Solid Digestate Methane Recovery in Unheated Sealed Tanks
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Solution Overview
Problem
Existing biogas production processes do not effectively recover residual biogas from solid digestate, leading to greenhouse gas emissions and suboptimal energy yield.
Innovation Solution
A process involving the separation of digestate into solid and liquid phases, followed by anaerobic digestion in sealed tanks without heating or mixing, using inert gases like CO2 or nitrogen, and recovering biogas from these tanks to enhance biogas yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the digestate is subjected to anaerobic digestion in conventional digesters with heating and mixing, then the biogas production rate is improved, but the energy consumption and operational complexity increase
Solution Approach 1:
The invention utilizes the self-heating effect of anaerobic digestion itself, where the microbial activity generates sufficient heat to maintain the digestion process without external heating. The system is designed to be thermally autonomous, converting the chemical energy of organic matter directly into thermal energy for process maintenance.
Solution Approach 2:
The invention extracts and removes the heating and mixing systems from the anaerobic digestion process, demonstrating that these conventional components are not essential for effective biogas production from solid digestate. The simplified system achieves comparable or superior productivity through natural convection and microbial action alone.
2Productivity
If the digestate is subjected to anaerobic digestion with heating and mixing, then the biogas production efficiency is improved, but the device complexity increases
Solution Approach 1:
The invention removes heating and mixing equipment from the anaerobic digestion system, proving that these complex mechanical and thermal control systems are unnecessary for effective biogas production. The simplified design reduces operational complexity while maintaining or improving productivity through natural process dynamics.
Solution Approach 2:
The system performs all necessary functions through self-regulating microbial processes, where the digestate itself provides the energy for heating and the natural convection currents provide mixing, eliminating the need for external control systems and reducing operational complexity.
3Object-generated harmful factors
If residual biogas from solid digestate is not recovered, then the process simplicity is maintained, but greenhouse gas emissions increase
Solution Approach 1:
The invention separates the digestate into solid and liquid fractions, directing only the solid portion to additional anaerobic digestion for residual biogas recovery. This segmentation allows targeted gas recovery without complicating the overall process, capturing emissions that would otherwise be released while maintaining operational simplicity.
Solution Approach 2:
The system creates an anaerobic (inert) environment in the second digestion stage to prevent aerobic decomposition and associated greenhouse gas emissions, capturing the biogas that would otherwise be released into the atmosphere while maintaining a simple closed-system approach.
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
Enhances biogas recovery from solid digestate, reducing greenhouse gas emissions and improving energy efficiency while maintaining the agronomic qualities of the digestate.
Implementation Method 1
a step of anaerobic digestion in the tank with neither heating nor mixing
Implementation Method 2
The degradation may be natural, like that observed in swamps or in household rubbish dumps; however, the production of biogas can also result from the methanization of waste in a dedicated reactor
Implementation Method 3
a step of recovering the digestate at the outlet of a digester, a post-digester or a storage tank; b) a step of separating the digestate into a solid digestate and a liquid digestate
Data Source
AI summary
Process for producing biogas from a digestate obtained from a digester, said process comprising a step of recovering the digestate at the outlet of a digester, a post-digester or a storage tank; a step of separating the digestate into a solid digestate and a liquid digestate; a step of introducing the solid digestate into at least one closed tank; a step of anaerobic digestion in the tank with neither heating nor mixing; and a step of recovering the biogas at the tank outlet.