Long-term evaluation of a spectral sensor for nitrite and nitrate.
A spectral in-situ UV sensor was investigated to measure nitrite and nitrate concentrations in the effluent of the EAWAG pilot-scale plant. The sensor was used with a calibration that was based on data from another WWTP and was operated over a period of 1.5 years. The results showed constant accuracy although the sensor was operated with minimal maintenance (manual cleaning once a month). It could be shown that the sensor was able to accurately predict the nitrite and nitrate concentration with a precision of 0.32 mg N/l (95% prediction interval at mean lab value of 1.15 mg N/l) and 1.08 mg N/l (at 5.55 mg N/l) for nitrite and nitrate, respectively. The UV sensor showed good results for nitrite in the low concentration range and very accurate results for higher concentrations (up to 10 mg N/l). This allows using the sensor for alarm systems as well as for control concepts at WWTPs.
Rieger
L
L
Département de génie civil, Pavillon Pouliot, Université Laval, Québec, QC, Canada. leiv.rieger@gci.ulaval.ca
Vanrolleghem
P A
PA
Langergraber
G
G
Kaelin
D
D
Siegrist
H
H
D002138:Calibration; D004784:Environmental Monitoring / Q000379:methods*; D009566:Nitrates / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*
D009566:Nitrates; D009573:Nitrites; D014874:Water Pollutants, Chemical