Wastewater Aeration Control via Nitrate Feedback
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Solution Overview
Problem
Conventional wastewater treatment systems face challenges in controlling aeration amounts based on fluctuating organic and ammonia loadings, leading to inefficiencies in denitrification and nitrification treatments, which affect nitrogen removal rates and water quality.
Innovation Solution
A wastewater treatment method that uses a control unit to adjust gas supply amounts in a reaction tank based on real-time measurements from nitrate and ammonia meters, optimizing oxygen supply and controlling denitrification and nitrification processes to improve nitrogen removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If influent proportional control is used to supply air in proportion to influent amount, then aeration coverage is improved, but nitrogen removal efficiency deteriorates due to excess or shortage of air when organic loading and ammonia loading fluctuate
Solution Approach 1:
The patent employs feedback control by measuring nitrate concentration at a specific position in the reaction tank and using this measurement to adjust the gas supply amount. The control unit continuously monitors nitrate levels and modifies aeration accordingly, creating a closed-loop system that adapts to fluctuating loading conditions while maintaining optimal nitrogen removal efficiency
Solution Approach 2:
The patent changes the control parameter from influent flow proportion to nitrate concentration-based control. By measuring nitrate concentration and adjusting gas supply based on this parameter, the system dynamically adapts to varying organic and ammonia loadings, ensuring both adequate aeration coverage and sustained nitrogen removal efficiency
2Measurement precision
If DO control or ammonia control is used to maintain predetermined concentrations, then aeration precision is improved, but denitrification treatment cannot be controlled in previous stages
Solution Approach 1:
The patent segments the reaction tank into different functional zones by positioning the nitrate concentration measurement point at a specific location (near the outflow portion). This spatial segmentation allows independent control of denitrification in upstream stages while maintaining nitrification control in downstream stages, enabling both precision and versatility simultaneously
Solution Approach 2:
The patent uses nitrate concentration measurement as an intermediary parameter to bridge denitrification and nitrification control. By measuring nitrate concentration at an intermediate position and using it to control gas supply, the system can indirectly control both denitrification processes in previous stages and nitrification processes, achieving comprehensive control capability
3Productivity
If ammonia control is used to supply appropriate air according to ammonia loading, then nitrification control is improved, but denitrification treatment in previous stages remains uncontrollable
Solution Approach 1:
The patent performs preliminary measurement of nitrate concentration at a strategically positioned point that reflects the cumulative effect of previous denitrification stages. This preliminary information is then used to adjust gas supply in advance, enabling control of both denitrification and nitrification processes before the water exits the reaction tank
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 method ensures appropriate oxygen supply and controlled denitrification and nitrification treatments, enhancing the quality of treated water by stabilizing nitrogen removal rates and optimizing gas usage.
Implementation Method 1
a nitrate concentration measuring unit that measures the nitrate concentration of the water to be treated at a desired position
Implementation Method 2
a gas supply-amount control unit that controls the amount of gas supplied from the air diffusing unit (6) based on the nitrate concentration
Implementation Method 3
an air diffusing unit (6) that diffuses air into the water to be treated (1)
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
When biological treatment is performed with respect to water to be treated flowing in a plurality of aerobic tanks 2a to 2d that constitute a reaction tank 2, the water to be treated is aerated by air diffuser units 6a to 6d. A nitrate meter 7 is provided on an inflow side of the aerobic tank 2c, which is a desired position along a flow of the water to be treated in the reaction tank 2 to measure a nitrate concentration, and an ammonia meter 11 is provided near an outflow side of the reaction tank 2 to measure an ammonia concentration. A control unit 9 supplies a control signal to gas supply-amount control units 10a to 10d so that both the nitrate concentration and the ammonia concentration fall within respective predetermined ranges based on the values of the nitrate concentration and the ammonia concentration, and controls a gas supply amount from the air diffuser units 6a to 6d to the water to be treated for each of the air diffuser units 6a to 6d or collectively in the air diffuser units 6a to 6d.