A high-efficiency intelligent backwashing system for upflow biofilter

Abstract

The invention discloses a high-efficiency intelligent backwashing system for an upward flow biofilter. The invention can completely solve the problems of the existing upward flow biofilter, such as the excessive backwashing intensity affecting the removal efficiency of pollutants, the frequent backwashing of the filter due to insufficient backwashing intensity or too short backwashing time, and even the problems of the biofilter material being compacted and the filter plate flipping due to insufficient backwashing. The invention can completely solve the impact of the existing upward flow biofilter on the front-end pretreatment unit and the additional increase in operating costs caused by the frequent backwashing of the upward flow biofilter. The high-efficiency intelligent backwashing system can realize early warning, reduce the uncertain factors of human intervention, and strangle the overall compaction of the filter in advance, thereby ensuring the normal operation of the filter. The invention has great promotion and application value in the field of upward flow biofilter technology.

Description

Technical Field

[0001] The invention relates to the field of sewage treatment, and in particular to a high-efficiency intelligent backwashing system for an upward flow biological filter. Background Art

[0002] It is an irresistible trend to improve the discharge standard of urban sewage treatment. Biofilm sewage treatment technology has been widely studied and applied. Among them, aerated biological filter tanks are widely used in the field of sewage deep treatment due to their advantages of small footprint, low operating costs, small infrastructure investment, high processing load, convenient operation and management, and good treatment effect. The upward flow biological filter tank has no sludge discharge system and adopts cyclic operation. It needs to be backwashed regularly. A complete cycle is from the beginning of filtration to the end of backwashing. The specific process is as follows: the pretreated sewage enters the filter layer upward from the bottom of the filter tank through the long-handled filter head installed on the filter plate. The lower part of the filter layer can be provided with an aeration system for aeration as needed. As the operation process proceeds, the biomass attached to the surface of the filter material increases due to metabolism. At the same time, the suspended matter intercepted in the water by the filter layer continues to increase. When it accumulates to a certain amount, the filter tank must be backwashed to remove the excessive microbial film and suspended matter in the filter bed and restore its normal processing capacity. The backwashing of the biological filter tank generally adopts the "lowering water level + air-water combined method". The backwashing water is the treated water that meets the standards, and the backwashing air comes from the blower. The aged biofilm is separated from the trapped suspended matter and the filter material by backwashing, and discharged from the filter tank with the backwashing drainage. The backwashing drainage flows into the drainage wastewater pool by gravity, and the sewage in the wastewater pool is lifted to the front-end pretreatment unit by a water pump and enters the plant system for secondary treatment.

[0003] The current upward flow biofilter backwashing method of "lowering water level + combined air and water method" solves the problem of filter blockage in the water and air distribution system of the biofilter through the lowering water level operation, but there are still many problems in the operation of the biofilter: ① In order to prevent the filter material from being compacted and affecting the normal operation of the filter, the backwashing intensity is increased. Once the backwashing intensity is too large, it is easy to reduce the efficiency of the filter to remove pollutants, and it is impossible to ensure that the effluent water quality is stable and meets the discharge standards; ② Insufficient backwashing intensity or too short backwashing time setting can easily lead to frequent backwashing of the filter, and even cause the filter material of the biofilter to be compacted due to insufficient backwashing. In severe cases, the filter may even flip over, causing serious production accidents; ③ Frequent backwashing, the backwashing wastewater is lifted to the front-end pretreatment unit by the lifting pump and enters the system for secondary treatment, which will increase the processing load of the pretreatment unit, and at the same time, it will increase the cost of secondary treatment of backwashing wastewater, resulting in high overall operating costs, which does not meet the principle of economic and stable operation. Therefore, it is urgent to develop an efficient and intelligent backwashing system. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned problems and to provide a high-efficiency intelligent backwashing system for an upward flow biological filter, so as to overcome the operational difficulties currently encountered. The specific contents are as follows: the high-efficiency intelligent backwashing system is composed of an upward flow biological filter, a pressure sensor, a PLC system, a suspended matter detector, and a liquid level meter; the upward flow biological filter is composed of a water distribution chamber, a supporting layer, a ceramsite filter material reaction layer, a clean water area, an outlet channel, and an outlet pipe from bottom to top, a suspended matter detector is installed in the clean water area, a long-handled filter head, a filter plate and a pressure sensor are installed in the water distribution chamber, and above them are a supporting layer and a ceramsite filter material reaction layer; the pressure sensor is located below the filter plate and is used to measure the pressure of the long-handled filter head. The pressure value between the water surface of the clear water area above the filter layer, and the head loss recorded by the PLC program = the pressure value head of the normal water flow in the upward flow biological filter - the pressure value head of the upward flow biological filter when it is full of water and not flowing; the suspended matter detector is located in the clear water area; the PLC system contains pressure change trend analysis software for monitoring pressure trend changes; the upward flow biological filter is a denitrification biological filter, the supporting layer thickness is 300mm, and the height of the clear water area is 1.2-1.5m; the steps of the automatic backwashing system are as follows:

[0005] (1) Normal backwash:

[0006] ① Normal backwash start point: the pressure monitored by the pressure sensor and the threshold point of the suspended solids concentration in the clear water area monitored by the suspended solids detector are reached. When one of the two is reached, the normal backwash procedure is started; the prerequisite for backwashing is one of the following: 1) After 5 hours of normal water inflow and outflow after backwashing, when the suspended solids concentration monitored by the suspended solids detector exceeds 20mg / L; 2) When the filtration rate is 8-12m / h, the head loss monitored by the pressure sensor exceeds 0.4 times the filter material layer thickness threshold (unit m); when the filtration rate is 12-15m / h, the head loss monitored by the pressure sensor exceeds 0.5 times the filter material layer thickness threshold (unit m); when the filtration rate is 15-20m / h, the head loss monitored by the pressure sensor exceeds 0.55 times the filter material layer thickness threshold (unit m);

[0007] ②Normal backwashing procedure: 1) Backwashing by lowering the water level: First open the control valve of the backwashing drainage pipe. At this time, the water level in the biofilter begins to decrease. When the biofilter is operating normally, the free liquid surface drops to the surface of the filter material. Close the control valve on the backwashing drainage pipe. Through the backwashing effect, the fibrous substances and biofilm on the surface of the long-handled filter head are washed and discharged to prevent the long-handled filter head from being blocked. 2) Then perform air washing: Open the control valve on the backwashing air inlet pipe, start the backwashing blower, and allow the backwashing air to enter the upward flow biofilter from the backwashing air inlet pipe to start air washing. , so that the filter material is loose, the air washing intensity is 14-25L / min·s, and the air washing time is 2-5min; 3) Air-water combined backwashing: open the control valve on the backwashing water inlet pipe, and then use the treated effluent to enter the filter tank from the backwashing water inlet pipe, start the air-water combined backwashing, and discharge the aged biofilm and the trapped suspended matter out of the pool. The air-water combined backwashing time is 5-8min; 4) Water rinsing: turn off the backwashing blower, and then close the control valve of the backwashing air inlet pipe, and perform water rinsing alone, the water rinsing intensity is 4-6L / min·s, and the water rinsing time is 5-15min;

[0008] (3) Forced backwash:

[0009] ①Forced backwash starting point:

[0010] The forced backwashing procedure is started when one of the following priority conditions is met: after backwashing, when the head loss (unit m) monitored by the pressure sensor increases to the backwashing threshold condition in step (1) 2) and the time required is less than 5 hours; 2) after each consecutive backwashing, when the head loss (unit m) monitored by the pressure sensor increases to the backwashing threshold condition in step (1) 2) and the difference in the shortening of the adjacent backwashing cycles monitored before and after exceeds 1 hour;

[0011] ② Forced backwash procedure: The forced backwash sequence is the same as the normal backwash procedure ②, and the water level reduction backwash method is adopted. The difference is that by increasing the intensity of forced backwash, the local compaction phenomenon in the filter tank is completely solved in advance, avoiding frequent backwashing of the filter tank due to insufficient backwashing intensity or too short backwashing time, or even the compaction of the filter material in the biological filter tank due to insufficient backwashing, and the overall compaction of the filter tank is nipped in the bud in the bud to ensure the normal operation of the filter tank. Reasonable forced backwashing intensity can avoid frequent backwashing of the filter tank due to insufficient backwashing intensity or too short backwashing time, or even the compaction of the filter material in the biological filter tank due to insufficient backwashing; the difference is: the air washing intensity is 25~30L / min·s, and the water rinsing intensity is 8~10L / min·s.

[0012] The filter material layer has a thickness of 1.5 to 4.0 m and a diameter of 3 to 9 mm; the clean water area has a thickness of 1.2 to 1.5 m, and the supporting layer has a thickness of 0.2 to 0.3 m.

[0013] The backwashing is performed by adopting the "water level reduction + air-water combined method". When backwashing is performed by reducing the water level, the cross-sectional flow velocity in the filter rod at the lower end of each filter head is ensured to be not less than 0.2 m / s.

[0014] During the process of lowering the water level, the height to which the free liquid surface of the upward flow biofilter drops during normal operation can be controlled by a level gauge installed on the top of the biofilter.

[0015] The backwashing system comprises a backwashing blower, a backwashing water pump, and water distribution and air distribution pipelines; the backwashing blower, the backwashing water pump, and the regulating valve are connected to a program automatic control system.

[0016] The present invention is used for an upward flow biological filter, which completely solves the problems that the removal efficiency of pollutants in the existing upward flow biological filter is affected by excessive backwashing intensity, the filter is frequently backwashed due to insufficient backwashing intensity or the backwashing time is set too short, and even the filter material of the biological filter is compacted and the filter plate flips due to insufficient backwashing. It completely solves the impact of frequent backwashing of the existing upward flow biological filter on the front-end pretreatment unit and the additional increase in operating costs caused by it. Through the efficient and intelligent backwashing system, early warning is achieved, the uncertain factors of human intervention are reduced, the overall compaction of the filter is strangled in the cradle in advance, and the normal operation of the filter is guaranteed. It has great promotion and application value in the field of upward flow biological filter technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic structural diagram of a high-efficiency intelligent backwashing system for an upward flow biofilter.

[0018] Among them: 1. Upward flow biological filter, 2. Water distribution chamber, 3. Support layer, 4. Expanded clay filter material reaction layer, 5. Clean water area, 6. Outlet channel, 7. Long-handled filter head, 8. Filter plate, 9. Pressure sensor, 10. Suspended matter detector, 11. Liquid level gauge, 12. Backwash outlet pipe control valve, 13. Backwash outlet pipe, 14. Lowering water level drainage pipe control valve, 15 Lowering water level drainage pipe, 16. Backwash water pump, 17. Backwash inlet pipe, 18. Backwash inlet pipe control valve, 19. Backwash blower, 20. Backwash air inlet pipe, 21. Backwash air inlet pipe control valve, 22. Outlet pipe, 23. PLC system, 24. Control cable. DETAILED DESCRIPTION

[0019] The following is combined with Figure 1 The present invention is further described:

[0020] The high-efficiency intelligent backwashing system is composed of an upward flow biological filter (1), a pressure sensor (9), a PLC system (23), a suspended matter detector (10), and a liquid level meter (11); the upward flow biological filter (1) is composed of a water distribution chamber (2), a supporting layer (3), a ceramsite filter material reaction layer (4), a clean water area (5), an outlet channel (6), and an outlet pipe (22) from bottom to top; a suspended matter detector (10) is installed in the clean water area (5); a long-handled filter head (7), a filter plate (8), and a pressure sensor (9) are installed in the water distribution chamber (2), and the supporting layer (3) and the ceramsite filter material reaction layer (4) are located above the supporting layer (3) and the ceramsite filter material reaction layer (4); the pressure sensor (9) is located on the filter plate (8) is used to measure the pressure value between the long-handled filter head (7) and the water surface of the clear water area (5) above the filter material layer (4), and the head loss recorded by the PLC program = the pressure value head of the normal water flow of the upward flow biological filter (1) - the pressure value head of the upward flow biological filter (1) when it is full of water and not flowing; the suspended matter detector (10) is located in the clear water area (5); the PLC system (23) contains pressure change trend analysis software for monitoring pressure trend changes; the upward flow biological filter (1) is a denitrification biological filter, the supporting layer (3) is 300mm thick, and the clear water area (5) is 1.2 to 1.5m high; the steps of the automatic backwashing system are as follows:

[0021] (1) Normal backwash:

[0022] ① Normal backwashing start point: the pressure monitored by the pressure sensor (9) and the threshold value of the suspended matter concentration in the clean water area (5) monitored by the suspended matter detector (10) are reached. When one of the two is reached, the normal backwashing procedure is started; the prerequisite for backwashing is one of the following: 1) after 5 hours of normal water inflow and outflow after backwashing, when the suspended matter concentration monitored by the suspended matter detector (10) exceeds 20 mg / L; 2) when the filtration rate is 8 to 12 m / h, the head loss monitored by the pressure sensor (9) exceeds 0.4 times the filter material layer thickness threshold (unit m); when the filtration rate is 12 to 15 m / h, the head loss monitored by the pressure sensor (9) exceeds 0.5 times the filter material layer thickness threshold (unit m); when the filtration rate is 15 to 20 m / h, the head loss monitored by the pressure sensor (9) exceeds 0.55 times the filter material layer thickness threshold (unit m);

[0023] ② Normal backwashing procedure: 1) Backwashing by lowering the water level: first open the control valve (14) of the backwashing drainage pipe (15) to lower the water level in the biofilter (1). At this time, the water level in the biofilter (1) begins to decrease. When the free liquid surface of the biofilter (1) is normally operated, it drops to the surface of the filter material. Then close the control valve (14) on the backwashing drainage pipe (15). Through the backwashing action, the fibrous material and biofilm on the surface of the long-handled filter head (7) are washed and discharged to prevent the long-handled filter head (7) from being blocked. 2) Perform air washing again: open the control valve (21) on the backwashing air inlet pipe (20), start the backwashing blower (19), and allow the backwashing air to enter the upward flow from the backwashing air inlet pipe (20). The biofilter (1) starts air washing to loosen the filter material, the air washing intensity is 14 to 25 L / min·s, and the air washing time is 2 to 5 minutes; 3) air-water combined backwashing: open the control valve (18) on the backwashing water inlet pipe (17), and then use the treated effluent to enter the filter from the backwashing water inlet pipe (17), start air-water combined backwashing, discharge the aged biofilm and the trapped suspended matter out of the pool, and the air-water combined backwashing time is 5 to 8 minutes; 4) water rinsing: turn off the backwashing blower (19), and then close the control valve (21) of the backwashing air inlet pipe (20), and perform water rinsing alone, the water rinsing intensity is 4 to 6 L / min·s, and the water rinsing time is 5 to 15 minutes;

[0024] (3) Forced backwash:

[0025] ①Forced backwash starting point:

[0026] The forced backwashing procedure is started when one of the following priority conditions is met: after backwashing, when the head loss (unit m) monitored by the pressure sensor (9) increases to the backwashing threshold condition in step (1) 2) and the time required is less than 5 hours; 2) after each consecutive backwashing, when the head loss (unit m) monitored by the pressure sensor (9) increases to the backwashing threshold condition in step (1) 2) and the difference in shortening of the adjacent backwashing cycles monitored before and after exceeds 1 hour;

[0027] ② Forced backwash procedure: The forced backwash sequence is the same as the normal backwash procedure ②, and the water level reduction backwash method is adopted. The difference is that by increasing the intensity of the forced backwash, the local compaction phenomenon in the filter tank is completely solved in advance, avoiding the frequent backwashing of the filter tank due to insufficient backwashing intensity or too short backwashing time, or even the compaction of the filter material in the biological filter tank (1) due to insufficient backwashing. The overall compaction of the filter tank is nipped in the bud in the bud to ensure the normal operation of the filter tank. Reasonable forced backwashing intensity can avoid the frequent backwashing of the filter tank due to insufficient backwashing intensity or too short backwashing time, or even the compaction of the filter material in the biological filter tank (1) due to insufficient backwashing. The difference is: the air washing intensity is 25~30L / min·s, and the water rinsing intensity is 8~10L / min·s.

[0028] The filter material layer (4) has a thickness of 1.5 to 4.0 m and a diameter of 3 to 9 mm; the clear water area is 1.2 to 1.5 m, and the supporting layer is 0.2 to 0.3 m.

[0029] The backwashing is performed by adopting the "water level reduction + air-water combined method". When backwashing is performed by reducing the water level, the cross-sectional flow velocity in the filter rod at the lower end of each filter head is ensured to be not less than 0.2 m / s.

[0030] During the process of lowering the water level, the height to which the free liquid surface of the upward flow biofilter (1) drops during normal operation can be controlled by a liquid level meter (11) installed on the top of the biofilter.

[0031] The backwashing system comprises a backwashing blower (19), a backwashing water pump (16), and water distribution and air distribution pipelines; the backwashing blower (19), the backwashing water pump (16), and the regulating valves (21, 18) are connected to a program automatic control system.

[0032] Embodiment 1:

[0033] A municipal sewage treatment plant in Anhui Province has a treatment flow rate of 40,000m3 / d and adopts the "high-efficiency sedimentation tank + pre-denitrification biological filter" process. Through the effective control of this high-efficiency intelligent backwashing system, while ensuring the stable operation of the filter, the annual backwashing wastewater volume has been reduced by 20% compared with before, saving nearly 1 million yuan in direct costs.

[0034] Embodiment 2:

[0035] A municipal sewage treatment plant in Nanjing, Jiangsu Province, with a treatment flow of 200,000 m3 / d, adopts the "high-efficiency sedimentation tank + pre-denitrification biological filter" process. Through the effective control of this high-efficiency intelligent backwashing system, the operating pressure of the denitrification filter is always maintained at 0.05 MPa. The filter has been backwashed with uniform water and air distribution for three consecutive years, and the backwash water volume has been reduced by 18% compared with before, saving nearly 4 million yuan in annual operating costs.

[0036] The present invention is used for an upward flow biological filter, which completely solves the problems that the removal efficiency of pollutants in the existing upward flow biological filter is affected by excessive backwashing intensity, the filter is frequently backwashed due to insufficient backwashing intensity or the backwashing time is set too short, and even the filter material of the biological filter is compacted and the filter plate flips due to insufficient backwashing. It completely solves the impact of frequent backwashing of the existing upward flow biological filter on the front-end pretreatment unit and the additional increase in operating costs caused by it. Through the efficient and intelligent backwashing system, early warning is achieved, the uncertain factors of human intervention are reduced, the overall compaction of the filter is strangled in the cradle in advance, and the normal operation of the filter is guaranteed. It has great promotion and application value in the field of upward flow biological filter technology.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A flushing method using an efficient intelligent backwashing system of an upward flow biofilter, characterized in that: The high-efficiency intelligent backwashing system is composed of an upward flow biofilter, a pressure sensor, a PLC system, a suspended matter detector, and a liquid level meter; the upward flow biofilter is composed of a water distribution chamber, a supporting layer, a ceramsite filter material reaction layer, a clean water area, a water outlet channel, and a water outlet pipe from bottom to top, a suspended matter detector is installed in the clean water area, a long-handled filter head, a filter plate and a pressure sensor are installed in the water distribution chamber, and a supporting layer and a ceramsite filter material reaction layer are installed above; the pressure sensor is located below the filter plate and is used to measure the pressure between the long-handled filter head and the filter material layer. The pressure value between the water surfaces in the upper clear water area, and the head loss recorded by the PLC program at the same time = the pressure value head of the normal water flow in the upward flow biological filter - the pressure value head of the upward flow biological filter when it is full of water and not flowing; the suspended matter detector is located in the clear water area; the PLC system contains pressure change trend analysis software for monitoring pressure trend changes; the upward flow biological filter is a denitrification biological filter, the supporting layer thickness is 300mm, and the height of the clear water area is 1.2-1.5m; the steps of the automatic backwashing system are as follows: (1) Normal backwash: ① Normal backwash start point: the pressure monitored by the pressure sensor and the threshold point of the suspended solids concentration in the clear water area monitored by the suspended solids detector are reached. When one of the two is reached, the normal backwash procedure is started; the prerequisite for backwashing is one of the following: 1) After 5 hours of normal water inflow and outflow after backwashing, when the suspended solids concentration monitored by the suspended solids detector exceeds 20mg / L; 2) When the filtration rate is 8-12m / h, the head loss monitored by the pressure sensor exceeds 0.4 times the filter material layer thickness threshold (unit m); when the filtration rate is 12-15m / h, the head loss monitored by the pressure sensor exceeds 0.5 times the filter material layer thickness threshold (unit m); when the filtration rate is 15-20m / h, the head loss monitored by the pressure sensor exceeds 0.55 times the filter material layer thickness threshold (unit m); ②Normal backwashing procedure: 1) Backwashing by lowering the water level: First open the control valve of the backwashing drainage pipe. At this time, the water level in the biofilter begins to decrease. When the biofilter is operating normally, the free liquid surface drops to the surface of the filter material. Close the control valve on the backwashing drainage pipe. Through the backwashing effect, the fibrous substances and biofilm on the surface of the long-handled filter head are washed and discharged to prevent the long-handled filter head from being blocked. 2) Then perform air washing: Open the control valve on the backwashing air inlet pipe, start the backwashing blower, and allow the backwashing air to enter the upward flow biofilter from the backwashing air inlet pipe to start air washing. , so that the filter material is loose, the air washing intensity is 14~25L / (㎡·s), and the air washing time is 2~5min; 3) Air-water combined backwashing: open the control valve on the backwashing water inlet pipe, and then use the treated effluent to enter the filter tank from the backwashing water inlet pipe, start the air-water combined backwashing, and discharge the aged biofilm and the retained suspended matter out of the pool. The air-water combined backwashing time is 5~8min; 4) Water rinsing: turn off the backwashing blower, and then close the control valve of the backwashing air inlet pipe, and perform water rinsing alone, the water rinsing intensity is 4~6L / (㎡·s), and the water rinsing time is 5~15min; (2) Forced backwash: ①Forced backwash starting point: When one of the following priority conditions is met, the forced backwashing procedure is started: 1) After backwashing, when the head loss (unit m) monitored by the pressure sensor increases to the backwashing threshold condition in step (1) ①2), and the time required is less than 5 hours; 2) After each consecutive backwashing, when the head loss (unit m) monitored by the pressure sensor increases to the backwashing threshold condition in step (1) ①2), and the difference in the shortening of the adjacent backwashing cycles monitored before and after exceeds 1 hour; ② Forced backwash procedure: The forced backwash sequence is the same as the normal backwash procedure ②, and the water level reduction backwash method is adopted. The difference is that the intensity of the forced backwash is increased; the difference is: the air washing intensity is 25~30L / (㎡·s), and the water rinsing intensity is 8~10L / (㎡·s).

2. The flushing method of a high-efficiency intelligent backwashing system using an upward flow biofilter according to claim 1, characterized in that: The filter material layer has a thickness of 1.5 to 4.0 m.

3. The flushing method of a high-efficiency intelligent backwashing system using an upward flow biofilter according to claim 1, characterized in that: When backwashing with lowered water level, ensure that the cross-sectional flow velocity in the filter rod at the lower end of each filter head is not less than 0.2m / s.

4. The flushing method of a high-efficiency intelligent backwashing system using an upward flow biofilter according to claim 1, characterized in that: During the process of lowering the water level, the height to which the free liquid surface of the upward flow biofilter drops during normal operation is controlled by a level gauge installed on the top of the biofilter.

5. The flushing method of a high-efficiency intelligent backwashing system using an upward flow biofilter according to claim 1, characterized in that: The backwashing system comprises a backwashing blower, a backwashing water pump, and water distribution and air distribution pipelines; the backwashing blower, the backwashing water pump, and the regulating valve are connected to a program automatic control system.

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