Ultralow DO Aeration Control via Oxygen Consumption Rate Calculation
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Solution Overview
Problem
Current methods for controlling aeration airflow in activated sludge treatment systems, particularly for low DO operation, face challenges in maintaining accurate oxygen balance and stability due to variations in wastewater composition and fluctuations, leading to difficulties in simultaneous BOD and denitrification treatment.
Innovation Solution
A method that involves acquiring an aeration airflow correlation using a measuring device to sample and aerate activated sludge, calculating oxygen consumption rates, and adjusting aeration airflow to maintain ultralow DO levels, thereby improving measurement accuracy and frequency, especially during large raw water load fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If DO is controlled to low levels (0.5 mg/l or less) to save aeration power and enable simultaneous BOD treatment and denitrification, then energy consumption is reduced and treatment efficiency is improved, but measurement accuracy and stable control become difficult to maintain
Solution Approach 1:
The system performs preliminary calibration by establishing the relationship between aeration airflow rate and DO value before actual control operation. This preliminary action creates a reference map that enables accurate control at low DO levels without requiring continuous complex measurements during operation.
Solution Approach 2:
The invention uses a measuring device that replicates the aeration tank environment on a smaller scale. By copying the essential characteristics of the full system in a controlled measurement setup, the system can accurately determine oxygen consumption rates and establish airflow-DO relationships without the measurement uncertainties present in the full-scale low DO environment.
2Use of energy by moving object
If aeration airflow is reduced for low DO operation, then energy consumption decreases, but the ability to maintain stable oxygen balance under fluctuating wastewater conditions deteriorates
Solution Approach 1:
The system continuously monitors DO levels and oxygen consumption rates, using this feedback to dynamically adjust aeration airflow. The control unit processes real-time data and modifies airflow commands to maintain the target low DO level even when wastewater characteristics fluctuate, ensuring stable operation.
Solution Approach 2:
The invention transitions from static aeration control to dynamic control that adapts to changing conditions. By continuously calculating oxygen consumption rates and adjusting airflow in real-time based on actual DO measurements and process conditions, the system maintains stability despite fluctuations in wastewater load and composition.
3Ease of operation
If DO meter is used for aeration control, then simple measurement is possible, but accurate tracking of oxygen supply balance under fluctuating conditions becomes difficult
Solution Approach 1:
The system introduces an intermediary measuring device that indirectly determines oxygen consumption rates through calibrated measurements of aeration airflow and DO relationships. This intermediary approach translates simple DO meter readings into accurate information about oxygen balance by using pre-established correlations between airflow rate and DO value.
Solution Approach 2:
The invention replaces direct mechanical/chemical DO measurement with a calculation-based approach. By substituting physical measurement with mathematical calculation of oxygen consumption rates based on airflow-DO relationships, the system achieves higher precision while maintaining operational simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the stability and accuracy of BOD/denitrification simultaneous treatment by reducing energy consumption and maintaining optimal aeration airflow, even with fluctuating raw water conditions, facilitating efficient ultralow DO control.
Implementation Method 1
aeration device that bubbles air into activated sludge
Implementation Method 2
dissolved oxygen concentration... oxygen supply capacity by aeration
Implementation Method 3
oxygen consumption rate... respiration of activated sludge microorganisms... BOD components in wastewater with microorganisms
Data Source
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AI summary
[Object] To provide a method for appropriately controlling an aeration volume for activated sludge on which aeration treatment is conducted while DO of an activated sludge mixed liquor in an aeration tank is being adjusted to substantially 0 mg/l (ultralow DO treatment). [Solution] (1-0) An aeration volume correlation (G = F(Gr)) between an aeration tank and a measuring device is acquired in advance. (1-1) A sample of activated sludge mixed liquor taken during ultralow DO treatment operation is temporarily intensely aerated in the measuring device and then aeration is stopped. (1-2) Based on temporal changes in the measuring device DO value, an oxygen consumption rate Rr and an equilibrium DO value C1 are calculated. (1-3) An appropriate aeration volume G2* of the testing device is acquired by using an Ea-G relationship formula and the like obtained in advance. (1-4) An appropriate aeration volume Gr2* of the aeration tank is obtained by using the relationship G = F(Gr) obtained in (1-0).