Wastewater Reactor Clarifying Section for Struvite Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wastewater treatment systems face challenges in achieving efficient precipitation of solutes and preventing the entrainment of precipitate particles, particularly in fluidized bed reactors used for phosphorus removal and recovery, such as struvite precipitation, which can lead to inefficiencies and increased costs.
Innovation Solution
The implementation of a fluidized bed reactor design with a clarifying section that reduces fluid velocity and includes a recycling path to reintroduce wastewater, along with a flow distributor to uniformly collect and redistribute wastewater, helps in maintaining low fluid velocities and promoting the growth of larger struvite pellets while minimizing particle loss and construction costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluid velocity is increased to enhance mixing and precipitation reaction rate, then productivity is improved, but precipitate particles are entrained and lost in the effluent
Solution Approach 1:
The reactor is divided into distinct functional zones: a lower high-velocity reaction zone that promotes precipitation, and an upper low-velocity clarifying zone that allows particle settling. This segmentation enables different flow velocities in different regions, simultaneously achieving high reaction rates and effective particle retention.
Solution Approach 2:
The patent introduces a vertical dimension to flow velocity control, with velocity decreasing from bottom to top. This dimensional gradient allows the system to maintain high productivity in the reaction zone while achieving particle retention in the clarifying zone, resolving the contradiction between reaction rate and particle loss.
2Loss of substance
If a large clarifying section is added to reduce fluid velocity and prevent particle entrainment, then particle loss is reduced, but device complexity and construction costs increase
Solution Approach 1:
The clarifying section is integrated into the existing reactor structure as an upper extension rather than a separate external component. This merging approach allows the clarifying function to be achieved within the reactor footprint, reducing overall system complexity and construction costs while effectively preventing particle entrainment.
Solution Approach 2:
The reactor utilizes dynamic flow velocity variation with height, where velocity naturally decreases as fluid rises through the clarifying section. This dynamic velocity profile is achieved through the reactor's geometric design rather than additional mechanical components, simplifying the overall system while maintaining effective particle retention.
3Productivity
If recycle flow rate is increased to improve precipitation efficiency, then productivity is enhanced, but fluid velocity increases and causes particle entrainment
Solution Approach 1:
The reactor applies different flow conditions to different regions: high velocity in the lower reaction zone to enhance precipitation efficiency, and low velocity in the upper clarifying zone to prevent particle entrainment. This local differentiation of flow quality allows high recycle rates without particle loss.
Solution Approach 2:
The patent converts the potentially harmful effect of high velocity (particle entrainment) into a beneficial gradient by designing velocity to decrease vertically. The high velocity generated by increased recycle flow is confined to the reaction zone where it is beneficial, while the upper zone maintains low velocity for particle retention, effectively using the high velocity as a 'blessing' for precipitation while avoiding its 'curse' of entrainment.
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 the precipitation efficiency of struvite and other phosphorus-containing compounds, reduces particle entrainment, and lowers construction and operational costs by optimizing reactor design and flow management, achieving high recovery rates of phosphorus from wastewater.
Implementation Method 1
fluidized bed reactors
Implementation Method 2
clarifying section configured to provide a low fluid velocity. The clarifying section thereby helps to keep small particles of struvite or the like from exiting the reactor
Implementation Method 3
Struvite can be formed by the reaction: Mg2+ + NH4+ + P043- +6H20 ↔ MgNH4P04·6H2O
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Apparatus and methods for removing solutes from wastewater are disclosed. An embodiment provides a reactor tank having a manifold located at or near an interface between a lower (upstream) section having a first cross-section and a higher (downstream) section having a second cross-section smaller than the first cross section. An inlet for wastewater to enter the reactor tank is located in or below the first cross-section. A recycling path is provided for removing wastewater from the manifold and recycling at least part of the removed wastewater into the reactor tank. An outlet for water to exit the reactor tank is located downstream from the manifold.