Bioretention

Capture and Fate of Suspended Solids in Bioretention

This project began in early 2003.  The purpose of this project is to determine suspended solids removal performance and the relative colloid movement in bioretention media.  Facility clogging and the long-term performance of bioretention as a storm water runoff management practice will depend greatly on the mechanisms of particle capture and their incorporation into the bioretention media matrix.  The governing equations for suspended solids movement and deposition include mass balance and kinetic equations.  Suspended solids removal and deposition profiles with depth will be studied.  Parameters to be evaluated include the suspended solids concentration, cumulative runoff volume, theoretical filter capacity, particle attachment coefficient, and hydraulic conductivity.

Column tests will be completed to examine various sizes of suspended solids in runoff water and capture by bioretention media of known particle size distribution.  Breakthrough curves will be employed for obtaining model parameters. Governing equations will be simulated via numerical methods for long-term prediction of suspended solids removal, solids profiles, and local hydraulic conductivity. 

Preliminary results suggest that TSS capture is described via deep bed filtration leading to cake filtration. Consequently, a deep soil media is not required. This conclusion has major implications to the design of bioretention cells for applicability and cost reduction.

This work is being completed by Doctoral student Houng Li.

Bioretention Installations