SBIR Phase II: Real-Time Nitrogen Sensor for Wastewater Treatment Optimization

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The broader impact/commercial potential of this Small Business Technology Transfer Research (STTR) Phase II project will be to supply nitrogen sensors for wastewater treatment process control and automation, potentially saving $600 M per year in electric energy for the U.S. municipal wastewater treatment industry. Municipal wastewater treatment processes are based on energy-intensive aeration. Currently, the primary monitoring method is sending “grab-samples” to a lab, with delays in receiving results. By enabling real-time process control of the energy-consuming denitrification process, electric energy usage can be reduced by 20% or more. The economic impact to each municipal wastewater treatment plant is an average energy savings of $200 k per year, with less than 6 months payback, and lower operating costs while reducing/preventing out-of-control effluent events. Competing technologies for real-time nitrogen sensors are limited by poor performance, high maintenance needs, high cost, and reliability problems. The proposed new sensor offers a reliable, cost-effective, low-maintenance alternative with potential applications in direct potable reuse (DPR), and managing environmental water quality in agricultural fertilizer runoff, industrial discharge and feed-lot monitoring. The proposed system will help assure the nation’s clean water supply. In addition, as a platform technology for use in related fields, future applications include industrial sensors for real-time manufacturing process control, homeland security sensing for chemical and biological defense, and biomedical use for point-of-care diagnostics. This STTR Phase II project proposes to develop an infrared-detection sensor for real-time monitoring of nitrogen as nitrate, nitrite, and ammonia in municipal wastewater. The technology addresses strong IR attenuation in water with the first industrial-scale sensor application based on a fiber-optic evanescent wave technique, guiding mid-IR radiation from a tunable quantum-cascade laser through an IR waveguide rather than through the wastewater itself. The incorporation of an ion-exchange material as an encapsulating medium reduces interference and acts as protection against fouling. Novel control algorithms for auto-calibration enable long-term autonomous operation and ensure a reliable signal-to-noise ratio, for 24x7 real-time control of the energy-intensive aeration process. The proposed nitrogen sensor will have a wide range of sensitivity, from 0.1 ppm to 250 ppm, and can be used for other important chemical species with fingerprints in the mid-IR spectral range, such as phosphorus and organic contaminants, making it a robust tool for water quality assessment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.