Application of tracer technology in wastewater treatment processes: a review

Residence Time Distribution: Literature Survey, Functions, Mathematical Modeling, and Case Study—Diagnosis for a Photochemical Reactor

“…The procedure was extensively described by Octave Levenspiel [44]. However, there are still issues related to the type of the tracer, how it is inserted into the flow, the vessel boundaries, and how its signal is detected and eventually converted to finally plot the concentration vs. time curve (the C-curve) [7,[45][46][47][48]. In brief, the tracer methodology is an experimental procedure that introduces a known amount of tracer into a system and measures its concentration over time at different points (most commonly at the exit).…”

“…Moreover, the tracer must be detectable at very low concentrations, and the measurement technique must be sensitive and accurate. Since the tracer method is applied in various domains [11], including chemical engineering [3], environmental engineering [46], metallurgy [49], hydrology [48], pharmaceutics [5,50], medicine [51], and many others, there is a large variety of tracers such as electrolytes, dyes, stable or radioactive isotopes, [52] and others [3]. Conductivity, fluorescence, color, X-ray emission, or even temperature are among the properties that allow tracer detection, and most of the time, calibration curves are used to convert a specific property into tracer concentration.…”