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Continuous monitoring of ammonia in water and wastewater streams is becoming increasingly important for plant operations and process control. Unfortunately, on-line ammonia monitors are generally very expensive, complex, and labor intensive instruments. Most are automated versions of ammonia selective ion electrodes methods better suited to laboratory measurements. Others are automated colorimetric devices or instrumental methods that are difficult to justify on a cost basis.

ATI has developed a completely new approach to on-line monitoring of ammonia that is far less expensive and much simpler than conventional monitoring equipment. The Q45N Dissolved Ammonia Monitor uses reaction chemistry that converts ammonia in solution to a stable monochloramine compound equivalent in concentration to the original ammonia level. The chloramine concentration is then measured with a unique amperometric sensor that responds linearly to chloramines while eliminating interference from excess free chlorine in solution.

Q45N monitors are available in two versions, one that includes all components conveniently integrated into a Nema 4X fiberglas enclosure, and a second that separates the monitor from the chemistry system for applications where a more convenient display location is desired. A sample inlet filter assembly attached to the side of the enclosure allows filtered sample to be drawn from the inlet flow. Sample must be pumped to the inlet assembly at a rate high enough to insure the desired response time for the measurement system. Excess sample is bypassed to any convenient drain location.

ATI’s Q45N monitoring package for dissolved ammonia provides the measurement stability needed to avoid complicated automatic calibration systems. Unlike typical ammonia SIE sensors subject to significant drift problems, the amperometric sensor provides excellent repeatability long periods of time. And because the measurement utilizes chloramine conversion for measurement, the sample is inherently subjected to biocidal conditions, eliminating long term biofouling on the sensor.