Two-Layered Microbial Film for Anaerobic Ammonia Oxidation
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Solution Overview
Problem
Conventional biological nitrogen removal methods using anaerobic ammonia oxidation reactions face limitations in ammonia nitrogen concentration, water temperature, and pH value, making it difficult to achieve denitrification at a practical level across various wastewater conditions, particularly in municipal and domestic wastewater with lower temperatures and nitrogen concentrations.
Innovation Solution
The method involves adjusting the flow rate of water over a support with a two-layered microbial film, controlling the feed rate of the support, and optimizing operational conditions such as DO value and ORP to enhance nitrite type nitrification, thereby inhibiting nitrate type nitrification and securing necessary nitrous acid for anaerobic ammonia oxidation, allowing denitrification to occur under a wider range of conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional biological nitrogen removal methods are used, then ammonia nitrogen can be converted to nitrogen gas through nitrification and denitrification, but the process requires large amounts of oxygen and organic matter addition, increasing running costs
Solution Approach 1:
The invention changes the fundamental reaction parameters by using anaerobic ammonia oxidation instead of aerobic nitrification followed by denitrification. This parameter change eliminates the need for large amounts of oxygen and organic matter, directly reducing running costs while maintaining nitrogen removal efficiency
Solution Approach 2:
The invention extracts and removes the need for organic matter addition and large oxygen supply from the nitrogen removal process. By using anaerobic ammonia oxidizing bacteria, the system eliminates these costly requirements while achieving the same nitrogen conversion function
2Loss of energy
If anaerobic ammonia oxidation reaction is used, then organic matter addition is omitted and sludge production is reduced, but limitations on ammonia nitrogen concentration, water temperature, and pH value remain
Solution Approach 1:
The invention creates different local environments within the reaction system by using a two-layered microbial film structure. The outer layer provides aerobic conditions for nitrite production while the inner layer provides anaerobic conditions for ammonia oxidation, allowing the system to overcome environmental limitations and expand its applicability
Solution Approach 2:
The invention uses a composite microbial film structure combining two types of bacteria in specific spatial arrangement. This composite structure enables the system to function under broader environmental conditions by integrating the functions of both aerobic and anaerobic processes within a single reactor
3Reliability
If separate tanks are provided for partial nitritation and denitrification with pH adjustment, then nitrogen removal can be achieved, but equipment cost increases and process complexity increases
Solution Approach 1:
The invention merges the partial nitritation and denitrification processes into a single reaction tank with a two-layered microbial film. This consolidation eliminates the need for separate tanks and pH adjustment systems, reducing equipment cost and operational complexity while maintaining nitrogen removal efficiency
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 practical-level denitrification efficiency in wastewater with relaxed limitations on ammonia nitrogen concentration, water temperature, and pH value, making it applicable to a broader range of wastewater types, including municipal and domestic wastewater.
Implementation Method 1
ammonia nitrogen is oxidized into nitrite nitrogen by making use of oxygen attributable to ammonia oxidizing bacteria under aerobic conditions
Implementation Method 2
The anaerobic ammonia oxidizing bacteria belong to a denitrification microorganism group capable of reacting ammonia nitrogen as an electron donor with nitrite nitrogen as an electron acceptor under anaerobic conditions to produce a nitrogen gas
Implementation Method 3
The moving speed, per unit surface area of the film, of ammonium ions to the microbial film is adjusted by increasing the flow rate of water to be treated at the surface portion of the support
Data Source
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AI summary
Provided is a biological nitrogen removal method making use of an anaerobic ammonia oxidation reaction, which includes, causing to flow a support, under aerobic conditions, in water to be treated containing a soluble nitrogen which has been poured in a reaction tank, the support having, on the surface portion thereof, a two-layered microbial film which holes, in the outer layer, nitrite type nitrifying bacteria contributing to a nitrite type nitrification reaction or aerobic bacteria decomposing the soluble nitrogen other than ammonia into ammonia and nitrite type nitrifying bacteria contributing to a nitrite type nitrification reaction as a dominant species and, in the inner layer, anaerobic ammonia oxidizing bacteria contributing to an anaerobic ammonia oxidation reaction as a dominant species while being surrounded with the nitrite type nitrifying bacteria; and thereby carrying out denitrification of the water to be treated by making use of the anaerobic ammonia oxidation reaction. In the biological nitrogen removal method, a feed rate of the support (total surface area of the support per unit capacity of the reaction tank) is adjusted so that an amount of nitrous acid produced by the nitrite type nitrification reaction through the action of the nitrite type nitrifying bacteria reaches a level to inhibit a nitrate type nitrification reaction.