Ammonia Oxidation Reactor with pH and DO Control for Wastewater
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Solution Overview
Problem
Conventional wastewater treatment processes require high aeration volumes and energy consumption to convert ammonium to nitrate, with nitrite being a transitional material in short supply, limiting the efficiency of ammonia removal.
Innovation Solution
A system comprising an ammonia oxidation reactor with controlled pH levels above 7.5 and dissolved oxygen levels below 1.0 mg/L, combined with a membrane reactor for separating solids and liquids, which favors the growth of ammonium oxidation bacteria and suppresses nitrite oxidation bacteria, enhancing the conversion of ammonium to nitrite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional biological nitrification process is used to convert ammonium to nitrate, then complete nitrogen removal is achieved, but excessive energy is consumed and large aeration footprint is required
Solution Approach 1:
The patent extracts and eliminates the nitrite oxidation step from the conventional nitrification process. By using free nitrous acid (FNA) dosing, the system selectively inhibits nitrite oxidation bacteria, allowing ammonium to be converted to nitrite without further oxidation to nitrate. This extraction of the unnecessary nitrate production step reduces aeration requirements and energy consumption while maintaining effective nitrogen removal through subsequent denitrification.
Solution Approach 2:
The patent applies parameter changes by controlling pH levels and FNA dosing to selectively inhibit nitrite oxidation bacteria while maintaining ammonium oxidation. By adjusting these chemical parameters, the system creates conditions favorable for partial nitrification (ammonium to nitrite) while suppressing complete nitrification (nitrite to nitrate), thereby reducing aeration energy requirements.
2Reliability
If high aeration volume is provided to ensure complete nitrification, then nitrate is produced, but the footprint of aeration unit becomes large
Solution Approach 1:
The patent removes the requirement for large aeration volumes by extracting the nitrite oxidation step. Through FNA dosing and pH control, the system achieves reliable partial nitrification (ammonium to nitrite) with significantly reduced aeration, eliminating the need for large aeration unit footprints while maintaining process reliability for nitrogen removal.
Solution Approach 2:
The patent applies partial action by intentionally stopping the nitrification process at the nitrite stage rather than allowing complete oxidation to nitrate. This partial nitrification approach, controlled through FNA dosing and pH management, provides sufficient nitrite for denitrification while requiring much smaller aeration volumes and footprint.
3Quantity of substance
If nitrite concentration is increased to improve ammonium oxidation in anammox process, then more electron acceptors are available, but nitrite is typically low as a transitional material
Solution Approach 1:
The patent applies preliminary action by proactively dosing FNA to control nitrite oxidation before it can occur naturally. This preemptive chemical dosing prevents the loss of nitrite to nitrate conversion, ensuring that nitrite accumulates at sufficient concentrations to support effective anammox reactions and maintain high ammonium oxidation rates.
Solution Approach 2:
The patent uses FNA as an intermediary substance to mediate between ammonium oxidation and nitrite oxidation processes. FNA acts as a selective inhibitor that allows the first step (ammonium to nitrite) to proceed while blocking the second step (nitrite to nitrate), thereby maintaining high nitrite concentrations for anammox without requiring increased aeration or changing fundamental bacterial kinetics.
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 achieves an ammonium conversion rate of over 80% to nitrite, reducing energy demand by more than 50% compared to conventional methods and minimizing the need for aeration and nitrate conversion.
Implementation Method 1
a membrane reactor disposed on the back of the ammonia oxidation reactor, wherein the membrane reactor comprises a membrane and an air aerator for separating the solids and liquids of the effluent of the ammonia oxidation reactor
Implementation Method 2
a membrane reactor disposed on the back of the ammonia oxidation reactor, wherein the membrane reactor comprises a membrane and an air aerator for separating the solids and liquids of the effluent of the ammonia oxidation reactor
Data Source
AI summary
Treatment system for wastewater containing ammonium is provided. The treatment system of the present invention includes an ammonia oxidation reactor and a membrane reactor disposed on the back of the ammonia oxidation reactor. The ammonia oxidation reactor includes biological carriers for carrying the ammonium oxidation bacteria and nitrite oxidation bacteria, a pH level controller for increasing the pH level to above 7.5, and a DO (dissolved oxygen) controller for reducing the DO content to less than 1.0 mg/L. The membrane reactor composed of a membrane and an aerator is used to separate the solids and liquids of the effluent of the ammonia oxidation reactor. In addition, a method for treating wastewater containing ammonium is also provided.