Deammonification of Cold Wastewater via Oxygen Control
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Solution Overview
Problem
Current biological purification methods for ammonium-containing wastewater, such as nitrification/denitrification, face high energy consumption and require large tank volumes due to slow growth rates of anaerobically ammonium-oxidizing bacteria, limiting their application to warm wastewaters with high nitrogen concentrations, and are not economically feasible for cold wastewaters with low nitrogen concentrations.
Innovation Solution
A method that utilizes a low oxygen concentration in the aeration tank to convert ammonium to elemental nitrogen using aerobically and anaerobically oxidizing bacteria, separates surplus sludge into heavy and light phases to enrich anaerobically ammonium-oxidizing bacteria, and feeds high-nitrogen sludge water to a deammonifying tank for further nitrogen conversion, allowing deammonification to occur even at low temperatures and low nitrogen concentrations without increasing tank volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If nitrification/denitrification is used for biological purification, then nitrogen is converted to elemental nitrogen, but energy consumption is high
Solution Approach 1:
The patent changes the oxygen concentration parameter in the aeration tank to a low oxygen level (0.5-2.0 mg/l), which fundamentally alters the biological process from conventional nitrification/denitrification to deammonification. This parameter change enables anaerobic ammonium-oxidizing bacteria to thrive and convert ammonium directly to nitrogen gas, significantly reducing energy consumption while maintaining nitrogen removal efficiency.
2Volume of stationary object
If conventional biological purification methods are used, then nitrogen removal is achieved, but large tank volumes are required due to slow growth rates of anaerobically ammonium-oxidizing bacteria
Solution Approach 1:
By adjusting the oxygen concentration to low levels and controlling the carbon-to-nitrogen ratio, the patent creates optimal conditions for anaerobic ammonium-oxidizing bacteria. This enables these slow-growing bacteria to accumulate effectively in the aeration tank, allowing for compact reactor design with reduced volume while maintaining high nitrogen conversion rates through enhanced bacterial activity.
3Loss of energy
If deammonification is applied to cold wastewaters with low nitrogen concentrations, then energy consumption is reduced, but process stability is compromised
Solution Approach 1:
The patent implements feedback control mechanisms to monitor and adjust operational parameters including oxygen concentration, carbon-to-nitrogen ratio, and hydraulic residence time. This feedback system ensures that conditions remain optimal for anaerobic ammonium-oxidizing bacteria, maintaining process stability even when treating cold wastewaters with low nitrogen concentrations, thereby achieving both energy reduction and reliable operation.
4Productivity
If organic carbon is consumed in denitrification, then nitrogen is removed, but this is disadvantageous for further purification process and sludge properties
Solution Approach 1:
The patent extracts and eliminates the need for organic carbon consumption in the nitrogen removal process. By using anaerobic ammonium-oxidizing bacteria that convert ammonium directly to nitrogen gas without requiring organic carbon, the process avoids carbon depletion while maintaining effective nitrogen removal. This extraction of the carbon requirement enables subsequent purification steps and sludge treatment to proceed without carbon limitation constraints.
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 enables efficient biological purification of cold wastewater with reduced energy consumption and stable process operation by enriching anaerobically ammonium-oxidizing bacteria, allowing deammonification in cold wastewaters without the need for large tank volumes, and promotes a shift towards deammonification over nitrification/denitrification, achieving effective nitrogen elimination with potential for smaller reaction volumes and reduced energy use.
Implementation Method 1
the aerobically ammonium-oxidizing bacteria (AOB) which convert ammonium to nitrite
Implementation Method 2
the anaerobically ammonium-oxidizing and elemental nitrogen-producing bacteria (ANAMMOX), in particular Planctomycetes, which carry out this step with the aid of the previously produced nitrite
Implementation Method 3
During the nitrification, ammonium is oxidized by oxygen via the intermediate nitrite to form nitrate
Implementation Method 4
In the subsequent denitrification, the nitrate is reduced in a first reduction step to nitrite, and in a second reduction step, to nitrogen
Implementation Method 5
During the sludge digestion, the organic constituents of the surplus sludge from the secondary clarifier and of the sludge withdrawn from the wastewater in the primary clarifier are converted into gas (methane)
Data Source
AI summary
A method for the biological purification of ammonium-containing wastewater. The wastewater is purified in an aeration tank in which a low oxygen concentration of less than 1.0 mg/l is set so as to first convert, using aerobically oxidizing bacteria, ammonium contained in the wastewater to nitrite and then to convert, using anaerobically oxidizing bacteria, ammonium and nitrite to elemental nitrogen. At least a part of surplus sludge formed in the aeration tank is separated into a heavy sludge phase and a light sludge phase. The light sludge phase is fed as surplus sludge to a sludge digestion. Sludge water that is separated off from the sludge in a sludge dewatering is fed to a deammonifying tank. Nitrogen compounds in the sludge water are converted, by deammonification in the deammonifying tank, to elemental nitrogen. Surplus sludge formed in the deammonifying tank is fed to the aeration tank.