Deammonification Sludge Separation for Low-Temperature Stability
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Solution Overview
Problem
Conventional sewage treatment methods for nitrogen elimination in ammonium-containing wastewater require large reaction volumes and are economically unfeasible at low temperatures due to the slow growth rate of anaerobic ammonium-oxidizing bacteria and the presence of nitrite-forming bacteria with shorter generation times, leading to oxygen-limited conditions and inefficient ammonium conversion.
Innovation Solution
The method involves separating excess sludge into a heavy phase containing anaerobic ammonium-oxidizing bacteria (AMOX) and a light phase, with the heavy phase being returned to the system and the light phase disposed of, allowing enrichment of AMOX bacteria, enabling operation at lower temperatures and increased oxygen concentrations, thus enhancing process stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional biological nitrification/denitrification is used for nitrogen elimination, then nitrogen can be converted to elementary nitrogen, but large reaction volumes are required due to slow bacterial growth rates
Solution Approach 1:
The patent changes the operational parameters by maintaining anaerobic conditions during the ammonium oxidation step and using a single-basin configuration. This allows AMOX bacteria to thrive and convert ammonium to nitrogen directly, eliminating the need for large volumes required in conventional two-stage systems. The key parameter change is the creation of anaerobic microenvironments within the aerated basin to support AMOX activity.
2Loss of energy
If the waste water temperature is kept low to reduce heating costs, then energy consumption decreases, but the growth of anaerobic ammonium-oxidizing bacteria is inhibited
Solution Approach 1:
The patent changes the chemical parameters by maintaining very low oxygen concentrations (0.2-2.0 mg O2/l) during the ammonium oxidation phase. This creates anaerobic conditions that allow AMOX bacteria to function at lower temperatures without requiring heating, thus reducing energy consumption while maintaining bacterial activity.
3Productivity
If nitrite-forming bacteria are present in the system, then they can convert ammonium to nitrite under aerobic conditions, but they outcompete anaerobic ammonium-oxidizing bacteria due to shorter generation times
Solution Approach 1:
The patent applies local quality by creating distinct microenvironments within the single basin: anaerobic zones where AMOX bacteria convert ammonium to nitrogen, and aerobic zones where AOB convert ammonium to nitrite. By controlling oxygen distribution locally, the system prevents nitrite-forming bacteria from dominating while maintaining both functional groups.
Solution Approach 2:
The patent uses dynamic control of oxygen supply, varying it throughout the day to match ammonium loading patterns. Oxygen is supplied at lower concentrations (0.2-2.0 mg O2/l) during ammonium oxidation to favor AMOX bacteria, then increased during denitrification phases. This dynamic adjustment prevents nitrite-forming bacteria from outcompeting AMOX bacteria.
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 increases the proportion of AMOX bacteria, reduces the required reaction volume, and maintains process stability and efficiency at lower temperatures, allowing for effective deammonification even at 15°C, while enabling higher oxygen concentrations for improved nitrite formation.
Implementation Method 1
The fact that the two groups of bacteria (aerobic/anaerobic) do not occur in the flock network as in other biological wastewater treatment systems and each have a different density means that the excess sludge can be separated into a heavy and a light phase
Implementation Method 2
aerobic ammonium oxidizing bacteria (AOB), which convert ammonium to nitrite
Implementation Method 3
anaerobic ammonium oxidizing and elementary nitrogen-producing bacteria (AMOX), in particular planctomycetes, which carry out this step complete with the help of the previously produced nitrite
Data Source
Figure 1
AI summary
The method for treating ammonium-containing wastewater (3) in a deammonified activated sludge system, comprises converting ammonium to nitrite using aerobic oxidizing bacteria, subsequently converting the ammonium and nitrite into elementary nitrogen using anaerobic oxidizing bacteria such as Planctomycetes, discharging surplus sludge, which is developed during the process, from the tank, and separating the discharged surplus sludge into a heavy phase that contains anaerobic ammonium oxidizing bacteria and into a lighter phase. The method for treating ammonium-containing wastewater (3) in a deammonified activated sludge system, comprises converting ammonium to nitrite using aerobic oxidizing bacteria, subsequently converting the ammonium and nitrite into elementary nitrogen using anaerobic oxidizing bacteria such as Planctomycetes, discharging surplus sludge, which is developed during the process, from the tank, and separating the discharged surplus sludge into a heavy phase that contains anaerobic ammonium oxidizing bacteria and into a lighter phase, where the heavy phase is led back and/or collected in the system. The separation of the surplus sludge is carried out in a hydrocyclone (8) and in a centrifuge, and by sedimentation.