Abstract:
Although near infrared (NIR) spectroscopy has been evaluated for numerous applications, the
number of actual on-line or even on-site industrial applications seems to be very limited. In the
present paper, the attempts to produce on-line predictions of the chemical oxygen demand (COD)
in wastewater from a pulp and paper mill using NIR spectroscopy are described. The task was
perceived as very challenging, but with a root mean square error of prediction of 149 mg/l,
roughly corresponding to 1/10 of the studied concentration interval, this attempt was deemed as
successful. This result was obtained by using partial least squares model regression, interpolated
reference values for calibration purposes, and by evenly distributing the calibration data in the
concentration space. This work may also represent the first industrial application of on-line COD
measurements in wastewater using NIR spectroscopy.
