Use of Algae Reactors to Remediate Eutrophication in the Mississippi River Delta

1. Use of Algae Reactors to Remediate Eutrophication in the Mississippi River Delta Brendan Scott Joseph Vassios BZ 572 November 9, 2010

2. Mississippi River Basin 1.5 Million Square Miles

3. Ecology of Hypoxia

4. Introduction – Mississippi River • Increased fertilization and leaching of top soil has increased nitrogen concentrations in the Mississippi River and consequently the Gulf of Mexico • Increased concentrations of nitrogen has led to seasonal eutrophication of the Gulf of Mexico

5. Nitrogen • Nitrogen is used by plants for: • Nucleic acid (DNA & RNA) • Amino acids • Pigments • Eutrophication as a result of increased nitrogen can lead to: • Detrimental algae blooms • Reduced dissolved oxygen (hypoxia) • Fish kills

6. http://toxipedia.org/display/toxipedia/Algal+Bloom

7. Nitrogen’s Role in Eutrophication http://www.physicalgeography.net/fundamentals/9s.html

8. Current Regulation of Nitrogen • EPA limits for nitrogen in drinking water: • Nitrate – 10 ppm • Nitrite – 1 ppm • Ammonia – Varies • Total N – 11 ppm • Leaching from agricultural soils is currently unregulated

9. USGS, 2010

10. Nitrogen Levels Directly Proportional to Amount of Tile Farming USGS, 2010

11. Current Remediation Strategies • Current strategies incorporate mitigation by altering farming processes • Reduce nitrogen inputs • Crop rotation • Modified cultural practices • Previous research using algae for wastewater remediation (phytoaccumulation): • Algae turf scrubber • Algae biofilm

12. Algae Turf Scrubber

13. Algae Biofilm Qun et al., 2008

14. Algae Biofilm ~80% Reduction in Total N Qun et al., 2008

15. Potential Algae Species Anabaena cylindrica Spirogyra sp. http://plantphys.info/plant_biology/labaids/cyanobacteriaslides.shtml http://www.uwsp.edu/biology/courses/botlab/Lab20a.htm

16. Algae is also intentionally cultivated, supporting a multimillion dollar international industry

18. Design Criteria For Algae Reactor • Simple • Passive • Relatively efficient • Movable • Exploit a natural ecosystem • Turn a waste stream into energy

20. Palate sized for ease of transport with a footprint of 11 square feet Ergonomically accessible for reach with a height of 5 feet Effective surface area of 1320 square feet created by 120 trays spaced one ½ inch apart

21. Cheap durable construction materials Plexi glass for reactor housing Removable screens as scaffolding for algae

22. Hybridization of Existing Technologies

24. Wastewater Treatment Calculations Monod Growth Kinetics With variables of Influent Nitrogen Concentration Reactor Effluent Substrate Concentration Specific Growth Rate Hydraulic Retention Time S=K[(1+bθ)/(θ(Yq-b)-1)] Yielded reactor surface areas smaller than “Dead Zone”

25. Optimal Residence Time of 8 Days

26. Calculation Based on Equal Areas Area of “Dead Zone” 8000 square miles at peak Effective surface area of reactor 1320 Square feet Number of units required for total removal 169 million, Equivalent to 67 square miles of reactors 0.004% of farm land in Mississippi River basin

27. Moving Forward • Create working prototype • Trials with various algae species, light conditions, residence times • Test influent and effluent conditions over long time span • Test reactor algae as fertilizer or product stream • Determine economic viability of reactors • Conduct risk assessment and feasibility studies

28. Questions?

29. References • Size-Dependent Nitrogen Uptake in Micro and Macroalgae, M. Hein, Marine Ecology Press Series Vol. 118, 1995 • Sources and Transportation of Nitrogen in the Mississippi River Basin, D. Goolsby, USGS • Phytoremediation as a Management Option for Contaminated Sediments in Tidal Marshes, V. Bert, Environmental Science Vol. 16, 2009 • Nutrient Uptake in Streams Draining Agricultural Catchments of the Midwestern United States, M. Bernot, Fresh Water Biology Vol. 51, 2006 • Nutrient Removal Potential of Selected Aquatic Macrophytes, K. Reddy, Journal of Environmental Quality Vol. 14, 1985 • Nitrogen and Phosphorus Removal from Urban Wastewater by the MicroalgaScendesmusobliquus, M. Martinez, Bioresource Technology, Vol. 73, 2000

30. Nitrogen and Phosphorus in the Upper Mississippi River: Transport, Processing, and effects on the river ecosystem, J. Houser, Hydrobilogia Vol. 640, 2010 • Nutrient Content of Seagrass and Epiphytes in the Northern Gulf of Mexico: Evidence of Phosphorus and Nitrogen Limitation, M. Johnson, Aquatic Botany Vol. 85, 2006 • Reducing Hypoxia in the Gulf of Mexico: Advise from Three Models, D. Scavia, Estuaries Vol. 27, 2004 • Limnology, Third Edition, R. Wetzel, Academic Press

31. Ecological Stoichiometery in Freshwater Benthic Systems: Recent Progress and Perspectives, W. Cross, Freshwater Biology Vol. 50, 2009 • Postaudit of Upper Mississippi River BOD/DO Model, W. Lung, ASCE • Environmental Biotechnology: Principals and Applications, P. McCarty, McGraw-Hill, 2001 • An economic assessment of algal turf scrubber technology for treatment of dairy manure effluent, C. Pizarro, Biological Engineering Vol. 26, pg. 321-326, 2006 • Removing nitrogen and phosphorus from simulated wastewater using algal biofilm technique, W.E.I. Qun, Front. Environ. Sci. Engin. Vol. 2, pg. 446-451, 2008 • Nutrients in the Nation’s Streams and Groundwater, 1992-2004, Circular 1350, N. Dubrovsky, USGS, 2010. Accessed at: http://pubs.usgs.gov/circ/1350/