Development of a Small-Scale, High Efficiency Bioremediation System for Removing Nitrate from Nursery Runoff Water

Authors: WILSON, CHRIS - University Of Florida; MOZADEN, MIGUEL - University Of Florida; Albano, Joseph; ROLEN, CATHERINE - University Of Florida

Submitted to: Southern Nursery Association Research Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/6/2006
Publication Date: 9/1/2006
Citation: Wilson, C., Mozaden, M., Albano, J.P., Rolen, C. 2006. Development of a Small-Scale, High Efficiency Bioremediation System for Removing Nitrate from Nursery Runoff Water. Southern Nursery Association Research Conference. 51:552-554.

Interpretive Summary: Significant amounts of nitrate nitrogen may leave nursery production sites in runoff water generated during normal irrigation events. With increased pressures from state and federal regulatory agencies, nursery managers will need to reduce nutrient export from production areas to natural water bodies. Results from these studies indicate that a microbe-based bioremediation system may potentially be highly efficient at removing nitrate from drainage water within a short period of time. This type of system may be a viable option for space-limited nurseries faced with future regulation and associated financial obligations.

Technical Abstract: Nitrate concentrations in runoff water from the nursery ranged from 70 to 253 mg NO3-N/L. An estimated 62 to 67% of the nitrate applied during fertigation events left the production site in runoff water. Irrigation losses during these events accounted for 36 to 49% of the amount applied, with flow rates ranging from 9.3 to 19.1 L/minute. Native nitrate removal micro-flora were successfully captured from the UF/IFASIRREC surface water canal and the four different nurseries in South Florida. Under optimal conditions, nitrate removal rates of >90% removal within 8 hours were achieved after 3 to 5 days acclimation; and >90% removal within 4 hours was achieved after 7 to 14 days acclimation depending on the site. To achieve these rates, the micro-flora must be exposed to nitrate on a daily basis. When nitrate was pulsed at 3 or 5 day intervals, microflora never achieved 90% removal in less than 10 hours. Under the pulsed scenario, microflora was able to achieve 90% removal within 24 hours after 16 days. Once optimal nitrate removal rates were achieved, pulsing of carbon significantly reduced nitrate removal rates, making it impossible to estimate removal times since nitrate tended to accumulate over time with the daily additions. Results indicated that all of the alternate sources of carbon performed similarly.