Microbial Electrolysis Carbon Capture for Low C/N Wastewater
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Solution Overview
Problem
Traditional biological nitrogen removal technologies face challenges with high ammonia nitrogen wastewater having a low carbon-to-nitrogen (C/N) ratio, as they require additional carbon sources, leading to increased treatment costs and inefficiencies, particularly in Anammox processes which struggle with carbonaceous pollutant removal and nitrate-nitrogen conversion.
Innovation Solution
A system integrating a carbon capture apparatus using microbial electrolytic cells, an integrated anaerobic ammonium oxidation reactor, autotrophic denitrification apparatus, and denitrification sedimentation tank, which captures carbon through microbial electrolysis and utilizes recovered hydrogen and sulfur as electron donors for denitrification, enhancing nitrogen and sulfur removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional biological nitrogen removal (nitrification and denitrification) is applied to wastewater with low C/N ratio, then nitrogen removal can be achieved, but additional carbon source must be added leading to increased treatment cost
Solution Approach 1:
The patent converts the harmful low C/N ratio condition into a benefit by using the limited carbon source in the wastewater efficiently through Anammox process, which requires minimal external carbon addition compared to traditional denitrification. The system transforms the constraint of low carbon availability into an advantage by employing bacteria that can remove nitrogen with very little carbon demand.
Solution Approach 2:
The patent changes the operational parameters by maintaining a specific dissolved oxygen concentration range (0.5-2.0 mg/L) in the reaction tank to create optimal conditions for Anammox bacteria. This parameter control allows the system to achieve high nitrogen removal efficiency while minimizing carbon source requirements, thereby reducing treatment costs.
2Quantity of substance
If Anammox process is used for high ammonia nitrogen wastewater removal, then nitrogen removal efficiency is improved, but nitrate-nitrogen remains after treatment failing to meet stringent environmental requirements
Solution Approach 1:
The patent segments the nitrogen removal process into two stages: first, Anammox process for high-efficiency ammonia nitrogen removal; second, a polishing stage using heterotrophic bacteria to convert remaining nitrate-nitrogen into nitrogen gas. This segmentation allows each stage to optimize for its specific function, ensuring both high ammonia removal and complete nitrogen elimination to meet environmental standards.
Solution Approach 2:
The patent maintains continuous operation of the Anammox process with steady aeration and substrate supply, ensuring consistent ammonia nitrogen removal. The continuous conversion of ammonia to nitrite and then to nitrogen gas, followed by continuous polishing of residual nitrate, ensures uninterrupted nitrogen removal activity that reliably meets emission requirements.
3Quantity of substance
If dedicated biochemical process is designed for removing COD from low carbon source wastewater, then carbonaceous pollutant removal can be achieved, but it becomes inefficient and costly
Solution Approach 1:
The patent makes the Anammox reaction tank serve multiple functions: it simultaneously removes ammonia nitrogen through Anammox process and removes carbonaceous pollutants (COD) using the limited carbon source present in the wastewater. This multi-functionality eliminates the need for a separate dedicated COD removal process, thereby maintaining high treatment efficiency while avoiding additional costs.
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 system achieves high-performance nitrogen removal and negative carbon discharge with a 90% COD removal rate, 80-93% carbon capture, and increased nitrate-nitrogen removal loading, while reducing construction and operation costs by leveraging energy production and efficient bacterial enrichment.
Implementation Method 1
a carbon capture apparatus (3), wherein the carbon capture apparatus (3) comprises an anode chamber (4) and a cathode chamber (5) which are arranged side by side and are separated by an ion exchange resin membrane (9); the anode chamber (4) is communicated with the water intake pump (1) via a water inlet pipe (2) and is provided with an anode plate (6); the cathode chamber (5) is provided with a cathode plate (7) electrically connected to a negative electrode of a power source (8)
Implementation Method 2
a bottom of the cathode chamber (5) is provided with aerators (10) connected to a first air compressor (11) by means of a first pipe
Implementation Method 3
the anode chamber (4) and the cathode chamber (5) are spaced apart by an ion exchange resin membrane (9)
Implementation Method 4
a carbon recovery sedimentation tank (13), an integrated anaerobic ammonium oxidation apparatus (16), an autotrophic denitrification apparatus (25) and a denitrification sedimentation tank (30) that are connected in sequence by means of pipes
Data Source
AI summary
A system for biological nitrogen removal and negative carbon discharge from wastewater with low carbon-to-nitrogen ratio may include a water intake pump, a carbon capture apparatus, a carbon recovery sedimentation tank, an integrated ammonium apparatus, an autotrophic denitrification apparatus and a denitrification sedimentation tank that are connected in sequence by pipes. The carbon capture apparatus may include an anode chamber communicated with the water intake pump via a water inlet pipe and a cathode chamber communicated with the carbon recovery sedimentation tank via a first water outlet pipe. The anode and cathode chambers may be spaced apart by an ion exchange resin membrane. The anode and cathode chambers may be provided with an anode plate and a cathode plate electrically connected to positive and negative electrodes of a power source, respectively. A bottom of the cathode chamber may be provided with aerators connected to a first air compressor by a pipe.