Anaerobic Wastewater Biomass Separation via Biogas Flotation
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Solution Overview
Problem
Existing anaerobic purification processes for wastewater often result in poor and inconsistent biomass separation, leading to unreliable processing outcomes.
Innovation Solution
A process involving the injection of biogas under pressure into the reactor contents, followed by a pressure reduction in a secondary tank, facilitates effective floatation separation of biomass from treated wastewater, forming a floating biomass layer that can be easily recycled back to the reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate degasification and solids settling steps are used, then gas and biomass can be removed from reacted liquid, but the process becomes complex and time-consuming
Solution Approach 1:
The patent combines degasification and solids settling into a single flotation tank where both functions occur simultaneously. Gas bubbles rise and carry biomass particles to the surface, achieving both gas removal and biomass separation in one unit operation rather than requiring separate sequential steps.
Solution Approach 2:
The flotation tank serves multiple functions: it acts as a degasifier to remove dissolved gas from the liquid, a settling tank to separate biomass from treated wastewater, and a flotation device to concentrate biomass at the surface. This multi-functional design simplifies the overall process while maintaining effective separation.
2Productivity
If gas is entrained in reacted liquid, then anaerobic fermentation can proceed, but biomass particles become difficult to settle
Solution Approach 1:
The patent uses pneumatic principles by introducing pressurized gas into the flotation tank to create bubbles. These bubbles rise through the liquid and attach to biomass particles, carrying them to the surface where they can be easily removed. This pneumatic flotation mechanism overcomes the settling problem caused by entrained gas.
Solution Approach 2:
The patent exploits the phase transition of gas from dissolved state to bubble formation. By reducing pressure or introducing nucleation sites in the flotation tank, dissolved gas comes out of solution as bubbles, which then attach to biomass particles and facilitate their separation from the liquid phase.
3Reliability
If floatation separation is used, then biomass can be separated from treated wastewater, but the process requires precise control of temperature and pressure
Solution Approach 1:
The flotation process is driven by the system's own biogas production. The gas generated during anaerobic fermentation is reused as the flotation medium, eliminating the need for external gas supplies or complex temperature-pressure control systems. The process self-regulates based on the fermentation activity.
Solution Approach 2:
The patent simplifies operation by allowing the system to automatically adjust to varying conditions. The flotation effectiveness is maintained through natural variations in gas production and dissolution that occur during normal fermentation operations, without requiring precise manual control of temperature and pressure parameters.
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 method enhances biomass separation efficiency, preventing biomass from sinking and achieving a cleaner treated wastewater with reduced suspended solids, improving the overall anaerobic purification process.
Implementation Method 1
the biogas is injected under pressure into the tank contents to provide a pressurized tank contents, wherein the gas is dissolved in the tank contents
Implementation Method 2
the pressure in the second tank is lower than in the first tank, to provide a floating biomass layer and a treated wastewater layer
Implementation Method 3
solution gas dissolved in said liquid is liberated therein forming bubbles which rise and cause said suspended bacterial cell mass particles to be floated to the surface of said liquid
Data Source
AI summary
The present invention relates to a process for the separation of biomass in the anaerobic purification of wastewater and to a system for the separation of biomass in the anaerobic purification of wastewater.