Aeration control method for sewage treatment plant

Abstract

The invention relates to an aeration control method for a sewage treatment plant, which comprises the following steps of: setting an expected value of dissolved oxygen in a control system, and setting performance parameters of an air blower in the control system; the sludge oxygen consumption rate and the dissolved oxygen concentration in the sewage treatment tank are detected, the control system calculates the oxygen supply amount according to the detected sludge oxygen consumption rate and the detected dissolved oxygen concentration, and the control system calculates the aeration amount required by a dissolved oxygen set value according to the actual aeration parameters and the oxygen transfer rate; the control system automatically adjusts an air blower according to the aeration rate Q and the adjusting period T, and the aeration rate in the aeration tank is controlled. According to the method, the aeration control logic is optimized, the adjusting measures in the adjusting period are rapidly determined by utilizing the actual dissolved oxygen concentration value detected on line, the influence of the sewage temperature on oxygen dissolution is fully considered, and the control accuracy and efficiency of aeration adjustment in the aeration tank of the sewage plant are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to an aeration control method for a sewage treatment plant. Background Art

[0002] In the biological treatment of sewage, aeration is the link with the highest energy consumption, usually accounting for about 50% to 70% of the total power consumption of sewage treatment plants. Therefore, reducing the energy consumption in the aeration stage is the top priority for energy conservation and consumption reduction in sewage treatment plants. The aeration control strategy is to automatically and accurately control the aeration volume of the sewage treatment process by using automated control instruments and equipment to achieve stable effluent quality, energy conservation and consumption reduction, and reduce personnel intervention.

[0003] The most common aeration control method in China is still the relatively extensive manual debugging method, which usually determines the aeration volume based on the operator's experience. If there is no long-term and obvious fluctuation in the effluent water quality, the aeration volume will not be adjusted in real time. Once the operating conditions change, the aeration volume is still adjusted up or down based on experience, resulting in problems such as insufficient aeration or excessive aeration. The aeration system of some treatment plants even operates at a load exceeding the normal load for a long time, which not only fails to guarantee the effluent water quality, but also causes a lot of energy waste.

[0004] The DO (dissolved oxygen) control method is to adjust the air volume to a preset value through the DO concentration value monitored by PID feedback when the external conditions change regularly. However, there is a large lag problem in the changes in air volume, water quality and quantity of the incoming water, and the changes reflected in the dissolved oxygen, which makes this control method always "half a beat slower" and often misjudgments in adjustments, thus greatly reducing its practicality. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides an aeration control method for a sewage treatment plant to solve the technical problems existing in the prior art.

[0006] The technical objectives of the present invention are achieved through the following technical solutions: A method for controlling aeration in a sewage treatment plant comprises the following steps: Setting the expected value of dissolved oxygen in the control system and setting the performance parameters of the blower in the control system; Detect the oxygen consumption rate and dissolved oxygen concentration of sludge in the sewage treatment pool. The control system calculates the oxygen supply based on the detected sludge oxygen consumption rate and dissolved oxygen concentration. The control system calculates the aeration volume required for the dissolved oxygen set value based on the actual aeration parameters and oxygen transfer rate. The calculation formula for the aeration volume required to increase the actual dissolved oxygen concentration to the set value is: ; In the formula, Q is the aeration rate, OUR is the activated sludge oxygen consumption rate, is the volume of sludge in aeration, SOTE is the oxygen utilization rate of the aerator under standard conditions, V 曝气池 is the volume of the aeration tank, t℃ is the water temperature in the aeration tank; P 预期值 is the expected dissolved oxygen concentration, P 实际值 is the actual dissolved oxygen concentration; The control system automatically adjusts the blower according to the aeration volume Q and the adjustment period T to control the aeration rate in the aeration tank.

[0007] Preferably, the activated sludge oxygen consumption rate OUR is measured online by an oxygen consumption rate meter, and the time interval of the online measurement is 10 minutes.

[0008] Preferably, the actual dissolved oxygen concentration is obtained by real-time monitoring by a dissolved oxygen monitor.

[0009] Preferably, when the actual dissolved oxygen concentration value is less than the expected dissolved oxygen concentration value, the adjustment period T is set to 20 minutes under the condition that the sludge oxygen consumption rate remains unchanged, and the aeration rate within the adjustment period T is calculated by the calculated aeration volume Q, thereby increasing the blowing rate of the blower; When the actual dissolved oxygen concentration value is greater than the expected dissolved oxygen concentration value, the adjustment period T is set to 10 minutes under the condition that the sludge oxygen consumption rate remains unchanged, and the aeration rate within the adjustment period T is calculated by the calculated aeration volume Q, thereby reducing the blowing rate of the blower; The actual dissolved oxygen concentration value is detected every 10 minutes. When the actual dissolved oxygen concentration value is equal to the expected dissolved oxygen concentration value, the expected regulation target is achieved.

[0010] Compared with the existing method, the present invention has the following beneficial effects: The present invention optimizes aeration control logic, utilizes the actual dissolved oxygen concentration value detected online to quickly determine the adjustment measures within the adjustment period, and fully considers the influence of sewage temperature on oxygen dissolution, thereby improving the control accuracy and efficiency of aeration adjustment in the aeration tank of a sewage treatment plant.

[0011] The present invention can significantly reduce the energy consumption of an aeration system in a sewage treatment plant by optimizing the aeration control logic. DETAILED DESCRIPTION

[0012] The present invention is described in detail below in conjunction with specific implementation modes.

[0013] This embodiment provides an aeration control method for a sewage treatment plant, comprising the following steps: Setting the expected value of dissolved oxygen in the control system and setting the performance parameters of the blower in the control system; Detect the oxygen consumption rate and dissolved oxygen concentration of sludge in the sewage treatment pool. The control system calculates the oxygen supply based on the detected sludge oxygen consumption rate and dissolved oxygen concentration. The control system calculates the aeration volume required for the dissolved oxygen set value based on the actual aeration parameters and oxygen transfer rate. The calculation formula for the aeration volume required to increase the actual dissolved oxygen concentration to the set value is: ; In the formula, Q is the aeration rate, OUR is the activated sludge oxygen consumption rate, is the volume of sludge in aeration, SOTE is the oxygen utilization rate of the aerator under standard conditions, V 曝气池 is the volume of the aeration tank, t℃ is the water temperature in the aeration tank; P 预期值 is the expected dissolved oxygen concentration, P 实际值 is the actual dissolved oxygen concentration; The control system automatically adjusts the blower according to the aeration volume Q and the adjustment period T to control the aeration rate in the aeration tank.

[0014] In the above embodiment, the activated sludge oxygen consumption rate OUR is measured online by an oxygen consumption rate measuring instrument, and the time interval of the online measurement is 10 minutes.

[0015] It should be noted that the actual dissolved oxygen concentration is obtained by real-time monitoring by a dissolved oxygen monitor. Existing sewage treatment plants are equipped with oxygen consumption rate meters and dissolved oxygen monitors in aeration tanks. When implementing the present invention, the oxygen consumption rate meter and dissolved oxygen monitor are connected to the control system, and the blower is connected to the control system. The technical barriers to system transformation are relatively small, and the transformation cost is relatively low.

[0016] In some preferred embodiments, when the actual dissolved oxygen concentration value is less than the expected dissolved oxygen concentration value, the adjustment period T is set to 20 minutes under the condition that the sludge oxygen consumption rate remains unchanged, and the aeration rate within the adjustment period T is calculated by the calculated aeration volume Q, thereby increasing the blowing rate of the blower; When the actual dissolved oxygen concentration value is greater than the expected dissolved oxygen concentration value, the adjustment period T is set to 10 minutes under the condition that the sludge oxygen consumption rate remains unchanged, and the aeration rate within the adjustment period T is calculated by the calculated aeration volume Q, thereby reducing the blowing rate of the blower; The actual dissolved oxygen concentration value is detected every 10 minutes. When the actual dissolved oxygen concentration value is equal to the expected dissolved oxygen concentration value, the expected regulation target is achieved.

[0017] It should be noted that in order to improve the regulation efficiency of the aeration system, the detection cycle can be changed according to the water quality of the sewage treatment plant. When the water quality of the sewage treatment plant is relatively stable, the detection of the actual dissolved oxygen concentration value can be appropriately extended, for example, it can be extended to 20 minutes or 30 minutes. When the water quality of the sewage treatment plant is unstable, the detection cycle can be appropriately shortened, for example, it can be shortened to 8 minutes or 5 minutes, so as to further improve the aeration control efficiency and achieve the purpose of precise technology and energy saving.

[0018] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for controlling aeration in a sewage treatment plant, characterized in that: The following steps are involved: Setting the expected value of dissolved oxygen in the control system and setting the performance parameters of the blower in the control system; Detect the oxygen consumption rate and dissolved oxygen concentration of sludge in the sewage treatment pool. The control system calculates the oxygen supply based on the detected sludge oxygen consumption rate and dissolved oxygen concentration. The control system calculates the aeration volume required for the dissolved oxygen set value based on the actual aeration parameters and oxygen transfer rate. The calculation formula for the aeration volume required to increase the actual dissolved oxygen concentration to the set value is: ； In the formula, Q is the aeration rate, OUR is the activated sludge oxygen consumption rate, is the volume of sludge in aeration, SOTE is the oxygen utilization rate of the aerator under standard conditions, V 曝气池 is the volume of the aeration tank, t℃ is the water temperature in the aeration tank; P 预期值 is the expected dissolved oxygen concentration, P 实际值 is the actual dissolved oxygen concentration; The control system automatically adjusts the blower according to the aeration volume Q and the adjustment period T to control the aeration rate in the aeration tank.

2. A method for controlling aeration in a sewage treatment plant according to claim 1, characterized in that: The activated sludge oxygen consumption rate OUR is measured online by an oxygen consumption rate meter, and the time interval of the online measurement is 10 minutes.

3. A sewage treatment plant aeration control method according to claim 1, characterized in that: The actual dissolved oxygen concentration is obtained by real-time monitoring by a dissolved oxygen monitor.

4. A sewage treatment plant aeration control method according to claim 1, characterized in that: When the actual dissolved oxygen concentration value is less than the expected dissolved oxygen concentration value, the adjustment period T is set to 20 minutes under the condition that the sludge oxygen consumption rate remains unchanged, and the aeration rate within the adjustment period T is calculated by the calculated aeration volume Q, thereby increasing the blowing rate of the blower; When the actual dissolved oxygen concentration value is greater than the expected dissolved oxygen concentration value, the adjustment period T is set to 10 minutes under the condition that the sludge oxygen consumption rate remains unchanged, and the aeration rate within the adjustment period T is calculated by the calculated aeration volume Q, thereby reducing the blowing rate of the blower; The actual dissolved oxygen concentration value is detected every 10 minutes. When the actual dissolved oxygen concentration value is equal to the expected dissolved oxygen concentration value, the expected regulation target is achieved.

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