 can be connected to the position of the fixed separation cover 18.

[0045] Preferably, each exhaust pipe 19 is installed symmetrically with the center of the separation cover 18 as the center, which can not only evenly distribute the exhaust gas but also facilitate the stable installation of the separation cover 18.

[0046] Further optionally, the second stirring part 16 includes a plurality of evenly distributed stirring blades to form a conventional impeller, and the impeller is disposed horizontally as a whole to provide stirring power for the sewage inputted below.

[0047] The sewage from the outlet area 5 is input to the bottom of the guide tube 14. The sewage flows upward under the stirring of the second stirring part 16. After passing through the second stirring part 16, the water flow speed is accelerated and flows upward in a spiral. Under a large flow rate and spiral stirring state, it is conducive to the discharge of gas in the sewage (the gas contains oxygen, which is not conducive to the biochemical reaction of the anaerobic tank 6). When the sewage reaches the separation cover 18, the separation cover 18 performs gas-liquid separation, and the separated liquid continues to flow upward from the edge of the separation cover 18, and the separated gas is discharged from the anaerobic tank 6 through each exhaust pipe 19. The water body rushing into the separation cover 18 is in a rotating upward shape, and the separation cover 18 is also in a cone shape with an opening downward, which is conducive to the continued rotation of the rising water body in the separation cover 18, which is conducive to gas-liquid separation. The separated gas also keeps rotating, and the exhaust pipes 19 in all directions are convenient for receiving the gas and quickly discharging the gas.

[0048] The sewage passing through the separation cover 18 continues to flow upward in a spiral shape, and the sludge return pipe 13 outputs the sludge mixture (sludge and water) to the spiral stirring blades of the first stirring section 15. Driven by the first stirring section 15, the spiral is input downward. The first stirring section 15 rotates in opposite directions to the second stirring section 16. At the bottom of the first stirring section 15, the sludge flow and the sewage flow in opposite directions meet, forming a more violent disturbance, which promotes the mixing of mud and water. The rotation speed of the two stirring sections and the flow rate of the sewage entering the guide tube 14 are adjusted so that the sewage has greater kinetic energy and can rise to a position close to the top of the guide tube 14, but does not overflow at the top of the guide tube 14, so that the sewage can be mixed with the sludge over most of the length of the first stirring section 15.

[0049] Optionally, along the length direction of the first stirring part 15, from top to bottom, the sludge concentration gradually decreases, and the sludge is gradually evenly dispersed in the sewage. The height of the outlet 17 corresponds to the height of the middle part of the first stirring part 15. The sludge concentration in the middle part of the first stirring part 15 is moderate, and the mixing effect of sewage and sludge is better. It is suitable to discharge the mud-water mixture at this height;

[0050] The outlet 17 faces the upstream side of the anaerobic tank 6, which is conducive to the mud-water mixture directly entering the area near the upstream part of the anaerobic tank 6 to contact and react with the anaerobic sludge.

[0051] The present invention comprehensively considers factors such as the sedimentation properties of sludge and the rising flow rate of sewage. Under the stirring action of the first stirring section 15 and the flow and rotation of the sewage that has just separated from the separation cover 18, the rising sewage is mixed with the descending sludge. The sludge concentration is higher in the area near the top or upper part of the guide tube 14, and the degree of mixing with the sewage from the intermediate control tank 2 is lower. The area near the bottom of the first stirring section 15 is mostly sewage, and the muddy water is in the initial mixing stage. The rising sewage impacts and lifts the sludge. In the area near the middle of the first stirring section 15, the degree of mixing between sewage and sludge is better, and an outlet 17 is provided here to discharge the logistics with good muddy water mixing into the anaerobic tank 6.

[0052] Optionally, a stirring device is provided between the upstream side of the anaerobic tank 6 and the guide tube 14, the stirring shaft 20 of the stirring device is vertically arranged and the top is connected to the third motor above the anaerobic tank 6, and the stirring shaft 20 is provided with a plurality of mixing and stirring members 21 at the position corresponding to the outlet 17, and the plurality of mixing and stirring members 21 are evenly arranged along the circumference of the stirring shaft 20;

[0053] The mixing and stirring element 21 is hemispherical and concave toward the stirring shaft 20 and is hollow. The circular surface of the opening 22 of the mixing and stirring element 21 is vertical and passes through the center of the sphere. The opening 22 of the mixing and stirring element 21 faces away from the stirring shaft 20. The outlet 17 is between the highest point of the opening of the mixing and stirring element 21 and the center of the sphere.

[0054] Further optionally, a hollow cavity is provided on the stirring shaft 20, and a plurality of fourth motors 23 are provided in the hollow cavity. The number of the fourth motors 23 is equal to the number of the mixing and stirring elements 21. Each fourth motor 23 is connected to a mixing and stirring element 21 for driving the mixing and stirring element 21 to rotate. The fourth motor is a micro motor.

[0055] Further optionally, the vertex of the spherical surface of the mixing and stirring element 21 is connected to the corresponding fourth motor in the hollow cavity through a connecting shaft 24, the vertex is located on a horizontal circular surface where the center of the sphere is located, the radius of the circular surface is equal to the radius of the mixing and stirring element 21, and the connecting shaft is horizontal and penetrates into the hollow cavity to connect to the corresponding fourth motor;

[0056] The apexes of the spherical surfaces of all the mixing and stirring elements 21 are at the same height.

[0057] The third motor drives all the mixing and stirring elements 21 to rotate horizontally through the stirring shaft 20, and the circular openings (vertical) of the mixing and stirring elements 21 continuously and alternately face the outlet 17 of the guide tube 14. The mixing and stirring elements 21 are vertically placed hemispherical (similar to a bowl shape), and the mud-water mixture discharged from the outlet 17 is still in a state of rapid rotation, and along the tangential direction similar to the guide tube 14 (not the standard tangential direction, according to the respective rotation speeds of the first stirring part 15 and the second stirring part 16, the material flow direction of the outlet 17 is closer to the guide tube 14 or farther away from the guide tube 14 compared with the standard tangential direction), the mud-water mixture impacts the concave spherical surface of the mixing and stirring elements 21, and as the mixing and stirring elements 21 rotate themselves and rotate with the stirring shaft 20, the mud-water mixture will rotate spirally along the inner wall of the spherical surface, diffuse radially around the spherical surface, and finally diffuse to separate from the mixing and stirring elements 21 and completely enter the water body of the anaerobic tank 6. The cooperation between the guide tube 14 and the mixing and stirring element 21 of the present invention enables a good mud-water mixing effect, and the mud-water mixture is well mixed with the water inside the anaerobic tank 6 .

[0058] Conventional stirring paddles may also be provided on the stirring shaft 20 below the mixing and stirring element 21 , and the form and number of the stirring paddles are determined according to the actual situation of the anaerobic tank 6 .

[0059] Optionally, the outlet of the nitrification liquid reflux pipe 12 is provided with a reducer 25, the diameter of the reducer 25 gradually decreases from top to bottom, the reducer 25 is inclined, and is inclined toward the downstream side of the primary anoxic pool 7, and the reducer 25 is at the bottom of the primary anoxic pool 7;

[0060] An inclined plate 26 is provided at the bottom of the downstream side of the primary anoxic tank 7, which is conducive to changing the flow direction of the pressurized water output by the reducer 25, driving the water in the primary anoxic tank 7 to form a rotating state, and promoting the contact between sludge and sewage;

[0061] A second connecting pipe is provided at the top of the downstream side of the primary anoxic pool 7 for connecting to the bottom of the upstream side of the primary aerobic pool 8 to input the water treated in the primary anoxic pool 7 into the primary aerobic pool 8 .

[0062] An anoxic environment is provided in the primary anoxic tank 7. The water with high oxygen content in the nitrification liquid return pipe 12 and the water with low oxygen content in the anaerobic tank 6 enter the primary anoxic tank 7 at the same time to form a mixed solution. By adjusting the amount of nitrification liquid return water, the dissolved oxygen value of the mixed solution is controlled to be 0.3-0.5 mg / L.

[0063] The present invention designs a reducer 25, which is at an angle of 20 to 30 degrees to the horizontal plane, and its water outlet direction is also output at an angle of 20 to 30 degrees. The reducer 25 can speed up the water flow, output high-speed water flow (large momentum), form a negative pressure area around the outlet of the reducer 25, and form a small-scale water flow area that rotates violently. The tiny nitrogen bubbles generated by the biochemical reaction in the primary anoxic pool 7 can quickly escape from the water body after contacting the water flow area, forming large bubbles and rising rapidly, avoiding nitrogen accumulation. In conjunction with the inclined plate 26, the inclined plate 26 faces the outlet of the reducer 25, so that the water flow that impacts the surface of the inclined plate 26 forms a basically upward water flow, and the water flow impacts upward to the middle and upper part of the primary anoxic pool 7, and under the action of gravity, it flows downward, thereby forming a rotating state, which has a stirring effect on the water body and sludge.

[0064] Optionally, a first aeration device 27 is provided at the bottom of the primary aerobic tank 8, and the first aeration device 27 is provided near the downstream side of the primary aerobic tank 8, and the second connecting pipe is located at the upstream side of the primary aerobic tank 8, so that the influent of the primary aerobic tank 8 is pushed upward by the first aeration device 27 to form a circulation similar to that in the primary anoxic tank 7;

[0065] A third connecting pipe is provided at the top of the downstream side of the primary aerobic pool 8 for connecting to the bottom of the upstream side of the secondary anoxic pool 9 to input the water treated in the primary aerobic pool 8 into the secondary anoxic pool 9 .

[0066] Optionally, a circulation agitator is provided in the secondary anoxic tank 9 to stir the water to prevent sludge deposition and to evenly mix the water. The top of the upper conduit of the circulation agitator is 400 to 500 mm away from the liquid surface to prevent the formation of a vortex to inhale air. The top of the downstream side of the secondary anoxic tank 9 is connected to the top of the secondary aerobic tank 10.

[0067] Optionally, a second aeration device 28 is provided at the bottom of the secondary aerobic tank 10, and the second aeration device 28 is provided close to the upstream side of the secondary aerobic tank 10;

[0068] The bottom of the downstream side of the secondary aerobic tank 10 is connected to the pre-sedimentation tank 29, and a sewage lifting pump is provided in the pre-sedimentation tank 29, and the outlet of the sewage lifting pump is connected to the nitrification liquid reflux pipe 12; the top of the downstream side of the pre-sedimentation tank 29 is provided with a water outlet for connecting to the sedimentation tank.

[0069] The second aeration device 28 aerates upward to form a circulation, but the water flow velocity at the bottom of the downstream side of the secondary aerobic tank 10 is relatively low, which is conducive to the sedimentation of sludge and forms a concentrated sludge area. The pre-sedimentation tank 29 is connected to the bottom of the downstream side of the secondary aerobic tank 10. The nitrified liquid in the secondary aerobic tank 10 is concentrated in the pre-sedimentation tank 29 and refluxed to the primary anoxic tank 7 through the nitrified liquid reflux pipe 12. At the same time, the pre-sedimentation tank 29 can screen the flocculating sludge, which contains a large number of beneficial bacteria in the nitrification process of the aerobic tank and the denitrification process of the anoxic tank, preventing the beneficial bacteria from entering the subsequent sedimentation tank. The flocculating sludge is precipitated at the bottom of the pre-sedimentation tank 29 and refluxed through the nitrified liquid reflux pipe 12. Other loose sludge that is not easy to precipitate enters the sedimentation tank.

[0070] Optionally, the post-treatment unit includes a primary sedimentation tank 30, a coagulation tank 31 and a secondary sedimentation tank 32 connected in sequence, and an air lift device is provided at the bottom of the primary sedimentation tank, and the air lift device is connected to the sludge return pipe 13; the primary sedimentation tank, the coagulation tank and the secondary sedimentation tank are conventionally arranged, and the produced water is discharged from the top of the secondary sedimentation tank.

[0071] The following example treats domestic sewage from a village in Henan Province, which has the characteristics of unstable water inflow. The instantaneous water inflow is the largest in the morning, afternoon and evening time periods, and the water inflow is very small at night. The average water inflow during the peak period is 10.6m 3 / h, the average water inflow during the low period is 1.5m 3 / h, the ratio of the two is about 7 times. Through the effective regulation of the regulating pool, the water flow rate is stabilized at 4.3m 3 / h, and the fluctuation is very small, ensuring uniform water discharge from the regulating pool throughout the day, and the coefficient of variation of the effluent flow rate is kept within 1.05, achieving the purpose of stabilizing the effluent flow rate of the regulating pool. After regulation in the regulating pool, the effluent COD in the effluent area is stabilized at around 106mg / L, and the coefficient of variation of the effluent concentration is kept within 1.1.

[0072] Anaerobic pool biochemical treatment parameters: water flow rate is stable at 4.3m 3 / h, COD influent concentration is 106mg / L, ammonia nitrogen influent concentration is 23mg / L, and anaerobic tank sludge concentration SV30 value is 50%~60%.

[0073] Example 1

[0074] The sewage treatment system for unstable water inflow provided in this embodiment has all the above features, and in addition, Figure 4 As shown, an expansion portion 33 is provided between the gas separation portion and the second stirring portion, and the diameter of the guide tube portion corresponding to the expansion portion is larger than the diameter of other portions of the guide tube, so that the inside of the expansion portion 33 expands outwards;

[0075] The ratio of the inner diameter of the non-expansion part of the guide tube to the inner diameter of the expansion part is 1:1.5, and the height of the expansion part accounts for 50% of the height of the guide tube part between the gas separation part and the second stirring part.

[0076] The rotation speed and flow rate of the sewage passing through the second stirring part are relatively fast, and the separation cover covers most of the cross-section inside the guide tube, which hinders the passage of sewage. The present invention designs an expansion part so that the sewage has a space to remain under the separation cover, avoiding a large amount of sewage directly impacting the separation cover. However, the expansion part will reduce the flow rate of the sewage, so the size of the expansion part is limited, so that the rotation speed and flow rate of the sewage do not drop too much, and at the same time, the flow blocking effect of the separation cover is not too prominent.

[0077] Example 2

[0078] This embodiment provides a sewage treatment system for unstable water inflow, which is the same as Embodiment 1, except that the ratio of the inner diameter of the non-expansion portion of the guide tube to the inner diameter of the expansion portion is 1:2.

[0079] Example 3

[0080] This embodiment provides a sewage treatment system for unstable water inflow, which is the same as Embodiment 1, except that the ratio of the inner diameter of the non-expansion portion of the guide tube to the inner diameter of the expansion portion is 1:2.1.

[0081] Example 4

[0082] This embodiment provides a sewage treatment system for unstable water inflow, which is the same as the embodiment 1, except that the height of the expansion part accounts for 75% of the height of the guide tube part between the gas separation part and the second stirring part.

[0083] Example 5

[0084] This embodiment provides a sewage treatment system for unstable water inflow, which is the same as the embodiment 1, except that the height of the expansion part accounts for 76% of the height of the guide tube part between the gas separation part and the second stirring part.

[0085] Example 6

[0086] This embodiment provides a sewage treatment system for unstable water inflow, which is the same as the first embodiment, except that no expansion part is provided.

[0087] Table 1 Comparison of anaerobic pool treatment effects of Examples 1-6

[0088]

[0089]

[0090] As can be seen from the table above, the setting of the expansion part is conducive to the accumulation of more sewage under the separation cover, avoiding the impact of too fast water flow on the separation cover, which can improve the gas-liquid separation efficiency, reduce the amount of oxygen carried by the sewage, and is conducive to anaerobic biochemical treatment. The appropriate sewage flow rate also improves the mixing effect of sewage and sludge through the first stirring part, making the sewage and sludge more evenly mixed.

Claims

1. A sewage treatment system for unstable water inflow, characterized in that: It includes a regulating tank, an intermediate regulating tank, a biochemical treatment unit and a post-treatment unit connected in sequence, and unstable influent sewage enters the regulating tank for homogeneous regulation; the intermediate regulating tank includes an overflow area, an inlet area and an outlet area arranged in sequence, the outlet pipe of the regulating tank is connected to the inlet area, the bottom of the downstream side of the inlet area is connected to the outlet area, an overflow plate is arranged between the upstream side of the inlet area and the overflow area, and the outlet pipe of the overflow area is connected to the regulating tank for flow control of the outlet water of the regulating tank; The biochemical treatment unit includes an anaerobic tank, a primary anoxic tank, a primary aerobic tank, a secondary anoxic tank and a secondary aerobic tank which are connected in sequence to perform biochemical treatment on the effluent from the regulating tank; the post-treatment unit includes a sedimentation tank to separate mud and water from the water after biochemical treatment to obtain produced water.

2. The sewage treatment system for unstable water inflow according to claim 1, characterized in that: An overflow plate is provided on the upstream side of the water inlet area, and a water outlet orifice plate is provided on the downstream side. The top of the overflow plate is lower than the top of the water outlet orifice plate. If the amount of water in the water inlet area is too large, it will overflow into the overflow area through the overflow plate and then return to the regulating tank; a plurality of water outlet holes are evenly provided at the lower part of the water outlet orifice plate for connecting the water inlet area and the water outlet area.

3. The sewage treatment system for unstable water inflow according to claim 1, characterized in that: A nitrification liquid return pipe is connected between the secondary aerobic tank and the primary anoxic tank for returning the nitrification liquid from the aerobic tank to the anoxic tank; a sludge return pipe is connected between the sedimentation tank and the anaerobic tank for returning the sludge obtained by sedimentation to the anaerobic tank to replenish the sludge volume.

4. The sewage treatment system for unstable water inflow according to claim 3, characterized in that: A diversion and mixing device is provided in the middle of the anaerobic tank, the lower part of which is connected to the outlet pipe of the outlet area, and the top part is connected to the outlet of the sludge return pipe, so as to evenly mix the influent of the anaerobic tank with the returned sludge; a stirring device is provided on the upstream side of the anaerobic tank, so as to continue to mix the mud-water mixed flow output by the diversion and mixing device with the water in the anaerobic tank, so as to promote anaerobic biochemical treatment.

5. The sewage treatment system for unstable water inflow according to claim 4, characterized in that: The diversion mixing device comprises a diversion tube and a first stirring part and a second stirring part inside the diversion tube, a water pipe in the water outlet area connected to the anaerobic tank is connected to the bottom of the diversion tube, and the outlet of the sludge return pipe is connected to the top of the diversion tube; the stirring paddle of the first stirring part is a continuous single spiral stirring blade, which can continuously transport the sludge transported by the sludge return pipe downward in the diversion tube; A gas separation section and a second stirring section are arranged in sequence below the first stirring section. After the sewage input into the bottom of the guide tube is stirred by the second stirring section, the flow velocity is increased, and then part of the oxygen-containing gas is separated through the gas separation section, and then the water body continues to move upward and mix with the sludge; an outlet is arranged on the side wall of the guide tube for outputting the mixed sewage and sludge.

6. The sewage treatment system for unstable water inflow according to claim 5, characterized in that: The gas separation part includes a conical separation cover and an exhaust pipe. The separation cover is small at the top and large at the bottom, and is conical. The separation cover is concentrically arranged with the guide tube. There is a gap between the bottom edge of the separation cover and the inner wall of the guide tube, allowing the sewage in the guide tube to pass through the separation cover; At least two exhaust pipes are connected to the top of the separation cover. The exhaust pipes pass through the guide tube and extend along the outer wall of the guide tube to above the liquid level of the anaerobic tank to discharge the gas separated by the separation cover. The exhaust pipes can be connected to the position of the fixed separation cover.

7. The sewage treatment system for unstable water inflow according to claim 5, characterized in that: An expansion part is provided between the gas separation part and the second stirring part, and the diameter of the guide tube part corresponding to the expansion part is larger than the diameter of other parts of the guide tube, so that the inside of the expansion part expands outwards; The ratio of the inner diameter of the non-expansion part of the guide tube to the inner diameter of the expansion part is 1:(1.5-2), and the height of the expansion part accounts for 50-75% of the height of the guide tube part between the gas separation part and the second stirring part.

8. The sewage treatment system for unstable water inflow according to claim 4, characterized in that: A stirring device is provided between the upstream side of the anaerobic tank and the guide tube, the stirring shaft of the stirring device is vertically arranged and the top is connected to the third motor above the anaerobic tank, a plurality of mixing and stirring pieces are provided at the position of the stirring shaft corresponding to the outlet, and the plurality of mixing and stirring pieces are evenly arranged along the circumference of the stirring shaft; The mixing and stirring element is hemispherical and concave toward the stirring axis and is hollow. The circular surface of the opening of the mixing and stirring element is vertical and passes through the center of the sphere. The opening of the mixing and stirring element faces away from the stirring axis. The outlet is between the highest point of the opening of the mixing and stirring element and the center of the sphere.

9. The sewage treatment system for unstable water inflow according to claim 3, characterized in that: The outlet of the nitrification liquid reflux pipe is provided with a reducer, the diameter of which gradually decreases from top to bottom, the reducer is inclined and inclined toward the downstream side of the primary anoxic tank, and the reducer is at the bottom of the primary anoxic tank; An inclined plate is provided at the bottom of the downstream side of the first-stage anoxic tank, which is conducive to changing the flow direction of the pressurized water output by the reducer, driving the water in the first-stage anoxic tank to form a rotating state and promoting the contact between sludge and sewage.

10. The sewage treatment system for unstable water inflow according to claim 3, characterized in that: The post-treatment unit comprises a primary sedimentation tank, a coagulation tank and a secondary sedimentation tank which are connected in sequence. An air stripping device is provided at the bottom of the primary sedimentation tank, which is connected to a sludge return pipe. The produced water is discharged from the top of the secondary sedimentation tank.

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