|
|
Type of Document Master's Thesis Author Daily, Brenda Lynn Author's Email Address bread@nd.edu URN etd-10012007-120606 Title Stimulating Denitrification in Agricultural Headwater Streams Using Elemental Sulfur Degree Master of Science in Environmental Engineering Department Civil Engineering and Geological Sciences Advisory Committee
Advisor Name Title Dr. Robert Nerenberg Committee Chair Dr. Jennifer Tank Committee Member Dr. Stephen Silliman Committee Member Keywords
- elemental sulfur
- denitrification
Date of Defense 2007-10-11 Availability restricted Abstract The extensive use of fertilizers in agriculture has led to widespread eutrophication. In this thesis, I explored sulfur-based autotrophic denitrification in agricultural headwater streams as means to remove nitrogen before it impacts receiving waters. I studied a stream mesocosm, simulating a headwater drainage ditch, amended with elemental sulfur. Nitrate removal efficiencies were as high as 99%, corresponding to effluent concentrations below 1 mg/L NO3--N. However, nitrate removals decreased over time, concurrent with accumulation of biomass on the bed surface, probably phototrophic growth. A model was developed to describe the hydraulic and biological reactions taking place within the mesocosm. The model captured trends in bulk liquid nitrate concentrations, but provided reasonable accuracy only when a high diffusive exchange coefficient was used. This suggests advective exchange with the bulk may be significant. Microbial community analysis of the sulfur-oxidizing biofilm suggested significant bacterial diversity existed within the mesocosm, with little variation in depth.Files
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access Read-Daily_Thesis.pdf 1.15 Mb 00:05:20 00:02:44 00:02:24 00:01:12 00:00:06 indicates that a file or directory is accessible from the campus network only.