VARiON Ammonium, Nitrate and Potassium ISE Sensor | Wastewater Process Monitoring | YSI

June 02, 2014
Digital VARiON® Plus ammonium, nitrate and potassium ISE sensor for use with the YSI IQ SensorNet wastewater process monitoring and control system (

The efficient control of Nitrogen in wastewater systems is possible by making those measurements directly in the wastewater process. The direct ISE measuring technology with the VARiON sensor enables optimization of a plant in respect to process efficiency and energy consumption.

The VARiON Plus 700 Series IQ sensors employ the following features:
Combination measurement - The VARiON sensor can continuously measure ammonium with online compensation of potassium ion interferences by using the potassium ISE. Additionally, you can measure ammonium and nitrate by simply using one sensor.

Measurement/Reference - There is a constant potential with the measuring electrode and the reference electrode. This tension is read as the measured value and prevents interferences.

Matrix adjustment - A matrix effect is caused by all free ions in the wastewater. In general, ions don't act according to their concentration which means the mV signal would be influenced and the end result would be incorrect data. The VARiON sensors can be compensated for this matrix effect. This matrix is unique from site to site so an adjustment can be done by keeping the sensor in process and storing the mV value, taking a physical sample, filtering it and conducting lab analysis and then entering those reference values. Conventional calibration is not recommend because the VARiON is factory calibrated. It can still be calibrated with cal standards but probably won't be necessary.