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2003
Author(s): Davis, A.P. M. Shokouhian, H. Sharma, C. Minami, and D. Winogradoff.
Title: “Water Quality Improvement through Bioretention: Lead, Copper, and Zinc Removal”
Journal (Issue): Water Environment Research, 75(1): 73-82.
Study Type: Laboratory and Field
Description: Synthetic stormwater was applied to pilot-plant bioretention systems and 2 existing facilities. Removal rates based on concentration and load reductions were close to 100% for heavy metals (lead, copper, and zinc). For most samples, effluent copper and lead values were less than 5 ug/L, and zinc levels were less than 25 ug/L. Somewhat less removal was noted for shallower systems (less than 30 cm). The field investigations supported the laboratory experiments. Accumulation of metals could be a concern, but build-up problems wouldn’t be expected for at least 15 years because metal concentrations are low in runoff.
Author(s): Kim, H., E.A. Seagren, and A.P. Davis.
Title: “Engineered Bioretention for Removal of Nitrate from Stormwater Runoff”
Journal (Issue): Water Environment Research, 75(4): 355-367.
Study Type: Laboratory
Description: Studied the effects of including a continuously submerged anoxic zone in the bottom of a bioretention cell in order to improve nitrate reduction by creating anaerobic (denitrifying) conditions. Four phases were examined: (1) finding a potential electron donor (shredded newspaper worked best), (2) optimizing the nitrate loading and hydrologic loading rate, (3) performance was analyzed for various dormant periods (recovery of long dormant phases were effective for the 2 longest dormant periods – 30 and 84 days), and (4) running samples for a pilot-scale bioretention system. The results showed the effectiveness of a continually submerged anoxic zone with an overdrain to remove nitrate by denitrification in bioretention cells.
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