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How measuring ammonia with fluorescence is trialled as a world first

Abstract

The Smarter Catchments Project for A UK Water Company is a trial project for the Environment Act 2021. It provides a milestone solution for measuring ammonium more accurately, with less maintenance and more cost effectively. RS Hydro was contracted to provide 2 EasyProbe 30's with turbidity, DO, pH, temperature and ammonium/ammonia and a Proteus plus BOD/COD/TOC/DOC/E. coli/E.Cocci. In addition, RS Hydro are calibrating the instrument for optical ammonium, Total P and Ortho P. Furthermore, a pumped sampling system with telemetry was used with another supplier's sonde. Ammonium ISEs pose the largest issue for monitoring under the Environment Act in terms of reliability, accuracy, maintenance and cost. RS Hydro demonstrated that moving to optical will eradicate all these issues.

Equipment Used

2 EasyProbe 30's, 1 Proteus, 1 pumped flow cell kiosk, 4 telemetry systems, remote support and installation.

Key Points

A world first for measuring ammonium optically using fluorescence.
Only project in the world that only requires ammonium sensor calibrating every 12 months.
RMSE of 0.026mgl

Solution

Here is a graph of the calibration plot of the optical ammonium sensor against the installed ISE which was proven not to have drifted during this period. Please note that the graph represents 1990 data points without a single erroneous value! The RMSE for this data is just 0.026mgl! All manufacturers of ISEs have a stated accuracy of +/-2mgl. This clearly demonstrates the potential accuracy of fluorescence to measure ammonium more accurately than ISEs.

All data will be linked to a database via an API plug in and could be used like the H2NOW project RS Hydro installed in Chicago in 2020. Click here for a video that explains how and why coliform data is more relevant as a river health indicator.

The project provides a milestone solution for measuring ammonium more accurately, with less maintenance and more cost effective.

All of the probes were installed in February 2023 and have provided 15-minute continuous data 24/7 without any data gaps since installation. The maintenance they have had since then has been routine ammonium ISE calibrations every 6 weeks, pH/ORP calibration every 3 months, turbidity at 6 months (Aug 23) and fluorometers every 12 months (which provide BOD/COD/TOC/DOC/E. coli/ammonium/ Total P/Ortho-P).