Tag Archives: Oxygen saturation

[EN] WDOxy/Fuzzy-control for improved Nitrogen Removal and Energy Saving in WWTP with predenitrification


Application of fuzzy-logic to improve the control of the activated sludge process. WDOxy-Controller is a dynamic (non-deterministic/fuzzy) approach model to “Dissolved Oxygen Control Strategy” in wastewater nutrient removing, basically based on using of Ione Selective (NH4+, NO3-) on-line analyzers, but in option it is possible to use on-line ORP/pH (Redox potential) low-cost sensors too. Fuzzy-logic based control strategies for wastewater treatment plants with pre-denitrification should lead to better effluent quality and, in parallel, to a reduction of energy consumption. The WDOxy goal is to develop a “dynamic DO set-up on need” calculation able to provide a continuous nutrient removal process control, under legal outlet limits and within a sustainable energy saving control. Compared to the operation with fixed nitrification/denitrification zones and constant DO concentrations, the required air-flow could be reduced up to 24% by using fuzzy-logic based control strategies. In fact, Traditional “DO Closed Loop Control” (aeration control) is a well-known automation procedure that does not allows to timely face the real need of oxidation that biological process dynamically requires from time to time. On the contrary, WDOxy control is able to face DO requirement, in all nutrient removal biological processes (N and P), in a cost efficient way, that means, by dosing energy on the base of a real-time evaluation of biomass metabolism.


The WDOxy fuzzy-controller procedure can be easily implemented in modern control and supervision systems and  the control characteristics can be followed and modified during operation.


For more info:


[EN] WWTP/check: Checking Procedure for Biological Nutrient Removal Processes with evaluation of possible Energy/Cost Saving in pre-Denitrification/Nitrification scheme

WWTPWWTPcheck – Math Model 

Nitrogen Removal and Control Strategy in Continuous-Flow-Aeration 

WWTPcheck Model is based on typical Mathematical Models referring in the field (ASM 1/2/3, WPRC), but it supplemented with Performance Indicators (KPIs), which also provide information on the Residual Depurative Capacity. The predenitrification process was first developed and proposed by Ludzack and Ettinger (1962) and later modified by Barnard (1973), who completely separated the anoxic and aerobic reactors, recycling the settler underflow to the anoxic reactor, and providing an additional recycle from the aerobic to the anoxic reactor, see Figure below:


WWTPcheck Flow scheme:  Modified Ludzack-Ettinger process (Denitro/Nitro)

Main Functionalities of Evaluation of WWTPcheck  procedure:

  • Percentage of Performance of Biological Nutrient Removal Process.
  • Min/Max values of Dissolved Oxygen required to avoid process problems (bulking, etc.).
  • Characterization of Functional Parameters of the Aeration System.
  • Percentage of possible Energy Saving in the Aeration System (variable DO setpoint calculation on the base of min/max biological need…).
  • Energy required for Aeration System.
  • Percentage of Electrical Energy Cost Saving.
  • Percentage of Sludge/Waste produced and their Cost.
  • Customized Input/Output Reporting.

The WWTP/check procedure is  available in MS-Excel file (.xls or .xlsx – MS Office-Excel 2007 or compatibles) to be better used as a checking tool and test.


For info or for a quote: