Wastewater Oxygen Control via Nitrogen Rate Monitoring
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Solution Overview
Problem
Existing methods for regulating oxygen supply in wastewater treatment processes based on oxidation-reduction potential and dissolved oxygen measurements are prone to deviations due to sensor sensitivity issues and inaccurate representation of nitrification and denitrification reactions, leading to inefficient energy consumption and potential treatment failures.
Innovation Solution
A method that uses continuous measurement of ammoniacal nitrogen (NH4) and nitrate (NO3) levels to control oxygen supply, stopping oxygen introduction when the rate of nitrate reduction becomes less than a low threshold and the sum of NH4 and NO3 measurements exceeds a high threshold, optimizing energy use and improving treatment efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen supply is regulated based on oxidation-reduction potential and dissolved oxygen measurements, then the aeration process can be controlled, but measurement deviations occur due to sensor sensitivity issues and inaccurate representation of nitrification and denitrification reactions
Solution Approach 1:
The patent changes the measurement parameters from oxidation-reduction potential and dissolved oxygen to direct measurements of ammoniacal nitrogen and nitrate concentrations. This parameter change enables more accurate and reliable control of the aeration process by measuring the actual nitrogen compounds involved in nitrification and denitrification reactions, eliminating sensor sensitivity issues associated with the previous parameters.
2Productivity
If oxygen supply is continuously regulated to optimize treatment, then energy consumption increases, but treatment efficiency improves
Solution Approach 1:
The patent implements a feedback control system that continuously monitors ammoniacal nitrogen and nitrate concentrations and adjusts oxygen supply accordingly. The control algorithm increases aeration when ammoniacal nitrogen levels are high (nitrification phase) and reduces or stops aeration when nitrate levels are high (denitrification phase), optimizing energy consumption while maintaining treatment efficiency.
Solution Approach 2:
The patent dynamically adjusts the oxygen supply rate based on real-time measurements of nitrogen compound concentrations and the current phase of the biological treatment process. The system transitions between nitrification and denitrification phases, optimizing aeration at each stage rather than maintaining constant aeration, thereby reducing overall energy consumption while maintaining high treatment efficiency.
3Ease of operation
If fixed aeration time limits are used to control the process, then operation is simplified, but energy optimization is poor due to safe parameter settings
Solution Approach 1:
The patent replaces fixed time-based control with feedback-based control using continuous measurements of ammoniacal nitrogen and nitrate concentrations. The system automatically determines when to switch between nitrification and denitrification phases based on measured concentrations, eliminating the need for conservative safe parameter settings and optimizing energy consumption without complicating operation.
4Productivity
If ammoniacal nitrogen and nitrate measurements are used to control oxygen supply, then treatment efficiency improves, but sensor drift errors affect low concentration measurements
Solution Approach 1:
The patent implements prior cushioning by setting minimum and maximum time delays for aeration and anoxia phases, as well as safeguard conditions that prevent premature switching between phases. These protective measures ensure proper functioning of biological reactions even when sensor drift occurs at low concentrations, maintaining treatment efficiency while compensating for measurement uncertainties.
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 reduces energy consumption by ensuring oxygen is supplied only when necessary, enhancing the efficiency of nitrification and denitrification processes while minimizing errors associated with sensor drifts, particularly at low concentrations.
Implementation Method 1
a first aeration phase in order to oxidize in particular the compounds carbonated and nitrogenous using aerobic bacteria
Implementation Method 2
a second anoxic phase for the reduction of nitrites and nitrates formed during the previous aeration phase
Data Source
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AI summary
The invention relates to a method for controlling oxygen supply in a tank (2) for biologically treating wastewater by alternating aeration including consecutive cycles, wherein each cycle comprises a first aeration phase and a second anoxic phase for reducing nitrites and nitrates formed during the preceding aeration phase, the tank is provided with sensors for measuring ammonia nitrogen (4b) and for measuring nitrate (4c) and optionally for measuring oxygen (4a) that is dissolved in the tank liquor or in the liquor thereof exiting the tank, a method according to which the oxygen supply is controlled in the aeration phase when the reduction speed of the nitrate measurement is less than a bottom threshold and the cutoff of the oxygen supply is also controlled in the aeration phase when at least one of the following triggering events occurs: the reduction speed in the measurement of ammonia nitrogen becomes lower than a bottom threshold; the total sum of ammonia nitrogen and nitrate measurements becomes higher than a top threshold, said thresholds may be dependent on time delays and on a top threshold for the dissolved oxygen measurement.