A control system for oxygenation of water droplets in an upward flow denitrification biofilter

Abstract

The invention discloses a control system for oxygenating waterfalls in an upward-flow denitrifying biofilter. The invention can completely solve the problem that oxygenating waterfalls in a water distribution channel of a denitrifying biofilter seriously inhibits denitrification and limits the denitrification capacity of the system; completely solve the problem that the dissolved oxygen in the inlet water of the denitrifying biofilter is too high due to oxygenating waterfalls, which wastes a large amount of external denitrifying carbon sources and causes an additional sharp increase in operating costs; effectively reduce the problem of excessive backwash water volume in the existing biofilter, ensure that the effluent is economically stable and meets standards, and has stronger impact resistance, thereby having great value for promotion and application.

Description

Technical Field

[0001] The invention relates to a sewage treatment process, in particular to a control system for oxygenating a waterfall in an upward-flow denitrification biological filter. Background Art

[0002] At present, the improvement of urban sewage treatment discharge standards is an irresistible trend, and biofilm sewage treatment technology has been widely studied and applied. Among them, aerated biological filters are widely used in the field of deep sewage treatment due to their advantages of small footprint, low operating costs, small infrastructure investment, high treatment load, convenient operation and management, and good treatment effect. In this process, the upward flow denitrification biofilter has a good denitrification effect on nitrogen in sewage. At present, there are many processes for deep denitrification treatment of sewage, among which the deep denitrification treatment technology of denitrification biofilter has shown good development prospects and market value, but there are still many problems in the existing technology, which are mainly manifested as follows.

[0003] The denitrifying biological filter is used for deep denitrification treatment of sewage, and adopts the "channel + pipeline" method for water distribution. During the channel water distribution process, the oxygenation phenomenon accompanied by waterfalls is very serious, resulting in excessive dissolved oxygen in the denitrifying biological filter inlet water. There are the following defects: ① Denitrifying bacteria are heterotrophic anaerobic bacteria, which need to grow and reproduce under anoxic / anaerobic conditions. High concentrations of dissolved oxygen will seriously inhibit denitrification (in biofilm systems, dissolved oxygen is controlled below 1.0 mg / L), which seriously limits the system's denitrification capacity; ② Removing 1 kg BOD requires 0.733 kg O2. When the dissolved oxygen in the denitrification biofilter influent is too high, a large amount of external denitrification carbon source will be wasted; taking a sewage treatment plant with a treatment scale of 500,000 tons / day as an example, the oxygenation of the influent waterfall of the denitrification denitrification biofilter increases by 4 to 6 mg / L, and the annual carbon source (sodium acetate) cost increases by nearly 6 to 8 million yuan due to the problem of dissolved oxygen in the waterfall; ③ Because the influent contains a large amount of dissolved oxygen, under the action of organic carbon source, due to the short era cycle of aerobic heterotrophic bacteria, the aerobic heterotrophic bacteria at the bottom of the filter layer will increase in large quantities, resulting in a rapid increase in filter bed resistance, resulting in a shortened backwash cycle, frequent backwashing, and a sharp increase in backwash water volume.

[0004] Therefore, it is very necessary to develop a deep denitrification control system that aims to control the dissolved oxygen concentration of the denitrifying biological filter inlet, evenly distribute water, and stably obtain economical and stable sewage treatment. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problems and provide a control system for oxygenation of waterfalls in upward flow denitrification biological filters to overcome the difficulties currently encountered. The specific contents are as follows: the upward flow denitrification biological filter is composed of a horizontal water passage, a water distribution channel, a liquid level meter, a water distribution electric valve, a water distribution chamber, a long-handled filter head, a filter plate, a supporting layer, a filter material reaction layer, a clean water area, a backwash drainage channel, a water outlet channel, a water outlet pipe, a backwash water system, a backwash gas system, and a PLC system; the horizontal water passage is connected to the water distribution channel of the upward flow denitrification biological filter to control the uniform water inflow of multiple groups of upward flow denitrification biological filters; the liquid level meter in the water distribution channel is respectively connected to the water distribution electric valve and the PLC system to measure, feedback, adjust and control, and then feedback the waterfall level difference; the control system process of oxygenation of waterfalls in the upward flow denitrification biological filter is as follows:

[0006] (1) Water drop level difference measurement and parameter setting: The difference value of the level gauge in the water distribution channel and the opening degree signal of the water distribution electric valve are connected to the PLC system; the level gauge is used to measure the level difference between the water head on the weir of the horizontal water passage and the water surface in the water distribution channel, that is, the water drop level difference of the level gauge, and the water drop level difference value is 0.1 to 0.3 m;

[0007] (2) Constant adjustment of the drop head difference: 1) After the backwash is completed, the aging biofilm and the suspended solids trapped by the filter layer are backwashed out of the pool by the backwash system, resulting in the head loss of the filter layer in the upward flow denitrification biofilter being minimized (minimum resistance), resulting in the maximum drop head difference between the water head on the weir of the horizontal water passage and the water surface of the water distribution channel. The PLC system is used to reduce the opening degree of the water distribution electric valve, reduce the water head loss of the water distribution electric valve, maintain a constant water level, and prevent drop oxygenation and air entrainment. 1) The phenomenon of water flow is prevented from occurring, and uniform water distribution is achieved synchronously; 2) As the time after backwashing increases, the biofilm of the upward flow denitrification biological filter continues to grow, and the amount of suspended solids intercepted increases. The PLC system increases the opening degree of the water distribution electric valve, reduces the head loss, maintains a constant water level, reduces the head loss of the water distribution electric valve, achieves dynamic control of the constant water level, prevents the occurrence of waterfall oxygenation and air entrainment oxygenation, and achieves uniform water distribution synchronously; 3) During the backwashing period, the opening degree of the water distribution electric valve of the upward flow denitrification biological filter is 0, which is a closed state.

[0008] The opening degree of the water distribution electric valve is 0-100%, and the opening degree of the water distribution electric valve is dynamically controlled by the drop head difference value monitored by the PLC.

[0009] The upward flow denitrification biological filter tank is composed of a water distribution chamber, a supporting layer, a filter material reaction layer, a clean water area, an outlet channel, and an outlet pipe from bottom to top. A long-handled filter head and a filter plate are installed in the water distribution chamber, and a supporting layer and a filter material reaction layer are arranged above them.

[0010] The adjustable electric valve of the normal water inlet pipeline is provided with three controls of opening, stopping and closing, and can display the specific opening percentage of the valve and upload it to the PLC system.

[0011] The filter material can be ceramsite filter material, quartz filter material, volcanic rock filter material, or shale filter material.

[0012] The thickness of the filter material reaction layer is 1.8-4.0 m.

[0013] The transverse water passage can evenly distribute water to at least two groups of water distribution channels.

[0014] The present invention thoroughly solves the problem that the existing denitrification biofilter water distribution channel waterfall oxygenation seriously inhibits denitrification and limits the system's denitrification capacity; it thoroughly solves the problem that the denitrification biofilter causes excessive dissolved oxygen in the inlet water due to waterfall oxygenation, which wastes a large amount of external denitrification carbon source and causes an additional sharp increase in operating costs; it effectively reduces the problem of excessive backwash water volume in the existing biofilter, ensures that the effluent economy stably meets the standards, has stronger impact resistance, and has great promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a schematic structural diagram of a control system for oxygenating a waterfall in an upward flow denitrification biological filter.

[0016] Among them: 1. Upward flow denitrification biofilter, 2. Horizontal water flow channel, 3. Water distribution channel, 4. Liquid level meter, 5. Normal water inlet pipe, 6. Water distribution electric valve, 7. Water distribution chamber, 8. Support layer, 9. Filter material reaction layer, 10. Clean water area, 11. Backwash drainage channel, 12. Outlet channel, 13. Long-handled filter head, 14. Filter plate, 15. Outlet pipe, 16. Backwash water system, 17. Backwash air system, 18. Control cable, 19. PLC system. DETAILED DESCRIPTION

[0017] The following is combined with Figure 1 The present invention is further described:

[0018] A control system for oxygenating water in an upward flow denitrification biofilter (1), characterized in that the upward flow denitrification biofilter (1) comprises a transverse water passage (2), a water distribution channel (3), a liquid level meter (4), a water distribution electric valve (6), a water distribution chamber (7), a long-handled filter head (13), a filter plate (14), a supporting layer (8), a filter material reaction layer (9), a clean water area (10), a backwash drainage channel (11), a water outlet channel (12), a water outlet pipe (15), a backwash water system (16), a backwashing system (17), a backwashing system (18), a backwashing system (19), a backwashing system (20), a backwashing system (21), a backwashing system (22), a backwashing system (23), a backwashing system (24), a backwashing system (25), a backwashing system (26), a backwashing system (27), a backwashing system (28), a backwashing system (29), a backwashing system (30), a backwashing system (31), a backwashing system (32), a backwashing system (33), a backwashing system (34), a backwashing system (35), a backwashing system (36), a backwashing system (37), a backwashing system (38), a backwashing system (39), a backwashing system (40), a backwashing system (41), a backwashing system (42), a backwashing system (43), a backwashing system (44), a backwashing system (45), a backwashing system (46), a backwashing system (47), a backwashing system (48), a backwashing system (49), a backwashing system (49), a backwashing system (49), a backwashing system (4 The invention is composed of a gas system (17) and a PLC system (19); the horizontal water passage (2) is connected to the water distribution channel (3) of the upward flow denitrification biological filter (1) to control the uniform water inflow of multiple groups of upward flow denitrification biological filters (1); the liquid level meter (4) in the water distribution channel (3) is respectively connected to the water distribution electric valve (6) and the PLC system (19) to measure, feedback, adjust and control, and then feedback the drop head difference; the control system process of the drop oxygenation of the upward flow denitrification biological filter (1) is as follows:

[0019] (1) Water drop level difference measurement and parameter setting: The difference value of the liquid level meter (4) in the water distribution channel (3) and the opening degree signal of the water distribution electric valve (6) are connected to the PLC system (19); the liquid level meter (4) is used to measure the level difference between the water head on the weir of the horizontal water passage (2) and the water surface in the water distribution channel (3), that is, the water drop level difference of the liquid level meter (4), and the water drop level difference value is 0.1 to 0.3 m;

[0020] (2) Constant adjustment of the drop head difference: 1) After the backwashing is completed, the upflow denitrification biofilter tank is backwashed out of the tank by the backwashing system because the aged biofilm and the suspended solids trapped by the filter layer are backwashed out of the tank, resulting in the head loss of the filter layer (9) in the upflow denitrification biofilter tank (1) being reduced to a minimum (minimum resistance), resulting in the drop head difference between the water head on the weir of the horizontal water passage (2) and the water surface of the water distribution channel (3) being maximized. The PLC system (19) is used to reduce the opening degree of the water distribution electric valve (6), increase the head loss of the water distribution electric valve (6), maintain a constant water level, and prevent the drop from being oxygenated and aerated. The phenomenon of oxygenation occurs, and uniform water distribution is achieved simultaneously; 2) as the time after backwashing increases, the biofilm of the upward flow denitrification biological filter (1) continues to grow, and the amount of suspended solids intercepted increases. The PLC system (19) increases the opening degree of the water distribution electric valve (6), reduces the head loss, maintains a constant water level, increases the head loss of the water distribution electric valve (6), realizes dynamic control of the constant water level, prevents the occurrence of drop oxygenation and air entrainment oxygenation, and achieves uniform water distribution simultaneously; 3) during the backwashing period, the opening degree of the water distribution electric valve (6) of the upward flow denitrification biological filter (1) is 0, which is a closed state.

[0021] The opening degree of the water distribution electric valve (6) is 0-100%, and the opening degree of the water distribution electric valve (6) is dynamically controlled by the drop head difference value monitored by the PLC;

[0022] The upward flow denitrification biological filter (1) is composed of a water distribution chamber (7), a supporting layer (8), a filter material reaction layer (9), a clean water area (10), a water outlet channel (12), and a water outlet pipe (15) from bottom to top. A long-handled filter head (13) and a filter plate (14) are installed in the water distribution chamber (7), and the supporting layer (8) and the filter material reaction layer (9) are arranged above them.

[0023] The adjustable electric valve (6) of the normal water inlet pipe (5) is provided with three control functions: opening, stopping and closing, and can display the specific opening percentage of the valve and upload it to the PLC system (19).

[0024] The filter material can be ceramsite filter material, quartz filter material, volcanic rock filter material, or shale filter material.

[0025] The thickness of the filter material reaction layer is 1.8-4.0 m.

[0026] The transverse water passage (2) can evenly distribute water to at least two groups of water distribution channels (3).

[0027] Embodiment 1:

[0028] A municipal sewage treatment plant in Hebei Province, with a treatment flow of 40,000m 3 / d, the original core process was the "oxidation ditch + secondary sedimentation tank" process, and the denitrifying biological filter was used for upgrading and transformation to remove TN. The effluent from the secondary sedimentation tank was lifted twice by a lifting pump to the denitrification distribution channel. The DO value of the distribution channel was 1.0 mg / L, and the DO value from the distribution channel to the single denitrification inlet pipe was 8 mg / L. After adopting the waterfall oxygenation control system, the DO value from the distribution channel to the single denitrification inlet pipe dropped to 0.9 mg / L. There was basically no waste of carbon source due to waterfall oxygenation, which greatly saved the operating cost.

[0029] Embodiment 2:

[0030] A sewage treatment plant in a chemical park in Jiangsu Province, with a treatment flow of 20,000m 3 / d, the original main process was the "hydrolysis acidification + AAO + secondary sedimentation tank" process, the secondary treatment effluent entered the denitrification biofilter process to improve the TN index, the secondary sedimentation tank effluent went to the denitrification biofilter distribution channel, the DO value of the distribution channel was 1.5mg / L, and the DO value from the distribution channel to the single denitrification water inlet pipe was 7.9mg / L. After adopting the waterfall oxygenation control system, the DO value from the distribution channel to the single denitrification water inlet pipe dropped to 0.5mg / L, and there was basically no waste of carbon source due to waterfall oxygenation, thus saving 600,000 yuan in carbon source cost each year.

[0031] The present invention thoroughly solves the problem that the existing denitrification biofilter water distribution channel waterfall oxygenation seriously inhibits denitrification and limits the system's denitrification capacity; it thoroughly solves the problem that the denitrification biofilter causes excessive dissolved oxygen in the inlet water due to waterfall oxygenation, which wastes a large amount of external denitrification carbon source and causes an additional sharp increase in operating costs; it effectively reduces the problem of excessive backwash water volume in the existing biofilter, ensures that the effluent economy stably meets the standards, has stronger impact resistance, and has great promotion and application value.

[0032] 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 control system for oxygenation of waterfall in an upward flow denitrification biofilter, characterized in that: The upward flow denitrification biofilter is composed of a horizontal water passage, a water distribution channel, a liquid level meter, a water distribution electric valve, a water distribution chamber, a long-handled filter head, a filter plate, a supporting layer, a filter material reaction layer, a clean water area, a backwash drainage channel, a water outlet channel, a water outlet pipe, a backwash water system, a backwash gas system, and a PLC system; the horizontal water passage is connected to the water distribution channel of the upward flow denitrification biofilter to control the uniform water inflow of multiple groups of upward flow denitrification biofilters; the liquid level meter in the water distribution channel is respectively connected to the water distribution electric valve and the PLC system to measure, feedback, adjust and control, and then feedback the drop head difference; the control system process of the drop oxygenation of the upward flow denitrification biofilter is as follows: (1) Water drop level difference measurement and parameter setting: The difference value of the level gauge in the water distribution channel and the opening degree signal of the water distribution electric valve are connected to the PLC system; the level gauge is used to measure the level difference between the water head on the weir of the horizontal water passage and the water surface in the water distribution channel, that is, the water drop level difference of the level gauge, and the water drop level difference value is 0.1 to 0.3 m; (2) Constant adjustment of the drop head difference: 1) After the backwash is completed, the aging biofilm and the suspended solids trapped by the filter layer are backwashed out of the pool by the backwash system, resulting in the head loss of the filter layer in the upward flow denitrification biofilter being minimized, resulting in the maximum drop head difference between the water head on the weir of the horizontal water passage and the water surface of the water distribution channel. The PLC system is used to reduce the opening degree of the water distribution electric valve, increase the water head loss of the water distribution electric valve, maintain a constant water level, and prevent the phenomenon of drop oxygenation and air entrainment oxygenation. 1) As the time after backwashing increases, the biofilm of the upward flow denitrification biofilter continues to grow, and the amount of suspended solids intercepted increases. The PLC system increases the opening of the water distribution electric valve, reduces the head loss, maintains a constant water level, reduces the head loss of the water distribution electric valve, realizes dynamic control of the constant water level, prevents the occurrence of water drop oxygenation and air entrainment oxygenation, and realizes uniform water distribution simultaneously; 2) During the backwashing period, the opening of the water distribution electric valve of the upward flow denitrification biofilter is 0, which is a closed state; The opening degree of the water distribution electric valve is 0-100%, and the opening degree of the water distribution electric valve is dynamically controlled by the drop head difference value monitored by the PLC; The upward flow denitrification biofilter is composed of a water distribution chamber, a supporting layer, a filter material reaction layer, a clean water area, a water outlet channel, and a water outlet pipe from bottom to top. A long-handled filter head and a filter plate are installed in the water distribution chamber, and a supporting layer and a filter material reaction layer are located on the water distribution chamber. The transverse water passage evenly distributes water to at least two groups of water distribution channels.

2. A control system for upward flow denitrification biological filter waterfall oxygenation according to claim 1, characterized in that: The water distribution electric valve of the normal water inlet pipeline has three control functions: open, stop and close. It can also display the specific opening percentage of the valve and upload it to the PLC system.

3. A control system for upward flow denitrification biological filter waterfall oxygenation according to claim 1, characterized in that: The filter material is ceramsite filter material, quartz filter material, volcanic rock filter material, and shale filter material.

4. A control system for waterfall oxygenation in an upflow denitrification biofilter according to claim 1, characterized in that: The thickness of the filter material reaction layer is 1.8-4.0 m.

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