We report on the development of mid-infrared spectroscopy-based sensors for inline water and wastewater analysis. Midinfrared spectroscopy is a powerful tool for chemical identification and quantification. To overcome the limitations of the technique imposed by rapid extinction of the infrared signal in water, we have developed pre-concentration techniques that achieve beyond four orders of magnitude enhancement of measurement sensitivity, along with enhanced selectivity, for analytes. Applications include monitoring of nutrients and metabolites in bioreactor systems for wastewater treatment and industrial processes (e.g. biofuel production), in-line process control in chemical manufacturing, and rapid on-site screening of contaminants in environmental samples for assessment and remediation of environmental contamination sites.
We report on development of a novel type of sensor for in-line analysis of nitrogen-based molecules, such as nitrate, nitrite and ammonia, in municipal wastewater. The sensor utilizes pre-concentration of analytes with ion-selective materials and subsequent optical detection in the mid-infrared spectral range. Advantages of this sensor include in-line autonomous measurements, self-calibration mechanisms and high selectivity to different nitrogen species. The sensor targets implementation at wastewater treatment plants (WWTPs) to enable control and optimization of the aeration process, thereby reducing energy consumption and cost. We will discuss challenges encountered during the transition of the technology from the lab bench to WWTPs, including operational efficiency of the optical sources, such as quantum cascade lasers (QCLs) vs. thermal sources. Extension of the sensor capabilities for sensing of additional contaminants and for bioreactor systems control will be discussed.
Infrared technology can provide a wealth of information related to biological and chemical hazards in the environment. However, this technology mostly exists in the form of bulky instrumentation on optical benches in academic laboratories. We discuss the transition of IR sensing to various points-of-need applications, including food and water safety, bioreactor process control and chemical analysis of drinking water. In particular, in remote locations the access to clean drinking water is critical to soldiers’ health. Mid-infrared spectroscopy is a powerful tool for identification and quantification of a wide range of common organic and inorganic compounds. In this contribution we present data demonstrating proof-of-concept of a quantum cascade laser (QCL)-based infrared sensor for evaluation of toxic industrial chemicals (TICs) and toxic industrial materials (TIMs) and discuss the path for development of miniaturized, point-of-need IR photonic integrated circuits (IR-PIC).
There is a growing demand for hand-held and/or field-grade sensors for biochemical analysis of fluids. These systems have applications in monitoring of nitrogen-based compounds (such as nitrate and ammonia) in the wastewater treatment industry; bacterial detection in drinking water; analysis of biofluids, such as urine or blood; and in many other areas. Mid-infrared (midIR) spectroscopy is a powerful tool for identification and quantification of a wide range of common organic and inorganic compounds. Although IR radiation is strongly absorbed in water, this technology can be adapted for analysis of fluids by utilizing the principles of attenuated total reflection (ATR). In this contribution we highlight the application of IR spectroscopy in wastewater analysis as well as for metabolomic analysis in bioreactors. We discuss the requirements for IR signal stability that are necessary for biochemical analysis of fluids and provide examples of challenges encountered during transition from FTIR to a QCL-based platform. Overall, our stepwise efforts target eventual integration of a QCL light source, waveguide sensor, and IR detector onto a single photonic integrated circuit (PIC) for applications in the defense sector as well as for a broad consumer market.
Monitoring water quality by detecting chemical and biological contaminants is critical to ensuring the provision and discharge of clean water, hence protecting human health and the ecosystem. Among the available analytical techniques, infrared (IR) spectroscopy provides sensitive and selective detection of multiple water contaminants. In this work, we present an application of IR spectroscopy for qualitative and quantitative assessment of chemical and biological water contaminants. We focus on in-line detection of nitrogen pollutants in the form of nitrate and ammonium for wastewater treatment process control and automation. We discuss the effects of water quality parameters such as salinity, pH, and temperature on the IR spectra of nitrogen pollutants. We then focus on application of the sensor for detection of contaminants of emerging concern, such as arsenic and Per- and polyfluoroalkyl substances (PFAS) in drinking water. We demonstrate the use of multivariate statistical analysis for automated data processing in complex fluids. Finally, we discuss application of IR spectroscopy for detecting biological water contaminants. We use the metabolomic signature of E. coli bacteria to determine its presence in water as well as distinguish between different strains of bacteria. Overall, this work shows that IR spectroscopy is a promising technique for monitoring both chemical and biological contaminants in water and has the potential for real-time, inline water quality monitoring.
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