Undoubtedly the most important practical field of application for industrial photometry. All three of the measuring principles employed by Sigrist are applied here: turbidity, absorption, and fluorescence.
Potable water treatment
The criteria of interest for a given raw water depend on its origin. In the case of surface water, the turbidity value (2) is used to control the amount of flocculant added. Where spring water is tapped, the turbidity and oil trace measurements (1) decide whether the water will be used or discarded, and absorption measurement (3) (SAK) detects colorations and changes in the content of dissolved organic substances invisible to the naked eye. All of these variables are detected with the free-fall flow cell, which avoids contamination problems.
In the case of raw water laden with impurities, flocculation/sedimentation is the crucial treatment step for eliminating solids. So the turbidimeter (4) operating between the settling tank and sand filtration is a key contributor to optimal plant operation.
At the sand filters, turbidity measurement (5) not only monitors the filtration step, but also helps optimize the sand purging process.
Finally, UV absorption measurement handles several different functions. It is used following the ozone generators to check the concentration of the generated ozone in the gas phase (9) and following the reactors (8) to detect the residual content. At the outlet of the activated charcoal filters (10) it monitors the organic substances.