Skip to content

Online water quality monitoring and process control using UV-Vis sensors

Feb 28, 2022 | 4 min read time by Z Shi

First published in Water e-Journal Vol 7 No 1 2022.


Research Questions

  • Why and how suspended particles in the water affect water quality measurements using online UV-Vis instruments?
  • How to eliminate particle interference and obtain accurate measurements of UV254 using online UV-Vis instruments?
  • Can we use UV-Vis spectra directly or indirectly for water treatment process control?


  • Provide in-depth knowledge of the impact of suspended particles on online UV-Vis measurements.
  • Develop software compensation techniques to improve online measurement.
  • Develop models using spectra information to predict chemical dosing for water treatment process control.

Findings to date

  • New knowledge added in understanding the effect of particle type and concentration on UV-Vis measurements and the compensation techniques.
  • A universal compensation algorithm has been developed with better accuracy compared with the generic algorithm which has suffered from undercompensated or overcompensated measurements in some cases.
  • Confirmed the use of single wavelength compensation with similar accuracy compared with the multiple wavelength compensation for online instruments as built-in compensation algorithms.


  • Simple UV–Vis instruments with a single wavelength could be employed in the field to monitor water quality.
  • Chemometric models based on UV-Vis spectra can be developed into decision support tools for water treatment process control.