Calibration of UV/Vis spectrophotometers: A review and comparison of different methods to estimate TSS and total and dissolved COD concentrations in sewers, WWTPs and rivers

Lepot, Mathieu; Torres, Andrés; Hofer, Thomas Franz; Caradot, Nicolas; Gruber, Günter; Aubin, Jean-Baptiste; Bertrand-Krajewski, Jean-Luc

doi:10.1016/j.watres.2016.05.070

Cited by 73 publications

(46 citation statements)

References 29 publications

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“…Caradot et al (2015) suggested that calibration should be based on at least 15-20 samples, covering for the most part the variation in concentration of the substance measured. There are several procedures for calibration; Lepot et al (2016) used SLR, which has proven a robust and applicable tool. Our results show that if sufficient accuracy in sensor NOx-N results is not achieved by simple correction, an MLR including OC data can be applied to achieve a more accurate correction.…”

Section: Discussionmentioning

confidence: 99%

Organic carbon causes interference with nitrate and nitrite measurements by UV/Vis spectrometers: the importance of local calibration

Uusheimo

Tulonen

Арвола

et al. 2017

Environ Monit Assess

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Compared with sporadic conventional water sampling, continuous water-quality monitoring with optical sensors has improved our understanding of freshwater dynamics. The basic principle in photometric measurements is the incident light at a given wavelength that is either reflected, scattered, or transmitted in the body of water. Here, we discuss the transmittance measurements. The amount of transmittance is inversely proportional to the concentration of the substance measured. However, the transmittance is subject to interference, because it can be affected by factors other than the substance targeted in the water. In this study, interference with the UV/Vis sensor nitrate plus nitrite measurements caused by organic carbon was evaluated. Total or dissolved organic carbon as well as nitrate plus nitrite concentrations were measured in various boreal waters with two UV/Vis sensors (5-mm and 35-mm pathlengths), using conventional laboratory analysis results as references. Organic carbon increased the sensor nitrate plus nitrite results, not only in waters with high organic carbon concentrations, but also at the lower concentrations (< 10 mg C L) typical of boreal stream, river, and lake waters. Our results demonstrated that local calibration with multiple linear regression, including both nitrate plus nitrite and dissolved organic carbon, can correct the error caused by organic carbon. However, high-frequency optical sensors continue to be excellent tools for environmental monitoring when they are properly calibrated for the local water matrix.

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Section: Discussionmentioning

confidence: 99%

Organic carbon causes interference with nitrate and nitrite measurements by UV/Vis spectrometers: the importance of local calibration

Uusheimo

Tulonen

Арвола

et al. 2017

Environ Monit Assess

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“…For monitoring the quality of water in different areas and conditions, UV/Vis spectrophotometers have been widely used. As per the reported study [22], for a certain water matrix, a number of methods have been evaluated and UV/Vis spectrophotometers have provided local and global calibration [22]. The research has concluded that the local calibration is very much preferable and accurate [22].…”

Section: Uv/v Is Spectrophotometersmentioning

confidence: 90%

Physical and Soft Sensor Technologies for Wastewater Quality Management

Mamat¹,

Ramli²,

Abdullah³

et al. 2018

IJEME

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Physical sensors are used mostly to detect sludge and odour in wastewater. Black box modelling or dataderived model using the correlation of input-output parameters is the preferred method as we have assessed. This is due to the non-complex approach of such models as opposed to model-driven, mechanistic models. The latter is hard to be adopted for soft-sensor development due to the inherent complexities and uncertainties. The commonest methods for soft sensor model development are ANN and ANFIS. Many other improvements of these methods are achieved by combining with other techniques to enhance the prediction performance of the soft sensors. Accuracy and precision of data collected for soft sensor modelling has become a vital concern at present to ensure the reliability of wastewater quality indices predicted by the soft sensors. Reduction of the level of reliability of the sensor system in monitoring and controlling of WWTPs would lead to serious lapses in the wastewater quality management. In this backdrop we recommend SEVA soft sensor as one of the best potential solutions which could be offered by the existing technologies.

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“…COD, and BOD5), in online and real-time modes (Carstea et al 2016;Chen et al 2019). These measurements have been proved to be innovative and effective for monitoring wastewater influent quality and providing online early warning for timely precautions (Lepot et al 2016;Michael-Kordatou et al 2015). However, the measuring precision of these pollutants is limited.…”

Section: Introductionmentioning

confidence: 99%

Effect of Dilution on the Pollutant Monitoring in Decentralised Treatment Facilities Using Electrical Conductivity Sensors: Experimental and Modelling Insights

Qian

Liu

Liang

et al. 2021

Preprint

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Electrical conductivity (EC) is a common and cheap water monitoring sensor, and in some way reflects the water body pollution level qualitatively. In this study, the domestic sewage characteristic analysis for decentralised treatment facilities in plain and mountainous rural areas, Eastern China, showed that influent TN/NH3-N/TP concentrations were strongly and linearly correlated with influent EC values. EC source apportionment indicated that although no single ion in rural domestic sewage dominated the EC value, EC was packed with vast amounts of information on pollutant content and colud be precisely predicted by support vector machine (SVM) regression model (R = 0.9520). According to field investigation and dilution simulation analysis, the mechanism of correlations between influent TN/NH3-N/TP concentrations and EC values was confirmed and attributed to dilutions by background water during pipeline transport. Particularly, although the dilution processes in plain and mountainous areas were similar and the dilution coefficients were speculated to both obey a Poisson distribution, the average dilution coefficient in plain area was 0.35 ± 0.16 with λ=4 while that in mountainous area was 0.23± 0.15 with λ=2. Our results demonstrate that the EC sensor provides a cheap, rapid and reliable alternative pollutant monitoring method for decentralised treatment facilities in rural areas with mechanism clear.

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Calibration of UV/Vis spectrophotometers: A review and comparison of different methods to estimate TSS and total and dissolved COD concentrations in sewers, WWTPs and rivers

Cited by 73 publications

References 29 publications

Organic carbon causes interference with nitrate and nitrite measurements by UV/Vis spectrometers: the importance of local calibration

Organic carbon causes interference with nitrate and nitrite measurements by UV/Vis spectrometers: the importance of local calibration

Physical and Soft Sensor Technologies for Wastewater Quality Management

Effect of Dilution on the Pollutant Monitoring in Decentralised Treatment Facilities Using Electrical Conductivity Sensors: Experimental and Modelling Insights

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