Radioactive Nitrate Waste Treatment via Denitrification and Reaeration
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Solution Overview
Problem
Conventional methods for treating radioactive nitrate waste liquids face challenges such as denitrifying bacteria perishing due to high nitrate concentrations, osmotic pressure issues leading to sludge flocculation, increased redundant sludge generation, and the need for compact, stable treatment facilities within controlled radiation areas.
Innovation Solution
The apparatus includes a denitrification tank with pH and carbon dioxide gas circulation, pH and carbon source adjustment systems, and solid-liquid separating units to maintain optimal conditions for denitrifying bacteria, preventing sludge flow and reducing redundant sludge generation, while using acetic acid as a carbon source and air supply to enhance treatment efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional biological reduction method is used with single carbon source, then nitrate can be reduced at ordinary temperature and pressure without ammonia generation, but the amount of redundant sludge generated increases and secondary waste disposal expense increases
Solution Approach 1:
The patent combines multiple carbon sources (methanol and acetate) into a single treatment system, allowing the denitrifying bacteria to utilize both carbon sources simultaneously. This merging of carbon sources maintains the benefits of biological reduction (no ammonia generation) while optimizing bacterial activity to reduce sludge production through more efficient nitrate reduction pathways.
Solution Approach 2:
The invention uses a composite carbon source system comprising both methanol and acetate, creating a synergistic effect where the combination of different carbon sources provides better nutritional balance for denitrifying bacteria, enhancing their reduction capability while minimizing excess sludge generation compared to using a single carbon source.
2Productivity
If high concentration nitrate waste liquid is treated, then treatment efficiency increases, but denitrifying bacteria may perish due to osmotic pressure and pH changes
Solution Approach 1:
The patent employs pH adjustment as a critical parameter change to maintain optimal conditions for denitrifying bacteria during high-concentration nitrate treatment. By controlling pH within the range of 6.5-8.5, the system prevents bacterial perishment while maintaining high treatment efficiency, addressing the contradiction between productivity and reliability.
Solution Approach 2:
The dual carbon source system acts as an intermediary that protects denitrifying bacteria from the harsh effects of high nitrate concentration. The combination of methanol and acetate provides a more balanced nutritional environment, reducing osmotic stress and supporting bacterial viability while enabling efficient nitrate reduction.
3Device complexity
If pH is not adjusted during denitrification, then process simplicity is maintained, but denitrifying bacteria perish due to pH rise
Solution Approach 1:
The patent implements automatic pH adjustment using pH-sensitive probes and automated dosing systems that monitor and adjust pH in real-time without requiring manual intervention. This self-service approach maintains bacterial viability through continuous pH control while minimizing the operational complexity burden on the operator.
Solution Approach 2:
The system incorporates pH monitoring with feedback control mechanisms that automatically adjust the carbon source dosing rate based on measured pH values. This feedback loop ensures pH remains within the optimal range for bacterial survival, resolving the contradiction between process simplicity and bacterial viability through automated control.
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
The solution effectively treats high-nitrate waste liquids by maintaining bacterial viability, reducing sludge flow, and minimizing redundant sludge, thereby enhancing denitrification performance and compactness of treatment facilities, while stabilizing reactions and reducing disposal costs.
Implementation Method 1
nitrate ions in a nitrate waste liquid are reduced to nitrogen gas (N2) according to a reaction based on the following formula (1) by an action of an anaerobic microorganism (denitrifying bacteria)
Implementation Method 2
aerobic microorganism that oxidizes and decomposes organic substances
Implementation Method 3
a carbon dioxide gas circulation system that circulates carbon dioxide gas into the denitrification tank
Data Source
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AI summary
To provide an apparatus for treating a radioactive nitrate waste liquid that includes a denitrification tank (12A) which accommodates active sludge that adsorbs or takes in the radioactive substance in a nitrate waste liquid (11) and in which an anaerobic microorganism that reduces the nitrate to nitrogen gas grows, and a reaeration tank (14) in which a denitrification-treated liquid (24) treated in the denitrification tank (12A) is aerated and mixed with active sludge. A pH adjuster (21), a carbon source (22), and nitrogen gas are supplied to the denitrification tank (12A) so as to separate a denitrified liquid into a solid content and the denitrification-treated liquid (24) by using a first solid-liquid separating film (25), and the denitrification-treated liquid (24) treated with the active sludge in the reaeration tank (14) is reaerated and separated into a solid content and a reaeration-treated liquid (27) by using a second solid-liquid separating film (28).