You probably know that UV254 analyzers are used to determine the power needed by UV disinfection systems to satisfactorily disinfect water but did you know that…
…UV254 analyzers are a fantastic surrogate for TOC analyzers at a fraction of the cost to buy and own?
…UV254 monitors are fabulous THM and disinfection by product predictors?
…UV254 absorbance monitors are extremely useful in determining coagulant dosage?
UV254 Absorbance and Transmittance
The UV254Sense is an optical technology, that greatly reduces drift due to variations in the light source and therefore requires no zero. An ultraviolet light source at 254nm is shone through the sample depending on water chemistry for the amount that makes it to the other side is measured at a detector. This can be expressed as UVT (Ultraviolet Transmission) or UVA (Ultraviolet Absorbance), two values that are mathematically related.
The amount of UV254 that is absorbed is due, in large part, to the organics in the water. The same organics that make up a large part of the TOC, or the coagulant demand of that water.
UV254 as part of a coagulation control program
Coagulation dose is in large part dependent on pH, turbidity, temperature, alkalinity and organics loading. Depending on water chemistry, for many plants the largest determining factor is the organics load and a feed forward control based on organics loading or UV254 absorbance provides a robust coagulation control system that can be further enhanced with feedback from a streaming current analyzer.
UV254 as a surrogate for TOC analyzers
Conventional online TOC monitoring is expensive, requires reagents and extensive maintenance and a degree of specialist expertise that can be absent from treatment works. Most TOC measuring applications can be met using a far cheaper, easier, less maintenance intensive online UV254 analyzer. A simple linear correlation between TOC and UV254 can be built allowing the UV254Sense to output TOC directly in ppm or mg/l.
UV254 as a predictor for Tri Halo Methanes (THMs) and Disinfection By-Products (DBPs)
UV254 is absorbed most strongly by the same aromatic organics that bind with chlorine to form the THMs and DBPs that are of such concern. By monitoring the incoming and outgoing water from a water treatment plant the water process engineer can monitor how well the process is removing THM and DBP precursors.