Plug-Flow Reactor for Enhanced Phosphorus Release
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Solution Overview
Problem
Conventional enhanced biological phosphorus removal (EBPR) systems face challenges with long hydraulic retention times, high maintenance costs, and inefficient phosphorus and magnesium release due to struvite formation, leading to decreased anaerobic digester performance and increased operational expenses.
Innovation Solution
A plug-flow reactor system with multiple zones, including zones for concurrent thickening, denitrification, volatile fatty acid production, and solids separation, utilizing baffles for optimal phosphorus and magnesium release without the need for supplemental chemicals, and featuring a solids recycle system to decouple hydraulic and solids retention times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional complete or well-mixed anaerobic reactors are used with long hydraulic retention times (18-36+ hours), then sufficient phosphorus release is achieved, but the reactor volume, cost, and footprint requirements increase significantly
Solution Approach 1:
The reactor is divided into multiple zones with baffles to create plug-flow conditions, allowing different regions to perform different functions (phosphorus release, settling, thickening) simultaneously. This segmentation enables the system to achieve the same phosphorus release in a much smaller volume by eliminating the need for long retention times in a single large mixed reactor.
Solution Approach 2:
The system uses intermittent mixing rather than continuous mixing, and employs a decoupled hydraulic-solids retention time system where solids can be retained longer than the hydraulic retention time. This dynamic approach allows phosphorus release to occur efficiently in a shorter time frame while maintaining high solids concentrations for enhanced phosphorus kinetics.
2Quantity of substance
If continuous mixing is used in conventional reactors, then phosphorus release occurs, but dissolved oxygen concentrations and oxidation reduction potential increase due to air entrainment, reducing operational efficiency
Solution Approach 1:
The system uses intermittent mixing cycles rather than continuous mixing, allowing phosphorus release to occur during mixing phases while minimizing air entrainment and oxygen dissolution. This periodic action maintains anaerobic conditions more effectively while still achieving the necessary phosphorus release kinetics.
3Volume of stationary object
If hydraulic retention time is reduced in conventional reactors, then reactor volume and cost decrease, but additional equipment, processes, and chemicals are required at additional expense
Solution Approach 1:
The plug-flow reactor design combines multiple functions within a single reactor vessel: phosphorus release, solids settling, solids thickening, and hydraulic flow control. This multi-functionality eliminates the need for separate pre-thickening equipment, chemical addition systems, and post-reactor dilution/thickening facilities that would be required with conventional reduced-HRT systems.
4Quantity of substance
If conventional well-mixed reactors with long HRT are used, then phosphorus release is sufficient, but solids concentrations in reactor effluent are lower, reducing post-reactor solids separator efficiency and increasing chemical demand
Solution Approach 1:
The reactor includes a dedicated settling zone that separates solids from the phosphorus-rich effluent. This segmentation ensures that high solids concentrations are maintained in the reactor while the effluent has optimized solids content for downstream separation processes, eliminating the trade-off between phosphorus release and solids separation efficiency.
Data Source
AI summary
The invention relates to treatment of microorganisms from an activated sludge process operating with enhanced biological phosphorus removal in a reactor with baffles or other devices to induce similar plug-flow effort, designed to optimally release phosphorus and/or magnesium from the microorganisms with or without chemical addition. Further, the disclosure relates to a process designed to produce both a lower solids, phosphorus and magnesium enriched liquid stream and a higher solids, phosphorus and magnesium enriched stream. The reactor operates to give optimal performance by operating in a plug-flow mode.