A sewage treatment method and system for enhancing the biochemical performance of return activated sludge

Abstract

The invention discloses a sewage treatment method and system for strengthening the biochemical performance of return activated sludge, including a sewage treatment process, at least including treatment in an inlet structure and a primary sedimentation tank, a biochemical reaction tank, a secondary sedimentation tank, and a return sludge strengthening tank and a granular sludge selector on the return sludge line, the sewage outlet of the biochemical reaction tank is connected to the sewage inlet of the secondary sedimentation tank, part of the mud and water mixture precipitated in the secondary sedimentation tank enters the return sludge strengthening tank, and the sewage outlet of the return sludge strengthening tank is connected to the sewage inlet of the granular sludge selector. The invention can significantly increase the proportion of larger granular sludge in the biochemical reaction tank, improve the granulation level of activated sludge, significantly improve sewage treatment efficiency and shock load resistance, is conducive to improving the peak rainy season and low-temperature sewage treatment capacity in winter, is also conducive to odor control, sludge reduction and reduction of land occupation, investment and agent addition, and is suitable for the new construction, expansion and capacity expansion and upgrading of sewage treatment plants of various sizes.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment and water pollution control, and in particular to a sewage treatment method and system for enhancing the biochemical performance of return activated sludge. Background Art

[0002] At present, we are at the historical intersection of the battle against pollution and the construction of a beautiful China. The continuous reduction of major pollutants and the continuous improvement of the ecological environment remain important tasks for our future work. The ecological restoration of water environment quality and the creation of more fishable and swimmable water bodies have put forward higher technical requirements for sewage treatment and water pollution control.

[0003] In the current field of sewage treatment technology, the conventional activated sludge method is one of the most widely used technologies, but it has certain shortcomings and weaknesses in terms of increased water volume in the rainy season, changes in water quality, and lower water temperature in winter. In order to solve the above problems, the current technical means are usually to increase the scale of the project, superimpose process units, add chemical agents, add microbial attachment carriers, etc., which leads to more and more complex processes, higher operating costs, greater energy consumption, and more and more residual sludge. Summary of the invention

[0004] The purpose of the present invention is to provide a sewage treatment method and system for enhancing the biochemical performance of return activated sludge, so as to solve the technical, efficiency and cost problems existing in the sewage treatment process proposed in the above background technology and overcome the shortcomings of existing technologies and measures.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A sewage treatment method for enhancing the biochemical performance of return activated sludge includes a sewage treatment process, which at least includes treatment in an inlet structure and a primary sedimentation tank, a biochemical reaction tank, a secondary sedimentation tank, and a return sludge enhancement tank and a granular sludge selector on a return sludge line, wherein the sewage outlets of the inlet structure and the primary sedimentation tank are connected to the sewage inlet of the biochemical reaction tank, the sewage outlet of the biochemical reaction tank is connected to the sewage inlet of the secondary sedimentation tank, the supernatant in the secondary sedimentation tank is discharged into a subsequent water treatment process, part of the mud-water mixture precipitated in the secondary sedimentation tank enters the return sludge enhancement tank, the sewage outlet of the return sludge enhancement tank is connected to the sewage inlet of the granular sludge selector, and the outflow of the granular sludge selector is returned to the aforementioned sewage treatment process.

[0007] Furthermore, the return sludge strengthening tank adopts a periodic reciprocating aeration method of gradually increasing the aeration volume and then gradually reducing the aeration volume, and its minimum dissolved oxygen content is 0.2 mg / L and the maximum is 3 mg / L.

[0008] Furthermore, the hydraulic retention time of the return sludge enhancement tank is 5-36h.

[0009] Furthermore, in order to improve the denitrification and phosphorus removal performance and deodorization function of the activated sludge in the biochemical reaction tank, a bacillus inoculum solution is continuously added to the return sludge strengthening tank, and the addition amount is 0.5-2% of the return sludge amount. The bacillus inoculum solution is prepared by 0.5-1 kg of bacillus microcapsule powder with an effective ingredient content of not less than 10 billion CFU / g and 1 cubic meter of biochemical reaction tank influent, and is continuously aerated for 1-3 days, and the dissolved oxygen is maintained between 1-2 mg / L during aeration.

[0010] Furthermore, in order to improve the activated sludge precipitation performance and water quality shock load resistance of the biochemical reaction tank, a mixed solution of magnesium hydroxide and calcium hydroxide is intermittently added to the return sludge strengthening tank, with an addition amount of 20-200 mg / L (based on the amount of return sludge), and the mass ratio of magnesium hydroxide to calcium hydroxide is 1:2-1:10.

[0011] Furthermore, in order to select granular sludge with high density, high strength, stable structure and good sedimentation performance to return to the biochemical reaction tank, the granular sludge selector on the return sludge line is mainly one of the granular separation devices such as a short-duration inclined tube sedimentation tank, a short-duration inclined plate sedimentation tank, a hydrocyclone separator, and an upward flow fluidized bed.

[0012] Furthermore, the outflow of the granular sludge selector enters the water inlet structure and the water inlet end of the primary sedimentation tank and the front end of the biochemical reaction tank respectively.

[0013] Furthermore, the outflow of the granular sludge selector is divided into three parts. The first part enters the water inlet structure and the water inlet end of the primary sedimentation tank, the second part enters the front end of the anaerobic section of the biochemical reaction tank, and the third part enters the front end of the aerobic section of the biochemical reaction tank.

[0014] Furthermore, the upper overflow of the granular sludge selector is discharged into the excess sludge line and enters the subsequent sludge treatment process together with the excess sludge.

[0015] And, a sewage treatment system for enhancing the biochemical performance of return activated sludge, the sewage treatment system includes an inlet structure and a primary sedimentation tank, a biochemical reaction tank, a secondary sedimentation tank, and a return sludge enhancement tank and a granular sludge selector on the return sludge line, the sewage outlets of the inlet structure and the primary sedimentation tank are connected to the sewage inlet of the biochemical reaction tank, the sewage outlet of the biochemical reaction tank is connected to the sewage inlet of the secondary sedimentation tank, the supernatant in the secondary sedimentation tank is discharged into the subsequent water treatment process, part of the mud and water mixture precipitated in the secondary sedimentation tank enters the return sludge enhancement tank, the sewage outlet of the return sludge enhancement tank is connected to the sewage inlet of the granular sludge selector, and the outflow of the granular sludge selector returns to the aforementioned sewage treatment process.

[0016] Preferably, an upward flow fluidized bed is used as a granular sludge selector, and its surface hydraulic load is 5-20m 3 / m 2 ·h.

[0017] For typical A 2 / O biochemical treatment process, the outflow of the granular sludge selector is divided into three parts. The first part enters the water inlet of the sewage treatment plant, accounting for 2%-10% of the outflow, and is mainly used to enhance the reduction of the generation and emission of odor-causing gases in the sewage treatment process; the second part enters the front end of the biochemical reaction tank, accounting for 70%-88% of the outflow, and is mainly used to enhance biological denitrification and phosphorus removal; the third part enters the front end of the aerobic section of the biochemical reaction tank, accounting for 10%-20% of the outflow, and is mainly used to enhance the degradation of organic matter and nitrification.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least:

[0019] 1. It can significantly increase the proportion of larger granular sludge in the biochemical reaction tank, that is, without adding carrier fillers, it can increase the concentration of activated sludge in the biochemical reaction tank, thereby improving the sewage treatment efficiency, thus reducing the land area of ​​the new sewage treatment plant and saving investment.

[0020] 2. It can improve the impact load resistance of existing sewage treatment plants. On the premise of ensuring that the effluent water quality meets the standards, it can accept combined sewage in the rainy season and improve the peak treatment capacity of existing sewage treatment plants in the rainy season. It can also show good treatment effects on low-temperature sewage in the northern winter.

[0021] 3. It has a good effect in reducing the odor of sewage treatment plants. It can remove and inhibit malodorous gases such as hydrogen sulfide, ammonia, organic acids, etc. from the source. It is also beneficial to reduce sludge and improve the dewatering properties of sludge.

[0022] 4. Applicable to the new construction, expansion, renovation and upgrading projects of traditional activated sludge process and A / A / O, A / O, SBR, MBR, oxidation ditch and other processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a schematic flow chart of a sewage treatment method for enhancing the biochemical performance of return activated sludge.

[0024] In the figure: 1. Water inlet structure and primary sedimentation tank; 2. Biochemical reaction tank; 21. Anaerobic section; 22. Anoxic section; 23. Aerobic section; 3. Secondary sedimentation tank; 4. Return sludge enhancement tank; 5. Granular sludge selector. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, a sewage treatment method for enhancing the biochemical performance of return activated sludge includes a sewage treatment process, wherein the sewage treatment process at least includes treatment in an inlet structure and a primary sedimentation tank 1, a biochemical reaction tank 2, a secondary sedimentation tank 3, and a return sludge enhancement tank 4 and a granular sludge selector 5 on the return sludge line, wherein the sewage outlet of the inlet structure and the primary sedimentation tank 1 is connected to the sewage inlet of the biochemical reaction tank 2, and in order to improve the denitrification and dephosphorization performance and deodorization function of the activated sludge in the biochemical reaction tank 2, a bacillus inoculation solution is continuously added to the return sludge enhancement tank 4, and the addition amount is 0.5-2% of the return sludge amount, and the bacillus inoculation solution is prepared by 0.5-1 kg of bacillus microcapsule powder with an effective ingredient content of not less than 10 billion CFU / g and 1 cubic meter of biochemical reaction tank inlet water, and continuously. The aeration is carried out for 1-3 days, and the dissolved oxygen is maintained between 1-2 mg / L during aeration. The sewage outlet of the biochemical reaction tank 2 is connected to the sewage inlet of the secondary sedimentation tank 3. The supernatant in the secondary sedimentation tank 3 is discharged into the subsequent water treatment process. Part of the mud-water mixture precipitated in the secondary sedimentation tank 3 enters the return sludge enhancement tank 4. The sewage outlet of the return sludge enhancement tank 4 is connected to the sewage inlet of the granular sludge selector 5. The outflow of the granular sludge selector (5) is returned to the aforementioned sewage treatment process. In order to improve the activated sludge precipitation performance and water quality shock load resistance function of the biochemical reaction tank 2, a mixed solution of magnesium hydroxide and calcium hydroxide is intermittently added to the return sludge enhancement tank 4, and the addition amount is 20-200 mg / L (based on the amount of return sludge), and the mass ratio of magnesium hydroxide to calcium hydroxide is 1:2-1:10.

[0027] The biochemical reaction tank 2 is composed of an anaerobic section 21, an anoxic section 22, and an aerobic section 23, which are arranged in series, and the outflow of the granular sludge selector 5 enters the water inlet structure and the water inlet end of the primary sedimentation tank 1, the front end of the anaerobic section 21 of the biochemical reaction tank 2, and the front end of the aerobic section 23 of the biochemical reaction tank 2. Furthermore, as Figure 1 As shown, the upper overflow of the granular sludge selector is discharged into the residual sludge line (shown by the dotted line) and enters the subsequent sludge treatment process together with the residual sludge.

[0028] On the other hand, the present invention provides a sewage treatment system for enhancing the biochemical performance of return activated sludge, which is used to implement the above-mentioned sewage treatment method for enhancing the biochemical performance of return activated sludge. The sewage treatment system includes an inlet structure and a primary sedimentation tank (1), a biochemical reaction tank (2), a secondary sedimentation tank (3), and a return sludge enhancement tank (4) and a granular sludge selector (5) on the return sludge line. The relationship and function of each part are as described above.

[0029] Example 1

[0030] Considering the current situation of a town with an area of ​​15,000 m 3 / d sewage treatment plant as an example, the effluent water quality standard is Class A, SBR biochemical treatment and coagulation sedimentation deep treatment process is used, industrial wastewater accounts for about 30%-50%, and the sludge return ratio is about 40%-50%. In recent years, with the industrial development and population increase in the town, the amount of sewage in the town has continued to increase. The sewage treatment plant is at full capacity, and there are still about 6,000 m 3 / d of sewage needs to be treated. After many attempts to overload the sewage treatment plant, the effluent quality is still difficult to meet the standard. The sewage treatment method of the present invention that enhances the biochemical performance of the return activated sludge is selected to build a new group of 1000m 3 Return sludge enhancement tank 4 and 50m 3 The granular sludge selector 5 is connected to the return sludge pipeline in turn. The hydraulic retention time of the return sludge enhancement tank 4 is 5 hours, and the Bacillus inoculation solution is continuously added. The upward flow fluidized bed is selected as the granular sludge selector 5, and its surface hydraulic load is 10m 3 / m 2 h. The outflow of the granular sludge selector 5 is divided into two parts. The first part enters the water inlet of the sewage treatment plant, accounting for 5% of the outflow, and the second part enters the front end of the biochemical reaction tank 2, accounting for 95% of the outflow. After 16 days of commissioning, the treatment capacity of the sewage treatment plant has been increased to 22,000 m 3 / d, the activated sludge concentration in biochemical reaction tank 2 increased to 5500mg / L, the number of sludge particles with a diameter of about 0.5mm-0.7mm accounted for more than 50%, and no flocculant was needed in the coagulation and sedimentation deep treatment stage. The effluent quality was better than Class A standard, with ammonia nitrogen at about 1.5mg / L and total phosphorus at about 0.3mg / L.

[0031] Example 2

[0032] A new 50,000 m2 development zone in a certain city 3 / d sewage treatment plant as an example, the sewage treatment method for enhancing the biochemical performance of return activated sludge of the present invention is selected, and a return sludge enhancement tank 4 and a granular sludge selector 5 are added to the return sludge line. The activated sludge concentration of the designed biochemical reaction tank 2 is increased from the original 3500mg / L to 7000mg / L, and the biochemical tank capacity is reduced by half compared with the original design. After the sewage treatment plant was built and put into operation, the effluent water quality stably reached "quasi-IV class", and the odor concentration at the plant boundary also stably reached the standard without opening the biological filter deodorization system.

[0033] Example 3

[0034] Considering the current situation of a city with a land area of ​​100,000 m 3 / d sewage treatment plant as an example, the sewage plant adopts A 2 / O biochemical treatment and coagulation sedimentation deep treatment process, due to the water environment quality requirements of the receiving water body, the effluent water quality standard needs to be upgraded from Class A to "quasi-Class IV". At the same time, in order to reduce the overflow volume and overflow frequency of overflow pollution in the rainy season, it is necessary to increase the peak treatment capacity of 50,000 m in the rainy season. 3 / d. The sewage treatment method of the present invention for enhancing the biochemical performance of the return activated sludge was selected, and two new groups of 3500m 3 Return sludge enhancement tank 4 and 200m 3 The granular sludge selector 5 is connected to the return sludge pipeline in turn. The hydraulic retention time of the return sludge enhancement tank 4 is 6 hours, and the Bacillus inoculation solution is continuously added. In the rainy season, a mixed solution of magnesium hydroxide and calcium hydroxide is added. The upward flow fluidized bed is selected as the granular sludge selector 5, and its surface hydraulic load is 8m 3 / m 2 h. The outflow of the granular sludge selector 5 is divided into three parts. The first part enters the water inlet of the sewage treatment plant, accounting for 2% of the outflow, the second part enters the front end of the anaerobic section 21 of the biochemical reaction tank, accounting for 78% of the outflow, and the third part enters the front end of the aerobic section 23 of the biochemical reaction tank, accounting for 20% of the outflow. After 25 days of commissioning and operation, the effluent water quality is better than "quasi-IV class", the amount of residual sludge is reduced by 20-30%, and the peak treatment capacity in the rainy season has stably reached 150,000 m 3 / d.

[0035] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A sewage treatment method for enhancing the biochemical performance of return activated sludge, characterized in that: The invention comprises a sewage treatment process, wherein the sewage treatment process at least comprises treatment in an inlet structure and a primary sedimentation tank (1), a biochemical reaction tank (2), a secondary sedimentation tank (3), and a return sludge enhancement tank (4) and a granular sludge selector (5) on the return sludge line, wherein the sewage outlet of the inlet structure and the primary sedimentation tank (1) is connected to the sewage outlet of the biochemical reaction tank (2), the sewage outlet of the biochemical reaction tank (2) is connected to the sewage outlet of the secondary sedimentation tank (3), the supernatant in the secondary sedimentation tank (3) is discharged into a subsequent water treatment process, part of the mud-water mixture precipitated in the secondary sedimentation tank (3) enters the return sludge enhancement tank (4), the sewage outlet of the return sludge enhancement tank (4) is connected to the sewage inlet of the granular sludge selector (5), and the outflow of the granular sludge selector (5) is returned to the aforementioned sewage treatment process, and the return sludge enhancement tank (4) adopts a periodic method of gradually increasing the aeration amount and then gradually reducing the aeration amount. The granular sludge selector (5) is a double aeration method, and its minimum dissolved oxygen content is 0.2 mg / L and its maximum value is 3 mg / L. The outflow of the granular sludge selector (5) enters the water inlet structure and the water inlet end of the primary sedimentation tank (1) and the front end of the biochemical reaction tank (2) respectively. The outflow of the granular sludge selector (5) is divided into three parts. The first part enters the water inlet structure and the water inlet end of the primary sedimentation tank (1), and the second part enters the front end of the anaerobic section (21) of the biochemical reaction tank (2). The first part enters the front end of the aerobic section (23) of the biochemical reaction tank (2), and the third part enters the front end of the aerobic section (23) of the biochemical reaction tank (2). For the A / A / O biochemical treatment process, the outflow of the granular sludge selector is divided into three parts. The first part enters the water inlet end of the water inlet structure and the primary sedimentation tank (1), accounting for 2%-10% of the outflow; the second part enters the front end of the biochemical reaction tank, accounting for 70%-88% of the outflow; the third part enters the front end of the aerobic section of the biochemical reaction tank, accounting for 10%-20% of the outflow.

2. The sewage treatment method for enhancing the biochemical performance of return activated sludge according to claim 1, characterized in that: The hydraulic retention time of the return sludge strengthening tank (4) is 5-36 hours.

3. The sewage treatment method for enhancing the biochemical performance of return activated sludge according to claim 1, characterized in that: The Bacillus inoculum solution is continuously added to the return sludge enhancement tank (4).

4. The sewage treatment method for enhancing the biochemical performance of return activated sludge according to claim 1, characterized in that: A mixed solution of magnesium hydroxide and calcium hydroxide is intermittently added to the return sludge strengthening tank (4), wherein the mass ratio of magnesium hydroxide to calcium hydroxide is 1:2-1:

10.

5. The sewage treatment method for enhancing the biochemical performance of return activated sludge according to claim 1, characterized in that: The granular sludge selector (5) on the return sludge line is one of granular separation devices such as a short-duration inclined tube sedimentation tank, a short-duration inclined plate sedimentation tank, a hydrocyclone separator, an upward flow fluidized bed, etc.

6. The sewage treatment method for enhancing the biochemical performance of return activated sludge according to claim 1, characterized in that: The upper overflow of the granular sludge selector (5) is discharged into the excess sludge line and enters the subsequent sludge treatment process together with the excess sludge.

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