Spectral UV Sensors for Industrial Waste Water Applications

Continuous or online effluent monitoring is becoming more and more important in Vietnam. The Vietnamese Decree 38/2015/ND-CP requires that every industrial zone or factory located outside of an industrial zone with an effluent volume of more than 1000 m3/day has to monitor continuously the three mandatory parameters COD, TSS and pH at the effluent of the waste water treatment plant.

In Europe in the early 2000 years online spectral UV-VIS sensors were developed by Xylem measuring full absorption spectra in the wave length range of 200-720 nm. These sensors are using calculation algorithms based on multivariate methods for measurements of COD, nitrate and nitrite, in the influent, the biological tank as well as in the effluent of municipal waste water treatment plants.

These types of spectral sensors helped to reduce initial investment costs as well as maintenance efforts to a minimum compared to wet-chemistry analysers. Additionally they showed more accurate results and better correlations to lab standard COD measurements compared to single wave length based sensors, also under changing matrix conditions of the sample.

Two continuously measuring spectral UV-VIS sensors were tested for one month at the effluent channels of two typical Vietnamese industrial zones. Readings of the sensors were compared with the laboratory COD standard test method SMEWW 5220.C:2012 and showed accuracies of ±10% or ±5 mg/l (whichever is higher) after performing a site specific two point user calibration. This study demonstrates that spectral sensors with calculation algorithms originally designed for municipal waste water could be successfully used for two typical Vietnamese industrial waste water applications and … contact us for more.