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Optimizing the hydraulic performance of a baffled horizontal subsurface flow constructed wetland through
Jiahao Wei1, Sarah Cotterill1, Jennifer Keenahan1
1UCD Dooge Centre for Water Resources Research, School of Civil Engineering, University College Dublin, Belfield, Newstead Building, Dublin 4, Ireland.
Journal of Environmental Management
|December 12, 2023
Summary
Baffled constructed wetlands (CWs) improve hydraulic efficiency. Increasing baffle numbers significantly enhances performance, while longer baffles offer diminishing returns, aiding wetland design optimization.
Area of Science:
- Environmental Engineering
- Fluid Dynamics
- Wastewater Treatment
Background:
- Traditional constructed wetlands (CWs) suffer from low hydraulic efficiency.
- A research gap exists concerning optimal baffle design (length and quantity) in CWs.
- Baffled CWs present a promising solution to enhance hydraulic performance.
Purpose of the Study:
- To comprehensively assess the combined influence of baffle length and quantity on CW hydraulic efficiency.
- To be the first study to use CFD for this specific investigation.
- To develop a predictive equation for hydraulic efficiency based on baffle configuration.
Main Methods:
- Utilized OpenFOAM for computational fluid dynamics (CFD) simulations at laboratory scale.
- Investigated baffle lengths from 0.4 to 0.58 m and baffle numbers from 0 to 11.
- Validated CFD simulations using experimental tracer tests (R² ranging from 0.84 to 0.93).
Main Results:
- Increasing baffle numbers significantly impacts Residence Time Distribution (RTD) curves.
- Baffle length has minimal effect on RTD when fewer than three baffles are used.
- Hydraulic efficiency increased by 58% with 5 baffles (0.58 m length); only 5.5% with increased length (0.4 to 0.5 m) at 11 baffles.
Conclusions:
- The number of baffles is a more critical factor than baffle length for improving hydraulic efficiency in CWs.
- A generalized predictive equation for hydraulic efficiency was successfully derived.
- Findings provide crucial insights for optimizing CW design and enhancing environmental engineering applications.
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