Hollow Fiber Diffuser Oxygen Control for Nitrite Oxidation Inhibition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current membrane aerated biofilm reactors (MABRs) face challenges in efficiently inhibiting nitrite-oxidizing bacteria (NOB) while maintaining the activity of ammonia-oxidizing bacteria (AOB), leading to suboptimal oxygen transfer efficiency and increased energy consumption in nitrogen removal processes.
Innovation Solution
A hollow fiber diffuser module is used, where the gas mixture includes oxygen and carbon dioxide to adjust oxygen concentration, allowing for 100% utilization of supplied oxygen and maintaining anaerobic conditions, thereby suppressing NOB activity while promoting AOB dominance, and a separate tank with a nitrite oxidation suppressant is employed to inhibit NOB selectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional diffusers are used for oxygen supply in MABR, then oxygen transfer efficiency ranges from 10% to 40%, but 60% to 90% of fed oxygen is exhausted to air without being used, leading to high energy consumption
Solution Approach 1:
The patent employs a porous membrane diffuser that allows selective gas transfer. The membrane structure enables oxygen to diffuse into the liquid phase while preventing air from escaping back into the gas phase, achieving near 100% oxygen transfer efficiency and eliminating the 60-90% oxygen loss encountered with conventional diffusers.
Solution Approach 2:
The diffuser utilizes composite membrane materials that combine hydrophobic properties (to prevent liquid penetration) with controlled porosity (to allow gas diffusion). This composite structure enables selective oxygen transfer while maintaining structural integrity and preventing air back-diffusion, resolving the energy efficiency problem.
2Productivity
If oxygen supply is increased to maintain AOB activity, then nitrogen oxidation by AOB is promoted, but NOB activity increases concurrently, oxidizing nitrite to nitrate and reducing process efficiency
Solution Approach 1:
The porous membrane diffuser creates localized oxygen enrichment zones immediately at the membrane surface where AOB are positioned. This local quality approach ensures high oxygen concentration is available where AOB need it, while the hydrophobic membrane prevents oxygen from diffusing into bulk liquid where NOB would oxidize nitrite, thus promoting nitrogen removal while suppressing harmful nitrite oxidation.
Solution Approach 2:
The system segments the oxygen supply function into two distinct zones: (1) at the membrane surface where oxygen diffuses to support AOB activity for nitrogen oxidation, and (2) bulk liquid phase where oxygen is excluded to prevent NOB activity. This spatial segmentation resolves the contradiction between maintaining AOB productivity and preventing NOB harmful effects.
3Measurement precision
If membrane diffuser is used to achieve high oxygen transfer efficiency, then oxygen supply precision is improved, but device complexity increases due to membrane maintenance requirements
Solution Approach 1:
The hydrophobic porous membrane structure provides self-cleaning functionality through air flow that prevents liquid accumulation and biofouling. The membrane's inherent properties enable it to resist contamination without requiring complex external cleaning systems, maintaining oxygen supply precision while minimizing device complexity and maintenance burden.
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 significantly reduces the energy required for oxygen supply, achieving high oxygen transfer efficiency and stable nitrogen removal with reduced operational costs and minimal toxic suppressant discharge.
Implementation Method 1
A hollow fiber diffuser module is used, where the gas mixture includes oxygen and carbon dioxide to adjust oxygen concentration, allowing for 100% utilization of supplied oxygen
Implementation Method 2
the gas mixture includes oxygen and carbon dioxide to adjust oxygen concentration
Implementation Method 3
a separate tank with a nitrite oxidation suppressant is employed to inhibit NOB selectively
Data Source
AI summary
A device and method for shortcut nitrogen removal and nitrite-oxidizing bacteria activity inhibition are disclosed herein. An embodiment of the present invention provides a hollow fiber diffuser comprising: a plurality of hollow fibers on which bacteria can be attached and grow; and an inlet capable of supplying gas to one sides of the plurality of hollow fibers, wherein the gas includes oxygen and carbon dioxide, nitrite can be produced by the oxygen, and the concentration of oxygen in the gas is adjusted by the oxygen and the carbon dioxide.