A system suitable for treating rural sewage

Abstract

The present invention relates to the technical field of biological sewage treatment, and in particular to a system suitable for treating rural sewage, the system comprising a biological rotary disc pool, an anoxic pool, an anaerobic pool, a biological contact oxidation pool and a filter pool connected in sequence, a first mixed liquid return pipe is provided between the biological rotary disc pool and the anaerobic pool, and a second mixed liquid return pipe is provided between the biological contact oxidation pool and the anoxic pool. In the process of treating sewage by using the system, three denitrification and three dephosphorization are achieved, and the TP and TN values ​​of the sewage are greatly reduced through multi-stage denitrification and dephosphorization, meeting the discharge standard.

Description

Technical Field

[0001] The present invention relates to the technical field of biological sewage treatment, and in particular to a system and method suitable for treating rural sewage. Background Art

[0002] In general rural sewage treatment processes, the activated sludge method has a long treatment process, occupies a large area, and has a poor sewage treatment effect, while the biofilm method has high maintenance costs and is prone to membrane pollution and other problems.

[0003] Rural sewage includes rural domestic sewage and agricultural sewage. Domestic sewage contains more surfactants, while agricultural sewage contains higher content of nitrogen, phosphorus and organic matter, and has certain toxicity. No matter whether the biofilm method or the activated sludge method is used, it is impossible to effectively reduce the TN and TP indicators of the effluent, resulting in the treated sewage failing to meet the discharge standards. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides a system suitable for treating rural sewage. The system has simple process, low cost, and can effectively remove nitrogen and phosphorus in sewage to meet emission standards.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A system suitable for treating rural sewage, the system comprising a biological rotary disc pool, an anoxic pool, an anaerobic pool, a biological contact oxidation pool and a filter pool connected in sequence, the biological rotary disc pool is provided with a biological rotary disc, the anoxic pool and the anaerobic pool are both provided with a stirring device, the biological contact oxidation pool is provided with a composite filler, and the filter pool is provided with a filtering component; a first mixed liquid return pipe is provided between the biological rotary disc pool and the anaerobic pool, a second mixed liquid return pipe is provided between the biological contact oxidation pool and the anoxic pool, and a mud discharge device is provided at the bottom of the filter pool.

[0007] Furthermore, in the above technical solution, the water inlet ends of the anoxic tank, anaerobic tank, biological contact oxidation tank and filter tank are all provided with baffles, the top of the baffles is higher than the liquid level and the bottom has a gap with the bottom of the tank.

[0008] Furthermore, in the above technical solution, the system includes a first water inlet pipe and a second water inlet pipe, the first water inlet pipe is arranged at the bottom of the biological rotary pool, and the outlet pipe of the second water inlet is located in the anoxic pool.

[0009] Furthermore, in the above technical solution, an aeration pipe is provided at the bottom of the biological contact oxidation pond.

[0010] Furthermore, in the above technical solution, the mud discharge device includes a first mud discharge pipe and a second mud discharge pipe, the first mud discharge pipe is connected to the bottom of the biological rotary tank, and the first mud discharge pipe and the second mud discharge pipe are both connected to a sludge pump.

[0011] Furthermore, in the above technical solution, both the first mixed liquid reflux pipe and the second mixed liquid reflux pipe are connected to a reflux pump.

[0012] Furthermore, in the above technical solution, the filter component is canvas.

[0013] The beneficial effects of the present invention are as follows: (1) The entire treatment system realizes three denitrifications and three dephosphorizations. Through multi-stage denitrification and dephosphorization, the TP and TN values ​​of the sewage are reduced, reaching the national Class IV surface water environmental quality standard. The specific process is as follows: the sewage completes the first denitrification in the biological rotary tank, then enters the anoxic tank to complete the first denitrification, then flourishes the nitrification reaction under the aerobic conditions of the biological contact oxidation tank, and the treated sewage is returned to the anoxic tank for the last denitrification; the sewage completes the first dephosphorization in the biological rotary tank, then enters the anaerobic tank for anaerobic phosphorus release, and then returns to the biological rotary tank for phosphorus accumulation, completing the second dephosphorization, and finally performs phosphorus accumulation in the biological contact oxidation tank to complete the third dephosphorization. (2) The combined process of the mud film mixed biological rotary disk and the inverted A2O has many advantages of both. The essence of the mud film mixed biological rotary disk is that the activated sludge added into the pool provides a huge surface area and a favorable living environment for the attached and growing microorganisms. The enrichment of different functional microorganisms in the reaction tank significantly increases the biomass in the reaction system, thereby changing the microbial structure, types and mass transfer and distribution conditions of the matrix in the mud film mixed biological rotary disk system, and significantly improving the system's processing capacity and efficiency. In the inverted A2O process, since the anoxic tank is set at the front end, it prevents nitrate from affecting the process of inhibiting the release of phosphate by polyphosphate bacteria in the anaerobic tank, effectively enhancing the phosphorus removal efficiency of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the sewage treatment system in the present invention;

[0015] Figure 2 This is a schematic diagram of the operation process of the sewage treatment system; DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] like Figures 1-2As shown, a system suitable for treating rural sewage includes a biological rotary disc pool 1, an anoxic pool 2, an anaerobic pool 3, a biological contact oxidation pool 4 and a filter pool 5 which are connected in sequence. A first mixed liquor return pipe 10 is provided between the biological rotary disc pool 1 and the anaerobic pool 3, a second mixed liquor return pipe 11 is provided between the biological contact oxidation pool 4 and the anoxic pool 2, a return pump is connected to the first mixed liquor return pipe 10 and the second mixed liquor return pipe 11, a mud discharge device 16 is provided at the bottom of the filter pool 5, the mud discharge device 16 includes a first mud discharge pipe 161 and a second mud discharge pipe 162, the first mud discharge pipe 161 is connected to the bottom of the biological rotary disc pool 1, and a sludge pump is connected to the first mud discharge pipe and the second mud discharge pipe.

[0018] The biological rotary disc pool 1 is provided with a mud film mixing biological rotary disc 9, and the biological rotary disc 9 is connected to a motor that can drive the rotary disc to rotate; the bottom end of the biological rotary disc pool 1 is provided with a first water inlet pipe 6, and the bottom of the biological rotary disc pool 1 is provided with activated sludge. The working method of the biological rotary disc pool 1 is as follows: part of the rural sewage enters the biological rotary disc pool 1 from the first water inlet pipe 6, and at the same time, the return pump on the first mixed liquid return pipe 10 is turned on, and the sewage treated in the anaerobic tank is introduced into the biological rotary disc pool 1, and the biological rotary disc 9 is rotated to make the incoming water and the returned sewage fully contact and mix, and provide sufficient dissolved oxygen to the biofilm on the disc, and complete the denitrification reaction through the biofilm, and the treated sewage flows out from the rotary disc into the anoxic tank; moreover, the rotating rotary disc stirs up the sludge at the bottom of the pool, and the returned sludge can replenish the biomass of the rotary disc. The advantages of the biological rotary disk pool 1 in this embodiment are as follows: the mud-film mixed biological rotary disk has the characteristics of high biomass and strong impact load resistance, and can effectively improve the biological denitrification capacity and the ability to remove difficult-to-degrade substances; the activated sludge in the pool and the biological film of the biological rotary disk convert organic nitrogen into ammonia nitrogen through ammonifying microorganisms, and under the action of nitrifying bacteria, the ammonia nitrogen is converted into nitrate nitrogen. The nitrate nitrogen enters the interior of the biofilm and undergoes denitrification reaction under the action of denitrifying bacteria; the biological rotary disk itself has a certain phosphorus removal capacity, and there is an active The sludge accumulates, and the polyphosphate bacteria release phosphorus at the bottom of the tank under anaerobic conditions. The activated sludge is mixed with the sewage through the rotation of the turntable. The biofilm attached to the biological turntable rotates continuously and is exposed to the air. Under aerobic conditions, the polyphosphate bacteria on the biofilm absorb a large amount of phosphorus, so that a large amount of phosphorus is removed from the sewage. The return sludge can reduce the loss of activated sludge in the mud film mixed biological turntable and enhance the sludge concentration. In the mixed liquid returned from the anaerobic tank, under aerobic conditions, the polyphosphate bacteria excessively absorb phosphate in the sewage, thereby removing phosphorus from the sewage and achieving the effect of phosphorus removal.

[0019] The water inlet end of the anoxic pool 2 is provided with a baffle 15, the top of the baffle 15 is higher than the liquid level and the bottom is spaced from the pool bottom, and the two sides of the baffle 13 are fixed on the pool wall; a second water inlet pipe 7 is provided in the anoxic pool 2, and a stirring device 17 is also provided in the anoxic pool 2. The working method of the anoxic pool 2 is as follows: part of the rural sewage is directly introduced into the anoxic pool 2, and enters from the upper water inlet of the pool body in proportion with the sewage treated by the biological rotary pool 1, and completely enters the pool body through the bottom of the baffle, and the stirring device and the reflux pump on the second mixed liquid reflux pipe 11 are turned on, so that the untreated sewage, the sewage treated by the biological rotary pool 1 and the refluxed mixed liquid are fully mixed, and the nitrate nitrogen in the mixed sewage undergoes a denitrification reaction through the action of denitrifying bacteria, and the nitrate nitrogen in the sewage is converted into nitrogen gas, and the denitrification treatment is completed, and the treated sewage flows out from the upper part of the pool body. The inverted anoxic pool design basically converts the nitrate in the sewage into nitrogen gas, so that the nitrate cannot affect the anaerobic phosphorus release process of polyphosphate bacteria.

[0020] The water inlet of the anaerobic tank 3 is also provided with a baffle 15, and the setting method thereof is the same as that of the anoxic tank; a stirring device 17 is provided in the anaerobic tank 3. The working principle of the anaerobic tank 3 is as follows: the sewage treated by the anoxic tank enters from the water inlet at the upper part of the tank body, and completely enters the tank body through the bottom of the baffle. Under anaerobic conditions, polyphosphate bacteria convert organic matter into acetic acid, etc., and release inorganic phosphate into the sewage, completing the phosphorus release process. The treated sewage flows out from the upper part of the tank body, and part of the treated sewage flows back to the biological rotary disc tank 1.

[0021] The water inlet of the biological contact oxidation pool 4 is also provided with a baffle 15, and the setting method thereof is the same as that of the anoxic pool; the bottom of the biological contact oxidation pool 4 is provided with an aeration pipe 14, and a composite filler 12 is suspended in the biological contact oxidation pool 4, and a biofilm is attached to the composite filler 12. The working principle of the biological contact oxidation pool 4 is specifically as follows: the sewage treated by the anaerobic pool 3 enters from the water inlet on the upper part of the pool body, and completely enters the pool through the baffle, and the aeration device is turned on. Under the action of polyphosphate bacteria, excessive phosphorus-containing substances in the sewage are absorbed, and finally separated from the sewage and discharged with the sludge, thereby completing the phosphorus removal process. At the same time, under aerobic conditions, organic nitrogen is converted into ammonia nitrogen by ammonifying microorganisms, and then ammonia nitrogen is converted into nitrate nitrogen by nitrifying bacteria. Because there is a biofilm hanging in the pool, nitrate nitrogen enters the inner membrane of the biofilm, and under the action of denitrifying bacteria, a part of the nitrate nitrogen is converted into nitrogen gas, and the remaining nitrified liquid is returned to the anoxic pool; the biofilm and the activated sludge jointly denitrify and remove phosphorus, thereby improving the removal effect.

[0022] The water inlet of the filter tank 5 is also provided with a baffle 15, and the setting method thereof is the same as that of the anoxic tank; the filter assembly 13 in the filter tank 5 is a canvas, and the water outlet of the filter tank 5 is provided with an outlet pipe 8. The sewage treated by the biological contact oxidation tank 4 enters from the water inlet at the top of the tank body, is filtered through the canvas, and the mud and water are completely separated, and the supernatant is directly discharged from the outlet pipe 8 to meet the standards, and the bottom sludge is partially returned to the biological rotary tank 1 through the sludge discharge pipe 161, and the remaining sludge is discharged through the sludge discharge pipe 162.

[0023] When the above-mentioned sewage treatment system is used to treat rural sewage, the specific process flow can be as follows:

[0024] S1, biological rotary pool: daily rural sewage production is 150-200m 3 , sewage with COD content of 50-400 mg / L, ammonia nitrogen content of 35-70 mg / L, total nitrogen content of 40-85 mg / L, and total phosphorus content of 2-9 mg / L is divided into the first part and the second part in a ratio of 1:1. The first part of the water flows into the biological turntable pool filled with activated sludge from the first water inlet pipe. The immersion rate of the disc is 40%, the motor speed is 4-6 r / min, and the return pump is turned on at the same time. The sewage treated in step S3 is returned, and the return ratio is 100%-400%. After the rotation of the biological turntable, the returned sewage and the untreated sewage are completely mixed. The rotating turntable stirs the sludge at the bottom of the pool to carry out nitrification reaction. The hydraulic retention time of the sewage is 8 hours, and the returned sludge is passed into the front end to supplement the biomass of the turntable.

[0025] S2, anoxic tank: the second part of rural sewage and the sewage treated by S1 enter from the upper water inlet of the tank body at a ratio of 1:1. At the same time, the stirring device and the reflux liquid switch are turned on. The stirring time is the same as the HRT time, which is 0.5-3h. The return ratio of sewage from S4 is 100%-400%. The nitrate nitrogen in the mixed sewage undergoes denitrification reaction through the action of denitrifying bacteria. The treated sewage flows out from the upper part of the tank body to complete the denitrification process.

[0026] S3, anaerobic tank: the sewage treated by S2 enters from the water inlet at the top of the tank body. Under anaerobic conditions, through anaerobic hydrolysis / fermentation, under the action of polyphosphate bacteria, organic matter is converted into acetic acid, etc., releasing inorganic phosphate into the sewage. The hydraulic retention time is 1 to 4 hours. The treated sewage flows out from the top of the tank body. The sewage return ratio from step S4 is 100% to 400%, and part of the sewage is returned to step S1;

[0027] S4, biological contact oxidation tank: the sewage treated by S3 enters from the water inlet on the upper part of the tank body, and the aeration device is turned on at the same time, with an aeration flow rate of 4-6L / min. Under the action of polyphosphate bacteria, the excessive phosphorus in the water is absorbed, and the sewage and phosphorus are separated, thereby removing a large amount of phosphorus and completing the phosphorus removal process. At the same time, the biofilm also ammonifies the nitrogen-containing organic matter that has not been degraded in the previous process, and then converts the ammonia nitrogen into nitrate nitrogen, and finally refluxes to the S2 step, with a reflux ratio of 100% to 400%, and the treated sewage flows out from the upper part of the tank body;

[0028] S5, canvas filter tank: The sewage treated by S4 enters from the water inlet on the upper part of the tank body, and is filtered through canvas to completely separate the mud and water. The supernatant is directly discharged in compliance with the standards, and part of the lower sludge flows back to the S1 step, and the remaining sludge is discharged.

[0029] The above descriptions are merely embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the protection scope of the present invention.

Claims

1. A system suitable for treating rural sewage, characterized in that: The system comprises a biological rotary disk pool (1), an anoxic pool (2), an anaerobic pool (3), a biological contact oxidation pool (4) and a filter pool (5) which are connected in sequence. The biological rotary disk pool (1) is provided with a biological rotary disk (9), the anoxic pool (2) and the anaerobic pool (3) are both provided with a stirring device (17), the biological contact oxidation pool (4) is provided with a composite filler (12), and the filter pool (5) is provided with a filtering component (13); a first mixed liquid reflux pipe is provided between the biological rotary disk pool (1) and the anaerobic pool (3). (10), a second mixed liquor return pipe (11) is provided between the biological contact oxidation tank (4) and the anoxic tank (2), and a mud discharge device (16) is provided at the bottom of the filter tank (5); the first mixed liquor return pipe (10) and the second mixed liquor return pipe (11) are both connected to a return pump; the water inlet ends of the anoxic tank (2), the anaerobic tank (3), the biological contact oxidation tank (4) and the filter tank (5) are all provided with a baffle (15), the top of the baffle (15) is higher than the liquid surface and the bottom has a gap with the bottom of the tank.

2. The system for treating rural sewage according to claim 1, characterized in that: The system comprises a first water inlet pipe (6) and a second water inlet pipe (7), wherein the first water inlet pipe (6) is arranged at the bottom end of the biological rotary pool (1), and the water outlet of the second water inlet pipe (7) is located in the anoxic pool (2).

3. The system for treating rural sewage according to claim 1, characterized in that: An aeration pipe (14) is provided at the bottom of the biological contact oxidation pond (4).

4. The system for treating rural sewage according to claim 1, characterized in that: The sludge discharge device (16) comprises a first sludge discharge pipe (161) and a second sludge discharge pipe (162), wherein the first sludge discharge pipe is connected to the bottom of the biological rotary tank (1), and the first sludge discharge pipe (161) and the second sludge discharge pipe (162) are both connected to sludge pumps.

5. The system for treating rural sewage according to claim 1, characterized in that: The filtering component (13) is canvas.

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