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

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.