Automated, online nitrogen analyzer

The presence of these excess nutrients in natural waterways leads to algal blooms that threaten thelife of aquatic organisms and human drinking water sources. Algal blooms not only reduce theoxygen content in water but also produce toxins that are difficult to remove and harmful to health.A key nutrient is nitrogen an estimated one-hundred billion kilograms of which is releasedannually from fertilizers around the world. Municipal and industrial wastewater treatment processesexpend significant effort and energy reducing nitrogen content. Traditionally nitrogen is removedthrough a nitrification/denitrification process. Microorganisms first convert ammonia to nitratethrough hydroxylamine and nitrite followed by an organic reduction of nitrate to dinitrogen. Thisprocess requires oxygen making it energy intensive.Modern wastewater treatment systems are based on an anaerobic ammonium oxidation("anammox") process. This process by-passes multiple steps in the traditional treatment method bydirect conversion of nitrite and ammonium to dinitrogen allowing for the optimized formation ofbiogas.Our proposal is focused on using surface-enhanced Raman spectroscopy to measure the nitrogencycle quantitatively in municipal wastewater with a near-term focus on ammonia andhydroxylamine two key process indicators for the anammox process. Colorimetric methods foranalysis are easily influenced by sample color or matrix interferences while laboratory methodslike ion chromatography are complex and expensive. Our approach addresses these challengesproviding an automated semi-continuous instrument for nitrogen concentration. Our technologywill improve energy efficiency and support renewable energy generation in the wastewatertreatment process through improved process monitoring and control.