Volumetric Clarifying Filtration of Urban Source Area Rainfall Runoff

• Published in: Journal of environmental engineering (New York, N.Y.) Vol. 135; no. 8; pp. 609 - 620
• Main Authors: Sansalone, J. J, Liu, B, Kim, J.-Y
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01.08.2009
• Subjects: Applied sciences; Attenuation; Backwashing; Best Management Practice; Chemical engineering; Clarifiers; Coefficients; Computational fluid dynamics; Continental surface waters; Couples; Effluents; Environmental engineering; Exact sciences and technology; Filters (fluid); Filtration; Flow rate; Fluid flow; Frequency distribution; Head loss; Hydraulics; Hydrology; Influents; Mathematical models; Media; Natural water pollution; Pollution; Porosity; Rainfall; Rainwaters, run off water and others; Retention; Ripening; Runoff; Sediments; Separation; Stormwater management; TECHNICAL PAPERS; Unsteady; Urban areas; Water treatment and pollution; Watersheds; USA, Louisiana, Baton Rouge; Filter medium; Urban area; Retention; Modeling; Clarifying; Rain; Selfpurification; Loading; Watershed; Stormwater management; Filtration; Urban areas; Prediction; Hydrodynamics; Runoff water; Sedimentation; Best Management Practice; Head loss; Ripening; Hydrology; Suspended particle; Particle size distribution; Pressure drop; Runoff; Aerosols; Porosity; Storm water
• ISSN: 0733-9372; 1943-7870
• DOI: 10.1061/(ASCE)EE.1943-7870.0000044

Volumetric clarification is a common storm-water unit operation for hydrologic attenuation that couples particulate matter (PM) separation. Recent volumetric clarification can also include integrated filtration. This study examines the unsteady hydraulic and head loss response of a volumetric clarifying filter (VCF) system to urban source area hydrologic loadings in Baton Rouge, La for 19 fully captured events. The rainfall-runoff response of the 1,088  m2 paved watershed is examined as a direct VCF loading. Watershed responses yielded two classes of behavior; high volume events with an equilibrium volumetric runoff coefficient from 0.6–0.8 while low volume events were 0.4–0.6. Runoff PM as suspended sediment concentration (SSC) yielded coarse heterodisperse influent particle-size distributions (PSDs); transformed to finer and more monodisperse PSDs after treatment. While event-mean head loss is less than 25 mm, instantaneous values up to 200 mm were dependent on instantaneous flow to the filters. Without backwashing, filter ripening head loss is small due to the coarse uniform filter media and radial filter configuration, with a loss of 2% porosity across the series of 19 events. Despite filter ripening an Ergun model was capable of predicting head loss across the entire flow rate range. Head loss and flow frequency distributions were exponential. Results indicate that a volumetric clarifier, filter geometry, and engineered media combination are capable of reducing effluent SSC to <30 mg/L through serial mechanisms of sedimentation followed by filtration.