The WDOxy Fuzzy Model is a real-time calculation procedure for Variable Set-Point control of DO (dissolved oxygen). It determines the optimal oxygen concentration needed for the specific requirements of bacterial metabolism in carbon and nitrogen removal.
The procedure uses bio-process algorithms in Fuzzy Logic and online measurements of NH₄ (or alternatively ORP) together with DO, returning the optimal set-point value in real time. It is applicable to both continuous and intermittent aeration biological plants.
Importance of Dissolved Oxygen Control
Air supply is crucial for three main reasons:
- Oxygen supply represents one of the main operational cost items (10-30%)
- It is critical for the reliability of treated effluent quality
- It affects sludge and biomass settling efficiency
Dissolved Oxygen and Filamentous Bulking
DO concentration in the reactor significantly influences filamentous bulking and sludge settleability. The relationship between DO and SVI is directly influenced by organic loading (F/M): higher organic loads require higher dissolved oxygen concentrations to prevent filamentous bulking.
Limitations of Traditional Control
Traditional control with Fixed Set-Point has three main issues:
- Does not consider the actual treatment process performance
- Does not account for influent load variability
- Shows poor control stability with oversimplified methods
WDOxy-Fuzzy System Advantages
The Dynamic DO Set-Point system offers significant advantages:
- Immediate response: continuous set-point adaptation to manage peaks and load variability
- Process stability: remarkable stability compared to the traditional system, even facing significant variations
- Greater efficiency: particular reference to the nitrification process
- Energy savings: 15-20% consumption reduction, elimination of excess nitrification, improved oxygen transfer efficiency
- Guaranteed efficiency: ensures the required removal performance