Stream Denitrifying Biofilm

1. Marissa Duff, Molly Julian, Elizabeth Sabol Advisor: Dr. Justin Barone What is a Biofilm? How is the Solution Obtained? • Cluster of microorganisms that form as long as water, nutrients, and a surface are available Step 1 Step 2 P. Alcaligenes Moraxella P. Picketti Denitrificans A. Radiobacter Stream Denitrifying Biofilm Example of a biofilm used for wastewater treatment (Wichern et al., 2008) Graph showing the concentration of nitrate diffusing into the biofilm based on a series of Reynolds Numbers and five different user-chosen column lengths. What is Denitrification? • The process of fixing nitrate and other nitrogen components into atmospheric nitrogen is shown in the following formula: • 24NO3- + 5C6H12O6 12N2 + 24HCO3- + 6CO2 + 18H2O Graph showing the reduction rate of nitrous oxide per gram of biofilm based on carbon concentration as well as five common denitrifiers. Step 4 Step 3 Why a Denitrifying Biofilm? • Nutrient pollution is one of the major causes of water degradation in the United States • High levels of nitrate in streams can negatively affect ecosystem health; if not treated, it can cause health problems in humans (Johnson, 2001) • Best Management Practices (BMPs) are used as preventative strategies, wastewater treatment options offer remediation options; few solutions include a combination of these two technologies Ratio to obtain the mass of biofilm needed based on the reduction ratio found in step two and the conversion from nitrous oxide to nitrate. Graph showing the cross-sectional area needed for the biofilm based on the mass of the biofilm obtained in step three and the user-chosen column length. The size of the biofilm is now known. The final design and placement of the biofilm. The actual structure (left) can be designed based on the stream characteristics, making sure to remain perpendicular to flow with multiple layers. The biofilm (right) should be implemented in conjunction with a riparian buffer strip to help filter sediment and nutrients before entering the stream. People, Prosperity, and the Planet Water outflow People: Our proposed design represents a natural nitrate reduction system for protecting the health of people and their water Prosperity: The main components can be found on-site, reducing initial cost of set-up and construction Planet: A riparian zone and manmade biofilm combination makes efficient use of soils , plants, bacteria, sediment, and stream flow. Final Design: NO3- Source Water inflow Agricultural land, etc. riparian zone stream References: Johnson, S. R. 2001. Iowa Fact Sheet - The nitrogen cycle. Ames, IO: Iowa State University. Wichern, M., C. Lindenblatt, M. Lubken, and H. Horn. 2008. Experimental results and mathematical modeling of an autotrophic and heterotrophic biofilm in a sand filter treating landfill leachate and municipal wastewater. Water Research (42): 3899-3909.