Aerobic pool tail end in-situ optimization energy-saving system for sewage treatment

Abstract

The invention discloses an aerobic tank tail end in-situ optimization energy-saving system for sewage treatment, which comprises an aerobic zone tail end gallery, bottom aeration is cancelled in the gallery, a plurality of groups of surface aeration systems arranged at equal intervals are arranged in the gallery, an ammonia nitrogen on-line monitor and a nitrate nitrogen on-line monitor are arranged at the water inlet end of the gallery, and the ammonia nitrogen on-line monitor and the nitrate nitrogen on-line monitor are arranged in the gallery. The on-line monitoring instrument and the surface aeration system are connected with the PLC control end. The method has the beneficial effects that the tail end of the aerobic tank is transformed into a self-adaptive dissolved oxygen regulation and control region based on ammonia nitrogen content feedback, so that when the ammonia nitrogen content is relatively low, the PLC control end automatically instructs the surface aeration system to stop aeration, and meanwhile, the carbon source feeding system is timely started to supplement a carbon source according to the fed nitrate nitrogen content; the invention relates to in-situ transformation, and has the advantages of low investment cost, simple control structure, capability of enhancing denitrification, reduction of aeration energy input, reduction of operation cost and obvious energy-saving effect.

Description

Technical Field

[0001] The invention relates to the technical field of urban domestic sewage treatment, in particular to an in-situ optimization energy-saving system at the end of an aerobic tank for sewage treatment. Background Art

[0002] Since the 1980s, a large number of urban sewage treatment plants have been built and put into operation in my country, and the water ecological environment has been greatly improved. With the increasingly stringent environmental protection regulations and the proposal of the dual-carbon strategy, the heat of cost reduction, efficiency improvement, energy conservation and emission reduction continues. Many old sewage treatment plants have gradually reached the period of needing capacity expansion and upgrading. Equipment upgrading, process optimization, and integration of automatic control technology have become the technical route for reducing energy consumption and high-quality development in the current sewage treatment industry.

[0003] When sewage treatment plants were first built, the water quality was relatively simple and the treatment technology was not yet perfect. The planning and design only focused on the removal of some simple pollutants such as organic matter and ammonia nitrogen. At the same time, in order to cope with uncertain factors such as water inflow fluctuations and equipment failures, a certain redundancy factor was set. 2 Taking the / O process as an example, in general, the volume ratio of the anaerobic tank, anoxic tank and aerobic tank is 1:2:4, in order to leave sufficient retention time for each system to achieve the highest treatment efficiency. However, many sewage treatment plants are currently facing the problem of low organic matter concentration in the incoming water, which is far below the design value. The organic matter is first consumed in the anaerobic and anoxic zones due to dilution, adsorption, biological utilization and other processes, and there is little left when entering the aerobic zone. In this case, autotrophic nitrifying bacteria quickly take the advantage, nitrification is accelerated, and the ammonia nitrogen content decreases rapidly.

[0004] For example, the first-phase biological treatment system of a sewage treatment plant adopts the UCT process. A certain period of stable operation is selected, and the concentrations of key pollutants at the inlet and outlet of the terminal corridor of the aerobic zone are continuously monitored for 3 months. The average values ​​are as follows in Table 1:

[0005] Inlet (mg / L) Outlet (mg / L) COD 14.34 13.68 Ammonia nitrogen 0.17 0.19 Nitrate nitrogen 10.13 10.26 Orthophosphate 0.94 0.92

[0006] Table 1 Key pollutant concentrations at the inlet and outlet of the end gallery of the aerobic pool

[0007] The monitoring results show that there is almost no obvious change in the pollutant concentration at the inlet and outlet of the terminal corridor of the aerobic pool. Therefore, it can be considered that before the end of the aerobic zone, the degradation of organic matter and nitrification have been completed. Continuing aeration not only wastes power energy, but also causes excessive aeration, which will make the sludge growth mainly based on endogenous respiration, accelerate sludge aging, reduce sludge activity, and have a poor polyphosphate effect. Summary of the invention

[0008] The object of the present invention is to provide an in-situ optimization and energy-saving system for the end of an aerobic tank in sewage treatment, aiming at the disadvantages in the prior art that due to the lack of carbon source in the aerobic zone, autotrophic nitrifying bacteria quickly become the dominant flora, resulting in the premature completion of the nitrification reaction (usually the ammonia nitrogen degradation is completed at the front end of the aerobic zone), the loss of functional targets in the terminal aeration stage, and the waste of energy consumption and deterioration of sludge performance caused by excessive aeration.

[0009] The object of the present invention is achieved through the following technical solutions: An in-situ optimization and energy-saving system for the end of an aerobic tank in sewage treatment includes a corridor located at the end of the aerobic zone. An ammonia nitrogen on-line monitor for real-time monitoring of the ammonia nitrogen content in the influent is installed at the inlet end of the corridor. Multiple groups of surface aeration systems arranged at equal distances are provided in the corridor. The ammonia nitrogen on-line monitor and the surface aeration system are both connected to the PLC control terminal;

[0010] A nitrate nitrogen on-line detector for monitoring the nitrate nitrogen content in the influent is installed at the inlet end of the corridor. A carbon source dosing system connected to the PLC control terminal is installed at the inlet end of the corridor;

[0011] The carbon source dosing system includes a feed pipe. The feed end of the feed pipe is connected to the discharge end of a metering pump. The feed end of the metering pump is connected to an external carbon source storage device. The metering pump is connected to the PLC control terminal;

[0012] The corridor, the ammonia nitrogen on-line monitor, the nitrate nitrogen on-line detector, the surface aeration system, the carbon source dosing system, and the PLC control terminal form an adaptive dissolved oxygen regulation area;

[0013] By setting up the corridor, the ammonia nitrogen on-line monitor, the nitrate nitrogen on-line detector, the surface aeration system, the carbon source dosing system, and the PLC control terminal in cooperation, the end of the aerobic tank is transformed into an adaptive dissolved oxygen regulation area based on the feedback of ammonia nitrogen content. When the ammonia nitrogen content is low, it can automatically command the surface aeration system to stop aeration, providing favorable conditions for sludge denitrification. At the same time, starting the carbon source dosing system to supplement the carbon source can significantly accelerate the denitrification rate, not only strengthening nitrogen removal, but also reducing the input of aeration energy, lowering the operating cost, and having a significant energy-saving effect.

[0014] A further technical solution is that the surface aeration system includes a rotating shaft. Multiple groups of rotating brushes arranged in a circumferential array are installed on the rotating shaft. One end of the rotating shaft is connected to the power output end of a motor. By setting a certain depth of the rotating brush according to the actual operating conditions, the oxygenation efficiency and energy consumption can be balanced, and at the same time, the effect of promoting water flow can be ensured.

[0015] A further technical solution is that the feed pipe is arranged in the middle of the corridor. Multiple groups of feed ports arranged at equal distances are installed on the feed pipe. Setting multiple groups of feed ports arranged at equal distances can effectively discharge the carbon source evenly into the corridor, making the carbon source distribution in the corridor uniform.

[0016] A further technical solution is that multiple groups of submersible thrusters are installed in the corridor at equal distances. All the multiple groups of submersible thrusters are installed in the middle of the corridor. The multiple groups of submersible thrusters and the multiple groups of surface aeration systems are arranged alternately. Arranging the submersible thrusters and the surface aeration systems alternately can stably push the water flow and at the same time has a certain mixing effect, so that the carbon source added to the corridor is evenly dispersed in the corridor.

[0017] A further technical solution is that the feed pipe is arranged at the water inlet end of the corridor, and the first group of submersible thrusters in the corridor is arranged at the front end of the feed pipe. By arranging the first group of submersible thrusters in the corridor at the front end of the feed pipe, the carbon source put into the feed pipe can be quickly dispersed under the mixing action of the submersible thrusters, improving the uniformity of the carbon source distribution.

[0018] A further technical solution is that the PLC control terminal is responsible for controlling the metering pump to add the carbon source to the corridor. The PLC control terminal receives the online nitrate nitrogen content data monitored by the nitrate nitrogen on-line detector and adjusts the carbon source addition amount T of the carbon source addition system in real time. The calculation formula for the carbon source addition amount T is:

[0019] T = 1000 * Q(C 监测 - C 目标 )n / y

[0020] Wherein, T is the carbon source addition amount, L / h;

[0021] Q is the sewage flow rate, m 3 / h;

[0022] C 监测 is the nitrate nitrogen concentration fed back by the nitrate nitrogen on-line monitor, mg / L;

[0023] C 目标 is the set nitrate nitrogen concentration control value, set to 12 mg / L;

[0024] n is the COD equivalent required to reduce 1 g of nitrate nitrogen, set to 5 gCOD / gN;

[0025] y is the COD equivalent of the carbon source used, 300000 mg / L;

[0026] Setting the PLC control terminal to receive the online nitrate nitrogen content data monitored by the nitrate nitrogen on-line detector and adjust the carbon source addition amount T of the carbon source addition system in real time can ensure the denitrification efficiency of the sewage. At the same time, avoiding excessive carbon source, the remaining carbon source organic matter will cause the increase of effluent COD, increasing the treatment cost and may also cause secondary pollution. It can not only ensure enough carbon source for denitrification, but also avoid excessive amount causing secondary pollution and cost waste.

[0027] The present invention has the following advantages: The end of the aerobic tank is transformed into an adaptive dissolved oxygen regulation area based on the feedback of ammonia nitrogen content, enabling it to automatically command the surface aeration system to stop aeration when the ammonia nitrogen content is low, providing favorable conditions for sludge denitrification. At the same time, starting the carbon source dosing system to supplement the carbon source can significantly accelerate the denitrification rate, not only strengthening nitrogen removal, but also reducing the input of aeration energy, lowering the operating cost, and having a remarkable energy-saving effect. The PLC control terminal is set to receive the online nitrate nitrogen content data monitored by the nitrate nitrogen on-line detector to regulate the carbon source dosing amount T of the carbon source dosing system in real time, which can ensure the denitrification efficiency of the sewage. At the same time, avoiding excessive carbon source, the remaining carbon source organic matter will cause the increase of effluent COD, increasing the treatment cost and possibly causing secondary pollution. It can not only ensure sufficient carbon source for denitrification, but also avoid excessive amount causing secondary pollution and cost waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the front view schematic diagram of the overall structure of the present invention;

[0029] Figure 2 is the logic operation diagram of the PLC control terminal in the present invention;

[0030] Figure 3 is the side view schematic diagram of the sectional structure of the surface aeration system in the present invention;

[0031] Figure 4 is the side view schematic diagram of the structure of the carbon source dosing system in the present invention;

[0032] In the figure, 1, corridor; 2, ammonia nitrogen on-line monitor; 3, nitrate nitrogen on-line detector; 4, surface aeration system; 401, rotating shaft; 402, rotating brush; 403, motor; 5, carbon source dosing system; 501, feed pipe; 502, metering pump; 503, feed port; 6, submersible thruster. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0037] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] Embodiment: As Figures 1 - 4 shown, an in-situ optimization and energy-saving system at the end of an aerobic tank for sewage treatment includes a corridor 1. The corridor 1 is located at the end of the aerobic zone. An ammonia nitrogen on-line monitor 2 for real-time monitoring of the ammonia nitrogen content of the influent is installed at the inlet end of the corridor 1. The bottom aeration device in the corridor 1 is cancelled, and a plurality of surface aeration systems 4 arranged at equal distances are provided. The ammonia nitrogen on-line monitor 2 and the surface aeration system 4 are both connected to the PLC control terminal;

[0040] A nitrate nitrogen on-line detector 3 for monitoring the nitrate nitrogen content of the influent is installed at the inlet end of the corridor 1. A carbon source dosing system 5 connected to the PLC control terminal is installed at the inlet end of the corridor 1;

[0041] The carbon source dosing system 5 includes a feed pipe 501. The feed end of the feed pipe 501 is connected to the discharge end of a metering pump 502. The feed end of the metering pump 502 is connected to an external carbon source storage device. The metering pump 502 is connected to the PLC control terminal;

[0042] The corridor 1, the on-line ammonia nitrogen monitor 2, the on-line nitrate nitrogen detector 3, the surface aeration system 4, the carbon source dosing system 5 and the PLC control terminal form an adaptive dissolved oxygen regulation area;

[0043] By setting the corridor 1, the on-line ammonia nitrogen monitor 2, the on-line nitrate nitrogen detector 3, the surface aeration system 4, the carbon source dosing system 5 and the PLC control terminal to cooperate, the end of the aerobic tank is transformed into an adaptive dissolved oxygen regulation area based on the feedback of ammonia nitrogen content. When the ammonia nitrogen content is low, the PLC control terminal automatically commands the surface aeration system 4 to stop aeration, and at the same time, according to the nitrate nitrogen content feedback by the on-line nitrate nitrogen detector 3, the carbon source dosing system 5 is started in a timely manner to supplement the carbon source, providing favorable conditions for sludge denitrification. The present invention relates to in-situ transformation, with low investment cost and simple control structure. It can not only strengthen nitrogen removal, but also reduce the input of aeration energy, lower the operating cost, and have remarkable energy-saving effect.

[0044] The surface aeration system 4 includes a rotating shaft 401, and a plurality of groups of rotating brushes 402 arranged in a circumferential array are installed on the rotating shaft 401. One end of the rotating shaft 401 is connected to the power output end of the motor 403. By setting a certain rotating brush depth according to the actual operating conditions, the oxygenation efficiency and energy consumption can be balanced, and at the same time, the effect of promoting water flow can be ensured.

[0045] The feed pipe 501 is arranged in the middle of the corridor 1, and a plurality of groups of feed ports 503 arranged in an equidistant array are installed on the feed pipe 501. Setting a plurality of groups of feed ports 503 arranged in an equidistant array can effectively discharge the carbon source evenly into the corridor 1, making the carbon source distribution in the corridor 1 uniform.

[0046] A plurality of groups of submersible propellers 6 are installed in the corridor 1 at equal distances. A plurality of groups of submersible propellers 6 are all installed in the middle of the corridor 1. The plurality of groups of submersible propellers 6 and the plurality of groups of surface aeration systems 4 are arranged alternately. Setting the submersible propellers 6 and the surface aeration systems 4 alternately can stably promote the water flow, and at the same time has a certain mixing effect, so that the carbon source added to the corridor 1 is evenly dispersed in the corridor 1.

[0047] The feed pipe 501 is arranged at the water inlet end of the corridor 1, and the first group of submersible propellers 6 in the corridor 1 is arranged at the front end of the feed pipe 501. By arranging the first group of submersible propellers 6 in the corridor 1 at the front end of the feed pipe 501, the carbon source discharged from the feed pipe 501 can be quickly dispersed under the mixing action of the submersible propellers 6, improving the uniformity of carbon source distribution.

[0048] The PLC control terminal is responsible for controlling the carbon source dosing amount of the metering pump 502 to the corridor 1. The PLC control terminal receives the on-line nitrate nitrogen content data monitored by the on-line nitrate nitrogen detector 3 and adjusts the carbon source dosing amount T of the carbon source dosing system 5 in real time. The calculation formula of the carbon source dosing amount T is:

[0049] T = 1000 * Q(C监测 -C 目标 )n / y

[0050] where T is the carbon source dosage, L / h;

[0051] Q is the sewage flow rate, m 3 / h;

[0052] C 监测 is the nitrate nitrogen concentration feedback by the on-line nitrate nitrogen monitor, mg / L;

[0053] C 目标 is the set control value of nitrate nitrogen concentration. This value should be lower than the corresponding effluent standard by 15 mg / L. To leave a redundancy, it is set to 12 mg / L;

[0054] n is the COD equivalent required to reduce 1 g of nitrate nitrogen. In theory, 2.86 g of COD is required to reduce 1 g of nitrate nitrogen for denitrification. However, in actual operation, COD cannot be completely used for the denitrification reaction. Generally, it is considered that COD / N between 4 and 6 can meet the carbon source required for the denitrification reaction. It is set to 5 g COD / gN;

[0055] y is the COD equivalent of the carbon source used, 300000 mg / L;

[0056] Set the PLC control terminal to receive the on-line nitrate nitrogen content data monitored by the on-line nitrate nitrogen detector 3 and adjust the carbon source dosage T of the carbon source dosing system 5 in real time, which can ensure the denitrification efficiency of the sewage. At the same time, it can avoid excessive carbon source. The remaining carbon source organic matter will cause an increase in the effluent COD, increase the treatment cost, and may also cause secondary pollution. It can not only ensure enough carbon source for denitrification, but also avoid excessive amount causing secondary pollution and cost waste.

[0057] The length of the corridor 1 is 114 m, and the water depth is about 6 m. Three submersible propellers 6 are set at equal distances of 29 m. The power of the submersible propeller 6 is 3 kw per unit. The following data are monitored before and after the optimization of the corridor 1 on a daily basis:

[0058]

[0059] Table 2 Comparison of energy consumption before and after the optimization of the present invention

[0060] After the transformation and optimization, the pollutant concentrations continuously monitored under the same working conditions are shown in Table 3 below. The data show that after the transformation, the denitrification effect has been improved by 27%. Due to the relatively high nitrate nitrogen concentration, an absolute anaerobic environment cannot be formed for the removal of orthophosphate, but the influence is small.

[0061] Inlet (mg / L) Outlet (mg / L) COD 13.89 12.68 Ammonia nitrogen 0.16 0.17 Nitrate nitrogen 10.45 7.63 Orthophosphate 0.87 0.84

[0062] Table 3 Key pollutant concentrations at the inlet and outlet of the end corridor of the aerobic tank after the transformation

[0063] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An in-situ optimization and energy-saving system for the end of an aerobic tank for sewage treatment, comprising a corridor (1), characterized in that: The gallery (1) is located at the end of the aerobic zone, and an ammonia nitrogen online monitor (2) for real-time monitoring of the ammonia nitrogen content of the influent is installed at the water inlet end of the gallery (1). A plurality of groups of surface aeration systems (4) arranged at equal distances are arranged in the gallery (1), and the ammonia nitrogen online monitor (2) and the surface aeration system (4) are both connected to a PLC control end; The water inlet end of the corridor (1) is equipped with an online nitrate nitrogen detector (3) for monitoring the nitrate nitrogen content of the inlet water, and the water inlet end of the corridor (1) is equipped with a carbon source dosing system (5) connected to the PLC control end; The carbon source dosing system (5) comprises a feed pipe (501), the feed end of the feed pipe (501) is connected to the discharge end of a metering pump (502), the feed end of the metering pump (502) is connected to an external carbon source storage device, and the metering pump (502) is connected to a PLC control end; The corridor (1), the ammonia nitrogen online monitor (2), the nitrate nitrogen online detector (3), the surface aeration system (4), the carbon source addition system (5) and the PLC control terminal constitute an adaptive dissolved oxygen control zone.

2. The in-situ optimization energy-saving system at the end of an aerobic tank for sewage treatment according to claim 1, characterized in that: The surface aeration system (4) comprises a rotating shaft (401), on which a plurality of rotating brushes (402) arranged in a circular array are mounted, and one end of the rotating shaft (401) is connected to a power output end of a motor (403).

3. The in-situ optimization energy-saving system at the end of an aerobic tank for sewage treatment according to claim 1, characterized in that: The feed pipe (501) is arranged in the middle of the corridor (1), and a plurality of groups of feed ports (503) arranged in equidistant arrays are installed on the feed pipe (501).

4. The in-situ optimization energy-saving system at the end of an aerobic tank for sewage treatment according to claim 3 is characterized by: A plurality of groups of submersible propellers (6) are installed in the corridor (1) at equal distances, the plurality of groups of submersible propellers (6) are installed in the middle of the corridor (1), and the plurality of groups of submersible propellers (6) are arranged in an alternating manner with the plurality of groups of surface aeration systems (4).

5. The in-situ optimization energy-saving system at the end of an aerobic tank for sewage treatment according to claim 4 is characterized by: The feed pipe (501) is arranged at the water inlet end of the gallery (1), and the first group of submersible thrusters (6) in the gallery (1) is arranged at the front end of the feed pipe (501).

6. The in-situ optimization energy-saving system at the end of an aerobic tank for sewage treatment according to claim 1, characterized in that: The PLC control end is responsible for controlling the amount of carbon source added to the corridor (1) by the metering pump (502). The PLC control end receives the online nitrate nitrogen content data monitored by the nitrate nitrogen online detector (3) to adjust the carbon source addition amount T of the carbon source addition system (5) in real time. The calculation formula of the carbon source addition amount T is: T=1000*Q(C 监测 -C 目标 )n / y Wherein, T is the amount of carbon source added, L / h; Q is the sewage flow, m 3 / h; C 监测 is the nitrate nitrogen concentration fed back by the online nitrate nitrogen monitor, mg / L; C 目标 The control value of nitric nitrogen concentration is set to 12 mg / L; n is the COD equivalent required to reduce 1g of nitrate nitrogen, set to 5gCOD / gN; y is the COD equivalent of the carbon source used, 300000 mg / L.

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