Anoxic Biofilter for H2S Removal Without Nitrogen Dilution
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Solution Overview
Problem
Current methods for removing hydrogen sulfide (H2S) from energy production gas streams, such as biogas, natural gas, and shale gas, are costly and inefficient, particularly when using biofilter systems that require additional oxygen as an electron acceptor, leading to nitrogen dilution and quality issues in the treated gas.
Innovation Solution
An aqueous biofilter system using a biofilter bed with microorganisms capable of anoxic H2S oxidation, where an aqueous nitrate solution is added to the gas stream before contact, allowing H2S oxidation under anoxic conditions, reducing nitrogen influx and maintaining gas quality, with a chelating agent like EDTA to prevent clogging, and a controller for adjusting nutrient dosages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional biofilter systems use aerobic microorganisms to remove H2S, then H2S removal is achieved, but nitrogen dilution occurs and gas quality deteriorates
Solution Approach 1:
The patent changes the oxygenation state parameter from aerobic to anoxic conditions, enabling H2S oxidation without introducing nitrogen. This fundamental parameter change resolves the contradiction by maintaining H2S removal efficiency while eliminating nitrogen dilution that degrades gas quality.
Solution Approach 2:
The patent introduces nitrate as an intermediary electron acceptor instead of direct oxygen use. Nitrate serves as a mediator that enables H2S oxidation through alternative biochemical pathways, achieving the same H2S removal function without the harmful nitrogen dilution effect associated with aerobic processes.
2Reliability
If aqueous solutions are added to the gas stream for H2S removal, then H2S oxidation is enhanced, but clogging issues arise in the biofilter
Solution Approach 1:
The patent introduces a chelating agent as an intermediary substance that mediates between the aqueous nitrate solution and the biofilter media. The chelating agent prevents direct interaction that causes clogging while maintaining the beneficial H2S oxidation function of the nitrate solution.
Solution Approach 2:
The patent extracts or removes the clogging-causing components from the aqueous solution through the use of chelating agents, separating the harmful effect (clogging) from the useful effect (H2S oxidation). This allows the beneficial function to continue without the harmful side effect.
3Reliability
If conventional H2S removal methods are used, then H2S is removed from the gas stream, but the process becomes costly and complex
Solution Approach 1:
The patent merges multiple functions into a single biofilter system: H2S oxidation, nitrate delivery, and clogging prevention all occur within the same reactor without requiring separate treatment stages. This integration simplifies the overall process and reduces complexity compared to conventional multi-step methods.
Solution Approach 2:
The patent enables the biofilter system to be self-sufficient by using recirculated treated gas as the carrier for nitrate delivery, eliminating the need for external oxygen supply systems or complex control mechanisms. The system serves itself by utilizing its own output for its input requirements.
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 provides a simple, cost-effective method for achieving a 99.5% H2S removal efficiency while maintaining the quality of the energy production gas stream, reducing nitrogen dilution, and preventing clogging issues within the biofilter.
Implementation Method 1
oxidation of at least part of the H2S in the H2S contaminated energy production gas stream by the microorganisms under anoxic conditions
Implementation Method 2
microorganisms that are capable of oxidizing H2S... oxidation of at least part of the H2S... by the microorganisms
Implementation Method 3
wherein the process further comprises the steps of adding an aqueous nitrate solution to the H2S contaminated energy production gas stream prior to being contacted with the microorganisms
Data Source
Figure 1
AI summary
The invention relates to a process and a biofilter system (10) for removing H2S from a H2S contaminated energy production gas stream containing methane. The aqueous biofilter system comprises a biofilter (6) having biofilter support material constituting a biofilter bed supporting a humidified biofilm having microorganisms that are capable of oxidizing H2S. The process comprises the steps of contacting the H2S contaminated energy production gas stream with the microorganisms of the humidified biofilm, and oxidation of at least part of the H2S in the H2S contaminated energy production gas stream by the microorganisms, resulting in a H2S depleted energy production gas stream, wherein the process further comprises the step of adding an aqueous nitrate solution to the H2S contaminated energy production gas stream prior to being contacted with the microorganisms, enabling the microorganisms to oxidize the H2S under anoxic conditions. The invention furthermore relates to the use of such a biofilter system (10) in the removal of H2S from a H2S contaminated energy production gas stream containing methane.