N. Fleischmann - Academia.edu (original) (raw)

Papers by N. Fleischmann

There is no doubt that respirometry is a useful measurement principle in the field of wastewater ... more There is no doubt that respirometry is a useful measurement principle in the field of wastewater treatment. Although a large variety of methods and case studies have been published, respirometry has become neither a standard tool for control nor for assessment and optimisation of treatment plants. The drawback of the conventional method for determining nitrification kinetics is the long experimental time. This disadvantage can be avoided by “turning over” the experiment. Starting with low ammonia concentrations the steep slope of the Monod curve is measured first. The low concentration branch of the Monod curve is also the part where e.g. inhibition can be detected. Therefore the proposed procedure allows us to speed up the measurement of nitrification kinetics and to measure nitrification inhibition on-line.

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

Alarm parameters are in many ways different from measurements of well defined chemical substances... more Alarm parameters are in many ways different from measurements of well defined chemical substances. Being confronted with an increasing number of potentially harmful compounds as well as financial and logistic constraints, new variables (such as alarm parameters) that allow for an integrated assessment or for a first screening can be a solution. To monitor for surrogate or aggregate variables can be a useful strategy to overcome some of the constraints. It must be conceived that this can go along with losses in terms of comparability of results and even in tailor-made variables. Spectral data and their evolution over time are rich in information and compensate for losses due to aggregation and generalisation. Therefore it can be expected that alarm parameters developed from spectral data are transferable, accurate and selective to an extent which is beyond the state-of-the-art. The paper introduces time-resolved delta spectrometry, a method that was developed to generate alarm parame...

For the protection of bankside wells and a groundwater recharge an early warning system had to be... more For the protection of bankside wells and a groundwater recharge an early warning system had to be developed. The monitoring network design is based on sensor measurements only. For this purpose a new submersible spectrometer has been successfully tested for multi-parameter measurements directly in the medium. The developed system can easily be upgraded with other new sensors. Only calibration and validation data are supplied by conventional grab sampling and laboratory analysis.. A conventional testfilter improved by on-line monitoring at 5 sampling sites serves as a reference system. The whole system is equipped with remote control and the internet serves as the control centre of the network. All measurement data from all 9 sites are available in real time on the internet.

With the release of the EC water framework directive, water quality management will become a tran... more With the release of the EC water framework directive, water quality management will become a trans national issue on a catchment scale, requiring exchange of water quality data between governing boards and water authorities of the different member states. One issue for water quality management is to have sufficient and comparable information about the water quality and the impacting factors and effectiveness of measures taken. Based on novel technologies, a modular monitoring station suitable for continuous application in sewers, wastewater treatment plants and surface water bodies has been designed. The monitoring stations serve as the backbone of a water quality pilot network, that is currently tested at different locations in Austria. The network also includes a central data base server, where the collected data is processed consistently and stored in a standard format. The water quality network design shows new perspectives with respect to continuous and consistent water data co...

A project for optimising the operation of a municipal water treatment plant included the testing ... more A project for optimising the operation of a municipal water treatment plant included the testing of a multi-sensor system for forecasting the pollution load to a treatment plant or its biological unit, using as criteria a fundamentally reliable assessment of pollution levels and the stability of the system over short and longer periods. For the parameters COD and COD f , agreement between calculated and measured data was good, whereas the relationships were less obvious for the parameters NH 4 -N and N total . Generally, correlation was better for the dissolved parameters. Checking the stability of the computed relationship gave satisfactory results for the COD t concentration in the supply line both for measurements carried out immediately following the learning period and for measurements carried out a month later.

Testfilters are a means to imitate elimination processes in riverbank filtration. They give evide... more Testfilters are a means to imitate elimination processes in riverbank filtration. They give evidence about the biodegradability of organic substance in surface waters. Testfilters are used successfully at a couple of waterworks, e.g. on River Rhine and River Elbe, as an early warning system. Disturbances of the elimination process due to substances toxic for the sessile microorganisms can be identified and quantified. The sensitivity of the testfilters depends upon the parameters selected to monitor the organic carbon concentrations. This poster addresses the monitoring of testfilters operated at the River Danube, especially the application of an UV/VIS spectrometer in comparison with standard DOC and TOC analysis.

A submersible UV/VIS spectrometer for in-situ real-time measurements is presented. It utilises th... more A submersible UV/VIS spectrometer for in-situ real-time measurements is presented. It utilises the UV/VIS range (200–750 nm) for simultaneous measurement of COD, filtered COD, TSS and nitrate with just a single instrument. A global calibration is provided that is valid for typical municipal wastewater compositions. Usually high correlation coefficients can be achieved using this standard setting. By running a local calibration improvements concerning trueness, precision and long term stability of the results can be achieved. The calibration model is built by means of PLS, various validation procedures and outlier tests to reach both high correlation quality and robustness. This paper describes the UV/VIS spectrometer and the calibration procedure.

Advanced treatment plant and sewer network control is a promising application of modelling in the... more Advanced treatment plant and sewer network control is a promising application of modelling in the field of urban wastewater management. At the same time there are only vague ideas about the measurement techniques that would be necessary for model based real time prognosis and control. One of he major tasks on the way towards online modelling is the search for and the validation of measurement techniques. An UV/VIS spectrometer (“spectro::lyser”) was successfully used for measuring organic matter at the highly dynamic inflow of a wastewater treatment plant. This poster describes the UV/VIS spectrometer, the calibration procedure and the results obtained.

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

Alarm parameters are in many ways different from measurements of well defined chemical substances... more Alarm parameters are in many ways different from measurements of well defined chemical substances. Being confronted with an increasing number of potentially harmful compounds as well as financial and logistic constraints, new variables (such as alarm parameters) that allow for an integrated assessment or for a first screening can be a solution. To monitor for surrogate or aggregate variables can be a useful strategy to overcome some of the constraints. It must be conceived that this can go along with losses in terms of comparability of results and even in tailor-made variables. Spectral data and their evolution over time are rich in information and compensate for losses due to aggregation and generalisation. Therefore it can be expected that alarm parameters developed from spectral data are transferable, accurate and selective to an extent which is beyond the state-of-the-art. The paper introduces time-resolved delta spectrometry, a method that was developed to generate alarm parame...

Using measurements of the whole UV/VIS spectrum enables to monitor changes in wastewater concentr... more Using measurements of the whole UV/VIS spectrum enables to monitor changes in wastewater concentration as well as in wastewater composition. Operators of wastewater treatment plants benefit when changes of concentration and/or composition of industrial inlets can be detected and therefore a possible failure of the treatment plant performance can be avoided. The instrument used is a submersible UV/VIS spectrometer (spectro::lyser by s::can Messtechnik, Vienna) that utilises the whole UV/VIS range between 200 and 750 nm. With just one single instrument nitrate, organic matter and suspended solids can be measured simultaneously. The spectrometer is installed directly in the process and measures in real-time. It is equipped with a very effective auto-cleaning system using pressured air that enables measurements at the influent of a wastewater treatment plant or directly in the sewer for several weeks (> 4) without maintenance. The paper shows influent measurements at a wastewater tre...

s-can.asia

... THE SUBMERSIBLE SPECTROMETER UV/VIS spectroscopy is a well known and accepted method for BTX ... more ... THE SUBMERSIBLE SPECTROMETER UV/VIS spectroscopy is a well known and accepted method for BTX measurement on higher concentration levels (Rinke and Hartig ... It is a 2-beam 256 pixel UV/VIS spectrometer, with a Xenon lamp as a light source and a path length of 80 ...

Water science and technology : a journal of the International Association on Water Pollution Research, 2003

There is no doubt that respirometry is a useful measurement principle in the field of wastewater ... more There is no doubt that respirometry is a useful measurement principle in the field of wastewater treatment. Although a large variety of methods and case studies have been published, respirometry has become neither a standard tool for control nor for assessment and optimisation of treatment plants. drawback of the conventional method for determining nitrification kinetics is the long experimental time. This disadvantage can be avoided by "turning over" the experiment. Starting with low ammonia concentrations the steep slope of the Monod curve is measured first. The low concentration branch of the Monod curve is also the part where e.g. inhibition can be detected. Therefore the proposed procedure allows us to speed up the measurement of nitrification kinetics and to measure nitrification inhibition on-line.

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

A submersible UV/VIS spectrometer was used to monitor a pilot-scale sequencing batch reactor (SBR... more A submersible UV/VIS spectrometer was used to monitor a pilot-scale sequencing batch reactor (SBR). The instrument utilises the whole UV/VIS range between 200 and 750 nm. With just one single instrument nitrate, organic matter and suspended solids can be measured simultaneously. The spectrometer is installed directly in the reactor, measures in real-time, and is equipped with an auto-cleaning system using pressured air. The paper shows the calibration results for measurements in the SBR tank, time series for typical SBR cycles, and proposes possible ways for optimisation of the operation by using these measurements.

Continuous monitoring of the COD and its fractionation in wastewater is by far no trivial issue, ... more Continuous monitoring of the COD and its fractionation in wastewater is by far no trivial issue, because of the many influences on the measurement quality. Especially in raw wastewater or primary clarifier effluent effects like failure of the probe-sampling or -preparation system, unrepresentative sampling or sensor fouling can lead to substantial errors in the measurement results. A new submersible spectrometer is presented, which utilises the UV-VIS-range (200-750 nm) for simultaneous measurement of COD, COD fractionation, turbidity and nitrate with just one single instrument. The miniaturised spectrometer allows easy installation even in 2" boreholes for groundwater monitoring. It is a sensor installed directly in the process, thus requires no sampling, sample preparation, no reagents and is equipped with an auto-cleaning system. The spectrometer was tested at three different WWTP´s in Austria, Germany and Switzerland. It proved to work extremely reliably even in raw wastewater upstream the screening station and over long periods. The instrument can be calibrated to the measurement location specific wastewater matrices and therefore opens new possibilities with respect to data quality. A validation only of the sensor itself showed that the instrument delivers results with a very good repeatability (mean stddev. = 2.08 mg COD /l, CV = 0.83% of mean value). From field test results the trueness was calculated to zero as the mean of the residuals with a 95%-confidence interval of 13.7 mg COD /l. The precision was ±50-60 mg COD /l (95%-confidence interval for a predicted value). It was concluded that the main influence on the precision are changes of the wastewater matrix changes that are not included in the instrument calibration. The test results clearly indicate that continuous monitoring of COD and its fractionation delivers improved quality of dynamic data compared to discontinuous laboratory analysis. Such data is valuable for dynamic simulation of wastewater treatment plants -especially in case processes are simulated -like excess biological phosphorous uptake -which are strongly influenced by dynamic changes of the concentration of the COD fractions.

Chemie Ingenieur Technik, 2002

Water Science & Technology

A prototype sensing system for in-situ monitoring of volatile organic compounds in contaminated g... more A prototype sensing system for in-situ monitoring of volatile organic compounds in contaminated groundwater was tested at a pilot scale plant. The sensor consists of a commercially available Fourier transform infrared spectrometer, connected to a 6 m long infrared transparent silver halide fibre optic cable. A 10 cm long core-only section at the centre of the fibre is mounted on a sensor head and coated with a hydrophobic polymer layer, while the remaining fibre is protected by Teflon tubing and thus not in contact with the surrounding media. The sensor head was immersed into the monitoring wells of the pilot plant testing the sensor system under circumstances close to field conditions and typical for in-situ measurements. The pilot plant consists of a 1 m3 cubic tank filled with gravel. A pump is used to circulate water horizontally through the tank, simulating a natural aquifer. The evolution of the concentration of analytes injected into the system is monitored with time using th...

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

An in-situ UV spectrometer was applied to the effluent of a WWTP in Switzerland and calibrated us... more 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 du...

Water science and technology : a journal of the International Association on Water Pollution Research, 2002

For the protection of bankside wells and a groundwater recharge an early warning system had to be... more For the protection of bankside wells and a groundwater recharge an early warning system had to be developed. The monitoring network design is based on sensor measurements only. For this purpose a new submersible spectrometer has been successfully tested for multi-parameter measurements directly in the medium. The developed system can easily be upgraded with other new sensors. Only calibration and validation data are supplied by conventional grab sampling and laboratory analysis.. A conventional testfilter improved by on-line monitoring at 5 sampling sites serves as a reference system. The whole system is equipped with remote control and the internet serves as the control centre of the network. All measurement data from all 9 sites are available in real time on the internet.

Water Science & Technology, 2008

The EU-WFD requires certain monitoring tasks, which yet cannot be fulfilled by automated monitori... more The EU-WFD requires certain monitoring tasks, which yet cannot be fulfilled by automated monitoring devices. Nevertheless, the technical progress of recent years allows monitoring station designs, which enable long-term field application under reasonable maintenance demand. State-of-the-art monitoring stations allow the setup and operation of intelligent monitoring networks, which deliver quality proved and utilisable information to the end-user as opposed to a collection of time-series. Based on a full-scale example monitoring station design, long-term observations and possible ways of (automated) data interpretation are discussed.

There is no doubt that respirometry is a useful measurement principle in the field of wastewater ... more There is no doubt that respirometry is a useful measurement principle in the field of wastewater treatment. Although a large variety of methods and case studies have been published, respirometry has become neither a standard tool for control nor for assessment and optimisation of treatment plants. The drawback of the conventional method for determining nitrification kinetics is the long experimental time. This disadvantage can be avoided by “turning over” the experiment. Starting with low ammonia concentrations the steep slope of the Monod curve is measured first. The low concentration branch of the Monod curve is also the part where e.g. inhibition can be detected. Therefore the proposed procedure allows us to speed up the measurement of nitrification kinetics and to measure nitrification inhibition on-line.

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

Alarm parameters are in many ways different from measurements of well defined chemical substances... more Alarm parameters are in many ways different from measurements of well defined chemical substances. Being confronted with an increasing number of potentially harmful compounds as well as financial and logistic constraints, new variables (such as alarm parameters) that allow for an integrated assessment or for a first screening can be a solution. To monitor for surrogate or aggregate variables can be a useful strategy to overcome some of the constraints. It must be conceived that this can go along with losses in terms of comparability of results and even in tailor-made variables. Spectral data and their evolution over time are rich in information and compensate for losses due to aggregation and generalisation. Therefore it can be expected that alarm parameters developed from spectral data are transferable, accurate and selective to an extent which is beyond the state-of-the-art. The paper introduces time-resolved delta spectrometry, a method that was developed to generate alarm parame...

For the protection of bankside wells and a groundwater recharge an early warning system had to be... more For the protection of bankside wells and a groundwater recharge an early warning system had to be developed. The monitoring network design is based on sensor measurements only. For this purpose a new submersible spectrometer has been successfully tested for multi-parameter measurements directly in the medium. The developed system can easily be upgraded with other new sensors. Only calibration and validation data are supplied by conventional grab sampling and laboratory analysis.. A conventional testfilter improved by on-line monitoring at 5 sampling sites serves as a reference system. The whole system is equipped with remote control and the internet serves as the control centre of the network. All measurement data from all 9 sites are available in real time on the internet.

With the release of the EC water framework directive, water quality management will become a tran... more With the release of the EC water framework directive, water quality management will become a trans national issue on a catchment scale, requiring exchange of water quality data between governing boards and water authorities of the different member states. One issue for water quality management is to have sufficient and comparable information about the water quality and the impacting factors and effectiveness of measures taken. Based on novel technologies, a modular monitoring station suitable for continuous application in sewers, wastewater treatment plants and surface water bodies has been designed. The monitoring stations serve as the backbone of a water quality pilot network, that is currently tested at different locations in Austria. The network also includes a central data base server, where the collected data is processed consistently and stored in a standard format. The water quality network design shows new perspectives with respect to continuous and consistent water data co...

A project for optimising the operation of a municipal water treatment plant included the testing ... more A project for optimising the operation of a municipal water treatment plant included the testing of a multi-sensor system for forecasting the pollution load to a treatment plant or its biological unit, using as criteria a fundamentally reliable assessment of pollution levels and the stability of the system over short and longer periods. For the parameters COD and COD f , agreement between calculated and measured data was good, whereas the relationships were less obvious for the parameters NH 4 -N and N total . Generally, correlation was better for the dissolved parameters. Checking the stability of the computed relationship gave satisfactory results for the COD t concentration in the supply line both for measurements carried out immediately following the learning period and for measurements carried out a month later.

Testfilters are a means to imitate elimination processes in riverbank filtration. They give evide... more Testfilters are a means to imitate elimination processes in riverbank filtration. They give evidence about the biodegradability of organic substance in surface waters. Testfilters are used successfully at a couple of waterworks, e.g. on River Rhine and River Elbe, as an early warning system. Disturbances of the elimination process due to substances toxic for the sessile microorganisms can be identified and quantified. The sensitivity of the testfilters depends upon the parameters selected to monitor the organic carbon concentrations. This poster addresses the monitoring of testfilters operated at the River Danube, especially the application of an UV/VIS spectrometer in comparison with standard DOC and TOC analysis.

A submersible UV/VIS spectrometer for in-situ real-time measurements is presented. It utilises th... more A submersible UV/VIS spectrometer for in-situ real-time measurements is presented. It utilises the UV/VIS range (200–750 nm) for simultaneous measurement of COD, filtered COD, TSS and nitrate with just a single instrument. A global calibration is provided that is valid for typical municipal wastewater compositions. Usually high correlation coefficients can be achieved using this standard setting. By running a local calibration improvements concerning trueness, precision and long term stability of the results can be achieved. The calibration model is built by means of PLS, various validation procedures and outlier tests to reach both high correlation quality and robustness. This paper describes the UV/VIS spectrometer and the calibration procedure.

Advanced treatment plant and sewer network control is a promising application of modelling in the... more Advanced treatment plant and sewer network control is a promising application of modelling in the field of urban wastewater management. At the same time there are only vague ideas about the measurement techniques that would be necessary for model based real time prognosis and control. One of he major tasks on the way towards online modelling is the search for and the validation of measurement techniques. An UV/VIS spectrometer (“spectro::lyser”) was successfully used for measuring organic matter at the highly dynamic inflow of a wastewater treatment plant. This poster describes the UV/VIS spectrometer, the calibration procedure and the results obtained.

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

Alarm parameters are in many ways different from measurements of well defined chemical substances... more Alarm parameters are in many ways different from measurements of well defined chemical substances. Being confronted with an increasing number of potentially harmful compounds as well as financial and logistic constraints, new variables (such as alarm parameters) that allow for an integrated assessment or for a first screening can be a solution. To monitor for surrogate or aggregate variables can be a useful strategy to overcome some of the constraints. It must be conceived that this can go along with losses in terms of comparability of results and even in tailor-made variables. Spectral data and their evolution over time are rich in information and compensate for losses due to aggregation and generalisation. Therefore it can be expected that alarm parameters developed from spectral data are transferable, accurate and selective to an extent which is beyond the state-of-the-art. The paper introduces time-resolved delta spectrometry, a method that was developed to generate alarm parame...

Using measurements of the whole UV/VIS spectrum enables to monitor changes in wastewater concentr... more Using measurements of the whole UV/VIS spectrum enables to monitor changes in wastewater concentration as well as in wastewater composition. Operators of wastewater treatment plants benefit when changes of concentration and/or composition of industrial inlets can be detected and therefore a possible failure of the treatment plant performance can be avoided. The instrument used is a submersible UV/VIS spectrometer (spectro::lyser by s::can Messtechnik, Vienna) that utilises the whole UV/VIS range between 200 and 750 nm. With just one single instrument nitrate, organic matter and suspended solids can be measured simultaneously. The spectrometer is installed directly in the process and measures in real-time. It is equipped with a very effective auto-cleaning system using pressured air that enables measurements at the influent of a wastewater treatment plant or directly in the sewer for several weeks (> 4) without maintenance. The paper shows influent measurements at a wastewater tre...

s-can.asia

... THE SUBMERSIBLE SPECTROMETER UV/VIS spectroscopy is a well known and accepted method for BTX ... more ... THE SUBMERSIBLE SPECTROMETER UV/VIS spectroscopy is a well known and accepted method for BTX measurement on higher concentration levels (Rinke and Hartig ... It is a 2-beam 256 pixel UV/VIS spectrometer, with a Xenon lamp as a light source and a path length of 80 ...

Water science and technology : a journal of the International Association on Water Pollution Research, 2003

There is no doubt that respirometry is a useful measurement principle in the field of wastewater ... more There is no doubt that respirometry is a useful measurement principle in the field of wastewater treatment. Although a large variety of methods and case studies have been published, respirometry has become neither a standard tool for control nor for assessment and optimisation of treatment plants. drawback of the conventional method for determining nitrification kinetics is the long experimental time. This disadvantage can be avoided by "turning over" the experiment. Starting with low ammonia concentrations the steep slope of the Monod curve is measured first. The low concentration branch of the Monod curve is also the part where e.g. inhibition can be detected. Therefore the proposed procedure allows us to speed up the measurement of nitrification kinetics and to measure nitrification inhibition on-line.

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

A submersible UV/VIS spectrometer was used to monitor a pilot-scale sequencing batch reactor (SBR... more A submersible UV/VIS spectrometer was used to monitor a pilot-scale sequencing batch reactor (SBR). The instrument utilises the whole UV/VIS range between 200 and 750 nm. With just one single instrument nitrate, organic matter and suspended solids can be measured simultaneously. The spectrometer is installed directly in the reactor, measures in real-time, and is equipped with an auto-cleaning system using pressured air. The paper shows the calibration results for measurements in the SBR tank, time series for typical SBR cycles, and proposes possible ways for optimisation of the operation by using these measurements.

Continuous monitoring of the COD and its fractionation in wastewater is by far no trivial issue, ... more Continuous monitoring of the COD and its fractionation in wastewater is by far no trivial issue, because of the many influences on the measurement quality. Especially in raw wastewater or primary clarifier effluent effects like failure of the probe-sampling or -preparation system, unrepresentative sampling or sensor fouling can lead to substantial errors in the measurement results. A new submersible spectrometer is presented, which utilises the UV-VIS-range (200-750 nm) for simultaneous measurement of COD, COD fractionation, turbidity and nitrate with just one single instrument. The miniaturised spectrometer allows easy installation even in 2" boreholes for groundwater monitoring. It is a sensor installed directly in the process, thus requires no sampling, sample preparation, no reagents and is equipped with an auto-cleaning system. The spectrometer was tested at three different WWTP´s in Austria, Germany and Switzerland. It proved to work extremely reliably even in raw wastewater upstream the screening station and over long periods. The instrument can be calibrated to the measurement location specific wastewater matrices and therefore opens new possibilities with respect to data quality. A validation only of the sensor itself showed that the instrument delivers results with a very good repeatability (mean stddev. = 2.08 mg COD /l, CV = 0.83% of mean value). From field test results the trueness was calculated to zero as the mean of the residuals with a 95%-confidence interval of 13.7 mg COD /l. The precision was ±50-60 mg COD /l (95%-confidence interval for a predicted value). It was concluded that the main influence on the precision are changes of the wastewater matrix changes that are not included in the instrument calibration. The test results clearly indicate that continuous monitoring of COD and its fractionation delivers improved quality of dynamic data compared to discontinuous laboratory analysis. Such data is valuable for dynamic simulation of wastewater treatment plants -especially in case processes are simulated -like excess biological phosphorous uptake -which are strongly influenced by dynamic changes of the concentration of the COD fractions.

Chemie Ingenieur Technik, 2002

Water Science & Technology

A prototype sensing system for in-situ monitoring of volatile organic compounds in contaminated g... more A prototype sensing system for in-situ monitoring of volatile organic compounds in contaminated groundwater was tested at a pilot scale plant. The sensor consists of a commercially available Fourier transform infrared spectrometer, connected to a 6 m long infrared transparent silver halide fibre optic cable. A 10 cm long core-only section at the centre of the fibre is mounted on a sensor head and coated with a hydrophobic polymer layer, while the remaining fibre is protected by Teflon tubing and thus not in contact with the surrounding media. The sensor head was immersed into the monitoring wells of the pilot plant testing the sensor system under circumstances close to field conditions and typical for in-situ measurements. The pilot plant consists of a 1 m3 cubic tank filled with gravel. A pump is used to circulate water horizontally through the tank, simulating a natural aquifer. The evolution of the concentration of analytes injected into the system is monitored with time using th...

Water science and technology : a journal of the International Association on Water Pollution Research, 2004

An in-situ UV spectrometer was applied to the effluent of a WWTP in Switzerland and calibrated us... more 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 du...

Water science and technology : a journal of the International Association on Water Pollution Research, 2002

For the protection of bankside wells and a groundwater recharge an early warning system had to be... more For the protection of bankside wells and a groundwater recharge an early warning system had to be developed. The monitoring network design is based on sensor measurements only. For this purpose a new submersible spectrometer has been successfully tested for multi-parameter measurements directly in the medium. The developed system can easily be upgraded with other new sensors. Only calibration and validation data are supplied by conventional grab sampling and laboratory analysis.. A conventional testfilter improved by on-line monitoring at 5 sampling sites serves as a reference system. The whole system is equipped with remote control and the internet serves as the control centre of the network. All measurement data from all 9 sites are available in real time on the internet.

Water Science & Technology, 2008

The EU-WFD requires certain monitoring tasks, which yet cannot be fulfilled by automated monitori... more The EU-WFD requires certain monitoring tasks, which yet cannot be fulfilled by automated monitoring devices. Nevertheless, the technical progress of recent years allows monitoring station designs, which enable long-term field application under reasonable maintenance demand. State-of-the-art monitoring stations allow the setup and operation of intelligent monitoring networks, which deliver quality proved and utilisable information to the end-user as opposed to a collection of time-series. Based on a full-scale example monitoring station design, long-term observations and possible ways of (automated) data interpretation are discussed.