Integrated controller with up to 2 measuring channels and digital Memosens
- Monitoring of nitrite in drinking water
- Quality control of raw water for the food industry
- Monitoring of nitrite in mineral water batch processes
Colorimetric measuring principle
- Easy upgrade to measuring station by connecting with up to four Memosens sensors
- Automatic calibration and cleaning
- Cooled version for longer reagent shelf life
- Digital communication for remote access
- Two-channel device available
- Digital fieldbuses (Profibus DP, Modbus TCP, Modbus RS485 and Ethernet IP) and web server
After application-specific sample preparation, some of the permeate is pumped into the mixing/
reaction chamber. The specific color reagent is metered exactly in a defined mixture ratio. The
chemical reaction causes the characteristic change in the color of the sample. The multispectral
photometer measures the level of absorption by the sample or the stain solution at defined
wavelengths. The analyzed wavelengths, and their relationships to one another, are parameter-
Based on proportionality the amount of light absorption is a direct indicator of the concentration of
the parameter under analysis in the sample. To compensate for any interference influences resulting
from turbidity and fouling, as well as from the deterioration and aging of the LEDs, a reference
measurement is performed before the actual measurement. This reference signal is subtracted from
the measuring signal. The temperature in the photometer is kept constant to ensure a reproducible
reaction that takes place with a short period of time.
Nitrite is an intermediate stage of the bacterial oxidation of proteins and urea to ammonium and nitrite, and ultimately to nitrate.
Therefore nitrite in the WWTP outlet or drainage canal is an indicator of incomplete nitrification.
Nitrites are often used as a corrosion inhibitor in process water and cooling water. The food industry
uses nitrite as a preservative (e.g. curing salt). Nitrite rarely occurs in surface water as it is easily
oxidized to nitrate in the air. Therefore, online nitrite measurement is particularly performed in
areas with reduced oxygen content, such as well water and areas with low flow. Due to its toxicity, no
nitrite is permitted in drinking water. (For example, the limit at the water treatment outlet is 0.1
mg/l (0.1 ppm) according to the 2011 German Drinking Water Regulation). Nitrite causes the
conversion of hemoglobin to methemoglobin, which decreases the ability of the blood to carry
oxygen ("internal asphyxia").