Spectral in-situ analysis of NO2, NO3, COD, DOC and TSS in the effluent of a WWTP.
An in-situ UV spectrometer was applied to the effluent of a WWTP in Switzerland and calibrated using a multivariate calibration algorithm based on PLS regression. Except for nitrite, the calibration was based on comparative measurements of the effluent in the plant laboratory. Samples made of stock solution added to three different matrices prepared in the EAWAG laboratory were used for the nitrite calibration because the effluent concentrations were always in the range of 0.06-0.26 mg/l. The results show very good precision for nitrite and nitrate. The measuring range for COD and DOC was not completely covered by the measurements, so the meaningfulness of the results is limited. Nevertheless the precision obtained for soluble COD is high enough for most applications at WWTPs. The accuracy of the TSS measurement is unsatisfactory as regards effluent limits since the spectrometer used does not cover the wavelength region up to 700 nm, which gives better signals for TSS calibration due to its strong correlation with turbidity.
Rieger
L
L
EAWAG, Swiss Federal Institute for Environmental Science and Technology, CH-8600 Duebendorf, Switzerland. leiv.rieger@eawag.ch
Langergraber
G
G
Thomann
M
M
Fleischmann
N
N
Siegrist
H
H
D000465:Algorithms; D002138:Calibration; D002244:Carbon / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D009566:Nitrates / Q000032:analysis*; D009569:Nitric Oxide / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D009584:Nitrogen / Q000737:chemistry; D012815:Signal Processing, Computer-Assisted; D013053:Spectrophotometry; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods; D014867:Water; D014873:Water Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis; D014876:Water Pollution; D018508:Water Purification
D009566:Nitrates; D009573:Nitrites; D014873:Water Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; D009569:Nitric Oxide; D002244:Carbon; D009584:Nitrogen