External Biomass Separator for Granular Sludge Recirculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional anaerobic sludge bed reactors face challenges in efficiently separating biomass, water, and biogas due to issues such as sludge settling at the bottom, blocking extraction ports, and inefficient recirculation, particularly during low biogas production or start-up, with existing systems prone to blockage and maintenance difficulties.
Innovation Solution
An external separation chamber is used outside the bioreactor, combined with a gas lift effect or venturi-effect to separate and recycle biomass without mechanical pumps, enhancing separation efficiency and reducing maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an internal three-phase separator device is used inside the reactor, then separation of gas, liquid, and solid phases is achieved, but sludge settles at the bottom blocking extraction ports and causes maintenance difficulties
Solution Approach 1:
The separator is extracted from the interior of the reactor and placed in the exterior recirculation line. This allows the separation function to be maintained while the separator becomes externally accessible for maintenance, eliminating the blockage problem inside the reactor and enabling easy removal and cleaning of the separator without shutting down the entire reactor system.
Solution Approach 2:
The system is segmented into separate functional zones: the reactor for biological treatment and the external separator for phase separation. This spatial segmentation allows independent maintenance of each component, with the separator being accessible outside the reactor while the reactor continues to operate.
2Productivity
If mechanical pumps are used for biomass recirculation, then recirculation is achieved, but system complexity and maintenance needs increase
Solution Approach 1:
The mechanical pump system is replaced with a gas lift system that uses biogas bubbles to provide buoyancy force for lifting the sludge-water mixture. This substitution eliminates mechanical moving parts, reducing system complexity and maintenance requirements while maintaining effective biomass recirculation.
Solution Approach 2:
The system uses pneumatic principles by introducing biogas into the recirculation line to create a gas-lift effect. The gas bubbles rise through the sludge-water mixture, providing the necessary hydraulic lift to return biomass to the reactor without mechanical pumping.
3Productivity
If mechanical pumps are used for biomass recirculation, then recirculation is achieved, but energy consumption increases
Solution Approach 1:
The mechanical pump is replaced by utilizing the potential energy stored in biogas. The gas expansion and buoyancy forces naturally lift the sludge mixture, converting chemical energy from biogas production directly into mechanical lift energy, thereby eliminating the need for external electrical energy input for recirculation.
Solution Approach 2:
The system uses its own produced biogas to drive the recirculation process. The biogas generated during anaerobic digestion serves dual purposes: as a product and as the driving force for biomass recirculation, making the system self-sufficient and energy-positive.
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 efficient separation of gas, liquid, and solid phases with reduced risk of malfunction, improved biomass structure, and energy savings, while simplifying maintenance and operation.
Implementation Method 1
at least in part by making use of a gas lift effect
Implementation Method 2
at least in part by making use of a venturi-effect
Implementation Method 3
an external separator (2) comprising a separation chamber provided with tilted internals, wherein the fluid comprising the biomass withdrawn from the upper part of the bioreactor is separated into a liquid phase
Data Source
AI summary
A method for treating an aqueous fluid comprising a biodegradable organic substance in an installation comprising an upflow bioreactor containing a sludge bed, said sludge bed comprising biomass, an external separator, and a conditioning tank, the method comprising: treating the fluid in the conditioning tank; feeding the treated fluid into a lower part of the bioreactor and forming biogas; withdrawing the fluid from an upper part of the bioreactor, which withdrawn fluid comprises biomass; feeding the aqueous fluid withdrawn from the upper part of the bioreactor into the external separator wherein the aqueous fluid comprising the biomass is separated into a liquid phase, and a fluid phase enriched in biomass; returning said fluid phase enriched in biomass from the external separator to the bioreactor; and returning a part of said liquid phase to the conditioning tank.