We report on the development of infrared sensor for monitoring of nitrogen as nitrate, nitrite and ammonia in municipal wastewater. To overcome the challenge of strong absorption of the infrared radiation in water, the radiation is transmitted through a waveguide in contact with water rather than through water itself, implementing an attenuated total reflection (ATR) mechanism. Infrared spectroscopy is a powerful tool for identification and quantification of functional molecular groups. Introduction of QCLs reduces the reliance on bulky Fourier Transform Infrared (FT-IR) spectrometers that are sensitive to vibrations and enables development of versatile, portable instrumentation. Efficient nitrogen removal is one of the key objectives of any municipal wastewater treatment operation, yet today, nitrogen is monitored through grab-sampling and sending samples to laboratories for analysis. The sensor will enable reliable, real-time, unsupervised sensing in harsh environment.
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