Submitted to: Journal of Contaminant Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2001
Publication Date: December 1, 2001
Citation: Hunter, W.J. 2001. Use of vegetable oil in a pilot-scale denitrifying wall. Journal of Contaminant Hydrology. 53(1-2): 119-131. Interpretive Summary: Nitrate contamination of drinking water is a common water quality problem in agricultural areas and can result from operations that involve nitrogen fertilizers or manure. My research shows that innocuous vegetable oils can be used to remove nitrate from groundwater. When oil is applied to soil it becomes trapped in and around the soil particles where it stimulates microorganisms to convert the nitrate to harmless nitrogen gas. Laborator studies show that water containing nitrate is cleansed of nitrate as it is pumped through a permeable barrier of sand containing trapped oil. Innocuous vegetable oil provides a simple method for removing nitrate from flowing water. In situ applications might involve the injection of oil into an aquifer to remove nitrate form groundwater to provide nitrate-free water to a down-stream well.
Technical Abstract: Nitrate in drinking water is a health hazard. Barriers containing innocuous oils can remove nitrate from groundwater. For this study a sand tank containing 344 kg of sand was used as a model of a naquifer. An area near the center of the tank contained 153 kg of sand coated with 1.53 kg of oil served as the barrier. Water containing 20mg L-1 nitrate-N was pumped through the barrier at a rate of 1,139 L wk-1 for 33 weeks. During the 33-week study 257 g of nitrate-N was removed from the water, about 34% of the total present. Barriers could be used to protect groundwater from nitrate contamination or to treat contaminated water. Under in situ conditions such barriers might be effective at removing nitrate for many years.