Nitrate ion is a common measurement in environmental waters, lakes, streams, and rivers along with drinking water and municipal waste water treatment plants. Nitrate ion measurements are useful at several points in a municipal wastewater treatment plant. The Nitrification process oxidizes the toxic ammonia ion into a much less toxic nitrate ion using an aerobic activated sludge process. Next a De-nitrification process reduces the nitrate ion (NO3-) to nitrogen gas (N2) through an anoxic reaction or in a separate anaerobic digester minimizing the nutrient value of the plant effluent.

ECD’s highly intelligent HYDRA Nitrate Analyzer System measures the concentration of dissolved nitrate as nitrogen (NO3–N) in water. The sensor uses two electrodes to determine the NO3–N concentration: a nitrate ion electrode and a chloride ion electrode. The chloride ion electrode provides compensation for the positive chloride ion interference on the nitrate electrode. An optional pH or ammonium electrode can be ordered in the HYDRA-NO3 sensor. While neither of these optional electrodes is required for the Nitrate measurement, the additional process information about the pH or ammonium concentration could be useful.