Development of a near-real-time analytical system for measurement of N-nitrosamines in water reuse

Trace organic compounds are a major challenge for water reuse. N-nitrosamines and NDMA in particular are of concern because they occur in treated wastewaters at levels closest to those of potential human health concern. These are formed as a disinfection byproducts (DBPs) in treatment processes used in water recycling. NDMA limits and monitoring requirements are included in most permitting requirements for potable reuse plants in the U.S. This proposed project addresses the need for a fast and reliable analytical method for N-nitrosamines for potable reuse water. The technique is capable of online, fully automated operation and cost will be a fraction of the current commonly used laboratory technique, while having equivalent or better measurement performance and speed. The basic scientific principles have been proven and published in a series of scientific papers. Phase I delivered two prototype systems that functioned as required and demonstrate excellent measurement sensitivity and specificity. This Phase II development project includes extending the lower detection limit further into the range needed by regulations and fully automating several functions that will allow continuous, unattended operation. These include initial sample introduction from the production pipeline, reagent addition for sample preparation, and performance of the daily calibration routine. Project consultant, Dr. Shannon Roback has validated this technology at bench-scale during a two-year trial at the largest potable water reuse plant in the world, Orange County Water District, and also worked with a prototype online unit. Advanced water treatment facilities are the ideal target for this analytical system, with over 100 new potable reuse plants in planning (where NDMA monitoring is regulated), in addition to 600 existing reuse plants, and another 675 reuse plants in planning. Many of the US's 52,000 drinking water treatment plants monitor for N-nitrosamines as well. The pharmaceutical, food and beverage industries have more recently identified NDMA contamination as a significant concern. Compared to traditional analytical methods (mass spectrometry, MS), the technique used in the proposed system has already been shown to have equivalent or better sensitivity, with potential for even lower detection limits to be investigated. Analysis time will be significantly less than MS, will not require highly skilled staff, will use much smaller sample and reagent volumes, and the capital cost of equipment will be approximately $100k compared to roughly $400K. Besides facilitating safe water treatment to benefit the environment, this technique uses significantly less toxic solvent for sample extraction and minimal other reagents.