External Selector Granular Sludge Phosphorus Removal
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Solution Overview
Problem
Current wastewater treatment methods for phosphorus removal rely on chemical precipitation or anaerobic selectors, which are costly, inefficient, and vulnerable to disruptions from nitrate and oxygen contamination, and require specific wastewater characteristics.
Innovation Solution
An apparatus and method utilizing an external gravimetric or size selector to create densified biomass aggregates that establish substrate and electron acceptor gradients, allowing for biological phosphorus removal without formal anaerobic selectors, using a hydrocyclone, centrifuge, or screen to separate and retain granular sludge, promoting anoxic environments for specific organism growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical precipitation is used for phosphorus removal, then phosphorus removal efficiency is improved, but operational complexity and chemical costs increase
Solution Approach 1:
The patent replaces chemical precipitation (chemical system) with biological phosphorus removal through granular sludge processes (biological system). The granular sludge creates internal gradients that enable phosphorus removal through biological mechanisms rather than chemical addition, eliminating the need for chemical dosing systems and reducing operational complexity.
Solution Approach 2:
The granular sludge structure enables self-organizing of functional zones within the granule itself. The dense core creates anaerobic conditions automatically, and the gradient structure enables phosphorus accumulation without external chemical inputs or complex control systems, allowing the system to serve itself.
2Reliability
If anaerobic selectors are used for biological phosphorus removal, then phosphorus removal is achieved, but vulnerability to nitrate and oxygen contamination increases
Solution Approach 1:
The patent creates local anaerobic conditions within the dense core of granular sludge granules rather than requiring a separate anaerobic selector zone. This localized approach allows phosphorus removal to occur in protected micro-environments within the granule, making the process less vulnerable to bulk liquid contamination with nitrate or oxygen.
Solution Approach 2:
The patent nests functional zones within the granular sludge structure itself - the dense core contains anaerobic conditions for phosphorus removal, while the outer layers handle other treatment functions. This nested structure protects the phosphorus removal function from external contamination while maintaining process efficiency.
3Reliability
If formal anaerobic selectors are used, then phosphorus removal is achieved, but process complexity and space requirements increase
Solution Approach 1:
The patent merges the phosphorus removal function with the main aerobic treatment process by using granular sludge that can perform both functions simultaneously. The granular structure enables anaerobic phosphorus removal and aerobic treatment to coexist in the same reactor, eliminating the need for separate anaerobic selector tanks and reducing process complexity.
Solution Approach 2:
The granular sludge system performs multiple functions within a single process - phosphorus removal, nitrogen removal, and organic matter degradation - all within the same reactor configuration. This multi-functional approach eliminates the need for dedicated anaerobic zones and simplifies the overall process design.
4Speed
If granular sludge is used, then settling velocity is improved, but diffusion resistance inside granules increases
Solution Approach 1:
The patent accepts and utilizes the diffusion resistance created by the dense granular structure as a beneficial feature. The gradient that forms due to diffusion limitations creates the anaerobic core conditions necessary for phosphorus removal. Rather than trying to eliminate diffusion resistance, the system exploits it to create the necessary environmental gradients.
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 enhances phosphorus removal efficiency and reliability, reduces chemical usage, and minimizes disruptions from nitrate and oxygen, achieving stable and efficient biological phosphorus removal without the need for chemical precipitation or dedicated anaerobic zones.
Implementation Method 1
an external gravimetric selector operating on the biomass waste stream for collecting and retaining densified biomass aggregates including dense granule selection
Implementation Method 2
using a hydrocyclone, centrifuge, or screen to separate and retain granular sludge
Implementation Method 3
an external gravity settling device for separating dense sludge aggregates
Data Source
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AI summary
A method and an apparatus for biological wastewater treatment that includes a biological selector and a physical selector. The apparatus comprises an internal biological reactor where wastewater and recycled biomass are combined to provide a high substrate and high electron acceptor gradient for generating morphological biomass features that favor granule formation over floc and filament formation, and an external gravimetric or external screen selector operating on the biomass waste stream for collecting and retaining densified biomass aggregates including dense granule selection and for wasting lighter filaments and flocs. In the method and apparatus, particles may be added to provide cores to promote the formation of aggregates encapsulating the seeded particles. The particles may be added as various materials, for example, in the bioreactor, to initiate or seed the formation of a granule, that could then be separated by or integrated with either the external gravimetric or external screen selector. Further, organisms may be selected for biological phosphorus removal, denitrifying methane oxidizers, biological sulfur or sulfide oxidation, methanogenesis.