A Low Cost UV Raman Instrument Measuring Nitrate and Nitrite for Improved Operation and Control of Nitrification/ Dentrification Treatment Processes

Photon Systems, Inc., will develop a unique, online, in situ autonomous monitoring and process control system that will improve the reliability and performance of wastewater treatment systems designed to remove nitrogen through simultaneous nitrification and denitrification. A key technology component of this innovative process control system will be an analytical instrument based on deep ultraviolet resonance Raman (UVRR) spectroscopy, which will measure nitrate and nitrite concentrations in biological nutrient removal system reactors without the need for sample handling, reagent additions, or complex calibration procedures. Detection limits for the proposed instrument are expected to be below about 2 ppb for nitrates and nitrites. Deep UVRR spectroscopy, appropriate for measuring nitrate and nitrate samples, has several advantages over normal Raman spectroscopy. First, excitation at 224 nm provides roughly 150 times the signal enhancement over normal Raman spectroscopy conducted at 785 nm. Second, when excitation occurs within an electronic absorption band of the target material, a resonance effect provides up to eight orders of magnitude of additional signal enhancement. Third, background fluorescence from samples of complex, composite materials are eliminated because no materials are known to fluoresce at wavelengths of less than about 270 nm, whereas all of the Raman spectral information from a 224 nm excitation occurs at wavelengths of less than 245 nm. The proposed instrument uses a unique deep UV laser technology with a 224 nm emission wavelength and subminiature Raman analysis detection methods to make a very inexpensive, miniature (less than 4 L), lightweight (less than 5 lbs), low power consumption (less than 5 W) instrument that can be used in situ for autonomous measurements in harsh environments. The size, weight, and power consumption specifications are for the complete instrument, including lasers, detectors, and all power supplies and controllers. The important commercial applications of this new technology include: (1) in situ monitoring and control of small decentralized membrane bioreactor satellite wastewater treatment systems producing reclaimed water for local reuse; (2) retrofitting existing wastewater-treatment plant process control systems to improve energy efficiency and treatment efficiency; and (3) cost-effective and energy-efficient treatment of high nitrogen-containing side streams in wastewater treatment plants such as digester supernatant and centrate or filtrate. The proposed instrument technology also is valuable for in situ, autonomous, environmental monitoring of air, water, and soil as well as a wide range of commercial, industrial, and medical applications.